Isolation of Cu Atoms in Pd Lattice: Forming Highly Selective Sites for Photocatalytic Conversion of CO₂ to CH₄

Abstract

Photocatalytic conversion of CO 2 to CH 4, a carbon-neutral fuel, represents an appealing approach to remedy the current energy and environmental crisis; however, it suffers from the large production of CO and H 2 by side reactions. The design of catalytic sites for CO 2 adsorption and activation holds the key to address this grand challenge. In this Article, we develop highly selective sites for photocatalytic conversion of CO 2 to CH 4 by isolating Cu atoms in Pd lattice. According to our synchrotron-radiation characterizations and theoretical simulations, the isolation of Cu atoms in Pd lattice can play dual roles in the enhancement of CO 2 -to-CH 4 conversion: (1) providing the paired Cu–Pd sites for the enhanced CO 2 adsorption and the suppressed H 2 evolution; and (2) elevating the d -band center of Cu sites for the improved CO 2 activation. As a result, the Pd 7 Cu 1 –TiO 2 photocatalyst achieves the high selectivity of 96% for CH 4 production with a rate of 19.6 μmol g cat –1 h –1 . This work provides fresh insights into the catalytic site design for selective photocatalytic CO 2 conversion, and highlights the importance of catalyst lattice engineering at atomic precision to catalytic performance.