The Application Of Composite Photocatalysts Containing Zr And Ti Based Coordination Polymer And CdS In The Photocatalytic Hydrogen Evolution

Since Fujishima and Honda first applied TiO2 to water splitting in 1972, numerous catalysts have been discovered for Photocatalytic hydrogen evolution. CdS was studied widely in this domain due to its visible light response and strong reduction capability of photogenerated electrons. Therefore, to further enhance its catalytic activity is the highlight of our research.It is a feasible way to improve photocatalytic performance of CdS that increasing the catalytic sites of CdS by embedding them on porous materials with large specific surface area.As a type of inorganic-organic hybrid porous material, coordination polymer could be the ideal host to support CdS due to its high porosity and large specific surface area. As a result, the composite photocatalyst that incorporating CdS with coordination polymer would show perfect activity in visible-light photocatalytic hydrogen generation. In this paper, the strategies we take to enhance the activity of CdS in hydrogen evolution are as follow:(1) the Zr based coordination polymer UiO-66 with high stability was chosen as the support and the S8 and CdCl2 were selected as precursors. To prepare the composite photocatalyst UiO-66/CdS by a photodepositon reaction under UV light to enhance the activity of CdS. Then the influence of photodeposition time on the hydrogen production efficiency of as-synthesized photocatalyst was studied (2) on the basis of UiO-66/CdS binary hybrid, the graphene was introduced to construct ternary hybrid consisting of UiO-66, CdS and graphene, thus enhancing the photocatalyic hydrogen production activity of CdS by both accelerating the transfer of its photogenerated electrons and increasing the surface catalytic sites. (3) By using MIL-125 to take the place of UiO-66 to construct the composite MIL-125/CdS, which is the advanced heterostructure of TiO2/CdS. The introduction of MIL-125 will enhance the activity of CdS in photocatalytic hydrogen evolution by both avoiding the agglomeration of CdS nanoparticles and separating the photogenerated electrons.The original results of this paper are as follows:(1) Using the unconventional preparing method-photodeposition strategy to synthesize the composite consisting of coordination polymer and CdS,and we firstly apply the composite prepared by the photodeposition method to the photocatalytic hydrogen evolution; (2) We successfully synthesize the ternary hybrid containing UiO-66, CdS and graphene, and this is the first approach that enhances the photocatalytic activity of CdS by both increasing the catalytic sites and suppress the recombination of charge carriers; (3) Constructing the advanced TiO2/CdS heterostructure-MIL-125/CdS to enhance the hydrogen evolution activity and to prove that MIL-125 can not only avoid the agglomeration of CdS nanoparticles, but also facilitate the separation of charge carriers.