Specific Surface Area Of Graphene Research Articles

Effect of Graphene on the Performance of Silicon-Carbon Composite Anode Materials for Lithium-Ion Batteries.

(Si/graphite)@C and (Si/graphite/graphene)@C were synthesized by coating asphalt-cracked carbon on the surface of a Si-based precursor by spray drying, followed by heat treatment at 1000 °C under vacuum for 2h. The impact of graphene on the performance of silicon-carbon composite-based anode materials for lithium-ion batteries (LIBs) was investigated. Transmission electron microscopy (TEM) and selected area electron diffraction (SAED) images of (Si/graphite/graphene)@C showed that the nano-Si and graphene particles were dispersed on the surface of graphite, and thermogravimetric analysis (TGA) curves indicated that the content of silicon in the (Si/graphite/graphene)@C was 18.91%. More bituminous cracking carbon formed on the surface of the (Si/graphite/graphene)@C due to the large specific surface area of graphene. (Si/Graphite/Graphene)@C delivered first discharge and charge capacities of 860.4 and 782.1 mAh/g, respectively, initial coulombic efficiency (ICE) of 90.9%, and capacity retention of 74.5% after 200 cycles. The addition of graphene effectively improved the cycling performance of the Si-based anode materials, which can be attributed to the reduction of electrochemical polarization due to the good structural stability and high conductivity of graphene.

Efficient Fluoride Removal from Aqueous Solution Using Graphene/Ce Composite Supported on Activated Carbon

Background: More than 260 million people worldwide are affected by excess fluoride (F- > 1.5 mg/L) in their drinking water. Fluorosis of the teeth and skeleton, among other health issues, is caused by it. Objective: The aim of this study is to evaluate the fluoride removal from contaminated water using graphene-based new adsorbent material. Method: Graphene (G) was prepared by a facile liquid-phase exfoliation method. CeO2 nanoparticles (NPs) were synthesized by the co-precipitation method. G was treated with CeO2 NPs in a probe sonicator to generate G/Ce material in solution. Finally, the impregnation evaporation process synthesized the G/Ce supported on activated carbon composite (G/Ce/AC). Results: FE-SEM analysis shows that the crumpling and scrolling sheets of G, the nanosized spherical shape of CeO2 NPs and a thick layer of nano-sized spherical particles has built up on the surface of graphene in G/Ce/AC composite. After conversion to G/Ce/AC Composite, the specific surface area of graphene was increased from 3.08 to 485.3621 m2/g. The adsorption of fluoride on G/Ce/AC was investigated using batch systems (effects of pH, contact time, adsorbent dosage and the initial fluoride concentration), adsorption isotherm and kinetic studies. The pseudo-second order was the one that best described the kinetic data, while the Langmuir isotherm best described the equilibrium data with a maximum adsorption capacity equal to 27.9 mg/g. Conclusion: Therefore, the results show that the G/Ce/AC composite was well synthesized and has excellent fluoride adsorption capacity compared to other materials already evaluated for this purpose.

Graphene hydrogel modification with 4-methylumbelliferone molecules as electrode material for supercapacitor

Graphene hydrogels (GH), as a derivative of graphene have become a research hotspot in the field of energy storage due to their three-dimensional network structure which can prevent the agglomeration of graphene. The specific capacitance and energy storage ability can be further increased by non-covalent functional graphene hydrogels with organic small molecules. In this work, 4-methylumbelliferone (DTBF) molecules interacted on the surfaces of GH via π-π interactions to get a carbon electrode material (DTBF/GH) by one-step hydrothermal. On the one hand, the DTBF molecules can contribute capacitance by faradic reactions, on the other hand, they can act as spacers to hinder the accumulation of graphene nanosheets, thus enhancing the specific surface area of graphene and promoting the migration of electrolyte ions. As a result, DTBF/GH displays an ultrahigh-specific capacitance. The specific capacitance can reach up to 578 F g−1 (1 A g−1). To verify the influence of electrode material matching on capacitor performance, an asymmetric supercapacitor and a symmetrical capacitor are assembled respectively. Although the specific capacitance of the DTBF/GH material is higher than that of activated carbon (AC), the energy density (Ed = 19 Wh kg−1) of the DTBF/GH//AC capacitors is higher than that of the DTBF/GH//DTBF/GH capacitors. It shows that the matching of electrode materials has a great influence on the Ed and the power density (Pd) of the capacitor. In addition, two DTBF/GH//AC devices in series can light 47 LEDs.

