Understanding Nanoconfinement Effects on Electrochemical Redox Reactions with Reduced Graphite Oxide as a Model Electrode

Micropores smaller than 1 nm in carbon materials have garnered significant attention for their ability to induce confinement effects. Anomalous improvements in the specific capacitance and reversibility of electrochemical redox reactions have been reported. However, due to limitations in synthetic methods, carbon materials with identical physical properties but varying pore sizes have not yet been successfully prepared. In this study, we investigate the relationship between the pore size of carbon materials and the reversibility of the redox reaction of quinone-based molecules using reduced graphite oxide (rGO) as a model electrode material. Cross-linked graphite oxide (GO) and rGO exhibit minimal changes in surface properties while allowing precise tuning of the interlayer distance at the ångström level. The Δ<i>E</i>_p values of the redox reaction of quinone-based molecules on cross-linked rGO decrease with decreasing interlayer distance. These findings strongly indicate that the reversibility of the redox reaction can be enhanced by reducing the pore sizes of carbon materials. This study clearly demonstrates the origin of the relationship between the pore size and reversibility of the redox reactions of quinone-based molecules.