Oxide Nanocomposite Materials Research Articles

Facile sonication synthesis of MnAl2O4/ZnO nanocomposite as an advanced electrode material for supercapacitor applications

Present studies on maintaining, effective energy providers and storage systems have developed because of problems with energy limitations, fossil fuel depletion and pollution. Spinel oxide nanocomposite electrode material is a superior remedy for supercapacitors (SCs). Herein, we synthesized MnAl2O4 and MnAl2O4/ZnO nanocomposites using the sonication method for energy storage devices. The manufactured material’s morphology, interfacial area and structural features were determined using scanning electron microscopy (SEM), Brunauer Teller Emmett analyses (BET) and X-ray diffraction (XRD), respectively. The crystalline nature of MnAl2O4 and MnAl2O4/ZnO nanosheets was observed by the XRD analysis. The electrochemical performance of the manufactured material was determined utilizing nickel foam (NF) as a conductive surface and 2.0 M KOH electrolyte, galvanostatic charging-discharging (GCD), electrochemical impedance spectroscopy (EIS) and cyclic voltammetry (CV) study. Electrochemical outcomes showed that MnAl2O4/ZnO nanocomposite exhibits specific capacitance (Cs) of 1490.07 F/g at 1.0 A/g with high cyclic stability over 5000th cycles. Furthermore, an energy and power density of 55.96 Wh/kg and 260 W/Kg, correspondingly, were exhibited by MnAl2O4/ZnO nanocomposite pseudocapacitors. Compared to MnAl2O4 (0.47 Ω) the charge transfer resistance (Rct) value for MnAl2O4/ZnO (0.12 Ω) was smaller calculated via Nyquist plot and exhibited steady behaviour for 50 h. The outstanding potential of the electrode material MnAl2O4/ZnO was highlighted in this work, along with a novel method for producing multi-element composite materials at a reasonable cost and with excellent performance that could find use in a variety of supercapacitor and upcoming energy storage applications.

Uricase conjugated nanostructured NiFe2O4/rGO modified flexible screen-printed carbon electrode based interface for long-range electrochemical determination of uric acid

Uric acid (UA) is a biomarker linked with gout and kidney stones that is harmful to the human body. Thus, this study explores the detection of UA using the differential pulse voltammetry (DPV) method. Initially synthesizing a highly active Nickel ferrite/reduced graphene oxide (NiFe2O4/rGO) nanocomposite ferrite material by simple surfactant-free low-temperature hydrothermal approach. The as-synthesized material was studied using various spectroscopic and microscopic techniques. The bioelectrode was fabricated on a screen-printed carbon electrode (SPCE), and the as-prepared Uricase/NiFe2O4/rGO/SPCE demonstrated improved electrochemical oxidation peak current (Ipa). While its electrochemical biosensing performance towards various UA concentrations shows a wide linear range from 5 to 900 μM, with a lower limit of detection (21·9 μM), high sensitivity (1·05×10−4 mA/μM cm2), good selectivity (RSD < 5·7 %), excellent stability, and repeatability. In addition, the fabricated bioelectrode was also explored to quantify the amount of UA in bovine serum albumin (BSA) real spiked samples. Hence, the proposed biosensor has potential applications in point-of-care-treatment of numerous disorders related to UA metabolism.

Fabrication of CuO derived reduced graphene oxide photocatalyst for the strategic decolorization of Congo red from an aqueous environment

Herein, we designed a novel reduced graphene oxide functionalized copper oxide (rGO-CuO) nanocomposite material through simple method. The synthesized rGO-CuO nanocomposite is rigorously characterized via advanced techniques including X-ray diffraction (XRD), scanning electron microscopy (SEM), and energy-dispersive X-ray spectroscopy (EDX). These characterizations reveal crucial insights into the nanocomposite crystalline attributes, phase purity, morphological characteristics, and elemental composition, collectively confirming its successful fabrication. Furthermore, the synthesized nanocomposite is subsequently used for the proficient decolorization of Congo Red (CR) dye within an aqueous medium employing a careful optimization of experimental variables including the concentration of sodium borohydride (NaBH4), solar irradiation, and catalytic dosage. The developed photocatalytic achieved 98.7 % degradation of CR dye at a minimal catalyst dosage of 2.4 mg in a 5-min reaction time. Notably, the nanocomposite exhibits reusability for up to five cycles with 88 % efficiency, underscoring the durability and reliability of the rGO-CuO photocatalyst. Moreover, the kinetic study evaluation demonstrated that the decolorization of dye at surface of the catalyst follows pseudo first order reaction. The rGO-CuO nanocomposite could be a suitable candidate for the rapid photocatalytic degradation of CR dye not only at low level but also at industrial scale.

