KOH Electrolyte Solution Research Articles

Petroleum coke derived reduced graphene oxide as an electrocatalyst for water splitting

One of the by-products produced in the petroleum refinery industry is Petroleum coke or pet coke (PC). To make its use in the development of high-cost value-added carbon products apart from electrodes in steel and aluminium extraction is one of the areas of research interest among the scientific community. The present investigation optimized processing parameters to synthesize graphene oxide (GO) using the well-known Hummers method from different heat treated (450 °C, 1400 °C, and 2200 °C) PC. The derived GO was thermally reduced into the reduced GO (rGO). Both GO and rGO were characterized by various spectroscopic techniques to ascertain ultimate GO and rGO synthesis. The FE-SEM images demonstrated that the surface morphology of the GO and rGO is highly exfoliated and has a thin sheet-like structure that is synthesized from 2200 °C heat-treated PC. The HR-TEM image shows a few layers of sheet-like structure for both GO and rGO and the SAED pattern shows fused for GO and the hexagonal ring pattern for rGO, indicating the presence of both amorphous and crystalline structures. The obtained rGO possesses a low band gap (2.45 eV) that is attributed to the semiconducting behavior. BET analysis reveals that synthesized GO possesses a decent specific surface area (211.2 m2/g). The upshot shows that PC has the potential to replace the costly natural graphite for the synthesis of GO and rGO having excellent properties. The obtained rGO demonstrates excellent bifunctional electrocatalyst materials for hydrogen and oxygen evolution reactions (HER and OER). The rGO/Ni-Foam electrode shows a low overpotential of 169 mV for HER and 400 mV for OER at 10 mA/cm2 current density in 1.0 M KOH electrolyte solution along with the lowest Tafel slope of 108.23 mV/dec and 104 mV/dec for HER and OER respectively shows faster kinetic rate towards water splitting. This study displays the vast possibility of utilizing PC to synthesize value-added products and its application as an electrocatalyst.

Performance of Co–Co(OH)2 coated nickel foam as catalysts for the hydrogen evolution reaction under industrially relevant conditions

In the present work, we employed a customised electrolyser test cell to quantify the electrocatalytic activity of a high-performing Co–Co(OH)2/nickel foam electrocatalyst, towards the hydrogen evolution reaction (HER) under industrial-relevant alkaline electrolysis conditions. The Co–Co(OH)2 electrocatalyst was synthesized by a wet chemical deposition route followed by thermal decomposition, fully covering the nickel foam support. In conventional 3-electrode tests, the synthesized Co–Co(OH)2 electrocatalyst revealed a 78 mV overpotential at 10 mA cm−2 exhibiting a promising performance compared to the 290 mV measured for pristine nickel foam. Further testing under industrial-relevant conditions with a customised electrolyser cell configuration proves that the electrocatalysts lower the cell potential by 200 mV at 200 mA cm−2 compared to pristine nickel foam after 118 h of electrochemical measurements at 80 °C using a 30 wt% KOH electrolyte solution. These findings indicate that the high performance achieved for the Co–Co(OH)2 electrocatalyst could potentially be translated to industrial-relevant environments.

Preparation and electrochemical characteristics of porous carbon composites originating from hyper-crosslinked polymers

