Synergistic Pd species anchored in ordered macroporous In2O3 boosting solar-driven CO2 and H2O conversion

Achieving efficient photocatalytic CO 2 reduction using H 2 O as a hydrogen source requires the synergistic optimization of both charge and proton transfer between CO 2 reduction and H 2 O oxidation half-reactions. However, conventional studies mostly focused on enhancing these half-reactions independently, overlooking the intrinsic interdependence between them. Herein, this work develops a photothermal catalyst (denoted as Pd 1+c /3DOM-In 2 O 3 ) through engineering synergistic Pd single atoms (Pd 1 ) and Pd clusters (Pd c ) in three-dimensional ordered macroporous (3DOM) In 2 O 3 framework. The mechanistic study reveals that the coexistence of Pd single atoms and clusters not only offers synergistic active sites to promote the reaction of CO 2 and H 2 O, but also substantially improves the separation and transfer efficiencies of photogenerated electrons and holes. The Pd clusters facilitate H 2 O dissociation to ensure an adequate supply of active hydrogen species as well as synergistically enhance the adsorption and activation of CO 2 at Pd single-atom sites. Furthermore, the enhanced photoabsorption in visible and near-infrared regions, attributed to the localized surface plasmon resonance of Pd clusters, leads to a significant increase in catalyst temperature under simulated solar irradiation. The integration of photocatalysis with the photothermal effect affords an intensified driving force for the selective conversion of CO 2 and H 2 O into CO, thereby accelerating the reaction kinetics of the overall photocatalytic CO 2 reduction process. As a result, the Pd 1+c /3DOM-In 2 O 3 catalyst exhibits excellent performance for solar-driven CO 2 reduction with H 2 O vapor, achieving a remarkable CO production rate of 192.52 μmol g –1 h –1 , which is 19.8-fold and 12.2-fold higher than those of pure 3DOM-In 2 O 3 and Pd 1 /3DOM-In 2 O 3 , respectively. This study provides valuable insights into the synergistic effect of metal single atoms and clusters toward both efficient photocatalysis and photothermal effect for solar-driven CO 2 reduction.