Recent Progress in Marine Antifouling Technology Based on Graphene and Graphene Oxide Nanocomposite Materials

Sea vessels and artificial sea‐based structures are severely affected by biofouling, i.e., the formation of deposits of living and dead marine organisms that belong to different species and range in size from unicellular bacteria to multicellular seaweed and mussels. This is a significant engineering problem since they essentially alter the geometry of the hull, increasing friction and reducing the speed of vessels, thus increasing the cost and environmental footprint of transportation. Given the scale of global transportation reaches several billion tons per year, the socioeconomic consequences of the reduction in transit speed and increased consumption of fuel continue to drive researchers and engineers to develop strategies to combat the processes of marine biofouling. Many types of antifouling paints, coatings, and materials that have been designed and tested, and in some instances used commercially, suffer from shortcomings ranging from environmental toxicity to limited efficiency and durability. In this review article, a brief overview of the traditional antifouling materials is presented and recent achievements in the design of advanced antifouling materials based on such nanomaterials as graphene, nanotubes, nanoparticles, and more complex nanostructures are discussed. These materials exhibit excellent antifouling properties and candrive a breakthrough in how marine biofouling is tackled.

High-efficiency recyclable reduced graphene oxide-tin oxide nanocomposite catalyst for esterification

Graphene oxide (GO) possesses 2D nanostructures and was synthesized indigenously via the enhanced Hummer method. It is well-accepted that the redox approach is a distinctive technique to fabricate GO on an expanded scale. Here, reduced graphene oxide-tin oxide (SnO2-rGO) nanocomposite material was produced for application as an efficient heterogeneous solid acid catalyst esterification reaction. Fourier transform infrared analysis was carried out to validate the incidence of oxygen functional groups in GO and SnO2-rGO nanocomposite. The Raman spectra of GO and SnO2-rGO nanocomposite have been simulated to get stable structure and functional groups. To get surface morphological and structural features, powder X-ray diffraction, scanning electron microscope-energy dispersive X-ray spectra, transmission electron microscope and high resolution-TEM analysis, and thermogravimetric analysis were delineated during this experimental study. It is seen that the catalyst has high efficiency for esterification reaction. The maximum efficiency (96% yield) was obtained when a 1:3 (acetic acid to benzyl alcohol) molar ratio, catalyst (25 mg), temperature (60 0C), and time (4 h) were maintained. The SnO2-rGO nanocomposite was recycled several times with a minimal loss of its efficiency.

Synergetic vanadium oxide nanocomposite cathode material with high specific capacity and long life for advanced aqueous zinc-ion batteries

Based on their high safety, low cost, and environmental friendliness aqueous zinc-ion batteries (AZIBs) are considered one of the most attractive candidates for large-scale energy storage applications. Vanadium-based compounds with high theoretical specific capacity are promising cathode materials for AZIBs. However, it is a great challenge for modified vanadium oxygen compounds to gain excellent zinc storage performance due to the strong electrostatic interaction between Zn2+ and V, O. Here, we present a one-step hydrothermal method and subsequent calcination to gain an advanced V2O5/VO2 nanocomposite as the cathode of highly stable AZIBs. The obtained composite has a synergistic effect, and the introduction of VO2 enhances the composites' general characteristics. Therefore, this composite structure not only accelerates the intercalation dynamics of Zn2+, but also further consolidates the stability during cycling. As a result, the as-synthesized cathode provides a high specific capacity of 453.2 mA h g−1 at 1 A g−1 and excellent cycle stability, with a high capacity maintained (200 mA h g−1) over 80 % after 2000 cycles at 10 A g−1. This work provides a new perspective for the development of viable insertion materials for AZIBs.

In-Situ Grown NiMn2O4/GO Nanocomposite Material on Nickel Foam Surface by Microwave-Assisted Hydrothermal Method and Used as Supercapacitor Electrode.