A method of hyper-crosslinked polymers-derived carbon compounded with transition metal sulfides was employed in this study for suppressing the severe disadvantage of specific capacitance (SC) decay of transition metal sulfides due to volume variation and to enhancing supercapacitors' performance from the perspectives of power density and energy density, with the aim of addressing the challenge that carbon-based supercapacitors exhibit relatively lower energy density (ED). In this study, PNOC-800-3@NiS composites were well prepared based on the direct carbonization-chemical activation method with hyper-crosslinked polymer (PNO) as the precursor. Subsequently, PNOC-800-3@NiS composites were well prepared based on the hydrothermal approach with thiourea and PNOC-800-3 as the sulfur source and the substrate, separately. The effects exerted by different nickel-sulfur ratios and synthesis temperatures on the composites' electrochemical characteristics were studied. As revealed by the results, the surface area of PNOC-800-3@NiS-2-180 reached 1006.31 m2 g−1, and the pore diameter on average was 1.86 nm at the ratio of nickel to sulfur of 1:2 and the synthesis temperature of 180 °C. In the 6 M KOH electrolyte solution, composites exhibited the SC of 1051.2 F g−1 under a current density (CD) of 1 A g−1. With the rising CD in a range between 1 A g−1 and 10 A g−1, SC achieved a decay rate of 49.58 %. Under a power density (PD) of 700 W kg−1, a prominent ED was achieved by the assembled asymmetric supercapacitor, which was of 20.98 Wh kg−1. When 5000 cycles of discharging and charging was achieved, the composite PNOC-800-3@NiS-2-180 exhibited a capacitance retention rate of 72.63 %. Furthermore, as indicated by the result, the composite PNOC-800-3@NiS-2-180 exhibited prominent electrochemical characteristics, and can serve as one of the highly suitable electrode materials to be used in supercapacitors.

Evaluation of rGO decorated MnO2/NiO nanocomposite for high-performance photocatalytic and supercapacitor applications

To the degradation of dyes and for use as supercapacitors, MnO2/NiO@rGO (MNrGO) nanocomposite (NCs) were synthesized and characterized. X-ray Powder Diffraction (XRD) and Fourier-transform infrared spectroscopy (FT-IR) studies have been utilized to determine the crystalline structure and functional groups of the nanocomposites (NCs). In the photodegradation process, the Methylene blue (MB), Congo red (CR) and Methyl orange (MO) dyes had higher degradation efficiency, such as 98.5 % for MB within 35 min, 83.04 % for CR within 60 min, and 92.47 % for MO within 30 min, respectively. It showed a maximum capacitance value of 391.6 F/g at 0.5 A/g when its electrochemical characteristics were investigated in a 1 M KOH electrolyte solution. One of the main benefits of long-term applications is that the NCs retain 91 % of their electrochemical properties even after 5000 GCD cycles. These metal oxides are well-known as materials for environmental remediation due to their low cost, stability, efficiency, and low impact on the environment. Due to its better performance in both photocatalysis and electrocatalysis, MnO2/NiO@rGO nanohybrid has emerged as a promising long-term catalyst in these two areas.

Designing an asymmetric supercapacitor based on Co(OH)2@PANI nanocomposite synthesized via a facile hydrothermal method

The present study developed a Co(OH)2@PANI nanocomposite synthesized by a simple hydrothermal method as a novel electrode material for supercapacitor construction. The prepared nanocomposite is characterized through various techniques, including N2 adsorption/desorption isotherms, Fourier transform infrared spectroscopy, Raman spectroscopy, X-ray photoelectron spectroscopy, scanning electron microscopy, high-resolution transmission electron microscopy, energy-dispersive X-ray spectroscopy, and X-ray diffraction. The prepared supercapacitor was subjected to evaluate using cyclic voltammetry and galvanostatic charge/discharge tests in a 6.0 M KOH electrolyte solution. The incorporation of Co(OH)2 microneedle-like structures into polyaniline (PANI) has greatly enhanced the performance of the supercapacitor. In a three-electrode setup, the supercapacitor utilizing Co(OH)2@PANI nanocomposite electrode exhibits a high specific capacitance of 385 F g−1 at 1 A g−1. Even when the current density was increased to 10 A g−1, the capacitance retention remains at 67 %. In the asymmetric device, the capacitance retention was maintained at nearly 74.8 % after 5000 cycles. Additionally, the supercapacitor yields an optimum energy density and power density of 31.2 Wh kg−1 and 1050 W kg−1, respectively.

