A crystalline–amorphous interface engineering in Fe-doped NixP electrocatalyst for highly efficient oxygen evolution reaction

Abstract

OER (oxygen evolution reaction) is a critical reaction in several storage and conversion systems for renewable and clean electrochemical energies, including solar fuel devices, metal–air batteries, as well as regenerative fuel and water splitting cells. Regarding the shortcomings of OER, apart from the sluggish kinetics and high reaction overpotential, the reaction rate and overpotential are difficult to be optimized simultaneously. Herein, a novel hierarchical particle–sheet-structured Fe-doped Ni_xP electrocatalyst is developed, which presents abundant interfaces between crystalline particle and amorphous sheet. The OER overpotential is reduced to 204 mV at 20 mA cm⁻² current density, while it is reduced to 225 and 231 mV at 100 and 300 mA cm⁻², respectively. The Fe-doped Ni_xP electrocatalyst also shows fast reaction kinetics, whose Tafel slope is a remarkable 25 mV dec⁻¹. For an electrolytic cell whose cathode and anode are Pt/C/NF and Fe–Ni_xP/NF, respectively, a mere 1.446 V voltage is necessary to drive a 10 mA cm⁻² current density for achieving overall water-splitting property. Notably, it also works stably at considerably high current densities of 500 and 1000 mA cm⁻², representing high potential for commercial applications.