可见光响应型Fe掺杂SiO_2/TiO_2光催化材料的制备及降解水中腐殖酸的研究

Preparation of Fe Doped SiO_2/TiO_2 Photocatalytic Material Response to Visible Light and Degradation of Humic Acid in Water

采用溶胶凝胶法制备了可见光响应型Fe掺杂SiO2/TiO2光催化材料,并采用TG-DTA、XRD、UV-vis、TEM及XPS等手段对其进行了表征。以水中腐殖酸的降解为探针反应,考察了可见光照射下Fe-SiO2/TiO2的光催化活性。XRD结果表明,Fe离子掺杂可抑制催化剂晶粒尺寸,600℃焙烧后的Fe-SiO2/TiO2为锐钛矿相结构。Uv-vis吸收光谱分析可看出Fe离子掺杂提高了催化剂对可见光的吸收能力,并使催化剂的吸收带边产生了红移。XPS光谱表明,催化剂表面存在着Fe2+和Fe3+。实验结果表明,Fe-SiO2/TiO2在可见光下对腐殖酸的光催化降解率优于SiO2/TiO2和TiO2。Fe-SiO2/TiO2具有较高光催化活性的主要原因为:Fe离子掺杂不仅使SiO2/TiO2催化剂的粒径减小和对可见光的吸收增强,而且在催化剂表面产生了有利于光生e--h+对分离的Fe3+/Fe2+氧化还原循环电对。

Photocatalytic material of SiO2/TiO2 doped with Fe responded to visible light was prepared by sol-gel process and characterized using TG-DTA,XRD,UV-vis,TEM and XPS analysis methods in detail.The degradation of humic acid in water was chosen as a probe reaction to study the photocatalytic activity of Fe-SiO2/TiO2 under visible light irradiation.XRD results showed that Fe doping inhibited the catalyst grain size,with Fe-SiO2/TiO2 remaining in the anatase phase at 600 ℃.UV-Vis absorption spectra clearly indicated that Fe doping enhanced the visible light absorption ability of the catalyst and resulted in a red shift of the absorption edge.XPS spectra indicated that Fe2＋ and Fe3＋ were existed on catalyst surface.Experimental results showed that the photocatalytic degradation rate of HA of Fe-SiO2/TiO2 sample was better than that of SiO2/TiO2 and TiO2 under visible light irradiation.The main reasons for high photocatalytic activity of Fe-SiO2/TiO2 may be reduce of grain size,the enhance of visible absorption strength,and existent of circular electronic Fe3＋/Fe2＋ in favor of separation the e——h＋ pairs by doping Fe ion.