Deposition of CdS and ZnS directly on rGO via. an emulsion-solvothermal method for excellent photocatalytic activity and stability

Abstract

Graphene was often employed as electron mediator between semiconductors in the heterogeneous materials to improve electron transfer and therefore enhance photocatalytic performance. Little reported synthesis method can guarantee the deposition of two different semiconductors directly on graphene. In this work, an emulsion-solvothermal method employing graphene oxide (GO) as surfactant was proposed to prepare CdS/reduced graphene oxide (rGO)/ZnS composites for accomplishing the direct contact of CdS and ZnS with rGO. The optimal composite CG0.5Z prepared via. emulsion-solvothermal method can produce H2O2 with the remarkable efficiency of 24.93 mM g−1 h−1 under visible light, and rapidly decompose tetracycline and RhB with the removal rate of 80.3% and 87.4%, respectively, after only 10 min irradiation, exhibiting superior photocatalytic activity to the material prepared via. conventional method. CG0.5Z also exhibited out-standing photocatalytic ability under real sunlight irradiation. The recycling experiments proved the excellent stability of the obtained ternary composite. The photoluminescence measurements, the time-resolved photoluminescence decay curves and Mott-Schottky plots further confirmed the more efficient electron-hole spatial separation and transfer in composite prepared through emulsion-solvothermal route, proving the emulsion-solvothermal synthesis is a better way to construct the rGO bridge between semiconductors. The possible degradation reaction pathways were also deduced based on the detected intermediate products.