Laser-nanostructured Ni-Fe electrodes for improved supercapacitor-electrolysers systems

Abstract

There is an increasing interest in developing an Ni-Fe supercapacitor-electrolyser system (SCES) for electricity storage and efficient hydrogen production. In this study, periodic nanostructures on nickel [(λNi = 570 ± 30) nm] and on iron sheets [(λFe = 553 ± 6) nm] have been fabricated and were used as electrodes in an alkaline SCES. Their efficiency was compared to untreated nickel and iron sheets. The electrochemical evaluation of the nanostructured electrodes showed lower overpotential (η10 and η100) and lower Tafel slope for the hydrogen evolution reaction (HER) and oxygen evolution reaction (OER). The hydrogen production efficiency of the laser-nanostructured electrodes was significantly enhanced. Moreover, the laser-nanostructured electrodes' double-layer capacitance (CDL) values were increased 1.5 times for laser-nanostructured Fe electrodes and 5.3 times for laser-nanostructured Ni electrodes. These results show the potential of the fabricated electrodes in applications serving a dual purpose, i.e., enhanced hydrogen production and increased charge storage.