Nanoparticle-Dependent Modulation of Interfacial Electron Transfer on Graphene Oxide Revealed at the Single-Particle Level

Elucidating how different nanocomponents regulate interfacial electron transfer on graphene oxide (GO) is crucial for the rational design of high-performance graphene-based electrodes. Here, SiO₂ nanoparticles, carbon nanospheres (CNS), and gold nanoparticles (Au NPs) are employed as representative modifiers to investigate their effects on the electrochemical performance and electron-transfer kinetics of GO. Macroscopic electrochemical measurements show that GO-Au composite electrodes exhibit the lowest overpotential and smallest charge-transfer resistance in the ascorbic acid oxidation reaction (AAOR), whereas SiO₂ markedly suppresses electron transfer and CNS has a limited effect. By integrating single-particle in situ fluorescence imaging, the oxidation and reduction electron-transfer rate constants of individual GO nanosheets are directly quantified and spatially mapped. The results reveal that SiO₂ significantly reduces local electron-transfer rates, Au NPs effectively promote electron transfer, and CNS shows minimal influence. A nanoparticle-dependent mechanistic model is proposed, providing single-particle-level insights for optimizing graphene-based composite electrodes.