Electrochemically engineered domain: nickel–hydroxide/nickel nitride composite for alkaline HER electrocatalysis

Abstract

Boosting hydrogen evolution reaction (HER) performance in alkaline media has been a topic of interest in a world that continuously strives for cleaner energy conversion systems. The paucity of protons provides a challenge to performing the HER in an alkaline environment and is a major impediment to decreasing the energy requirement needed to produce hydrogen. Here, we improve the HER activity of nickel-nitride by electrochemically anodizing the surface which aids water dissociation in alkaline HER. We experimentally show that by oxidizing the nickel nitride on a nickel foam (Ni₃N/NF) surface using cyclic voltammetry (CV) cycles in Fe-unpurified KOH media, Ni₃N can be converted to a Ni(OH)₂/Ni₃N composite. Activation of the Ni₃N/NF with 50 CV cycles resulted in a low HER overpotential of 172 and 207 mV at the current densities of 50 and 100 mA cm⁻², respectively. The 50 CV cycle Ni₃N/NF also had the minimum charge transfer resistance at 6 Ω compared to all other prepared samples, and the Tafel slope is 100.87 mV dec⁻¹.