Precipitation/dissolution equilibrium to achieve trace iron doping on the surface of β-Ni(OH)2 for electrocatalytic oxygen evolution

Abstract

Nickel-iron bimetallic oxygen/hydroxide has become the benchmark for non-noble metal oxygen evolution reaction catalysts, but the challenge remains to maximize the density of Fe sites on the surface of nickel-based materials while improving the utilization rate of iron. Herein, Fe doped β-Ni(OH)2/NF with three-dimensional (3D) hybrid structure is synthesized by a facile two-step hydrothermal design. The doping of trace iron on the surface of β-Ni(OH)2 was achieved by precipitation/dissolution equilibrium while maintaining the order of the β-Ni(OH)2 matrix. The 3D hybrid structure provides more sites for iron incorporation on the surface/edge/corner of β-Ni(OH)2 host by precipitation/dissolution equilibrium doping mode. The addition of iron on the surface can expose more Fe-Ni-Fe sites, adjust the electronic structure of nickel sites, and optimize the adsorption/analytical energy of OER reaction intermediates. As expected, Fe2(0.1)-β-Ni(OH)2/NF demonstrates optimal OER catalytic activity, with only 300 mV overpotential at 100 mA cm−2 current density and a small Tafel slope up to 44.0 mV dec-1. Its morphology and OER performance present inconspicuous decay after 72 h of stable operation at 100 mA cm−2 current density. This paper provides a feasible path for the design and synthesis of trace doped bimetallic OER catalysts with high efficiency and stability.