Piezoelectric Effect and Z-Scheme Charge Transfer in BaTiO ₃ /BiOCl Heterojunctions for Photocatalytic CO ₂ -to-CO Conversion

Artificial photosynthesis provides a sustainable route for the synthesis of high-value chemicals from CO2, yet its efficiency remains limited by low light utilization and fast charge recombination. Here, a direct Z-scheme BaTiO3/BiOCl (BTO/BOC) heterojunction was prepared using a hydrothermal synthesis route. Owing to the combined effects of piezoelectric polarization and Z-scheme charge transfer, the heterojunction achieved a CO2 reduction rate of 56.45 μmol g–1 h–1 under simultaneous application of light and ultrasonic irradiation, corresponding to 2.06- and 7.49-fold enhancements compared with pure BiOCl (BOC) nanosheets and BaTiO3 (BTO) nanoparticles, respectively. This study demonstrates a piezoelectric-assisted photocatalytic strategy, providing valuable insights into efficient CO2 conversion and sustainable energy development.