Studies On Preparation Of Cadmium Sulfide Semiconductor Photocatalyst And Its Photocatalytic Performance

In this thesis the preparation and modification of CdS semiconductor photocatalyst as well as its photocatalytic performance for hydrogen production was searched. The reseach works is composed of two parts:The first part was the study on preparation of nanocrystalline CdS by hydrothermal or solvent thermal process and its photocatalytic performance. Hydrothermal process and solvent thermal process have been successfully applied to prepare nanocrystalline CdS via the reaction of CdSO₄ with Na₂S or thioacetamide. The samples were characterized by XRD, UV-Vis spectrophotometer. The effects of the conditions for preparation of nano-CdS on the photocatalytic activity were investigated through a photocatalytic H₂ production from formic acid solution under visible light irradiation as a probe reaction. Electrical-chemical analyzer was employed to determine the photocorrosion of CdS. It was found that solvent, reactants and temperature have significantly affected on crystal structure and particle size of CdS nanocrystalline, which affected the catalytic activity. The results show that the photocorrosion is affected by crystal structure and decreases with the increase of crystallinity of CdS nanocrystalline. The results demonstrate that higher activity and lower photocorrosion CdS nano-photocatalyst can be prepared by controlling preparation conditions.The second was the study on enhancement of photocatalytic activity of cadmium sulfide for hydrogen evolution by photoetching. CdS semiconductor photocatalyst was synthesized by a solvent thermal process. Platinum (Pt) was loaded on the CdS by photodeposition. The samples were characterized by XRD, BET, TEM, PL and XPS techniques. The activities of Pt/CdS photocatalysts under visible light were evaluated by hydrogen production using formic acid as electron donor. Photoetching of CdS was monitored by measuring dissolved Cd²⁺ using an electrochemistry method. The activity of Pt/CdS with 1 h photoetching treatment increases by 126 % compared to the initial photocatalyst. However, excess photoetching decreases the photocatalytic activity. A distinct correlation between photoetching and increase of the activity is observed. Oxygen and Pt play an important role in the photoetching...