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

Abstract

Photocatalytic conversion of CO₂ to CH₄, 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 H₂ by side reactions. The design of catalytic sites for CO₂ adsorption and activation holds the key to address this grand challenge. In this Article, we develop highly selective sites for photocatalytic conversion of CO₂ to CH₄ 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 CO₂-to-CH₄ conversion: (1) providing the paired Cu-Pd sites for the enhanced CO₂ adsorption and the suppressed H₂ evolution; and (2) elevating the d-band center of Cu sites for the improved CO₂ activation. As a result, the Pd₇Cu₁-TiO₂ photocatalyst achieves the high selectivity of 96% for CH₄ 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 CO₂ conversion, and highlights the importance of catalyst lattice engineering at atomic precision to catalytic performance.