The NiMn2O4/graphene oxide (GO) nanocomposite material was in situ grown on the surface of a nickel foam 3D skeleton by combining the solvent method with the microwave-assisted hydrothermal method and annealing; then, its performance was investigated as a superior supercapacitor electrode material. When nickel foam was soaked in GO aqueous or treated in nickel ion and manganese ion solution by the microwave-assisted hydrothermal method and annealing, gauze GO film or flower-spherical NiMn2O4 was formed on the nickel foam surface. If the two processes were combined in a different order, the final products on the nickel surface had a remarkably different morphology and phase structure. When GO film was first formed, the final products on the nickel surface were the composite of NiO and Mn3O4, while NiMn2O4/GO nanocomposite material can be obtained if NiMn2O4 was first formed (immersed in 2.5 mg/L GO solution). In a 6M KOH solution, the specific capacitance of the latter reached 700 F/g at 1 A/g which was superior to that of the former (only 35 F/g). However, the latter's specific capacitance was still inferior to that of in-situ grown NiMn2O4 on nickel foam (802 F/g). Though the gauze-formed GO film, almost covering the preformed flower-spherical NiMn2O4, can also contribute a certain specific capacitance, it also restricted the electrolyte diffusion and contact with NiMn2O4, accounting for the performance decrease of the NiMn2O4/GO nanocomposite. A convenient method was raised to fabricate the nanocomposite of carbon and double metal oxides.

Facile synthesis of dysprosium oxide/bismuth oxide nanocomposite electrode materials with good electrocatalytic performance

Background: Benzoic acid is widely applied in the food field, including beverages as the antimicrobial preservative due to its strong inhabitation role to bacteria and yeasts. However, excessive intake of benzoic acid can easily cause abdominal pain and diarrhea and can even result in metabolic diseases. Hence, it is important to seek simple, accurate and sensitive strategies to detect low-trace benzoic acid. Objective: The aim of this study is to synthesize dysprosium oxide/bismuth oxide nanocomposites using dysprosium sulphate and sodium bismuthate as the raw materials and research the electrochemical sensing properties for the detection of benzoic acid. Methods: Dysprosium oxide/bismuth oxide nanocomposites were synthesized by a facile hydrothermal route. The dysprosium oxide/bismuth oxide nanocomposites were characterized by X-ray diffraction, electron microscopy, X-ray photoelectron spectroscopy and electrochemical impedance spectroscopy. Results: The dysprosium oxide/bismuth oxide nanocomposites are composed of nearly circular-shaped particles with polycrystalline cubic Dy2O3 and triclinic Bi2O3 phases. The size of the nearly circular-shaped particles is about 50 to 200 nm. The electrons are easier to transfer by the dysprosium oxide/bismuth oxide nanocomposite-modified electrode than the bare electrode. A pair of quasi-reversible cyclic voltammetry (CV) peaks located at -0.155 V and -0.582 V exist in the CV curve of 0.1 M KCl buffer solution containing 2 mM benzoic acid. The nanocomposite-modified electrode shows a linear detection range and detection limit of 0.001-2 mM and 0.18 μM, respectively, for benzoic acid detection. Conclusion: The dysprosium oxide/bismuth oxide nanocomposite-modified electrode reveals superior electro-catalytic activity towards benzoic acid.

Hierarchical graphene oxide-Ni3S2 quantum dots nanocomposites modified glassy carbon electrode for electrochemical detection of dopamine and tyrosine

A facile synthetic strategy is demonstrated to generate nickel sulfide quantum dots (Ni3S2). The thus formed Ni3S2 quantum dots are assembled onto exfoliated graphene oxide sheets hydrothermally to form nickel sulfide-graphene oxide nanocomposite material (GO-Ni3S2). The microscopic and spectroscopic characterization of the GO-Ni3S2 nanocomposites revealed the shape, size, crystalline phases, and oxidation states (of elements) of the hybrid material. The GO-Ni3S2 nanocomposites are then coated onto the glassy carbon electrode by drop casting to form GO-Ni3S2@GCE. The modified electrode is then used to detect dopamine and tyrosine simultaneously. The effect of scan rate, analyte concentrations, pH, and interfering agents on the peak current are studied to establish a plausible mechanism for oxidizing dopamine and tyrosine at GO-Ni3S2@GCE. The GO-Ni3S2@GCE is stable for 3 weeks and ten cycles of washing with minimal loss in the peak current in each cycle. Dopamine with a concentration as low as 12 nM can be detected using the GO-Ni3S2@GCE system.

