Unexpected Redox Role of WO ₃ in V ₂ O ₅ ‐WO ₃ /TiO ₂ Catalysts for Selective Reduction of NO by Forming V–W Dinuclear Sites

Abstract 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 WO 3 in V 2 O 5 ‐WO 3 /TiO 2 catalysts acts as a promoter to enhance the surface acidity and regulate the dispersion of active V 2 O 5 species, while it is believed that the redox process takes place entirely at the V sites in the selective catalytic reduction of NO x with NH 3 (NH 3 ‐SCR). Here, by combining in situ spectroscopic measurements and density functional theory (DFT) calculations, we validate that the WO 3 directly participates in the oxidative activation of NH 3 , and hence explicitly exerts a redox effect in NH 3 ‐SCR by forming V–W dinuclear sites with V 2 O 5 . This study sheds new light on a long‐standing puzzle regarding the role of WO 3 as a promoter and hence advances the understanding of the working principle of V 2 O 5 ‐WO 3 /TiO 2 catalysts.