The sensitivity of the modeled thermal conductivity to the geometrical and material parameters of filling particles and the host polymer matrix, filler’s mass concentration, self-assembling degree, and Kapitza thermal boundary resistances at emerging interfaces was numerically evaluated. A fair agreement of the calculated and measured room-temperature thermal conductivity was obtained.The thermal conductivity of epoxy nanocomposites filled with self-assembled hybrid nanoparticles composed of multilayered graphene nanoplatelets and anatase nanoparticles was described using an analytical model based on the effective medium approximation with a reasonable amount of input data. The proposed effective thickness approach allowed for the simplification of the thermal conductivity simulations in hybrid graphene@anatase TiO Polymer nanocomposites based on graphene and its derivatives remain the focus of numerous theoretical and experimental multidisciplinary types of research, which describe some novel structural ,2,3,4, mSuch attention to the nanocomposites is fed by their promise as high-efficiency materials in a very wide range of applications. These include, for example, thermal interface materials ,16,17, aThe state-of-the-art investigation of polymer nanocomposites has advanced over the past decade and generated several comprehensive review articles ,39,40,412O, MnO, NiO, ZnO, CuO, SnO2, CeO2, RuO2, TiO2, MoO2, MnO2, Fe2O3, Fe3O4, Mn3O4, Co3O4, V2O5, and MoO3) and complex oxides 3, and Li4Ti5O12).Recently, polymeric nanocomposites based on graphene/metal oxide hybrid nanostructures have been studied intensively as promising materials for the various above-mentioned applications ,47,48,492), namely rutile and anatase. Today, graphene@TiO2- and graphene oxide@TiO2-based polymer nanocomposites are promising materials that are not only used in energy storage applications but also in photocatalysis [2 and graphene oxide@TiO2 hybrid nanoparticles because titanium dioxide nanoparticles demonstrate nontoxicity and good compatibility with organic solvents and polymers, and they also display good hydrophilicity and mechanical and thermal stabilities [2 [Among the other oxides employed in hybrid graphene/metal oxide and graphene oxide/metal oxide fillers, a unique place pertains to two well-known allotropies of titanium dioxide  Graphene nanoplatelets play the roles of 2D supports to uniformly anchor or disperse metal oxides with well-defined sizes, shapes, and crystallinity;(2) Graphene nanoplatelets act as 2D conductive templates to build a 3D conductive porous network to improve the poor electrical properties and charge transfer pathways of pure oxides;(3) Graphene nanoplatelets suppress the volume change and agglomeration of metal oxide nanoparticles;(4) Metal oxide nanoparticles suppress the re-stacking of individual graphene nanoplatelets;(5) Metal oxide nanoparticles can promote both charge and phonon out-of-plane transfer in multilayered graphene (MLG) nanoplatelets by binding dangling edge carbon bonds of neighboring monoatomic layers with the active sites located on the metal oxide nanoparticles.2 nanocomposites includes in situ growth and covalent and non-covalent grafting [Typically, the synthesis of MLG-TiOgrafting . One shoThe thermal conductivity of the composites is restricted by the high thermal interfacial resistance originating from strong interfacial phonon scattering. To obtain a thermal interface material with nanocomposites containing high thermal conductivity fillers, their concentration would thus be rather high. However, as the material is expected to be electrically insulating to prevent the malfunction of electronic devices at high working voltages, this requires low filler concentrations. Most frequently, reasonable thermal conductivities in the nanocomposites will inevitably result in enhanced electrical conductivities due to a low percolation threshold. Meanwhile, an increased thermal conductivity with filler loading and simultaneously decreased electrical conductivity were reported to arise from the attachment of functionalized molecules or nanoparticles to the filler surface ,59.Assuming that the temperature field obeys a diffusive equation, the kinetic theory predicts the Fourier law to be approach  became oIt is, however, generally agreed that heat conduction in carbon materials is usually dominated by phonons, even in graphite, which has metal-like properties . This isaterials .In the relaxation time  is depicted in As an example, the computed In disordered materials, the glass-like perature . Such κTThe physical mechanisms that may be responsible for such behavior have been extensively debated. The entities ,68. The al model ,70.2 nanoparticles increases the thermal conductivity .It has been widely observed that the introduction of the Kapitza thermal boundary resistance between the MLG nanoplatelets and a host polymer matrix into the model can provide readable accounts of the thermal conductivity experiments and theoretical approaches. In hindsight, the heat transfer enhancement in nanocomposites is largely determined by the thermal boundary resistance, but the conventional heat conduction models for the interfaces fail to have the correct value of the thermal boundary resistance.We begin with the development of our model by introducing the Kapitza resistance  RK betwecle size . For simticle is (2)κf,efthe bulk . The exiface and (3)RK= ∆2 nanoparticles using the two bounding surfaces denoted by the subscripts 1 (MLG) and 2 (TiO2) so that2 and TiO2-epoxy interfaces, respectively. The effective thermal conductivity of the hybrid nanoparticle –(5) to account for the geometrical shape of the filling particles. Therefore, to account for the interphase layers surrounding the fillers of different shapes, the thermal conductivity of the interphase regions (ce RK as (6)κint=2 and of the graphene-wrapped anatase architectures. In the evaluation of Using Equation (6), the above fied see . A graphWe fitted the measured For the epoxy resins, a linear temperature dependence to 300 K ,82. In o2 composite does not affect the 2 content exhibits the saturation of Forming the epoxy/MLG@TiO2 single crystals show that −1 K−1, and then it shows a gradual decrease [These tendencies may be compared with theoretical and experimental results from the literature. In particular, single-layer graphene nanoribbons follow the on modes ,84. Grap[κT∝T2.5 . The the00–500 K  with thedecrease .2 may have an impact on the saturation observed in the curve with the squares in 2 composite samples in the whole studied temperature range cannot be explained quantitatively by the temperature behavior of its constituents, the contributions of the filler–polymer interphase regions should then be taken into account. A substantial difference between the open and closed circle data in 2 fillers.It can therefore be assumed from the above analysis that the behavior of 2 into Equation (2), the temperature dependence of the Kapitza resistance More specifically, to calculate the temperature dependences of effT see  and to eThere are two widely used models for evaluating el (AMM) ,89 and tel (AMM) ,88,89. Bve 200 K . A decreWe may thus assume that a similar temperature behavior of A great number of theoretical models for evaluating the thermal conductivity of composite materials have been developed . To cons2 nanoparticles (phase 2), and self-assembled hybrid MLG@TiO2 nanoparticles (phase 3);(1) The polymer matrix contains three solid phases, i.e., MLGs (phase 1), anatase TiO(2) Every particle embedded into the matrix is surrounded by an interphase layer, which has a molecular structure that is determined by the particle–matrix interaction and differs from the polymer structure beyond the layer;(3) All phases are dispersed randomly and uniformly within the matrix.2 hybrid nanosheets proposed earlier in ref. [We start from the model developed by Su et al. , where t in ref. . DiffereIn our case of a three-phase composite material, the basic equation of the model (see Equation (4) in ref. ) takes tThe parameters The explicit expressions for the functions By using the model in the “soft-spheres” approximation, first of all, we complete a fitting procedure to match the calculated values of −1·K−1. The resulting magnitude of −7 to 0.62 × 10−7 m2∙K−1∙W−1) seems to be appropriate. We can, for example, compare this value with the calculated room-temperature thermal boundary resistance of the Cu/Si interface, which is 5 × 10−4 m2∙K−1∙W−1 [As expected from ∙K−1∙W−1 .