Unexpected redox role of WO3 in V2O5‐WO3/TiO2 catalysts for selective reduction of NO by forming V‐W dinuclear sites

Promoters can greatly improve the activity of catalysts; however, the mechanism by which they interact with the primary catalyst to enhance catalytic activity is not always clear. It has been widely demonstrated that WO3 in V2O5‐WO3/TiO2 catalysts acts as a promoter to enhance the surface acidity and regulate the dispersion of active V2O5 species, while it is believed that the redox process takes place entirely at the V sites in the selective catalytic reduction of NOx with NH3 (NH3‐SCR). Here, by combining in situ spectroscopic measurements and density functional theory (DFT) calculations, we validate that the WO3 directly participates in the oxidative activation of NH3, and hence explicitly exerts a redox effect in NH3‐SCR by forming V‐W dinuclear sites with V2O5. This study sheds new light on a long‐standing puzzle regarding the role of WO3 as a promoter and hence advances the understanding of the working principle of V2O5‐WO3/TiO2 catalysts.