摘要
采用溶胶-凝胶法制备Gd3+掺杂SiO2/TiO2(Gd3+-SiO2/TiO2,GST)。用X射线衍射(X-ray diffraction,XRD)仪、热重-差热分析仪、紫外-可见分光光度计(ultraviolet-visible spectrophotometry,UV-Vis)及X射线光电子分光仪(X-ray photoelectron spectroscopy,XPS)等研究GST的结构特性,并以水中腐殖酸的降解及矿化评价GST的光催化活性。XRD分析结果表明:Gd3+掺杂能有效抑制TiO2晶型的转变及催化剂晶粒的增长,GST在700℃时仍保持锐钛矿型。UV-Vis分析表明:Gd3+掺杂使催化剂对光的吸收能力大大增强且吸收带边发生蓝移。XPS谱表征证实:GST的表面缺陷(Ti3+)及晶格氧的含量增多。结果表明:当Gd3+的质量掺量为0.4%,700℃焙烧的GST在中性条件下反应150 min后,能使HA彻底降解,有机碳的残余率达3%。经分析可知:带隙的宽化使光生h+-e-的氧化-还原能力增强,GST表面Ti3+及晶格氧含量的增加使催化剂表面的活性位增多,Ti3+和Ti4+的共存形成的电荷层增强了催化剂对电荷的传输效率,是GST能够彻底降解水中HA的主要原因。
Silica/titania doped with Gd3＋（Gd3＋-SiO2/TiO2,GST） was prepared using sol–gel method.Structural characteristics of GST were analyzed by X-ray diffraction（XRD）,thermogravimetric–differential thermal analysis,ultraviolet–visible spectrophotometry（UV–Vis）,and X-ray photoelectron spectroscopy（XPS）,and photocatalytic activity of GST was evaluated according to degradation and mineralization of humic acid in water.The XRD results show that Gd3＋ doping inhibits phase transformation of TiO2 and catalyst grain size increases,with GST remaining in anatase phase at 700 ℃.The UV–Vis analysis clearly indicates that Gd3＋ doping enhanced light absorption ability of catalyst and results in a blue shift of absorption edge.The XPS results indicate that there are more surface defects with the presence of Ti3＋ and lattice oxygen.Experimental results show that humic acid is completely degraded with the residual rate of organic carbon reaching 3% at pH = 6.5 after 150 min when the Gd3＋ is present at 0.4%（in mass） in GST calcined at 700 ℃.The main reasons for the complete degradation of humic acid in water by GST may be： wide band gap enhances the oxidation–reduction capability of photoproduction h＋–e–,the increasing Ti3＋ and lattice oxygen content improves the active sites on the catalyst surface,and the charge layer formed by the coexistence of Ti3＋ and Ti4＋ on the surface enhances the efficiency of charge transfer in GST.
出处
《硅酸盐学报》
EI
CAS
CSCD
北大核心
2011年第9期1477-1482,共6页
Journal of The Chinese Ceramic Society
基金
国家自然科学基金(20776091)资助项目
关键词
钆离子掺杂
硅钛复合氧化物
光催化活性
腐殖酸
gadolinium ion doped
silica-titania composite oxide
photocatalytic activity
humic acid
