锌掺杂对SrTiO_3光催化性能的影响

制备了锌掺杂的SrTiO3光催化剂,测试了掺杂样品在400 W高压汞灯照射下,分解纯水制氢的活性。考察了锌的掺杂量及样品的焙烧温度对其光催化活性的影响,并对掺锌与未掺杂样品进行了XRD、UV-vis、XPS及SEM表征分析。结果表明,Zn掺入可显著提高SrTiO3的光催化活性,适宜的锌掺杂摩尔分数为1%左右,相应的掺杂量下,适宜的焙烧温度为950℃左右,上述条件制得掺锌SrTiO3的产氢速率较未掺杂样品提高了120%左右。表征结果显示,掺摩尔分数1%的锌未改变SrTiO3的晶体结构及结晶完整性,但样品表面发生了锌的富集,而且在一定的掺杂范围内,锌掺杂使SrTiO3催化剂的粒度有所增大。推测掺入的Zn与存在于SrTiO3表面的富钛相反应生成Zn2TiO4,使SrTiO3表面的缺陷浓度降低,光催化活性提高。

Influence of Zn doping on the photocatalytic property of SrTiO3

The Zn doped SrTiO₃ photocatalysts were synthesized and the photocatalytic activity of the doped samples for water decomposition to hydrogen was measured under the irradiation of a high pressure Hg lamp (400W). The influence of doping amount of Zn and the calcination temperature on the photocatalytic activity were investigated. The physical properties of catalysts with and without Zn doping were characterized using XRD, XPS, SEM and UV-visible diffuse reflectance spectra. The experimental results show that Zn doping greatly improves the photocatalytic activity of SrTiO₃. The optimum molar doping amount of Zn is about 1%, and in this case, the suitable calcination temperature is about 950℃. Under this condition, the photocatalytic property of Zn doped SrTiO₃ is 2.2 times higher than that of the undoped one. The characterization results indicate that 1% Zn doping does not change the crystal structure and crystal perfection properties of SrTiO₃. However, doping element Zn is enriched on the surface of SrTiO₃ sample. In addition, the crystal size increases within a certain range of Zn doping. It can be predicted that Zn2TiO₄ is generated by the incorporated Zn reacting with the Ti-rich phase existed on the SrTiO3 surface, which leads to the decrease of the surface defect concentration of SrTiO₃, and consequently increases the photocatalytic activity of Zn doped SrTiO₃.