In-situ generation of S-scheme heterojunction via A-Site defects reconstruction perovskite oxide for efficient CO₂ photoreduction

Photocatalytic conversion of CO₂ into fuels is a promising strategy for achieving carbon reduction. Designing catalysts with appropriate band edge positions and constructing suitable active sites to effectively activate CO₂ is highly desirable but still challenging. Here, we enhance the CO₂ reduction activity and selectivity of BaTi_0.7Co_0.3O₃ perovskite oxide by adjusting its bulk phase structure through the introduction of A-site vacancies. The structural distortion induced by Ba cation defects promotes the exsolution of Co ions, forming an intriguing S-scheme heterojunction composed of metal oxide-perovskite coupled nanoparticles. The charge carriers at the heterointerfaces are extracted and rapidly transferred to the surface-active sites. The separated redox sites overcome the trade-off between activity and selectivity, resulting in a CO₂ reduction activity five times higher than that of the pristine BaTi_0.7Co_0.3O₃, with a high CH₄ selectivity of 95.1 %. This work provides a new insight into the in-situ formation of heterostructures for efficient photocatalytic CO₂ reduction.