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 ...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.展开更多
文摘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.
