Fabrication of nanostructured Ni-Co electrodes for hydrogen and oxygen evolution reaction in water-alkaline electrolyzer

Abstract

Template electrosynthesis is a facile and cheap approach for obtaining nanostructures with very high surface area. This fabrication method has been used to produce electrodes for different applications, among which the electrolysis. In previous works, Ni and IrO2 nanostructured electrodes were tested for hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) in alkaline solution, respectively, without and with addition of Pd nanoparticles. In this work, Ni-Co alloy electrodes were fabricated by the same method, starting from a bath containing a mixture of Ni and Co. After fabrication of the nanostructures and template dissolution, electrodes were characterized by EDS and SEM. The results show that i) alloy deposition is possible by this method, and ii) alloy is richer in Co compared to the composition of the bath employed for deposition. In order to evaluate the electrocatalytic properties of Ni-Co electrode, electrochemical tests were performed and the results were compared with pure Ni and Co electrodes. The tests were conducted through either cyclic or linear sweep voltammetry in 30% w/w KOH aqueous solution at room temperature. For the HER, pure Ni electrode was found to be more performing. Whereas, with regard to the OER, performance of the nanostructured Ni-Co electrodes show an improvement more than 20% in terms of electrocatalysis, in comparison with pure Ni and Co electrodes.