Axon degeneration and Neuromuscular Junction (NMJ) disruption are key pathologies in the fatal neurodegenerative disease Amyotrophic Lateral Sclerosis (ALS). Despite accumulating evidence that axons and NMJs are impacted at a very early stage of the disease, current knowledge about the mechanisms leading to their degeneration remains elusive. Cytoplasmic mislocalization and accumulation of the protein TDP-43 are considered key pathological hallmarks of ALS, as they occur in ~ 97% of ALS patients, both sporadic and familial. Recent studies have identified pathological accumulation of TDP-43 in intramuscular nerves of muscle biopsies collected from pre-diagnosed, early symptomatic ALS patients. These findings suggest a gain of function for TDP-43 in axons, which might facilitate early NMJ disruption. In this review, we dissect the process leading to axonal TDP-43 accumulation and phosphorylation, discuss the known and hypothesized roles TDP-43 plays in healthy axons, and review possible mechanisms that connect TDP-43 pathology to the axon and NMJ degeneration in ALS. For many years, the molecular basis of neuromuscular junction (NMJ) disruption and motor neuron death in the fatal neurodegenerative disease Amyotrophic Lateral Sclerosis (ALS) has remained elusive. Recent fundamental discoveries in axonal biology in health and disease have advanced our understanding of the local and independent subcellular mechanisms that sustain motor neuron axonal function and integrity. Several of those discoveries also highlighted the pivotal contribution of axonal degeneration to the development and progression of ALS pathology. These may mark a new era for the development of novel therapeutic strategies, as well as diagnostic tools for this lethal disease.TARDBP, were reported in about 0.5% of ALS patients  [TAR DNA Binding Protein TDP-43) is a DNA and RNA binding protein that belongs to a group of heterogenous nuclear ribonuclear proteins (hnRNPs). TDP-43 was first discovered in 1995 by Ou and colleagues as a protein that binds the pyrimidine-rich motifs within the TAR DNA of human immunodeficiency virus-1 (HIV-1) . Ever si is a DNAc forms) , 15.A primary interest in the non-nuclear roles of TDP-43 began shortly after discovering the presence of phosphorylated and ubiquitinated cytoplasmic inclusions of TDP-43 within motor neurons in the brains of patients with ALS and Frontotemporal Dementia (FTD) , 17. SomMotor neuron axons are the longest and most arborized ones in the nervous system. The volume of motor neuron axonal and synaptic cytoplasm  exceeds that of the cell body by several orders of magnitude, and thus also its protein content. It has now been established that local protein synthesis and axonal transport are two essential mechanisms by which motor neurons use to regulate their axonal and synaptic proteome . AlteratALS is a neurodegenerative disease that targets lower and upper motor neurons, with vast heterogeneity of proposed mechanisms that lead to toxicity in the disease. However, the existence of one common pathology has wide approval among experts, the presence of cytoplasmic inclusions of TDP-43 protein. Still, the notion that TDP-43 cytoplasmic inclusions can also accumulate in remote processes and facilitate local pathology in axons and synapses was until recently, a topic of controversy. This issue directly relates to the “dying back” theory, which depicts the NMJ and axons as the primary location for degeneration in the disease , 29. FolA key fact, which is often being neglected when discussing TDP-43 pathology in ALS, is that most of the existing data regarding human ALS patient tissues are of hyperphosphorylated TDP-43 cytoplasmic inclusions. Early reports for the presence of TDP-43 phosphorylation (pTDP-43) came together with the finding that TDP-43 is a common pathology of ALS . FurtherSeveral cellular mechanisms may explain the increase in local concentrations of proteins within axons: 1. Enhancement in cytoplasmic localization and axonal transport towards the nerve ending. 2. Decrease in axonal degradation and clearance. 3. Cell-to-cell protein transmission. 4. Local protein synthesis in axons. Although there is no concrete evidence as to which possibility is most likely in the case of TDP-43, several recent discoveries revealed few relevant pathways for this phenomenon in ALS  . TDP-43 Like other phosphorylated proteins, there is an enzymatic pathway coordinating TDP-43 phosphorylation, which is mediated by kinases and phosphatases. Five known kinases can directly phosphorylate TDP-43: Casein kinases 1 and 2 , Tau tubulin kinases 1 and 2  and Cell division cycle 7 (CDC7) kinase . Among tC.elegans models of TDP-43 proteinopathy, genetic deletion of calcineurin homolog gene tax-6 can lead to excess accumulation of pTDP-43 and motor dysfunction, while treatment with the calcineurin inhibitor tacrolimus rescued the motor phenotype [With regard to the opposite regulation of TDP-43 phosphorylation, the phosphatases Calcineurin, PP1 and PP2 have been shown to have a direct impact on TDP-43 phosphorylation . It was henotype . As for henotype .Still, regarding the activity of those kinases and phosphatases in the regulation of TDP-43 phosphorylation in axons and its functional outcomes, data is sparse at best. One possibility is that axonal kinase activity might be influenced indirectly from TDP-43 phosphorylation by itself. For example, CK2, a kinase known to phosphorylate TDP-43, was found to enhance axon growth by phosphorylating G3BP1 . G3BP1 pTwo pivotal questions which remain open are how TDP-43 is capable of mediating excessive damage to motor neuron axons and NMJs, and if there is higher vulnerability of those distal segments to TDP-43 condensation compared to cell bodies. To address those issues, it is first necessary to understand the unique properties of motor neurons and the roles TDP-43 has in supporting their growth and maintenance. Motor neuron axons are of the longest and most arborized axons in the human body. To coordinate complex spatiotemporal processes within their highly compartmentalized cytoplasm, neurons have adapted key mechanisms such as axonal transport of essential proteins , 82, orgOwing to the tremendous efforts invested in identifying TDP-43 interactors and TDP-43-bound mRNA, our knowledge of the cytoplasmic role of TDP-43 and more specifically in axons advanced in recent years. As TDP-43 is strongly associated with the formation of cytoplasmic and axonal inclusions in ALS, data from studies on these pathological forms assisted to reveal the normal context of TDP-43 at those subcellular environments. Various approaches were used to characterize the TDP-43-bound, and TDP-43-associated RNA populations in the nucleus, as well as in the cytoplasm , 97. SepNefl, Map1b) and mitostasis process  [Due to the spatial complexity of motor neurons, and considering the axonal pathology in ALS, a key unresolved question is identifying the RNAs associated with TDP-43 also in axons and NMJs. Alami and colleagues have identified that TDP-43 is a component of axonal mRNA granules where it binds and shuttles RNA . TDP-43  ATP5A1) . Moreove ATP5A1) . Recentl ATP5A1) , while o ATP5A1) , 100. Ci ATP5A1) . TDP-43  ATP5A1)  and was  ATP5A1) , 102. He ATP5A1) , 102–104Many publications in the recent decade have established that axons and synapses rely on local protein synthesis in order to develop, function, respond to changes, and maintain themselves , 106. YeA315T in motor neuron-like cortical neurons does not affect global protein synthesis, however, it does enhance the translation of specific transcripts, including Camta1 and Mig12, and that overexpression of mutant TDP-43A315T also enhances translation of Dennda4 mRNA [Drosophila Melanogaster models, Coyne et al., have shown that TDP-43 and drosophila FMRP colocalize together in PABP-positive stress granules in cultured neurons from TDP-43 overexpression model flies. The authors further show that overexpression of TDP-43 inhibits the translation of drosophila NMJ-associated futsch mRNA by its sequestration in these stress granules [Accumulating evidence indicates that these processes are controlled by the dynamic assembly and dissolution of RNP granules , 108. Thda4 mRNA . In Drosgranules . Hence, granules . Similargranules , hintingAxonal and synaptic mitochondria have been shown to depend on local protein synthesis of nuclear-encoded mitochondrial mRNAs in order to properly function , 117–119Following mitochondrial ones, transcripts encoding ribosomal subunits were also reported to occupy large proportions of axonal transcriptome , 122. ReAnother layer of regulation over translation is achieved by microRNAs (miRNA). miRNAs are short, 20–22 nucleotide non-coding RNA that mediate posttranscriptional silencing of their tens to hundreds of target mRNAs, some of which encode protein families that promote a specific function or pathway . As suchCollectively, this evidence marks cytoplasmic and axonal TDP-43 as a regulator of the axonal transcriptome and proteome. Yet, the mechanisms that regulate TDP-43 and control its ability to perform distinct properties over space and time in motor neuron axons and synapses remain to be determined. The post-transcriptional modifications which TDP-43 has been described to undergo, like phosphorylation, are one possible explanation for how TDP-43 switches between its different functions and localizations (nucleus/cytoplasm/axons), but may also cause neurodegeneration when are aberrantly made in space, time and intensity. It is highly important to understand how those switches occur, and even more so how we can interfere with them early enough to slow or prevent motor neuron degeneration in ALS.As years go by, scientific discoveries have promoted our understanding of ALS disease etiology, genetics, pathology and progression. Still, those achievements did not yet translate into the clinic. Therefore, it is necessary to ask, are we “looking under the lamp”?. Meaning, are current therapeutic interventions developed for ALS the most likely to succeed or the most available for testing. One key point regards the relative overlook of axonal projections and NMJs when trying to analyze ALS pathology. Until recently, the knowledge about ALS pathology was based mostly on histological sections of post-mortem CNS tissues, such as the brain and spinal cord , 30, 33.An important topic, which was discussed earlier, is the ability of TDP-43 protein to form cytoplasmic condensates. Still, little is known regarding the presence of those condensates in axons and their ability to form and dissolve in axons of ALS models. Over the last 10 years, a liquid-to-solid phase transition has become a central mechanism in ALS pathology –144. MulAdditionally, the function of RNP condensates in axons and synapses is also understudied. Gopal et al. revealed that axonal TDP-43 has influence on the solubility of RNP granules, and mutations in TDP-43 can influence its axonal transport . A recenTargeting motor neuron axons and NMJs with novel therapies early in the disease course might prove to be beneficial for some additional reasons. One possible advantage can be the increased pharmacological accessibility of peripheral nerves. Traditionally, it is difficult to develop and administer therapies for neurological diseases, due to the complex process of efficiently crossing the blood–brain barrier in order to reach adequate drug concentrations in the cerebrospinal fluid. If indeed the formation of pTDP-43 disease-causing condensates is initiated in peripheral axons and NMJs, it is possible that blocking this process can delay the disease or even prevent it from affecting the spinal cord where motor neuron cell bodies are located. There are already known compounds that were shown to inhibit TDP-43 phosphorylation and even to block condensate formation which might be used . HoweverThe novel finding regarding the presence of pTDP-43 pathology in peripheral motor neuron axons of ALS patients provides an exciting new perspective for understanding ALS pathology and etiology, as well as an avenue for developing new therapeutic approaches. Together with recent discoveries regarding the importance of TDP-43 in axonal health and the implications of its phosphorylation on RNA biology, local protein synthesis, and mitochondrial viability, an urgent need for timely research is at hand. One possible hypothesis which will need further proof is that the initial step in the disease is enhanced axonal localization of TDP-43 at distal motor nerves. This process can lead to a buildup of pTDP-43 condensates in the NMJ, which in turn facilitates repression in local protein synthesis, mainly of mitochondrial and ribosomal proteins. The following result is the failure of the NMJ to maintain enough functioning mitochondria and ATP, resulting in the accumulation of reactive oxygen species and NMJ degeneration, delivering a retrograde signal causing motor neuron cell death (Fig.