−8 m2∙K−1∙W−1 was obtained. The effective cross-plane thermal conductivity of ≈3.3 W m−1 K−1 was reported, whereas the in-plane thermal conductivity varied between ≈650 and 1000 W m−1 K−1.Experimentally, it is rather difficult to distinguish between the thermal resistance of a thin layer and the thermal resistance of the substrate. Zheng et al.  treated Multilayered graphene nanoplatelets typically contain structural defects, including point and edge defects, surface wrinkles, mesovoids, etc. The effects of defects on the interface’s thermal conductivity in graphene/epoxy composites were observed by employing molecular dynamics simulations . Among tThe variation in the interfacial thermal resistance with respect to the functionalization, isotope, and acetylenic linkages in graphene is also systematically examined using molecular dynamics . The graStrictly speaking, the thermal boundary resistance for the in-plane graphene–epoxy interface (r1Z) see . These s3 nm (average linear dimensions of our nanoplatelets) yields 2 composite due to the thermal screening of graphene nanoplatelets by titanium dioxide fillers. Therefore, exploiting the case Inputting ·r1Z see . Thus, aWe note that the properties of composites appear to depend not only on the size but also on the aspect ratio of the fillers One can therefore consider the dependence of The results in It should be borne in mind that, to make numerical estimates of the impacts of the interphase layers on the structural characteristics of a three-phase polymer nanocomposite using the relations given in We therefore suppose that the assumption of the constant values of 6H18N4), the For simplicity, we postulate that the layer’s shape is similar to that of the nanoparticle itself, and the layer’s spatial structure is homogeneous along the surface of the nanoparticle and varies only along the surface’s normal direction. With such an assumption, i1,2 see . The molr matrix ,96. This10–14 nm . The radAs for the values of ngstroms . On the roms [ρ0 . TherefoFor example, if it is assumed that −5 for the case of It can be concluded from these calculations that the chosen sizes of the filler’s loading allow one to avoid the interphase layer overlap and percolation effects. This will be discussed further below.−3, we find a minimal value of The overlapping effect can be avoided at low values of mated by (9)LpφPT (2) The particle assembling decreases 2 interphase interaction.(3) It is also interesting to note that −7 m2 K W−1 (curves 3 and 9 in −9 m2 K W−1 (curve 10).−7 m2 K W−1 (curves 3 and 9 in −9 m2 K W−1 (curve 10). Remarkably, a sensitivity of A general expression for the effective thermal conductivity ained in  in the e κ2,eff, , free grThus, as expected, the effective thermal conductivities of the filling particles increase with the decreasing It should be mentioned that the curves presented in Evidently, the value of the thermal boundary resistance at the filler–polymer interface . For example, the covalent interactions of oxidized graphene’s basal and lateral surfaces with epoxy are dominated by hydroxyl, epoxy, and carboxylic molecular groups . As a reMoreover, an enhanced conjugation between fillers and a host polymer matrix can happen through noncovalent interactions by attaching some specific secondary ligands on the filler’s surface. Various approaches of filler-to-ligand noncovalent binding include electrostatic interaction, π-π stacking, and H-bonding . For MLGThe grafted individual moieties or ligand-moiety chains in a functionalized filler can act as heat transfer channels between the filler and a host polymer matrix, decreasing phonon scattering at this interface and thus reducing the thermal boundary resistance e matrix ,107. In On the other hand, the surface functionalization breaks the regular surface structure of the fillers and reduces the intrinsic mean free path length of the phonons, acting as additional scattering centers for the phonons. Molecular dynamic simulations showed that the in-plane thermal conductivity of infinitely long graphene nanoribbons  for the complete self-assembling  method [To prevent the resulting MLG material from oxidizing, it was kept as the suspension. The particles were about 5 × 5 μm) method  by using2-anatase nanoparticles were deposited on the MLG by adding them into the initial ethanol-based suspension of the MLG before its ultrasonic treatment. The specific surface area of the anatase particles was ~1500 m2/g.The TiO2CH2NH2)2 [The commercially available CHS-EPOXY 520  DGEBA-epoxy resin based on Bisphenol A diglycidyl ether (DGEBA), of epoxy group content (E-Index) 5.21–5.50 mol/kg, with an EEW  of 182–192 g/mol was used as the neat resin. Diethylenetriamine (abbreviated as Dien or DETA) was used as a curing agent. DETA is a nitrogen-containing organic compound with the formula HN(CHCH2NH2)2 . The epoCH2NH2)2 .2 mass loading values , and TEM images of a hybrid graphene@anatase TiO2 nanocomposite are shown in (b) and (c). It is seen in 2 particles are well dispersed over the MLG surfaces. The high-resolution TEM image shown in The morphology features of the nanocomposite were investigated with scanning electron microscopy (SEM) using a JEOL JSM-6490 microscope and with transmission electron microscopy (TEM) using a JEOL JEM-2100 microscope. 2 particles have a diameter of ~30–70 nm, while the thickness of the MLG nanoplatelets ranges from about 30 to 150 nm. One needs to keep in mind that these dimensions are randomly distributed through irregular MLG@TiO2 platelets. So, one needs to choose the values of the MLG and TiO2 thicknesses (both are taken to be 50 nm above), and then obtain the numerical continuation solution branches in It was revealed by the microscopy that the TiOHere, we used the two-probe measurement method to measure thermal conductivity . Our autBy maintaining the stationary heat flux, one can write the following relation to evaluate the thermal conductivity (14)κ=QL3, which made it possible to place them inside the sample without difficulty.The samples were cylindrically shaped with a diameter of 12.5 mm and a height of 6 mm. Two holes with diameters of 1 mm were drilled in the samples from the top and bottom surfaces to the center, in which the temperature sensors were placed  to model the temperature distribution using the COMSOL 5.3a and typical thermal conductivity parameters for diode materials, which are ing mass . The simThe temperature variation across the dashed line at Other factors to be taken into account when assessing the accuracy of the measurements are as follows: Copper wires with a thickness of 50 μm and a length of 100 mm were used to feed the diodes. Their thermal resistance is much higher than the thermal resistance of the sample, allowing for a heat leakage to be quenched. The epoxy resin without hardener was used to give a better thermal contact between the sample, heater, and cooler. A plastic screw defining a point contact constriction with a heat-insulating fastener was used to clamp the sample, which yielded a heat loss of less than 1%. With the above assumptions, the errors in the measured thermal conductivities do not exceed about 5%.The sample was placed in a closed-cycle cryostat  that was used to vary its temperature. The temperature in the cryostat was controlled using a Lake Shore 331S controller through the computer’s RS232 digital port. Measurements were carried out in the temperature range from 40 to 300 K.A theoretical model based on the effective medium approximation was developed to calculate the loading dependence of the thermal conductivity 2 nanoparticles within a temperature range from 40 K to 320 K. When the concentration of anatase in the composites increased, a saturation tendency in the We also measured the temperature dependence of the thermal conductivity of epoxy nanocomposites filled with self-assembled hybrid nanoparticles composed of multilayered graphene nanoplatelets and anatase-TiOThe numerical results clearly illustrate the thermal screening effect of a low-conductive anatase layer that covers high-conductive graphene nanoplatelets. The observed growing thermal conductivity after raising the temperature is not only related to the increasing intrinsic thermal conductivities of both the fillers and host epoxy but is also subject to temperature-induced variations in the thermal boundary resistances.An effective tailoring of


Manual composition of tasks and exams is a challenging and time-consuming task. Especially when exams are taken remotely without the personal monitoring by examiners, most exams can easily lose their integrity with the use of previously done exercises or student communication. This research introduces an approach that incorporates the principles of the generative software development and aspects of the feature-oriented product line engineering process into the field of question creation and generation. The resulting generator can be used to generate single-choice-question-families by means of written question templates. The generated questions within a question-family differ based on the set features and parameters and can be imported into the target learning management system ILIAS. Without much effort, examiners and educators can use the generator to create variants of their questions and deliver them to their students. Constructing exam questions is without saying a very time-consuming and challenging task for all examiners. Especially when teaching, learning and assessment concepts are moving more towards hand-on approaches with many exercises. This in turn drives educators to use automated and rapid feedback mechanisms further facilitated through smaller scaled learning experiences. In such a way, content is clustered to be absorbed through small units of learning and to be made available on demand, so that learning is neither