Sarcoidosis is a heterogeneous disease with various treatment indications. Although it affects mainly the lungs, sarcoidosis can affect every organ, especially when the disease course is chronic and protracted. Regular patient follow-up is recommended for early recognition of active, ongoing organ-specific granulomatous inflammation to avoid progression to irreversible fibrosis. In this review, we elaborate on treatment indications and various anti-sarcoidosis regimens proven useful in clinical trials. We also review specialized treatment of specific disease manifestations, with a focus on cardiac sarcoidosis. We also report on treatment for special conditions such as fatigue and small fiber neuropathy. Treatment for sarcoidosis is an emerging landscape, with new data complementing the existing knowledge. Cardiac sarcoidosis (CS) occurs in 5% of all sarcoidosis cases, but autopsy and imaging studies reveal clinically silent CS in 25% of cases in the United States.3 CS manifests with atrioventricular blocks, arrythmias, heart failure, and sudden cardiac death, accounting for up to 25% of total sarcoidosis deaths; therefore, prompt recognition and treatment is crucial.4 CS affects all races, has a mean age presentation of 50 years, and may be isolated without evidence of extracardiac sarcoidosis in 25% of those who have it.4 In this review, we address the principles and indications of sarcoidosis treatment, regimens and disease-modifying drugs, and treatment of special conditions.Sarcoidosis is a multisystem granulomatous disease of yet unknown etiology. It has great predilection for the lungs, but multiorgan involvement is common, especially when the disease course is chronic and protracted. Timely recognition and treatment is important as inflammation may progress to fibrosis, leading to irreversible organ damage. Older as well as recent guidelines for follow-up include identification of symptoms, history and physical examination, pulmonary function testing, and blood tests .5 Also, certain disease manifestations  may be treated only locally. Conversely, a recent British Thoracic Society report states that a significant proportion, up to 30%, of patients develop severe and worsening chronic disease requiring ongoing systemic treatment. Mortality is significant among this subgroup of patients, ranging up to 25%.6Not all sarcoidosis patients need systemic immunomodulatory treatment. This variation occurs because in roughly 30% of cases, the disease may subside by itself without ever being treated.2 In other words, treatment is warranted when there is danger of permanent debilitating organ damage or dysfunction with associated morbidity and/or a significantly compromised health-related quality of life on patient-reported outcomes.6 Thus, the goal of treatment is to prevent irreversible evolution of active granulomatous inflammation to fibrosis.7 Disease activity has to be demonstrated before initiation of treatment because already established organ dysfunction should not be treated; disease activity is not sufficient by itself for treatment initiation when organ dysfunction is absent or mild.The decision to treat with disease-modifying agents requires symptomatic, ongoing, and gradually worsening organ involvement (pulmonary or extrapulmonary) as well as certain asymptomatic but significant extrapulmonary manifestations, namely CS, neurosarcoidosis, posterior uveitis, and hypercalcemia.9 Isolated CS may be diagnosed clinically in the absence of cardiac and extracardiac histology when positive PET scan combines with clinical features with or without positive CMR.10Diagnosis of CS with high probability requires abnormal findings in electrocardiogram and/or Holter monitoring and/or echocardiography with abnormal advanced imaging features at cardiac magnetic resonance (CMR) and/or cardiac fluorodeoxyglucose positron emission tomography (FDG-PET).12 The ideal regimen and medication doses in sarcoidosis are not always straightforward, because randomized double-blind placebo-controlled trials are generally lacking in sarcoidosis due to disease complexity, heterogeneity, and ethical considerations to withhold established treatments (with corticosteroids). Table 1 summarizes a treatment algorithm of CS.14 FDG-PET seems to be useful to monitor active myocardial inflammation.15 Treatment has not shown to alter the natural course of the disease longitudinally, as granulomas often recur or progress. The most efficient drug against sarcoidosis is undisputedly corticosteroids. The other two categories of drugs with anti-inflammatory effect are antimetabolites and biologic agents.Recent studies have identified key risk factors for increased mortality in pulmonary sarcoidosis, including decreased diffusion capacity of carbon monoxide (DLCO), presence of pulmonary fibrosis in high-resolution CT, and pulmonary hypertension.20 Note that oral corticosteroids may not have an effect on pulmonary physiology as expressed by forced vital capacity (FVC) and diffusing capacity for carbon monoxide. Furthermore, inhaled corticosteroids, commonly used, have proven ineffective in clinical trials.21Corticosteroids remain the mainstay first-line treatment of sarcoidosis. They have been proven to improve overall disease control, symptoms, quality of life, and pulmonary radiology and/or delay disease deterioration in patients with symptomatic pulmonary sarcoidosis. These effects are short-term, lasting for a period of 1 to 2 years, and fade after treatment withdrawal.24 In recent studies, these relatively moderate doses are shown to manage sarcoidosis manifested as acute disease or as flares of chronic disease, and they are currently recommended by major societies  as an initiation dose with specific exceptions.14 These guidelines consider the significant toxicity of treatment with corticosteroids associated with both cumulative dose and duration of treatment. Common side effects including weight gain, diabetes, glaucoma, osteoporosis, and depression have been frequently observed in sarcoidosis patients.25Studies show that an initiating dose of prednisone at 20 mg daily is not inferior to higher doses in clinical efficacy, control of the disease, physiology, or quality of life parameters.When initiating corticosteroids in a patient with sarcoidosis, close follow-up every 3 months is mandatory. The initial dose is tapered after 3 to 6 weeks, usually by 5 mg, targeting a maintenance dose of 5 to 10 mg of prednisone by approximately 6 months after initiation of treatment. The maintenance dose is required by the majority of patients for a period of 6 to 24 months.7Based on existing literature, several principles apply when considering treating pulmonary sarcoidosis with corticosteroids: (1) acute disease and flares of chronic disease require the same prednisone doses, (2) the chronic maintenance dose should be the lowest possible, and (3) treatment with corticosteroids should be fairly prolonged to allow clearance of the etiologic antigen and adequate suppression of granulomatous reaction.Decision to discontinue corticosteroids is based on disease activity and end organ damage. When adequate control of the disease is accomplished, they should be tapered off. Optimal duration of treatment is not known. Factors that may facilitate decisions in clinical practice are the appropriate selection of high-risk cases, PET-CT scan, and quality of life parameters. Up to 70% of patients experience sarcoidosis relapse during corticosteroids tapering or after treatment withdrawal. Relapses are treated with the same corticosteroid dose as in acute disease.26Addition of a second anti-inflammatory agent is deemed necessary when disease is severe and continued, when serial relapses occur, when corticosteroids are unable to be tapered below 10 to 15 mg of prednisone, when toxicity is significant, and when disease does not respond to corticosteroids.29 MTX has also shown improvement in radiology and in FVC but only in observational or retrospective studies.29 Additionally, MTX has proven effective in neurosarcoidosis, cardiac disease, skin, eye, and disrupted calcium metabolism.1 It is given at a total dose of 15 mg weekly, divided in one or two doses. The most common side effects are blood (cytopenias) and liver toxicities, so these parameters should be monitored closely. To prevent bone marrow toxicity, concomitant treatment with folic acid is imperative. Less than 10% of patients have to stop MTX because of toxicity, and relapses after MTX withdrawal may occur.28 When initiating MTX, males and females of child-bearing age should be warned to prevent fertility due to fetal toxicity during pregnancy. Based on the existing evidence and acceptable toxicity profile, MTX is the recommended first option for a steroid-sparing second-line agent when treating sarcoidosis.26The most commonly studied second-line agent in sarcoidosis is antimetabolite methotrexate (MTX). MTX has exhibited a higher efficacy rate among second-line options managing disease control and steroids tapering in about 65% to 85% of patients with persistent pulmonary sarcoidosis.30 However, these data come from retrospective or observational studies only. Additionally, AZA has significant side effects, mainly gastrointestinal issues, myelodysplasia, malignancies, and secondary infections, with treatment cessation more frequent than MTX. Recent European Respiratory Society (ERS) guidelines made no recommendation for its use as a steroid-sparing agent in sarcoidosis.14Azathioprine (AZA) is a second antimetabolite that has long been used for rheumatic and hematologic diseases and historically has been used in sarcoidosis. Its efficacy is considered less than that of MTX, ranging between 20% to 80%.32 Leflunomide is typically used when a need arises for a second agent with a better safety toxicity profile than MTX. However, leflunomide has adverse effects, most significantly interstitial pneumonia and peripheral neuropathy.34Leflunomide is a cytotoxic drug used in rheumatoid arthritis. Small series have shown efficacy of leflunomide at a dose of 10 to 20 mg daily in pulmonary and extrapulmonary sarcoidosis to improve pulmonary physiology, quality of life, extrapulmonary organ response, and as a steroid-sparing agent.35 HCQ has shown efficacy in cutaneous sarcoidosis and hypercalcemia.37 In these conditions, it is usually given as an adjunct to low-dose corticosteroids or monotherapy. One randomized trial showed some efficacy in pulmonary sarcoidosis and physiology.38 Considered less potent than MTX or other second-line agents, HCQ may be considered in refractory cases when drug toxicity is significant and in combination with one or two other drugs.Chloroquine and hydroxychloroquine (HCQ) are antimalaria drugs used to treat sarcoidosis. Recently, HCQ is used more often due to its lower toxicity profile, although retinopathy remains a significant concern, prompting ophthalmology evaluation upon symptoms.41 Its specific position in the treatment pyramid, likely as a second-line agent, must be further elucidated.Mycophenolate mofetil (MMF) is a powerful inhibitor of lymphocyte proliferation, used to prevent allograft rejection after transplant. Used in various rheumatic diseases, its role in sarcoidosis remains unclear. Retrospective studies showed that MMF has a steroid-sparing effect in chronic sarcoidosis and neurosarcoidosis but is probably less effective than other second-line agents (mainly MTX), with higher relapse rates and a more favorable toxicity profile.43 Infliximab is