Adsorption of radon on transition metal functionalized graphene monolayer with external effects

The noble gas radon (Rn) is radioactive and can gravely harm the human body. As a result, capturing and dealing with Rn gas is an important task, in terms of radiation protection. The large specific surface area of graphene renders it a potential candidate for gas adsorption applications. Along these lines, in this work, theoretical calculations based on the density functional theory were presented to systematically explore the adsorption properties of Rn on transition metal (TM) functionalized graphene monolayer. The adsorption energies of Rn atoms on the functional graphene were estimated up to −0.873 eV, according to our computed results. The increase in the concentration of Rn atoms and the ambient temperature led to a reduction in the adsorption energy of Rn on the surface. To effectively control the adsorption characteristics, electric field and stress were externally added. The calculation results showed that a negative electric field and proper deformation could significantly improve the adsorption of Rn to TM functionalized graphene. In this work, it was demonstrated that TM functionalized graphene could be successfully used as an adsorber of Rn atoms with promising results. In addition, the adsorption properties can be controlled and enhanced under the application of an external field, as well as a stress load, which is of great significance for application in radiation protection.

Graphene - Calculation of Specific Surface Area

Purpose: Graphene is a wonder material with high potential for application in energy storage supercapacitors owing to its extremely high surface area. Here, a simple and detailed description of calculation of specific surface area of graphene is given in a tutorial like format. From geometric considerations and known values of interatomic distances, it is shown that we can estimate the theoretical surface area of graphene sheets to be ~2630 m2g-1. Using this approach, teachers will be able to educate their students in various fields where surface area is one of the important factors. Approach/Methodology: Calculation of theoretical maximum specific surface area of graphene using the data like area of a regular hexagon, C-C bond length within the layers in graphene and relative average atomic mass of carbon. Findings/Result: From geometric considerations and known value of interatomic distance in graphite, it is possible to show by calculations that the theoretical surface area of graphene sheets is ~ 2630 m2g-1. Originality/Value: It is a useful exercise for understanding the simple principles behind such calculations and to appreciate its usefulness in practical applications. Paper type: Review based Analysis.

Efficient preparation and characterization of graphene based on ball milling

Graphene has a unique two-dimensional crystal structure and excellent physical and chemical properties. It is one of the new strategic materials developed by countries around the world in the 21st century. In recent years, the method of preparing graphene by mechanical stripping is becoming mature, including oxidation reduction method, mechanical stripping method, SiC epitaxial growth method, chemical vapor deposition method, etc. Based on the ball milling method, graphene is prepared in this study using a uniform design test method, scaled graphite as the raw material, and metallic aluminum as the grinding aid while considering the influence of ball ratio, grinding time, and rotation rate. A mathematical model was established based on partial least squares regression analysis and stepwise regression analysis. The best experimental scheme was obtained through the selection and optimization of the mathematical model, and the process of efficiently preparing graphene in the laboratory was explored. The prepared products were characterized by X-ray diffractometer, automatic specific surface area and porosity analyzer, and laser confocal Raman spectrometer. The results indicate that using aluminum powder as a grinding aid can significantly improve the efficiency of ball milling, the specific surface area of graphene produced is 542.598 m2/g, with the number of layers ranging from 2 to 5 layers. It is proved that the proposed graphene preparation method can obtain graphene with better quality. The study's findings serve as a guide for the production of graphene.

A 3D nano-sandwich structure constructed by intercalation of aramid nanofibers preventing re-stack of graphene for high surface area electrode materials

In recent decades, graphene has become a popular research topic in the energy storage field, this is due to its unique physical and chemical properties, particularly as electrode material for supercapacitor and battery. The excellent electrical conductivity and high specific surface area of graphene are crucial points to its implementation as active material in energy storage devices. Nevertheless, the graphene’s re-stack is an inevitable technological problem, causing the graphene’s many excellent properties to decrease sharply. In this work, aramid nanofibers as non-conductive and non-capacity were assembled with graphene to prevent the re-stacking phenomena and establish a 3D nano-sandwich structure, which provides more surface area for energy storage. Compared with pristine graphene, the prepared aramid nanofibers and the graphene assembled electrode material showed highest capacity of 285.5 F g−1 at 0.5 A/g with good cycling stability of 81 % over 10, 000 cycles. This significant finding proves that the modification of graphene based-aramid nanofiber composite is an effective strategy in order to the prevent graphene’s re-stack and promote the electrochemical performance.

