Photocatalytic Degradation of Rhodamine B on MOS₂ Microspheres Prepared by Sodium Dialkyldithiophosphate-Assisted Hydrothermal Synthesis

Abstract—

MoS₂ microspheres were synthesized via a facile hydrothermal method using (NH₄)₂MoO₄, H₂C₂O₄·2H₂O, and sodium dialkyldithiophosphate (NaDDP) as reactants. Herein, NaDDP plays a role of surfactant for the formation of the MoS₂ microspheres, unlike other different sulfur sources. The morphology and crystal structure of the MoS₂ microspheres were characterized using scanning electron microscope (SEM) and X-ray diffraction (XRD). The prepared MoS₂ microspheres were used as a catalyst for photocatalytic degradation of rhodamine B. The effect of the size of the MoS₂ microspheres on photocatalytic activity was investigated. For comparison, NaDDP was replaced by thiourea, thioacetamide and L-cysteine. The results indicate that the MoS₂ microspheres are spherical, and the diameter of the MoS₂ microsphere decreases with increasing concentration of oxalic acid in the reactants. The MoS₂ microspheres have hexagonal 2H-MoS₂ structure and preferentially grow along the (002) plane. In addition, it is found that when the concentration of oxalic acid is 0.075 mol/L, the best photocatalytic efficiency is 91.3% within irradiation time of 120 min and the reaction rate constant is 0.163 min^–1. The photocatalytic activity of MoS₂ synthesized from four sulfur sources can be arranged in the following order: NaDDP > thioacetamide > L-cysteine > thiourea.