location- nor time-bound.Additionally, through the pandemic years, many changes had to be made and new situations had to be accounted for. The COVID-19 pandemic situation not only forced the teaching to be in digital spaces, but also many exams had to be made available in some remote way. This not only meant that in comparison with in person examinations, students were often able to use all of the lecture materials and notes, but this also opened up the possibility for students to easier communicate with each other.In the specific case of the University of Leipzig, the institution interpreted both German and EU law in such a way that virtually all exams were conducted online. Due to data privacy, no identity check was carried out apart from the login to the exam. Furthermore, it was not allowed that the examinees and their surroundings were monitored. Therefore, examiners had to assume that the students would use aids or solve the exams together. To prevent such actions, many educators started to create multiple versions of the same questions to at least hinder communication. All in all, this requires a lot of time and effort to ensure that the questions possess an equal quality and difficulty. In order to ensure examination fairness, task variations or task specification can be used so that the tasks differ from each other and are designed differently.The prototype presented in this paper focuses on multiple-choice, or more specifically single-choice questions. In the approach presented here, which is part of an ongoing research, different impulses from different fields are combined. At the forefront of this research stands the paradigm of generative software development according to the principles of Czarnecki , whose aProduct line engineering is an approach to software development that emphasizes the reuse of existing assets and knowledge in order to develop and maintain a product line of related software products more efficiently . Aldabe et al. , VimalakDescribed in this paper, the FeatureIDEAs described in the introduction, the methodology is based on the paradigm of generative software development and aims to transfer its essential aspects into the domain of question generation. According to Czarnecki , generatApel et al. , p. 19 sFor this reason, it is important to clarify the main aspects and process steps that are relevant for the adaption. Firstly, a feature is a characteristic or end-user-visible behavior, that is used to specify commonalities and differences for communication between stakeholders, system structure, reuse and for the software life cycle  to replace the parameter itself with a value from its value range.For the specific question generator, the following Fig. Inside the process of domain implementation reusable artefacts are to be developed that correspond to the previously identified features. These artefacts usually contain the design, tests, documentation and source code, but this basic idea can also be applied to non-code-artefacts. Since this step specifically targets the solution space, a general implementation strategy has to be chosen to create a reusable framework . A DSL is a language that is created to solve specific problems in a particular domain Martin, . The impBased on this, each template consists of at least the five sections that were identified as mandatory features in the domain analysis. In addition, there are the eleven optional sections that can be present. Each section is initiated by the identifier @-character like @AUTHOR and is followed by a predefined structure to efficiently read in files as shown in line 3 and 4 or Fig. After the template is parsed, the generator proceeds to first generate all valid combinations of answer possibilities and parameters with respect to the set criteria, exclusions or dependencies. When all combinations are created, the questions are put together for either a specified amount, of semi-randomized questions, or all valid combinations of answer possibilities combined with all valid parameter combinations.c = number of correct answer possibilities, w = number of distractors, p = number of parameter values.For the case that there are no exclusions for answers and no dependencies between parameters the formula for all questions is based on the combination without repetition, multiplied by the number of correct answer possibilities and multiplied by the product of the number of values in the parameter value ranges.As shown in Eq. After the generation of all valid questions, the generator proceeds to create a corresponding output for the import into ILIAS. Since the generator is designed to generate whole question pools, a corresponding folder structure and the necessary XML-files are generated. The whole structure can then be easily packed into a Zip-file and imported into ILIAS as a question pool. The programme sequence described here is illustrated again in Fig. For the development of the generator, a reactive approach was chosen to realize an initial version of the envisioned product line and to progressively further develop the system (Metzger & Pohl, The product derivation or in other cases product—generation, -configuration or -assembly, is the production step of application engineering, where the reusable artefacts are combined with the results of the requirements analysis. This more or less automatable process can involve several other development or customization steps (Apel et al., Overall this step represents the creation of the question-template including the specification of the used parameters. Additionally, a few different steps are checked throughout the generation. This starts with the verification of the parsed template, by using the requirements from the domain and requirements analysis to assess if certain criteria are met, for example, if every parameter has a valid value range. At different stages the validity of the generation gets checked and the question generation is skipped or stopped if it is faulty.As the creation of the question-template is necessary for the creation of question families, Fig. Figure To now express much more variety the question template can be parameterized. As shown in Fig. Of course, the question-template of Fig. As this paper is part of an ongoing research activity, its aim is to introduce a tool and a methodological approach to generate question families based on the principles of software product line engineering, which can be developed further. These principles and corresponding development process were applied to the creation of a single-choice-question-generator. The resulting generator enables educators to design question-templates by the use of a simple and lightweight domain specific language. The templates get generated by either use of multiple manually written answer possibilities, or the use of question and in turn answer parameterization. After the generation process, examiners receive the generated questions as importable files for the use in the learning management system ILIAS.By the use of this system, a few examinations have been conducted in the summer term of 2022. In result, for example a single-choice exam was conducted with 40 questions for each participant, wherein total 538 different generated questions were used for the examinations. By the use of the generator, the examiners were able to create question-families via the question-templates, so the participants received comparably similar questions, according to the judgement of the examiners. In particular, only one question-template had to be created at a time to generate multiple questions, in turn saving time in creation, quality assurance and import into the system. In addition, the generator will further be used in the following terms for self- and online-assessments so that students can check their own knowledge and understanding.The generator can easily be used by educators and examiners outside of the computer science field, with or without changes to the question-templates. In addition, it can be adapted for other online learning platforms to use such an approach to semi-automate task generation, where students are provided with similar tasks to improve their skills in the respective field or with specific task types. This would include for example the combination with different learning taxonomies like the revised Bloom taxonomy (Krathwohl, Finally, such a generator can help educators and examiners when creating questions and students when learning with different iterations of questions. But even though the question-templates in their simple form are easily created, creating complex templates can still be time consuming for complex templates, since the overall question quality depends more on the user and less on the functionality of the generator.Since the questions are not created and parameterized by the generator itself but by the examiner, it is important to highlight that the comparability and difficulty of the answer alternatives is still up to the examiner. Therefore, the actual similarity in difficulty level, could be investigated as the subject of a follow-up study. In addition, by using this kind of question generation for multiple-choice questions the