Alloying of Au-Pt nanoclusters on thin film Al2O3/NiAl(100)

• Main Authors: Chau-jian Wang, 王朝建
• Other Authors: Meng-fan Luo
• Format: Others
• Language: en_US
• Published: 2009
• Online Access: http://ndltd.ncl.edu.tw/handle/wq49jk

碩士 === 國立中央大學 === 物理研究所 === 97 === We have studied the adsorption and decomposition of methanol on well-defined supported Pt nanoclusters as a model catalyst and the alloying of Au-Pt nanoclusters on thin film Al2O3/NiAl(100) by using synchrotron-based high-resolution photoemission spectroscopy (PES). Pt nanoclusters are deposited on well-ordered Al2O3 film grown on NiAl (100) through vapor deposition in the ultrahigh vacuum conditions (＜3 x 10-10 torr) at 300 K. By using PES we find that the electron structure of Pt doesn’t change with Pt coverage. On annealing to 450 K the oxidized Pt form on the surface. To study methanol decomposition, methanol was adsorbed on Pt/Al2O3/NiAl (100) at 120 K and subsequent annealed to different temperatures. In our annealing experiment, the C1s peak shifts towards higher binding energy with increasing temperature, which is probably due to that the hydrocarbon-species (CHx) adsorb on Pt nanoclusters, and the hydrocarbon-species (CHx) formed at the surface at 300 K. According to the PES results, we observe evident shift for the Au-4f because of the electron transfer from Pt to Au when Au-Pt alloy formed. During the annealing procedure, the intensity of alloy decrease because of the Pt diffuse or oxidization. There are change in intensity of Pt, pure Au, and alloy signals when adsorbing methanol on (annealed) alloy cluster, which is probably due to a specific ratio of Pt to Au in alloy cluster when adsorbed methanol.