further proven effective in lupus pernio (efficacy 77%), cutaneoussarcoidosis, and neurosarcoidosis .45 Clinicians must be aware of side effects, ie, infections and tuberculosis.47 Adalimumab may be an alternative in case of infliximab intolerance, as shown (at least partly) in small open-label studies.48 Conversely, neither golimumab nor ustekinumab (anti-IL12/23) showed efficacy in refractory pulmonary sarcoidosis in one randomized trial.49Anti-tumor necrosis factor-α (anti-TNF-α) agents are considered effective third-line drugs in sarcoidosis  by blocking TNF-α, a significant cytokine in granulomatous inflammation. In particular, infliximab (and biosimilars) have shown improvement in FVC in two double-blind randomized studies and was granted a conditional recommendation for use in refractory pulmonary sarcoidosis under CS with or without a second-line agent.52 Rituximab is an anti-CD20 B-lymphocytes antibody that has shown partial efficacy in small case series of advanced pulmonary, eye, and neurosarcoidosis, with a favorable tolerance profile, and may be considered a third-line option.53 Antimycobacterial treatment (CLEAR regimen) for 4 months failed to demonstrate clinical or physiological improvement in chronic pulmonary sarcoidosis.54 Repository corticotropin injection (RCI) was approved in the 1950s for sarcoidosis. Originally considered a steroid analog, RCI may have additional immunological properties and a steroid-sparing effect, although its action is currently limited.55 Janus kinase inhibitors are a drug family recently introduced in sarcoidosis treatment. Among them, tofacitinib showed 60% steroid-sparing efficacy in chronic sarcoidosis in a small proof-of-concept study.56 An overview of drugs used, dosages, and respective monitoring events, with a focus on CS, is presented in Table 2.Various other drugs have been tested in sarcoidosis. Phosphodiesterase inhibitors, pentoxifylline, roflumilast, and apremilast have shown to reduce disease flares, improve quality of life, and improve cutaneous disease, respectively, in small studies.Depending on organ involvement, extrapulmonary sarcoidosis may warrant local treatment, systemic treatment escalation, or multimodality interventions.57 Continued disease should be treated with an additional agent. Hydroxychloroquine and methotrexate are currently used and have shown efficacy in small studies.58 Randomized studies provide support for the use of infliximab in severe skin disease.59 Thalidomide, on the other hand, is proven ineffective compared with a placebo in skin sarcoidosis.60Cutaneous sarcoidosis should initially be treated with local or intralesional corticosteroid injection. Cosmetically important disfiguring lesions (such as lupus pernio) should be treated with oral corticosteroids to achieve control in two-thirds of cases.61 Mycophenolate mofetil and infliximab may be used as well, depending on course and individual toxicities.Anterior uveitis should be treated locally with steroidal eye drops. Posterior uveitis, however, carries risk for blindness and requires systemic treatment, which includes corticosteroids and/or methotrexate in the majority of cases.36 Osteoporosis should be treated carefully in sarcoidosis, as exogenous vitamin D supplementation may lead to hypercalcemia and is only indicated when 1,25(OH)2 vitamin D levels are normal or reduced. When 1,25(OH)2 vitamin D is elevated, osteoporosis is treated with bisphosphonates or denosumab.62Hypercalciuria is treated initially with dietary dairy and restricted sun exposure while hypercalcemia requires systemic treatment. Corticosteroids and/or HCQ are effective in treating hypercalcemia, the latter as sole treatment particularly in cases of unacceptable corticosteroids toxicity.65 When no indication for ICD exists, performing an electrophysiology study is reasonable. Anti-arrhythmic drugs, pacemaker placement in high A-V blocks, and catheter ablation have been of modest value.66Treatment of CS is two-fold. First, based on current guidelines and cardiology consultation, patients at increased risk for sudden cardiac death should be recognized and given an implantable cardioverter defibrillator (ICD), as in all arrhythmiogenic cardiomyopathies. Such patients include those with episode of arrest, left ventricle ejection fraction (LVEF) ≤ 35%, and sustained ventricular tachycardia but also when LVEF is > 35% along with certain physiological or functional features.70 Ongoing studies are underway to evaluate prospectively the impact and dose of corticosteroids in CS . Regarding second- and third-line agents, functional benefit is shown with MTX, MMF, infliximab, and adalimumab.74 In most of these studies, adding a second agent was superior to treatment with corticosteroids alone. Anti-TNF agents were not associated with heart failure deterioration in these studies of CS patients. Unanswered questions remain as per the duration of treatment, the value of adding a second agent from the beginning or later in the course of the disease as well as the management of clinically asymptomatic  cardiac involvement.75 FDG-PET seems a promising biomarker to serially evaluate cardiac inflammation and response to treatment.15Second, patients with clinically relevant cardiac sarcoidosis should initiate anti-inflammatory treatment with corticosteroids. Studies have shown long-term benefit of early initiation of immunosuppressives in CS. Corticosteroids in particular have shown survival and functional benefit, albeit not in randomized trials; lower doses of prednisone (no more than 30 mg) are not inferior to higher doses and are preferred.76 When SAPH is suspected, right heart catheterization is necessary for confirmation and differentiation of multiple SAPH etiologies . Precapillary SAPH carries a 3-year mortality of 30%. Worse outcomes relate to reduced DLCO < 35%, reduced 6-minute walk distance < 300 m, and preserved FEV1/FVC ratio.77 In a small series, epoprostenol and combined ambrisentan with tadalafil showed hemodynamic and functional improvement.79 As to randomized trials, bosentan improved pulmonary hemodynamics at 4 months of treatment, while riociguat significantly delayed time to clinical worsening and improved exercise capacity at 1 year of treatment.81Sarcoidosis-associated pulmonary hypertension (SAPH) is encountered in 5% to 20% of sarcoidosis patients. SAPH along with pulmonary fibrosis constitute an advanced sarcoidosis phenotype, ie, sarcoidosis with a risk of significant loss of organ function or death.12 Transplant referral is indicated when sarcoidosis progresses to respiratory failure despite treatment. Transplant has been performed in patients with fibrosis or obstructive or mixed defects with or without pulmonary hypertension. Ensuing 5-year survival rates were 69%, with age and fibrosis being the worst prognostic factors.82Pulmonary fibrosis extending > 20% of the lungs in high-resolution CT implies advanced disease with high mortality risk.83 A study exploring pirfenidone in fibrotic sarcoidosis is currently underway.Antifibrotic treatment with nintedanib in sarcoidosis with pulmonary fibrosis has shown to ameliorate vital capacity decline, as it did with other progressive fibrosing interstitial lung diseases, in the IN-BUILD trial and may be considered pretransplant.85 Although data are derived from retrospective studies and meta-analyses, they support initiation of corticosteroids versus no treatment, with efficacy rates of corticosteroids alone up to 70%.85 The dose usually administered in clinical practice is prednisone ≥ 0.5 mg/kg daily. A second-line agent will probably be required in continued or relapsing disease, with MTX exhibiting superiority versus MMF, azathioprine, and HCQ (response in 55-70% of cases).86 Lastly, about a third of patients with neurosarcoidosis may require a third-line agent concomitantly. Infliximab is mostly efficient as shown in two studies and less toxic than cyclophosphamide, but relapses tend to occur after treatment discontinuation.87Occurring in 5% to 20% of sarcoidosis, neurosarcoidosis manifests mainly as cranial nerve palsy, parenchymal masses, hydrocephalus, or aseptic meningitis and is associated with a 10-year mortality of 5% to 10%.Figure 1 depicts lines of treatment with available regimens and, on the right-hand side, specific considerations in advanced disease.88 Inspiratory muscle training, a component of pulmonary rehabilitation, may add benefit.89 Pulmonary rehabilitation should be offered in sarcoidosis, as with all interstitial lung diseases. Dexmethylphenidate hydrochloride and armodafinil improved fatigue in 10 and 15 patients with sarcoidosis, respectively, but their use is restricted by side effects such as insomnia and anxiety.91 Lastly, in a randomized trial of sarcoidosis subjects without indication for immunosuppressant treatment, 1 mg dexamethasone daily for 12 months improved fatigue parameters along with serum inflammatory markers; however, this intervention needs confirmation.92Fatigue affects ≥ 60% of patients with sarcoidosis, compromising quality of life, yet it is not directly related to disease activity of the granulomas. Fatigue may be multifactorial due to diabetes, thyroid disease, sleep apnea, depression, and neuropathies. Interventions to alleviate fatigue include pulmonary rehabilitation, neurostimulants, and low-dose corticosteroids. Pulmonary rehabilitation has shown in several studies to improve physical activity, exercise capacity, or just the levels of fatigue.93 Often under-recognized, diagnosis requires large fiber disease exclusion and is facilitated by skin biopsy and sudomotor testing.94 Since there is no established treatment, palliative treatment on a case-by-case basis may include tramadol, anticonvulsants, topiramate, gamma-aminobutyric acid analogues, and intravenous immunoglobulin.95Small fiber neuropathy relates to many diseases, is characterized by debilitating neuropathic symptoms—mainly pain and dysautonomia—and occurs in up to 60% of sarcoidosis patients.Treatment of a patient with sarcoidosis should take into account not only physiologic impairment of the organ but also quality of life and patient-reported outcomes. Corticosteroids, the first-line treatment for acute and chronic disease, should be employed at the lowest affordable dose. To allow this, steroid-sparing agents, in particular methotrexate, are useful and effective. Infliximab, among anti-TNF agents, is effective in refractory pulmonary, cutaneous, and neurosarcoidosis. Patients with advanced disease, pulmonary fibrosis, pulmonary hypertension, cardiac sarcoidosis, and neurosarcoidosis should be thoroughly identified and treated accordingly. Fatigue and small fiber neuropathy impose significant burdens to patients, and efforts should be made to relieve them.Treatment goals in sarcoidosis are preventing permanent end-organ dysfunction and preserving quality of life.Corticosteroids remain the first-line treatment, although with significant cumulative side effects.Second- and third-line agents may be used in refractory or relapsing disease or when corticosteroids cause unacceptable toxicity; methotrexate and infliximab have shown important efficacy with acceptable safety profile in cardiac sarcoidosis.Advanced sarcoidosis refers to high mortality disease manifestations  and necessitates treatment.Cardiac sarcoidosis requires immunosuppressive treatment and recognition of patients at risk for sustained arrythmias, which have to be managed thoroughly.Long-term maintenance therapy remains controversial.


