Unlocking the Origin of Enhanced Piezo-Photocatalytic Performance via Thermodynamic Insights: A Study of Surface Active-Site Engineering in ZnO

Engineering active sites to boost the catalytic performance of semiconducting materials is of current interest. Herein, the enhanced hydrogen peroxide (H₂O₂) production via oxygen (O₂) reduction through a surface-substituting strategy is reported, in which the surface Zn─O bonds are partially halogenated in the one-step simple calcination process. The experimental data validated the presence of halogen on the surface modulated the band structures of the prepared materials, leading to enhanced catalytic performance with the optimal samples, ZnO-Cl, generating up to 6.3 µmol h⁻¹ of H₂O₂ under piezo-photocatalytic conditions from pure water. In addition, theoretical calculation demonstrates the binding energy for the halogen-defecting surface would be more stable for the adsorption of O₂ than pristine ZnO. Furthermore, the thermodynamic states of piezo-catalytic, piezocatalytic, and photocatalytic conditions are also evaluated via the temperature-dependent aerobic degradation of methylene blue (MB). The results show that piezo-photocatalysis can help enhance catalytic performance by lowering the activation barrier, which would relate to the entropy-enthalpy compensation effects. This study not only provides a simple approach to synthesizing highly active catalysts to produce H₂O₂ but also interprets the fundamental insights into how ultrasound can enhance photocatalytic outcomes, benefiting both material and catalytic communities.