Design,Synthesis And Catalytic Performance Of Mo-Based Photocatalysts

Mo-based compounds are a very common material in the field of catalysis.For example,Mo₂C can be used as a catalyst for the reaction of alkane isomerization,unsaturated hydrocarbon hydrogenation,hydrodesulfurization and denitrification;MoS₂ is a traditional photocatalyst,which is widely used in the field of visible light catalytic degradation.At the same time,MoO₃ is also a common semiconductor photocatalytic material with ultraviolet light response.After extensive literature research and experimental exploration,our research group proposed the use of molybdenum carbide to reduce the use of non-renewable energy sources such as precious metals in the field of photocatalysts.We found that molybdenum carbide has a significant role in promoting the visible hydrogen production performance of cadmium sulfide.Further verifying the role of molybdenum carbide in photocatalyst system,we designed and synthesized Mo2C/MoO3 photocatalyst.The experimental results show that Mo₂C/MoO₃ photocatalyst has Pt/MoO₃?3%mass fraction?visible light degradation organic pollutants.Efficiency,after XRD,XPS,PL,IMP,IT,DRS and other characterization methods,we found that Mo₂C plays a role similar to Pt in the system.Mo₂C can effectively improve the visible light responsiveness of MoO₃ and expand the visible light absorption of MoO₃.The interval can greatly improve the photo-induced charge hole separation rate of MoO₃,and further improve the efficiency of MoO₃ for catalytic degradation of methyl orange and reduction of Cr?VI?under visible light.At the same time,we also carried out experimental research on the catalytic activity of MoS₂ morphology.The specific research work is as follows:?1?A simple impregnation-calcination strategy was used to synthesize Mo₂C modified MoO₃?Mo₂C/MoO₃?catalyst and used in visible light degradation of methyl orange?MO?.Under visible light??>400nm?irradiation,the apparent rate constant of photocatalytic degradation of MO by Mo₂C/MoO₃ is k=0.0171min^-1,which is 4.59 and67.38 times of Pt/MoO₃ and MoO₃,respectively.Studies on the photocatalytic mechanism of Mo₂C/MoO₃ show that O₂^-plays a major role in MO degradation.The addition of Mo2C not only enhances the photo-response range of MoO3,but also increases the photogenerated electron-hole pair separation rate of molybdenum oxide and enhances the visible light reactivity of MoO₃.?2?A novel CdS/Pt/Mo₂C heterostructure photocatalyst was designed and synthesized.The synthesis route is:using the photoreduction deposition method to compact the nano-sized particles made of Pt into CdS/Mo₂C,thereby preparing a photocatalyst with high reactivity.Ultraviolet-visible spectroscopy and photoelectrochemical impedance analysis show that Mo₂C enhances the light absorption of CdS in the ultraviolet-visible region and improves the separation of CdS photoexcited electron-hole pairs.At the same time,Pt nanoparticles act as a cocatalyst that promotes transient photocurrent response.The H₂ experimental results show that the CdS/Pt/Mo2C heterojunction exhibits excellent H2 activity under visible light conditions,and its H₂ efficiency reaches 1828.82?mol·h-1·g-1,which are CdS and CdS/Mo₂C,respectively.8.5 and 16.2 times under the same reaction conditions.In addition,the CdS/Pt/Mo₂C heterojunction photocatalyst has a quantum yield?AQY?of9.39%when exposed to 400 nm excitation light.?3?A glycerol-molybdenum?MoG?precursor with uniform spherical morphology was prepared by solvothermal reaction,and the materials?ammonium molybdate,molybdic acid,acetylacetonate molybdenum?and reaction solvent?water and isopropanol?were changed.Proportion)Different sizes of glycerol molybdenum were obtained and a general rule was obtained:the morphology of MoG can be adjusted by the proportion of water in the mixed solvent.Generally,as the water content of the solvent decreases,the overall size of the MoG becomes larger and relatively less uniform.Then,the MoS₂ obtained after the vulcanization step has the same morphology and size as MoG.The H₂ experiment shows that the MoS₂ morphology has a direct influence on the photocatalytic activity.