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.

Automated summary

In this study, Ni-Co-Fe3O4 nanospheres were synthesized via a simple hydrothermal approach and evaluated as electrocatalysts for the oxygen evolution reaction (OER). Characterization confirmed the successful co-doping of Ni and Co into Fe3O4. The Ni-Co-Fe3O4 nanospheres exhibited enhanced electrochemical properties compared to Fe3O4, Co-Fe3O4, and Ni-Fe3O4. At a current density of 10 mA cm-2, the Ni-Co-Fe3O4 electrocatalyst showed a lower overpotential of 243 mV and a tafel value of 54.84 mV dec-1. Additionally, Ni-Co-Fe3O4 demonstrated excellent electrochemical stability in 1 M potassium hydroxide solution for 25 hours. The outstanding OER activity of Ni-Co-Fe3O4 can be attributed to its unique morphology and lower hydroxyl ion adhesion energy. This research provides a promising option for future electrode nanomaterials based on transition metal oxides for water electrolysis applications.