Study On Preparation And Water Treatment Application Performance Of Molybdenum Selenide And Its Composites

In recent years,environmental functional materials,especially photocatalytic materials,have been a hot topic in the field of environmental research.MoSe₂,which belongs to transition metal chalcogenide,has a graphene-like layered structure and has a good application prospect in the fields of catalysis and adsorption.However,due to its weak molecular binding force,there are many difficulties in preparation.In this paper,MoSe₂ and MoSe₂/TiO₂ composites were prepared by hydrothermal method.MoSe₂/Ag₃PO₄ composites were prepared by in-situ deposition method.The prepared materials were characterized by various characterization methods.The adsorption of Rhodamine B,methyl orange and methylene blue by MoSe₂ and the photocatalytic degradation of Rhodamine B by MoSe₂/TiO₂composite and MoSe₂/Ag₃PO₄ composite were studied.?1?A flower-like MoSe₂ was synthesized at 220°C with sodium molybdate and selenium powder as raw materials,sodium borohydride as a reducing agent,and a mixed solution of deionized water and ethanol in a volume ratio of 1:1 as a solvent.XRD,SEM,TEM,BET and other characterization methods indicate that the prepared MoSe₂ is flower-like and pure without impurities and has a hexagonal structure.Adsorption experiments show that MoSe₂ has a good removal rate for dyes.The influence of the initial concentration of the dye,the pH of the solution and the temperature of the solution on the adsorption performance was investigated with RhB as the target contaminant.The results show that the increase of the initial concentration of dye,pH and temperature can increase the adsorption capacity.Adsorption thermodynamic studies show that the adsorption process is more in line with the Langmuir model and is a monolayer adsorption.The R_L value shows that the adsorption process is very easy.The study of adsorption kinetics shows that the adsorption process is more in line with the pseudo-first-order kinetic equations,and the physical adsorption is the main one.Cycle experiments show that MoSe₂ still has good adsorption performance after three cycles.Photocatalytic experiments show that MoSe₂ has almost no photocatalytic properties?2?The MoSe₂/TiO₂ composites were synthesized by hydrothermal method and the composites were characterized by XRD,SEM,UV-vis and XPS.The photocatalytic activity of the complexes on Rhodamine B solution was discussed.The decolorization rate of 100mL and 10 mg/L rhodamine B solution reached 92%at 90 min when the catalyst dosage was 10 mg under visible light irradiation.The photocatalytic activity of the composite was significantly higher than that of TiO₂,achieving visible light response.The influence of initial concentration of dye,the pH and the temperature of the solution on the photocatalytic performance was investigated.The results showed that the increase of the initial concentration of dye led to the decrease of the light transmission of the solution,which reduced the photocatalytic performance,and the increase of pH and temperature could increase the Photocatalytic rate.The investigation of the photocatalytic mechanism shows that the main active species produced in the photocatalytic process are·OH and holes.The cyclic experiment shows that the composite catalyst still has good photocatalytic efficiency after three cycles.?3?The MoSe₂ was synthesized by hydrothermal method.The composite photocatalysts were prepared by in-situ deposition method using silver nitrate and disodium hydrogen phosphate as raw materials.The composites were characterized by XRD,SEM,XPS and UV-vis.The photocatalytic activity of the complex on Rhodamine B solution was investigated and the decolorization rate of 100 mL and 10 mg/L rhodamine B solution reached 92%at 60 min when the catalyst dosage was 10 mg under visible light irradiation.The photocatalytic ability of the complex is higher than that of Ag₃PO₄.The influence of initial concentration of dye,pH and the temperature of the solution on the photocatalytic performance was investigated and the results showed that the increase of the initial concentration of dye led to the decrease of the light transmission of the solution,which reduced the photocatalytic performance,the pH and temperature increase can increase the photocatalytic rate.The experiments on the photocatalytic mechanism show that the main active species produced by this photocatalyst during the photocatalysis process are the holes and O₂^-.Cycling experiments showed that after the addition of MoSe₂,the recycling capacity of the catalyst was enhanced.The above studies indicate that MoSe₂ prepared by the hydrothermal method is not a monolayer structure,but is an indirect bandgap semiconductor and has almost no photocatalytic performance,but the composite with TiO₂ and Ag₃PO₄ can improve the utilization of visible light by the composite and reduce the photoelectron.The coincidence rate with the holes,so that the composite material has better photocatalytic performance than the monomer material.