Studies On The Design And Preparation Of Zn-In-S Photocatalysts And Their Hydrogen Production Properties

Metal sulfides semiconductor photocatalyst is considered as an ideal photocatalyst material because of its strong light absorption ability and high photostability.However,due to the easy recombination of photogenerated carriers in photocatalysts,the photocatalytic hydrogen production efficiency is still low.Therefore,in order to improve the hydrogen production efficiency of metal sulfide photocatalyst,it is necessary to carry out reasonable design and regulation.In this paper,the photocatalyst with high visible light responsivity and high photocatalytic activity for hydrogen production were successfully prepared by supporting co-catalyst,doping transition metal ions and adjusting the element composition of the photocatalyst.The specific research contents and conclusions of this paper are as follows:（1）We used MoS₃ as co-catalyst and Zn₃In₂S₆ as photocatalyst to investigate the hydrogen production activity of MoS₃/Zn₃In₂S₆composite photocatalyst prepared by a simple one-step hydrothermal method,and confirmed the generation and loading of MoS₃by TEM and XPS characterization methods.The experiment of photocatalytic hydrogen production shows that the hydrogen production rate of MoS₃/Zn₃In₂S₆ composite photocatalyst is significantly higher than that of Zn3In₂S₆ photocatalyst.When the MoS₃loading is 1.2%,the hydrogen production rate of the photocatalyst reaches 32.1μmol h^-1mg^-1.It is 3.5 times higher than that of Zn₃In₂S₆ photocatalyst without supported MoS₃.The above results indicate that MoS₃ supported co-catalyst can effectively promote the separation and migration of photogenerated electrons and holes,and thus significantly improve the rate of photocatalytic hydrogen production.This work provides enlightenment for the exploration and research of MoS₃ as co-catalyst for hydrogen production.（2）Based on In₂S₃ QDS,Cu-In₂S₃,Zn-In-S,Cu-Zn-In-S QDS photocatalysts with different element content and composition were successfully prepared by doping transition metal ions Zn and/or Cu.The conduction band potential and valence band potential of In₂S₃QDS can be controlled successfully by adjusting the type and amount of doped Cu or Zn.It was found that doping Cu could significantly increase the valence band potential of the photocatalyst,reduce the band gap of the photocatalyst,and enhance the absorption of visible light.The doping of Zn can increase the band conduction potential of photocatalyst and enhance the driving force of hydrogen production reduction reaction.Therefore,photocatalysts with high visible light responsiveness and high hydrogen reduction driving force can be prepared by adjusting the doping amount of Cu and Zn.Finally,the prepared Cu_0.4-Zn In₂S₄ QDS exhibited excellent photocatalytic hydrogen production activity.Under visible light irradiation and the presence of Ni²⁺co-catalyst,the rate of hydrogen production was 144.4μmol h^-1 mg^-1,480 times that of In₂S₃QDS（3）We used Ag _X-Zn In₂S₄ QDS as photocatalyst,and successfully prepared MoS₂/Ag _X-Zn In₂S₄ composite photocatalyst in order to improve the photocatalytic hydrogen production efficiency.In this work,we explored the effects of MoS₂ cocatalyst loaded and transition metal Ag⁺doped on the enhancement of hydrogen production activity of photocatalyst.The light absorption performance of the composite photocatalyst,the separation and migration characteristics of the photogenerated carriers were characterized.It was found that doping Ag could reduce the band gap of the photocatalyst and increase the response of the photocatalyst to visible light.After loading MoS₂,the photogenerated electrons are promoted to migrate from Ag_0.2-Zn In₂S₄ to MoS₂,and the utilization of photogenerated electron-hole is improved.The hydrogen production experiment showed that the hydrogen production of 0.8%MoS₂/Ag_0.2-Zn In₂S₄ composite photocatalyst reached 1557.7μmol for 8h under visible light irradiation,which was 305 times that of Ag_0.2-Zn In₂S₄ QDS.