Pd/ZnO和Ag/ZnO复合纳米粒子的SPS和XPS研究

用焙烧前驱物碱式碳酸锌的方法制备了ZnO纳米粒子，采用光还原沉积贵金属的方法分别得到了质量分数为0.5％的Pd/ZnO和Ag/ZnO复合纳米粒子，并利用XRD、TEM、XPS和SPS等测试技术对样品进行表征.初步探讨了贵金属在ZnO纳米粒子表面形成原子簇的原因及沉积贵金属对ZnO纳米粒子表面光电压信号的影响.以光催化氧化气相正庚烷为模型反应，考察了沉积贵金属对ZnO纳米粒子光催化活性的影响，并探讨了光催化活性有所提高的内在原因.结果表明， ZnO纳米粒子沉积贵金属后，其表面光电压信号明显下降，而光催化活性却大大地提高，这说明可以通过表面光电压谱的测试来初步的评估纳米粒子的光催化活性，即粒子的表面光电压信号越弱，其光催化活性越高.

Study of SPS and XPS of Pd/ZnO and Ag/ZnO Composite Nanoparticles

ZnO nanoparticles were prepared by c alcining the precursor,zinc carbon ate hydroxide,and Pd /ZnO and Ag /ZnO composite nanoparticles with the noble metal content of 0.5%(mass fraction)were obtained by photoreduction method.The as-prep ared samples were also characterized by the XRD,TEM,XPS and SPS techniques,respectively.The resu lts showed that the deposited noble m etal of both Pd and Ag existed as the fo rm of atomic clusters,and the possible reasons of forming the atomic cluste rs of noble metal on the surface of ZnO nanoparticles were primarily discu ssed.The intensity of SPS responses of ZnO nanoparticle remarkably decreased by depositing the appropriate noble metal on its surface.Moreover,Pd /Z nO and Ag /ZnO composite nanopar-ticles exhibited higher photocatalytic activity than ZnO nanoparticle s in the experiment of photocatalytic oxidation of gas phase n-heptane.The essential reasons why the photocatalytic activity of ZnO n anoparticles improved by depositing noble metal Pd or Ag on its surface were also further discussed.In addition,the point was put forwa rd that the photocatalytic activity of nanoparticle could be primarily evaluated by its SPS response,i.e.,the weaker the SPS responseis,the higher the photoactivity.