Synergy of ferroelectric polarization and oxygen vacancy to promote CO2 photoreduction

Solar-light driven CO₂ reduction into value-added chemicals and fuels emerges as a significant approach for CO₂ conversion. However, inefficient electron-hole separation and the complex multi-electrons transfer processes hamper the efficiency of CO₂ photoreduction. Herein, we prepare ferroelectric Bi₃TiNbO₉ nanosheets and employ corona poling to strengthen their ferroelectric polarization to facilitate the bulk charge separation within Bi₃TiNbO₉ nanosheets. Furthermore, surface oxygen vacancies are introduced to extend the photo-absorption of the synthesized materials and also to promote the adsorption and activation of CO₂ molecules on the catalysts' surface. More importantly, the oxygen vacancies exert a pinning effect on ferroelectric domains that enables Bi₃TiNbO₉ nanosheets to maintain superb ferroelectric polarization, tackling above-mentioned key challenges in photocatalytic CO₂ reduction. This work highlights the importance of ferroelectric properties and controlled surface defect engineering, and emphasizes the key roles of tuning bulk and surface properties in enhancing the CO₂ photoreduction performance.