Few-Layer Graphene As an Electrode, Electrode Additive and an Interfacial Layer in Aqueous Supercapacitors

The intermittent nature of many renewable energy sources such as wind and solar, coupled with fluctuations in energy demand, creates a pressing need for efficient, low-cost energy storage technologies. Supercapacitors are promising candidates to play a role in next-generation energy storage systems. They have a higher power density and better cycle life (although lower energy density) than batteries making them ideal for rapid energy storage and deployment [1]. Activated carbon is a favoured electrode material due to high surface area, although low conductivity requires use of a conductive additive (often carbon black), reducing available surface area for charge storage. In contrast, the high conductivity and specific surface area of graphene has made it a promising material for electrochemical double layer supercapacitors (EDLCs) [2], however, performance is limited by restacking of the graphene sheets, reducing available surface area.In this work, high-shear exfoliated few layer graphene (FLG) [3] is investigated both as an electrode material and as a conductive additive/interfacial layer for EDLCs. FLG suspensions were produced under a variety of exfoliation conditions, with platelet thickness and linear dimension determined from Raman spectroscopy based on metrics developed by Backes et al. [4] and through scanning electron microscopy (SEM).The FLG suspensions were used in three ways: i) to create thin ‘graphene paper’ electrodes; ii) as a conductive additive, mixed into the activated carbon electrode material; iii) deposited onto the back of (and diffused within) activated carbon electrodes. These electrodes were investigated by Raman spectroscopy and Scanning Electron Microscopy, before being assembled into symmetric two-terminal aqueous cells then evaluated by cyclic voltammetry (CV), galvanostatic charge/discharge (GCD), and electrochemical impedance spectroscopy (EIS), and their electrochemical performance related to structure and composition.As expected, pure FLG electrodes often showed excellent low series resistance values, however specific capacitance was low, due to restacking. Directly mixing 5% FLG into activated carbon as a conventional conductive additive led to a specific capacitance of 63 F/g (from CV at 10 mV/s), and a series resistance of 19 W (from GCD at 1 A/g) - markedly inferior to those with 5% carbon black as a conductive additive (95 F/g and 2 Ohm) and inferior even to electrodes with no conductive additive (87 F/g and 10 Ohm).However, post fabrication deposition/infusion of FLG offers comparable performance to carbon black (90 F/g and 1 Ohm) at 7% FLG by weight. As the quantity of FLG is increased the specific capacitance decreases sharply. This behaviour is attributed to FLG restacking on the rear of the electrode, so adding mass whilst providing limited additional capacitance, and compression of the electrode.Adding high-shear exfoliated FLG to activated carbon electrodes shows promise for obtaining the benefits of both materials. At present, FLG/activated carbon electrodes can match the performance of those produced from activated carbon with a carbon black conductive additive and, with further optimization, we expect will be able to exceed them.Figure: a) Cross sectional SEM image of activated carbon electrode with graphene interfacial layer; b) magnified cross sectional SEM image of graphene interfacial layer; c) cyclic voltammograms at 10 mV/s of the different electrodes mentioned in the abstract.

Ethanol Electro-Oxidation on Catalysts with S-ZrO2-Decorated Graphene as Support in Fuel Cell Applications.

