CN-和SCN-水溶液中Cu电极上膜的形成及其结构的非现场红外反射吸收光谱研究

本文用电化学方法和非现场红外反射吸收光谱方法研究了CN^-和SCN^-水溶液中Cu电极上膜的形成及其结构,对于0.5mol·l^-1NaSCN+0.5mol·l^-1NaF/Cu体系,在-0.50到0.20伏(相对SCE)范围内形成的表面膜给出2157～2162cm^-1的红吸收峰;在-0.20至0.40伏则得到2177cm^-1峰。这表明在不同电势下生成的硫氰化铜表面膜的结构不同,对于0.5mol·l^-1NaCN+0.5mol·l^-1NaF/Cu体系,在0.00至0.40伏电势范围内,可得到两个吸收峰,波数分别为2128和2170cm^-1,对应于Cu(CN)₂^-和CuCN,此二峰强度基本同步地随电势改变,表明不同电势下表面膜的结构基本相同。

EX-SITU FTIR REFLECTION-ADSORPTION SPECTROSCOPIC STUDIES OF SURFACE FILMS ON COPPER ELECTRODE FORMED IN CYANIDE AND THIOCYANATE SOLUTIONS

The surface films potential-statically formed on Cu electrode in 0.5mol·l^-1 NaNCS+0.5mol·l^-1NaF(A) and 0.5mol·l^-1 NaCN+0.5mol·l^-1NaF (B) were sudied using ex-situ FTIR reflection adsorption spectroscopy. For the surface films formed in solution A, two bands were obtained at wavenumber 2177 and 2157-2162 cm^-1. These two bands showed different dependence on the potential at which they had been found, indicating changes in film composition and structure with potential. On the contrary, the two bands 2170 and 2128 cm^-1 found for the surface films formed in solution B exhibited similar potential dependence, implying an approximately constant film composidon. The disappearance of IR bands at higher potentials for both solutions A and B was attributed to the oxidation of CN and NCS groups.