Excellent photo-thermal synergistic catalytic performance: Controlled synthesis of Cu-ZnO catalyst featuring Z-scheme heterostructure

Abstract

The developing catalysts with Z-scheme heterostructure hold considerable potential for accelerating the thermodynamic processes of CO₂ capture and reduction. Nonetheless, the controlled synthesis of Cu-ZnO catalysts featuring Z-scheme heterostructure remains a formidable challenge. Herein, an advanced, rapid, and controllable photo-deposition method is developed to fabricate a reverse oxide/metal structure, which involves coating Cu clusters with a Cu oxide layer to produce Cu-ZnO catalyst characterized by typical Z-scheme heterostructures (Cu_xO-Cu-ZnO, abbreviated as Cu-ZnO-PD). The catalyst of the Cu_xO-Cu-ZnO structure exhibited remarkable thermal catalytic performance and achieved an 89.5 % increase in methanol yield under light irradiation (350–780 nm). Notably, the catalyst maintained structural stability even after the third catalytic reaction cycle. In-situ characterization and theoretical calculations show that when Cu_xO-Cu-ZnO is irradiated, generating a high-intensity photocurrent, which enhances H₂ adsorption on the catalyst surface and significantly reduces the free energy barrier for H₂ dissociation by 0.718 eV, thereby promoting H* spillover. Furthermore, photo-assisted thermal catalytic reaction alters the rate-determining step from the initial hydrogenation of HCOO* to the hydrogenation of HCOOH*, thus advancing the methanol synthesis pathway. This study presents a novel approach to synthesizing Cu-ZnO catalysts of Z-scheme heterostructure with high photo-thermal activity, broadening the potential applications of photo-thermal synergistic catalysts.