Voltammetric and spectroscopic characterization of cyanide adlayers on Pt(h,k,l) in an acidic medium

Abstract

Irreversibly adsorbed cyanide adlayers formed on single-crystal platinum electrodes were studied by cyclic voltammetry and in-situ FTIR spectroscopy in a perchloric medium. A vibrational band around 2100 cm−1 was assigned to the C-N stretching vibration of adsorbed cyanide on the three electrode surfaces. Cyanide adlayers seem to be stable on Pt(111) in a wide range of potentials. Tuning rates of 100 and 30 cm−1 V−1 were measured for the band at 2100 cm−1 below and above 0.5 V, respectively. Adsorbed cyanide has a complex behavior on Pt(100). The polarization of the cyanide-covered Pt(100) electrode in the potential region below 0.4 V (RHE) leads to the formation of a CO adlayer (band at 1820 cm−1). The oxidation of adsorbed cyanide on the Pt(100) electrode produces CO2 (band at 2344 cm−1) and adsorbed NO (band at 1624 cm−1), which shows a characteristic voltammetric behavior. Adsorbed cyanate (band at 2175 cm−1) was also identified as an intermediate product during adsorbed cyanide oxidation on Pt(100). Finally, for Pt(110), adsorbed cyanide is slowly desorbed below 0.1 V (RHE).