Highly Efficient Photocatalytic CO2 Methanation over Ru-Doped TiO2 with Tunable Oxygen Vacancies

Solar-driven CO(2)methanation is an imperative and promising approach to relieve the global warming and environmental crisis, yet remains a great challenge due to the low reaction efficiency, unsatisfactory selectivity and poor stability. In this work, we demonstrate a facile and efficient strategy to prepare Ru-doped TiO2 photocatalyst with tunable oxygen vacancies using the ascorbic acid as a reducing agent for the CO2 methanation reaction. The optimal Ru-TiO2-OV-50 exhibits a remarkable CH4 production rate of 81.7 mmol g(-1) h(-1) with a 100% CH4 selectivity under a 1.5 W cm(-2) light illumination, which is significantly higher than commercial Ru/TiO2 and other reported catalysts. We reveal that the superior photocatalytic CO2 methanation performance is mainly due to the synergistic effect of Ru doping and TiO2 with tunable oxygen vacancies. Impressively, the light rather than thermal effect is confirmed as the main influencing factor by experimental studies. In addition, in situ spectroscopic technology is performed to investigate the CO2 methanation reaction pathway. This work will open an avenue to design and prepare highly efficient photocatalyst with tunable oxygen vacancies for CO2 conversion and other related applications.

Automated summary

In this work, a facile and efficient strategy is demonstrated to prepare Ru-doped TiO2 photocatalyst for solar-driven CO2 methanation. The optimized Ru-TiO2-OV-50 exhibits remarkable CH4 production rate and selectivity under light illumination, outperforming commercial Ru/TiO2 and other reported catalysts. The superior performance is attributed to the synergistic effect of Ru doping and TiO2 with tunable oxygen vacancies. Light rather than thermal effect is confirmed as the main influencing factor. In addition, in situ spectroscopic technology is used to investigate the reaction pathway.