Ecofriendly Chemical Reduction of Graphene Oxide using Ascorbic Acid: Synthesis and Characterization of Graphene Nanosheets for Battery Electrodes

International Journal of Research in Engineering & Science ISSN:(P) 2572-4274 (O) 2572-4304 Available online on http://rspublication.com/IJRES/IJRE.html volume 9 Number 6, 2025 DOI: 10.5281/zenodo.17542214 Original Article ©2025 RS Publication, [email protected] 23 Ecofriendly Chemical Reduction of Graphene Oxide using Ascorbic Acid: Synthesis and Characterization of Graphene Nanosheets for Battery Electrodes G. D. Atung 1* , A. D. A. Buba 1 , D. O. Samson 1 , and A. M. Ramalan 1 1 Department of Physics, University of Abuja, Abuja, Nigeria ARTICLE INFO ABSTRACT ©2025 RS Publication Paper ID: IJRES6906758FE8EF5 Received: 2025-10-03 Published: 2025-11-06 DOI: https://dx.doi.org/ 10.5281/zenodo.1754 2214 Page No: 23-36 The escalating demand for advanced energy storage systems has spurred research into highperformance electrode materials, with graphene nanosheets emerging as the most effective material due to their exceptional electrical conductivity, high surface area, and substantial mechanical properties. This original research involved the synthesis and characterization of graphene nanosheets through the chemical reduction of graphene oxide (GO), with an emphasis on ecofriendly methodologies and their application in electrodes for batteries and supercapacitors. The chemical reduction of GO was performed by reducing graphite through oxidative processes to produce graphene nanosheets. The synthesis process involved oxidizing graphite to form GO using sulfuric acid, phosphoric acid, and potassium permanganate, followed by reduction to restore the sp² carbon network. The chemical reduction involved the use of environmentally benign reducing agents, namely ascorbic acid and plant extracts. The advanced characterization techniques, including Scanning Electron Microscopy (SEM), X-ray Diffraction (XRD), and Raman Spectroscopy, were employed to analyze the structural and morphological properties of the synthesized nanosheets. SEM revealed agglomerated, porous nanosheets with partial restacking, ideal for enhancing electrochemical performance, and XRD confirmed the restoration of the sp² network with a broad (002) peak, indicating few-layer graphene, while Raman spectra displayed characteristic D, G, and 2D bands, reflecting moderate defect density typical of chemically reduced graphene. The results demonstrate successful exfoliation and reduction of GO, with the nanosheets exhibiting properties suitable for electrode applications. Hence, by optimizing reduction techniques and adopting sustainable practices, this research addresses challenges in large-scale synthesis, quality control, and environmental impact, contributing to the development of high-quality graphene nanosheets for energy storage. The findings establish and recommend that the chemical reduction technique is a scalable, ecofriendly production method, bridging the gap between laboratory research and industrial applications, and advancing the performance of next-generation energy storage devices. Keywords: Graphene nanosheets, rGO, CVD, XRD, SEM.. Corresponding Author: Gabriel Douglas Atung * , Department of Physics, University of Abuja, Abuja, Nigeria. International Journal of Research in Engineering & Science Available online on http://rspublication.com/IJRES/IJRE.html ISSN:(P) 2572-4274 (O) 2572-4304 Cite This Paper: Gabriel Douglas Atung, A. D. A. Buba, D. O. Samson, and A. M. Ramalan (2025). "Ecofriendly Chemical Reduction of Graphene Oxide using Ascorbic Acid: Synthesis and Characterization of Graphene Nanosheets for Battery Electrodes". INTERNATIONAL JOURNAL OF RESEARCH IN ENGINEERING & SCIENCE (IJRES), vol. 9, no. 5, 2025, pp. 23-36. DOI: https://dx.doi.org/10.5281/zenodo.17542214 International Journal of Research in Engineering & Science ISSN:(P) 2572-4274 (O) 2572-4304 Available online on http://rspublication.com/IJRES/IJRE.html volume 9 Number 6, 2025 DOI: 10.5281/zenodo.17542214 Original Article ©2025 RS Publication, rspublicationh[email protected] 24 The quest for advanced materials for electrode applications has led researchers to explore versatile and cost-effective methods of producing graphene nanosheets. Graphene been one of the substantial and scalable materials, a single layer of carbon atoms arranged in a hexagonal lattice, possesses exceptional electrical conductivity, high surface area, and superior mechanical properties, making it a highly desirable material for energy storage devices such as batteries and supercapacitors.[1, 2] Despite the promising applications of graphene nanosheets in electrode materials, their commercial viability is hindered by challenges in large-scale synthesis and quality control. Traditional reduction methods often involve hazardous chemicals, posing environmental and safety risks. Additionally, achieving consistent structural and electronic properties in the reduced graphene oxide remains a technical hurdle. Among the various approaches for synthesizing graphene, the chemical reduction of graphene oxide (GO) stands out due to its simplicity, scalability, and relatively low cost. Graphene oxide, derived from graphite through oxidative processes, serves as an ideal precursor for graphene nanosheets.