Oxygen vacancies in piezo-photocatalysts: synthesis, characterization, effect mechanism and application

The escalating consumption of fossil fuels and the worsening of environmental pollution have rendered the advancement of sustainable clean energy conversion technologies an urgent priority. Piezo-photocatalytic technology, which integrates piezoelectric and photoexcited properties, provides an efficient means of converting chemical energy by utilizing mechanical and solar energy. Oxygen vacancies (OVs), as a critical type of defect structure, play a significant role in enhancing piezo-photocatalytic performance by modifying the band structure, improving polarization effects, and providing additional active sites. This review comprehensively examines the formation methods and characterization techniques of OVs, alongside their mechanistic roles in piezo-photocatalytic technology. We discuss how OVs influence the band structure, dipole moments, and local electronic configurations. Furthermore, we summarize the applications of OVs in various fields, including water pollution degradation, hydrogen production, nitrogen fixation, and CO₂ reduction. Finally, we outline future research directions for OVs, focusing on precise synthesis methods, the development of novel piezoelectric materials, enhancement of stability, and the investigation of interactions between OVs and other local structures. We hope that this review will provide valuable insights for the continued development and application of OVs in piezo-photocatalysis.