d <i> _xz </i> –p <i> _y </i> Orbital Interaction Mediated by Lattice-Strain Engineering for the Selective Catalytic Reduction of NH ₃

Reverse oxygen spillover plays a crucial role in redox catalysis, but its underlying mechanisms remain less elucidated than those of hydrogen spillover. Herein, the vanadium-supported mixed crystal phase of TiO2 is prepared by continuous-flow synthesis flame spray pyrolysis (FSP) via activating reverse oxygen spillover to promote the low-temperature NH3–SCR activity. The reverse oxygen spillover is mediated by the mixed crystal phase of TiO2, followed by the bond cleavage of Ti–O–V moieties nearby, which are more active in the catalytic reaction. Fast quenching and microsecond-scale high-temperature retention time contribute to the tensile strain of the mixed-phase titanium dioxide and oxygen spillover migration. A relatively stronger π* bonding state is composed of dxz–py hybridization on the sample prepared by FSP, which is conducive to the activation of ammonia molecules. This study explicitly reveals the interfacial chemistry of reverse oxygen spillover that is initiated via FSP, and the acquired insight aids in the rational design of vanadia/titania catalysts for diverse reactant systems.