Shaping and Doping Metal–Organic Framework-Derived TiO₂ to Steer the Selectivity of Photocatalytic CO₂ Reduction toward CH₄

Abstract

Steering selectivity in photocatalytic conversion of CO 2 , especially toward deep reduction products, is vital to energy and environmental goals yet remains a great challenge. In this work, we demonstrate a facet-dependent photocatalytic selective reduction of CO 2 to CH 4 in Cudoped TiO 2 catalysts exposed with different facets synthesized by a topological transformation from MIL-125 (Ti) precursors. The optimized round cake-like Cu/TiO 2 photocatalyst mainly exposed with the (001) facet exhibited a high photocatalytic CO 2 reduction performance with a CH 4 yield of 40.36 μmol g −1 h −1 with a selectivity of 94.1%, which are significantly higher than those of TiO 2 (001) (4.70 μmol g −1 h −1 and 52.6%, respectively), Cu/TiO 2 (001 + 101) (18.95 μmol g −1 h −1 and 69.6%, respectively), and Cu/TiO 2 (101) (14.73 μmol g −1 h −1 and 78.9%, respectively). The results of experimental and theoretical calculations demonstrate that the Cu doping dominating the promoted separation and migration efficiencies of photogenerated charges and the preferential adsorption on (001) facets synergistically contribute to the selective reduction of CO 2 to CH 4 . This work highlights the significance of synergy between facet engineering and ion doping in the design of high-performance photocatalysts with respect to selective reduction of CO 2 to multielectron products.