Self-grown NiCuOx hybrids on a porous NiCuC substrate as an HER cathode in alkaline solution

Abstract

Electrocatalysts converted directly from the substrates hold the key to achieve high catalytic activity and durability due to their high bonding strength, intimate electronic contact, and tunable phase composition. Herein, an electrically conductive porous NiCuC substrate was adopted to develop a multi-porous NiCuOx/NiCuC hydrogen evolution reaction (HER) catalyst using a one-step oxidation method in this research. The NiCuOx hybrids were characterized as three typical layers: an outer layer with NiCuO2 solid solution phase, a partially oxidized intermediate layer, and an inner layer with limited stable oxygen content. The NiCuOx/NiCuC possesses abundant Ni(Ⅱ)-Cu(Ⅱ) sites to accelerate the Volmer step via the electrostatic effect with OH–, numerous metallic NiCu sites to facilitate the H adsorption, and highly accessible channels to promote the Heyrovsky step during HER catalysis. As a result, high electrocatalytic performance was obtained with an overpotential of 116 mV at a current density of 10 mA cm−2 in 1.0 M potassium hydroxide, and a stable catalytic performance during the HER process for more than 24 h.