Carbon nanoelectrodes with nanogap are reliable platforms for achieving ultra-small electronic devices. One of the main challenges in fabricating nanogapped carbon electrodes is precise control of the gap size. Herein, we put forward an electroburning approach for controllable fabrication of graphene nanoelectrodes from preprocessed nanoconstriction arrays. The electroburning behavior was investigated in detail, which revealed a dependence on the size of nanoconstriction units. The electroburnt nanoscale electrodes showed the capacity to build molecular devices. The methodology and mechanism presented in this study provide significant guidance for the fabrication of proper graphene and other carbon nanoelectrodes. An approach for the efficient fabrication of graphene nanoelectrodes through the combination of dash-line lithography and electroburning is demonstrated in detail. For instance, electron-beam (e-beam) lithography, as a principle patterning method, can achieve a resolution of sub-50 nm and even sub-10 nm with the aid of specific resists or equipment,9,10 which is, however, still far from the atomic scale. Therefore, the key point of a fabrication strategy is to produce a target nanostructure under patterning precision. In this regard, different kinds of methodologies, including ion/electron beam etching,11,12 selective plasma etching,1,2 and electroburning,3,13,14 have been developed to fabricate nanogapped carbon electrodes. Among them, electroburning is a widely applied method with the advantage of simplicity, controllability, and a lack of dependence on special equipment. In addition, electroburning benefits from the extra capability to control the formation of uncut graphene nanoconstrictions or cracked nanoelectrodes by controlling the burning degree. Hereinto, the former has been applied in the investigation of quantum effects15–17 and the fabrication of functionalized devices,18–20 whereas the latter acts as source/drain electrodes for molecular electronic devices, as discussed above.Nanogapped carbon electrodes are pairs of extremely close carbon materials such as carbon nanotubes or graphene. Because of their advantages including easy chemical processing, strong organic material affinity, low atomic mobility, high carrier mobility, and low screening of the gate electric fields, nanogapped carbon electrodes have attracted extensive interest and have been widely applied in molecular electronics2 Compared to a single unit, they have more potential binding sites and a higher possibility in an array to find a unit with a suitable interval for particular molecules that is beneficial for molecular bridging. This method is described in detail in the Experimental section as well as in literature  process was transferred to silicon wafers with a layer of thermally-grown 300 nm SiO2. Then, graphene was tailored into a 40 μm wide ribbon by a standard photolithographic and selective oxygen reactive ion etching (RIE) method. Metallic electrodes (Cr 8 nm + Au 60 nm) were further thermally evaporated on graphene as source and drain electrodes. A 5 nm wide dash line (d1) and spaces (d2) was patterned on a polymethylmethacrylate (PMMA) mask by a standard e-beam lithographic process. Oxygen RIE was applied to selectively etch graphene from the dash-line windows. The shape of the etching holes (r), which mainly results from the radius of the electron beam, the corrosion of resist development, and the etching of RIE. It is worth noting that for each unit, graphene is processed into a nanoconstriction if 2r < d2 .terature .2 In genash line  with altng holes  inset in 2r < d2  and a gr  were immersed in acetic acid for 30 min at room temperature to remove copper oxide and other impurities. High-quality single-layer graphene was grown on copper films by a chemical vapor deposition (CVD) method. In this procedure, the furnace was heated to 1050 °C in a 14 cm min2.2/Si substrate; subsequently, PMMA was totally removed by boiling acetone. A graphene sheet (40 × 2200 μm) was fabricated by the combination of photolithography and selective oxygen reactive ion etching (RIE) . Finally, high-density patterned metallic electrodes (Cr 8 nm/Au 60 nm) were deposited onto the graphene sheet through photolithography and thermal evaporation.After spin coating  of the polymethylmethacrylate (PMMA) supporting polymer , the PMMA–graphene–copper layers were put into a solution of ferric chloride to etch copper substrates. The PMMA–graphene layers were rinsed with abundant ultrapure water and transferred to a 300 nm thick SiO3.d1 = 150 nm and d2 = 40 nm in the dash line; 40 μm width of graphene sheets), the number of graphene nanoconstriction units in one array was calculated to be ∼210  was applied to the device until the current dropped in magnitude to ∼pA.After spin coating  with a PMMA layer , we ran a DesignCAD file with a 5 nm-width dash line between each pair of electrodes to obtain 50 μm-length windows by e-beam lithography. The development of resist was performed in a mixture of ultrapure water/isopropanol (1 : 3) at 5 °C with the aid of ultrasonication. Considering the routine condition (4.2 gas. The I–V characteristics were determined using an Agilent 4155C semiconductor characterization system.The devices were immersed in a pyridine solution containing a mixture of amino-terminated molecules (0.1 mM) and the dehydrating/activating agent 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide hydrochloride (EDCI) (1 mM) under the protection of argon. After reacting for 72 h, the devices were removed from solution, rinsed with acetone and isopropanol, and completely dried with a stream of N−1) was applied to the graphene nanoconstriction arrays, and the corresponding current was determined at 10 Samples per s (Sa per s). I–V) characteristics of the electroburning process. Generally, the current increases along with the voltage up to a critical point at which electroburning is induced and the current rapidly drops to ∼pA with one . For SiO2 substrates, J = ∼108 A cm−2 according to numerous results.3,15,21,22 A classical theoretical model was built to show the relationship between the critical current and voltage of each graphene nanoconstriction unit .To understand this regime, we initially regard graphene as a classical two-dimensional resistor obeying the law of resistance :1which hd2 is in the range of 2r, the units that 2r > d2 are cracked by RIE, leaving the rest units as uncut nanoconstrictions. This inhomogeneity was proved in regular SEM characterization  can be evaluated according to the Ohm's law:U is the applied voltage, n is the unit number, Rele is the resistance of the graphene electrode, and Runit is the resistance of each nanoconstriction unit. It is easy to find that Iunit increases when n decreases; this means a positive feedback: the initial breakdown of several units results in the increase of the resistance of the multiplied nanoconstriction array as well as the corresponding voltage drop, and thus, results in the current increase in each rest units, which further promotes electroburning. This regime explained why electroburning events occurred in bursts after the critical point. It is worth noting that the positive feedback ratio (C) equalsRunit/n » Rele. Experimental results indicated that the ratio between the resistance of the nanoconstriction arrays (nearly Runit/n) and the corresponding resistance of the electrode Rele was from ∼0.6 to ∼12 in Region 1 and from ∼9 to ∼2500 in Region 2 , we deem that this current decay derives from the electroburning process of the surviving one or several units in Device 2, which are gradually narrowed by the oxidation from the edge. However, in Device 1, the feature size of each nanoconstriction is larger. Due to the large range of the hot zone and the limited proportion of edge atoms, electroburning is unlikely to proceed only from the edges. In contrast, oxygen can react with graphene with the aid of phonons or random defects,21,28,29 which may cause a rapid, simultaneous oxidation in the full hot zone (and thus the rapid current drop). Specifically, the inelastic scattering of transport electrons may randomly motivate higher vibration levels, namely phonons, of chemical bonds in graphene. The higher vibration energy makes it more favourable for reaction, which allows initial oxidation inside graphene. Both electroburning regimes have been supported by previous reports.12,28 SEM images of Devices 1 and 2  are located in the bottom of Region 2, where the critical voltage is 2–3 V and the critical current is <1 μA. In this area, the devices were almost open circuit at low bias voltages (<1.5 V), and then, the current sharply increased near the critical voltages . In the transition region, there may be a competitive process between two regimes. There are two reasons to explain the existence of the transition region. First, the quantum size effect is gradual along with the shrinkage of the feature size; this means that the control of the quantum effect is continuous. Second, the specific properties of particular devices are not strictly identical; this may cause a broadening in statistics.2I–V characteristics of a device before oxygen etching , before electroburning , after electroburning  and after molecular immobilization . Especially, the current recovered to some extent after molecular immobilization, which is similar to the behavior of a direct cut device (To demonstrate the capacity of electroburnt graphene nanoelectrodes for the application, we attempted to use these devices to fabricate single-molecule junctions. In particular, amine-terminated molecules can be immobilized to nanogapped graphene electrodes, which are carboxyl functionalized at the edges due to oxidation by RIE through amide bonds (t device ; this inIn conclusion, we developed an efficient route to fabricate nanogapped graphene electrodes in combination with dash-line lithography and electroburning. The electroburning behaviors from different graphene nanoconstriction arrays were systemically investigated, which demonstrated that the regime of electroburning depends on the feature size of nanoconstriction units. This relationship between the feature size of nanoconstriction/nanoelectrode units and the corresponding electroburning behavior is promising to offer new opportunities for future device fabrication with nanogapped electrodes.The authors declare no conflicts of interest.RA-008-C7RA13106B-s001


