Enhancing Hydrogen Peroxide Production via Operando Monitoring of Catalytic Interfaces in Alloy Nanocluster Photocatalysts

A deep understanding of the catalytic interfacial processes in nanoscale systems is essential for the rational design of nanocatalysts. Specifically, for the complex photocatalysis on hydrogen peroxide (H₂O₂) production, multi-key-factors govern the catalytic interface. This study adopts silver-doped gold nanoclusters (AuAgNCs) to illustrate the influence of trace doping on key interfacial processes at the catalytic interface by spectroscopic characterization methods, including femtosecond transient absorption spectroscopy (fs-TAS), transient photovoltage (TPV), transient potential scanning (TPS), and transient photo-induced current (TPC). The research demonstrates that: 1) Ag incorporation not only enhances oxygen adsorption but also promotes its self-activation by oxygen; 2) The band structure of AuNCs and AuAgNCs exhibits no significant variation; 3) Charge carrier separation is facilitated while recombination is suppressed on AuAgNCs; 4) The oxygen reduction reaction catalytic pathway remains unchanged. Furthermore, the calculations of the Butler-Volmer equation demonstrate the reaction rates on the AuAgNCs are twice as much as those on AuNCs, in accordance with the activity improvement results. This work, based on operando analysis on the photocatalytic interface of the Au-Ag alloy nanocluster photocatalyst, shows detailed and distinct effects of Ag doping on oxygen adsorption/activation, charge carrier kinetics, and interfacial distribution.