Adsorption of atomic hydrogen on a polycrystalline Pt electrode surface studied by FT-IRAS: the influence of adsorbed carbon monoxide on the spectral feature

• Published in: Journal of electroanalytical chemistry (Lausanne, Switzerland) Vol. 485; no. 2; pp. 128 - 134
• Main Authors: Nanbu, Noritoshi, Kitamura, Fusao, Ohsaka, Takeo, Tokuda, Koichi
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 12.05.2000
• Subjects: Adsorption of carbon monoxide; Adsorption of hydrogen; Hydrogen evolution reaction; IRAS; Platinum electrode; Adsorption of carbon monoxide; IRAS; Platinum electrode; Hydrogen evolution reaction; Adsorption of hydrogen
• ISSN: 1572-6657; 1873-2569
• DOI: 10.1016/S0022-0728(00)00104-2

Adsorption of atomic hydrogen on a polycrystalline Pt electrode surface was studied by in situ infrared reflection absorption spectroscopy (IRAS). When the electrode potential was adjusted in a potential range where the underpotential-deposited (upd) hydrogen was formed, an absorption band assignable to the vibration of on-top CO (which would be formed by the reduction of a trace of CO 2) appeared at ca. 2010 cm −1 even for highly purified 0.1 M (M=mol dm −3) H 2SO 4 solution. An absorption band due to the on-top H was observed at ca. 2070 cm −1 for a conventional acidic solution in a potential range as narrow as ca. 0.1 V just before the hydrogen evolution reaction (her) ascribable to the reduction of hydronium ions began. On the other hand, the on-top H band was observed unequivocally for a solution containing 1 mM H 2SO 4 and 99 mM Na 2SO 4 over a wide potential range where molecular hydrogen was formed by the reduction of hydronium ions. Even for a neutral solution such as 0.1 M KCl, the weak band ascribable to the on-top H was detected. The dependence of the spectral feature on the concentration of hydronium ions and the applied electrode potential strongly suggested that the on-top H is the intermediate in the electrochemical reduction of hydronium ions. We demonstrated that the adsorbed CO is readily formed by the reduction of CO 2 in the 0.1 M H 2SO 4 solution.