Interfacial microenvironment and catalyst modulation for efficient hydrogen peroxide synthesis <i>via</i> mimicking oxidase catalysis

The two-electron oxygen reduction reaction driven by nanocatalysts that mimic formic acid oxidase catalysis is a promising approach for H₂O₂ synthesis under mild conditions without using light or electricity. However, in conventional reaction systems, the activity of the nanocatalysts and the production rate of H₂O₂ are generally restricted by the slow diffusion rate and low solubility of the reactant O₂ in water. Thus, it is of crucial importance to develop an efficient catalytic system that can address the O₂ deficiency issue, help to explore the intrinsic activity of catalysts and maximize their catalytic performance. In this study, combining interface microenvironment and material modulation, we fabricated an air-liquid-solid triphase reaction system that allows the rapid delivery of O₂<i>via</i> the air phase to the reaction zone, and synthesized a series of Au_<i>x</i>Pt_100-<i>x</i>-TiO₂ nanocatalysts for efficient H₂O₂ generation. We constructed a theoretical model to simulate O₂ concentration in different reaction conditions. Combined with experiments, it reveals that the interfacial O₂ concentration of the triphase system is much higher than that of the conventional solid-liquid diphase system. The triphase system maximizes the performance difference between catalysts, and enables us to discover that the Au₉₃Pt₇-TiO₂ catalyst exhibits the highest H₂O₂ production rate (4.43 mmol g^-1 h^-1) under mild conditions. The synergistic effect between the interface architecture and the catalyst leads to a 5-fold enhancement in H₂O₂ productivity.