Synthesis of Z-scheme Mn-CdS/MoS2/TiO2 ternary photocatalysts for high-efficiency sunlight-driven photocatalysis

Abstract

The exploration of highly efficient visible-light-driven photocatalysts for dye degradation has received great concerns in wastewater treatment. Here, molybdenum disulfide (MoS2) and cadmium sulfide–manganese (CdS-Mn) were sequentially assembled onto titanium dioxide (TiO2) nanotube by a simple hydrothermal method coupled with successive ionic layer adsorption and reaction. A zinc sulfide (ZnS) layer was introduced as a potential barrier for performance improvement; the resultant material exhibits prominent visible-light-induced photocatalytic activity in degrading methyl orange (MO) and 9-anthracenecarboxylic acids, which is 3.16-fold, 2.00-fold, and 1.69-fold or 2.86-fold, 1.56-fold, and 1.47-fold of TiO2, MoS2/TiO2, and CdS-Mn/TiO2 systems, respectively. Furthermore, the synthesized ZnS/CdS-Mn/MoS2/TiO2 composite also possesses a high hydrogen production rate of 408.27 mmol/cm2/h out of water under visible light illumination, which is about 30.08 times greater than that of pure TiO2 and 5.18-fold and 2.52-fold of MoS2/TiO2 and CdS-Mn/TiO2, respectively. The enhanced photocatalyst performances are mainly attributed to the synergetic effects of CdS-Mn, MoS2, and TiO2, forming a Z-scheme system in the CdS-Mn/MoS2/TiO2 electrode, which not only accelerates the interfacial charge transfer efficiency but also preserves the strong redox ability of the photogenerated electrons and holes. In addition, the prepared photoelectrode is highly stable and completely recyclable over hydrogen evolution reaction and organic degradation.