A Schottky Heterojunction with Spatially Separated Active Sites for Piezo-photocatalytic Dual-channel Hydrogen Peroxide Generation

Mechanical and solar energy-driven piezo-photocatalysis has drawn growing attention for H2O2 synthesis and related applications. However, most reported works focused on single pathway and ignored simultaneous oxygen reduction and water oxidation for H2O2 generation. Herein, Au-ZnO Schottky heterojunction is constructed for piezo-photocatalytic H2O2 synthesis via dual-channel pathway (simultaneous oxygen reduction and water oxidation). Experimental results and density functional theory calculations illustrated that the reduction and oxidation reactions predominantly take place at Au and ZnO sites, respectively. The spatially separated active sites avoid site competition, and enable a synergistic effect of oxidation and reduction. Furthermore, Au nanoparticles not only provide hot electrons via surface plasmon resonance effect, but also form Schottky junctions with ZnO to decrease the charge shielding effect. As a result, a H2O2 generation of 186 μM in pure water (30 min) is achieved by the optimal sample. This study provides a strategy for the construction of piezo-photocatalysts from the perspective of spatially separated redox sites for efficient H2O2 synthesis.