common item analysis methods like Cronbach’s alpha/Tau-equivalent reliability, selectivity and difficulty index are not applicable, since the questions are only similar but otherwise unique with respect to their combination of answer possibilities and parameters. Additionally, most of our exams at the university are conducted with a smaller number of students so that most of the unique questions are only provided to a very small fraction of students, which in turn makes the methods unavailable or very inaccurate. Therefore, it must be explored, which methods can be used to analyze such parameterized tasks, so that in the long term the similarity and difficulty of examinations for different students can be guaranteed. If such methods do not already exist, alternative static quality assurance methods must be developed.For the generator itself, there are many possibilities to extend its functionality, that can currently be seen as shortcomings. First of all, the used DSL is rather rigid in its applicability. Therefore, certain features can and should be extended or reworked, like the ability to parameterize the picture section to include specific images based on the specified parameters. Additionally, analog to the approach of Nagasaka  it is poAlthough most features are independently defined and implemented, which eases the capability to change them, some features like the parameters, their value range and the dependencies/interactions are strongly coupled, whereby adapting them would require a greater effort. This may also apply to certain features to be changed or newly created, as they have been designed for use in our specific cases, whereby other study courses would have different requirements. As the generator is a research prototype, the source code itself might currently not be a good representation of the principles for software development. Therefore, the generator must be further developed or, if necessary, newly developed, considering various aspects of software engineering. For this reason, additional aspects of software product line management should be introduced, to enable the sharing of artifacts for reuse and adaption.Additionally, the generator can be extended to generate output for other learning management systems and to generate further question types, surveys or images. For the future work with template-based question generation, the approach is to be further developed to be used for generating programming exercises and images especially various types of diagrams like flowcharts or UML class diagrams.With the emergence of ChatGPT respectively models of the GPT 03 family and other AI-driven approaches, most online exams can for the most part be nullified. Our approach should be no different, as such a system can provide an answer within seconds and a parameterized task is not a major obstacle, as it would be for a student. Therefore, in the educational domain, research must be done to determine which testing methods can be used to test the skills of students, but which an AI is not capable of. However, it should be noted that the generator is still operational and useful, for example for examinations that are conducted in several rounds, so that students cannot exchange the specific answers. However, through the use of AI-driven approaches like Vimalaksha et al.  and VachFinally, it should be pointed out that the system is currently only designed for the parameterization of single choice tasks, which is mainly useful for knowledge testing. As there are many more aspects throughout the learning process, future research should be concerned with investigating to what extent feature orientation of tasks can be used to ensure a better learning process. For example, feature decomposition of tasks can be used to create an adaptive system to help students overcome learning problems, and parameterization can allow students to test their knowledge in a repeatable and independent way.https://github.com/NWillert/Template-basedGeneratorForSingleChoice.Generator source code available under:


This 3D network hindering the stacking of graphene sheets provided channels for hydrogen diffusion to improve the hydrogen adsorption kinetics. Importantly, the construction of the three-dimensional palladium-phosphide-modified P-doped graphene hydrogen storage material improved the hydrogen absorption kinetics and mass transfer process. Furthermore, while acknowledging the limitations of primitive graphene as a medium in hydrogen storage, this study addressed the need for improved graphene-based materials and highlighted the significance of our research in exploring three-dimensional configurations. The hydrogen absorption rate of the material increased obviously in the first 2 h compared with two-dimensional sheets of Pd3P/P-rGO. Meanwhile, the corresponding 3D Pd3P0.95/P-rGO-500 sample, which was calcinated at 500 °C, achieved the optimal hydrogen storage capacity of 3.79 wt% at 298 K/4 MPa. According to molecular dynamics, the structure was thermodynamically stable, and the calculated adsorption energy of a single H2 molecule was −0.59 eV/H2, which was in the ideal range of hydrogen ad/desorption. These findings pave the way for the development of efficient hydrogen storage systems and advance the progress of hydrogen-based energy technologies.The development of efficient hydrogen storage materials is crucial for advancing hydrogen-based energy systems. In this study, we prepared a highly innovative palladium-phosphide-modified P-doped graphene hydrogen storage material with a three-dimensional configuration (3D Pd As a consequence of population expansion and evolving lifestyles, global requirements are progressively escalating while encountering environmental problems and an alarming resource depletion rate. The damage that fossil fuel usage has caused to the environment has increased the demand for clean, sustainable energy ,2,3. Hydgraphene .However, as a two-dimensional material with a thin sheet structure, graphene sheets tend to stack together spontaneously due to van der Waals forces and π-π bond interactions ,26. Irre3O4 nanosheet hybrid decorated with Pd for hydrogen evolution. They confirmed that the 3D network architecture was favorable for the mass transport of produced hydrogen [Furthermore, adsorption is also a mass transfer process. Increasing the specific surface area of materials can improve the adsorption sites and subsequent capacity. Constructing a three-dimensional graphene network may provide a valid solution to prevent the graphene sheets from aggregating. The unique three-dimensional lamellar folds and pore structure of graphene can effectively prevent this interlayer accumulation, which is the intrinsic reason for the stable existence of 3D graphene . Bi et ahydrogen . Jiang ehydrogen . Thus, shydrogen .3P0.95/P-rGO was obtained by thermal reduction in a H2/Ar atmosphere. Palladium phosphide was grown directly on the three-dimensional graphene substrate. This 3D structure could effectively promote mass transfer. The multi-stage gap structure helped the gas be transported to/separate from the reaction center to promote molecular dynamics. Therefore, the as-prepared 3D Pd3P0.95/P-rGO-500, which was calcinated at 500 °C, achieved a hydrogen storage capacity of 3.79 wt% at 298 K/4 MPa. Meanwhile, the hydrogen absorption rate of the material increased obviously in the first 2 h compared with 2D sheets of Pd3P/P-rGO.Based on our previous work, herein, a 3D Pd/P co-modified graphene hydrogel material was successfully prepared by a hydrothermal method, and 3D Pd3 were first added to a 1000 mL beaker. After that, 100 mL of concentrated sulfuric acid was slowly added to the beaker, and 12 g of KMnO4 was slowly incorporated with continuous high-speed stirring. The as-obtained mixture was thoroughly stirred in an ice water bath for 8 h. Afterward, 3 vol% H2O2 solution was added to the beaker to completely reduce the excess KMnO4 until the brown solution turned yellow. The GO solution after the reaction was kept static at room temperature and was observed to change from bright yellow to brown with obvious stratification. The supernatant was poured out, and the precipitate was washed twice with concentrated hydrochloric acid. Then, deionized water was added repeatedly for cleaning until the pH value of the solution was close to neutral. The GO solution with 3 wt% content was obtained after filling to a constant volume of 1000 mL.The modified Hummers method was used to produce graphene oxide. Briefly, 5 g of graphite powders and 1 g of NaNO2, 120 μL phytic acid, and 33 mL deionized water in a 100 mL beaker using ultrasound for 30 min. Then, the above solution was transferred to a 100 mL Teflon lining. After that, the lining was sealed in a stainless-steel high-pressure reaction kettle for 12 h for the hydrothermal reaction, and the temperature was kept at 160 °C. After the reaction, the cylindrical hydrogel material was freeze-dried and then heated to 900 °C, 700 °C, 500 °C, and 300 °C for 1 h in a 10 vol% H2/Ar atmosphere. The 3D-configuration Pd3P0.95/P-rGO prepared at different thermal reduction temperatures is denoted as 3D Pd3P0.95/P-rGO-Y , where the numbers 