Preparation And Photocatalytic Properties Of Molybdenum Disulfide Nanocomposites

Photocatalytic technology has potential application value in environmental treatment and energy supply,so it is of great significance to produce stable and efficient photocatalytic materials.TiO₂,as traditional photocatalyst,has become the most widely used photocatalyst because of its advantages of low cost,non toxicity and stability.However,TiO₂ can only absorb ultraviolet light and the light energy utilization rate is low,which limits its application.In order to solve this problem,MoS₂,a new semiconductor material with visible light response,was used as the research object in this paper.MoS₂ powder was prepared by low-cost hydrothermal method,and the photocatalytic performance of MoS₂ was studied.In order to further improve the photocatalytic performance of MoS₂,ZnO/MoS₂ composite was prepared by composite modification of MoS₂,and the photocatalytic performance of the composite was tested.With sodium molybdate?Na₂MoO₄·2H₂O?as molybdenum source and thiourea?CS?NH₂?₂?as sulfur source,spheroidal nano-MoS₂ with high specific surface area was prepared by mild hydrothermal method.The structure and morphology of nanometer MoS₂were investigated by XRD,SEM,BET and UV-vis methods.By changing the Mo/S ratio,water thermal response time,thermal water temperature,the precursor solution pH,surfactant and other process conditions,thechange ruleof structure and morphology of the nanostructured MoS₂ was discussed,and the growth mechanism of the nanometer MoS₂ was revealed.The results showed that nanometer MoS₂ with flower-like microsphere structure could be prepared when the reaction temperature was 220?,the reaction time was 24h,the pH of the precursor solution was 1.5,the molybdenum sulfur atomic ratio was 1:5,and CTAB was using as the surfactant.The specific surface area of nanometer MoS₂ prepared under optimized process parameters was 89.72m²/g.Selecting the optimum nanometer MoS₂ powdersas the study object,using cationic dye?Rhodamine B,RhB;Methylene blue,MB?and anionic dyes?Methyl orange,MO?,as well as the RhB-MO,the MB-MO binary mixture as the probe molecule,catalytic effect of the quantity of catalyst,initial concentration of pollutants,the solution of the initial pH on the MoS₂ powders was investigated.The results show that the nanostructured MoS₂ had good visible light catalytic ability.When the catalyst quantity was 0.05g,the MoS₂ powders with lower initial concentration?10mg/L,20mg/L?and weak acid environment?pH=5⁷?showed higher catalytic properties.In a single pollutant solution,the degradation rates of RhB,MB and MO by MoS₂ powder were 87.71%,85.70%and 84.87%,respectively.In RhB-MO mixture,the highest degradation rates of RhB and MO were 71.30%and 84.68%,respectively.In MB-MO mixture,the highest degradation rates of MB and MO were 84.13%and 76.80%,respectively.Secondly,the stability of nano-MoS₂ powder was investigated.The results showed that nano-MoS₂ powder still had good photocatalytic performance after 5 cycles,and its degradation rate of RhB was maintained at about 85%.Finally,the catalytic degradation mechanism of nano-MoS₂ was analyzed.Taking zinc chloride?ZnCl₂?and sodium hydroxide?NaOH?as zinc sources,ZnO nano particles were grown on MoS₂ nano sheet by hydrothermal method,and ZnO/MoS₂ composite was prepared.The ZnO/MoS₂ composite was characterized by XRD and SEM under different mass ratio of MoS₂ and ZnCl₂,and the composite was tested under different mass ratio of MoS₂ and ZnCl₂.The results show that the photocatalytic degradation rate of RhB is 95.45%and the specific surface area is 109.9m²/g when the composite content of ZnO/MoS₂ is 20%.Finally,the possible photocatalytic mechanism of ZnO/MoS₂ composite was discussed.