The Construction Of Photocatalytic Materials Based On CdS,g-C₃N₄ And Zn_0.8Cd_0.2S And Their Hydrogen Production Properties Were Studied

In this paper,non-precious metal phosphides are introduced as promoters to slow down the efficiency of the electron-hole recombination of semiconductor catalysts,increase the active sites of photocatalytic hydrogen production of semiconductor materials,improve the ability of trapping H⁺and accelerate the rate of hole oxidation sacrificial reagent.Phosphide as a co-catalyst not only improves the photocatalytic hydrogen production activity,but also studies the process of electron transfer inside the semiconductor from the microscopic electronic point of view.The main work is as follows:1.Based on CdS semiconductor material and bimetallic phosphide WNi₄P₁₆as a promoter,a new composite material WNi₄P₁₆/CdS was successfully synthesized by hydrothermal and calcination methods to improve the photocatalytic hydrogen production activity of CdS.Under the condition of 10%lactic acid（Volume fraction）as the sacrificial reagent,an efficient and stable photocatalytic hydrogen production system was constructed.Through further test data,we found that the hydrogen production efficiency of WNi₄P₁₆/CdS composite material is as high as 878μmol in 4 hours when the WNi₄P₁₆precursor is 0.7 mmol equivalent,which is about 11.2 times higher than the hydrogen production of pure CdS and pure WNi4P16photocatalyst And 109.7 times.This clearly proves that the introduction of non-metallic phosphating WNi₄P₁₆can significantly enhance the performance of photocatalytic hydrogen production.In addition,we also proved our test results through XRD,SEM,XPS,ultraviolet-visible diffuse reflectance,electrochemical response,steady-state fluorescence and other characterizations,and explained the mechanism of WNi₄P₁₆/CdS composite materials.2.Synergistic composite material g-C₃N₄/Cu₃P/UiO-66 with uniform three-dimensional（3D）cubic structure distribution was synthesized by hydrothermal method and grinding.Larger spherical particles（UiO-66）are evenly distributed on the g-C₃N₄sheet-like nanomaterial.The specific surface area of CNCU-3 reaches an astonishing 1002.08（m²/g）,which is 23 times that of the base material g-C₃N₄.As a result,adding Cu₃P and MOFs can effectively improve charge transfer and separation,and increase the hydrogen production activity of the photocatalyst.The photocatalytic activity of g-C₃N₄/Cu₃P/UiO-66 ternary composite material is significantly better than monomer g-C₃N₄,binary g-C₃N₄/Cu₃P and g-C₃N₄/UiO-66,especially the introduction of UiO-66 hydrogen production Increased,the maximum hydrogen production reached 79μmol in five hours.In addition,XRD,SEM,TEM,PL,UV-vis,XPS proved that Cu₃P effectively conducts electrons to promote electron transfer,and UiO-66 provides a large specific surface area.The synergy of these factors plays a key role in the photocatalytic activity.3.Introduce CoP on the bimetallic sulfide Zn_0.8Cd_0.2S to construct a CoP/Zn_0.8Cd_0.2S synergistic system.Zn_0.8Cd_0.2S and CoP monomers were synthesized by hydrothermal method and calcination method respectively,and then subjected to strict and complicated grinding,and finally successfully synthesized the new composite photocatalyst material CoP/Zn_0.8Cd_0.2S.The synthesized new catalyst was tested for hydrogen production under 10%lactic acid reaction conditions.It was found that when the precursor of CoP was 0.5 mmol equivalent,the hydrogen production activity of the composite catalyst reached a maximum of 4 h 349μmol,which was higher than pure Zn_0.8Cd_0.2S It is twice as much.The characterization results of XRD,SEM and XPS showed that CoP was successfully loaded onto Zn_0.8Cd_0.2S and the morphology,crystal structure and composite valence state of the two composites were consistent with our previous investigations.Fluorescence steady-state spectroscopy and electrochemical tests showed that the composite material CoP/Zn_0.8Cd_0.2S successfully reduced the electron-hole recombination rate and accelerated the rate of electron transfer,comprehensively indicating that the new catalyst showed excellent photocatalytic hydrogen production activity.At the same time,based on the CoP/Zn_0.8Cd_0.2S.coordination system,the charge transfer mechanism and hydrogen production mechanism are proposed.