[2-4] The reduction of GO constitutes the removal of the functionalized oxygencontaining groups and the restoration of the graphene structure, which enhances its electrical conductivity.[5] This method is particularly attractive for applications in electrodes, as it allows for fine-tuning the properties of graphene to meet specific performance criteria.[2, 5] Recent advancements have focused on optimizing the reduction process to improve the quality of the resulting graphene nanosheets while minimizing the environmental impact. The use of 1. INTRODUCTION International Journal of Research in Engineering & Science ISSN:(P) 2572-4274 (O) 2572-4304 Available online on http://rspublication.com/IJRES/IJRE.html volume 9 Number 6, 2025 DOI: 10.5281/zenodo.17542214 Original Article ©2025 RS Publication, rspublicationh[email protected] 25 environmentally benign reducing agents, such as ascorbic acid and plant extracts, has gained attention as an alternative to traditional chemical reducing agents like hydrazine, which are toxic and hazardous. [6] This study aims to address these challenges by exploring ecofriendly reduction techniques and thoroughly characterizing the synthesized graphene nanosheets. This study delves into the synthesis and characterization of graphene nanosheets via the chemical reduction of graphene oxide, with a particular focus on their application in electrodes. The objectives are to: i. Investigate and optimize reduction techniques using environmentally benign agents (ascorbic acid and plant extracts). ii. Synthesize reduced graphene oxide (rGO) from graphene using the chemical reduction method. iii. Characterize the synthesized rGO using advanced techniques, namely SEM, XRD, and Raman spectroscopy. 2.1. Chemicals and Reagents The chemicals and reagents used in this study include graphite powder as the carbon source, concentrated sulfuric acid (H₂SO₄) and phosphoric acid (H₃PO₄) as the acidic medium for oxidation, and potassium permanganate (KMnO₄) as the oxidizing agent. Hydrogen peroxide (H₂O₂, 30%) was employed to terminate the oxidation reaction, while hydrochloric acid (HCl, 37%) was used for washing and purification. A reducing agent, such as ecofriendly alternatives like ascorbic acid or plant extracts, was utilized for the chemical reduction of graphene oxide. 2. MATERIAL AND METHODS International Journal of Research in Engineering & Science ISSN:(P) 2572-4274 (O) 2572-4304 Available online on http://rspublication.com/IJRES/IJRE.html volume 9 Number 6, 2025 DOI: 10.5281/zenodo.17542214 Original Article ©2025 RS Publication, rspublicationh[email protected] 26 Deionized water was used throughout the synthesis and purification processes to remove impurities and maintain reaction consistency. 2.2 Apparatus and Equipment The experimental procedures were carried out using a range of laboratory equipment, including a magnetic stirrer with a hot plate for controlled heating and mixing, an ultrasonicator for dispersing graphene oxide in aqueous media, and a centrifuge for separation and purification steps. A vacuum filtration setup was used for solid-liquid separation, and a furnace was used to dry the synthesized materials at controlled temperatures. An analytical balance ensured precise measurement of reagents, and standard laboratory glassware such as beakers, conical flasks, and volumetric flasks supported the preparation and handling of chemical solutions. 2.3 Synthesis of Graphene Oxide (GO) Graphene oxide was synthesized using a modified Hummers method [2, 7, 8]. A mixture of sulfuric acid and phosphoric acid was prepared, into which graphite powder was gradually added under continuous stirring. Potassium permanganate was then introduced slowly while maintaining the temperature below 10°C to prevent overheating. The reaction mixture was subsequently heated to 50°C and stirred for 12 hours to facilitate oxidation. After cooling to room temperature, ice and hydrogen peroxide were added, resulting in a bright yellow solution that indicated successful oxidation of graphite to graphene oxide. The resulting mixture was diluted with deionized water and subjected to centrifugation at 4000 rpm. The solid product was washed repeatedly with 1 M hydrochloric acid and deionized water International Journal of Research in Engineering & Science ISSN:(P) 2572-4274 (O) 2572-4304 Available online on http://rspublication.com/IJRES/IJRE.html volume 9 Number 6, 2025 DOI: 10.5281/zenodo.17542214 Original Article ©2025 RS Publication, rspublicationh[email protected] 27 until a neutral pH was achieved, ensuring the removal of residual acids and metal ions. Finally, the purified graphene oxide slurry was dried in a furnace at 60°C to obtain dry GO powder for further processing. Figure 1: Synthesis of reduced graphene