Undoped And Rare Earth Ions Of Tio <sub> 2 </ Sub> Preparation And Photocatalytic Hydrogen Law

Photocatalytic water splitting for H₂ evolution by utilizing the solar energy is an attractive and challenging task. Among the most of semiconductor photocatalysts, TiO₂ photocatalyst has received much attention, due to its nontoxicity, low cost, highly stable toward photocorrosion. The study of TiO₂ photocatlytic H₂ evolution is significant not only in practical application, but also in the design of new photocatalytic materials.In this paper, TiO₂ and rare-earth ion doped TiO₂ samples were prepared by acid-catalyzed sol-gel method and characterized by XRD, UV-vis, TEM, BET. The photocatalytic activity for H₂ evolution of the catalysts is carried out in a pyrex reaction cell connected to a closed gas circulation and evacuation system.The results of characterization and photocatalytic activity indicate that raw materials have different effects on the phase transformation temperature and rate, particle size, specific surface area and particle dispersivity, which closely relate to the photocatalytic activity of the catalyst. It is indicated that the sample with well-crystallized anatase, larger surface area and samller particle size, better particle dispersivity has better photocatalytic activity for H₂ evolution. Nd³⁺ doping restrains the growth of grain size, enhances the phase transformation temperature, raises the BET surface area and improves the dispersivity of the particles, thus the doping raised the photocatalytic activity. In this paper, the optimum amount of Nd³⁺ doping is 0.1 at. %. Nd³⁺ doping has little effect on the sample with high BET surface area, small particle and high photocatalytic activity. Different rare-earth-ions doping has different effects on the photocatalytic activity of TiO₂. The samples doped with La³⁺(4f⁰)and Gd³⁺(4f⁷) show high photocatalytic activity for H₂ evolution and the photocatalytic activity of 0.2at. % La³⁺(Gd³⁺)/TiO₂ is about 6 times higher than that of undoped TiO₂. The Dy³⁺(4f¹⁰) doping has little effect on the photocatalytic activity of TiO₂.