Enhancing Piezo-Catalytic Hydrogen Evolution on BiOCl through UV Irradiation

Hydrogen production from water using piezo-catalysis is increasingly popular, but it typically requires expensive noble metal cocatalysts to speed up the reactions. In this study, we found that a UV irradiation treatment on the piezoelectric material BiOCl enhances its H₂ evolution by 6.8 folds, from 0.41 to 2.81 mmol/g/h, even outperforming those loaded with noble metal cocatalysts. Our experiments and simulations revealed that UV irradiation prompts the in situ reduction of lattice Bi³⁺ in BiOCl, creating Bi metal nanoparticles on the surface. These nanoparticles serve as cocatalysts, enhancing hydrogen production by (1) capturing piezo-generated electrons from BiOCl with Bi's higher work function; (2) facilitating charge transfer between Bi and BiOCl due to their intimate contact; and (3) improving H₂ evolution kinetics due to Bi's more suitable H* adsorption strength. This UV-enhancement technique can be applied to various Bi-based materials (e.g., BiOBr, BiOI, and Bi₂WO₆, etc.) as well as piezo-catalytic dye degradation reactions, demonstrating its versatility and potential for broader applications. This research provides a straightforward and cost-effective approach to improve the piezo-catalytic performance of Bi-based piezoelectric materials without the need for costly noble metal cocatalysts.