Electrochemical behaviour of Ni, Cu, Ag, Pt and glassy carbon electrodes in triethylamine-tris(hydrogen fluoride) medium

Abstract.

Voltammetric responses of Ni, Cu, Ag, Pt and glassy carbon (GC) electrodes in triethylamine-tris(hydrogen fluoride) medium in the anodic as well cathodic potential region were investigated. AAS as well as SEM measurements were also made to ascertain the dissolution rate and surface transformation due to fluoride film formation on the electrode surfaces. On Ni, bulk NiF₂ film growth occurs only around 4.0 V following a thin NiF₂ monolayer formation around 0 V. The NiF₂ film shows very little solubility in the medium. Monolayer and bulk CuF₂ phases are formed quite close to each other on Cu during anodic polarization. The anodically formed CuF₂ dissolves to the extent of 12% in this medium. AgF formation follows a different mechanism during the first and subsequent anodic sweeps. The effect of MeCN as well as water addition on the solubility and stability of these fluoride films are also reported. Glassy carbon and Pt electrodes are relatively inert in this medium. Anodic voltammetric responses for other reactive species could be observed only on Pt and GC electrodes. On the cathodic side, all the electrodes show inert behaviour. Electrochemical reduction of PhNO₂, for example, could be observed on all the electrodes.