Electrochemical Formation of Porous Nickel in Zinc Chloride-Alkali Chloride Melts

Abstract

An electrochemical method of preparing a porous nickel electrode by alloy formation and subsequent dealloying in zinc chloride-alkali chloride melts at was studied. X-ray diffraction measurements at different stages of dealloying suggested that two step transformation from γ- to - and from - to alloy occurred. Dealloyed material exhibited well-developed porous structure of hundreds of nanometers in size. Electron probe microanalysis of a partially dealloyed layer showed that the dissolution of zinc occurred relatively uniformly throughout the alloy layer. Scanning electron microscopy of samples obtained at different temperatures showed that the size of porous structure (crevices and pores) was smaller at lower temperatures. The porous nickel electrode showed relatively low overvoltages in the hydrogen evolution reaction in aqueous solution.