S、La^3＋共掺杂TiO2的制备及其可见光下光催化制氢性能

Preparation of TiO_2 Codoped with S and La^(3+) and Performance of Photocatalytic Hydrogen Evolution under Visible Light Irradiation

采用溶胶-凝胶法制备了S、La3+共掺杂TiO2可见光光催化剂.通过UV-Vis DRS、XRD、XPS、电化学等手段对催化剂进行了表征.以可见光光催化制氢为探针反应考察了催化剂的活性.结果表明:两种元素掺杂没有改变TiO2的晶型,但掺杂后增强了TiO2晶格畸变;La3+掺杂显著地提高了S/TiO2的可见光活性.相对于纯TiO2和S/TiO2,S、La3+共掺杂时TiO2的粒径更小,平带电位负移更明显,光的吸收边带红移更显著.当S、Ti的量比n(S)/n(Ti)为5∶1、La3+掺杂量(质量分数)为0.75%、煅烧温度为450℃时,La3+/S/TiO2的光催化活性最高.

A visible-light TiO2 photocatalyst codoped with La^3＋ and S （La^3＋/S/TiO2） was prepared by sol-gel method and characterized by UV-Vis diffuse reflectance spectroscopy, X-ray diffraction, X-ray photoelectron spectroscopy and electrochemistry. The activity of the prepared photoeatalyst under visible light irradiation was evaluated by photocatalytic hydrogen evolution. It is found that doping of La^3＋ and S does not change crystalline style of TiO2, but enhances the lattice distortion. The visible-light （λ〉420 nm） activities of La^3＋ doped S/TiO2 samples greatly increase compared with that of S/TiO2. The size of La^3＋/S/TiO2 gets more little than that of pure TiO2 and S/TiO2, the flat-band potential of conduction shifts notably negatively, and the absorption edge shifts remarkably toward long wavelength. When the mol ration of S/TiO2, the doping content of La^3＋ and the calcinated temperature are 1 ： 5, 0. 75% and 450 ℃, respectively, the catalyst is endowed with the highest activity.