Atomic-scale topochemical preparation of crystalline Fe3+-doped β-Ni(OH)2 for an ultrahigh-rate oxygen evolution reaction

Abstract

The development of highly efficient and affordable electrocatalysts for the sluggish oxygen evolution reaction (OER) has been considered as a great challenge to the practical applications for water splitting and in rechargeable metal–air batteries. Herein, we report active and robust OER catalysts of Fe³⁺-doped β-Ni(OH)₂ prepared via an atomic-scale topochemical transformation route. Based on the premise that all Fe³⁺ is incorporated into the β-Ni(OH)₂ lattice, the OER activity increases directly with the content of Fe³⁺. The Fe(0.5)-doped β-Ni(OH)₂ catalyst affords a current density of 10 mA cm⁻² at an overpotential as low as 0.26 V and a small Tafel slope of 32 mv dec⁻¹. Comparing the state-of-the-art IrO₂ catalyst, the Fe(0.5)-doped β-Ni(OH)₂ catalyst exhibits higher activity and stability from galvanostatic tests at 10 mA cm⁻². Additionally, we experimentally demonstrate that Fe(0.5)-doped β-Ni(OH)₂ exerts higher OER activity than Fe(0.5)-doped α-Ni(OH)₂. All evidence indicates that Fe and the β-Ni(OH)₂ matrix play an important role in NiFe-based catalysts.