Dissolution of partially immersed nickel during in situ oxidation in molten carbonate: cyclic, stripping and square wave voltammetry measurements

Abstract Electrochemical techniques such as cyclic voltammetry, stripping voltammetry and square wave voltammetry were used to determine the product of concentration and diffusivity of Ni 2+ ions in 62% Li 2 CO 3 +38% K 2 CO 3 electrolyte mixture under standard gas composition(15% O 2 +30% CO 2 ) at 650°C. In the case of cyclic voltammetry and stripping voltammetry, dissolved nickel is first deposited on a gold electrode at negative potentials, then dissolved by scanning through positive potentials. Square wave voltammetry is also used as a more precise method to compare the cD 1/2 product between electrochemical techniques. The magnitude of the peak current from current–potential data is related to scan rate, diffusivity and concentration of nickel ions in the melt. Values of cD 1/2 obtained by these techniques are in good agreement. The saturation concentrations calculated from our measurements (0.5–1 μmol cm 3 ) depend on the diffusion coefficient used in the calculations, but agree with literature values in order of magnitude.