Trends in C–O and N–O bond scission on rutile oxides described using oxygen vacancy formation energies

摘要

Reactivity trends on transition metals can generally be understood through the d-band model, but no analogous theory exists for transition metal oxides. This limits the generality of analyses in oxide-based catalysis and surface chemistry and has motivated the appearance of numerous descriptors. Here we show that oxygen vacancy formation energy (Δ E _(Vac) ) is an inexpensive yet accurate and general descriptor for trends in transition-state energies, which are usually difficult to assess. For rutile-type oxides (MO _(2) with M = 3d metals from Ti to Ni), we show that Δ E _(Vac) captures the trends in C–O and N–O bond scission of CO _(2) , CH _(3) OH, N _(2) O, and NH _(2) OH at oxygen vacancies. The proportionality between Δ E _(Vac) and transition-state energies is rationalized by analyzing the oxygen–metal bonds, which change from ionic to covalent from TiO _(2) to NiO _(2) . Δ E _(Vac) may be used to design oxide catalysts, in particular those where lattice oxygen and/or oxygen vacancies participate in the catalytic cycles.