Photoelectron spectroscopic investigation of the adsorption and catalytic decomposition of formic acid by copper, nickel and gold
Photoelectron spectroscopic investigation of the adsorption and catalytic decomposition of formic acid by copper, nickel and gold
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铜镍金吸附催化分解甲酸的光电子能谱研究
DOI：
10.1098/rspa.1976.0098
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发表时间：
1976
期刊：
影响因子：
--
通讯作者：
M. W. Roberts
中科院分区：
文献类型：
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作者：
R. Joyner;M. W. Roberts
用光电子能谱研究了甲酸在80 ~ 500 K温度范围内与多晶铜、镍和金表面（以及与Cu（100）单晶）的相互作用。在80 ~ 150 K温度范围内，甲酸形成多层膜，紫外光电子能谱（u.（p.s.）与甲酸蒸气的性质相当相似。然而，美国和美国之间存在着微小但重要的差异。P. S. X射线诱导光电子能谱（X. p.s.）。这些差异被证明是在凝聚相的氢键的后果。光谱随温度升高的变化被解释为反映分子转化为甲酸根离子。这被证明涉及以下序列的分子事件：（a）在凝聚相中的氢键裂解，（B）重新取向的分子从平行于被垂直于表面的平面和（c）去除质子。这些结论是基于观察到的表面碳氧比，从O（1 s）和C（1 s）光谱估计，O（1 s）f。W. H. M.值在不同的温度下，在他我和他II光谱的峰的能量和这些与理论计算的甲酸根离子和甲酸分子的轨道的能量的比较。表面物种的光谱监测表明，与金的甲酸根离子分解成气态产物之间的180和200 K;在镍的情况下，在真空中在295 K缓慢发生分解，但与铜，表面形成离子不打破，直到400 K以上。计算了表面阴离子分解的活化能为：Au（50 kJ mol/L），Ni（90 kJ mol/L）和Cu（约100 kJ mol/L）。120kJ mol·1）。研究了费米能级附近的态密度，没有证据表明电子因素参与了催化分解过程。在有限的L。e. e. D.对Cu（100）表面的研究没有得到吸附的甲酸分子或阴离子的有序结构的证据。我们相信这是首次由两个美国的非均相催化反应的调查。和X射线电子能谱，并与以前的红外和催化研究的结果进行了比较。
The interaction of formic acid with polycrystalline copper, nickel and gold surfaces (and with a Cu(100) single crystal) in the temperature range 80‒500K has been studied by photoelectron spectroscopy. Between 80 and 150K formic acid forms multilayers and the ultraviolet photoelectron spectrum (u. p. s.) is rather similar to that of formic acid vapour. There are, however, small but significant differences in the u. p. s. and also in the X-ray induced photoelectron spectrum (X. p. s.). These differences are shown to be a consequence of hydrogen bonding in the condensed phase. Changes in the spectra with increasing temperature are interpreted as reflecting molecular transformation to the formate ion. This is shown to involve the following sequence of molecular events:(a) hydrogen bond cleavage in the condensed phase, (b) reorientation of the molecule from being parallel to being perpendicular to the plane of the surface and (c) removal of a proton. These conclusions are based on the observed surface carbon to oxygen ratio, estimated from the O(1s) and C(1s) spectra, O(1s) f. w. h. m. values at different temperatures, the energies of the peaks in the He I and He II spectra and comparison of these with theoretical calculations of the energies of the orbitals of the formate ion and the formic acid molecule. Spectroscopic monitoring of the surface species showed that with gold the formate ion decomposes into gaseous products between 180 and 200K; in the case of nickel decomposition occurs slowly in vacuo at 295K but with copper, the surface form ate ion does not break down until above 400K. The following activation energies have been estimated for decomposition of the surface anion: Au (50kJ mol‒1), Ni (90kJ mol‒1) and Cu (ca. 120kJ mol‒1). The density of states near the Fermi level has been studied and there is no evidence for the participation of an electronic factor in the catalytic decomposition process. In a limited l. e. e. d. study with a Cu(100) surface no evidence for ordered structures of either the adsorbed formic acid molecule or the anion was obtained. We believe this is the first investigation of a heterogeneously catalysed reaction by both u. v. and X-ray electron spectroscopy, and the results are compared with previous infrared and catalytic studies.