Reduced graphene oxide aerogel for supercapacitor electrode

In this study, the rGO aerogel material was successfully fabricated by freeze-drying combined with high-temperature reduction method. The characteristics of rGO aerogel were investigated by modern techniques such as SEM-EDX, XRD, Raman, N2 adsorption and desorption. Electrochemical properties were studied through cyclic potential scanning (CV), charge-discharge (GCD) and electrochemical Imdependance Spectroscopy (EIS) methods in 6M KOH electrolyte solution. Research results show that rGO aerogel has a large specific surface area and pore volume of 162.4 m2/g and 0.237 cm3/g, respectively, and a large specific capacitance of 90 F/g at a current density of 0.1. A/g and long charge-discharge life with specific capacitance reaching 87.5% after 500 charge-discharge cycles.

A stable and robust electrode using Copious metal oxide composite for green hydrogen production

AbstractThe exploration of inexpensive and copious materials for water splitting has not come to an end even though a lot of materials has been synthesised to cope with the high overpotential and Tafel slope. The present manuscript demonstrates fabrication and performance studies of Co3O4 and TiO2 composite (CTC) catalyst coated electrode for electrochemical water splitting. The use of CTC (Co3O4@TiO2) showed the band gap of 2.41 eV which is found to be suitable for efficient water splitting reaction. The electrode fabrication was done using CTL coated FTO glass that provided a stable cathodic electrode for overall water splitting. The detail electrochemical studies of CTC electrode were performed in 1 M KOH electrolyte solution in a three‐electrode system. The CTC exhibited lowest Tafel slope value for both hydrogen evolution reaction (HER) of 51 mV/dec and oxygen evolution reaction (OER) of 166 mV/dec, calculated at 10 mA/cm2. Moreover, the highest current density 66.59 mA/cm2 at 0.20 V and 85.84 mA/cm2 at 1.85 V was observed for HER and OER, respectively. The significantly low overpotential 104 mV for HER and 240 mV for OER at 10 mA/cm2 depicted the efficiency of catalyst. The chronoamperometry study showed no significant loss in the activity CTC coating upto 32 h. Thus, the CTC coated electrode is found to be an excellent, stable and robust electrocatalyst for economical green H2 production.

A facile synthesis of hierarchical porous carbon derived from renewable lignin for high-performance supercapacitor

In this work, we proposed a facile one-pot pyrolysis method to conveniently manufacture lignin-derived carbon materials with graded porous construction for use in supercapacitors. The renewable lignin was selected as precursor, while the potassium citrate was used as a pore-forming agent. The properties of the prepared lignin-derived carbon (LAC) and the performance for supercapacitor application were thoroughly evaluated. The LAC at optimal preparation conditions shows a layered porous structure with a large specific surface area of 3174 cm2 g−1 and pore volume of 2.796 cm3 g−1, where the specific capacitance reach to 241 F g−1 at 1 A g−1 scan rate in 6 M KOH electrolyte solution. At the same time, the specific capacitance remains at 220 F g−1 even at an excessive scan velocity of 20 A g−1, while the capacitance retention is still close to 91.3%. The capacitance retention rate is stable above 95% after 10,000 charge/discharge cycles, which shows the desired long-time stability. All these results demonstrate the outstanding properties of the new prepared LAC material and the considerable application potential in the field of electrical energy storage.

Structural and electrochemical properties of Cu doped NiCo2O4 prepared by microwave hydrothermal method

A series of NiCuxCo2-xO4 with x = 0, 0.02, 0.04, 0.06, 0.08 and 0.10 samples were synthesized using microwave hydrothermal method (MH). The structural, microstructural, and spectroscopic characterizations were carried out using X-ray diffraction (XRD), scanning electron microscopy (SEM) and X-ray photoelectron spectroscopy (XPS). All the samples are in Cubic phase with space group Fd3m. The samples x ≥ 0.08 shows some impurity phases. The average grain size for all the samples is in the range of 30–55 nm. The specific capacitance (Csp) 250.66 Fg−1, energy density (E) 22.22 Whkg−1 and power density (P) 757.80 Wkg−1 was observed for x = 0.06 with a mass loading of 7 mgcm−2 and in 2 M aqueous KOH electrolyte solution at a current density of 1 Ag−1. Therefore, the Cu doping with x = 0.06 shows good redox activities and hence can be used in electric batteries and supercapacitors.

