Interface engineering: Enhancing the electrocatalytic activity of heterostructure NiFe-based alloy over valorized carbon waste towards water splitting

Abstract

Using cost-effective bifunctional electrocatalysts is a labor-saving approach to generating green hydrogen via accelerating kinetics for anodic and cathodic reactions, thus advancing the overall competence of water splitting. Herein, a facile electrodeposition approach, i.e., dynamic hydrogen bubble template (DHBT), is adopted to fabricate Ni–Fe-binary alloys at the surface of a wasted graphite rod (WGR) which is pre-treated via electrochemical oxidation in 1 M H₂SO₄ solution to bloom the surface properties, i.e., increase its hydrophilicity, surface roughness, and degree of exfoliation. Various analyses are applied to characterize the fabricated catalysts such as SEM, mapping EDX, TEM, XRD, XPS, and Raman tests. Linear sweep voltammetry (LSV) is used to probe the outstanding catalytic activity of NiFe/WGR towards both the oxygen and the hydrogen evolution reactions (OER) and (HER), respectively. It displays η@10 mA cm⁻² of −77, and 283 mV for HER, and OER, respectively. NiFe/WGR as a bifunctional electrocatalyst presents a low cell voltage of 1.6 V at a current density of 10 mA cm⁻² with insignificant change over a prolonged electrolysis time (24 h). This work shows the design of a profitable catalyst characterized by being active, stable, and bifunctional toward overall water splitting.