Bismuth titanate microplates with tunable oxygen vacancies for piezocatalytic hydrogen peroxide production

Piezocatalysis offers an encouraging alternative for the sustainable, on-demand, and decentralized production of hydrogen peroxide (H₂O₂), underscoring the importance of enhancing piezocatalytic efficiency. Enhancing piezocatalysts through defect engineering has shown considerable potential in boosting H₂O₂ production efficiency. However, the impact of oxygen vacancies on piezocatalytic activity remains unclear. Herein, we used a chemical probe method to quantify negative charges (q⁻) and superoxide radicals ([rad]O₂⁻) to explore the relation between the oxygen vacancy concentration and piezocatalytic performance of bismuth titanate (Bi₄Ti₃O₁₂) based catalysts. Results indicate that piezocatalytic H₂O₂ production in pure water demonstrates a volcanic trend with increasing oxygen vacancy concentration. This trend is attributed to the dual role of oxygen vacancies, which reduce the piezoelectric property of the piezocatalyst while simultaneously increasing the concentration of [rad]O₂⁻, which is crucial for H₂O₂ formation through the O₂ reduction pathway. This study provides insights into the interplay between oxygen vacancies, piezoelectric properties, and piezocatalytic activity, offering valuable guidance for the design of piezocatalysts for sustainable H₂O₂ production.