通过红外反射吸收光谱和旋转圆盘电极研究重构金单晶表面上一氧化碳的表面电化学。

Surface electrochemistry of CO on reconstructed gold single crystal surfaces studied by infrared reflection absorption spectroscopy and rotating disk electrode.

作者信息

Blizanac Berislav B, Arenz Matthias, Ross Philip N, Marković Nenad M

机构信息

Materials Sciences Division Lawrence Berkeley National Laboratory, University of California, Berkeley, California 94720, USA.

出版信息

J Am Chem Soc. 2004 Aug 18;126(32):10130-41. doi: 10.1021/ja049038s.

DOI:10.1021/ja049038s

PMID:15303889

Abstract

The electrooxidation of CO has been studied on reconstructed gold single-crystal surfaces by a combination of electrochemical (EC) and infrared reflection absorption spectroscopy (IRAS) measurements. Emphasis is placed on relating the vibrational properties of the CO adlayer to the voltammetric and other macroscopic electrochemical responses, including rotating disk electrode measurements of the catalytic activity. The IRAS data show that the C-O stretching frequencies are strongly dependent on the surface orientation and can be observed in the range 1940-1990 cm(-1) for the 3-fold bridging, 2005-2070 cm(-1) for the 2-fold bridging, and 2115-2140 for the terminal position. The most complex CO spectra are found for the Au(110)-(1 x 2) surface, i.e., a band near 1965 cm(-1), with the second, weaker band shifted positively by about 45 cm(-1) and, finally, a weak band near 2115 cm(-1). While the C-O stretching frequencies for a CO adlayer adsorbed on Au(111)-(1 x 23) show nu(CO) bands at 2029-2069 cm(-1) and at 1944-1986 cm(-1), on the Au(100)-"hex" surface a single CO band is observed at 2004-2029 cm(-1). In the "argon-purged" solution, the terminal nu(CO) band on Au(110)-(1 x 2) and the 3-fold bridging band on the Au(111)-(1 x 23) disappear entirely. The IRAS/EC data show that the kinetics of CO oxidation are structure sensitive; i.e., the onset of CO oxidation increases in the order Au(110)-(1 x 2) > or = Au(100)-"hex" > Au(111)-(1 x 23). Possible explanations for the structure sensitivity are discussed.

摘要

通过电化学（EC）和红外反射吸收光谱（IRAS）测量相结合的方法，研究了重构金单晶表面上一氧化碳的电氧化过程。重点在于将一氧化碳吸附层的振动特性与伏安法及其他宏观电化学响应联系起来，包括旋转圆盘电极对催化活性的测量。IRAS数据表明，C - O伸缩频率强烈依赖于表面取向，对于三重桥连结构，其频率范围在1940 - 1990 cm⁻¹；对于二重桥连结构，在2005 - 2070 cm⁻¹；对于端基结构，在2115 - 2140 cm⁻¹。在Au(110)-(1×2)表面发现了最复杂的一氧化碳光谱，即一个在1965 cm⁻¹附近的谱带，第二个较弱的谱带正向偏移约45 cm⁻¹，最后还有一个在2115 cm⁻¹附近的弱谱带。吸附在Au(111)-(1×23)上的一氧化碳吸附层的C - O伸缩频率显示，ν(CO)谱带出现在2029 - 2069 cm⁻¹和1944 - 1986 cm⁻¹，而在Au(100)-“hex”表面观察到一个单一的CO谱带，位于2004 - 2029 cm⁻¹。在“氩气吹扫”溶液中，Au(110)-(1×2)上的端基ν(CO)谱带和Au(111)-(1×23)上的三重桥连谱带完全消失。IRAS/EC数据表明，一氧化碳氧化动力学对结构敏感，即一氧化碳氧化的起始电位按Au(110)-(1×2)≥Au(100)-“hex”>Au(111)-(1×23)的顺序增加。文中讨论了结构敏感性的可能解释。