Sarcoidosis is a multisystemic disease of unknown etiology characterized by the formation of granulomas in various organs, especially lung and mediastinal hilar lymph nodes. The clinical course and manifestations are unpredictable: spontaneous remission can occur in approximately two thirds of patients; up to 20% of patients have chronic course of the lung disease  resulting in progressive loss of lung function, sometimes life-threatening that can lead to respiratory failure and death. The immunopathology mechanism leading from granuloma formation to the fibrosis in APS still remains elusive. Recent studies have provided new insights into the genetic factors and immune components involved in the clinical manifestation of the disease. In this review we aim to summarize the clinical-prognostic characteristics and molecular pathways which are believed to be associated with the development of APS. Sarcoidosis is a systemic disorder characterized by granulomatous reactions related to an unknown cause and occurring in any organ, likewise lung, eye, liver, nervous system, skin, spleen and also heart, even though the pulmonary involvement is recognized in nearby the totality of affected patients .As many other interstitial lung diseases (ILDs) ,3,4,5 thhttps://doi.org/10.1253/jcj.64.679, accessed on 20 June 2023) . During the pandemic, patients with APS were considered at higher risk of mortality because of the multi systemic inflammatory environment caused both by SARS-CoV-2 infection and sarcoidosis .The term advanced pulmonary sarcoidosis (APS) refers to pulmonary fibrosis, complicated with bronchiectasis and/or infections, and pulmonary hypertension. Although cardiac and neurological involvement are common causes for sarcoidosis-related death, APS is the leading cause of poor outcomes and responsible for increased hospitalization and mortality rates among affected patients both in Europe and in US ,7,8 (httNumerous genome-wide association studies (GWAS) performed in sporadic and familial cases of sarcoidosis  suggested a synergistic role of different immune pathways . PolymorMoreover, many key cells like T cells and macrophages are involved in granuloma formation. Persistent inflammation is suggested to be a risk factor or a precursor of irreversible fibrosis. However, many authors assert that chronic sarcoidosis is not simply the natural consequence of the acute phase for sarcoidosis, because not each patient with chronic inflammation will develop fibrosis. To date, the effective link between granuloma formation and fibrosis in APS remains still unsolved. Corticosteroids are the most common first-line drugs used, while the antimetabolites and biological agents representing an alternative second and third-line choice for patients who failed with corticosteroids or who cannot tolerate them ,10.Recently antifibrotic medication (nintedanib) has been approved in progressive fibrotic lung diseases including sarcoidosis, once other immunosuppressive therapies have been exhausted . NonetheThis review focuses on APS addressing its clinical-prognostic characteristics and molecular pathways that are believed to explain this progressive fibrosing lung disorder.Pulmonary involvement is recognized in nearby the totality of patients affected by sarcoidosis, even though most patients are asymptomatic or present symptoms suggestive for a systemic involvement. APS with fibrosis occurs in 10–20% of sarcoid patients, and it is the main cause of respiratory failure and death .There are no typical symptoms of fibrotic pulmonary sarcoidosis as dry cough, dyspnoea on effort and chest discomfort are common presenting symptoms for patients with pulmonary sarcoidosis without significant fibrosis . In addiPulmonary function tests of advanced sarcoid patients present both restrictive and obstructive patterns, sometimes even with a mixed pattern ,11. HowePulmonary hypertension (PH) is a typical complication in 5–28% of patients with pulmonary sarcoidosis and occurs especially in up to 74% of patients with advanced sarcoidosis . This coSome clinical parameters have been suggested as prognostic predictors for mortality in patients with APS, in particular the occurrence of respiratory failure has been considered the most common cause of sarcoidosis-related death . IdentifIn 2011, Nardi A. and colleagues described the causes of death in 142 advanced pulmonary sarcoid patients compared to a matched general population along a ten years follow up. During the observational period, PH developed in 30% of APS patients and sixteen of 142 patients died. Main causes of deaths were refractory PH and respiratory failure  are detectable in the bronchoalveolar lavage (BAL) fluid .The polarization of T cells in Th1 type via MHC class II molecules is essential for granuloma formations ,59. Th1 Phagocytosis is the main role of alveolar macrophages. In the alveolar spaces, macrophages remove microorganisms, debris and old unfunctional cells . MacrophTGF-β/Smad signaling represents an important key pathway during inflammatory mitigation and wound healing . MoreoveThe release of IFN-γ is regulated by the Janus kinase/signaling transducer and activator of transcription (JAK/STAT) pathway . To datehttps://doi.org/10.1016/j.semarthrit.2022.152102, accessed on 20 June 2023). Other studies are needed to identify the role of this pathway in the development of pulmonary fibrosis.The protein kinase mTOR (mechanistic target of rapamycin) is involved in many regulatory and proliferation mechanisms, forming two different complexes called mTOR complex 1 and mTOR complex 2 (mTORC1 and mTORC2)  mTOR is The signaling wingless/integrated (Wnt) was discovered for the first time in the carcinogenesis process  and its In advanced pulmonary sarcoidosis, the histological abnormalities maintain the typical distribution along lymphatic routes of pleura, interlobular septa, and bronchovascular bundles, but the typical sarcoid non caseating granuloma loses its chronic lymphocytic infiltrate proceeding towards the fibrotic pathway . Indeed,ILDs and APS are different clinical diseases sharing a progressive deterioration in lung function, physical performance, and quality of life. The diagnosis of sarcoidosis requires compatible clinical and radiological features together with the evidence of non-necrotizing granulomatous inflammation at disease sites. The diagnosis of IPF, the most frequent among the ILD of unknown origin, is reachable after the exclusion of known factors for interstitial lung diseases, and with the presence of radiological and/or radiological pattern of UIP. In the radiological section, we described that a radiological UIP pattern on HRCT similar to IPF may be detected in APS. Based on radiological criteria, UIP pattern in IPF is typically characterized by peripheral and basal predominant reticulations associated to subpleural traction bronchiectasis and honeycombing, whereas in APS fibrotic abnormalities, as well as honeycombing, typically present a peri-bronchovascular and upper lobe predominant distribution. Some patients may present concomitant clinical and radiological features of IPF and sarcoidosis. Combined Sarcoidosis and IPF (CSIPF) may represent a distinct phenotype of these two entities, with different genetic predisposition a different course, or may simply be the coexisting of these two entities in the same patient . RecentlFibrotic sarcoidosis remains a dangerous and severe disease. The main goals of new therapies are the restoration of the normal M1/Th1–M2/Th2 axis and the prevention of chronic lung infections. As reported in the most recent guidelines, oral glucocorticoids represent the first line treatment in patients with every form of sarcoidosis but evidence that they can prevent progression of pulmonary fibrosis is still scarce . MoreoveClinicalTrials.gov Identifier: NCT03260556, accessed on 20 June 2023). Lung transplantation could be a surgical option for patients with end-stage fibrotic pulmonary sarcoidosis. Interestingly, among patients with sarcoidosis listed for lung transplant have been reported unexpected sudden death and other causes of mortality [In fibrotic sarcoidosis, physicians have to actively look for halting the functional decline and disease progression. Antifibrotic therapy (nintedanib and pirfenidone) has been widely used in IPF and could represent a novel strategy to reduce disease progression also in fibrotic pulmonary sarcoidosis. Recently, the role of nintedanib and pirfenidone has been evaluated in progressive ILD, including fibrotic sarcoidosis ,101. In ortality ,103. Lung transplantation is usually a last resort for patients who have a very severe lung damage and reached respiratory impairment due to pharmacological treatment failure. Currently, guideline consideration of lung transplant for APS follows those for ILD in general, as there are no specific guidelines for sarcoidosis and includes functional progression, supplemental oxygen requirement, poor lung function and a failure to improve after a trial of medical therapy . This suThe pathogenetic mechanism that leads to pulmonary fibrosis in sarcoidosis is still mysterious and unsolved. Studying different phenotypes and genotypes should be pivotal for increasing our knowledge and for the development of new clinical approaches and therapies. Moreover, further studies should be focused identifying those patients at increased risk of pulmonary fibrosis and disease progression.


