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

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.