Photocatalytic Hydrogen Production Using Pollutants As Electron Donor Over Cd_0.5Zn_0.5S Solid Solution

In this thesis, using pollutants from water as electron donors, the photocatalytic hydrogen evolution and decomposition of the pollutants over Cd_0.5Zn_0.5S solid solution have been investigated. The research work is composed of two parts.In the first part, We successfully synthesized the non-noble metal NiS/Cd_0.5Zn_0.5S photocatalyst. Using triethanolamine?TEOA?, sodium sulfide?Na2S?and a mixed triethanolamine + sodiumsulfide?TEOA+Na2S? as electron donors, the photocatalytic hydrogen evolution over NiS/Cd_0.5Zn_0.5S under visible light irradiation was investigated. It was found that the three reaction system improved photocatalytic hydrogen evolution, and their activity order is TEOA+Na2S >> TEOA > Na2 S. Few Na2 S adding in the TEOA reactive system has good synergistic effect for enhancing photocatalytic hydrogen evolution. This can be attribute to the prolonged lifetime of photogenerated electron-hole pairs. TEOA itself has been degraded simultaneously while it promoted hydrogen evolution. The effect of initial concentration of TEOA on the hydrogen generation rate is consistent with a Langmuir–Hinshelwood kinetic model. The optimal amount of NiS loaded on the photocatalyst is 2.5 mol%, and the optimal pH is 13.In the second part, using methanol and glucose as electron dornors, the photocatalytic hydrogen evolution over Pt/Cd_0.5Zn_0.5S under visible light irradiation was investigated. It was found that the presence of methanol and glucose significantly improved photocatalytic hydrogen evolution, and their activity order is methanol >>glucose. This is because the smaller methanol molecule is, the faster molecular motion is, more methanol molecules adsorbed on the surface of the catalyst, and effectively improving the ability to capture the hole and hydroxyl radicals. In addition,the more negative shifting of the flat-band potential of Cd_0.5Zn_0.5S in methanol reaction system, enhances the ability of catalyst reduction, thereby increasing the hydrogen production activity. The optimal amount of Pt loaded on the photocatalyst is0.5 mol% in methanol or glucose reaction system; the optimum concentration of NaOH was 3 mol L-1 in methanol reaction system and 2 mol L-1 in glucose reactionsystem. The effect of initial concentration of methanol?or glucose? on the hydrogen generation rate is consistent with a Langmuir–Hinshelwood kinetic model.