应用同步辐射原位研究铈锆复合氧化物模型催化剂的结构和性能

Under controlled conditions in ultrahigh vacuum systems, thin ordered ceria/zirconia mixed oxide films will be prepared on the metal single crystal substrates. The electronic and geometric structures and mophologies of the ceria/zirconia mixed oxide surfaces as well as their relationship to the Ce/Zr ratios will be investigated in-situ by using synchrotron radiation photoemission spectroscopy and soft X-ray near-edge absorption fine structure, in combination with other surface science techniques such as low energy electron diffraction and scanning tunneling microscopy. Moreover, the adsorption and reaction of metal nanoparticles and probing molecules on the ceria/zirconia mixed oxide surfaces will be studied. In detail, we will mainly address on the following issues: (1) the interaction bewteen metal nanoparticles and the mixed oxide surfaces; (2) the growth, diffusion and agglomeration of metals on the mixed oxide surfaces; (3) the chemical states and electronic structures of adsorbed metal particles; (4) the above-mentioned processes and properties as a function of annealing temperatures; (5) the adsorption states and reaction mechanisms of the probing molecules on the surfaces of ceria/zirconia mixed oxides and metals supported on ceria/zirconia model catalysts; (6) the relationship bewteen the Ce-Zr chemical compositions and their catalytic properties. In combination with the theoretical calculations on the same systems, we attempt to gain deep insight into the intrinsic relationship between the surface structures of the ceria/zirconia mixed oxides and their adsorption and catalytic properties.

利用超高真空可控原位样品制备技术，在金属单晶衬底上制备有序铈锆复合氧化物薄膜；运用同步辐射光电子能谱和近边X 射线吸收精细结构等表征技术结合低能电子衍射和扫描隧道显微镜等技术，研究铈锆复合氧化物薄膜表面的电子结构、位相结构和表面形貌及其他们与铈锆组成的关系；研究纳米金属粒子和探针气体分子在此薄膜表面上的吸附和反应，考察金属与铈锆复合氧化物表面相互作用的本质、金属在复合氧化物表面上的生长、扩散或聚集过程和金属的化学态、电子结构以及它们随温度发生的变化等；研究探针气体分子在铈锆复合氧化物及金属/铈锆复合氧化物模型催化剂表面上化学吸附或反应的过程和机理；探索调变铈锆复合氧化物中铈/锆比对其表面催化和吸附性能的影响等。结合理论计算，获得铈锆复合氧化物表面结构与其吸附和催化性能之间内在联系的信息。

利用超高真空原位样品制备技术，在金属Pt(111)、Ru(0001)和Cu(111)衬底上分别原位外延制备了ZrO2(111)、CeO2(111)和铈锆复合氧化物（CexZr1-xO2）模型氧化物表面，并在此基础原位制备了Ag/CeO2、Ni-Ag/CeO2、Ag/ZrO2和Ag/CexZr1-xO2等模型催化剂体系，利用先进的同步辐射技术如同步辐射光电子发射谱（SRPES）等结合扫描隧道显微镜（STM）和低能电子衍射（LEED）等考察了催化剂的表面微观结构（包括电子结构和几何结构）、形貌和热稳定性等，在原子－分子水平上获得了催化剂表面金属－载体相互作用的本质、影响催化剂稳定性的因素等。此外，利用该项目的资助，我们还研究了Sm/Al2O3模型催化剂的O2吸附和反应、铁氧化物在光解水方面的应用、基于金属-有机骨架（MOF）材料在催化降解有机物和催化产氢、Li/S电池的阴极材料在充放电过程中的电子结构的变化等。这些成果为揭示催化剂的结构与性能关系、优化和提高催化剂的催化性能提供坚实的理论基础。截止2015年12月31日，已发表标注项目资助的SCI论文16篇，培养毕业博士生4名、硕士生1名；参加国内外学术会议十多次，邀请国外学者访问10次。