Uncontrolled human and industrial activities lead to the increase in demand for selective gas sensors for detection of poisonous gases in our environment. Conventional resistive gas sensors suffer from predetermined sensitivity and poor selectivity among gases. This paper demonstrates curcumin reduced graphene oxide-silk field effect transistor for selective and sensitive detection of ammonia in air. The sensing layer was characterized by X-ray diffraction, FESEM and HRTEM to confirm its structural and morphological features. Raman spectroscopy, Fourier transform infrared spectroscopy and X-ray photoelectron spectroscopy was carried out to analyze the functional moieties present in the sensing layer. Curcumin reduced graphene oxide introduces sufficient hydroxyl groups in the sensing layer to provide high degree of selectivity towards ammonia vapors. The performance of the sensor device was evaluated at positive, negative and zero gate voltage. Carrier modulation in the channel through gate electrostatics revealed that the minority carriers (electrons) in p-type reduced graphene oxide plays a pivotal role in enhancement of sensitivity of the sensor device. The sensor response was enhanced to 634% for 50 ppm ammonia at 0.6 V gate voltage compared to 23.2% and 39.3% at 0 V and − 3 V respectively. The sensor exhibited faster response and recovery at 0.6 V owing to higher mobility of electrons and quick charge transfer mechanism. The sensor exhibited satisfactory humidity resistant characteristics and high stability. Hence, curcumin reduced graphene oxide-silk field effect transistor device with proper gate bias elucidates excellent ammonia detection and may be a potential candidate for future room temperature, low power, portable gas detection system. These demands call for intensive research towards fabrication of miniaturized, room temperature and low power gas sensors. In this context, sensing layers based on metal oxide semiconductors  are widely explored. These sensing layers are highly attractive due to their enormous sensitivity, but their functioning requires high operating temperatures . The high-power budget of metal oxides limits their usage in hand held, room temperature gas detection systems. For example, SnO2 based Taguchi sensors  that are available commercially, utilizes 200 mW power. Hence, efforts are required to develop room temperature, low power sensors. There are several attempts in this regard9, which aim to integrate the sensors with the matured CMOS platform. Certain gases like ammonia, hydrogen sulfide have low ignition temperature and are highly flammable. Therefore, researchers have focused towards synthesis of functionalized nanomaterials that operate at room temperatures. These materials include two-dimensional nanomaterials (graphene), transition metal di-chalcogenides , black phosphorus, metal organic frameworks, etc.Due to the rise of activities in chemical, food and automobile industries, there is a significant demand for development of hand held and battery operated10. Graphene is found to be highly sensitive towards different gas analytes. The two-dimensional honeycomb structure along with single layer of carbon atoms facilitate higher sensitivity towards different analytes. Pristine graphene which is free of defects, has poor adsorption energy towards different gases. Introducing defects and dopants in the graphene matrix shall enhance the adsorption energy level and facilitate better charge transfer between the target analytes and graphene matrix. Chemical exfoliation of graphene leads to graphene oxide, which on reduction produces reduced graphene oxide (RGO). Reduced graphene oxide consists of several defect sites along with various functional moieties, that introduces several active sites for adsorption of target gases. The biggest advantage of RGO is its ability to detect trace gases even at room temperature. This makes RGO an ideal candidate to be utilized in future generation room temperature, low power, portable gas sensors.Graphene, a two-dimensional nanomaterial has found significant attention due to its enormous surface area, thermal and mechanical stability, high mobility, and flexibility12. In case of prolonged exposure, severe health issues are observed in human beings, including death. According to OSHA , 15–28% ammonia concentration by volume in air is considered highly dangerous to health13. The flammable nature of ammonia demands fabrication of sensors that must operate at room temperature. Few chemo-resistive ammonia sensors based on graphene are developed21, however their performances are not satisfactory. RGO based sensors that are previously reported, suffer from large response and recovery, baseline drift, poor recoverability, and unsatisfactory selectivity. Earlier reports on graphene-based gas sensors lack analysis under humidity environments. In case of resistive sensors, once the sensing layer gets deposited, it cannot be further tuned or modulated. These factors boost the motivation towards development of Field effect transistor (FET) based gas sensors, where the channel can be modulated even after the sensor is fabricated. This strategy might facilitate “sensitivity enhancement” by controlling the number of effective carriers in the channel region22.In various industrial applications, ammonia is used as a common reagent. Ammonia is a highly pungent and toxic gas, which may cause severe effects on respiratory tracts, eyes, and skin, if exposed at higher concentrations (> 350 ppm)In the present work, a field effect transistor (FET) has been fabricated to detect ammonia vapors selectively. Curcumin reduced graphene oxide (Cur-rGO) is synthesized as the channel material and drop casted between the source and drain electrodes. Silk is used as the gate dielectric due to (i) high dielectric constant and (ii) ease of deposition. This reduces the fabrication cost and complexities. The current work demonstrates the play of gate voltage in tuning the type of charge carriers participating in the charge transfer/sensing mechanism. Even though RGO is known to be a p-type material, it is observed that application of proper gate voltage ensures electron participation for ammonia detection. During application of positive gate bias (0.6 V), the sensor exhibits enormous sensitivity of 634% at 50 ppm ammonia. When compared to zero gate bias (purely resistive-type) and negative gate bias, ~ 15 times enhancement in response is observed. The participation of electron enhances the rate of charge transfer, which is further reflected in response and recovery time analysis. The performance of these sensors under appropriate gate voltage reveals the significance of “optimization of gate electrostatics” in chemical sensors. The use of curcumin to reduce graphene oxide is also validated through Fourier transform infrared spectroscopy. The reduction through curcumin leads to complete removal of all other functional groups except hydroxyl (O–H bonds). These hydroxyl groups play a key role in determining the selectivity of the sensors towards ammonia. Cur-rGO was further characterized by FESEM, HRTEM, Raman spectroscopy and X-ray photoelectron spectroscopy to reveal its structural, morphological, and chemical properties. The Cur-rGO based silk FET exhibited good immunity against humidity and displayed good stability. Compared to the previous reports, its is evident that Cur-rGO silk FET with appropriate gate bias is highly efficient towards selective and sensitive detection of ammonia. These results prove that Cur-rGO silk FET based ammonia sensor can be used in future commercial low power, room temperature and portable gas detector systems.Morphological, structural, and compositional analysis of Cur-rGO was carried out through FESEM, HRTEM, XRD, FTIR, XPS and Raman spectroscopy. Figure 1 radiation (λ = 1.54 Å) equipped with a parallel beam diffractometer. Figure −1. The C=O bond at 1740 cm−1 relates to the carboxylic groups present at the edge of graphene sheet. The presence of C–O stretch at 1048 cm−1, C–O–C stretch at 1220 cm−1, C–OH stretch at 1373 cm−1 reflects the different functional moieties present in GO23. Thermal treatment of GO by curcumin leads to successful reduction of GO as confirmed by FTIR spectra. Apart from O–H stretching (centered at 3400 cm−1), all other functional groups are successfully removed from GO surface. The presence of this O–H group is highly influential towards selective detection of ammonia, compared to other VOCs.Examination of crystallographic orientation of the synthesized materials was carried out through XRD analysis having Cu Kα−1 and 1607 cm−1, however after reduction the D and G bands shifted to 1357 cm−1 and 1599 cm−1, which is in accordance with the previous reports25. The attachment of curcumin functionalities with the unsaturated carbon atoms leads to shifting of ‘D’ and ‘G’ bands to lower wave numbers. The electron donating curcumin leads to softening of phonons and shifts the fermi level27.Successful reduction through curcumin is further validated by Raman spectroscopy as shown in Fig. 3 molecules towards –OH groups.The curcumin reduced GO was further investigated by X-ray photoelectron spectroscopy (XPS) to further analyze the chemical states and functional groups. The deconvoluted XPS spectrum of C 1s region of Cur-rGO is shown in Fig. Reduction of GO in presence of curcumin leads to the formation of a highly sensitive ammonia sensing layer. The presence of field effect in the sensor devices allows modulation of charge carriers in the channel region. As reduced graphene oxide exhibits p-type characteristics, electrons play the role of minority carriers in all transport mechanisms. These electrons play a pivotal role towards highly sensitive detection of ammonia at low concentrations. It is predicted that charge transfer during sensing would be more efficient for electrons as compared to holes. Holes with a lesser mobility and higher effective mass would face larger hindrance towards fast charge transfer. Hence, it is focused to use electron as the main carrier for charge transfer by application of appropriate gate bias.28. The epoxy and hydroxyl groups in defect induced graphene sheets are found to have binding energies of be 0.219 eV and 0.840 eV respectively for ammonia28. This shows the importance of hydroxyl groups to be present over the sensor surface. When the applied gate voltage is negative or zero, holes are the carriers that take part in the sensing phenomenon. Ammonia molecules get bound to the hydroxyl groups and donates electrons to the Cur-rGO sensing layer as shown in Fig. Pristine graphene exhibits 0.114 eV adsorption energy towards ammoniad, gas and Id, air are the drain current upon exposure to ammonia and air respectively.Response is mathematically defined as:d-Vg characteristics (Vds = 1.5 V) in Fig. 5). With gate voltage less than 0.5 V, the device exhibits conductivity due to holes. However, after 0.5 V, the device exhibits electron conductivity. When the sensor is exposed to ammonia molecules, the hole current reduces (left of 0.5 V) but the electron current increases (right of 0.5 V). When the majority carriers are holes, then presence of ammonia molecules reduces the number of holes due to electron–hole recombination. Hence, a reduction in current is observed. With increased gate voltage above 0.5 V, the presence of ammonia donates electron in the channel. Now, electron being the majority carrier, its concentration increases and hence increase in current is observed.The I3 from 10 to 50 ppm. The concentration curve is shown at Vgs = 0.6 V, the best sensing condition. Figure gs and 39.3% with − 3 V Vgs. However, at Vgs = 0.6 V, there is tremendous increase in response to 634% for 50 ppm ammonia. This result signifies the essence of gate voltage optimization to increase the sensitivity of the sensing layer.Figure 3 molecules when compared to seven other VOCs . The current is observed to decrease with decrease in concentration, due to the n-type behavior of the channel at the desired gate voltage. Figure 3 at an optimized Vgs of 0.6 V. The sensor reaches the baseline current after the gas source is removed. The absence of baseline drift is a blessing in terms of calibration of the device.Figure gs = 0.6 V and Vgs = 0 V is illustrated in Fig. Response time is the time taken by the sensor response to reach 90% from 10% of the maximum value. Recovery time is the time taken by the sensor to recover from 90 to 10% of the maximum value. The response and recovery time of Cur-rGO at positive gate voltage (0.6 V) is lower compared to negative (− 3 V) and zero gate bias as shown in Fig. 3 is compared with previous works from literature as depicted in Table 3 at room temperature. The optimization of gate voltage to change the polarity of the channel and the presence of silk as dielectric ensures sensitive as well as low power operation. The proper reduction of graphene oxide by curcumin leaves behind hydroxyl groups, which facilitates selective ammonia sensing behaviour of the Cur-rGO Silk FET. Therefore, Cur-rGO Silk FET can be used in future commercial room temperature, low power ammonia gas detection systems.Hence, the effect of gate voltage towards enhancement of ammonia sensing performance for Cur-rGO introduces a new technique towards increasing of sensitivity in gas sensing domain. The performance of Cur-rGO towards NHGraphite powder, sodium nitrate, potassium permanganate, sulphuric acid, ammonia solution, ethanol, sodium carbonate, calcium chloride, formic acid and curcumin were obtained from Merck India pvt Ltd. and were used throughout the experiment without further purification. Commercially available Bombyx Mori silk was purchased from M/S Bombyx Mori Silks and Textiles, Srinagar, India. Millipore purification system was used for preparing de-ionized water.Widely known Hummer’s method was implemented towards synthesis of graphene oxide (GO) sheets by chemical exfoliation of graphite powder. For synthesis of curcumin reduced graphene oxide (Cur-rGO), solution of curcumin in ethanol was prepared by adding 5 mg curcumin to 10 ml ethanol. The solution was stirred for an hour to obtain a homogenous yellow solution. A beaker containing 100 ml GO dispersion (1 mg/ml) was constantly stirred and curcumin solution was added in dropwise manner to obtain a homogenous mixture. After stirring for 2 h, 20 μL of ammonia solution (27%) was added to attain a pH of 10. After further stirring for an hour, the solution was transferred to a blue capped reagent bottle. The solution was then heated at 85 °C in a hot air oven for 4 h. The resulting solution was cooled to room temperature and subjected to 2500 rpm centrifugation to eliminate unwanted impurities. The as prepared solution was termed Cur-rGO.29. Initially, a glue-like substance (Sericin), which binds the silk fibroins was removed. The fibroins were then dissolved to form a homogeneous solution. Sericin was removed from silk fibroins by treating it with 0.5% sodium carbonate-water solution at 110 °C for 1.5 h. In the next step, it was rinsed thoroughly with DI water and dried overnight. After the drying stage, the degummed silk was dissolved in a solution comprising of formic acid and calcium chloride (19:1), leading to regenerated silk fibroin solution. The presence of inorganic salts with formic acid facilitates dissolution of degummed silk. Calcium chloride penetrates the structure while formic acid enables swelling of silk. Penetration of these salts disrupts the hydrogen bonding between the fibroin protein chains and decomposes it to micro-sized fibrils and finally to nanofibrils. The solution was then casted onto a petri dish and dried at 60 °C. After drying, the film was immersed overnight in DI water to remove calcium chloride, as it causes detrimental effects on thin film properties. The film can be dissolved and reconstituted in formic acid directly, as, and when required.Dielectric silk solution was prepared by a method proposed by Sarkar et al.Fabrication of silk gate field effect transistor (Silk-FET) was carried out on p <100> type silicon wafer having resistivity 4–20 Ω-cm. A 200 nm thermal oxide (dry–wet-dry) was grown over silicon to achieve proper insulation. Deposition of 50 nm aluminum layer was carried out by thermal evaporation, which acted as the gate electrode. Dielectric layer of 200 nm silk solution was spin coated over the aluminum film. Source and drain electrodes were fabricated using DC sputtering, 20 nm titanium (Ti) adhesive layer was deposited followed by 100 nm gold (Au) through a shadow mask. Interdigit gap of 200 μm was achieved between the fingers. The width of the electrodes was 500 μm. The sensing material (Cur-rGO) was deposited onto the gaps by simple drop casting technique. The schematic of the fabricated Silk-FET device is depicted in Fig.


