Characterization And Photocatalytic Activity For Hydrogen Evolution Of Ternary Metal Sulfides Prepared With Hydrothermal Method

With the development of economics, the world is faced with energy crisis. It has bright prospect to produce hydrogen by splitting water over semiconductor catalysts under the irradiation of visible light, which combine solar energy and hydrogen energy. As the core of photocatalytic hydrogen production, there are many problems should be settled including the improvement of solar energy use efficiency and photocatalytic activity. ZnIn2S4, CdIn2S4ternary metal sulfides phtocatalysts and composite catalysts have been synthesized by surfactant assisted hydrothermal method and characterized by characterized by X-ray diffraction (XRD), UV-visible absorption spectra (UV-vis) scanning electron microscopy (FESEM), N2adsorption desorption analysis, X-ray photoelectron spectroscopy (XPS). Photocatalytic H2production with various photocatalysts was evaluated by decomposition of Na2S and mixed aqueous under the radiation of simulated visible light. The mechanism of self-assemble of the nanoparticles assisted by surfactant was discussed.Porous ZnIn2S4photocatalysts possessed hexagonal layered structure was prepared by hydrothermal synthesis. Addition of CPB was good for the self-assemble of nanoparticle. The absorption edge is around500nm. The optimized parameters for the preparation were as follow:pH value of the reaction mixture was2.0, amount of CPB was0.21g, reaction temperature was140℃and reaction time was12h. The ZnIn2S4photocatalyst prepared with the optimized parameters shown the highest photocatalytic activity for hydrogen production and the average rate for hydrogen production was1544.8μmol/(h·g) under radiation of visible light. Porous ZnIn2S4photocatalysts modified by doping with transition metal ions Cr3+、Mn2+、Cu2+were prepared by hydrothermal method assisted by surfactant. Absorption edge of dopped ZnIn2S4shifted to long wave. Self-assemble of nano particles were destroyed by the introduction of transition metal ions. The photocatalytic activities of ZnIn2S4were improved by doping and Mn2+-doped catalyst shown the highest H2evolution rate of3286.4μmol/(h·g)Porous CdIn2S4photocatalysts with microsphere morphology possessed cubic phase were prepared by surfactant assisted hydrothermal method. It was found that SDS could promot the self-assemble of the nanoparticls and benefit to the formation of porous microsphere. The optimized preparation parameters were as follow:the amount of SDS was0.57g, water acted as reaction solvent, hydrothermal temperature was160℃, reaction time was12h. The rate of H2evolution of CdIn2S4modified by Mn2+doping was1296.2μmol/(h·g), which was higher than undoped catalysts.Cdx/Zn1-xIn2S4composite catalysts have been prepared by hydrothermal method without surfactants. Solid solution of CdIn2S4and ZnIn2S4was not detected. The absorption edge shifted to red and the band gap energy decreased from2.29eV to2.15eV with the increasement of doping amount. Photocatalytic activity of Cdx/Zn1-xIn2S4catalysts increase firstly and then decrease with the increasement of x value. Cd0.3/Zn0.7In2S4composite catalysts shown the highest photocatalytic activity of590μmol/(h·g). Cd0.3/Zn0.7In2S4photocatalyst doped with Ni2+has been prepared by hydrothermal method. The absorption edge shifted to blue and the efficiency of charge separation was improved. The photocatalytic activity of the The photocatalytic activity of the Ni2+doping Cd0.3/Zn0.7In2S4increased and the H2evolution rates reached3319μmol/(h·g) over Ni (5%)-Cd0.3/Zn0.7In2S4, which were higher than undoped composite catalysts.The H2evolution rate of the porous catalysts were higher than nomal MIn2S4(M=Zn, Cd). The absorption edge red-shif after modification by doping with transition metal ions, which means the band gap narrow down. The photocatalytic activity for H2evolution increased under radiation of visible light. The surface area of doped catalysts decreased compared with undoped catalysts. The photocatalytic activity for H2evolution of ZnIn2S4was higher than CdIn2S4. The photocatalytic activity for H2production of Cdx/Zn1-xIn2S4composite catalysts was improved greatly by doping with Ni2-...