ZnO纳米粒子的表面光电压谱和光催化性能

Surface Photovoltage Spectrum and Photocatalytic Performance of ZnO Nanopartic les

采用焙烧前驱物碱式碳酸锌的方法制备了不同粒径的ZnO纳米粒子 ,而用粒径最小的作为光催化剂 ,通过光还原过程分别得到了贵金属质量分数为 0 .5 %和 0 .75 %的Pd/ZnO或Ag/ZnO复合纳米粒子 .利用XRD ,TEM ,XPS ,SPS和EFISPS等测试技术对样品进行了表征 ,并通过光催化氧化气相正庚烷评估了样品的光催化活性 ,考察了微晶尺寸和贵金属Pd或Ag的沉积对ZnO纳米粒子表面光电压信号以及光催化活性的影响 ,探讨了样品表面光电压谱与其光催化活性的关系 ,说明了可以通过表面光电压谱的测试来初步地评估纳米粒子的光催化活性 .结果表明 :随着ZnO纳米微晶尺寸的减小 ,其SPS信号强度逐渐变弱 ,而光催化活性逐渐升高 ;沉积适量的贵金属Pd或Ag后 ,ZnO纳米粒子的SPS信号强度明显下降 ,而其光催化活性却有所升高 .此外 。

ZnO nanoparticles with different size were prepared by calcining the precursor, zinc carbonate hydroxide, at different temp erature, and Pd/ZnO or Ag/ZnO composite nanoparticles with the noble metal conte nt of w=0.5% and 0.75% were obtained by photoreduction method using the smal lest ZnO nanoparticles as photocatalysts. The as-prepared samples were also cha racterized by the techniques such as XRD, TEM, XPS, SPS and EFISPS, and their photocatalytic activity was evaluated by the photocatalytic degradation of gas p hase n-heptane. The effects of the crystallite size and the deposit of nobl e Pd or Ag on the surface photovoltage responses and photocatalytic activity of ZnO nanaparticles were investigated, and the relations between the surface photo voltage spectrum and photocatalytic activity were discussed. It could be conclud ed that the photocatalytic activity of nanoparticles could be preliminarily eval uated by the measurement of their SPS. The results indicate that the intensity o f SPS signal of ZnO nanoparticles decreases with decreasing size, while the phot ocatalytic activity increases; the intensity of SPS signal of ZnO nanopartic les decreases remarkably after depositing the appropriate noble metal on their s urface, while the photocatalytic activity increases. In addition, the deactivit y mechanism of the photocatalyst of ZnO nanoparticles was also analysed.