Public participation in community-organized disaster mitigation activities is important for improving disaster mitigation capacity. With data from 260 questionnaires, this study compared the current status of public participation in model disaster mitigation communities and nonmodel communities in a geological-disaster-prone area. Three community-organized disaster mitigation education activities were compared cross-sectionally. A binary logistic regression was used to analyze the effects of attitude, perceived behavioral control, disaster experience, and other key factors on the public’s choice to participate in community disaster mitigation activities. The analysis results indicated that model communities had higher public participation in two efforts, evacuation drills and self-help skills training, and lower participation in activities that invited them to express their feedback than nonmodel communities. The influence of attitudinal factors on the decision to participate in disaster mitigation activities had a high similarity across community types. The public participation in model disaster mitigation communities is influenced by factors such as subjective norms and participation cognition; the behavior of people in nonmodel communities is influenced by factors such as previous experience with disasters, perceived behavioral control, risk perception, and participation cognition and has a greater potential for disaster mitigation community construction. This study provides practical evidence and theoretical support for strengthening the sustainable development of disaster mitigation community building. The geological environment in Southwest China is complex and susceptible to extreme weather conditions. Coupled with the impact of frequent human engineering activities, geological disasters such as landslides and mudslides have occurred repeatedly, most notably in the Wenchuan earthquake in 2008, which induced landslide disasters in up to 200,000 places . ApproxiIn the study of public participation in disaster prevention and mitigation, Pearce argues that public participation combined with community governance can contribute to achieving sustainable disaster mitigation goals . The botSince 2008, the Chinese government has awarded the title of “National Comprehensive Disaster Reduction Demonstration Community” to communities that meet the requirements of the “Management Measures for the Creation of National Comprehensive Disaster Reduction Demonstration Communities” and pass the audit. China’s comprehensive disaster reduction demonstration communities (hereafter referred to as “model communities”) focus on strengthening the construction of community shelters, stockpiling materials, and enhancing the awareness and capacity of community residents in disaster reduction . Wu et aResearch on the construction of disaster mitigation communities has focused on the evolution of community space, macro-policies, and the qualitative evaluation of disaster mitigation capacity ,17, but In this paper, we used model disaster mitigation communities and nonmodel disaster mitigation communities in Jinchuan County, a geohazard-prone area, to distribute questionnaires and conduct semistructured interviews to investigate the factors influencing public participation in “evacuation drills”, “self-help skills training”, and “opinion expression”. The main objectives of this study are as follows: (1) to investigate the degree of public participation in different disaster mitigation activities in both model and nonmodel disaster mitigation communities, (2) to identify the specific factors influencing decisions to participate publicly in different disaster mitigation activities in different community types and analyze the influence of these factors on public participation, and (3) to provide reasonable countermeasures and suggestions for different communities to improve public enthusiasm for participation and enhance the construction of disaster mitigation communities according to the influencing factors on participation in different disaster mitigation activities.The community-based disaster risk management approach has attracted widespread attention from scholars since 2000, aiming to reduce community vulnerability, formulate disaster mitigation strategies and interventions based on local community characteristics and indigenous knowledge, and improve community resilience and recovery when faced with disaster threats . This apActively implementing disaster risk reduction activities is an important approach in risk education and community preparedness. Witvorapong et al.  found thIn terms of public participation in disaster mitigation activities, most studies have concluded that factors such as risk perception ,35, disaIn the study of individual behavioral decision-making, factors such as individual psychology and social relationships should be considered . The theTo summarize, public participation in diverse community disaster mitigation activities is an important task of disaster risk management at present. Based on previous research, this paper comprehensively selects attitudes, subjective norms, perceived behavior control, risk perception, disaster experience, and participation cognition from the perspectives of psychology, natural environment, and social relations to investigate the influencing factors on public behavior in various disaster mitigation activities. To provide an empirical basis for the targeted improvement of community disaster mitigation plans, a comparative analysis was conducted with public participation in model and nonmodel communities. Jinchuan County is located in the northwestern part of Sichuan Province and the southwestern part of the Aba Tibetan and Qiang Autonomous Prefecture in the transition zone between the Sichuan Basin and the southeastern edge of the Qinghai–Tibet Plateau  How do you conduct disaster risk reduction education activities in your community? (2) How do you think participating in community-organized disaster risk reduction education activities has helped you personally? (3) Do you have any suggestions for mobilizing residents to participate in community-based disaster risk reduction activities? A total of 25 interviewees were recruited for the interviews, including 14 from model communities and 11 from nonmodel communities.The questionnaire consisted of three parts. The first part introduced the purpose and background of the study and the basic demographic characteristics. In the second part, the dependent variables were measured, and the three dependent variables of “evacuation drill”, “self-help skills training”, and “opinion expression” were answered as single-choice questions addressing “whether to participate”. The third section of the questionnaire was the core section, which assessed independent variables such as attitude ,62, subjThe previous methods of questionnaire analysis include linear regression, logistic regression, structural equation modeling, etc. Since the dependent variable is an independent binary variable, this study processed the data using binary logistic regression to examine the relationship between the independent factors and event likelihood . The oddThe logistic regression model takes the following form:The OR can be expressed as follows:i denotes an individual; x denotes the independent variable [The marginal effect can be expressed as follows:variable ,72,73.(1)There were more women than men in the sample size;(2)The age level of the respondents was concentrated in the 46–60 age group;(3)The educational level of respondents in nonmodel communities was significantly lower than that in model communities;(4)In terms of occupation, most respondents in the nonmodel communities were farmers, while respondents in the model communities were mainly farmers and self-employed individuals;(5)The monthly income of respondents in nonmodel communities was generally low, with 65.54% earning less than RMB 1500 per month, while 47.33% of respondents in model communities earn more than RMB 3000 per month.The statistical results of the sample demographic variables are shown in Overall, the range of social groups covered by the respondents in this survey and the sample information were highly representative and conducive to the follow-up study.As shown in p < 0.001, indicating that the collected data were suitable for factor analysis. Principal component analysis and orthogonal rotation were used to extract the common factors with eigenvalues greater than one. The results are shown in The factors with the same characteristics were normalized and simplified through dimensionality reduction processing to preserve the integrity of the information to the maximum extent and provide optimized results for the subsequent analysis . First, t-test was needed to examine the variability in the level of variables between the two types of communities. t-tests for the independent variables between the two communities. The results show that there was a significant difference (Sig < 0.05) in the mean values of each variable between different community types.To investigate the factors influencing public choices to participate in community disaster mitigation activities in different community types, a The mean values of “attitude”, “subjective norms”, and “participation cognition” in the model communities were significantly higher than those in the nonmodel communities. This indicated that the model communities have positive attitudes and higher awareness of participatory disaster mitigation activities and are more likely to be influenced by the community and have a stronger sense of consensus.The mean values of “perceived behavioral control”, “risk perception”, and “disaster experience” are higher in nonmodel communities than in model communities, which indicates that the public in nonmodel communities is more affected by the geological disaster environment, has higher risk perception, and has a higher evaluation of their ability to participate in