Z-scheme Au decorated carbon nitride/cobalt tetroxide plasmonic heterojunction photocatalyst for catalytic reduction of hexavalent chromium and oxidation of Bisphenol A

Highlights: • A novel Z-scheme Au/g-C₃N₄/Co₃O₄ plasmonic photocatalyst was achieved successfully. • Au/g-C₃N₄/Co₃O₄ shows superior photocatalytic activity for the removal of BPA and Cr⁶⁺. • The degradation pathway of BPA is proposed based on degradation products confirmed by GC-MS. • Z-scheme photocatalysis mechanism is proposed based on the experiments and simulations. Au/g-C₃N₄/Co₃O₄ plasmonic heterojunction photocatalyst was successfully prepared by in-situ forming Co₃O₄ nanocubes on the Au/g-C₃N₄ nanosheets. The catalytic activities of the photocatalysts were systematically studied through the catalytic reduction of hexavalent chromium (Cr⁶⁺) and oxidation of Bisphenol A (BPA) under visible light irradiation, while according to the degradation products determined by GC-MS, the catalytic degradation pathway of BPA was proposed. 4Au/g-C₃N₄/Co₃O₄ sample exhibits the most efficient catalytic activities, and the photocatalytic reduction and photocatalytic oxidation efficiencies can obtain 85.6% and 90.3%, respectively. The main reasons of the enhancing catalytic performance are the high absorption capability to visible light generated by localized surface plasmon resonance and the effective interface charge separation. Finally, we speculated that the Au/g-C₃N₄/Co₃O₄ sample followed Z-scheme charge transfer mechanism in this study, which is verified by the analysis of experiment and theoretical calculation results.