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Combined Surface-Enhanced Infrared Spectroscopy and First-Principles Study on Electro-Oxidation of Formic Acid at Sb-Modified Pt Electrodes

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journal contribution
posted on 25.02.2010, 00:00 by Bin Peng, Hui-Fang Wang, Zhi-Pan Liu, Wen-Bin Cai
In situ electrochemical surface-enhanced infrared absorption spectroscopy (EC-SEIRAS) together with a periodic density functional theory (DFT) calculation has been initially applied to investigate the mechanism of formic acid electro-oxidation on Sb-modified Pt (Sb/Pt) electrode. EC-SEIRAS measurement reveals that the main formic acid oxidation current on Sb/Pt electrode is ca. 10-fold enhanced as compared to that on clean Pt electrode, mirrored by nearly synchronous decrease of the CO and formate surface species, suggesting a “non-formate” oxidation as the main pathway on the Sb/Pt electrode. On the basis of the calculations from periodic DFT, the catalytic role of Sb adatoms can be rationalized as a promoter for the adsorption of the CH-down configuration but an inhibitor for the adsorption of the O-down configuration of formic acid, kinetically facilitating the complete oxidation of HCOOH into CO2. In addition, Sb modification lowers the CO adsorption energy on Pt, helps to mitigate the CO poisoning effect on Pt.