Overlayer-Engineered BiVO₄ Suppresses H₂O₂ Decomposition to Enable Sustained Photocatalytic Production

Inorganic semiconductor photocatalysts are highly promising for hydrogen peroxide (H₂O₂) production due to their inherent robustness against radical oxidation. However, the rapid surface-mediated decomposition of H₂O₂ in pure water remains a critical bottleneck for sustained production. This study demonstrates that an amorphous metal oxide overlayer strategy can effectively suppress H₂O₂ decomposition on Mo-doped BiVO₄ (BiVO₄:Mo) photocatalyst, enabling enhanced and sustained H₂O₂ production. It is revealed that an amorphous TiO₂ thin layer on BiVO₄:Mo not only weakens H₂O₂ adsorption but also inhibits the activation of adsorbed H₂O₂ molecules, leading to a decrease in the decomposition rate constant to only ∼13% of its pristine counterpart. Meanwhile, the amorphous TiO₂ overlayer maintains the photocatalytic activities for two-electron oxygen reduction and four-hole water oxidation by enabling effective charge transfer while remaining permeable to water and oxygen. Consequently, the Au/TiO₂/BiVO₄:Mo photocatalyst achieves a threefold increase in the yield compared to the unmodified Au/BiVO₄:Mo. Furthermore, the effectiveness of other amorphous metal oxides, such as SiO₂ and Nb₂O₅, underscores the universality of this amorphous overlayer strategy. This work provides a general method for sustained H₂O₂ production over BiVO₄ photocatalysts, offering broad potential for efficient solar energy conversion.