论文部分内容阅读
The interaction of Co with ceria thin films and its influence on the sintering behavior of Au were investigated by scanning tunneling microscopy(STM), synchrotron radiation photoemission spectroscopy(SRPES) and X-ray photoelectron spectroscopy(XPS). The strong interaction between Co and CeO_2(111) leads to oxidation of Co to Co~(2+) at 300 K, accompanied by partial reduction of ceria surface at low Co coverages. Subsequent Co deposition results in an increasing fraction of metallic Co. Annealing to high temperatures induces Co~(2+)ions diffuse into the CeO_2 film, while the small metallic Co islands agglomerate into larger ones. The bimetallic Co–Au particles were prepared by deposition of Au on the existing Co particles on ceria surfaces. The sintering behavior of Co–Au bimetallic surfaces is found to be highly determined by the stoichiometry of ceria supports. The addition of Co to the Au/CeO_2 surface suppresses the sintering of Au particles at high temperatures in comparison with that of pure Au particles. However, Au particles are less stable on the Co/CeO_(1.82) layer than on CeO_(1.82) surface.
The interaction of Co with ceria thin films and its influence on the sintering behavior of Au were investigated by scanning tunneling microscopy (STM), synchrotron radiation photoemission spectroscopy (SRPES) and X-ray photoelectron spectroscopy (XPS). The strong interaction between Co and CeO 2 (111) leads to oxidation of Co to Co 2+ (2+) at 300 K, accompanied by partial reduction of ceria surface at low Co coverages. Subsequent Co deposition results in an increasing fraction of metallic Co. Annealing to high temperatures induces Co ~ (2+) ions diffuse into the CeO_2 film, while the small metallic Co islands agglomerate into larger ones. The bimetallic Co-Au particles were prepared by deposition of Au on the existing Co particles on ceria surfaces. The sintering behavior of Co- Au addition of Co to the Au / CeO 2 surface suppresses the sintering of Au particles at high temperatures in comparison wi th that of pure Au particles. However, Au particles are less stable on the Co / CeO 1.82 layer than on CeO 1.82 surface.