We then give an overview of the optimization strategies for graphene-based photocatalysis and the latest advances in its application. Finally, we present challenges and perspectives for graphene-based applications in this field in light of recent developments.The global energy shortage and environmental degradation are two major issues of concern in today’s society. The production of renewable energy and the treatment of pollutants are currently the mainstream research directions in the field of photocatalysis. In addition, over the last decade or so, graphene (GR) has been widely used in photocatalysis due to its unique physical and chemical properties, such as its large light-absorption range, high adsorption capacity, large specific surface area, and excellent electronic conductivity. Here, we first introduce the unique properties of graphene, such as its high specific surface area, chemical stability, etc. Then, the basic principles of photocatalytic hydrolysis, pollutant degradation, and the photocatalytic reduction of CO The excessive development of fossil energy causes energy shortage and also promotes the excessive emission of CO2. Various environmental pollution problems around the world are becoming more and more serious . Th. Th93].  process ,95,96. TOverall water decomposition reaction:Complete water decomposition reaction:2, the CO2 that is generally reduced to CO can also be reduced to methane or ethane using special materials [During the catalytic splitting of water into Haterials .The photocatalytic reaction of metal oxides contains the above general photocatalytic reaction mechanism. The difference is that metal oxide photocatalysis mainly involves a catalyst containing transition metals. The whole cycle includes four main steps: oxidation, reduction, addition, and removal. The main mechanism is that the d-orbital electrons in the transition metal has the characteristics of easy separation or addition, which makes it easier to carry out redox reactions. At the same time, the requirement of d-orbital bonding and bond-angle matching is low and the bonding energy is not high, which is beneficial for the formation of low-orbital bonding of reactants. In some of the transition metal catalytic systems, after the introduction of platinum, palladium, rhodium, silver, and other precious metals, these transition metals can be used as photon acceptors to produce photoelectrons, which is conducive to the formation of active compounds, quantum light, and effective hole separation ,99.2-composite graphene nanomaterials have been proved to have better photoelectrochemical activity and photocatalytic activity [2. At the same time, a Ti–O–C bond is formed that introduces the TiO2 bandgap intermediate state to promote a visible light reaction. Unfortunately, TiO2 also has the limitation of a light wave frequency. It is only suitable for the ultraviolet band, while ultraviolet only accounts for 4% of the solar spectrum, and a large number of electromagnetic waves in the band cannot be used [2 photocatalytic derivatives of new materials have emerged ceaselessly and have been developed into a variety of composite types of metal oxides, organic photocatalytic semiconductors, etc. An organic photocatalytic semiconductor is a good alternative material. Its efficient photoelectric conversion efficiency and longer service life have a profound impact on solving the increasingly tense resource and environmental crisis and energy shortage. However, an unsatisfactory aspect is that there are fewer active sites in the material, the two carriers excited by the energy given by the light have a short interval, and the overall photocatalytic efficiency is not high, which make the development of this material still have great limitations [Graphene can be doped with B, Se, N, P, O, S, F, Cl, Br, I, etc. ,106,107.activity ,111,112. be used . In ordeitations ,115.In addition to metal-based materials, graphene-based composite conductive materials are also promising research directions. The main problem of this graphene-based material is that the free electrons and holes diffuse from the conduction band and valence band and then the free electrons and holes recombine quickly, losing the conductivity. This phenomenon affects photochemical stability and ultimately leads to a decrease in photocatalytic efficiency. The macroscopic performance shows that the material has high resistance. At present, there are a large number of strategies to solve the problem of the recombination of free electrons and holes excited by the optical quantum ,118,119.In addition to the above mentioned, graphene can be used as a photocatalytic material substrate and as a co-catalyst. In order to improve the photocatalytic effect of graphene materials, doped N has particularly prominent derivatives ,123. At Graphene’s ability to function as a photocatalytic substrate material and auxiliary material has a lot to do with its structure . It is wThe enhanced catalytic effect of high-dimensional graphene can be attributed to the fact that, compared with one-dimensional graphene, two-dimensional and three-dimensional graphene can reduce the Coulomb binding energy of electron holes and increase the specific surface area to solve the shortcomings of the loose substrate contact and fewer active sites on graphene. At the same time, fixing metals at specific sites can also avoid the aggregation of metal oxides . In part3N4) is a two-dimensional material that has been intensively studied in ozone oxidation and in composites with rhodium phosphide [3N4 material with heterostructural defects. They observed enhanced water-splitting hydrogen-production efficiency and photocatalytic H2-evolution activity by the heterojunction and the construction of defective ultrathin two-dimensional materials, respectively [3N4 and divided it into three groups: g-C2.52N4, g-C1.95N4 and g-C1.85N4. These three groups were also doped with Ag–Pd to form a two-dimensional composite material that strongly promoted photocatalysis. They controlled the ratio of carbon and nitrogen, and the removal rate of NO2− and NO3− was used as a reference for the degree of photocatalytic reaction. The XRD pattern showed that g-C1.95N4 had the best photocatalytic activity. After 3 h of reaction, the removal rate of NO3− was 87.4%, and the removal rate of NO2− was 61.8% [Graphitic Carbon Nitride  on TiO2-functionalized graphene (TiO2-FG) without adding precious metal co-catalysts. The porous HCP–TiO2 graphene composite structure was used as a photocatalytic material to achieve a CO2 absorption capacity of 12.87 wt% and a CH4 yield of 27.62 μmol g−1 h−1. The principle of effective CO2 absorption in this process is to introduce the material into the HCP layer  [2 into amorphous TiO2, Ti atoms are rearranged, GO is reduced, and unpaired electrons are formed. The unpaired electrons and Ti atoms reduce the conduction-band level of TiO2, thereby reducing the band gap and improving the conductivity and photocatalytic effect. Qiu’s team provided a new idea for the treatment of graphene heterostructures by self-doping Ti3+ to place GO and TiO2 on the surface of graphene. GO-cracking into small size graphene; the smaller the size of the graphene, the more binding surface with TiO2 there is in the structure to promote the efficiency of photocatalysis. Moreover, this process also generates Ti–O–C bonds to form shallow surface defects, and the band gap is slightly reduced and red-shifted to 2.98 eV [Lee et al. provided a heterostructural treatment of graphite carbon three-dimensional nanomaterials. The team used hydrothermal treatment and the simultaneous reduction of GO and TiO2.80 eV) . Through 2.98 eV .3N4/GO (p-CNG)) is also a good idea. Li’s team fixed Au, Pd, Pt, and other precious metals on the three-dimensional p-CNG skeleton. By monitoring the positive correlation between the metal content and the diffraction intensity of the three-dimensional porous-graphene-phase carbon nitride skeleton, it was determined that the three metals were successfully anchored on the three-dimensional porous-graphene-phase carbon nitride body. Subsequently, the performance, photostability and thermoelectrochemical performance of the hydrogen evolution reaction (HER) were tested. Because precious metals can be used as electron acceptor sites, the effect of electron-hole separation is significantly improved, and it has strong HER activity under simulated solar light (SSL). The test results show that the 3D p-CNG–Pt composite catalyst exhibits better HER activity than the 3D p-CNG–Au and 3D p-CNG–Pd composite catalysts under optimal conditions. This is due to the effective charge transfer of platinum and 3D p-CNG skeletons, which shows better HER kinetic curve linearity and lower catalyst dose consumption and results in better durability. In terms of thermoelectrochemistry, the 3D skeleton exhibits a wider absorption boundary (531 nm) than the 2D skeleton, and the anchored Au, Pd, and Pt significantly improve the photoreaction effect of the 3D p-CNG composite catalyst due to the improvement of the electron transition pathway [Many functional catalysts are used to enhance two-dimensional graphene phase carbonitrides ,141,142. pathway .2 absorption, and significantly improve the activity of the photocatalytic reduction reaction [Wang’s team provided a new approach to the photocatalytic charge transfer pathway. The team used the characteristics of the ordered structure of the metal organic layer to easily obtain active sites and prepared a 1.5 nm metal coordination layer with rGO as an electron mediator. The ultrathin two-dimensional metal–organic layers (MOLs) are distributed on the two-dimensional template constructed by rGO. The synergistic effect and electronic mediation of the two compensate for the gap between heterogeneous catalysts and homogeneous antenna molecules, improve the energy efficiency of photocatalysis and COreaction .2. This study undoubtedly provides ideas and future research directions for supramolecular organic photocatalysis at the level of quantum modification [Although metal-doped photocatalysts have been extensively studied, as described above, the efficiency and effectiveness of photocatalytic hydrogen production have been significantly improved. However, the use of these doped materials is still challenging in many aspects, especially with regard to their impact on the environment. For example, if the material is applied to too many metals, the cost of subsequent waste recycling will be increased. If not handled properly, this may lead to regional heavy metal pollution. This runs counter to the previous idea of improving global energy tensions and environmental crises through in-depth research on photocatalytic technology. Therefore, research on promoting the photocatalytic effect by relying on the characteristics of different dimensions of graphene-based materials is still advancing. Researchers want to improve the photocatalytic effect of graphene composites through the dimension of materials and the introduction of non-metallic elements, such as carbon, hydrogen, oxygen and phosphorus, to reduce the content of doped metals as much as possible, and even not introduce the whole process. Based on the photocatalytic process of perylene bisimide (PBI) supramolecular materials, the addition of zero-dimensional  graphene quantum dots (GQDs) significantly improve the effect of visible light photocatalysis . The smafication .2 under visible light. They reported two ways to narrow the band gap of GQD and explained the mechanism. GQD-Anln-OCH3, GQD-Anln-OCF3 and GQD-Anln-OCCl3 have a