Iron nickel sulphide embedded on multi-walled carbon nanotubes as efficient electrocatalysts for oxygen evolution reaction in alkaline medium

Abstract

Oxygen evolution reaction (OER) plays a vital role in clean energy production such as water splitting and metal-air batteries to achieve renewable energy technologies. In this regard, electrocatalysts play a major role in the oxidative half-cell reaction of water splitting. Among various transition metal-based catalysts, FeNi-based electrocatalysts are of particular interest owing to their low-cost, non-toxic, non-precious metal, high stability, and enhanced electrocatalytic performance of OER. Herein, we report the preparation of iron-nickel sulphide-based catalysts (a mixed phase of Fe5Ni4S8 and Ni9S8, or FeNiS) and their composite with MWCNTs using a facile hydrothermal method for electrocatalytic water oxidation. The physicochemical properties of the prepared composite of FeNiS-MWCNT were analyzed through various characterization techniques. The FeNiS-MWCNT composite exhibits enhanced electrochemical performance of OER with the current density of 10 mA cm−2 at a lower overpotential of 260 mV vs RHE and lower Tafel slope of 50 mV dec−1 as compared to FeNiS (10 mA cm−2 at an overpotential of 370 mV vs RHE; Tafel slope of 82 mV dec−1). The superior electrocatalytic performance of the FeNiS-MWCNT composite over the FeNiS catalyst is attributed to the higher surface area, conductivity of the MWCNT and the synergistic effect of FeNiS and MWCNTs. This work also paves the way for the development of highly efficient and promising non-precious metal catalysts for electrocatalytic water oxidation as an alternative to traditional noble-metal catalysts.