Photochemical preparation of the ternary composite CdS/Au/g-C3N4 with enhanced visible light photocatalytic performance and its microstructure

Abstract

A ternary composite photocatalyst CdS/Au/g-C₃N₄ was synthesized by a facile two-step photoreduction method. In this hybrid structure, CdS nanoparticles and CdS@Au core–shell nanoparticles are homogeneously deposited on the surface of g-C₃N₄ to produce two different structures CdS–g-C₃N₄ and CdS@Au–g-C₃N₄. The microstructure analysis results of the composition, chemical states, and optical properties of as-prepared ternary hybrid reveal that a strong interaction exists between CdS nanoparticles, CdS@Au nanoparticles and the g-C₃N₄ bulk. The ternary composite CdS/Au/g-C₃N₄ exhibits significantly enhanced photocatalytic activity for RhB degradation under visible light irradiation compared with the binary composites CdS/g-C₃N₄, Au/g-C₃N₄ and pure g-C₃N₄. Meanwhile, CdS/Au/g-C₃N₄ also demonstrates good photostability in the recycling test of RhB degradation. The active species in the photocatalytic reaction over CdS/Au/g-C₃N₄ are detected as O₂˙⁻ and h⁺. The superior photocatalytic performance of CdS/Au/g-C₃N₄ should be attributed to the enhanced separation efficiency of photogenerated electrons–holes induced by the formed heterojunctions CdS–g-C₃N₄ and Z-scheme structure CdS@Au–g-C₃N₄ where Au nanoparticles serve as electrons mediator.