Z-scheme structure, and charge separation can promote coupled photocatalysis  bifunctional electrocatalyst is formed by the nitrogen doping and nickel doping of 3D nanoporous graphene, in which nitrogen and nickel have two forms: single atom and cluster. A rechargeable all-solid-state zinc–air battery was prepared by using nitrogen and nickel co-doped np-graphene as a self-made flexible air cathode, PVA gel as an electrolyte, and Zn foil as an anode. As shown in xibility .4 and Fe-N4 Janus structure with distributed self-assembly, in which a planar configuration is formed to coordinate with four nitrogen atoms. The Janus structure on the inner and outer walls of the GHSs separates the ORR and OER active sites. The outer Fe-N4 site plays a major role in the ORR activity, and the inner Fe-N4 site plays a major role in the OER. When Ni-N4/GHSs/Fe-N4 is used as the air cathode, the specific capacity of Ni-N4/GHSs/Fe-N4 can reach 777.6 mAh gZn−1, and the energy density can reach 970.4 Wh kgZn−1, showing excellent bifunctional electrocatalytic activity. The Ni-N4/GHSs/Fe-N4-based zinc–air battery still maintains stable electrocatalytic performance after about 200 h of operation, which is considered excellent cycle stability [The single atoms of nickel and iron are respectively embedded in the inner and outer walls of graphene hollow nanospheres (GHSs) to form a new type of highly active Ni-Ntability .In recent years, antibiotics have been widely used in human treatment, animal husbandry, and aquaculture . HoweverAntibiotics have a negative impact on plants, aquatic organisms, and microbial communities, causing damage to the ecological environment and affecting human health. The common antibiotics contained in wastewater are tetracycline antibiotics, quinolone antibiotics, β-lactam antibiotics, macrolide antibiotics, sulfonamide antibiotics, etc. . As one 3O4 composites formed by adding GO are further improved compared with using Fe3O4 alone. The OFX removal rate can even reach 99.9% complete removal. Compared with the alkaline environment, the degradation rate and ability of OFX is more effective under acidic conditions [It has been found that the removal efficiency and kinetic constant of rGO-Fenditions . After 0nditions .2–Fe3O4 nanocomposite plasma has a good degradation effect. Compared with rGO–TiO2, the addition of Fe3O4 enlarged the specific surface area of the composites, accelerated the separation of electron-hole pairs, and increased the magnetic strength, which made the catalyst easy to separate from water. At the best doping amount of Fe3O4 of 20 wt%, the removal efficiency can reach 98.1%, which is the highest removal efficiency. Other influencing factors include the catalyst dosage, air-flow rate, peak voltage, and pH value, and their optimal values are 0.24 g/L, 4L/min, 18, and 3.2 kV, respectively. When the above conditions are reached, rGO–TiO2–Fe3O4 has the best removal performance. The rGO–TiO2–Fe3O4 still has high catalytic performance after four uses [Using citric acid-modified GO and carboxymethyl cellulose membrane (GO-CMC) to remove antibiotics, the adsorption capacity of OTC, quinic acid (OA), and trimethoprim (TMP) can reach 102.05, 252.68 and 370.93 mg/L, respectively. Antibiotics are deposited on the surface of GO by π-π interactions and cation-π bonds. The citric acid-modified GO-CMC membrane can be reused and maintains stable recyclability after 5 times of recycling, which can remove antibiotics in wastewater . For proour uses .2-based catalytic system is widely considered to remove pollutants in the environment without producing secondary pollutants, which is conducive to environmental protection [2/N-doped porous graphene nanocomposites (TiO2/NHG) is better than that of bare p25 TiO2, TiO2/GO and TiO2/porous graphene frameworks. The results showed that the oxidative degradation rate of TiO2/NHG was affected by the catalyst loading, the initial antibiotic concentration, and the presence of H2O2. The complete mineralization of 25 mg/L of antibiotics was observed within 90 min of irradiation, and the activity level of the TiO2/NHG catalyst did not decrease significantly within three repeated cycles. The complete mineralization of antibiotics can be achieved only by sunlight irradiation within a reasonable time span, which means that the oxidative degradation of antibiotics remains efficient even in the absence of H2O [Heterogeneous photocatalytic technology based on the TiOotection . For cepe of H2O .−1 at pH = 6.0. At the same time, after four absorption cycles, the adsorption capacity of MZs still did not decrease significantly and maintained a relatively stable adsorption activity. MZ materials have been proved to have the advantages of fast separation speed, strong adsorption capacity, reusability, and simple operation in use [3C2, a graphene-layer anchored TiO2/g−C3N4 (GTOCN) photocatalyst was formed by a one-step in situ calcification method. This method of synthesis can not only act on antibiotics but also on another persistent organic pollutant, namely dyes. Under visible light, such as sunlight in daily environments, GTOCN will have highly oxidizing active ·O2 and ·OH, hence offering high-efficiency degradation of tetracycline (TC) and ciprofloxacin (CIP) antibiotics and bisphenol A (BPA) and rhodamine B (RhB) dyes [Magnetic GO/ZnO nanocomposite (MZ) materials offer an excellent adsorption capacity with reusability for tetracycline antibiotics (TCs) in wastewater. The results show that the maximum adsorption capacity of MZ materials for TCs can reach 1590.28 mg gn in use . Based ohB) dyes .3–Fe3O4 nanocomposites. Compared with single WO3 and rGO–WO3 without Fe3O4, rGO–WO3–Fe3O4 has a larger specific surface area and higher transfer rate of photogenerated carriers. Fe3O4 doping does not make the higher the better. With the gradual increase from zero, the TAP removal curve first increased and then decreased. When the Fe3O4 doping amount was 24 wt%, the catalyst dosage of 0.23 g/L obtained the best catalytic performance, and the removal rate of TAP could reach 99.3%. Acidic conditions and the presence of O3, H2O2, and ·OH are more conducive to the catalytic degradation of TAP [The synergistic catalytic removal of thiamethoxam (TAP) induced by pulsed discharge plasma (PDP) was studied by using graphene–WOn of TAP .3N4-MoS2 loading. Perhaps due to the cleavage of functional groups such as amide bonds and peptide bonds, the removal rate of ampicillin by the photoanode reached 74.6% after the system was fully reacted in sewage for 2 h [The three-dimensional (3D) graphene can be designed as an anode to create an enhanced electron and mass-transfer photocatalytic circulation system, which can be used to remove ampicillin in wastewater and to enhance the antibacterial properties of water. It enhances electrons by using a three-dimensional graphene photoelectrode as an anode, a Pt/C air breathing electrode as a cathode, and C for 2 h .2 sponge modified by molybdenum disulfide nanospheres and GO adsorbs organic molecules and provides a multidimensional electron transport path, which has a positive effect on the degradation of advanced oxidation processes (AOPs), especially for aromatic organics. After pilot-scale experiments in 140 L wastewater, it still maintains efficient and stable activity for AOPs. Even after 16 days of continuous experiments, 3D-MoS2 can still maintain a degradation rate of 97.87% in wastewater containing 120 mg/L antibiotics. This is of great practical and economic interest for industrial applications; if the sponge could be produced industrially in large quantities, the cost of treating a ton of wastewater would be only USD 0.33 in the future [The 3D-MoSe future .Ion-doped GO nanocomposites can perform photon absorption, electron transfer, and the generation of active species under visible-light irradiation. For example, an iron oxide/hydroxide N-doped graphene-like nanocomposite has been synthesized by a laser-based method to remove antibiotics from wastewater. The method is shown in One of the main causes of surface water pollution is from the textile industry, where waste from the printing and dyeing process is directly discharged into the water environment without qualified treatment .The incr2), MG consumption may lead to many serious human health issues, e.g., cancer, etc. [−1. The hydrogel complex showed sustainable usability and could still adsorb 91% of MG after three consecutive dye adsorption–desorption cycles [A triphenylmethane cationic dye—Malachite green (MG)—is a common dye in the dyeing process of the textile industry. However, due to the presence of nitrogen  dye from aqueous solution with a maximum adsorption capacity of 270.27 mg g−1.When the reaction environment meets the conditions of temperature  mesoporous structure with a high surface area of 214.75 mng ratio .2·h. Compared with other compositions and doping materials, the nanocomposite membrane with 0.1% w/v GO is superior. When operating conditions reach 0.1 MPa operating pressure, the dye rejection rate can reach 98%. After several tests on the membrane, the flux recovery rate of almost all dyes can be stabilized at 94%, while the removal rate of individual dyes such as methyl orange can reach 95%, and that of Allura red can be as high as 98% [A polyvinylidene fluoride (PVDF)–polyaniline (PANI) and GO mixed membrane was prepared by incorporating PANI–GO as a nano-filler, which greatly improved the antifouling performance and solvent content. The pure water flux through the membrane increased from 112 to 454 mL/mh as 98% .A nanocomposite hydrogel (NCH) formed by chitosan (CS) and carboxymethyl cellulose (CMC) crosslinked-modified GO has a significant adsorption effect on methylene blue (MB) and methyl orange (MO). At pH 7, the adsorption rate of 0.4 g/L CS/CMC-NCH for 50 mg/L MB was about 99%. At pH 3, the adsorption rate of 0.6 g/L CS/CMC-NCH for MO was about 82%. The adsorption capacity of CS/CMC-NCH for MO is 404.52 mgdye/gads, and the adsorption capacity for MB can reach 655.98 mgdye/gads. More importantly, the composite hydrogel has a stable adsorption performance for the dye after continuous use of 20 adsorption–desorption cycles. CS/CMC-NCH also has an excellent effect on the removal of anionic and cationic dyes . The novFor the removal of the crystal violet (CV) dye, it was found that two kinds of nanocomposite hydrogels, acrylamide-bonded sodium alginate (AM-SA) and acrylamide/GO sodium alginate (AM-GO-SA), can be synthesized by the free radical method, and both of them have good adsorption properties for CV. Compared with other influencing factors, the removal efficiency of AM-SA and AM-GO-SA was more dependent on pH, and the maximum single-layer adsorption capacity could reach 62.07 mg/g and 100.3 mg/g .A novel GO/poly (N-isopropylacrylamide) (GO/PNIPAM) composite system removes organic dyes in water by a similar extraction mechanism and undergoes a reversible sol–gel transition at a temperature higher than the lower critical solution temperature. PNIPAM is anchored on the surface of GO to prevent the reduction of GO and inhibit its aggregation, which greatly improves the stability of GO dispersions. Moreover, the dye can be effectively adsorbed and enriched in the gel phase, which is convenient for its separation from water during the extraction process .The rapid development of modern transportation, petrochemical, and marine engineering has accelerated the release of a large amount of oil into the sea and rivers, causing energy loss, destroying the local ecological environment, and seriously endangering the sustainable development of