title: Infrared spectroelectrochemical study of dissociation and oxidation of methanol at a palladium electrode in alkaline solution.
abstract: The dissociative adsorption and electrooxidation of CH(3)OH at a Pd electrode in alkaline solution are investigated by using in situ infrared spectroscopy with both internal and external reflection modes. The former (ATR-SEIRAS) has a higher sensitivity of detecting surface species, and the latter (IRAS) can easily detect dissolved species trapped in a thin-layer-structured electrolyte. Real-time ATR-SEIRAS measurement indicates that CH(3)OH dissociates to CO(ad) species at a Pd electrode accompanied by a "dip" at open circuit potential, whereas deuterium-replaced CH(3)OH doesn't, suggesting that the breaking of the C-H bond is the rate-limiting step for the dissociative adsorption of CH(3)OH. Potential-dependent ATR-SEIRAS and IRAS measurements indicate that CH(3)OH is electrooxidized to formate and/or (bi)carbonate, the relative concentrations of which depend on the potential applied. Specifically, at potentials negative of ca. -0.15 V (vs Ag/AgCl), formate is the predominant product and (bi)carbonate (or CO(2) in the thin-layer structure of IRAS) is more favorable at potentials from -0.15 to 0.10 V. Further oxidation of the CO(ad) intermediate species arising from CH(3)OH dissociation is involved in forming (bi)carbonate at potentials above -0.15 V. Although the partial transformation from interfacial formate to (bi)carbonate may be justified, no bridge-bonded formate species can be detected over the potential range under investigation.
authors: Shanghai Key Laboratory of Molecular Catalysis and Innovative Materials, Department of Chemistry, Fudan University, Shanghai 200433, China.
authors: Yao-Yue
authors: YY
authors: Yang
authors: Jie
authors: J
authors: Ren
authors: Han-Xuan
authors: HX
authors: Zhang
authors: Zhi-You
authors: ZY
authors: Zhou
authors: Shi-Gang
authors: SG
authors: Sun
authors: Wen-Bin
authors: WB
authors: Cai
mesh_terms: D055664:Electrochemical Techniques; D004566:Electrodes; D000432:Methanol / Q000737:chemistry*; D010084:Oxidation-Reduction; D010165:Palladium / Q000737:chemistry*; D012972:Sodium Hydroxide / Q000737:chemistry*; D012996:Solutions; D013055:Spectrophotometry, Infrared
chemical_list: D012996:Solutions; D012972:Sodium Hydroxide; D010165:Palladium; D000432:Methanol