Facile synthesis of Fe/Ni bimetallic oxide solid-solution nanoparticles with superior electrocatalytic activity for oxygen evolution reaction

The sluggish oxygen evolution reaction (OER) is an important half-reaction of the electrochemical water-splitting reaction. Amorphous Fe/Ni composite oxides have high activity. In this work, we modified the aerosol spray-assisted approach and obtained amorphous Fe-Ni-O _x solid-solution nanoparticles (Fe-Ni-O _x -NPs) approximately 20 nm in size by choosing iron/nickel acetylacetonates as raw materials instead of inorganic salts. The small-sized Fe-Ni-O _x -NPs were characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD) analysis, energy-dispersive X-ray spectroscopy (EDX), and X-ray photoelectron spectroscopy (XPS). Furthermore, an investigation of electrochemical OER performance suggests that the small-sized Fe-Ni-O _x -NPs have higher activity than the large-sized Fe-Ni-O _x -MPs. A small overpotential of 0.315 V was demanded to obtain a working current density of 50 mA/cm², and the Tafel slope was as low as 38 mV/dec.