Sn-Doped defect pyrochlore oxide KNbWO6·H2O microcrystals and their photocatalytic reduction of CO2

Abstract

It is highly desirable to develop new semiconductors for the photocatalytic reduction of CO₂ to CH₄ and CO to solve greenhouse effect and energy issues. Defect pyrochlore oxides have a flexible composition and the electron/hole mobility can be manipulated by introducing foreign cations into the structure. Through Sn doping into the defect pyrochlore oxide KNbWO₆·H₂O, we successfully obtained a 2-times higher photocatalytic activity for converting CO₂ to CO, CH₄ and O₂ compared to the original KNbWO₆·H₂O. According to the data from UV-vis, photoluminescence, and hydroxyl radical amount-related fluorescence spectra, and CO₂ adsorption, the improved photocatalytic activity can be attributed to the extended visible light response, the enhanced charge separation and the improved CO₂ adsorption due to Sn doping. Our results provide a new strategy for developing high-performance photocatalysts.