300, 500, 700, and 900 represent the reduction temperatures.We mixed 33 mL GO solution, 78 mg Pd(OAc)2 adsorption energy, transition state, and energy barrier, with a focus on characterizing the hydrogen migration through the Pd3P cluster sites to the P-rGO surface. The Vienna Ab initio Simulation Package (VASP) was used to perform the calculations. Ab initio molecular dynamics (AIMD) was utilized to study the model. The exchange and correlation interactions were described using generalized gradient approximation (GGA) in the form of the Perdew–Burke–Ernzerhof (PBE) functional. The calculations used a Brillouin region of 5 × 5 × 1 as the k-point value; the geometry optimization structure was obtained by relaxation until the force on each atom was less than 0.02 eV/Å; and the convergence criterion for energy was set as 1 × 10−4 eV. The cutoff energy was 450 eV, and all calculations considered spin polarization. The study employed an equation to determine the adsorption energy of the H2 molecule, taking into account the vibration effect for a gas phase, only as it is nearly negligible for a solid system.2 adsorption energy, 2 molecule, and A graphene surface model consisting of 60 atoms was utilized in this study, and a vacuum layer of 15 Å was added along the Z-direction to avoid any interactions between neighboring layers. The single graphene model with 59 atoms was obtained by substituting a carbon atom with a phosphorus atom from the graphene sheet and attaching the oxygen atom to the slab, thus creating phosphorus-reduced graphene oxide (P-rGO). The structure was subsequently optimized. The study employed density functional theory (DFT) to calculate the binding energy, H3P0.95/P-rGO, mainly showing a fluffy columnar structure. The SEM images of the as-prepared materials  prepared at different thermal reduction temperatures. With the increase in the thermal reduction temperature, more oxygen-containing groups in the graphene were reduced, thus forming defects similar to vacancies. At the same time, the doping degree of P atoms further increased, leading to an increment in the ID/IG value of the sample  prepared at different thermal reduction temperatures, and the inset shows the particle size distribution. The N2 adsorption–desorption curves of the Pd3P0.95/P-rGO-Y  at 77 K showed the characteristics of a type IV isothermal adsorption line, and an obvious hysteresis phenomenon occurred during the N2 desorption of the four samples, which indicated that the material had a rich pore structure, that is, a large number of mesopores existed. We found that the average pore sizes of the four samples were all distributed around ~3.8 nm, except for Pd3P0.95/P-rGO-300, in which the number of 3.8 nm mesopores was lower, as shown in the inset in 3P0.95/P-rGO-Y . Pd3P0.95/P-rGO-900 had the largest surface area and pore volume at 339.67 m2/g and 0.379 cm3/g, respectively. The specific surface area and pore volume of Pd3P0.95/P-rGO-300 decreased to 50.51 m2/g and 0.130 cm3/g, respectively, when the thermal reduction temperature dropped to 300 °C. With the decrease in the thermal reduction temperature, Pd ions could not be reduced to obtain the expected palladium phosphide, and nor could the oxygen-containing groups be completely reduced.3P0.95/P-rGO-300 were reduced, leading to an obvious reduction in the specific surface area and pore volume. This showed that both the defect degree and the micro-structure in the material were closely related to the thermal reduction temperature. The influence of metal and non-metal doping on the surface area and pore characteristics of particles was investigated by Safia et al. [BET of the catalysts. Furthermore, Sahoo et al. [Combined with the Raman test results in a et al. . In a sea et al.  demonstro et al.  reportedo et al. .3P0.95/P-rGO-Y  samples, as shown in 3/2 and P 2p1/2, respectively, which corresponded to Pd-P bonds, indicating the successful synthesis of Pd3P0.95 particles in the material [5/2 and 3d3/2 orbits of Pd(0), respectively. The peaks located near 336 eV and ~342 eV correspond to the 3d5/2 and 3d3/2 orbitals of Pd(II), indicating that Pd with a high valence state existed due to the formation of a Pd-O bond [To further study the electronic structure and chemical valence of the elements on the surface of the material, X-ray photoelectron spectroscopy (XPS) was performed on the 3D-configuration Pdmaterial . The EDXd-O bond .3P0.95/P-rGO-Y  prepared at different thermal reduction temperatures under the conditions of 4 MPa/298 K and the corresponding hydrogen storage capacity. With the decrease in the thermal reduction temperature, the hydrogen storage capacity of the material increased first and then decreased, reaching the maximum value (3.79 wt%) when the thermal reduction temperature was 500 °C. This was because reducing the thermal reduction temperature could effectively prevent the nanoparticles in the material from agglomerating and subsequently falling off. Thus, the size of the modified nanoparticles in the material was well controlled, and the hydrogen spillover capacity was enhanced, contributing to an obvious increase in the hydrogen storage capacity. However, we found that the Pd could not be fully phosphatized at 300 °C. Therefore, the hydrogen spillover effect of the Pd3P0.95/P-rGO-300 was greatly reduced, and the hydrogen storage performance decreased sharply.3P0.95/P-rGO-900 showed the lowest hydrogen absorption amount of 72.5% in the first 2 h, indicating that the hydrogen absorption rate was directly related to the particle size of the modified particles in the material. The smaller the particle size, the higher the hydrogen absorption rate. The hydrogen absorption rates of the four samples were significantly higher than in our previous work for 2D Pd3P/P-rGO (61.8%) [3P0.95/P-rGO was mainly due to the formation of a 3D structure, which could greatly enrich the pore structure in the material and provide channels for hydrogen diffusion, thus accelerating the hydrogen absorption process. During the spillover process, the hydrogen molecules underwent dissociation on the Pd3P0.95 nanoparticles and subsequently migrated to the surface of the graphene. The dissociated hydrogen species, chemisorbed onto the surface, involved covalent interactions, whereas the absorption of hydrogen molecules onto the graphene was governed by weaker van der Waals forces, which represented non-covalent interactions. Additionally, it is noteworthy that the environmental temperature and pressure exerted a significant influence on the hydrogen storage capacity. Experimental results indicate that reducing the test temperature and increasing the pressure of hydrogen has a favorable effect on hydrogen adsorption [ (61.8%) . The impsorption .3P, P-rGO, and P-doped graphene (P-G) were calculated based on DFT, and the optimized structures are shown in 3P and P-rGO and −2.14 eV between Pd3P and P-G. The results showed that the reduction of the oxygen atoms could increase the binding energy of the cluster and slab. The higher the binding energy, the lower the chance of the agglomeration of transition metal (TM) atoms and vice versa. DFT simulations were performed at 0 K, and the structural integrity of the system had to be checked at room temperature (300 K). In our case, wherein Pd3P was attached to the P-rGO, it was critical that the TM atoms did not dislodge from the P-rGO at higher temperatures. The AIMD simulations considered these concerns. The simulations were carried out at a temperature of 300 K in a canonical ensemble (NVT) for 1 ps with a time step of 1 fs. The MD snapshots of Pd3P/P-rGO are shown in 3P cluster and the change in the C-C bond length were negligible, highlighting the thermal stability of the structure and supporting the material’s practical application in hydrogen storage systems. Because the probability of metal atoms or clusters aggregating on supports is a major downside of transition metals in graphene-based materials, we know that the metal–metal interactions are stronger than chemical interactions between metal atoms and carbon atoms in the support [2 desorption [The binding energies of Pd support . This MDsorption . In our sorption .2 molecule is shown in 2 when the zero-point energy correction was taken into account. A negative adsorption energy value indicates the attraction of H2 molecules to the cluster, implying favorable adsorption. Adsorption mechanisms that fall between physical and chemical adsorption are required for the successful implementation of hydrogen storage in ambient conditions. Previous research has suggested an adsorption energy range of −0.20 to −0.60 eV [2 molecule, the stretching of the H-H bond length was found to be minimal, with a difference of less than 0.3 Å [2 was preserved during adsorption and the association between the H2 molecule and the Pd atom was of the Kubas type.The optimized structure of a single adsorbed H−0.60 eV , which aan 0.3 Å , indicat2 molecules and the migration of H atoms from the site of dissociation to the supporting substrate. In this study, the spillover process of a single hydrogen molecule adsorbed on Pd3P/P-rGO was computed using the nudged elastic band (NEB) and