Effect of Zirconium Substitution in Thiospinel Cobalt-Ferrite Nanoparticles Decorated over Nitrogen-Doped Graphene Oxide Sheet as an Oxygen Evolution Reaction Electrocatalysts

Abstract

The oxygen evolution reaction performance of spinel cobalt iron sulfide (CoFe₂S₄) is constrained by its inferior charge transfer capabilities compared to RuO₂. Herein, partial substitution of zirconium (Zr⁴⁺) into the octahedral Fe site of CoFe₂S₄ is explored to enhance its electrocatalytic performance. The structural and electronic characterization reveals that Zr⁴⁺ incorporation induces lattice distortion and modulates the electronic environment, resulting in an enhanced charge distribution. Notably, the optimized Zr-doped catalyst (Zr_0.1CFS/N-RGO) exhibits a significantly improved oxygen evolution reaction performance, achieving a low overpotential of 470 mV at 10 mA cm⁻² and a small Tafel slope of 55 mV dec⁻¹ in 1 M KOH. Furthermore, the catalyst demonstrates remarkable durability, retaining 91% of its initial current density after 12 h of continuous operation. These findings underscore the potential of strategic transition metal doping to optimize nonprecious metal-based catalysts for sustainable electrochemical water splitting applications.