NiFeOxHy/Ni3Fe interface design via electropassivation for superior catalysis of HER

Herein, a novel tailor-tuned NiFeOxHy/Ni3Fe catalyst is introduced for use as an efficient cathode for the hydrogen evolution reaction (HER). It shows a marked electrocatalytic activity among several NiFe-based catalysts approaching those of noble-metal-based catalysts. That is, low overpotentials of −70 mV and −196 mV are enough to drive 10 mA cm–2 and 100 mA cm–2, respectively, of hydrogen generation in 1.0 M KOH. A foam-like film of Ni3Fe alloy is electrodeposited using the dynamic hydrogen bubble template (DHBT) method and shows a reasonable HER activity by delivering 10 mA cm–2 at −190 mV. Ni3Fe alloy is subsequently electropassivated by controlled repetitive cycling of potential in 1.0 M KOH solution to create NiFeOxHy/Ni3Fe interfaces, so a fast water cleavage occurs during HER boosting the overall rate. The electropassivation treatment is proven a successful technique to develop such metal/oxygenated metal junctions for improved HER kinetics in alkaline media. Various physicochemical analysis techniques such as XRD, SEM, EDS-mapping, ICP-OES, and XPS are employed to characterize the designed catalysts. The proposed NiFeOxHy/Ni3Fe catalyst layer is among the promising earth-abundant catalytic materials used for the electrolytic production of hydrogen in alkaline media.