Surface-Enhanced Infrared Absorption of CO on Platinized Platinum

• Published in: Analytical chemistry (Washington) Vol. 71; no. 10; pp. 1967 - 1974
• Main Authors: Bjerke, Amy E, Griffiths, Peter R, Theiss, Wolfgang
• Format: Journal Article
• Language: English
• Published: Washington, DC American Chemical Society 15-05-1999
• Subjects: Adsorption; Chemistry; Electrochemistry; Exact sciences and technology; General and physical chemistry; Platinum; Scientific imaging; Study of interfaces; Infrared spectrometry; Electrode adsorption; Platinum; Adsorption capacity; Electrode electrolyte interface; Adsorption structure; Transition metal; Carbon monoxide; Rough surface; Experimental study; Disk electrode
• ISSN: 0003-2700; 1520-6882
• DOI: 10.1021/ac981093u

We report here the first observation of surface-enhanced infrared spectroscopy on platinized platinum surfaces, as well as a thorough explanation of the resulting spectra. Smooth platinum electrodes were electrochemically platinized to produce regular metal island surfaces that led to enhanced absorption of the infrared spectrum of adsorbed carbon monoxide. The infrared spectrum of CO adsorbed from an aqueous electrolyte onto the electrode surface was measured in situ by external reflection spectrometry. The amount of adsorbed CO was estimated from the difference spectrum before and after the CO was oxidized to CO2 by finding the ratio of the absorbance of adsorbed CO prior to oxidation to the absorbance of dissolved carbon dioxide formed when the adsorbed CO was oxidized. By varying the platinization conditions, platinized Pt surfaces that yielded IR band enhancements of up to 20 times that of CO adsorbed on smooth Pt electrodes were prepared. When CO was adsorbed on a smooth Pt electrode, the shape of the band due to the CO stretching mode was quite symmetrical. As the degree of platinization was increased, the band became asymmetrical, then bipolar, and finally appeared as a reflection maximum. This behavior was simulated using the Bergman representation of effective dielectric function.