Engineering Catalytic Interfaces in Cu δ+ /CeO 2 -TiO 2 Photocatalysts for Synergistically Boosting CO 2 Reduction to Ethylene.

Photocatalytic CO 2 conversion into a high-value-added C 2 product is a highly challenging task because of insufficient electron deliverability and sluggish C-C coupling kinetics. Engineering catalytic interfaces in photocatalysts provides a promising approach to manipulate photoinduced charge carriers and create multiple catalytic sites for boosting the generation of C 2 product from CO 2 reduction. Herein, a Cu δ+ /CeO 2 -TiO 2 photocatalyst that contains atomically dispersed Cu δ+ sites anchored on the CeO 2 -TiO 2 heterostructures consisting of highly dispersed CeO 2 nanoparticles on porous TiO 2 is designedly constructed by the pyrolytic transformation of a Cu 2+ -Ce 3+ /MIL-125-NH 2 precursor. In the designed photocatalyst, TiO 2 acts as a light-harvesting material for generating electron-hole pairs that are efficiently separated by CeO 2 -TiO 2 interfaces, and the Cu-Ce dual active sites synergistically facilitate the generation and dimerization of *CO intermediates, thus lowering the energy barrier of C-C coupling. As a consequence, the Cu δ+ /CeO 2 -TiO 2 photocatalyst exhibits a production rate of 4.51 μmol -1 ·g cat -1 ·h -1 and 73.9% selectivity in terms of electron utilization for CO 2 to C 2 H 4 conversion under simulated sunlight, with H 2 O as hydrogen source and hole scavenger. The photocatalytic mechanism is revealed by operando spectroscopic methods as well as theoretical calculations. This study displays the rational construction of heterogeneous photocatalysts for boosting CO 2 conversion and emphasizes the synergistic effect of multiple active sites in enhancing the selectivity of C 2 product.