Improving Effect And Mechanism Of Ni₁₂P₅ On The Photocatalytic Activity Of Zn_0.5Cd_0.5S For H₂ Generation

Photocatalytic H₂ production from water using sunlight is an attractive process to solve the global energy and environmental problems.Compared with the traditional H₂-generation strategy,photocatalytic splitting of water into H₂ by semiconductor photocatalysts has potential advantages,sucha as clean and highly efficient.Therefore,H₂ production by water splitting has important scientific research value.In recent years,solid solution Zn_xCd_1-xS formed by CdS and wide-band gap ZnS semiconductor has attracted wide attention.In this paper,a novel Ni₁₂P₅/Zn_0.5Cd_0.5S photocatalyst was constructed with the solid solution Zn_0.5Cd_0.5S as substrate and phosphide Ni₁₂P₅ adhered to its surface as a new the cocatalyst.On this basis of Ni₁₂P₅/Zn_0.5Cd_0.5S,secondary modification was carried out,and the photocatalytic activity of H₂ production was studied.?1?One dimension Zn_0.5Cd_0.5S photocatalyst was firstly prepared by mixed solvent-thermal method.Then a small amount of Ni₁₂P₅ was loaded on the suface of Zn_0.5Cd_0.5S by hydrothermal method.The structure,morphology,composition,light absorption and photoelectric performances of the photocatalyst were systematically studied using XPS,XRD,DRS,SEM,HRTEM,BET and electrochemical testing.Under visible light??>420 nm?,the photocatalytic water splitting H₂ production rate of Zn_0.5Cd_0.5S reached 10.4 mmol·g^-1·h^-11 using a mixed solution of Na₂S and Na₂SO₃as sacrificial agent.After Ni₁₂P₅ was loaded,the H₂ production rate of Ni₁₂P₅/Zn_0.5Cd_0.5S reached 29.26 mmol·g^-1·h^-1,2.91 times than that of the Zn_0.5Cd_0.5S.The above result indicates that Ni₁₂P₅ is an excellent cocatalyst.?2?On the basis of Ni₁₂P₅/Zn_0.5Cd_0.5S,a certain amount of elemental?-S was loaded ont the surface of Ni₁₂P₅/Zn_0.5Cd_0.5S though solvent evaporation-deposition-precipitation method.The formed S/Ni₁₂P₅/Zn_0.5Cd_0.5S photocatalyst showed stronger photocatalytic H₂ production performance.Under visible light??>420 nm?,the photocatalytic water splitting H₂ production rate of S/Ni₁₂P₅/Zn_0.5Cd_0.5S was 52.55mmol·g^-1·h^-11 using a mixed solution of Na₂S and Na₂SO₃ as sacrificial agent.When the loadling amount of?-S was 15%,an increase of 1.65 times was presented in comparision with that of Ni₁₂P₅/Zn_0.5Cd_0.5S.The result of potogenerated carrier separation indicates that S/Ni₁₂P₅/Zn_0.5Cd_0.5S might involve a Z-scheme electron transport mechanism,in which Ni₁₂P₅ acted as an important electron transfer medium.