Study On The Preparation And Photocatalytic Properties Of Surface Dispersed Heterojunctions

At present,photocatalytic materials generally have the problems of weak visible light response ability and high photogenerated carrier recombination rate.Therefore,improving the photocatalytic performance of semiconductor materials has become a hotspot of current research.Among them,the construction of heterojunctions is one of the effective means,especially the surface dispersed heterojunction structure,which has a large area of effective contact interface and a relatively high efficiency of photogenerated charge separation,usually showing good photocatalytic performance.Therefore,this paper constructed several surface dispersed heterojunctions materials with different dimensions,including CdS/（WO₃&WS₂）one-dimensional nanorods heterojunctions,Fe₂O₃/Y₂O₃@TNS two-dimensional nanorods heterojunctions and CdS/MoS₂ three-dimensional nanophiles heterojunctions,and systematically studied their surface morphology,microstructure,photoelectric characteristics and visible light catalytic performance.1.The Fe₂O₃/Y₂O₃@TNS heterojunctions were prepared by one-pot hydrothermal method.During the hydrothermal process,P25 nanoparticles（3D）were transformed into TNS nanoparticles（2D）.The visible light absorption capacity of the composite system was significantly improved.The photocurrent results show that the photocurrent intensity of Fe₂O₃/Y₂O₃@TNS was about 7 times that of P25 and 5times that of TNS,and 2.5 times and 1.8 times that of Fe₂O₃@TNS and Y₂O₃@TNS,respectively.Fe₂O₃/Y₂O₃@TNS showed excellent photocatalytic activity of visible light.The photocatalytic efficiency of Rh B and MO was 8.8 times and 16.2 times that of P25,respectively.The photodegradation rate of K₂Cr₂O₇ solution was 6.6 times that of pure P25 and 1.4 times that of Fe₂O₃@TNS or Y₂O₃@TNS.In addition,Fe₂O₃/Y₂O₃@TNS also showed strong adsorption capacity and good photocatalytic degradation and regeneration performance for CV solution with high chroma.2.Three dimensional CdS/（WO₃&WS₂）heterojunction was successfully synthesized by loading CdS nanoparticles on one-dimensional WO₃&WS₂ nanorods with a two-step method.The content of CdS has an important influence on the performance of the catalyst.When the mass ratio of CdS to WO₃&WS₂ was 40 wt%,the sample showed the best photoelectric chemical performance and hydrogen evolution performance,and the photocurrent intensity（13.3μA/cm²）and hydrogen production(754.2μmol g^-1h^-1)are 11.4 and 6 times that of WO₃&WS₂ nanords,respectively.DRS,PL,photocurrent and electrochemical results showed that CdS/（WO₃&WS₂）heterojunctions significantly increased the visible light absorption capacity,significantly reduced the recombination rate of electron-hole pairs,and had good reproducibility and stability.3.CdS/MoS₂ nanometer flower heterostructions were synthesized by hydrothermal method.The microstructure and photoelectric properties of CdS/MoS₂were studied by HRTEM,XRD,Raman,BET,electrochemical methods.Compared with pure MoS₂,the prepared CdS/MoS₂ heterojunction composites show better photocatalytic hydrogen production performance.The different mass ratios of CdS and MoS₂ also had a significant impact on the photocatalytic hydrogen production performance,among which 40 wt%-CdS/MoS₂ composite samples showed the best photocatalytic hydrogen production performance.Na₂S/Na₂SO₃ and glucose were used as sacrificial agents respectively.It was found that the hydrogen production performance of glucose as sacrificial agent was better than that of Na₂S/Na₂SO₃ as sacrificial agent,indicating that CdS/MoS₂ had good application potential in photocatalytic decomposition of biomass aqueous solution to produce hydrogen.