disaster mitigation activities.Holding other factors constant at the mean level, the evacuation drill activities revealed through the data in The behavioral decisions of residents in both types of communities in the self-help skills training activities were positively influenced by personal attitudes (OR > 1), which indicates that, regardless of the type of community, the public can be 7.4% more likely to participate by maintaining a positive attitude toward this activity compared with a negative attitude. The difference is that model communities are susceptible to the negative influence of two factors, perceived behavioral control and risk perception (OR < 1), which means that if these two factors show an increasing trend, it will lower the likelihood of public participation by 10.4% and 8.0%. Nonmodel communities’ perceived behavioral control and perception of group participation positively influence public participation behavior (OR > 1), indicating that the higher the level of perceived behavioral control and participatory cognition, the more likely it is to increase the level of public participation, with probabilities reaching 12.9% and 8.3%.Attitude has a common positive influence (OR > 1) on opinion expression activities for both types of communities, increasing the likelihood of public participation by 17.3% and 14.2% for model and nonmodel communities. Increased levels of subjective norms and participatory cognition by the public in the model communities could increase their likelihood of participation by 5.2% and 6.6%, respectively. People in nonmodel communities were negatively influenced by subjective norms and disaster experiences, which reduced the likelihood of public participation by 7.6% and 6.5%, respectively, but they were positively influenced by perceived behavioral control, which indicated that it could promote public participation by 18.9%.According to the current state of public participation , the modIt is worth noting that the number of residents participating in “opinion expression” in model communities is less than in nonmodel communities. This implies, on the one hand, that model communities are organized and managed more comprehensively and meticulously and have a higher level of resident recognition of participation mechanisms, activity planning, implementation, and the total organization of mitigation activities. On the other hand, nonmodel communities still have shortcomings in the above aspects, and local people have a higher demand for participation and the active expression of feedback out of consideration for their own safety and the development of local disaster mitigation.(1)Factors influencing the “evacuation drill”According to (2)Factors influencing “self-help skills training”According to the findings, the more positive residents are toward self-help skills training activities, the more likely they are to support public participation. Therefore, regardless of the type of community, policymakers must emphasize the necessity of participation in their daily risk communication. Furthermore, this activity was unaffected by “subjective norms” and “disaster experience,” most likely because, as these skills are eminently in the public’s self-interest, the public is more concerned with acquiring self-rescue knowledge to safeguard their own interests.In addition, an interesting result was found: the higher the perceived behavioral control and risk perception of the model community residents were, the less likely they were to participate in rescue skills training by approximately 10.4% and 8.0%, respectively, while other variables remained constant. This marginal effect result reflects the fact that overconfidence may lead to false competence assessment bias and that fear deters people from taking mitigating measures . This alPerceived behavioral control and participation cognition positively influenced public participation in nonmodel communities, demonstrating that the lower the “threshold” of public participation and the more knowledge regarding participation there is, the stronger the public’s incentive to engage. This indicates that there is still room for improvement in disaster mitigation community construction in nonmodel communities and that a large number of resources are still required to invest in and increase public participation in disaster mitigation, which is consistent with the actual situation of most rural disaster mitigation communities in China.(3)Factors influencing the “opinion expression”Consistent with Asare’s report , the facThe difference is that residents of model disaster mitigation communities are positively influenced by subjective norms and participatory cognition in expression activities, whereas residents of nonmodel disaster mitigation communities are negatively influenced by subjective norms and disaster experience and positively influenced by perceived behavioral control. This demonstrates that participation in model communities has a group effect , implyin(1)Increasing the publicity of disaster mitigation and disaster mitigation activities to strengthen the awareness of residents to participate in risk reduction.(2)Reasonable allocation of community resources for disaster mitigation, strengthening the construction of disaster mitigation environments.Based on the analysis of contributing factors, it is clear that community development in geological-disaster-prone locations must use resources wisely and concentrate on strengthening the disaster mitigation environment in nonmodel communities. For example, social resources should be encouraged to provide technical help and financial support, disaster mitigation education events should be arranged on a regular basis, and the “threshold” of participation should be lowered to allow more residents to participate. In daily disaster preparation, the most recent warnings and activities are distributed via WeChat groups, allowing residents to exchange comments. One-on-one, concentrated interventions are set up to help marginalized persons, particularly those who are severely impacted and have a strong subjective will. To minimize the limiting effects of overconfidence and pessimism, model disaster mitigation communities should focus on the observation and direction of the public’s attitude toward risk status and their ability to master rescue skills throughout the deployment of the “self-rescue skills training” plan.(3)Carrying out “one leads many” community exchange activities and allowing model communities to play a leading role.Communication across communities aids in identifying flaws and gaps within the communities themselves. Regular disaster mitigation communication efforts are carried out with the model community as the core and the neighboring rural communities as the targets of information. This provides a model for other communities to learn from in terms of setting up disaster mitigation activities and motivating people to participate. Organization factors as varied as the structure of the disaster mitigation working group, the development of emergency plans, and the design of disaster mitigation publicity, education, and training activities can all be improved by studying the successful experiences of the model communities.Diversified community disaster mitigation activities encourage public participation and strengthen the community’s catastrophe prevention and mitigation and emergency response capacity through a two-way interaction process. However, the implementation of community disaster mitigation methods must take into account the current degree of community and public participation, as well as the elements that impact the public’s choice to participate in various activities. Therefore, this paper takes “evacuation drills”, “self-help skills training”, and “opinion expression” as examples of community-organized activities and compares model disaster mitigation communities with nonmodel communities to determine what specific factors influence the choice of public participation in disaster mitigation activities and the degree of influence under different levels of disaster mitigation infrastructural support.The research results found that: (1) At present, there is a clear difference in the degree of public participation in disaster reduction activities between model disaster reduction communities and nonmodel communities, with model communities relying on resource support to have a stronger advantage in disaster reduction construction, while residents of nonmodel communities show a higher willingness and demand for participation. (2) Attitude is a key factor influencing public participation in disaster reduction activities, indicating that inducing positive public attitudes toward disaster mitigation activities is an important measure to increase the level of public participation across the board. (3) Community disaster reduction planning should reasonably allocate disaster reduction resources and improve the dynamic adjustment of phases. In the process of building future disaster reduction communities, model communities should make phased adjustments to their activity programs based on community characteristics and feedback from public participation and follow up on the public’s skill acquisition and subjective feelings promptly. The motivation of nonmodel communities’ residents to participate is influenced by the pathways to participation and the risk environment; therefore, decision-makers should focus on improving the resource allocation of nonmodel communities and enhancing the demonstration benefits of model communities.There are still some limitations in this paper. First, the sample size only represents the specific situation of public participation in community disaster mitigation in Jinchuan County, a geohazard-prone area. The public community in other areas with different types or levels of risk may have different preferences affecting the results. Second, this paper explores specific factors that influence public participation but does not dig deeper into the interactions and path relationships among the factors; therefore, they can be further specified, extended, and supplemented in the future. The above issues need to be further discussed in future studies.


