Electrodeposition of Cobalt Nickel Hydroxide Composite as a High-Efficiency Catalyst for Hydrogen Evolution Reactions

It is challenging but imperative to develop highly efficient, low-cost and environmentally friendly electrocatalysts to produce H2 fuel through water splitting. In order to improve the electrochemical performance of Co-base catalyst for hydrogen evolution reaction (HER), nanoporous cobalt nickel hydroxide (CoNi) composites were fabricated on the 3D nickel foam (NF) by a cyclic voltammetry method. With a doping of nickel hydroxide, the electrocatalytic activity of the catalysts was significantly enhanced. As-prepared optimal CoNi/NF electrode is able to deliver a current density of 10 mA/cm2 with an overpotential (η) of only 77 mV, which is much lower than of Co/NF electrode (185.5 mV) and Ni/NF electrode (189 mV), and shows exceeding stability and durability. The CoNi/NF catalyst also displays extraordinary performance at high current densities (e.g., 200 mA/cm2 at η = 204 mV), and is comparable to the best Co-based HER electrocatalysts reported to date. The high active surface areas (about 14 times higher than the bare NF), high surface wettability and low charge-transfer resistance of CoNi/NF catalyst, together with effective mass transport offered by the 3D nanoporous structure, all contribute to the extraordinary synergistic HER performance.