climbing image nudged elastic band (CINEB) [2 adsorbed on Pd3P/P-rGO, spillover occurred at higher temperatures due to the higher energy migration barrier. The DFT results were in line with experimental data showing that Pd3P0.95/P-rGO-300’s hydrogen spillover effect was substantially reduced. The relationship between temperature and spillover reaction time is depicted in 3P0.95/P-rGO-Y  samples were much higher than those of some graphene-based materials previously reported in the literature   methods.ture see  under am3P0.95/P-rGO) using a hydrothermal method followed by calcination. The three-dimensional network structure of the material hindered the stacking of graphene sheets and provided channels for improved hydrogen diffusion, thereby enhancing the hydrogen adsorption kinetics and mass transfer process. The research findings demonstrated that the constructed three-dimensional palladium-phosphide-modified P-doped graphene material exhibited significantly higher hydrogen absorption rates in the initial 2 h compared to its two-dimensional counterparts, highlighting the advantages of the three-dimensional configuration. Specifically, the 3D Pd3P0.95/P-rGO-500 sample, calcinated at 500 °C, achieved an optimal hydrogen storage capacity of 3.79 wt% at 298 K/4 MPa. The thermodynamic stability of the structure was confirmed by molecular dynamics simulations, which also revealed an adsorption energy of −0.59 eV/H2 for a single H2 molecule, falling within the ideal range for efficient hydrogen adsorption/desorption. The significance of this research lies in its addressing the need for improved graphene-based hydrogen storage to overcome the limitations of pure graphene in hydrogen storage. By exploring three-dimensional configurations, this study opened up new possibilities for the development of efficient hydrogen storage systems and advanced the progress of hydrogen-based energy technologies. The innovative approach presented in this study has the potential to contribute significantly to the advancement of hydrogen-based energy systems, offering a promising avenue for further research and development in this field.In conclusion, this study presented a highly innovative approach to the development of hydrogen storage materials by preparing a three-dimensional configuration of palladium-phosphide-modified P-doped graphene (3D Pd


These elements act as open platforms for recruiting both positive- and negative-acting transcription factors, and as such, chromatin accessibility is an important signature for their identification.The genetic information contained in the genome of an organism is organized in genes and regulatory elements that control gene expression. The genomes of multiple plants species have already been sequenced and the gene repertory have been annotated, however, cis-regulatory elements that have been functionally validated in wheat, and a good correlation between normalized accessibility and gene expression levels.In this work we developed a transgenic INTACT [isolation of nuclei tagged in specific cell types] system in tetraploid wheat for nuclei purifications. Then, we combined the INTACT system together with the assay for transposase-accessible chromatin with sequencing [ATAC-seq] to identify open chromatin regions in wheat root tip samples. Our ATAC-seq results showed a large enrichment of open chromatin regions in intergenic and promoter regions, which is expected for regulatory elements and that is similar to ATAC-seq results obtained in other plant species. In addition, root ATAC-seq peaks showed a significant overlap with a previously published ATAC-seq data from wheat leaf protoplast, indicating a high reproducibility between the two experiments and a large overlap between open chromatin regions in root and leaf tissues. Importantly, we observed overlap between ATAC-seq peaks and We have developed and validated an INTACT system in tetraploid wheat that allows rapid and high-quality nuclei purification from root tips. Those nuclei were successfully used to performed ATAC-seq experiments that revealed open chromatin regions in the wheat genome that will be useful to identify cis-regulatory elements. The INTACT system presented here will facilitate the development of ATAC-seq datasets in other tissues, growth stages, and under different growing conditions to generate a more complete landscape of the accessible DNA regions in the wheat genome.The online version contains supplementary material available at 10.1186/s12870-023-04281-0. During the last 20 years, the significant progress in DNA sequencing technologies has allowed the rapid sequencing of complete genomes from multiple species, including a large number of varieties within each species. Today we have good reference genomes and pangenomes for the principal crop species, and that information has been critical to understand the genetic basis of biological processes, to identify natural variation responsible for phenotypic diversity, and for other applications.cis-regulatory elements and modules, which represents an important gap in our understanding of genome functionality . The re) genome , 3.Epigenome maps have contributed to the identification of regulatory regions, which are characterized by specific chromatin marks or signatures –6. AnothOryza sativa L.), maize, and Arabidopsis thaliana (L.) Heynh . Those nd wheat –22.An important parameter to assess chromatin accessibility in all these methods is the quality of the cell nuclei isolations. Broken DNA generated during extraction reduces signal/noise ratio and reduces the ability to detect open chromatin regions, so it is critical to start these experiments with high quality chromatin . For ATAHigh quality ATAC-seq data was recently reported in wheat using nuclei isolated from leaf protoplast . HoweverTriticum turgidum subsp. durum (Desf.) Husn.) and showed that it can be used to purify nuclei using a simple and rapid protocol. We then combined our INTACT system with an ATAC-seq protocol and tested different conditions to optimize enrichment of open chromatin regions. Finally, we generated INTACT-ATAC-seq data from wheat root tip samples from frozen and fresh material. Our root ATAC-seq results showed good reproducibility and enrichment of open chromatin regions in intergenic and promoter regions, which is expected for regulatory elements. A similar distribution of accessible DNA was observed when we re-analyzed published wheat ATAC-seq data generated from wheat leaf protoplast , 40 ml dH2O, 25 ul β-mercaptoethanol and 250ul 0.5 M spermidine, and keep on ice until used. After collection, the root tips were transferred to a weigh boat on ice containing 1 mL of ice-cold 1X CB, and chopped for 2.5 min using a sharp razor blade. The resulting extract was decanted into a 50 mL Falcon tube. Next, 2 mL of 1X CB were added to the samples and chopped again for 2 min. The extracts were combined to a final volume of ~ 4 mL, filtered through one layer of Miracloth and centrifuged in 50 mL tubes for 7 min at 1000 g at 4 °C. The nuclei pellets were carefully resuspended in 3 mL 1X CB using a wide-bore pipet tip to reduce mechanical shearing, and divided into two 2 mL-tubes (1.5 mL extract per tube). In parallel, 50 µL/per sample of Streptavidin Dynabeads (NEB S1420S) were pre-washed in 1X CB, of which 30 µL were added to each tube having the nuclei extract. The tubes with the bead-extract mix were placed in a rotator and incubated for 30 min at 4 °C with gentle rotation. Then, the tubes were incubated for 10 min in a magnet and the supernatant removed. Next, 1.8 mL of fresh ice-cold 1X CB + triton (to 50 ml of fresh 1X CB add 2.5 ml of 20% Triton X) were added to the tubes, which were rotated for 5 min at 4 °C, incubated in a magnet for 5 min and the supernatant removed. This procedure was repeated two more times, and finally the bead-bound nuclei were resuspended in 500 µL of 1X CB and placed on ice until transposition. Freshly purified nuclei in 1X CB to be used for ATAC-seq were kept on ice prior to the transposase integration reaction and never frozen.Our biotin labeled nuclei isolation protocol is an adaptation of a previous protocol from Queitsch Lab  [A + B + Unassigned], chloroplast (MH051715.1), and mitochondria (MH051716.1) genomes using bwa v0.7.15. Leaf protoplast ATAC-seq data  was geneAggregate plots of per base TN5 insertion counts (Fig. To compare the relative accessibility and the expression level of the genes, we stratified genes by expression level using previously published RNA-seq for root at “First leaf through coleoptile” stage, and leaf at “3 leaves unfolded” stage . FPKMs wAdditional file 1:Figure S1. Validation of INTACT system in tetraploid wheat Kronos.Additional file 2:Figure S2. Effect of the number of sequencing reads on the detected ATAC-seq peaks.Additional file 3:Table S1. Sequencing stats.Additional file 4: Table S2. Intact results and distribution in different genome regions.Additional file 5:Table S3. Overlap between peaks from fresh and frozen roots ATAC-seq data. Additional file 6: Table S4. Primers used in this study.Additional file 7:Table S5. Expression of genes associated with ATAC seq peaks in different tissues.