Additional morphological and crystal structures were examined and confirmed by high-resolution electron microscopy. Subsequently, the investigations of the optical properties evidenced the high optical absorption (98%) and lower band gap (1.75 eV) for the graphene@WS2 compared to the other samples, with good band-edge alignment to water-splitting reaction. In addition, the photoelectrochemical measurements revealed that the graphene@WS2 (1 wt%) exhibits an excellent photocurrent density (95 μA/cm2 at 1.23 V bias) compared with RHE and higher applied bias potential efficiency under standard simulated solar illumination AM1.5G. Precisely, graphene@WS2 (1 wt%) exhibits 3.3 times higher performance compared to pristine WS2 and higher charge transfer ability, as measured by electrical impedance spectroscopy, suggesting its potential use as an efficient photoanode for hydrogen evolution reaction.Tungsten disulfide nanosheets were successfully prepared by one-step chemical vapor deposition using tungsten oxide and thiourea in an inert gas environment. The size of the obtained nanosheets was subsequently reduced down to below 20 nm in width and 150 nm in length using high-energy ball milling, followed by 0.5 and 1 wt% graphene loading. The corresponding vibrational and structural characterizations are consistent with the fabrication of a pure WS Recently, both computational and experimental studies carried out on WS2 have shown its effective role in catalyzing HER with a relatively good yield [2-like materials, such as vertically aligned MoS2, have shown increasingly exposed edges as active sites for HER electrocatalysis, while the basal plane is catalytically inert [2 performances, it is crucial to select an appropriate catalyst-supporting material that can prevent high-surface-area WS2 nanostructures from agglomerating, enhance electron mobility, and overcome the surface overpotential to improve the overall HER performance. Graphene is the other two-dimensional carbon material that would meet the aforementioned criteria. Due to its high ability in electronic excitation and mobility, its mechanical properties, and its high stability, even at the nanoscale, graphene has received rigorous scientific and industrial attention for a long time [2/g), high electron mobility μe at room temperature , outstanding thermal conductivity (5000 W m−1 K−1), and high electrical conductivity (5:6.4 × 106 S/m), as well as a very low weight. These outstanding proprieties enable graphene to be considered an excellent electrocatalyst support for WS2 nanostructures [Hydrogen fuel is considered a promising source of clean energy that could partly replace fossil fuels at the origin of greenhouse gas emissions. Today, there is a growing universal tendency to focus research and development on green hydrogen production by considering the general ecosystem to lower its costs and make it a more affordable clean-energy source, especially through water splitting (WS) ,2,3,4,5.od yield ,14,15,16ly inert . The incly inert ,19,20. Tong time ,24,25,26ructures ,22.2 nanocomposite as electrodes for improved WS reactions. Next, we conducted a systematic structural characterization and assessment of the optical properties to evaluate the performance of the fabricated samples in photocatalysis-driven WS.In this work, we first produced low-cost graphene@WS3) and thiourea (CH4N2S) powders, were acquired from Alfa Aesar™ . Graphene nanoplatelets were purchased from Sigma Aldrich™ St. Louis, MO, USA. The indium tin oxide (ITO) substrates used in this study are from Lumtec™ , exhibiting a resistance < 10 Ω/cm2. All used substrates were cleaned by immersion in detergent, rinsed successively with acetone, ethanol, and deionized water, and dried under nitrogen flow. WS2 nanosheets were prepared using four processing conditions consisting of various WO3 and thiourea contents until achieving the complete suppression of the oxygen residue and obtaining pure WS2 nanosheets. The initial materials’ contents and the corresponding samples are summarized in the The raw materials, namely tungsten oxide  machine with tungsten carbide container and Zirconia oxide balls  were added to the optimized fabricated WS2 nanosheets (S4), followed by high-energy ball milling at 400 rpm for 1 h. To investigate the different physical properties of the resulting compounds, thin films were prepared on top of various substrates, such as glass, quartz, and ITO. 2 nanosheets from aggregating in the transferring tube. Ethanol was used as the host solution.For the graphene@WS2 with or without graphene, which was poured into a 40-megaliter ethanol container followed by water-bath sonication, as shown in For all samples, the spraying procedure consisted of 0.1 g of a mixture made of WSSubsequently, the structural characterization was carried out using a Bruker™ D4 Endeavor X-ray diffractometer with a 1.54 Å CuKα source, and the vibrational analyses were performed with Raman spectroscopy Renishaw™  using a green laser excitation source (532 nm). The microstructure analysis was performed with a Zeiss™  Gemini 500 ultra-high resolution field emission electron microscope (FESEM) operating at low voltage (1 kV), using an In-lens detector. The crystal structure and the morphology of the obtained nanocomposite were investigated by high-resolution transmission electron microscopy (HRTEM) Cs-corrected Titan from Thermo Fisher Scientific™  operating at 300 kV. TEM samples were prepared on holey carbon Cu grids using drop-casting method. The analysis of optical properties was conducted on a UV-vis-near IR spectrometer V-700 JASCO™  and Fourier transform infrared spectroscopy (FTIR) from Thermo Fisher Scientific™ . The electrical impedance spectroscopy (EIS) and the photoelectrochemical (PEC) measurements were performed using PalmSens4™  EIS electrochemical interface.2 samples are shown in 2 phase of cell constants a = b = 3.15 Å, c = 12.32 Å.The XRD diagrams obtained for the four prepared WS3 structure. This indicates that the reaction of the WO3 with the thiourea was not complete; hence, the resulting WS2 of these samples contained WO3 residue. It is worth noting that the strength of the WO3 residue peak was observed to decrease with increasing thiourea content (from sample S1 to S3). By contrast, the WO3 peak was no longer visible at higher thiourea content as it disappeared for the sample S4. This result suggests that the excess thiourea added to the mixture made it possible to obtain the pure WS2 nanosheets.The XRD diagrams of the samples S1, S2, and S3 exhibit an extra peak at (002) position which corresponds to the WO2 samples. All the samples show common WS2 characteristic peaks, i.e., two strong peaks attributed to E2g1 in-plane and A1g out-of-plane vibrational modes appearing at the 350 and 420 cm−1 positions, respectively. The E2g1 mode involves a displacement of W and S atoms, whereas the A1g mode concerns only the S atoms.3 vibration modes at the 293 cm−1, 675 cm−1, and 836 cm−1 positions, respectively, while the S4 only exhibited the vibration modes E12g and A1g for WS2 occurring at 351 cm−1 and 415 cm−1, respectively. As mentioned above, these results confirm that the CVD reaction was fully completed for the S4 and the oxygen was entirely consumed.Similar to the XRD results, the Raman spectra of the S1, S2, and S3 showed the presence of WO2 samples, and the typical Raman spectra are depicted in 2 peaks, graphene vibrational modes were also obtained for both samples at 1560–1575 cm−1 and at 2647–2700 cm−1 for the G-band and 2D-band, respectively. This confirms the presence of the graphene in the processed graphene@WS2 samples.Furthermore, the Raman spectroscopy was carried out on graphene@WS2 nanocomposite samples, FTIR absorption spectroscopy was conducted on pure WS2, WS2: 0.5 wt% Gr, and WS2: 1 wt% Gr, respectively, as shown in To further screen the presence of the graphene in the processed graphene@WS2 nanocomposites and the strength of this peak is more pronounced for the sample with the higher graphene content.As can be seen, the typical graphene absorption peak is present in the graphene@WS2, WS2: 0.5 wt% Gr, and WS2: 1 wt% Gr, respectively. Both the WS2 nanosheets and the graphene platelets are visible. These samples were further investigated by HRTEM and used for the photoelectrochemical measurements.A general view of the sprayed samples on the ITO substrate is given in 2: 1 wt% Gr. The WS2 nanosheets (dark contrast) appeared to be encapsulated in the graphene nanoplatelets (light contrast), as shown in 2 nanosheets. The quality of the nanocomposite was further verified using HRTEM.2 nanosheets and the graphene nanoplatelets, delimited by the blue box highlighted in 2 materials, as demonstrated by the interplanar distances d(002) = 0.62 nm and d(100) = 0.27 nm, illustrated in the red box in 2 and graphene regions given in 2, as demonstrated by the corresponding fast Fourier transform (FFT) intensity image depicted in The investigation of the optical properties was carried out using an optical spectrometer in the 350–800 nm range. 3 impurities induces a decrease in the optical absorption in the visible region. By contrast, the optimized sample S4 showed a relatively unchanged optical absorption. In particular, it remained stable until it reached the excitons position (around 620 nm), at which point it slightly increased. It is clear that the optimized WS2 sample S4 exhibited high broadband light absorption in the visible region, reaching more than 98% compared to the other samples. Using the Tauc formula (αhυ)n = A(hϑ − Eg), the band-gap energy was obtained, as depicted in As can be seen, samples S1, S2, and S3 exhibited similar optical behavior, consisting of a steady decrease in the optical absorption, which started at 93–97% and hit 80% for S1. This suggests that the presence of WOThe obtained band-gap energies were 1.91 eV, 1.87 eV, 1.82 eV, and 1.8 eV for S1, S2, S3, and S4, respectively. The S4 showed the lowest energy, which was in agreement with the broadband optical absorption performances achieved.2 nanosheets, the optical absorption was also measured for both graphene@WS2 samples, namely 0.5 wt% Gr and 1 wt% Gr, and the results are shown in To evaluate the effect of the graphene’s incorporation on the WS2: 0.5 wt% Gr does not seem to enhance the optical absorption . Then, a linear sweep voltammetry (LSV) and chronoamperometry experiments were carried under standard solar simulator (energy~AM1.5G).In this section, the photocatalytic performances of neat WSE0 ≈ 0.197 V at 25 °C and EAg/AgCl is the applied potential.To extract the potential of RHE, the following Nernst equation was used:2 and the distance between the three electrodes was kept at 5 mm. A Pt fishnet (0.5 cm outer diameter) was used as counter electrode, while standard Ag/AgCl was used as the reference electrode. The LSV scan rate was set to 0.1 V/s along 0–1.5 V range. Prior to LSV experiments, all measurements