Study On The Photocatalytic Degradation Performance Of Transition Metal Phosphides

The sewage treatment is a major problem needs to be solved urgently in human society.As a relatively safe,environmentally friendly and cost-controllable solution,photocatalytic oxidation technology uses clean and abundant solar energy to accelerate the decomposition of pollutants by a heterogeneous reaction.Therefore,researchers pay attention to the photocatalytic oxidation technology achieve in the field of sewage purification.This thesis took transition metal phosphide(TMP)as the research object and successfully prepared hollow tubular cobalt phosphide(CoP)nanomaterials,CoP/MoS2 semiconductor heterojunction nanocomposites and carbon hybrid ultra-thin layer MoP@C nanomaterials,and studied the photocatalytic degradation activity of the above-mentioned materials on methylene blue(MB)and tetracycline(TC)pollutants under visible light.The main research contents are as follows:1.The precursor of cobalt basic carbonate(Co(CO3)0.5OH·0.11H2O)prepared with different molar ratios of cobalt nitrate and urea was annealed to prepare three kinds of tubular CoP nanomaterials successfully.We studied the photocatalytic degradation performance and catalytic mechanism of CoP on MB organic dyes under simulated visible light.The photocatalytic activity of the samples were analyzed by ultraviolet-visible diffuse reflectance spectroscopy,photoluminescence spectroscopy and photocurrent response tests.The results showed that when the molar ratio of cobalt nitrate and urea was 1:4,the obtained tubular CoP had the highest photocatalytic activity.After 4 hours of degradation reaction,the removal rate of MB reached 79.3%.In addition,the mechanism of MB degradation by CoP under simulated visible light was clarified through active radical quenching experiment and ESR spectrum analysis.2.In order to improve the catalytic activity of CoP in the degradation of organic pollutants under visible light,the CoP/MoS2 semiconductor heterojunction nanocomposite material was designed and prepared.MoS2 nanosheets are uniformly distributed on the surface of tubular CoP.The photocatalytic degradation performance and catalytic mechanism of CoP/MoS2 for MB and TC organic pollutants under visible light environment have been studied.The results showed that the removal rate of MB reached 87%after 2 hours degradation reaction.The TC degradation results were qualitatively and quantitatively analyzed using infrared spectroscopy and ultraviolet-visible diffuse reflectance spectroscopy.CoP/MoS2 decomposed TC wastewater adsorbed on CoP/MoS2 with a removal rate of 64.1%under 4 hours visible light,The contaminants on the surface of MoS2 were basically decomposed.The results of photoluminescence spectroscopy and photocurrent response test showed that CoP and MoS2 synergistically increase the electron-hole separation rate of the photocatalyst under simulated visible light and the transmission speed of photo-generated charge pairs,in order to optimize the photocatalytic activity of CoP/MoS2.In addition,the active radical quenching experiment and ESR spectrum analysis further clarified the possible mechanism of the CoP/MoS2 semiconductor heterojunction nanocomposite improving the degradation performance of MB greatly under simulated visible light.3.The ultra-thin layer MoP@C nanomaterials were designed and prepared,and the photocatalytic degradation performance and mechanism with different amounts of MoP@C were studied.The photocatalytic activity of the samples was analyzed by ultraviolet-visible diffuse reflectance spectroscopy,photoluminescence spectroscopy,and photocurrent response tests.The results showed that the removal rate was the highest,reaching 70.7%,when the amount of MoP@C adding 5mg to MB(20 mg/L,100 mL)after 4 hours of light reaction.In addition,through active radical quenching experiments and ESR spectroscopy analysis,the possible mechanism of MoP@C degradation of MB under simulated visible light was clarified.