oxide International Journal of Research in Engineering & Science ISSN:(P) 2572-4274 (O) 2572-4304 Available online on http://rspublication.com/IJRES/IJRE.html volume 9 Number 6, 2025 DOI: 10.5281/zenodo.17542214 Original Article ©2025 RS Publication, rspublicationh[email protected] 28 2.4 Characterization of the Graphene Oxide In addition to the synthesis and reduction procedures, advanced characterization techniques were employed to analyze the structural and morphological properties of the synthesized graphene materials. Scanning Electron Microscopy (SEM) was used to observe the surface morphology and layer structure of the graphene nanosheets. X-ray Diffraction (XRD) provided insights into the crystallinity and interlayer spacing, confirming the successful oxidation and subsequent reduction of graphite. Raman spectroscopy was conducted to evaluate the defect density and restoration of the sp² carbon network, with particular attention to the D and G band intensity ratios. These methods collectively ensured a comprehensive understanding of the material’s transformation and suitability for energy storage applications. 3.1 SEM Analysis of Graphene Nanosheets Scanning Electron Microscopy (SEM) was conducted to investigate the surface morphology and microstructure of the synthesized graphene nanosheets. The micrographs reveal distinct morphological features across varying magnifications. At lower magnifications (40 µm and 60 µm), the graphene nanosheets appear as loosely stacked clusters with wrinkled and crumpled textures, indicative of exfoliated layers and high surface area. The red-circled region highlights a densely packed flake structure, indicating localized agglomeration. At higher magnifications (80 µm and 100 µm), the nanosheets exhibit more fibrous and layered arrangements, with visible folds and ridges that are characteristic of reduced graphene oxide. These features confirm successful exfoliation and reduction, as well as the preservation of the sheet-like 3. RESULTS AND DISCUSSION International Journal of Research in Engineering & Science ISSN:(P) 2572-4274 (O) 2572-4304 Available online on http://rspublication.com/IJRES/IJRE.html volume 9 Number 6, 2025 DOI: 10.5281/zenodo.17542214 Original Article ©2025 RS Publication, rspublicationh[email protected] 29 architecture essential for electrochemical applications. The porous and interconnected morphology observed across the samples suggests enhanced ion transport pathways, making the material suitable for use in battery electrodes and other energy storage systems. Figure 2: SEM analysis of graphene nanosheets International Journal of Research in Engineering & Science ISSN:(P) 2572-4274 (O) 2572-4304 Available online on http://rspublication.com/IJRES/IJRE.html volume 9 Number 6, 2025 DOI: 10.5281/zenodo.17542214 ©2025 RS Publication, [email protected] 30 Original Article X-ray Diffraction (XRD) analysis was performed to investigate the crystalline structure and phase purity of the synthesized graphene nanosheets. The diffraction pattern displays two prominent peaks: one at approximately 26.5°, corresponding to the (002) plane, and another at around 43.5°, attributed to the (100) plane. The (002) peak indicates the presence of graphitic layers and confirms the partial restoration of the sp² carbon network following reduction. The (100) peak reflects inplane structural ordering, further validating the formation of reduced graphene oxide (rGO) with improved crystallinity. These results demonstrate successful reduction and structural integrity of the graphene nanosheets, making them suitable for applications in energy storage and electronic devices. Figure 3: XRD analysis of graphene nanosheets International Journal of Research in Engineering & Science ISSN:(P) 2572-4274 (O) 2572-4304 Available online on http://rspublication.com/IJRES/IJRE.html volume 9 Number 6, 2025 DOI: 10.5281/zenodo.17542214 ©2025 RS Publication, [email protected] 31 Original Article 3.2 Raman Spectroscopy Analysis of Graphene Nanosheets Raman spectroscopy was employed to assess the structural integrity and defect characteristics of the synthesized graphene nanosheets (GNS). The spectrum reveals three prominent peaks: the D band (~1350 cm⁻¹), the G band (~1580 cm⁻¹), and the 2D band (~2700 cm⁻¹). The D band is indicative of structural defects and disorder within the graphene lattice, commonly observed in reduced graphene oxide due to incomplete restoration of the sp² carbon network. The G band corresponds to the in-plane vibrational modes of sp² carbon atoms and reflects the graphitic nature of the material. The 2D band, a second-order overtone of the D band, provides insight into the stacking order and number of graphene layers. Its broad and relatively low intensity suggests the presence of multilayer graphene with some degree of stacking. Overall, the Raman spectrum confirms the successful reduction of graphene oxide and highlights the structural features relevant for energy storage applications. Figure 4: Raman spectroscopy of graphene nanosheets