were stabilized for 200 s under zero applied potential. The results are depicted in For both samples, the active surface is about 1 cm2, which was observed to quickly increase with increasing RHE with respect to the applied potential. Note that the highest current density obtained for the S4 WS2 at high applied voltage was reached by the graphene@WS2 sample at very low applied voltage. Hence, the addition of graphene dramatically enhanced the generated density current, six-folds, which was beneficial to HER. To produce WS reactions, a theoretical potential value of 1.23 V versus RHE is required without considering the surface overpotential and the voltage loss due to electron transport. As can be seen, the S4 WS2 nanosheets showed the lowest photocurrent density, of 17 μA/cm2, at 1.23 V versus RHE over the entire potential range. When the graphene was added, the photocurrent density increased vigorously to 95 μA/cm2. The onset potentials of the S4 WS2 and WS2: 1 wt% Gr nanosheets were 0.61 and 0.52 V, respectively. The cathodic shift in the onset potentials indicated an enhanced charge transport; hence, a higher separation efficiency was obtained, even at low ranges of applied potential.As can be seen in J is the current density, Vbias is the bias potential, and Plight is the light power.Moreover, the applied bias potential efficiency (ABPE) was evaluated using the following equation:2/ITO photoanode exhibited an ABPE of 0.79% at around 0.75 V versus RHE, while the WS2: 1 wt% Gr/ITO photoanode reached 4.11% at the same voltage versus RHE. This increase in ABPE in the graphhene@WS2 sample represented a fourfold-higher performance than that of the pristine WS2 nanosheets. This underlines the beneficial effect of WS2 loaded with graphene on photocatalytic WS reactions.The ABPE equation translates how much the cell device using the processed samples as photoanodes is able to produce ionization current under an external applied voltage at constant solar irradiation. Here, the light power was AM1.5G. The applied potentials were converted into the corresponding potential versus RHE using the Nernst equation. The ABPE findings given in 2: 1 wt% Gr/ITO over time, the transient photocurrent was recorded at 0 V of bias with the light on/off cycles at AM1.5G/cm2, using a monitored mechanical shutter. The results depicted in 2: 1 wt% Gr photoanode was examined at a bias potential of 0 V under AM1.5G illumination. A fast decay occurred for the first 100 s. Subsequently, a plateau was recorded, indicating that the photocurrent had reached a value of 0.4 nA/cm2 over the following 100 s. During this time, the photogenerated electrons were transferred to the Pt counter electrode to boost the HER. Consequently, the generated holes could actively participate in the oxidation process at the photoanode site. In our case, the initiation of the WS experiment induced the accumulation of the photogenerated holes at the photoanode site, since no bias potential was applied. These holes could barely be scavenged by water molecules, and recombination occurred, resulting in a decrease in the photocurrent with time. After about 100 s, the rate of generation and consumption of the holes became constant and the photocurrent is stable [2 NSs and WS2: 1 wt% Gr by evaluating the incident photon-to-current efficiency (IPCE), which gives a good estimation of the number of produced electrons with respect of the number of incident photons. The IPCE was determined by the following expression: IPCE (%) = J × V/incident Power. The obtained IPCE was plotted against the applied potential (V vs. RHE) and depicted in To examine the photoresponse of the photoanode WSs stable . Further2: 1 wt% Gr. Therefore, the incorporation of the graphene dramatically enhanced the IPCE, which exhibited an exponential function profile. This indicates that the graphene provided additional electrons circulating in the photochemical cell, which is further proof of the beneficial effect of graphene in enhancing photochemical reactions.2: 1 wt% Gr photoanode, an EIS experiment was carried out to evaluate its charge transfer capabilities. The EIS was conducted on a three-electrode cell and deionized water electrolyte. A Pt fishnet and Ag/AgCl were utilized as the counter and reference electrodes, respectively. The applied voltage was set to 1 V, with a frequency sweep in the range of 0.01 Hz–100 KHz under visible light irradiation at 100 mW/cm2 of power density. The exposed surface area of all the samples was set to 1 cm2. Nyquist plots of the optimized WS2 and WS2:1 wt% Gr and the corresponding equivalent electrical circuit are shown in To further examine the performance of the WS2 nanosheets (45.8 KΩ) compared to the very low resistance obtained for WS2: 1 wt% Gr (10 KΩ). This result clearly shows that the WS2 loaded with graphene promoted a fourfold better charge transfer compared to the neat WS2 sample. This performance undoubtedly suggests that graphene@WS2 is more suitable for use as a photoanode for HER.The comparison of the EIS measurements with the equivalent electrical circuit indicated the higher resistance of the S4 WS2 NSs and graphene. Our findings demonstrate that processing composite materials based on TMD materials combined with a semimetal achieves four-to-five-times better current density at 1.23 V (V vs. RHE), which is necessary to drive WS reactions and hydrogen-evolution reactions. This contrasts with the findings of a previous study [2/rGO and −0.4 V for neat WS2). These values remain low compared to the theoretical potential of 1.23 V required to achieve WS and HER.In summary, in contrast to previously reported work ,27, the 2 were produced in order to be used as highly efficient photoanodes for hydrogen production via a water-splitting reaction. The successful fabrication of the optimized WS2 nanosheets as well as the graphene@WS2 with two graphene contents was confirmed by several combined techniques, including XRD, Raman and FTIR spectroscopies, SEM, and HRTEM. Our main findings indicate that the sample WS2 with 1 wt% graphene exhibited a broadband visible light absorption reaching 98% and an appropriate band gap of 1.75 eV for water-splitting reactions. These outstanding optical properties led to an enhancement of the photogenerated electrons and to a higher charge transfer, as recorded by the photochemical and electron impedance spectroscopy measurements at ambient conditions. Furthermore, associating graphene with WS2 at only 1 wt% content led to an increase in the current density from 17 to 95 μA/cm2 at 1.23 V versus RHE under AM1.5G illumination with ABPE, which was fourfold higher than the pristine WS2 nanosheets. Hence, the graphene@WS2 could be considered a desirable high-efficient photoanode for hydrogen-evolution reactions.Nanocomposite materials consisting of graphene and WS


In terahertz (THz) wireless systems, graphene shows a tremendous promise for the implementation of miniaturized and reconfigurable antennas due to its unique tunable property. This paper presents a wideband beam reconfigurable directional antenna for THz wireless communication systems. The antenna design concept is based on the Yagi-Uda antenna working principle. The proposed antenna consists of a centre-fed graphene-based driven dipole and three graphene-based parasitic elements on either side of the driven element. These graphene-based parasitic elements either act as directors or reflectors by controlling the surface conductivity of these elements. The surface conductivity of the elements is adjusted individually by applying a bias voltage via the chemical potential of the graphene. The main beam direction of the antenna can be reconfigured by controlling the chemical potentials of the graphene-based parasitic elements. Specifically, the proposed graphene THz antenna reconfigures the main beam into four orthogonal directions  at an operational frequency 1.25 THz. The antenna achieves a directional symmetrical radiation pattern with 14 dBi gain and a front-to-back ratio of 15.5 dB. Furthermore, the proposed graphene THz antenna provides a stable reflection coefficient in four reconfigurable cases and an ultra-wideband of 10-dB impedance bandwidth of 120%. Therefore, this novel design technique of graphene-based ultra-wideband high gain beam reconfigurable THz antenna is promising for THz wireless systems. The THz wireless communications have the advantage of more bandwidth, more directionality, and higher data rate compared to the radio frequency and microwave bands. However, the THz band has a high propagation loss, including molecular absorption loss2. Given the high propagation losses in THz wireless communications, the design of a THz antenna plays an important role since THz antennas of high directionality at both transmitter and receiver can compensate for propagation loss. Recently, several antenna designs at THz frequency have been reported in the literature15. However, conventional metal is no longer suitable due to a decrease in conductivity and skin depth in the THz band16. On the other hand, the nanomaterial graphene is a promising candidate for the implementation of THz miniaturized antennas due to the propagation of surface plasmon polaritons (SPP) waves in the THz regime16. Specifically, graphene has gained momentum for reconfigurable THz antennas due to its inherent tunable high conductivity3 . Recently, reconfigurable antennas based on graphene material at THz band have been widely explored17.The use of the terahertz (THz) band, i.e., frequency ranging from 0.1 to 10 THz, has a great interest in wireless communications due to large bandwidth and high data rates20. In the classical Yagi-Uda antennas, the reconfiguration is achieved by employing the switches on the parasitic elements. However, this conventional switch mechanism is not suitable in the THz band. The insertion of switches in THz implementation can increase the complexity of the antenna structure. By exploiting the tunable dynamic conductivity of graphene at THz, few radiation pattern reconfigurable antennas have been designed23. These antennas have dynamic radiation patterns that can be reconfigured, but the adjustable range for the radiation beam is limited.Yagi-Uda antenna is a well-known antenna design for the implementation of pattern reconfigurable antennas24. However, the design process of a graphene-based Yagi-Uda THz antenna is more complicated. In21, the antenna only reconfigures the radiation beam from 24, the authors designed a complicated structure for a reconfigurable four-beam antenna using the Yagi-Uda antenna concept with metal as radiator and graphene as switches for reconfiguration. A design for a switched beam graphene THz antenna using Yagi-Uda concept has been provided in25. In this work, each parasitic element consists of three different graphene strips and are separated by a small distance of 500 nm, which increases the complexity in the antenna structure. The conductivity