Ternary duplex FeCoNi alloy prepared by cathode plasma electrolytic deposition as a high-efficient electrocatalyst for oxygen evolution reaction

Developing multi-transitional metal electrocatalysts via a facile, rapid and cost-effective approach to achieve highly catalytic activity and long-term durability remains challenging. Herein, a novel cathode plasma electrolytic deposition (CPED) technology is successfully applied to directly fabricate ternary noble metal-free FeCoNi alloys with duplex phases on 304 stainless steel substrate as self-supporting electrocatalysts for oxygen evolution reaction (OER). Effects of the CPED technical parameters on the microstructure, morphology, and electrochemical properties of ternary FeCoNi alloys are systematically investigated by a series of orthogonal experiments. The as-received FeCoNi alloy, composed of duplex phases (i.e. face-centered cubic and body-centered cubic), is found to be able to achieve a current density of 10 mA cm⁻² at an overpotential of 285 mV in 1 M KOH electrolyte with a Tafel slope of 42 mV dec⁻¹, and long-term stability. This work provides a new way to synthesize multi-component electrocatalysts for energy storage and conversion in a large scale base for practical commercialization.