Direct ethanol fuel cells (DEFCs) are considered the most suitable direct alcohol fuel cell (DAFC) in terms of safety and current density. The obstacle to DEFC commercialization is the low reaction kinetics of ethanol (C2H5OH) oxidation because of the poor performance of the electrocatalyst. In this study, for the first time, graphene nanoplates (GNPs) were coated with sulfated zirconium dioxide (ZrO2) as adequate support for platinum (Pt) catalysts in DEFCs. A Pt/S-ZrO2-GNP electrocatalyst was prepared by a new process, polyol synthesis, using microwave heating. Field emission scanning electron microscope (FESEM) imaging revealed well-dispersed platinum nanoparticles supported on the S-ZrO2-GNP powder. Analysis of the Fourier transform infrared (FTIR) spectrometry confirmed that sulfate modified the surfaces of the sample. In X-ray diffraction (XRD), no effect of S-ZrO2 on the crystallinity net in Pt was found. Pt/S-ZrO2-GNP electrode outperformed those with unsulfated counterparts, primarily for the higher access with electron and proton, confirming sulfonating as a practical approach for increasing the performance, electrocatalytic activity, and carbon monoxide (CO) tolerance in an electrocatalyst. A considerable decrease in the voltage of the CO electrooxidation peak from 0.93 V for Pt/C to 0.76 V for the Pt/S-ZrO2-GNP electrode demonstrates that the new material increases activity for CO electrooxidation. Moreover, the as-prepared Pt/S-ZrO2-GNPs electrocatalyst exhibits high catalytic activity for the EOR in terms of electrochemical surface area with respect to Pt/ZrO2-GNPs and Pt/C (199.1 vs. 95 and 67.2 cm2.mg−1 Pt), which may be attributed to structural changes caused by the high specific surface area of graphene nanoplates catalyst support and sulfonating effect as mentioned above. Moreover, EIS results showed that the Pt/S-ZrO2-GNPs electrocatalyst has a lower charge transfer resistance than Pt/ ZrO2-GNPs and Pt/C in the presence of ethanol demonstrating an increased ethanol oxidation activity and reaction kinetics by Pt/S-ZrO2-GNPs.

Removal of Sb(III) by 3D-reduced graphene oxide/sodium alginate double-network composites from an aqueous batch and fixed-bed system

We created 3D-reduced graphene oxide/sodium alginate double network (GAD) beads to address the problem of local water pollution by antimony. GAD is a novel material with the high specific surface area of graphene and biosecurity of sodium alginate. Due to the introduction of graphene, the thermal stability and specific surface area of GAD are enhanced, as shown from the FTIR, TGA, BET, Raman, and XRD characterizations. The influence of different environmental variables-such as the pH, dosage, temperature, contact time, and sodium chloride concentration on the Sb(III) sorption with GAD-was investigated. The adsorption results fit well with both the pseudo-second order (R2 > 0.99) and Freundlich (R2 > 0.99) isotherm models. The temperature rise has a negative influence on the adsorption. The Langmuir adsorption capacity is 7.67 mg/g, which is higher than many adsorbents. The GAD results from the fixed-bed adsorption experiment were a good fit with the Thomas model (R2 > 0.99). In addition, GAD appears to be a renewable and ideal adsorbent for the treatment of antimony pollution in aqueous systems.

Ultra-Sensitive Electrochemical Determination of Carcinoembryonic Antigen by a Sandwich Immunosensor Graphene Oxide (GO)-Gold Substrate and a Silver-Coated Bovine Serum Albumin (BSA)-Platinum Nanocomposite on a Glassy Carbon Electrode (GCE)

An ultra-sensitive electrochemical immunosensor for detecting carcinoembryonic antigen was prepared. Graphene oxide-gold was used as the substrate modifier of the sandwich immunosensor. The high conductivity of graphene oxide effectively enhanced the electron transfer rate. The large specific surface area of graphene and the biocompatibility of gold nanoparticles increased the number of primary antibodies. The bovine serum albumin coated silver – platinum composite was used as a secondary antibody tag to prepare signal probes. The excellent biocompatibility of bovine serum albumin increased the number of secondary antibody connections. Silver nanoparticles increased the speed of electron transfer, and platinum further enhanced electrochemical sensing capabilities by catalyzing hydrogen peroxide. The immunosensor showed good performance for detecting carcinoembryonic antigen. Under the optimal conditions, the dynamic response range for carcinoembryonic antigen was from 0.005 ng·mL−1 to 100 ng·mL−1 with a detection limit of 0.76 pg·mL−1. The immunosensor also shown high selectivity, suitable stability, and good reproducibility, which provides new capabilities for clinical carcinoembryonic antigen detection.

