Atomistic Insights Into V─O─W Active Sites in SCR Catalysts via Advanced EPR Spectroscopy

The development of more efficient selective catalytic reduction (SCR) systems remains crucial for mitigating NO x emissions during the transition toward sustainable energy technologies. VO x /WO x /TiO 2 catalysts are widely used due to their high activity and robustness. Tungsten is believed to act as a promoter, enhancing surface acidity and regulating the dispersion of active VO x , yet its role in the reaction remains under debate. In this study, we employ a combination of advanced EPR techniques, to investigate reduced vanadium species under pseudo‐ in situ NH 3 ‐SCR conditions. Our results provide direct spectroscopic evidence for the coexistence of V⁴⁺─O─V⁵⁺ and V⁴⁺─O─W⁶⁺ surface dimers, their electronic structure, and distribution. Notably, the prevalence of V⁴⁺─O─W⁶⁺ moieties indicates that tungsten not only enhances vanadium dispersion but also actively promotes its reducibility through heteronuclear interactions. This study advances the molecular‐level understanding of the NH 3 ‐SCR catalysis and showcases the power of advanced EPR methods in elucidating structure–reactivity relationships in complex oxide systems.