society .The urgeBased on polyimide (PI), a novel zeolitic imidazolate framework-8/thiolated graphene (ZIF-8/GSH) nanofiber membrane can be prepared by electrospinning and in situ hydrothermal synthesis. The membrane has superhydrophobicity/superoleophilicity and can effectively purify oily wastewater. For various oil/water mixtures and water-in-oil emulsions, the separation efficiency of oil and water can reach 99.9% through the action of fiber membranes. More importantly, the film maintains superhydrophobicity without requiring the environment to remain under harsh conditions. Under harsh reaction conditions, such as excessive acid and alkali, long-term contact with salt and corrosive organic solvents, high temperature irradiation, mechanical wear, ultrasonic treatment and other simulated environmental conditions, ZIF-8 @ GSH can still exhibit excellent photocatalytic degradation efficiency. This shows that the membrane has self-cleaning and active antibacterial abilities and can maintain its performance through the mechanical and chemical environment, which makes future industrial applications very promising .3O4/OA/GO-PU) was formed based on a 3D microstructure by linking GO and coating with functionalized oleic acid Fe3O4 nanoparticles. It can be water repellent, with a contact angle of 158°, and has high selectivity in contact with organic solutions and oils. Theoretically, the microstructure polyurethane (M-PU) sponge has a capacity of 80–160 g/g, and it can undergo 15 adsorption cycles. The oil can be selectively extracted from the wastewater, exhibiting excellent recyclability and the ability to be recovered in a static state using an external magnetic field. Compared with the absence of a magnetic field, the increase of M-PU adsorption capacity seems to be driven by magnetic field exposure due to the enhancement of surface-active sites of the M-PU sponge. The continuous collection of kerosene from the surface water while cleaning wastewater with Fe3O4 @ OA @ GO-PU is cost-effective, highly selective, and an excellent recyclable, environmentally friendly oil-spill cleanup option [With the release of a large amount of oil pollution into the water environment, the emergence of reusable superhydrophobic oil adsorption materials are required. A magnetic superhydrophobic polyurethane sponge  remained above 90%. Even without any alkaline and acidic cleaning, it exhibits good separation rate for oil-in-water emulsions and stable antifouling and antibacterial properties [Using phase inversion technology and the dip coating method, a nanocomposite film was composed of polybenzimidazole (PBI), graGO, rGO, and polydopamine (PDA) in a coated and uncoated manner as shown in operties .A novel poly (oxyethylene) graphene oxide-based nanofluid (P-GO-O) prepared as shown in the As shown in 3+ as a crosslinking agent and a spacer layer for insertion; moreover, it stabilizes the SFGO film selection layer and achieves selective molecular transport. The permeability of methanol is 2.9 times higher than that of large-flake graphene oxide (LFGO), and it has high selectivity for three organic dyes. More importantly, the SFGO-La3+ film exhibits at least 24 h of stable stability under hydrodynamic stress, which represents real OSN operating conditions. Through the interfacial polymerization (IP) of low-concentration resorcinol on the surface of the graphene quantum dot (GQD)-polyethylenimine (PEI)-modified polyimide substrate, a new nanocomposite (TFN) organic solvent nanofiltration membrane with a sandwich structure was prepared as shown in the −2h−1MPa−1, and the penetration rate of Rhodamine B from 87.4% to 98.7%. After long-term immersion in pure N, N-dimethylformamide (DMF), it showed superior solubility. After 81 days of storage at room temperature, it was stored at 80 °C for 45 days and then filtered with Bengal Rose (1017 Da) DMF solution at 25 °C for 5 days. There was no scar solute rejection, which proved the antifouling performance during long-term filtration [A small sheet of graphene oxide (SFGO) film for high-performance organic solvent nanofiltration (OSN) applications, using Laltration .Common heavy metals in sewage, such as Cd, Zn, Pb, Fe, Cu, Hg, Ni, Mn, Co, etc., generally exist in trace amounts. Even in very small amounts, heavy metals are considered to be the most harmful, toxic and most widely distributed components in wastewater due to the mobility of the ions .The disc2+ and Cd2+ has excellent adsorption capacity with great potential [In the past, traditional technologies were used, such as non-destructive processes using resins or adsorbents , non-desotential . Becauseotential .2S3-BiVO4 graphene aerogel (SVGA) requires only a simple hydrothermal method, which can provide effective assistance in both the photogenerated electron transfer and photocatalytic ability of SVGA. The results show that removal rates of Cr (VI) and bisphenol A (BPA) using SVGA materials can be infinitely close to 100% after 40 min of adsorption and 120 min of photocatalysis under visible-light irradiation at 420 nm. The harmful Cr (VI) is preserved as low-toxic Cr (III) after photocatalysis on SVGA, and BPA is degraded into CO2 and H2O [The preparation of a Bi and H2O .2SO4 aqueous solution. Reductive self-assembly (RSA), one of the main materials of MFHGs, is cheap and environmentally friendly, so the cost of MFHGs is not high. They have excellent magnetization and large coercivity and can work normally in high-salinity water [Due to the presence of oxygen-containing functional groups and high porosity, 3D magnetic fungal mycelia/graphene oxide nanofibers (MFHGs) can remove Co (II) and Ni (II) from high-salinity aqueous solutions, increasing the ion removal rate. The optimum reaction conditions were as follows: at 323 K and pH = 6.0, MFHGs could remove 97.44 and 104.34 mg/g of Ni (II) and Co (II), respectively, from 2 g/L Naty water .Under aerobic conditions, a novel graphene-like biochar supported trivalent iron (GB/nZVI) to remove Cd (II) and As (III). The main principle of removing As (III) is through oxidation and surface complexation, while the removal of Cd (II) mainly depends on surface complexation. At the same time, the strong synergy between GB and nZVI has a positive effect. The removal ability of GB/nZVI composites was significantly higher than that of pure GB and nZVI under both acidic and neutral conditions. The presence of As (II) significantly promoted the removal of Cd (III) when both ions were present in the same water environment. The maximum removal of As (III) can reach 181.5 mg/g when nZVI is 363 mg/g. The maximum removal capacity of Cd (II) can reach 46.4 mg/g when n ZVI is 92.8 mg/g. It is worth mentioning that the presence of phosphate and humic acid in the coexisting background ions has a reverse inhibitory effect on the removal of Cd (II) and As (III) .h) with different degrees of oxidation were combined with tridentate terpyridine ligand (Tpy) to form GO, GOh, and GO–Tpy as shown in h, and GO–Tpy, GOh–Tpy has the highest adsorption efficiency for heavy metal ions due to the synergistic effect of GO and Tpy components. The maximum adsorption capacity (qmax) of the GOh–Tpy system for Ni (II), Zn (II), and Co (II) reached 462, 421, and 336 mg g−1 at pH = 6, respectively, and showed excellent repair performance, which proved that the GOh–Tpy mixture had an ideal cycle stability, reusability, and easy separation operation [GO and highly oxidized graphene oxide (GOperation .2), benzene, and isopropanol are the three major pollutants that can be commonly found outdoors. Titanium dioxide/graphene hybrid nanomaterials were synthesized by the sol–gel method. Under UV-A irradiation, the presence of isopropanol and benzene will form different free radicals, which improves the removal efficiency under UV-A irradiation. The addition of at least 1.0 wt% of granolol to TiO2 can double the photocatalytic efficiency, and the system exhibits more stability under oxidizing conditions compared with pure TiO [Exposure to air pollution is one of the five major global human-health risk factors. Photocatalytic oxidation is a promising method for the treatment of environmental pollutants. Nitrogen oxides  is at a high concentration, the photodegradation rate of benzene and toluene can reach a 91% oxidation rate, while PIL @ TiO2/m-GO can reach 97% at a low concentration, and the percentage is obtained within 24 min [A multi-ionic liquid (PIL)/TiOn 24 min .A novel high-strength graphene aerogel was prepared by adding tetraethoxysilane (TEOS) to the precursor GO solution, as shown in the 2 began in 1972 and 1979 when Fujishima and Honda used TiO2 as a motor to photocatalyze the reduction of CO2 in water [2 is matched with the valence band and the conduction-band position of the semiconductor photocatalyst, but most of the semiconductors cannot satisfy this requirement; thus, to achieve CO2 reduction and emission reduction in photocatalytic reactions under sunlight, it is necessary to find semiconductors that meet the above conditions.Solar energy will be an important component of future energy improvements for new sustainable development. Research on the photocatalytic reduction of COin water ,215,216.2 has three main steps: (1) the generation of photogenerated electrons by bandgap engineering; namely, the generation of photogenerated charge carriers and the formation of electron-hole pairs; (2) the transfer of photogenerated electrons—this process can be called charge carrier separation and transport; and (3) the reduction of CO2 by photogenerated electrons on the surface.According to the basic reaction principle, the photocatalytic reduction of CO2 emission reduction. Graphene is used as electron acceptor/transporter due to its high power function and good conductivity.Given that electron-hole pairs combine easily and restrain charge separation to a great extent, effective charge separation is the key to achieve large-scale CO2 adsorption through π-π conjugation between graphene and CO2, (iii) activates CO2 molecules, (iv) improves corrosion resistance, (v) enhances surface area and light absorption, which subsequently results in higher photocatalytic activity [In the process of photocatalysis, graphene plays the following roles: (i) reduces photogenerated electrons and hole recombination, (ii) promotes COactivity .2 reduction, the catalyst surface activity is reduced, and the production efficiency is low [Since most catalysts are easy to recombine due to the influence of electron-hole pairs in the process of COy is low . Grapheny is low . Grapheny is low ,221,222.y is low ,226,227.Doping is the most feasible and convenient method to adjust the band structure of graphene from semi-metal to p-type or n-type materials ,229. Pri2O, O2, N2, NO2, PMMA, etc.) will lead to obvious p-type doping. If the heteroatoms are removed from the p-type doping, the p-type doped graphene will return to the state before the original doping [Graphene doping can be divided into n-type doping, p-type doping and p/n co-doping of single-layer or double-layer graphene. The chemical doping of graphene is realized by attaching heteroatoms to the surface of graphene or by replacing C atoms in graphene. For graphene, it is easier to produce p-type doping through surface adsorption . Exposurl doping .Chemical doping can effectively open the band gap of graphene . The Fer2O, N2, O2, and CO2. These small molecules will promote graphene to form p-type doping. We can also open the sp2 bond of graphene by replacing the position of carbon atoms or other atoms and bonding with carbon atoms to form doping. Because graphene can