Mo（CO）6 adsorption on the clean, oxygen-precovered and deeply oxidized Si（lll） surfaces was comparatively investigated by high-resolution electron energy loss spectroscopy. The downward vibrational frequency shift...Mo（CO）6 adsorption on the clean, oxygen-precovered and deeply oxidized Si（lll） surfaces was comparatively investigated by high-resolution electron energy loss spectroscopy. The downward vibrational frequency shift of the C-O stretching mode in adsorbed Mo（CO）6 illustrates that different interactions of adsorbed Mo（CO）6 occur on clean Si（111） and SiO2/Si（111） surfaces, weak on the former and strong on the latter. The strong interaction on SiO2/Si（111） might lead to the partial dissociation of Mo（CO）6, consequently the formation of molybdenum subcarbonyls. Therefore, employing Mo（CO）6 as the precursor, metallic molybdenum could be successfully deposited on the SiO2/Si（111） surface but not on the clean Si（111） surface. A portion of the deposited metallic molybdenum is transformed into the MoOa on the SiO2/Si（111） surface upon heating, and the evolved MoO3 finally desorbs from the substrate upon annealing at elevated temperatures.展开更多
The co-doping of iron and cerium into TiO2 was studied by means of X-ray diffraction, Raman spectroscopy, UV Vis diffuse reflectance spectroscopy and X-ray photoelectron spectroscopy, when separately doping via the so...The co-doping of iron and cerium into TiO2 was studied by means of X-ray diffraction, Raman spectroscopy, UV Vis diffuse reflectance spectroscopy and X-ray photoelectron spectroscopy, when separately doping via the sol-gel method, iron was introduced in the fralnework of anatase TiO2 whereas cerium was not; interestingly, both iron and cerium were introduced in tile framework when co-doping by the sol-gel method. The co-doped TiO2 behaves much more intense surface hydroxyl concentration than the separately-doped and pure TiO2. This observation demonstrates for the first time a cooperative effect in the co-doping of transitional metals in the framework of TiO2.展开更多
The growth and thermal stability of Au clusters on a partially-reduced rutile TiO2 （110）-1 × 1 surface were investigated by high-resolution photoelectron spectroscopy using synchrotron- radiation-light. The val...The growth and thermal stability of Au clusters on a partially-reduced rutile TiO2 （110）-1 × 1 surface were investigated by high-resolution photoelectron spectroscopy using synchrotron- radiation-light. The valence-band photoelectron spectroscopy results demonstrate that the Ti^3＋3d feature attenuates quickly with the initial deposition of Au clusters, implying that Au clusters nucleate at the oxygen vacancy sites. The Au4f core-level photoelectron spectroscopy results directly prove the existence of charge transfer from oxygen vacancies to Au clusters. The thermal stability of Au clusters on the partially-reduced and stoichiometric TiO2（110） surfaces was also comparatively investigated by the annealing experiments. With the same film thickness, Au clusters are more thermally stable on the partially-reduced TiO2（110） surface than on the stoichiometric TiO2（110） surface. Meanwhile, large Au nanoparticles are more thermally stable than fine Au nanoparticles.展开更多
文摘Mo（CO）6 adsorption on the clean, oxygen-precovered and deeply oxidized Si（lll） surfaces was comparatively investigated by high-resolution electron energy loss spectroscopy. The downward vibrational frequency shift of the C-O stretching mode in adsorbed Mo（CO）6 illustrates that different interactions of adsorbed Mo（CO）6 occur on clean Si（111） and SiO2/Si（111） surfaces, weak on the former and strong on the latter. The strong interaction on SiO2/Si（111） might lead to the partial dissociation of Mo（CO）6, consequently the formation of molybdenum subcarbonyls. Therefore, employing Mo（CO）6 as the precursor, metallic molybdenum could be successfully deposited on the SiO2/Si（111） surface but not on the clean Si（111） surface. A portion of the deposited metallic molybdenum is transformed into the MoOa on the SiO2/Si（111） surface upon heating, and the evolved MoO3 finally desorbs from the substrate upon annealing at elevated temperatures.
文摘The co-doping of iron and cerium into TiO2 was studied by means of X-ray diffraction, Raman spectroscopy, UV Vis diffuse reflectance spectroscopy and X-ray photoelectron spectroscopy, when separately doping via the sol-gel method, iron was introduced in the fralnework of anatase TiO2 whereas cerium was not; interestingly, both iron and cerium were introduced in tile framework when co-doping by the sol-gel method. The co-doped TiO2 behaves much more intense surface hydroxyl concentration than the separately-doped and pure TiO2. This observation demonstrates for the first time a cooperative effect in the co-doping of transitional metals in the framework of TiO2.
基金ACKNOWLEDGMENTS This work was supported by the National Natural Science Foundation of China （No.20773113 and No.20803072）, the Hundred Talent Program of Chinese Academy of Sciences, the MOE Program for Changjiang Scholars and Innovative Research Team （No.IRT0756）, and the MPG-CAS Partner-group Program.
文摘The growth and thermal stability of Au clusters on a partially-reduced rutile TiO2 （110）-1 × 1 surface were investigated by high-resolution photoelectron spectroscopy using synchrotron- radiation-light. The valence-band photoelectron spectroscopy results demonstrate that the Ti^3＋3d feature attenuates quickly with the initial deposition of Au clusters, implying that Au clusters nucleate at the oxygen vacancy sites. The Au4f core-level photoelectron spectroscopy results directly prove the existence of charge transfer from oxygen vacancies to Au clusters. The thermal stability of Au clusters on the partially-reduced and stoichiometric TiO2（110） surfaces was also comparatively investigated by the annealing experiments. With the same film thickness, Au clusters are more thermally stable on the partially-reduced TiO2（110） surface than on the stoichiometric TiO2（110） surface. Meanwhile, large Au nanoparticles are more thermally stable than fine Au nanoparticles.