Graphene-based Composites for the Thermal Decomposition of Energetic Materials

Owing to its remarkable mechanical, electrical and thermal properties, graphene has been a hot area of composites research in the past decade, including the field of energetic materials. Graphene has been widely applied in enhancing the physical properties of energetic materials, such as solid composite propellants. Through the way of adding different forms of graphene into the matrix of solid propellants, their thermal decomposition performance can be effectively improved. In this paper, we reviewed the status and challenges of the application of graphene in the thermal decomposition of composite solid propellant. Moreover, the main preparation methods and material structures of graphene are reviewed. We can conclude that graphene and its derivatives can enhance the catalytic effect remarkably, which can be attributed to the large specific surface area of graphene that makes the uniformly dispersed catalyst particles and the more catalyst active sites. Meanwhile, graphene possesses the high thermal conductivity, making the rapider heat diffusion, which can promote the decomposition reactions of the energetic components in solid propellants. Graphene and catalyst work synergistically in their thermal decomposition. More than this, the main methods to improve the thermal decomposition of energetic components of composite propellants and their effects on decomposition temperature reduction are systematically summarized, respectively.

Graphene Sensor for Future Local Economic Development: A Review

Graphene, a family of carbon has been known as a superior material of both conducting and transparent. Therefore, graphene is very promising material for many applications on microelectronics and nanotechnology. The structural, thermal, optical and electrical properties of the graphene were also potential to be applied on sensor. Graphene is the most recognized nanoparticle for fabrication of biomedical sensors due to its stimulating qualities such as excellence aqueous process ability, functional surface properties, surface-enhanced Raman scattering, cell growth ability, and good biocompatibility. Due to the high specific surface area of graphene, it was very excellent material for gas sensor application. The outstanding properties of graphene were also led to increasing the demand of graphene every year which is dominated by China (70%), India (14%), and Canada (2%). Moreover, current marketplace of graphene was also dominated for academic research, super capacitor, ITO, and sensor. Every year, the market of graphene sensor is continuously increasing. This trend reveals graphene-based sensors very promising commodity for future technology. The present study highlights the state of art review and potential future local economic development of graphene for use as sensors.

Effects of graphene addition on the refinement of silicon phase in graphene/A356.2 composites

The coarse silicon phase makes the mechanical properties of the A356.2 alloy difficult to meet the needs of high-standard components. The influence of graphene addition on the silicon phases refinement and mechanical properties of the graphene/A356.2 composites prepared by stirring casting method was elucidated. Due to the refinement rate of silicon phase of the 0.5 wt% graphene/A356.2 composites (3.59 μm) reached 55.5%, the ultimate tensile strength (UTS: 383.3 MPa), yield strength (YS: 313.4 MPa) and elongation (EL: 5.0%) were increased by 47.4%, 44.3% and 400.0%, respectively. The refinement of silicon phase was mainly attributed to the unique two-dimensional structure and large specific surface area of graphene, which provided an effective nucleation core of the silicon phase during solidification process.

Defect-Rich Co-CoOx -Graphene Nanocatalysts for Efficient Hydrogen Production from Ammonia Borane.

Chemical hydrogen storage ammonia borane has attracted extensive attention as a method of efficient utilization of hydrogen energy. The high-efficiency catalysts are the main factor restricting the hydrogen production of ammonia borane. In this paper, the synergistic effect of Co and CoOx supported on graphene (named Co-CoOx @GO-II) promotes the efficient hydrogen production of ammonia borane, and its catalytic hydrogen production rate can reach 5813 mL min-1 gCo -1 at 298 K, the corresponding TOF is 15.33 min-1 . After five stability tests, Co-CoOx @GO-II maintained 65% of its original catalytic performance. The synergy of metal and metal oxide and the defects in the atomic arrangement ensure the catalytic activity, the large specific surface area of graphene ensures the dispersion and fixation. This strategy may provide a possibility to design high-performance transition metal catalysts.

High-content graphene nanoplatelet reinforced aluminum composites produced by ball milling and hot extrusion

Due to the high specific surface area of graphene, the effective incorporation of high-content graphene in metals is challenging. Here, aluminum composites with graphene nanoplatelet (GNP) content up to 5.0 vol% were prepared by spark plasma sintering (SPS) of blended powders with various ball milling regimes and subsequent hot extrusion. The effects of GNP distribution state on the properties of GNP/Al composite were investigated. 5.0 vol% GNPs were uniformly dispersed in aluminum matrix by high-speed ball milling (HSBM) process, but with damage GNPs due to the too high energy input. By contrast, the wellstructured and dispersed GNPs in aluminum powders were obtained via shift-speed ball milling (SSBM). The clear GNP-Al interface in extruded SSBM composite was attributed to well-structured GNPs. As a result, the yield strength (YS) and ultimate tensile strength (UTS) of composite produced by SSBM reached 279 and 303 MPa, which are 166% and 116% higher than those of monolithic Al. This demonstrated that it may be promising to introduce high-content GNPs with tailorable interface in Al alloys via modified ball milling technique and hot extrusion.

