Operando photoelectrochemical analysis of H<sub>2</sub>O<sub>2</sub> photoproduction: differentiating catalytic roles of metal nanoclusters and carbon dot-modified nanoclusters

The photocatalytic production of hydrogen peroxide (H₂O₂) <italic>via</italic> the oxygen reduction reaction (ORR) holds great significance in chemical engineering, agriculture, and national defense. However, the underlying influence of interfacial charge dynamics on catalytic performance remains poorly understood due to limitations in conventional characterization techniques. In this study, we employ thiolate-protected gold-silver metal nanoclusters (MNCs) and nitrogen-doped carbon dot-modified nanoclusters (MNCs/N-CDs) as model systems to investigate ORR selectivity and charge dynamics under light irradiation. This catalyst design leverages the self-oxidation behavior of thiolate ligands and the intrinsic ORR selectivity of nanoclusters to establish a clean and well-defined photocatalytic system. By integrating time-resolved transient photovoltage (TPV) spectroscopy and operando transient potential scanning (TPS) test, we demonstrate that N-CDs promote the separation and storage of photoinduced charge carriers, as well as enhance oxygen adsorption and activation on the catalyst surface, thereby significantly improving H₂O₂ production efficiency. These findings offer new mechanistic insights into the interplay between interfacial charge dynamics and photocatalytic performance, providing guidance for the rational design of advanced ORR catalysts.