Dark Current Water Splitting Employing Ni3TeO6 as a Photocharged Photoelectrocatalyst

Herein, the photoelectrocatalytic and photocharging activity of a Ni3TeO6 (NTO‐700) photoelectrocatalyst for water oxidation in alkaline medium is demonstrated and calcined at 700 °C. The photoelectrocatalytic (PEC) activity of the sample is increased upon an increase in the illumination time. With a twofold increase in photocurrent density at 1.8 V, the PEC 150 sample (having been illuminated for 150 min) attained the highest PEC activity. The synthesized material has displayed an excellent charge storage capacity in KOH and Na2SO4 electrolyte solutions (both 0.1 m). The chrono‐amperometry measurement, subsequent to light interruption, has sustained almost 44% higher current density (even after 200 min) compared to the pure electrocatalytic baseline in a Na2SO4 electrolyte. The charge transfer resistance, Rct, decreases from 633.40 to 170.40 Ω, while the charge transfer rate constant, kct, increases from 7.93 to 27.03 s−1, as a function of illumination time. This points to fast separation of electron–hole (e−–h+) pairs and a slower recombination rate. The lower values of the charge transfer resistance and the time constant recorded for the light interrupted samples, as compared to the electrochemical sample, are attributed to the stored charge that drives water oxidation at a higher rate.

Facile hydrothermal synthesized MoV2O8/MoO3 microclusters-based electrode materials for high-capacity asymmetric supercapacitors

Engineering novel transition metal oxide materials with micro/nanostructures has endowed unusual electrochemical properties. Herein, we reported the MoV2O8/MoO3 microclusters (MVO/MO MCs) synthesized by a simple and facile hydrothermal process. Furthermore, the MVO/MO MC-based electroactive materials were studied at various annealing temperatures of 300, 400, and 500 °C. The prepared materials wrere characterized via different analysis methods for the investigation of phase, morphology, surface area, and oxidation states. The optimized MVO/MO MC electrode revealed a superior specific capacity of 392.58 mAh g−1 at 1 A g−1 (2844 F g−1) in a 1 M KOH electrolyte solution. The MVO/MO MC electrode also exhibited excellent capacity retention of 101% with a corresponding coulombic efficiency of 99%. Accordingly, the fabricated pouch-like asymmetric supercapacitor (ASC) with the MVO/MO MCs and activated carbon materials delivered maximum power and energy densities of 2306.95 W Kg−1 and 37.06 Wh kg−1, respectively. Additionally, the ASC showed superior capacity retention of 128% with 97% of coulombic efficiency. Also, the ASC devices were employed to test the practical application by powering electronic gadgets.

Nitrogen implanted carbon nanosheets derived from Acorus calamus as an efficient electrode for the supercapacitor application

Modern society's biggest challenges are affordable, clean energy production and storage. Thus, recent research aims at the discovery of novel electrode materials for enhanced energy production and storage. Herein, nitrogen-implanted carbon particles were synthesized for the first time from the Acorus Calamus for the symmetric supercapacitor application. The KOH-activated carbon particles at 750 °C (C-750) under a nitrogen atmosphere revealed the better structural, textural, morphological, and electrochemical performance. The BET analysis confirmed that the C-750 carbon nanoparticles tremendously enhanced the surface area of about 3551.07 m2/g. Further, the pore size and pore volume were obtained from BJH analysis that showed 3.70 nm and 0.51 cc/g, respectively. The high surface area along with the mesoporous nature of the C-750 sample effectively enhanced the specific capacitance to 354.44 Fg−1 at 1 Ag−1 using a 6 M KOH electrolytic solution. Further, the enhancement of energy and power density of the C-750 was observed at about 47.2 Whkg−1 and 16,000 Wkg−1, respectively.

