Rapid Electron Migration by Oxygen Vacancy from the Substitution of N for O in BaTiO₃ to Boost Piezoelectric Catalytic Hydrogen Evolution and Degradation

Introducing heterogeneous elements into the lattice of materials to form oxygen vacancies can regulate the local electron density on their surfaces and enhance their piezoelectric catalytic performance. However, avoiding the use of highly reducing substances while regulating defects through a mild strategy remains a major challenge. This work synthesized defect-state BaTiO3 piezoelectric catalytic materials through a two-step solvent-free strategy and annealing under different atmospheres. The experimental results indicate that oxygen vacancies not only increase the free charge density of the material itself but also serve as "electron traps", promoting the directional transfer of electrons and significantly improving the separation efficiency of charge carriers. It is worth mentioning that BTO-OV-1 synthesized under nitrogen atmosphere exhibits enhanced piezoelectric catalytic activity due to abundant oxygen defects, with a yield of 504 μmol·g–1 of H2 generated by piezoelectric catalytic splitting of water within 100 min, and also exhibits excellent performance in piezoelectric catalytic degradation of organic pollutants. This study enriches the experimental devices for regulating oxygen vacancies and has a certain reference value for expanding the application research of highly active BaTiO3 materials in the field of piezoelectric catalysis.