Synthesis And Study Of Zn_0.5Cd_0.5S-based Nanocomposite For Visible-light-drivien Photocatalytic Hydrogen Evolution From Spliting Water

Compared with the traditional hydrogen production process with high energy consumption,disintegrating water to produce hydrogen through semiconductor photocatalytic technology is one of the green and ideal method for the preparation of hydrogen.The advancement of photocatalytic technology has promoted the rapid development of the hydrogen energy industry,and alleviated the energy crisis and environmental problems.However,the rapid recombination rate of photogenerated carriers limits the photocatalytic hydrogen production activity,and the development of a high-activity visible-light-driven photocatalytic material system that spliting water to produce hydrogen has become a research focus.Compared with Cd S,Zn_0.5Cd_0.5S solid solution has excellent stability,light corrosion resistance and photocatalytic activity.In this paper,Zn_0.5Cd_0.5S nanoparticles are anchored on nickel-based or cobalt-based two-dimensional nanosheets to obtain two-dimensional/zero-dimensional nanocomposites.The loading of two-dimensional nanosheets can accelerate the separation and transport of photogenerated electrons and holes,thus improving the photocatalytic hydrogen production performance.The main research contents are as follows:(1)Preparation of Ni(OH)₂/Zn_0.5Cd_0.5S nanocomposite with two-dimensional/zero-dimensional construct and its the visible-light-driven pohotocatalytic production hydrogen activity from splitting water.Ni(OH)₂ nanosheets and Zn_0.5Cd_0.5S nanoparticles were synthesized by solvothermal method,and Zn_0.5Cd_0.5S was loaded on Ni(OH)₂ by liquid phase method to prepare two-dimensional/zero-dimensional Ni(OH)₂/Zn_0.5Cd_0.5S nanocomposite.The photocatalytic hydrogen production rate of 7%Ni(OH)₂/Zn_0.5Cd_0.5S reached 6870?mol·h^-1·g^-1,which is 43 times and 8 times higher than that of Zn_0.5Cd_0.5S and 3%Pt/Zn_0.5Cd_0.5S respectively.And it still has excellent stability after a 20-hour cycle test.Based on the photoelectrochemical properties and time-resolved fluorescence spectroscopy test analysis,it is proposed that Ni(OH)₂ in the composite material as a co-catalyst provides a loading platform and active sites,and at the same time can efficiently separate and migrate the photogenerated electrons and holes in Zn_0.5Cd_0.5S,reduce the hydrogen production overpotential,and thus accelerate the hydrogen release rate under light irradiation.(2)Preparation of cobalt-based nanosheets/Zn_0.5Cd_0.5S with two-dimensional/zero-dimensional construct nanocomposites and its the visible-light-driven pohotocatalytic production hydrogen activity from splitting water?The solvothermal method was used to synthesize Co(OH)₂ nanosheets and Zn_0.5Cd_0.5S nanoparticles,The Co(OH)₂ nanosheets were used as precursors,and they were calcined in a mixture of hydrogen and argon and air to produce Co nanosheets and Co₃O₄ nanosheets.Two dimensional/zero-dimensional Co(OH)₂/Zn_0.5Cd_0.5S,Co/Zn_0.5Cd_0.5S and Co₃O₄/Zn_0.5Cd_0.5S nanocomposites with different nanosheet ratios were prepared by component modulation.The results of the photolytic hydrogenation performance tests showed that 7%Co(OH)₂/Zn_0.5Cd_0.5S,9%Co/Zn_0.5Cd_0.5S and 9%Co₃O₄/Zn_0.5Cd_0.5S had the highest visible-light-driven photodcatalytic rate of hydrogen production from disintegrating water,which were 8 times,9.2 times and 12 times higher than that of Zn_0.5Cd_0.5S,respectively,and all kept excellent cycling stability in the 12-hour cycle hydrogen evolution test.The analytical results of electrochemical properties,UV-Vis absorption spectroscopy and steady-state fluorescence spectroscopy tests were used to elucidate the rapid separation and transfer of photogenerated electrons and holes in cobalt-based nanosheet/Zn_0.5Cd_0.5S nanocomposites.Among the three composite materials,Co₃O₄/Zn_0.5Cd_0.5S has the best photocatalytic hydrogen production ability,mainly due to the rapid directional movement of photogenerated electrons and holes under the action of the built-in electric field of the p-n junction in the composite material,So as to obtain excellent performance of visible-light-driven photocatalytic hydrogen evolution from splitting water...