Formic acid electrooxidation on Pd in acidic solutions studied by surface-enhanced infrared absorption spectroscopy.
A mechanistic study of electrocatalytic oxidation of formic acid on Pd in sulfuric and perchloric acids is reported. Surface-enhanced infrared absorption spectroscopy in the attenuated total reflection mode (ATR-SEIRAS) shows the adsorption of CO, bridge-bonded formate, bicarbonate, and supporting anions on the electrode surface. Poisoning of the Pd surface by CO, formed by dehydration of formic acid, is very slow and scarcely affects formic acid oxidation. The anions are adsorbed more strongly in the order of (bi)sulfate > bicarbonate > perchlorate, among which the most strongly adsorbed (bi)sulfate considerably suppresses formic acid oxidation in the double layer region. The oxidation is suppressed also at higher potentials in both acids by the oxidation of the Pd surface. Adsorbed formate is detected only when formic acid oxidation is suppressed. The results show that formate is a short-lived reactive intermediate in formic acid oxidation and is hence detected when its decomposition yielding CO(2) is suppressed. The high electrocatalytic activity of Pd can be ascribed to the high tolerance to CO contamination and also high catalytic activity toward formate decomposition.
National Institute of Advanced Industrial Science and Technology, Higashi 1-1-1, Central 5, Tsukuba, Ibaraki 305-8565, Japan.
Hiroto
H
Miyake
Tatsuhiro
T
Okada
Gabor
G
Samjeské
Masatoshi
M
Osawa
D000143:Acids / Q000737:chemistry*; D002245:Carbon Dioxide / Q000737:chemistry; D002248:Carbon Monoxide / Q000737:chemistry; D011211:Electric Power Supplies; D004563:Electrochemistry; D004566:Electrodes; D005561:Formates / Q000737:chemistry*; D010084:Oxidation-Reduction; D010165:Palladium / Q000737:chemistry*; D010472:Perchlorates / Q000737:chemistry; D013055:Spectrophotometry, Infrared / Q000379:methods; D013464:Sulfuric Acids / Q000737:chemistry; D014867:Water / Q000737:chemistry
D000143:Acids; D005561:Formates; D010472:Perchlorates; D013464:Sulfuric Acids; D014867:Water; C030544:formic acid; D002245:Carbon Dioxide; D010165:Palladium; D002248:Carbon Monoxide; C033158:sulfuric acid