Construction of highly efficient Z-scheme ZnxCd1-xS/Au@g-C3N4 ternary heterojunction composite for visible-light-driven photocatalytic reduction of CO2 to solar fuel

Converting CO₂ into renewable solar fuel using photocatalysts is one of the most ideal solutions for environmental challenges and energy crises. Here, the solid-solid Z-scheme Zn_0.5Cd_0.5S/Au@g-C₃N₄ (ZCS/Au@CN) heterojunction showed improved photocatalytic reduction of CO₂ due to the enhanced visible light consumption, fast dissolution of photogenerated electron-hole pairs, quick interfacial transfer process of electrons, and enlarged surface area. Under visible-light irradiation, methanol (CH₃OH) was produced at a rate of 1.31 μmol h⁻¹ g⁻¹ over ZCS/Au@CN, roughly 43.6 and 32.7 folds higher than those observed over pure ZCS and CN samples. The analytical characterization results verified the role of AuNPs as an electron mediator, which improved the rapid extraction of photoinduced electrons and enhanced the reduction ability of CO₂. This work not only demonstrates a facile photodeposition assisted hydrothermal method for fabrication of Zn_xCd_1-xS/Au@C₃N₄ heterojunction composite photocatalysts but also demonstrates the possibility of utilizing ternary composites for enhanced photocatalytic reduction of CO₂.