Synthesis and characterization of bio-nanocomposites: Functionalization of graphene oxide with a biocompatible amino acid

Graphene oxide (GO) is a complicated composite which can be synthesized from graphite or other carbon sources by a simple top-down method. Graphene is a two-dimensional carbon sheets which can be oxidized to synthesis its oxide structure. The graphene oxide sheets can be functionalized in order to be used actively in different areas. The graphene oxide nanocomposite materials have attracted researches and scientists’ attention due to their wade applications from electrochemical industry to drug delivery. In this novel work the authors have synthesized graphene oxide films and then functionalized with an amino acid, Lysine, and Cu in order to synthesize the Lysine-Cu-Graphene oxide combination. The novelty of this investigation is the authors have functionalized graphene oxide with l-lysine as an amino acid at diverse temperature. Also, this product is environmentally friendly product since it is soluble in aqueous medium and can be applied as an active antibacterial material. After the synthesizing process, the obtained materials had been characterized using different techniques such as Fourier-transform infrared spectroscopy (FTIR) to confirm the success of the functional reaction. Ultra violet visible (UV–Vis) spectroscopy, atomic force microscopy (AFM), X-ray diffraction (XRD), and thermal gravimetric (TG) analysis, were also utilized to approve the covalent attachment of Lysine and also to show the improvement in the thermal stability of GO.

Application of Synthesized Biomass Bamboo Charcoal–Iron Oxide “BC/Fe” Nanocomposite Adsorbents in the Removal of Cationic Methylene Blue Dye Contaminants from Wastewater by Adsorption

In this work, synthesized, raw-bamboo-biomass-based magnetic “BC/Fe” bamboo charcoal–iron oxide nanocomposite adsorbents were characterized and tested for their effects on the removal of aqueous-phase cationic methylene blue (MB) dye pollutants from synthetic wastewater through a laboratory batch adsorption study. This batch adsorption study aimed to identify various physico-chemical process parameters such as initial dye concentration, solution pH, adsorbent dose, temperature, and their effects on the adsorption kinetics and adsorption isotherm characteristics. From the kinetic studies, it was found that the amount of MB dye adsorption by synthesized adsorbents qe (mg/g) increased from 9.50 mg/g to 15.30 mg/g with the increase in the initial dye concentration range of 10 to 30 ppm, as per contact time, but decreased with the increase in the temperature range from 30 to 60 °C and the adsorbent doses from 20 to 40 mg, respectively, under specified experimental process conditions. From the kinetic study, it was also found that equilibrium was reached within 120 min, the adsorption kinetics followed three mechanistic steps, and the pseudo-second-order (PSO) kinetic model was applicable to explain the data of the batch adsorption kinetics. The various kinetic model parameters were determined from a fitted model equation. Furthermore, there was an increase in the amount of the MB dye adsorption qe (mg/g) from 9.87 mg/g to 17.62 mg/g with the increase in the solution pH from 3 to 7, and a reduction in the amount of dye adsorption qe (mg/g) was found at the solution pH of 10 for a 20 ppm MB dye solution at 30 °C. Both the Freundlich and Langmuir isotherm models were applicable to the equilibrium data, and the maximum adsorption capacity from the Langmuir isotherm fitting was 111.11 mg/g, which was comparative to or even better than many other magnetic adsorbents for methylene blue dye adsorption. Finally, the regeneration and reusability of the magnetic “BC/Fe” bamboo charcoal–iron oxide nanocomposite materials as well as the limitations of these batch adsorption studies are also discussed here.

Silver/reduced graphene oxide nanocomposite materials synthesized via a green molecular level mixing

The fabrication of nano reinforced metal matrix composites (MMCs) is scientifically essential to further upgrade the thermal, electrical, and mechanical properties of current MMCs. Here, we present a green molecular mixing (MLM) of silver (Ag) and graphene (G) to overcome these challenges. Experimental results show that the green MLM allows to homogeneously mix 3 vol. % of G as observed with traditional MLM while adding a control on the oxidation steps. Metal and GO reductions can be precisely control by varying the solution temperature. Highly thermal conductivity and strong elastic modulus nanocomposites are fabricated making it an eco-friendlier mixing process.

