Iron-doped nickel cobalt oxide nanorods composited with nitrogen and sulfur co-doped reduced graphene oxide for electrocatalytic oxygen evolution reaction

Abstract

Developing a cost-effective and highly active electrocatalyst for the oxygen evolution reaction (OER) remains a key factor in advancing sustainable energy conversion technologies. Nickel cobaltite (NiCo₂O₄) with its availability of redox couples and stable spinel structure stands out as an effective OER electrocatalyst. While the low conductivity and limited surface area restricts their use. To resolve the addressed issues, our work focuses on doping Fe in NiCo₂O₄ as an efficient way to modulate the electronic structure leading to enhanced electrical conductivity and the incorporation of nitrogen and sulfur co-doped reduced graphene oxide which would increase the surface area and durability of nickel cobalt oxide. Herein, we designed a Fe doped nickel cobalt oxide nanorods composited with N,S-rGO by a hydrothermal method followed by calcination. The prepared electrocatalyst with overpotential of 300 mV at current density of 10 mA/cm² in 1 M KOH exhibited 65 h stability. The improved catalytic activity at the presence of Fe³⁺ sites in nickel cobaltite would enhance charge and electron transfer pathways. This doping tends to induce the formation of highly active oxidation states of Co³⁺ and Ni³⁺ thus maximizing the formation of NiO and CoO bonds which enhances the adsorption and desorption of OER intermediates. Therefore, Fe doped nickel cobalt oxide composited with a co-doped reduced graphene oxide could be a promising, efficient, and durable OER electrocatalyst in alkaline medium.