Sb-Mediated Triple Enhancement Effects on Photothermal CO2 Hydrogenation Performance of ZnO and the Underlying Mechanism

Photothermal conversion of CO2 into valuable chemical feedstocks is a vital route for closing the carbon cycle. Nevertheless, it remains challenging to develop high-performance photocatalysts with strong light absorption, favorable photogenerated charge-carrier dynamics, and efficient adsorption and activation of reactant molecules. Herein, we report an innovative strategy for enhancing the photothermal CO2 hydrogenation performance of ZnO via Sb-mediated triple-functional modification, resulting in an Sb/Sb2O3/Sb-ZnO ternary heterojunction photocatalyst. The triple functions are as follows: metallic Sb serves as an efficient light-harvesting site to promote the generation of photogenerated electron-hole pairs; Sb doping into ZnO moderately facilitates the generation and transport of photogenerated charge carriers; the S-scheme heterojunction formed between Sb2O3 and Sb-doped ZnO enables efficient charge separation and suppresses charge recombination. Furthermore, the synergistic effect of the ternary heterojunction facilitates adsorption and activation of CO2 and H2 molecules. As a result, the optimized catalyst reaches a CO production rate of 533.37 μmol·g–1·h–1, about 17 times higher than that of pristine ZnO, with nearly 100% CO selectivity. Meanwhile, the photocatalyst effectively inhibits the inherent photocorrosion of ZnO and exhibits outstanding stability. This work provides a feasible strategy for constructing multicomponent heterojunction photocatalysts with synergistic multifunctional properties.