Ag doped Co3O4 nanoparticles for high-performance supercapacitor application

Ag doped Co3O4 nanoparticles (NPs) were synthesized via a co-precipitation method changing the concentration of Ag. The crystal structure, morphology, surface area, functional group, optical band gap, and thermal property were investigated by XRD, SEM, BET, FTIR, UV–Vis, and TGA/DTA techniques. The XRD results showed the formation of single-cubic Co3O4 nanostructured materials with an average crystal size of 19.37 nm and 12.98 nm for pristine Co3O4 and 0.25 M Ag-doped Co3O4 NPs. Morphological studies showed that pristine Co3O4 and 0.25 M Ag-doped Co3O4 NPs having a porous structure with small spherical grains, porous structures with sponge-like structures, and loosely packed porous structures, respectively. The pristine and 0.25 M Ag-doped Co3O4 NPs showed BET surface areas of 53.06 m2/g, and 407.33 m2/g, respectively. The band gap energy of Co3O4 NPs were 2.96 eV, with additional sub-bandgap energy of 1.95 eV. Additionally, it was discovered that the band gap energies of 0.25 M Ag-doped Co3O4 NPs ranged from 2.2 to 2.75 eV, with an extra sub-band with energies ranging from 1.43 to 1.94 eV for all as-prepared samples. The Ag-doped Co3O4 as prepared samples show improved thermal properties due to the doping effect of silver. The CV test confirmed that the 0.25 M Ag-doped Co3O4 NPs exhibited the highest specific capacitance value of 992.7 F/g at 5 mV/s in a 0.1 M KOH electrolyte solution. The energy density and power density of 0.25 M Ag-doped Co3O4 NPs were 27.9 W h/kg and 3816.1 W/kg, respectively.

Studies of the effect of Hf doping on the electrochemical performance of C15 Laves type metal hydride battery anode alloys

This paper focuses on the studies of the electrochemical performance of arc-melted Hf-modified Ti-Zr based AB2 Laves type metal hydride battery anode alloys with composition HfxZr24-xTi6.5V3.9Mn22.2Fe3.8Ni38La0.3Sn0.3 (x = 1–4). The phase composition and the morphology of the alloys were characterized by X-ray Diffraction (XRD) and Scanning Electron Microscopy (SEM). Metal-gas interactions and electrochemical performances were studied by building PCT diagrams and by electrochemical tests performed in a 9 N KOH electrolyte solution at ambient temperature when using the half-cells in a three-electrode assembly.All studied alloys were two-phase and contained the Laves phase intermetallics of C15 (major constituent) and C14 (minor constituent) types. An increase in Hf content caused a growth of the abundance of the C14 phase and was accompanied by a decrease in the electrochemical discharge capacities, exchange current densities, and H diffusion rates as compared to the Hf-free alloy. Among the Hf-containing alloys, an introduction of 2 wt% Hf into the alloy's composition resulted in a higher H diffusion rate, while the highest H storage capacity has been reached for the alloy with the lowest, 1 wt%, content of Hf. The surface of the alloys contained catalysing hydrogen exchange metallic nickel clusters with the highest enrichment observed for the 2 wt% Hf alloy. An influence of Hf on the hydrogen storage and electrochemical performance can be understood in terms of the modification of the intrinsic properties of the alloys following a substitution (Zr/Ti) → Hf as C15 type alloys show the fastest hydrogen diffusion rates while a gradually increasing content of the hexagonal C14 type in the Hf-containing alloys slows down the H diffusion process.

