Palladium single atoms: engineering asymmetric active sites for selective photothermal reduction of carbon dioxide to methanol

Photothermal (PT) synergistic catalysis for the conversion of CO 2 to methanol (MeOH) represents a promising strategy for CO 2 utilization. However, the development of Cu-ZnO catalysts exhibiting high thermal stability and photocatalytic activity remains a critical challenge for efficient CO 2 conversion via the PT catalysis. To address these issues, Pd single atoms are successfully anchored onto the Cu-ZnO surface of the Z -scheme heterostructure (designated as Pd 1 /Cu-ZnO), resulting in three distinct asymmetric coordination environments: Pd-O-Cu, Pd-Cu, and Pd-O-Zn. The non-uniform charge distribution at the Pd-Cu site on Pd 1 /Cu-ZnO enhances the adsorption and dissociation of H 2 , while the Pd-O-Zn site simultaneously optimizes the CO 2 adsorption configuration, thereby promoting significant elongation of the C=O bond. The band structures of semiconductors (CuO and ZnO) are modulated by Pd single atoms, which simultaneously enhances the localized surface plasmon resonance (LSPR) effect for Cu 0 , thereby improving Pd 1 /Cu-ZnO light response. The MeOH yield achieved with Pd 1 /Cu-ZnO as the catalyst is 1.45 times greater in the PT catalytic reaction compared to the thermal catalytic reaction, reaching 332.1 mmol·g −1 Cu·h −1 , while the selectivity increased from 50.1% to 87.2%, highlighting the exceptional performance of the single atom asymmetric sites. This study underscores the crucial role of single atoms in PT synergistic catalysis, demonstrating their superior potential for enhancing CO 2 utilization under mild conditions and improving atomic economy.