be prepared in large quantities by chemical vapor deposition (CVD), we can add different reaction sources to it at the end of the production, so that some carbon atoms in graphene can be replaced to form lattice doping. For example, under certain conditions, boron atoms can partially replace carbon atoms, forming p-type graphene. Common p-type doping molecules include fluoropolymer, water, N2, NO2, O2, oxidizing solution, B, Cl, and metal [2 on B-doped graphene and double B-doped graphite has strong chemisorption. The strong interaction between single- and double-B-doped graphene composites show that B-doped graphene and double B-doped graphene can catalyze or activate, which indicates that B-doped graphene and double B-doped graphene can be used as effective catalysts for CO2 reduction [As a doped atom, graphene can provide a large number of electrons, which is due to the existence of large π bonds. The electrons in its parallel p-orbitals enter the conduction band, leaving a large number of holes in the valence band, forming an electron-hole pair. The Fermi energy level is close to the bottom of the conduction band. This doping method is p-type doping. In general, graphene has a two-dimensional honeycomb structure, so its surface easily adsorbs some small molecules, such as Hnd metal . Khudaireduction .Individual metals are easy to dissolve in the reaction environment because of their low bulk-binding energies, which have been extensively calculated by Chen et al. In the ORR performance of the 10 metal-doped graphene (M-G) catalysts  they studied, the metal bound to the graphene had higher binding energy, which shows that the M-G catalyst can be more stable compared with samples without metal dopants .In the study by Min et al., different kinds of metal-doped graphene  were found to have different band gaps . The ban2 with a GrN700-CuC catalyst. At the same time, in order to verify that the reduction product methanol is produced by CO2, they replaced CO2 with N2 and found that the methanol content is small enough to be ignored. All the results show that the N-doped graphene catalyst has good chemical stability and can be further applied and developed.As shown in 2 reduction. However, in practical research, it is found that a single-metal material cannot achieve high photocatalytic efficiency, and a graphene heterostructure can effectively solve this problem.As a material with excellent photosensitivity and conductivity, graphene has a good application prospect in the field of photocatalysis and CO2, because the graphene heterojunction effectively reduces the energy band structure of CO2 and can more easily dissociate the C-O bond (750 kJ·mol−1) [2O6 heterostructure can reduce its energy band structure to 0.025 eV. This is because heterostructures in graphene can effectively migrate electrons from the interior to the surface. They are excited to graphene through the electrostatic field, promoting the separation of electron-hole pairs and inhibiting the recombination of carriers. In this way, a large number of electrons can be formed on the graphene surface, and a large number of holes can be accumulated on the heterostructure. Such a good combination can greatly promote charge transfer and photocatalytic efficiency [First of all, we found that the heterojunction can significantly improve the reaction efficiency in the reduction reaction of COJ·mol−1) . Doping ficiency  . In order to obtain materials with more photoelectrons, Tang et al. coated silver nanoparticles on the materials, according to the characteristics of silver nanoparticles with low Fermi energy, and finally obtained more photoelectrons in Cu2O. At the same time, because of the high specific surface area and two-dimensional honeycomb structure of GO after sp2 hybridization, it can adsorb gas better and enhance activation ability by coating a Ag/Cu2O surface. In the end, they concluded from a number of experiments that the ternary heterojunction can effectively reduce the CO2 content in photocatalysis and selectively produce CH4 [2O/graphene/TiO2 nanotube array (TNA) heterostructure as a separate oxidation and reduction catalyst, which uses anode TNA as the substrate, electrodeposits graphene and Cu2O in turn. The results of photoelectrochemical measurements show that the ternary heterogeneous materials display the advantages of each component, improve the photocatalytic performance significantly, and show excellent performance in light absorption and the reduction of electron-hole pair coincidence; in other words, ternary heterogeneous materials are excellent catalysts for photocatalytic reactions [Zhiling Tang et al. developed the ternary catalyst of rGO-coated Ag/Cuduce CH4 . Similareactions .2 and convert it into fuel because of its superior photocatalytic properties when combined with metal oxides.It is concluded from the above-mentioned optimization strategies that the inhibition of electron-hole-to-ground recombination is the key to enhancing photocatalytic efficiency. Graphene-based photocatalytic engineering is an effective way to reduce COGraphene’s broad absorption spectrum is one of the main reasons for its excellent photosensitivity, and its excellent performance in light absorption is an effective way to improve the efficiency of photocatalysis. Li and his colleagues reported that the addition of graphene to Pt-TiO enhanced the light absorption. In this process, finding the appropriate doping stoichiometry is the key to improving the optical absorption efficiency.3N4(PDI/G-CN) nanosheet and demonstrated the potential practicability of an S-type heterojunction in photocatalysis [A great deal of research has been conducted on the preparation of highly efficient heterojunction photocatalysts. Rui Sun et al. obtained the heterojunction of a perylene diimide/Graphene-g-Catalysis .2 reduction [Radovic et al. have found that the transfer of photogenerated electrons occurs through Valery Karpin sites in graphene after doping and that the surface of the doped graphene has more oxygen vacancies, and realignment occurs. The active sites on the surface provide more sites for COeduction .2-modified N-graphene heterostructure catalyst for CO2 reduction for highly selective methane production. Doped graphene itself has excellent photocatalytic performance, and TiO2 also plays an excellent role in synergistic catalysis. Properly designed plasma gold nanoparticles electrodeposited onto TiO2-modified N-doped graphene (ANGT-x) heterostructure catalysts exhibit significant CO2 reduction activity and high methane generation selectivity. Compared with the typical binary Au-TiO2 photocatalyst, the electron consumption rate (Repetron) value of the reduction product of ANGT2 is about 742.39 µ mol g−1h−1,the latter is 60 times more than the former. As far as we know, this is the highest PCO2R rate reported under comparable conditions. These remarkable improvements are attributed to good light selectivity and improved electron transfer dynamics. At the same time, due to the formation of the heterojunction by doping, the components form a seamless interface. Their contact greatly inhibits the recombination of electron-hole pairs and improves the efficiency of charge separation.Khaja Mohaideen Kamal, Rekha Narayan, Narendraraj Chandran, and others studied the synergistic enhancement of plasma gold nanoparticles on a TiO2 reduction. On the premise that the coupling of CO2 reduction and H2O oxidation forms a complete photoelectrochemical cycle, graphene can change the conduction-band potential of semiconductors to form graphene-based composites, which leads to the reduction of CO2. It has been reported that graphene/WO3 nanobelt composites can reduce CO2 to CH4, in which graphene improves the conduction band of WO3 in the composites, while single WO3 inherently limits the reduction of CO2.The combination of graphene and semiconductors as a synergistic heterogeneous composite can improve the efficiency of photocatalysis or electrochemical COThe main preparation methods of graphene matrix composites include physical coating, CVD, electrophoresis, and electrodeposition. The physical coating method is to attach the available graphene or graphene-based composite materials to the target materials without changing their physical and chemical properties. The CVD method has been briefly explained in the above section on chemical doping. Electrophoretic deposition (EPD) is a general processing technology for depositing graphene with controllable thickness and uniform structure on a wide range of substrates ,248,249.2-rGO nanocomposites developed by Liu et al. They used GO and TiO2 nanoparticles as starting materials to realize the efficient photocatalysis of GO composites through simple and relatively general methods.Herein, we show you the preparation method for TiO2 efficiently simply by using components as photocatalytic materials. Metal–organic framework (MOF)/GO composites were prepared for CO2 capture under flue gas conditions by using the method of Mégane Muschi and Sabine Devautour-Vinot, and its performance greatly exceeds that of pure components. Based on the microporous water-stabilized MIL-91(Ti), a series of CO2-capture composites were prepared by in situ and post-synthesis methods. It was observed that 5 wt% GO in situ composites exhibited semi-conductive behavior, whereas the composite was insulating, even though the GO content was high (20 wt%). Therefore, compared with pure MOFs and post-synthesized materials, this composite material absorbs microwave radiation more effectively. Finally, Muschi and Devautour-Vinot reported that CO2 desorption under microwave irradiation is faster than direct electrical heating on MOF/GO in situ materials, paving the way for energy-efficient microwave-swing adsorption processes in the future [It is difficult to reduce COe future .2 and the cost-effective production of 3D graphene. In many reactions, in order to solve the problem of building up micro-scale 3D graphene materials, it is necessary to form alkali metals and CO2 graphene at the same time and use them as original templates. Etching graphene by CO2 is the key project to control the formation of porous surface structures, so it also provides a good scheme for constructing various excellent 3D graphene materials [Graphene itself is a two-dimensional honeycomb material. It is precise because of its structural characteristics of a high specific surface area, which greatly increases its reaction efficiency. Zhuxing Sun and Yun Hang Hu proposed several 3D structure graphene materials that can reduce the accumulation of graphene sheets and help improve the photocatalytic efficiency of graphene-based materials. They found that the exothermic reaction between an alkali metal and inorganic carbon compounds provides an ideal solution for the efficient utilization of COaterials .2 emissions. There are many types of materials in this field, but they are mainly based on graphene for the mixing of three or other components. Barbara Szczęśniak et al. have studied three-component GO/ordered mesoporous carbon/metal organic matrix composites to address the need for expensive organic binders in the field of composites, and they found that the three-component composite also contributes to the formation of MOF crystals during air raids on mesoporous networks and CO2 recovery [The current research on graphene-based composites is aimed at reducing COrecovery .2” hybridization, which greatly enhances its structural strength and flexibility. Based on this hybrid, graphene “sp2” hybrid-connected carbon atoms can be tightly stacked into a single-layer