Insights in Utilizing NiCo2O4/Co3O4 Nanowires as Anode Material in Lithium‐Ion Batteries

AbstractIn this study, a facile and cost‐effective hydrothermal approach is employed to synthesize a mesoporous NiCo2O4/Co3O4 nanocomposite with nanowire morphology by using polyvinyl pyrrolidone as structure‐directing agent. The obtained NiCo2O4/Co3O4 nanocomposite shows better electrochemical performance than pure NiCo2O4 due to mainly two reasons: i) a strong synergistic effect between NiCo2O4 and Co3O4, which enhances the Li+ diffusion rate as well as lower the charge‐transfer resistance, and ii) the involvement of Co3O4 to contribute to the total capacity due to its high electrochemical activity. However, the performance of a NiCo2O4/Co3O4 nanocomposite electrode starts degrading after 400 cycles while pure NiCo2O4 maintains steady performance. Since the NiCo2O4/Co3O4 nanocomposite sample shows high porosity, it is believed that the obtained nanowire morphology cannot tolerate volume variations, which are generally triggered off during repeated Li+ (de‐)insertion at long‐term cycling. Therefore, the obtained results bring new insights in terms that there is a sweet spot between Li+ diffusion and high porosity in utilizing Co3O4 within a nanocomposite. This study is of guidance to shed the light on the research of ternary transition metal oxide nanocomposite materials for lithium‐ion batteries.

Synthesis, Characterization and Scintillation Response of ZnWO4-GO Nanocomposite

Graphene-based oxide nanocomposite materials have been commonly used in various applications due to their novel features. In this study, zinc tungstate /graphene-oxide composite nanoparticles (ZnWO4/GO CNPs) were synthesized by a simple chemical method and their structural and optical properties were investigated. Results from EDX verified the presence of associated elements in the structure. The morphology, particle size and structural parameters were also studied and reported. The prepared composite was in monoclinic wolframite crystalline phase with spherical uniformly morphology and average particle size of 299 nm. Under UV and alpha ray irradiation, the prepared ZnWO4/GO CNPs showed blue-green emissions and strong scintillation sensitivity respectively at room temperature. The results showed that ZnWO4/GO CNPs can be a suitable candidate for a wide range of applications in optoelectronic devices.

Kinetics and adsorption isotherm model of 2-thiouracil adsorbed onto the surface of reduced graphene oxide-copper oxide nanocomposite material

Graphene-construct nanocomposite materials have gathered considerable scientific importance for their unique ability to detect and remove various bioactive molecules/pollutants. Herein, we report on rGO-CuO nanocomposite as an adsorbent material for removing thiouracil biomolecules, viz-6A2TU and 6A5N2TU, respectively. The synthesized rGO-CuO nanocomposite is characterized using UV-vis, FTIR, XRD, SEM-EDX, Raman, and TEM analysis. The surface morphology of rGO-CuO shows well exfoliation with rGO wrapped on the surface of Cu and CuO nanoparticles. While the FTIR, X-ray diffraction, and UV-vis spectroscopic analysis show successful adsorption of 6A2TU and 6A5N2TU on the outer surface of rGO-CuO. rGO-CuO selectively adsorb the uracil derivatives with good efficiency compared to individual components. The binding kinetics of 6A2TU & 6A5N2TU on rGO-CuO are studied using UV-vis spectroscopy. The order of the reaction; pseudo 2nd order kinetics suites well with correlation coefficient (R2– 0.9999), representing proper surface-oriented chemisorption via coordination mechanism. The rGO-CuO shows excellent adsorption behavior with a maximum removal efficiency of 78.36% and 84.56% for 6A2TU and 6A5N2TU, respectively, and following the Temkin adsorption isotherm model. These characteristic features of the material provide the huge removal capacity of the thiouracil derivatives and reusability up to 92%. This nanocomposite material can remove antibiotics/bioactive molecules (organic pollutants) in the aquatic environment.

Recent Advances and Perspectives of Nanotechnology in Anaerobic Digestion: A New Paradigm towards Sludge Biodegradability

Anaerobic digestion (AD) is the strategy of producing environmentally sustainable bioenergy from waste-activated sludge (WAS), but its efficiency was hindered by low biodegradability. Hence, the usage of nanomaterials was found to be essential in enhancing the degradability of sludge due to its nanostructure with specific physiochemical properties. The application of nanomaterials in sludge digestion was thoroughly reviewed. This review focused on the impact of nanomaterials such as metallic nanoparticles, metal oxide nanoparticles, carbon-based nanomaterials, and nanocomposite materials in AD enhancement, along with the pros and cons. Most of the studies detailed that the addition of an adequate dosage of nanomaterial has a good effect on microbial activity. The environmental and economic impact of the AD enhancement process is also detailed, but there are still many existing challenges when it comes to designing an efficient, cost-effective AD digester. Hence, proper investigation is highly necessary to assess the potency of utilizing the nanomaterials in enhancing AD under various conditions.

