Atomically-dispersed cobalt ions on polyphenol-derived nanocarbon layers to improve charge separation, hole storage, and catalytic activity of water-oxidation photoanodes

For efficient photoelectrochemical (PEC) water oxidation, tailorable modification of photoanodes with various functional layers is inevitably required to address the inherent limitations of the photoanodes. In this study, we report that N-doped graphene quantum dots derived from natural polyphenol tannic acid (N-TAGQDs) can form ultrathin and stable layers on a BiVO₄photoanode together with Co²⁺ions (BiVO₄/Co/N-TAGQD) by a simple dipping method and significantly improve PEC water-oxidation performance. A series of systematic analyses suggest the synergistic effect of graphitization of precursors to N-TAGQDs, N-doping, and the presence of phenolic groups to impart multifunctional roles of improving charge separation, hole storage, and catalytic activity. We believe that this simple method provides insights for the development of novel photoanodes and design of versatile carbon nanomaterials.