An Infrared Spectroelectrochemical Study of Cyanide Adsorption on Palladium Surfaces

Role of double-layer cation on the potential-dependent stretching frequencies and binding geometries of carbon monoxide at platinum-nonaqueous interfaces

“…While some differences are noted between vco spectra obtained for CO adlayers on Pt in neutral alkali electrolytes compared with HCIO4 or H2SO4,31 they are ascribably largely to the differing ranges of electrode potential that are accessible in these media.32 More significant alkali cation effects in aqueous media, however, have been observed for thiocyanate adsorption on platinum by means of infrared spectroscopy. 33 It is worth commenting specifically on the present results in relation to the potential-dependent CO binding geometries observed on monocrystalline platinum and rhodium electrodes in aqueous27-32 as well as nonaqueous media.6•7 In large part, the shifts in CO site occupancy from terminal to bridging coordination seen at some of these ordered metal-aqueous systems27•32 occur at markedly higher (i.e., less negative) potentials than the alkalication-induced effects observed in the present work. The former site conversions have been interpreted in terms of the nonspecific effects of electrode potential, with attendant variations in electrode charge and the double-layer field.27•32 Consideration of such surface potential effects upon CO adlayers has enabled some understanding to be reached of the differing behavior of ordered metal surfaces in related electrochemical and uhv systems.27•32 Some more specific effects of the double-layer environment upon these systems, however, have been observed, primarily at lower CO coverages where solvent and/or hydrogen coadsorption can play a role.27•32…”

FTIR Characterization of Surface Interactions of Cyanide and Copper Cyanide with a Platinum Electrode in Alkaline Solution

“…Though there have been numerous studies on the adsorption and oxidation of cyanide on different metals, such as gold, silver, platinum, and palladium, they were undertaken only as a part of descriptions of molecular adsorption from copper-free aqueous solutions. − Only a few studies on the electrochemical processes occurring in copper−cyanide solutions have been published until now, , but they lack information at a molecular level because they relied on information from conventional electrochemical techniques. Thus, specific studies of the adsorption and oxidation of copper cyanide solutions by using spectroelectrochemical techniques are needed.…”