Construction of an electrode with hierarchical three-dimensional NiFe-oxyhydroxides by two-step electrodeposition for large-current oxygen evolution reaction

Oxygen evolution reaction (OER) electrocatalysts are promised to be extremely important in hydrogen generation of water electrolysis as one of the renewable energy technologies. However, low efficiency and high cost are two crucial barriers that hinder its development and application. Herein, we developed highly efficient NiFe-based self-supported electrocatalysts by a facile two-step electrodeposition method focusing on the porosification of a nickel foam (NF) substrate. The porous nickel layer (PN/NF) formed in the first step by dynamic hydrogen bubble template electrodeposition proved to be effective in facilitating the mass transfer process, and the following second step of nickel-iron deposition (NiFe/PN/NF) continued to increase the intrinsic catalytic activity, with the two synergistically contributing to the excellent OER performance. As an oxygen evolution electrode, it exhibits high catalytic activity in alkaline water electrolysis, which requires only an overpotential of 211 mV to promote the oxidation reaction of water. The overpotentials for the OER at 100, 500 and 750 mA cm−2 are as low as 244, 297 and 326 mV in 1 M KOH, respectively. In 6 M KOH, the overpotentials for driving electrolytic oxygen production at 100, 500, 750 and 1000 mA cm−2 are even lowered spectacularly to 133 mV, 178 mV, 193 mV and 208 mV, respectively. In particular, the catalyst showed a catalytic stability of more than 40 h at a current density of 500 mA cm−2, which presents it as a highly promising candidate for future large-scale industrial applications.