Fe‐Doped Nickel Hydroxide/Nickel Oxyhydroxide Function as an Efficient Catalyst for the Oxygen Evolution Reaction

Abstract Designing metal hydroxide electrocatalysts with high efficiency to overcome the slow reaction kinetics of the oxygen evolution reaction (OER) is considered as a significant approach for renewable energy resources. We report here a simple methodology to synthesize 2D thin nickel hydroxide/nickel oxyhydroxide sheets that show efficient activity towards OER. Further, by doping with a heteroatom, Fe, thinner sheets of nickel hydroxide/nickel oxyhydroxide are developed, which exhibit enhanced electrocatalytic activity towards OER with high durability. Fe‐doped Ni(OH) 2 /NiOOH requires only 200 mV overpotential to produce 10 mA/cm 2 , whereas bare Ni(OH) 2 /NiOOH needs 290 mV overpotential. Moreover, Fe‐doped nickel hydroxide/nickel oxyhydroxide shows a minimal Tafel value of 48 mV/decade, which is even lower than RuO 2 /CC (82 mV/decade). X‐ray photoelectron spectroscopy indicates that in the case of Fe‐doped Ni(OH) 2 /NiOOH, the Ni 3+ signal enhances, which indicates the favourable stabilization of Ni 3+ in the presence of Fe 3+ dopant. Under electrochemical OER conditions, in Fe‐doped Ni(OH) 2 /NiOOH, Fe 3+ species help to generate more Ni 3+ , which function as the active species. Fe 0.06 Ni 0.94 (OH) 2 /NiOOH shows long‐term stability for at least 24 hours in alkaline medium. This work unveils a green strategy for Fe‐doping in 2D thin sheets of Ni(OH) 2 /NiOOH, which show improved electrocatalytic activity compared to bare Ni(OH) 2 /NiOOH. The mechanism of OER activity enhancement after Fe‐doping is proposed here.