Cost-effective preparation of ZnO-CNT nanocomposite-based electrode for supercapacitor application

The increasing energy demand has attracted researchers to develop a cost-effective electrode material for energy storage applications. Zinc Oxide (ZnO) and Carbon nanotubes (CNT) are among the most explored electrode materials for such applications. However, the reported literature doesn’t have a cost-effective approach. The present work has reported the cost-effective synthesis of ZnO and ZnO-CNT nanocomposite via hydrothermal and simple blending methods respectively. The structural and morphological properties were studied using XRD and FESEM. It was found that the diameter of CNT was ∼ 22 nm and the ZnO nanoparticles were spherical in shape, having an average particle size of ∼ 13 nm. Further, graphite rod was used as electrode substrate, which was optimized to study the electrochemical behavior of active materials in 6 M KOH electrolytic solution. The CV and GCD studies revealed that with the decrease in scan rate/current density, the value of specific capacitance increased. The maximum value of specific capacitance achieved was 67.5F/g at 1 A/g current density. In addition, the ZnO-CNT nanocomposite electrode showed cyclic stability up to 16,000 cycles. From EIS spectra, it has been found that the ZnO-CNT nanocomposite had a low bulk resistance (Rs) value i.e., 2.6 Ω. Thus, the electrochemical performance of ZnO-CNT nanocomposite inferred its high potential for future energy storage applications.

Preparation and Photoelectric Properties of C-LaFeO3 Composites

The C spheres synthesized by a hydrothermal method were used as a C source, which was doped with LaFeO3 to obtain C-LaFeO3 composites with different C contents (5%, 10%, 15%, and 20%). The effects of C content on the structure, morphology, and photoelectric properties of LaFeO3 were investigated experimentally. The results show that C doping does not change the crystal structure of LaFeO3. The proper amount of C doping improves the photocatalytic and electrochemical activities of the composites. However, excessive C reduces the photocatalytic and electrochemical activities of the C-LaFeO3 composites. Comparing the different C contents, when the C content is 15%, the photocatalytic performance of C-LaFeO3 photodegrading methylene blue solution (MB) under visible light is the best, reaching an efficiency of 97%. In addition, electrochemical tests in a 6 M KOH electrolyte solution demonstrate that C doping significantly improves the redox reaction capacity, and the specific capacitance of 15% C-LaFeO3 (466.08) F/g) at a current density of 0.5 A/g is about 2.5 times that of LaFeO3 (180.10 F/g). Furthermore, EIS studies show that that the ion diffusion resistance of the 15% C-LaFeO3 electrode decreased, which is indicative of good electrochemical performance.

Electrochemical Investigation of the OER Activity for Nickel Phosphite-Based Compositions and Its Morphology-Dependent Fluorescence Properties

Herein, we present the investigation of catalytical and fluorescence properties for Ni11(HPO3)8(OH)6 materials obtained through a hydrothermal approach. As part of the constant search for new materials that are both cost effective and electrocatalytically active for the oxygen evolution reaction (OER) in alkaline medium, the present study involves several graphite electrodes modified with Ni11(HPO3)8(OH)6 mixed with reduced graphene oxide (rGO) and carbon black. The experimental results obtained in 0.1 mol L–1 KOH electrolyte solution show the electrode modified with rGO, 5 mg carbon black and 1 mg nickel phosphite as displaying the highest current density. This performance can be attributed to the synergistic effect between nickel phosphite and the carbon materials. Investigation of the electrode’s OER performance in 0.1 mol L–1 KOH solution revealed a Tafel slope value of just 46 mV dec–1. By increasing the concentration to 0.5 and 1 mol L–1, this value increased as well, but there was a significant decrease in overpotential. Fluorescence properties were analyzed for the first time at the excitation length of 344 nm, and the observed strong and multiple emissions are described.

