Experimental and Theoretical Insights into the Role of Iron in the Rapidly Fabricated Ni/Fe Electrodes for the Oxygen Evolution Reaction.

Abstract

The development of low-cost electrocatalysts for the oxygen evolution reaction (OER) of water electrolysis is crucial for large-scale green hydrogen production. NiFe-based electrocatalysts have garnered significant attention due to their high OER activity; however, the need for a rapid and efficient electrode fabrication method and a clear understanding of the role of Fe in enhancing OER activity remain unresolved. Herein, we developed a highly active NiFe-based OER electrocatalyst self-supported on carbon fiber paper (CFP) using a versatile and rapid thermal shock method, requiring only 30 seconds of heat treatment. The as-prepared Fe1Ni1/CFP shows a current density of 493 mA/cm2 at 1.7 VRHE and a low overpotential of 247 mV at a current density of 10 mA/cm2, with excellent long-term durability in alkaline conditions. In-situ Raman spectroscopy, pH-dependence activity test, and electronic structure calculations revealed that Fe not only promotes the oxidation of adjacent Ni but also accelerates the deprotonation of -OH groups and stabilizes oxo-intermediates, thus displaying both direct and indirect effects and enhancing the overall OER performance. Our study provides a foundation for developing cost-effective electrocatalysts for green hydrogen production and other sustainable energy applications while enhancing our understanding of the role of Fe in NiO catalysts.