甲醇在粗糙铂电极上解离吸附的表面拉曼光谱

甲醇由于具有高能量密度及易于储存等优点，在燃料电池研究领域中备受关注．一般认为，甲醇在铂电极上的电氧化为双途径机理，即首先解离吸附在电极表面上，生成毒性中间体（CO）或活性中间体，然后再氧化生成CO。由于各研究小组使用的电极材料、预处理方法、溶液的组成以及检测手段不同，目前对甲醇的具体解离过程的细节尚未确定（如在反应条件下吸附物的特性及作用、表面结构和粗糙度的特殊影响等），还有待于建立或改进有关原位研究方法．在研究甲醇的电催化氧化的各种检测手段中，红外光谱应用得最为广泛，可用于原位红外技术中的电极…

Surface Raman Spectra of Methanol Dissociatively Adsorbed at Roughened Platinum Electrodes

For the first time, we have obtained surface Raman spectra of dissociative adsorption of methanol at bare Pt electrodes of different surface roughness factors from 60 to 200 by using a confocal Raman microscope and a specific surface roughening procedure. Two bands at around 1 830 cm-1 and 2 040 cm-1 respectively have been assigned to the CO streching vibration of the dissociatively adsorbed CO as the poison Intermediate on the surface. In the low frequency region, the two correlated bands at ca 413 cm-1 and 494 cm-1 respectively provide a clear vibrational information that there exist the linear bonded Pt-CO and bridge bonded P'jO. On the Pt electrode with mild roughness, the Raman signal of CO peared at -0. 4 V, whereas it was still observable on the Pt electrode with high roughness.This reveals that the CO-substrate interaction is stronger for the platinum with the higher surface roughness, at least partly due to the supercluster interaction of the roughened electrode. In addition, the highly rough surface may be favorable to the formation of island CO,thus enhance the interaction between molecules. It has been shown that surface Raman spectroscopy has two advantages: first, It provides a uniquely sensitive probe for obtaining surface-adsorbate vibration information in the low frequency region which is typically not accessible to IR spectroscopy. Second, it can be applied to the study of highly roughened electrodes that are common for practical use. With its notable improvements in detection sensitivity and functions, Raman spectroscopy will probably become a powerful tool to in-situ study electrocatalysis of practical importance.