Heterogeneous S-NiFe2O4@NiSe2 nanospheres for oxygen evolution reaction with long-term stability

Abstract

Electrochemical water splitting is a potential and green approach to produce a large amount of hydrogen. However, its half reaction, the oxygen evolution reaction suffers sluggish dynamics and huge overpotential. This immensely encumbers the energy conversion efficiency from electric energy to hydrogen energy, resulting in cost increase. Besides, rare metal catalysts such as RuO2 and IrO2 has high OER catalytic activity but they are low in reserves and expensive. So it is of great significance to explore highly efficient, stable and cheap transition metal based electrocatalysts to speed up OER rate. Herein, S doped NiFe2O4@NiSe2 nanospheres supported on nickel foam are synthesized through a simple one-pot hydrothermal method. Thanks to the unique structure, large surface area, numerous active sites, incorporation of S-anion atoms and synergistic effect between different components, S doped NiFe2O4@NiSe2 nanospheres show extraordinary efficient electrocatalytic activity towards OER in alkaline medium. While the current density is 10 mA cm-2, the OER overpotential is 190 mV. Meanwhile, it exhibits excellent long-term stability and keeps at 10 mA cm-2 for at least 94 hours in chronopotentiometry test.