Synergy of ferroelectric polarization and oxygen vacancy to promote CO photoreduction.

Solar-light driven CO reduction into value-added chemicals and fuels emerges as a significant approach for CO conversion. However, inefficient electron-hole separation and the complex multi-electrons transfer processes hamper the efficiency of CO photoreduction. Herein, we prepare ferroelectric BiTiNbO nanosheets and employ corona poling to strengthen their ferroelectric polarization to facilitate the bulk charge separation within BiTiNbO 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 CO molecules on the catalysts' surface. More importantly, the oxygen vacancies exert a pinning effect on ferroelectric domains that enables BiTiNbO nanosheets to maintain superb ferroelectric polarization, tackling above-mentioned key challenges in photocatalytic CO 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 CO photoreduction performance.