of graphene strips of each parasitic element adjusted to make the overall length of the parasitic element larger/smaller than the length of the excited dipole, and hence act as a reflector/director of the antenna structure. The bandwidth information of these beam reconfigurable antennas is not available in most of the literature. However, the 10-dB impedance bandwidth of the four-beam reconfigurable antenna in24 and25 are 10% and 42%, respectively. In26, multi-beam reconfigurable antenna based on graphene at 1.243 THz achieved 10-dB impedance bandwidth of 10.5%, and the gain of 6.5 dB with a 12.1 dB front to-back ratio. A beam-scanning seven-element quasi-Yagi-Uda antenna based on hybrid metal-graphene materials is deflected from 27. An array of graphene-based Yagi-Uda antennas is reported in28, which consists of four identical Yagi-Uda antennas, reconfigures the radiation beam from The Yagi-Uda antenna concept has been used to design graphene-based reconfigurable pattern THz antennasWe propose a simple structured wideband beam reconfigurable THz antenna using novel graphene nanomaterial. The antenna design concept is based on the Yagi-Uda antenna principle. The antenna consists of graphene-based driven dipole and parasitic elements.We design a graphene-based Yagi-Uda reconfigurable antenna by using the electromagnetic (EM) simulator CST Studio Suite and provide the simulation technique for the EM modelling of graphene elements and the beam reconfiguration for the proposed antenna structure.We investigate the performance of the proposed antenna by controlling the chemical potential of the graphene-based driven and parasitic elements. The antenna’s radiation direction is reconfigurable, covering a Furthermore, the experimental feasibility and the required bias voltage to enable the beam reconfiguration of the proposed antenna is discussed.In comparison to previous works, in this report, we present a novel and simple way to design a graphene Yagi-Uda antenna with wideband and beam reconfiguration capability in the THz band. In this work, each parasitic element is a single graphene strip of dynamic conductivity, which makes its implementation simpler than previous works. Moreover, the proposed antenna provides wide bandwidth of 120% and high directivity of 14 dBi compared to previous works. The antenna is capable of reconfiguring its radiation pattern, covering a 29j is the imaginary unit, e is the electronic charge, T is the temperature, To evaluate the proposed graphene-based THz antenna structure, it is essential to model the conductivity of graphene at THz frequencies. According to Kubo formalism, the surface conductivity of graphene in the THz band can be approximated asE can be approximated as30.The conductivity of graphene is strongly dependent on the chemical potential 31t is the thickness of the substrate, and Moreover, the chemical potential parameter of graphene can be adjusted by applying a bias voltage to the graphene layer, which can be approximated asThe bias voltage ted from  as4\docu32. For instance, in the present case, the chemical potential E = 9.05 kV/cm. With the increase in the applied bias voltage, more charge is induced on the graphene element, which in turn increases the chemical potential. The tunable chemical potential of graphene enables the different states and reconfigurations in the graphene-based THz antennas. In the present work, the tunable conductivity of graphene via chemical potential is used to reconfigure the main beam into different directions.In the design of the proposed antenna, the chemical potential A graphene-based Yagi-Uda reconfigurable antenna with four orthogonal beams at THz band is investigated. The design of the proposed antennas is based on the principles of the Yagi-Uda antenna. The three-dimensional (3D) view, cross-sectional view, and top view of the proposed graphene-based Yagi-Uda antenna are shown in Fig. mentclass2pt{minimIn the proposed graphene-based Yagi-Uda THz antenna, the graphene-based parasitic elements either act as directors or reflectors by controlling the surface conductivity of these elements. The surface conductivity of the elements is adjusted individually by applying a bias voltage via the chemical potential of the graphene. The chemical potential of the graphene strip determines its conductivity and hence its active charge concentration region or electrical length. The reflectors are the graphene parasitic elements with higher chemical potential of graphene strip, which means a larger electrical length. The directors are the graphene parasitic elements with smaller chemical potential, which means a smaller electrical length. The dependency of graphene conductivity on the chemical potential parameter enables the reconfiguration in the graphene THz antenna. In the present work, the chemical potential entclass1pt{minimaD1, the element 1 is the driven dipole, elements 2, 3, and 4 are directors and the element 5 is the reflector. Similarly, the element 8 acts as the driven, the element 12 as the reflector and elements 9, 10, and 11 as the directors for mode D2; the element 1 as the driven, the element 2 as the reflector and elements 5, 6, and 7 as the directors for mode D3; the element 8 as the driven, the element 9 as reflector and elements 12, 13, and 14 as the directors for mode D4. The four modes with the chemical potential values of graphene antenna elements are listed in Table The proposed THz antenna consists of two graphene-based driven dipole elements (1 and 8) at the middle and 12 graphene-based parasitic elements on either side of the driven element. In addition, 2, 3, and 4 are three parasitic elements on top; 5, 6, and 7 are three parasitic elements on bottom; 9, 10, and 11 are three parasitic elements on left side; 12, 13, and 14 are three parasitic elements on right side. Feeding has been provided at the centre of driven elements 1 and 8. Two driven dipole elements 1 and 8 are placed in crossed manner at the middle, whereas as three parasitic elements are placed with equidistant in top, bottom, left and right side . The proposed graphene THz antenna operates in four different modes and provides four orthogonal beams. For each working mode, one driven element, one reflector and three directors are required. In mode The graphene properties and the dimensions are chosen for the antenna to operate at 1.25 THz frequency. The The normalized radiation patterns of the antenna in four working mode is shown in Fig. 33. As a result, in order to achieve high data transfer rates, THz systems require devices with multiple antennas and beamforming capabilities. The proposed multibeam antennas are expected to meet this requirement. In traditional low-frequency smart antennas, complex signal processing is required to make a decision for the switched-beam antenna as to which beam to access at any time. In contrast, in the proposed THz antennas, the complexity is reduced significantly because only a voltage change is needed for steering the beam direction. The proposed THz antennas can act as promising candidate for THz communication systems due to its orthogonal beam patterns.The major concern in THz communications is the significant path loss effects on account of molecular absorption35. This kind of environments are enabled by reconfigurable intelligent surfaces, a novel class of planar materials that combine the physics of meta-materials with the connectivity and deployment requirements of the Internet of Things. The unique plasmonic and electronic properties of graphene enable efficient reconfigurable intelligent surface at THz37. The user-side multibeam THz antennas and the environment-side intelligent surfaces can build a promising THz wireless system.Recently, intelligent wireless environments have been proposed as promising smart environments that can make capable of sensing and manipulating wavefronts emitted by user devicesA graphene-based wideband beam reconfigurable directional antenna for THz wireless communication system is proposed in this work. The concept is based on the working principle of the traditional Yagi-Uda antenna. The graphene-based parasitic elements either act as directors or reflectors by controlling the surface conductivity of these elements. The surface conductivity of the elements is adjusted individually by applying a bias voltage via the chemical potential of the graphene. The tunable conductivity behaviour of graphene is used to create orthogonal beams. The performance of the proposed antenna is controlled by the chemical potential of the graphene-based driven and parasitic elements. The antenna is reconfigured in its radiation direction, covering a 36038. In the EM simulator, the graphene element is modelled as a thin resistive sheet with surface impedance T. The thickness of graphene strip 39. In the present work, room temperature T = 300 K, Fermi velocity 40. The relaxation time of graphene is computed as 3. The discrete face port (fed by a 50 ohm source) is considered for the excitation of the antenna structure in the CST Studio Suite EM simulator. For mode The CST Studio Suite EM simulator is used to model the graphene and validate the proposed designed antennaE = 9.05 kV/cm. With the increase in the applied bias voltage, more charge is induced on the graphene strip, which in turn increases the chemical potential. The bias voltage of 1.8, 2.7, and 3.6 V are required to enable the beam reconfiguration of the proposed antenna structure.In the EM simulator, the changing of chemical potential parameter enables the reconfiguration in the graphene THz antenna. To achieve the different modes in the proposed graphene THz antenna, the chemical potential of graphene elements varies from 0.4 eV to 0.8 eV. The variation of chemical potential is achieved by applying different bias voltages to graphene strips. In the present case, the chemical potential 41. On top of the polysilicon layer, a silicon dioxide layer of thickness 2 µm can be spin-coated and then, it should be heated at 300 °C for one hour. The chemical vapour deposition grown graphene strips can then be transferred onto the silicon dioxide layer. Graphene conductive ink is also promising for printed electronics. The antenna can also be fabricated using graphene ink on the silicon dioxide substrate.The feasibility of the fabrication of the proposed antenna structure can be explained with the help of Fig. 43. The different bias voltages enable the different chemical potential on graphene, leads to control of surface conductivity in graphene sheets. The tunable conductivity nature of the graphene elements in the proposed antenna enables beam reconfigurability. The modulation of graphene conductivity experimentally can also be achieved by a photoexcitation process41.The reconfigurable capabilities of the proposed graphene THz antenna structure can be demonstrated experimentally by independent control of each graphene strip through different biasing gates