Novel functionalized magnetic graphene oxide nanocomposite material for efficient vanadium(V) capturing from tea samples

Novel functionalized magnetic graphene oxide nanocomposite material for efficient vanadium(V) capturing from tea samples

Regeneration study of MB in recycling runs over nickel vanadium oxide by solvent extraction for photocatalytic performance for wastewater treatments

Recently, researchers are concentrating on the synthesis of composite materials to enhance the efficiency of the materials in various applications. In this work, nickel vanadium oxide (NiV2O6) nanocomposite material is prepared via two methods and the prepared samples have been characterized with basic studies to analyse the effect of preparation method and the reaction time. The XRD studies reveal a polycrystalline growth in both the methods. The broad XRD peaks obtained for samples prepared via hydrothermal method suggests the size reduction and 1D nanostructure formation. The SEM analysis shows the formation of 1D structures in hydrothermal and 3D microsphere structures in solvothermal methods. The possible formation mechanism behind this formation has been discussed in this manuscript. The FTIR peaks in the fingerprint region confirm the formation and vibration of metal-oxygen bonds. The large optical bandgap values obtained from Tauc plot again confirms the formation of nanostructures of the synthesized samples. The photocatalytic activity of nickel vanadium oxide on methylene blue dye under halogen light were performed and, the recyclability of the sample is investigated. It was found from the photocatalytic spectrum that, the samples prepared from both the methods shows a degradation efficiency of more than 80% within 150 min. It was confirmed that the prepared NiV2O6 photocatalyst samples does not lose their degradation ability even after five cycles of repeated usage.

Reduced graphene oxide supported NiCo2O4 nanocomposite bifunctional electrocatalyst for glucose-oxygen fuel cell

Reduced graphene oxide and nickel-cobalt oxide (rGO-NiCo2O4) nanocomposite material with optimized rGO is prepared via hydrothermal method as bifunctional electrocatalyst for glucose oxidation reaction (GOR) and oxygen reduction reaction (ORR). Systematic analytical characterization techniques are employed to confirm the formation and morphology of rGO-NiCo2O4. Electrochemical techniques are used to study the electrocatalytic GOR and oxygen ORR at rGO-NiCo2O4 nanocomposite modified glassy carbon (GC) electrode in 0.1 M NaOH. An optimum loading of rGO in rGO-NiCo2O4 nanocomposite modified electrode outperformed than that of GC/NiCo2O4, GC/Co3O4 and GC/NiO modified electrodes in terms of onset potential and current density towards GOR and ORR. Thus, rGO-NiCo2O4 is used as a bifunctional catalyst in glucose-oxygen fuel cell (GFC). The rGO-NiCo2O4 naonocomposite modified carbon foam electrode delivers a considerable power density of 0.9679 mW cm−2 and an OCV of 0.96 V in GFC under alkaline conditions with an anion exchange bridge.

In-site pulse electrodeposition of manganese dioxide/reduced graphene oxide nanocomposite for high-energy supercapacitors

Manganese dioxide/reduced graphene oxide (MnO2/RGO) nanocomposite material was synthesized by the in-situ anodic pulse electrodeposition method to fabricate symmetric supercapacitors. The effects of the pH value of the electrodeposition bath were considered on the properties of fabricated electrodes. Three pH values ​​of 4, 7, and 10 were evaluated, and physicochemical properties were studied using field-emission scanning and transmission electron microscopy, X-ray diffraction, Fourier-transform infrared spectroscopy, nitrogen gas sorption isotherm, and thermogravimetric analysis. The electrochemical evaluation was performed by galvanostatic charge/discharge (GCD), cyclic voltammetry (CV), and electrochemical impedance spectroscopy techniques. The results revealed that the MnO2/RGO nanocomposite prepared at pH = 7 (i.e., MGO7) exhibited a maximum specific capacitance of 693.4 F g−1 at a current density of 0.5 A g−1. The symmetric supercapacitor based on MGO7 was also assessed using GCD and CV tests. Its specific capacitances at current densities of 0.5 and 20 A g−1 were 577.9 and 290.0 F g−1, respectively. The symmetric supercapacitor maintained 79.2% of initial capacitance after 5000 consecutive charge/discharge cycles at a current density of 4 A g−1. The highest energy density of 80.3 Wh kg−1 at the power density of 0.625 kW kg−1 and the highest power density of 25 kW kg−1 at the energy density of 40.3 Wh kg−1 was achieved by the fabricated supercapacitor.