De Novo monolayer graphene oxide high-yield synthesis and Rietveld analysis for advanced energy storage applications

Abstract

Graphene oxide (GO) is a two-dimensional carbon material with a single-layered structure derived from graphene, ideal for efficient charge transfer in energy storage applications. This research presents a novel streamlined Hummers’ method for high-yield synthesis of monolayer GO sheets via low-temperature isopycnic centrifugation. GO sheets were heat treated (60${}^{\circ }$, 90${}^{\circ }$ and 120${}^{\circ }$) for varying durations (12 h, 16 h, and 20 h) and characterized by X-ray diffractometer to select purely monolayer samples, GO-12 and GO-22 (stacking height$\simeq$ 3.87 nm and 3.51 nm, respectively). The Rietveld analysis further confirmed that the hexagonal GO lattice corresponds to ‘P6mm’ space group. High-resolution transmission electron microscopy corroborated the micromorphology of purely isolated monolayer GO sheets and quantified the interplanar spacing. Micro-Raman spectroscopy corroborated the extent of graphitic domain disruption, as evidenced by the I${}_D$/I${}_G$ ratio of 0.87. Electrochemical investigations using cyclic voltammetry, galvanostatic charging/discharging, and electrochemical impedance spectroscopy demonstrated maximum specific capacitance of 1688.43 F g⁻¹ for GO-22 at 10 mV s⁻¹ with an energy density of 540.96 W h kg⁻¹ at a power density of 4.00 kW kg⁻¹, with capacitance retention of 92.16% after 10,000 cycles. This efficient method produces high-quality monolayer GO sheets, reducing costs, enhancing scalability, and supporting broader market adoption for advanced energy storage applications.