Abstract
The corrosion of a nickel electrode in aqueous cyanide solutions has been investigated by subtractively normalised interfacial Fourier-transform infrared spectroscopy (SNIFTIRS). At potentials more cathodic than 200 mV vs. SCE, only [Ni(CN)4]2– was detected. Cyanide was oxidised to cyanate (OCN–) and then successively to carbon dioxide at potentials more anodic than 200 mV vs. SCE. Features were assigned to HCN (2094 cm–1) and HNCO (2256 cm–1) and their formation was attributed to pH changes associated with the oxidation of cyanide to cyanate, and the decomposition of cyanate (to CO2 and NH3). The appearance of a band at ca. 2218 cm–1 in IR spectra of the thin layer at very high anodic potentials (> 1000 mV vs. SCE) was believed to arise from an unstable nickel(II) isocyanate complex.
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