Two-Step Electrodeposition of Co/NiFe–OH Nanosheets on Ni Foam for Highly-Efficient Alkaline Hydrogen Evolution

The development of efficient and stable non-noble metal-based electrocatalysts is crucial in large-scale water electrolysis for hydrogen production. Among various non-noble metal-based electrocatalysts, NiFe layered-double hydroxide has been attracting extensive interest due to its tunable electronic structure and abundant active sites. However, its hydrogen evolution (HER) performance is constrained by its poor intrinsic conductivity and low accessibility of the active sites. To solve these shortcomings, a two-step electrodeposition strategy was adopted in this work to successfully construct a Co/NiFe–OH nanosheet array on nickel foam (labeled as Co/NiFe–OH/NF). First, a Co/Co(OH) 2 nanosheet array was electrodeposited on NF as a highly conductive backbone, then Ni(OH) 2 /FeOOH (NiFe–OH) composite nanosheets were electrodeposited on the Co/Co(OH) 2 nanosheet array surface. This unique design allows the prepared electrocatalyst to exhibit excellent HER properties. In 1 M KOH, the Co/NiFe–OH/NF only required an overpotential of 18 mV at a current density of −10 mA cm –2, and exhibited excellent long-term stability of more than 250 h at −200 mA cm –2, significantly outperforming the comparison samples. Interestingly, the present catalyst also demonstrated excellent electrocatalytic HER activity in harsh conditions, including simulated seawater and 3 M KOH, using natural water and distilled water as the solvent, respectively.