Preparation Of CeO₂/TiO₂ And Study Of Its Photocatalytic Hydrogen Production

Energy is one of the most main factors influence the social development. Hydrogen, as a safe and clean alternative energy source, has attracted numearous attention of researchers. Today photocatalytic splitting of water into hydrogen receive much concern. Titanium dioxide（TiO₂） has attracted strong attention due to its outstanding mechanical, thermal, electrical and photocatalytic properties. However, pure TiO₂ light electrons and holes are easy to be compound. In addition, TiO₂ has wide band gap that causes low efficiency of the pure TiO₂ photocatalytic splitting of water into hydrogen. In this artical, CeO₂/TiO₂ is prepared, characterized and methanol as sacrificial agent, The activity of catalyst through the photolysis of methanol aqueous solution of hydrogen production, and all work can be divided into two following parts.Firstly, CeO₂/TiO₂ photocatalysts are prepared by loading cerium on TiO₂ with sol-gel synthesis approach. The materials were prepared using Tetrabutyl titanate, Cerium nitrateas as raw material. The amount of compound cerium, concentration of sulfuric acid dipping, calcination temperature on the CeO₂/TiO₂ photocatalyst activity of hydrogen production were investigate. Through the photolysis of methanol aqueous solution experiments show, The best conditions of CeO₂/TiO₂ were abtained when the molar ratio of cerium and titanium were 33.3%, calcination temperature 600℃, acid concentration 1.5%, The rate of H2 evolution was increased by up to about 89.7mmol/h. The prepared catalyst’s structure and morphology were characterized by X-ray diffraction（XRD）, Scanning Electron Microscope（SEM）, Fluorescence spectrum（PL）, Transmission electron microscopy（TEM）, Ultraviolet-visible diffuse reflectance spectroscopy（UV-vis DRS）, Specific surface area（BET） and X-ray photoelectron spectroscopy（XPS）. The experimental results show that cerium oxide structure and composite volume in splitting water into hydrogen plays a key role. Through the Ultraviolet-visible diffuse reflectance spectroscopy（UV-vis DRS） and Specific surface area（BET） shows that the specific surface area and red shift in the catalyst which increasing the catalyst for the absorption of visible light. Through the Transmission electron microscopy（TEM）, X-ray diffraction（XRD）, Fluorescence spectrum（PL） show that CeO₂/TiO₂ formed heterojunction for the introduction of cerium, so promote the light carrier separation. Through the py-FTIR and X-ray photoelectron spectroscopy（XPS） show that the samples have obvious L acid and B acid center and have Ce⁴⁺ and Ce³⁺ in the XPS. Therefore, the compounds of CeO₂/TiO₂ have excellent electron transfer properties. Eventually lead to the photocatalytic activity improved.Secondly, CeO₂/TiO₂ photocatalysts are prepared by hydrothermal method using Tetrabutyl titanate, Cerium nitrateas as raw material. CeO₂/TiO₂ photocatalysts are surveyed througth the activity of hydrogen production for the hydrothermal temperature and time, different cerium titanium. Through the photolysis of methanol aqueous solution experiments show, the best conditions of CeO₂/TiO₂ were abtained when the molar ratio of cerium and titanium were 28.6%, hydrothermal temperature 160℃, hydrothermal time 12 hours. The rate of H2 evolution was increased by up to about 58.23mmol/h. The prepared catalyst’s morphology and spectrum range were characterized by X-ray diffraction（XRD）, Scanning Electron Microscope（SEM）, Transmission electron microscopy（TEM）, Fluorescence spectrum（PL）, Ultraviolet-visible diffuse reflectance spectroscopy（UV-vis DRS） and Specific surface area（BET）. The composites of CeO₂/TiO₂ form the layered films through the analysis of SEM. The experimental results show that addition of Ce atoms in Ti O₂ plays a important role in the process of hydrogen. Not only increased the specific surface area, but also made red shift in the catalyst which increasing the catalyst for the absorption of visible light.