Preparation, characterization, and application of alkaline leached Ni/Zn–Ni binary coatings for electro-oxidation of methanol in alkaline solution

Abstract

The Ni–Zn binary coating was electrochemically deposited on a copper electrode. Then, it was etched in a concentrated alkaline solution (30 wt% NaOH) to obtain a porous electrocatalytic surface suitable for methanol electro-oxidation in alkaline solution. The surface compositions of coatings before and after alkaline leaching were determined by atomic absorption spectroscopy and energy dispersive X-ray analysis. The surface morphologies were investigated by scanning electron microscopy. It was found that the leached Ni–Zn coating has a porous structure. Electrocatalytic activity toward the methanol electro-oxidation was assessed by cyclic voltammetry and electrochemical impedance spectroscopy techniques. The activation of electrode related to the removal of existing corrosion products and formation of pores and cracks during alkaline leaching. Cyclic voltammetry studies confirmed that the alkaline leaching process improved the activity of Ni–Zn coating in comparison with smooth Ni deposit for the methanol electro-oxidation.