Electrocatalytic behavior of Ni-Co-Fe₃O₄ nanospheres for efficient oxygen evolution reaction

Herein, a simple hydrothermal approach has been used to synthesize nickel and cobalt co-doped ferric oxide (Ni-Co-Fe₃O₄) nanospheres and tested for electrocatalytic oxygen evolution reaction (OER). The different characterization outcomes verify the successful co-doping of Ni and Co into Fe₃O₄. The as-synthesized Ni-Co-Fe₃O₄ nanospheres demonstrated better electrochemical properties as compared to its counterparts Fe₃O₄, Co-Fe₃O₄, and Ni-Fe₃O₄. At a define current density of 10 mA cm⁻², the Ni-Co-Fe₃O₄ electrocatalyst obtained a smaller overpotential of 243 mV and the tafel value of about 54.84 mV dec^-1. In addition, Ni-Co-Fe₃O₄ acquired efficient electrochemical stability for 25 h duration reaching current density of 10 mA cm⁻² in 1 M potassium hydroxide solution. Furthermore, it is determined that the outstanding electrocatalytic OER activity of the prepared material as a result of its distinct morphology. Analyses using the density functional theory revealed that less hydroxyl ions adhesion energy is very beneficial for the OER of crystalline Ni-Co-Fe₃O₄ nanospheres. The least adhesive energy for adsorption of hydroxyl ion at the top of the Fe atom in Ni-Co-Fe₃O₄ further confirmed their outstanding results in improving electrocatalytic OER performance. Our work gives a decent option for future transition metal oxides based electrode nanomaterials for water electrolysis applications.