The prepared samples are named G50-1B to 3B and G100-1B and G100-2B. The prepared GO and graphenes were also analyzed under various characterization techniques to confirm their morphology and structural integrity. The obtained results suggest that the ORR electrocatalytic activity of graphene may differ based on the pyrolysis conditions. We found that G100-1B  and G100-2B  displayed better electrocatalytic ORR activity, as did Pt/C electrode . These results display the wide use of the prepared graphene for ORR and also can be used for fuel cell and metal–air battery applications.Graphene is a well-known two-dimensional material with a large surface area and is used for numerous applications in a variety of fields. Metal-free carbon materials such as graphene-based materials are widely used as an electrocatalyst for oxygen reduction reactions (ORRs). Recently, more attention has been paid to developing metal-free graphenes doped with heteroatoms such as N, S, and P as efficient electrocatalysts for ORR. In contrast, we found our prepared graphene from graphene oxide (GO) by the pyrolysis method under a nitrogen atmosphere at 900 °C has shown better ORR activity in aqueous 0.1 M potassium hydroxide solution electrolyte as compared with the electrocatalytic activity of pristine GO. At first, we prepared various graphene by pyrolysis of 50 mg and 100 mg of GO in one to three alumina boats and pyrolyzed the samples under a N Over the past few decades, oxygen-related electrocatalysis has garnered attention, and much work has been performed to reduce the need for noble metal catalysts or create new, alternative catalysts . To obta2-hybridized carbon atoms [2 g−1 and electrical conductivity, better thermal conductivity of 5000 W−1 K−1, optical transmittance (97.7%), Young’s modulus of 1.0 TPa, and intrinsic mobility of 200,000 cm2 v−1 s−1 [Graphite is a cheap carbon-based material that can be readily converted to highly valuable and accessible materials by chemical and thermal treatments ,9. Graphon atoms ,11. Grap4, were used in chemical reduction [Numerous uses for graphene-based materials are found in the fields of energy conversion and storage, construction, health, and the environment. Several routes also exist for obtaining graphenes, such as the exfoliation of graphite, chemical vapor deposition, solvothermal synthesis, the micromechanical cleavage of graphite, and epitaxial growth on an electrically insulating surface ,12. To meduction . On the eduction ,14. Moreeduction . The oxieduction ,14. The eduction ,14,15. MRecently, graphene and carbon-based materials were used largely as an electrocatalyst for ORR ,18,19,20In this work, we synthesized GO from graphite by modifying Hummer’s method according to the report method with partial changes in the experimental conditions ,39. To o2S2O8, ≥99.0%), phosphorus pentoxide , potassium hydroxide (KOH) powder, Nafion™ perfluorinated resin solution, and anhydrous ethanol were purchased from Sigma-Aldrich Inc. . Sulfuric acid  and hydrochloric acid  was bought from Matsuneon Chemical Ltd. . Potassium permanganate  was supplied by Katayama Chemical Industries Co., Ltd. . Hydrogen peroxide  was obtained from Junsei Chemical Co., Ltd. . Double deionized water was used in all experiments. All chemicals were used without further purification.Graphite powder , potassium persulfate  of nitrogen (N2)  . The qua−1 and 400 and 3300 cm−1, respectively. X-ray photoelectron spectroscopy (XPS) was utilized to acquire information regarding the surface’s chemical state . The CASA XPS software was used to perform peak-fitting analyses and quantitative observations. An electrochemical workstation and rotating ring-disk electrode device  with a three-electrode electrochemical cell was used to perform the cyclic voltammetry (CV), linear sweep voltammetry (LSV), and ring-disk electrodes performance at 25 °C. A catalyst sample served as the working electrode while a saturated calomel electrode (SCE) and a graphite rod served as the reference and counter electrodes.The surface morphology of the samples was analyzed by the use of field emission scanning electron microscopy  and field emission transmission electron microscopy . The samples were evenly put on carbon tape and platinum coated on the substrate before the measurement. The sample was dispersed in ethanol and loaded on a copper grid and dried before measuring with FETEM. An X-ray diffractometer  equipped with a Cu anode material and operating at 40 kV in the scanning range of 5–80° 2θ was used to determine the crystalline phase of the samples. Both Fourier transform infrared spectroscopy , Easton, MD, USA) and Raman spectroscopy were able to validate the presence of functional groups in graphene and GO (RAMANtouch). Recordings of FTIR and Raman spectra were made using a scanning range of between 400 and 4000 cmcat.cmdisk−2, catalyst inks were dripped over the polished glassy carbon-based rotating ring-disk electrode  and allowed to dry at 60 °C overnight. After this, the ORR activity and electron selectivity of the catalysts were evaluated. The electrocatalytic ORR activity was measured at a scan rate of 10 mV s−1 in a N2 or oxygen (O2) saturated 0.1 M aqueous KOH solution (pH = 13).The catalyst ink was created by sonicating 5 mg of catalyst powder with 140 µL of anhydrous ethanol, 140 µL of deionized water, and 20 µL of 5% Nafion solution for 30 min. Before beginning the electrochemical test, the working electrodes  of the RRDE were finished with an application of alumina slurry to smooth out any rough edges. After pipetting 7.0 µL of the ink containing a catalyst loading of ~0.117 mgUsing the following equation (1), all potentials were calibrated to a reversible hydrogen electrode ,26.E, bulk oxygen concentration (1.2 × 10−6 mol cm−3 for 0.1 M KOH solution), oxygen diffusion coefficient (1.9 × 10−5 cm2 s−1), and kinetic viscosity of the electrolyte (0.01 cm2 s−1 for 0.1 M KOH solution).The Koutecky–Levich equation can be used to calculate the number of electron transfers per oxygen molecule involved in oxygen reduction based on Equations (2)–(4) ,26.