Highly active NiMo foam-based electrocatalysts for the hydrogen evolution reaction in alkaline media

Abstract

The design of non-noble electrocatalysts is the foremost approach to overcome the scarcity, and the high cost of the benchmark catalysts applied to the hydrogen evolution reaction (HER) in alkaline media for the green H2 generation. Nevertheless, electroactive arrays based on transition metals and with an outstanding faradaic and ionic performance to HER are unusual, or their electrochemical properties are not adequately scrutinized. In this sense, an easy two-step route is described to improve the catalytic performance of the commercial Ni foam electrodes. As the first step, an ultrasound-assisted chemical treatment allows obtaining regularly cracked and high electroactive catalysts. Subsequently, the surface is decorated with NiMo-based nanostructures, and consequently, the active-site density is increased, the overpotential is decreased and the HER is raised. Regarding the last, NiMo80/NiFA reports the lowest overpotential of 18 mV at 4 μA mbar−1, and the Heyrovsky mechanism as rate-determining step towards the HER. In this sense, differential electrochemical mass spectrometry (DEMS) is employed to elucidate the onset potential, kinetics, and mechanism of the HER at catalysts in an alkaline medium.