two-dimensional honeycomb lattice structure. Bandgap engineering can effectively adjust the bandgap of graphene, and it plays a role as a charge-transfer carrier to enhance the efficiency of electron transfer and to increase the reduction rate of CO2 [Graphene has a strong s bond between its two carbon atoms due to its “spe of CO2 .The translational symmetry of the original graphene is broken, that is, when two equivalent atoms in the original cell become unequal, a band gap will be generated. The experiment of introducing a band gap into the original graphene includes growing graphene on some substrates, applying an external bias voltage, generating graphene in the form of narrowband graphene, and perforating graphene to form a “graphite nanonet” ,254.Through a lot of research on graphene bandgap engineering ,261,262,It has been proved by experiments that if nanopores or molecularly modified graphene are introduced into the original graphene, the required translational symmetry can be removed, thus opening the band gap. Doping some elements into graphene can open the band gap. For example, the hydrogenation of graphene can effectively adjust the band gap of graphene. In addition, some graphite intercalation compounds (GIC) are outstanding in inducing superconductivity .2” and “sp3” hybridization. Therefore, the proportion of operating hybrid-bonding atoms can effectively adjust the broad band gap of GO, transforming it from an insulator to a semiconductor and into a metal similar to graphene. The oxidation functional groups around GO can operate through H3PO4. The amount of H3PO4 is the key to the operation affecting the oxidation functional groups, which leads to a tuned band gap that is well aligned with the CO2/CH3OH redox potential  and shows an improved activity of CO2 photoreduction to methanol. The conversion of CO2 to methanol requires stretching the band gap of GO so that there is a CH4 production orientation in the CO2 conversion. After much research, it has been found that there are many oxygen groups on the surface of GO, which can effectively stretch the band gap of GO. This stretching regulates the oxidation and reduction potential of CO2 to match the valence band and the conduction band and promotes the generation and excitation of photogenerated electrons, which can migrate to the surface more effectively and induce CO2 reduction.At the same time, because the volatile organic compounds adsorbed on the surface of the catalyst combine with the lattice oxygen on the surface of the catalyst, the catalyst surface generates oxygen holes and is reduced, and the catalyst is oxidized by filling the oxygen vacancies with the dissociated adsorbed oxygen. The resulting graphene derivatives, such as GO and rGO, have the characteristics of insulators and similar semiconductors in terms of photocatalysts, resulting in wide band gaps. GO has a limited band gap due to the two-dimensional grid generated by its “sp2 can separate the electron and hole more effectively and keep them in different positions. Tang and colleagues have also demonstrated that graphene-coated metals exhibit rapid CO2 reduction over a longer period of time [Sokal reported on the bandgap engineering of graphene. We know that photocatalysis produces photogenerated electrons, while doped graphene exhibits better charge separation properties. In his paper, Sokal pointed out that the graphene doped with TiO of time .In order to effectively adjust the band gap structure of graphene, Wu et al. calculated the energy band structure of polycrystalline graphene through the density functional theory (DFT). The results showed that even under the condition of external stress, the grain boundaries (GBs) with symmetrical polycrystalline graphene still have zero band gap, while some asymmetric GBs can also open the band gap, which can be adjusted by external stress . The disGraphene and its derived materials are functional materials that have emerged in recent years. They have also been involved in a series of breakthrough discoveries in the field of photocatalysis and pollutant degradation and have spawned the creation of many new photocatalytic materials and applications. So far, many of their advantages have been exploited and utilized by people, and there will be more excellent potential applications in the future. However, there is no denying that graphene also has some shortcomings to be overcome, mainly involving the following aspects:2 and to obtain chemical fuel–metal composite graphene materials similar to CH4 that can be used. However, as a new material, at the environmental level, the economic cost and environmental resource cost of using precious metals to improve the photocatalytic effect are still huge. If some metals are not properly treated, this may cause pollution to the environment and indirectly increase the cost of the subsequent treatment of materials. Metal–graphene composites with low cost and high photocatalytic energy efficiency remain to be found. TiO2 can efficiently utilize ultraviolet light. Although many TiO2 composite graphene materials can expand the range of the photocatalytic reaction light wave, the effect still has a large room for improvement. Making full use of the visible-light band will greatly improve the photocatalytic energy efficiency. In graphene bandgap engineering, the band gap can be opened by reducing the size of the graphene material [(1) Graphene semiconductor materials have been deeply studied in the field of photocatalysis, and they have shown good photocatalytic material properties when combined with many precious metals. They can reduce the bandgap energy and improve the electron-hole yield. They are a good choice to reduce the greenhouse gas COmaterial . This me2 absorption rate, water decomposition efficiency, etc. and significantly improve the photocatalytic effect. Furthermore, there will be no environmental disadvantages of noble-metal composite graphene photocatalytic materials. However, to be economically viable, researchers need to continue to push for lower material costs so that they can be produced on a large scale and use solar energy efficiently. At the same time, there are also some problems to be addressed in the construction of heterojunction structures by organic non-metallic graphene materials. For example, the existence time of two carriers excited by quantum light is short and the photocatalytic efficiency is low, and it is difficult to avoid agglomeration when graphene nanomaterials are introduced. The reaction site of photocatalysis is not positively correlated with the amount of material input. According to the semiconductor properties of graphene, the development and production of highly active graphene-based photocatalysts can be further studied. For different types of graphene-based materials , their electrical properties may have unexpected effects in their applications. At the same time, the application of graphene-based composites in photochromic or electrochromic fields is not mature. Metal oxide-based composite graphene materials or glass-fiber composite graphene may make full use of the semiconductor properties of graphene to participate in the redox process of electrochromic materials and to promote the development of products such as “smart glass”. Furthermore, in catalytic reactions, due to the easy recombination effect of electron-hole pairs, we need to introduce heteroatoms to adjust the band structure of graphene and to reduce the recombination rate of electron-hole pairs. For different types of doped graphene, we have made a detailed overview of metal-doped graphene and non-metal-doped graphene and have given certain conclusions in terms of their basic electronic structure, catalytic active site, and morphology. However, the structural characteristics and functions of doped graphene still need further discussion and research.(2) By constructing two-dimensional and three-dimensional graphene composites, or by constructing porous materials, the high surface-area ratio, optical properties, and mechanical structure stability of graphene can be maximized. These characteristics can increase the photocatalytic reaction area, CO(3) The use of graphene for pollutant degradation has given rise to more graphene-based composites for environmentally friendly cleaning purposes or to enhance the performance of graphene. However, most forms are just composite materials, composite membranes, composite hydrogels, etc., and few become a green and clean treatment system. They have shown good performance in the laboratory, and some can even achieve a 100% removal rate. They also show good recyclability after an adsorption cycle and will not cause secondary pollution to the environment. However, most of them only have good adsorption for individual pollutants, and the removal efficiency for most of the pollutants not mentioned in the discussion are still unknown. In addition, it is also necessary to consider whether the laboratory simulation environment or sampling can fully match the real environment. The environment of different regions is also under different conditions. How to carry out the next industrialization or commercialization step is still a question mark. The cost of material manufacturing or cleaning system construction is one of the issues we need to consider. Nonetheless, if there is a better application than the current choice, that would be a small success.(4) Some defects of graphene-based photocatalyst lead to its low recycling rate, which is rarely considered in most of the current literature. For example, the synthesis of N-doped graphene-based photocatalysts will produce vacancy defects at the same time, which significantly affects the activity of photocatalytic materials. For environmental protection and sustainable development, how to maintain the stability and service life of graphene-based photocatalysts is a direction worthy of study.2 reduction rate. These methods include adding graphene to the substrate, applying an external voltage, producing graphene in the form of narrowband graphene, and using “graphite nanogrids”. The specific graphene band gap provides enormous room for progress in photocatalytic reactions and will be further expanded and developed in the future field of photocatalysis. Single-layer pure graphene sheets lack hydrophilic functional groups, and the preparation of semiconductor/pure graphene composites is extremely challenging. At the same time, as a 2D material, it is still worth exploring how to achieve large-area interface dynamics with other non-2D materials or to load various components to achieve charge separation in space.(5) Graphene has become an important photocatalytic material in the 21st century. In this article, we discuss in detail the bandgap engineering for constructing graphene, which can fully utilize its role as a charge carrier and improve electron transfer efficiency and CO(6) Studies suggest that cytotoxicity mainly depends on the physical and chemical properties of nanomaterials. Surface-doped chemical or biological molecules will also affect the expression of properties to some extent. Nowadays, many graphene products exist in the market with smart devices and sensors, which also creates a problem. Graphene-based materials have toxic effects. When put into use, graphene nanoparticles have a potential risk of exposure to air, which will cause certain irritation to the human body and affect health. In order to give full play to the commercial value of graphene nanocomposites in practical market applications, more in-depth research still needs to be conducted in this area.