摘要
用H2气还原法制备了表面沉积Ag的纳米TiO2,通过对样品SEM、XRD、UV Vis漫反射光谱分析,结 果表明,金属Ag在TiO2表面呈细小而均匀的分布,UV Vis光谱上的吸收阈值显著红移。以紫外灯和太阳光 为光源,甲基橙为目标物,评价了沉积Ag的TiO2催化剂活性。实验表明,Ag的最佳沉积量为0.25%(摩尔分 数),在300℃以内,焙烧温度对活性影响不大。在紫外光降解反应中,催化剂用量为1.25g/L时降解率最高, 弱酸性条件有利于光降解反应,反应液总体积越小,单位体积光照强度越大,光降解活性越高,过氧化物的加 入对反应活性有显著提高。在使用不同催化剂时,甲基橙分解反应能较好的符合一级反应动力学。与纯TiO2 相比,在太阳光下,Ag/TiO2光催化剂对甲基橙有较高的降解活性。
Ag was deposited by H 2 reduction on the surface of TiO 2 nanoparticles. The results of SEM, XRD and UV-vis show that Ag distributes uniformly on the TiO_2 surface and the Einstein shift can be observed clearly in the UV-vis adsorption spectrum. UV and sunlight were used as light sources to investigate the photocatalytic activity of the Ag/TiO 2 composite catalyst for the degradation of methyl orange. The results show that the optimized amount of deposited Ag is 0.25%(molar ratio of Ag to TiO_2) and the calcination temperature influences slightly the photocatalytic activity when it is lower than 300 ℃. For the UV light degradation reation, the optimum photocatalyst concentration was determined to be 1.25 g/L. Both weakly acidic condition and the presence of peroxide are of great advantage to the light degradation reaction. The photocatalytic activity increases with the decrease of the total volume of the solution or the increase of the illumination intensity in unit volume. The degradation of methyl orange follows first-order reaction kinetics for different catalysts. Compared with pure TiO_2, Ag/TiO_2 shows higher photocatalytic activity when it is used to degrade methyl orange under sunlight.
出处
《应用化学》
CAS
CSCD
北大核心
2005年第2期132-137,共6页
Chinese Journal of Applied Chemistry
基金
国家"八六三"计划资助项目(2001AA2180041)
关键词
纳米TIO2
银沉积
光催化
甲基橙
nano TiO_2,silver deposition,photocatalysis,methyl orange
