Adsorption of CN at the Pt(111)/liquid interface by dissociation of acetonitrile and the potentiality of CO contamination: a sum-frequency generation study
Adsorption of CN at the Pt(111)/liquid interface by dissociation of acetonitrile and the potentiality of CO contamination: a sum-frequency generation study
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DOI：
10.1021/jp0033216
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发表时间：
2001-05
影响因子：
3.3
通讯作者：
F. Dederichs;A. A. Petukhova-A.;W. Daum
中科院分区：
文献类型：
--
作者：
F. Dederichs;A. A. Petukhova-A.;W. Daum
本文用表面振动和频产生（SFG）技术和循环伏安法研究了乙腈（CH_3CN）解离CN在Pt（111）表面上的吸附。吸附过程涉及冷却的火焰退火的Pt晶体以上的乙腈（0.1 M HClO 4 + 0.025 M CH 3CN）的稀水溶液，然后通过浸入到电解质中的样品。吸附的物种被确定为氰化物的特征电位依赖的伸缩频率，从2087 cm-1在0.1 V增加到2136 cm-1在0.95 V，以及通过循环伏安法。与在1 × 10-3 M乙腈溶液中的伏安图比较表明，解离发生在溶液上方的气相中。在我们的光谱中，频率接近2155 cm-1的第二个谱带被暂时指定为Pt-氰基表面络合物。我们还报告了实验中，相同的退火/冷却程序已被应用于使用纯净的液体乙腈。这些样品的SFG光谱中的1860和2073 cm-1附近的频带被示出源自吸附的CO，最有可能产生的CH 3CN蒸气在热的Pt晶体的氧化。CN吸附在Pt（111）/液体乙腈界面，通过沉积的氰化物离子从四丁基氰化铵在乙腈中的溶液进行，其特征在于由一个单一的带附近2110 cm-1。
The adsorption of cyanide, CN, on the Pt(111) surface by dissociation of acetonitrile, CH3CN, has been investigated by sum-frequency generation (SFG) as surface vibrational spectroscopy and by cyclic voltammetry. The adsorption procedure involved cooling of the flame-annealed Pt crystal above a dilute aqueous solution of acetonitrile (0.1 M HClO4 + 0.025 M CH3CN), followed by immersion of the sample into the electrolyte. The adsorbed species is identified as cyanide by the characteristic potential dependence of the stretching frequency, which increased from 2087 cm-1 at 0.1 V to 2136 cm-1 at 0.95 V, as well as by cyclic voltammetry. Comparison with the voltammogram in a 1 × 10-3 M solution of CH3CN indicates that the dissociation takes place in the gas phase above the solution. A second band in our spectra with a frequency near 2155 cm-1 is tentatively assigned to a Pt−cyano surface complex. We also report on experiments in which the same annealing/cooling procedure has been applied using neat liquid acetonitrile. Bands near 1860 and 2073 cm-1 in SFG spectra of these samples are shown to originate from adsorbed CO, most likely produced by oxidation of CH3CN vapor at the hot Pt crystal. CN adsorption at the Pt(111)/liquid acetonitrile interface, performed by deposition of cyanide ions from solutions of tetrabutylammonium cyanide in acetonitrile, is characterized by a single band near 2110 cm-1.