Unraveling the evolution of oxygen vacancies in TiO_(2–x)/Cu and its role in CO_(2)hydrogenation

The remarkable contribution of oxygen vacancies has been revealed by the operando spectroscopies for methanol synthesis from CO_(2)hydrogeneration on the reducible metal oxide-supported copper catalysts.However,a challenge remains in the intrinsic understanding of the evolution and advantage of oxygen vacancies for methanol synthesis.Here we prepare the TiO_(2–x)/Cu with different oxygen vacancy densities by adjusting the ball-milling frequency.At the optimal condition,a TiO_(2–x)/Cu with more oxygen vacancies delivers an excellent methanol yield of 26.5 mmol g^(-1)h^(-1)at 300℃with a selectivity of more than 70%.The combined analysis of experimental characterizations and theoretical calculations reveals that the mutual dispersions of TiO_(2–x)and Cu driven by mechanical energy induce the electron rearrangement in the d orbital of the Ti atom and relax the Ti–O binding at the interface,which facilitates the formation of oxygen vacancies that further reduce the barrier of CO_(2)hydrogenation to^(*)HCOO due to higher nucleophilicity of titanium ions.