Studies On Preparation Of Cd_xZn_1-XS And Its Photocatalytic Hydrogen Evolution From NaCl Saltwater Using Glucose As An Electron Donor

In this thesis, using biomass glucose as an electron donor, the photocatalytic hydrogen evolution over Pt/CdxZn1-xS from NaCl saltwater had been investigated. A possible mechanism was discussed. The optimum conditions of photocatalytic reaction also had been investigated. It is expected that with appropriate photocatalyst and reaction system, more efficient hydrogen evolution from saltwater can be achieved. Using glycol as an electron donor, the photocatalytic hydrogen evolution from seawater over Pt/TiO2 had been investigated. The reseach work is composed of three parts:In the first part, surface property of Cd0.5Zn0.5S in basic aqueous solution was characterized by X-ray photoelectron spectroscope (XPS). The surface S species at Cd0.5Zn0.5S under basic condition is substituted by O species. The surface adsorption performance of glucose and NaCl was characterized by adsorption experiment and electrophoretic analysis. Glucose is adsorbed on Cd0.5Zn0.5S via two modes. The effect of electrolyte NaCl on photocatalytic hydrogen evolution over Pt/Cd0.5Zn0.5S using glucose as an electron donor has been investigated under visible light irradiation. NaCl can promote markedly the photocatalytic hydrogen evolution, which is very important to practical application. The photocatalytic activity for hydrogen evolution from 3.0 mol L-1 NaCl saltwater increases by 77% compared to that from pure water. A possible mechanism was discussed.In the second part, the photocatalytic hydrogen evolution from NaCl saltwater over Pt/CdxZn1-xS catalysts with glucose as an electron donor had been studied. The results showed that, compared to that in pure water, the activity of photocatalytic hydrogen evolution over Pt/CdxZn1-xS promoted obviously in 2.0 mol L-1 NaCl saltwater system. The influence of the ratio of Zn/Cd, initial concentration of glucose, the mass of loading platinum on photocatalytic hydrogen evolution had been investigated. Experimental results showed that in the 2.0 mol L-1 NaCl system, Cd0.2Zn0.8S can significantly improve the efficiency of photocatalytic hydrogen generation. Both glucose and NaCl can significantly improve the photocatalytic activity. The optimal mass of loading platinum over Cd0.2 Zn0.8 S from 2.0 mol L-1 NaCl saltwater was only half of that from pure water. This should be very important to practical application for the reaction system of the seawater with glucose.In the last part, using glycol as an electron donor, the photocatalytic hydrogen evolution from seawater over Pt/TiO2 had been investigated. The factors which affect photocatalytic hydrogen evolution, such as irradiation time, initial concentrations of the glycol solution, pH value of the suspensions and the co-existing substances were studied. The results showed that glycol can not only improve the efficiency of photocatalytic hydrogen generation but also be decomposed effectively.