摘要
低温(110～130K)下,将次表层Fe结构的Pt-Fe模型催化剂(即Pt/Fe/Pt(111)结构)暴露于不同量CO气体,经不同温度退火后,采用高分辨电子能量损失谱(HREELS)研究催化剂表面CO分子的振动谱。结果表明,当CO的暴露量低于0.2 L (Langmuir)时,Pt/Fe/Pt(111)表面只存在顶位吸附;当暴露量大于0.4L,除了顶位吸附外,桥位吸附开始出现;顶位吸附分子的C-O键振动峰随着暴露量的增加不断向高波数方向偏移。退火温度影响Pt/Fe/Pt(111)表面CO的吸附形式,低于255K时,顶位吸附分子的脱附速率大于桥位吸附分子;高于255 K时,桥位吸附分子的脱附速率较大,并先于顶位吸附的CO从表面完全脱附,其完全脱附温度比Pt(111)表面低50 K。
Vibration spectra of adsorbed CO molecules have been probed on subsurface Fe structure of Pt-Fe model catalysts, designated as Pt/Fe/Pt(111), after CO exposures at cyrogenic temperatures (110~130 K) and UHV annealing at stepwise temperatures, by high resolution energy loss spectroscopy (HREELS) technique. When the CO exposure was < 0.2 L, CO species were observed to adsorb only at top-sites. When the exposure was increased to around 0.4 L, CO species at bridge-sites were observed too. Furthermore, the peak of C-O bonds of top-site CO was observed to shift gradually towards higher wavenumbers. The adsorption of CO molecules on Pt-Fe/Pt(111) surface was also influenced by the annealing temperatures. At 255 K, the desorption rate of top-site CO was higher than that of bridge-site CO. While above 255 K, bridge-site CO molecules had a high desorption rate than that of top-site CO molecules, and the complete desorption temperature of bridge-site CO molecules is 50 K lower than that of Pt(111).
作者
马腾
焦科燃
徐美奇
陈伟
王亚琴
MA Teng;JIAO Keran;XU Meiqi;CHEN Wei;WANG Yaqin(Institute of Science,Shenyang Agricultural University,Shenyang 110866,China;School of Environmental and Chemical Engineering,Shenyang Ligong University,Shenyang 110159,China)
出处
《贵金属》
CAS
CSCD
北大核心
2019年第1期1-5,11,共6页
Precious Metals
基金
沈阳农业大学天柱山学者计划
国家自然科学基金(No.21401131)