(2)1The surface morphology of GO and graphene were shown in Transmission electron microscopy (TEM) is another useful tool for determining the quality of exfoliated graphene. The FETEM image of a graphene sheet shown in It is well known that pure graphite has a major X-ray diffraction (XRD) peak at 2θ = 26.5° and a subtle peak at 2θ = 54.5° . These p−1 and 1588 cm−1, as well as the other functional groups such as hydroxyl , methyl , epoxy C-O-C (1222 cm−1), and C-O (1042 cm−1), respectively  and G (1585 cm−1) bands of the graphene’s Raman spectra , which was indicative of a rising trend for G50-1B (1.21), G100-1B (1.15) and also illustrates the growth of sp2 clusters and the potential for the creation of further graphitic domains [Raman spectroscopy is a crucial tool for characterizing carbon materials because it can tell the difference between single-layer and multi-layered graphene, as well as the size and degree of disorder in the crystals . Figure is of GO . The D bis of GO ,41. The onal way ,41. The  spectra b,c [14,4 spectra b,c. The  the D 13 cm−1 and2 carbon (C-C), ether (C-O-C), carbonyl carbon (C=O), and carboxylate carbon (O-C=O) at 284.8 eV, 286.82 eV, 288.3 eV, and 289.7 eV, respectively  showed two major bands at 285 eV and 532 eV which are due to the presence of the C 1S and O 1s functional groups in the samples . We performed cyclic voltammetry (CV) and linear sweep voltammetry (LSV) to predict and confirm the preliminary electrocatalytic ORR activity. These methods are very useful and straightforward to provide a clear view of the electrocatalytic activity of the prepared electrocatalysts and their effectiveness in electron transfers.Recently, carbon-based ORR electrocatalysts that don’t rely on any metals have been proven to be viable low-cost alternatives to platinum-based catalysis because of their stability, accessibility, environmental acceptability, and surface properties ,23,46. A2-saturated aqueous 0.1 M KOH electrolyte (pH = 13)  and half-wave potential (E1/2) are the two major parameters used to predict the performance of electrocatalysts for ORR. The CV and LSV graphs of GO under the O2-saturated 0.1 M KOH electrolyte display the occurrence of a reduction peak as compared to the GO electrocatalysts under a N2-saturated electrolyte  values of 0.797, 0.664, and 2.254, respectively. The pyrolysis of GO at 900 °C has shown different ORR responses based on the number of boats kept during the thermal annealing process. G50-1B displayed a better ORR response with Eonset and E1/2 of 0.802 and 0.656 as compared to G50-2B (Eonset and E1/2 of 0.785 and 0.640) and G50-3B (Eonset and E1/2 of 0.763 and 0.618) of GO together at the pyrolysis temperature at 900 °C. Likewise, G50-1B (4.797) presented a higher JL value as compared to G50-2B (3.500) and G50-3B (3.019). The use of 50 mg of GO in a single boat in a tubular furnace would facilitate the uniform transfer of heat throughout the alumina boat, and the pyrolysis process also occurred uniformly on the GO, whereas the introduction of two or three boats (each 50 mg of GO) together would reduce the effectiveness of heat dissipation throughout the samples which may slightly alter graphene preparation and their properties so that the ORR performance is also reduced when introducing more than one boat during the pyrolysis process.At first, we carried the CV of the prepared electrocatalysts such as GO, G50-1B, G50-2B, G50-3B, G100-1B, and G100-2B, respectively, at the NpH = 13) A. The LS results C. It is mosphere . We alsoctrolyte B,D. Thisonset, E1/2, and JL values of 0.843, 0.774, and 4.558, respectively) and G100-2B , with a more positive onset potential and stable reduction of oxygen taking place for these electrocatalysts. The electron transfer number was predicted from the LSV carried out at various rotations per minute  at the O2-saturated aqueous 0.1 M KOH electrolyte. The LSV graphs of GO, G50-1B-3B performed at different rpms indicated the three stages of ORR activity in O2-saturated aqueous 0.1 M KOH electrolyte which indicates fairly lower performance in ORR activity  from the LSV graphs performed at different rpms. The slopes of the K-L plots can be used to calculate the number of transferred electrons (n) involved in oxygen reduction as shown in n values of GO, GX 1B, GX 2B, GX 3B, GY 1B, and GY 2B at 0.4 V were 1.69, 2.69, 2.54, 0.68, 3.76, and 3.41, respectively. These results proved the superior ORR activity for G100-1B and G100-2B as compared to other electrocatalysts. The G100-1B and G100-2B electrocatalytic activity can suggest that almost a direct four-electron transfer reaction occurred and may help to produce water as an end product. The better ORR activity of the optimized graphenes may be due to the presence of the higher valence orbital energies of the ORR active atom, which increases the adsorption of OOH* and OH* intermediates.The study on the Koutecky–Levich (K-L) plot is the most common method to prove the electron transfer number  and Pt/C electrocatalysts have displayed superior ORR with an n value close to four, which suggests the direct production of water during the electrocatalytic reaction.We also performed a comparison study with commercial Pt/C electrocatalysts due to the benchmark electrocatalytic activity of Pt/C electrocatalysts for ORR. The CV and LSV graphs of Pt/C electrocatalysts performed with Nctrolyte . In addient flow . The EonK-L plot . The est2 gas during the pyrolysis of GO at 900 °C may show no stronger sorption of N atoms at the graphene basal planes and edges. At the same time, we discussed the better electrocatalytic ORR activity of graphene prepared at 900 °C under a N2 atmosphere as compared with GO and rGO prepared at 250 °C may suggest some atomic-scale N atoms may exist on the graphene or that these may create some defects on the graphene which may be responsible for superior ORR activity. Using an FTIR study, it was also difficult to exactly predict the N-doping on graphene due to the presence of C-N, N-H bending, and C=C stretching peaks present at 1187 cm−1 and 1571 cm−1 that may overlap with other functional groups as explained above . We studied the effect of crystallinity and the expansion of GO under thermal annealing temperatures via XRD and also confirmed the surface property and structural behaviors under various characterization techniques. The overall study conveys the successful synthesis of GO and the effective production of graphene based on tubular furnace diameter and annealing temperatures. Our preliminary results hypothesize that the graphene production may differ based on the tubular furnace quartz tube diameter. Based on the tubular furnace quartz tube diameter the use of the alumina boat size also differs, which may affect the graphene production. Furthermore, we studied the electrocatalytic activity of GO and graphenes. We noticed excellent electrocatalytic behaviors of graphene prepared by the introduction of 100 mg of GO in one or two boats (G100-1B and 2B) at the pyrolysis temperature of 900 °C under an O2 atmosphere as compared to GO and G50-1B to 3B. We found that G100-1B  and G100-2B  displayed better electrocatalytic ORR activity similarly to Pt/C electrodes . We strongly believe that the G100-1B electrocatalytic ORR activity (without any doping) is almost closer to the electrocatalytic ORR of commercial Pt/C electrocatalysts. These findings open up wider opportunities and the graphene properties can be easily turned with slight modifications. We also hope that the ORR activity can be enhanced further by the introduction of atomic-scale noble metals or heteroatoms in prepared graphene. More detailed studies need to be performed on the optimized electrocatalyst to improve the activity further for superior electrocatalytic ORR activity. Our initial findings point to the potential utility of graphene as an electrocatalyst for ORR in fuel cells and metal–air batteries.In this work, we synthesized GO from graphite by modifying Hummer’s method followed by preparing graphene via the thermal annealing method under a N