Unraveling the evolution of oxygen vacancies in TiO2−x/Cu and its role in CO2 hydrogenation

• Published in: Science China. Chemistry 2024-12, Vol.67 (12), p.4125-4133
• Main Authors: Wang, Ke, Zhang, Fanxing, Cao, Ning, Bao, Ying, Yan, Mi, Yan, Keping, Xie, Pengfei
• Format: Article
• Language: English
• Subjects: Ball milling; Carbon dioxide; Chemical synthesis; Chemistry; Chemistry and Materials Science; Chemistry/Food Science; Communications; Copper; Hydrogenation; Metal oxides; Methanol; Oxygen; Titanium; Titanium dioxide
• ISSN: 1674-7291; 1869-1870
• DOI: 10.1007/s11426-023-1995-6

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 °C 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.