Oxygen vacancy mediated bismuth stannate ultra-small nanoparticle towards photocatalytic CO2-to-CO conversion

Photocatalytic CO2 reduction suffers from the weakness of high energy barrier, low efficiency and poor selectivity. Exploring effective strategy to enhance the adsorption and activation behavior of CO2 molecules is an alternative approach to boost CO2 photoreduction performance. In this work, abundant oxygen vacancies (VO) are introduced onto Bi2Sn2O7 nanoparticles (NPs) by decreasing their size down to about 4 nm. The VO mediated NPs exhibit a tremendous 8.1 times enhanced performance than the bulk counterpart towards CO2-to−CO conversion in pure water. This is attributed to fast charge diffusion and abundant Vo for effective CO2 adsorption and activation in the ultra-small nanoparticles. The VO mediated Bi2Sn2O7 NPs have electron back donation nature and optimized electronic structure for effectively activating CO2, which were demonstrated by density functional theory calculations. During the reduction process, the Vo can effeciently stabilize the COOH* intermediates, and also lower the energy barrier of CO desorption determining step.