Electron-donating N−–Ti3+–Ov interfacial sites with high selectivity for the oxidation of primary C–H bonds

Abstract

Element doping can fabricate different types of oxygen vacancies (O v ) on TiO 2 , but the effects of O v coordination and configuration on the oxidation reaction remain unclear. Here, we modify the local geometric ligand environment of O v by doping N and B into anatase TiO 2 (N-TiO 2 and B-TiO 2 ). N − –Ti 3+ –O v is induced in N-TiO 2 by substituting O with N, which has similar ionic size and electronegativity, and Ti 3+ –O v is found in TiO 2 and B-TiO 2 . Density functional theory calculations indicate that N − –Ti 3+ –O v is more reactive than Ti 3+ –O v toward O 2 activation. The resultant N-TiO 2 -0.25 enriched in N − –Ti 3+ –O v contributes to a rapid formation of superoxygen species (•O 2 − ), which increase the oxidation rate of primary C–H bonds in toluene, and thus exhibits much higher selectivity and yield. The fabrication of N − –Ti 3+ –O v develops doped catalysts with improved O v reactivity and enhanced primary C–H bond oxidation selectivity. • N − –Ti 3+ –O v is more reactive than Ti 3+ –O v toward O 2 activation to generate ⋅O 2 − • The generation of ⋅O 2 − is the rate-determining step in selective oxidation of toluene • The introduced photo energy does not change the thermal selective oxidation process • A higher yield of products is attributed to the increased selective oxidation rate Oxygen vacancies in TiO 2 influence catalytic activity differently depending on their coordination environment. Chen et al. explore N and B doping and show that N − –Ti 3+ –O v is more reactive than Ti 3+ –O v toward O 2 activation, enhancing the primary C–H bond oxidation of toluene.