Interface sites on vanadia-based catalysts are highly active for NOx removal under realistic conditions

TiO 2 -supported V 2 O 5 catalysts are commonly used in NO x reduction with ammonia due to their robust catalytic performance. Over these catalysts, it is generally considered that the active species are mainly derived from the vanadia species rather than the intrinsic structure of V-O-Ti entities, namely the interface sites. To reveal the role of V-O-Ti entities in NH 3 -SCR, herein, we prepared TiO 2 /V 2 O 5 catalysts and demonstrated that V-O-Ti entities were more active for NO x reduction under wet conditions than the V sites (V=O) working alone. On the V-O-Ti entities, kinetic measurements and first principles calculations revealed that NH 3 activation exhibited a much lower energy barrier than that on V=O sites. Under wet conditions, the V-O-Ti interface significantly inhibited the transformation of V=O to V-OH sites thus benefiting NH 3 activation. Under wet conditions, meanwhile, the migration of NH 4 + from Ti site neighboring the V-O-Ti interface to Ti site of the V-O-Ti interface was exothermic; thus, V-O-Ti entities together with neighboring Ti sites could serve as channels linking NH 3 pool and active centers for activation of NH 4 + . This finding reveals that the V-O-Ti interface sites on V-based catalysts play a crucial role in NO x removal under realistic conditions, providing a new perspective on NH 3 -SCR mechanism.