Vertically Aligned Graphene Prepared by Photonic Annealing for Ultrasensitive Biosensors.

Graphene exhibits excellent physical, electronic, and chemical properties that are highly desirable for biosensing applications. However, most graphene biosensors are based on graphene lying flat on a substrate and therefore do not utilize its maximum specific surface area for ultrasensitive detection. Herein, we report the novel use of photonic annealing on a flexographically printed graphene-ethyl cellulose composite to produce vertically aligned graphene (VAG) biosensors for ultrasensitive detection of algal toxins in drinking water. These VAG structures, which maximized the specific surface area of graphene, were formed by partial removal of the polymeric binder upon applying intense pulsed light on the printed graphene. A label-free and low-cost VAG biosensor based on a non-faradaic electrochemical impedance spectroscopy technique was fabricated. The biosensor exhibited a limit of detection of 1.2 ng/L for microcystin-LR in local tap water. Such an ultrasensitive VAG biosensor is suitable for low-cost mass production using an integrated roll-to-roll flexographic printing with rapid photonic annealing technique.

Electrochemical method for determination of levodopa in the presence of uric acid using In2S3 nanospheres on 3D graphene-modified ITO glass electrode

An electrochemical sensor that can sensitively detect levodopa without fragile and expensive antibodies has been prepared on the basis of indium sulfide and graphene. The indium sulfide nanospheres synthesized by a hydrothermal method were grown on the surface of three-dimensional graphene prepared by chemical vapor deposition. The graphene maintains a good 3D structure and the indium sulfide nanospheres increases the specific surface area of graphene. The composite possesses a low detection limit of 87 nM (S/N = 3) and the sensitivity of it reaches 1.98 μA μM−1 cm−1. Also, good electrochemical performance, selectivity, and stability make it available to be used for detecting real biomolecules.

Acetylcholinesterase electrochemical biosensors with graphene-transition metal carbides nanocomposites modified for detection of organophosphate pesticides.

An acetylcholinesterase biosensor modified with graphene and transition metal carbides was prepared to detect organophosphorus pesticides. Cyclic voltammetry, differential pulse voltammetry, and electrochemical impedance spectroscopy were used to characterize the electrochemical catalysis of the biosensor: acetylcholinesterase/chitosan-transition metal carbides/graphene/glassy carbon electrode. With the joint modification of graphene and transition metal carbides, the biosensor has a good performance in detecting dichlorvos with a linear relationship from 11.31 μM to 22.6 nM and the limit of detection was 14.45 nM. Under the premise of parameter optimization, the biosensor showed a good catalytic performance for acetylcholine. Compared to the biosensors without modification, it expressed a better catalytic performance due to the excellent electrical properties, biocompatibility and high specific surface area of graphene, transition metal carbides. Finally, the biosensor exhibits good stability, which can be stored at room temperature for one month without significant performance degradation, and has practical potential for sample testing.

Heterostructure arrays of NiMoO4 nanoflakes on N-doping of graphene for high-performance asymmetric supercapacitors

Supercapacitors, as a clean and sustainable power supply, have been a popular subject of research in the field of energy storage owing to their excellent electrochemical performance. As an important part of supercapacitors, electrode materials and structures have been continuously designed and improved. This study presents a facile synthesis of an N-doping of graphene/NiMoO4 (NG/NiMoO4) heterostructure for electrochemical supercapacitors. By combining excellent conductivity, large specific surface area of graphene, and reversible redox of metal oxide, this hybrid composite exhibits an ultrahigh specific capacitance of 1913 F/g at 1 A/g. Using NG/NiMoO4 as positive electrode and active carbon as negative electrode, an asymmetric supercapacitor was assembled. The device exhibits a high capacitance of 62.5 F/g at 0.5 A/g, a maximum energy density of 22.2 Wh/kg at the power density of 400 W/kg, and excellent cycling stability (94.2% retention after 5000 cycles). The results demonstrate that the NG/NiMoO4 composite is a promising electrode material for supercapacitors in energy storage applications.