Self-promoted Nickel-chalcogenide Nanostructures: A Novel Electrochemical Supercapacitor Device-design Strategy

Self-grown nickel-chalcogenides viz ., sulphide (NiS), selenide (NiSe), and sulfoselenide (NiSSe) nanostructures of the aligned nanorod, nanosheet, and nanobud-type morphologies are successfully synthesized through one-pot hydrothermal synthesis route on 3-D nickel-foam (NiF). The precursors of sulfur and selenium break down into S 2− and Se 2− ions, which then react with oxidized Ni 2+ ions on the surface of pure NiF to make NiS, NiSe, and NiSSe superstructures. The structural, morphological, and chemical states of as-grown Ni-based electrodes are monitored through various measurement tools. The as-obtained Ni-based NiS, NiSe and NiSSe electrode materials of various morphologies endow specific capacitances and specific capacities, at a current density of 3 A g −1 , of 1683.5 F g −1 , 1563.6 F g −1 , and 3314.9 Fg −1 and 187.05, 173.86, and 368.32 mAh g −1 respectively, in a three-electrode system containing 1.0 M KOH electrolyte solution. The NiSSe demonstrating the highest specific capacitance and outstanding chemical stability compared to other electrode materials might be due to the synergistic effect to improve overall electrochemical activity. In addition, the NiSSe electrode is chemically stable and mechanically robust as it doesn't detach from the conductive NiF substrate even at a high current density. Consequently, the as-designed NiSSe//NiSSe symmetric supercapacitor assembly divulges1658.6 Wkg −1 power density and 19.21 Whkg −1 energy density with the cycling stability of 93.48%. Connecting two cells in a series a panel “CNED” composed of nearly forty-two LEDs is ignited with high light intensity, adducing the practical importance of mixed metal chalcogenide electrode material in the energy storage sector.

NiFe Layered Double Hydroxide Electrocatalyst Prepared via an Electrochemical Deposition Method for the Oxygen Evolution Reaction

Herein, we aimed to obtain NiFe layered double hydroxide (LDH) with a controlled phase and surface morphology as a highly active and stable oxygen evolution catalyst via the electrochemical deposition method, which was thermodynamically stable for the oxygen evolution reaction (OER) in an alkaline medium. The NiFe-LDH sample was analyzed by sophisticated instruments and tested as an electrocatalyst on Toray carbon (TC). The NiFe-LDH electrocatalyst showed an excellent performance with lower overpotential of 0.27 V at 35 mA cm−2 and higher density of 125 mA cm−2 for OER in the 1 M KOH electrolyte solution. Moreover, the prepared catalyst exhibited unpredictable long-time stability for 700 h. From our knowledge, NiFe-LDH is a robust highly stable electrocatalyst compared to the recent reports.

Microwave assisted synthesis of Mn3O4 nanograins intercalated into reduced graphene oxide layers as cathode material for alternative clean power generation energy device

Mn3O4 nanograins incorporated into reduced graphene oxide as a nanocomposite electrocatalyst have been synthesized via one-step, facile, and single-pot microwave-assisted hydrothermal technique. The nanocomposites were employed as cathode material of fuel cells for oxygen reduction reaction (ORR). The synthesized product was thoroughly studied by using important characterization, such as XRD for the structure analysis and FESEM and TEM analyses to assess the morphological structures of the material. Raman spectra were employed to study the GO, rGO bands and formation of Mn3O4@rGO nanocomposite. FTIR and UV–Vis spectroscopic analysis were used to verify the effective synthesis of the desired electrocatalyst. The Mn3O4@rGO-10% nanocomposite with 10 wt% of graphene oxide was used to alter the shiny surface of the working electrode and applied for ORR in O2 purged 0.5 M KOH electrolyte solution. The Mn3O4@rGO-10% nanocomposite electrocatalyst exhibited outstanding performance with an improved current of − 0.738 mA/cm2 and shifted overpotential values of − 0.345 V when compared to other controlled electrodes, including the conventionally used Pt/C catalyst generally used for ORR activity. The tolerance of Mn3O4@rGO-10% nanocomposite was tested by injecting a higher concentration of methanol, i.e., 0.5 M, and found unsusceptible by methanol crossover. The stability test of the synthesized electrocatalyst after 3000 s was also considered, and it demonstrated excellent current retention of 98% compared to commercially available Pt/C electrocatalyst. The synthesized nanocomposite material could be regarded as an effective and Pt-free electrocatalyst for practical ORR that meets the requirement of low cost, facile fabrication, and adequate stability.