Ni alloy nanowires as high efficiency electrode materialsnfor alkaline electrolysers

Hydrogen production by water electrolysis (WE) is a very promising technologybecause it is a pollution-free process especially if renewable sources areemployed to energy supply. Nowadays, the cost of hydrogen production by WEis higher than other available technologies, which makes WE not competitive.Many efforts have been made to improve WE performance, through the use ofelectrodes made of transition metal alloys as cathode and compound of metaloxide as anode [1].In the field of water-alkaline electrolyzer, the development of cheapnanoporous based nickel electrodes with high electrocatalytic features is one ofthe potential approaches to increase the WE performance [2].A facile method for obtaining nanostructured electrodes is templateelectrosynthesis. Through this method, we have fabricated electrodes formedof Ni nanowires and its alloys that have a very high surface area. In previousworks, we have shown that water-alkaline electrolyzer with Ni nanowireselectrodes covered by nanoparticles of IrO2 as an anode and Pd as a cathodehave good and stable performance also at room temperature [2-5].In this work, the attention has been focused on the fabrication of nickel-alloyelectrodes. Three different alloys (Ni-Co, Ni-Zn and Ni-W) at differentcomposition were studied in order to found the best alloy and relative bestcomposition. Nanostructured electrodes were obtained by templateelectrodeposition using a nanoporous membrane and starting from aqueoussolutions containing the two elements of the alloy at different concentrations.We found that composition of alloys can be tuned by electrolyte compositionand also depends on the difference on the redox potential of elements and onthe presence of complexing agents in deposition bath.The chemical and morphological features of these nanostructured electrodeswill be presented and discussed. Furthermore, electrochemical andelectrocatalytic tests aimed to establishing the best alloy composition werecarried out for both hydrogen and oxygen evolution reaction. Then, testconducted at a constant current density in aqueous solution of potassiumhydroxide (30% w/w) will be also reported. For all investigated alloys we haveobtained very encouraging results.