Hybrid electrocatalyst of CoFe₂O₄ decorating carbon spheres for alkaline oxygen evolution reaction

The exploration of highly effective, durable, and affordable electrocatalysts for the oxygen evolution reaction (OER) is vital in developing an alkaline electrolyzer for H₂ generation. Although binary transition metal oxides, particularly spinel ferrites with a general chemical formula MFe₂O_4, are a promising class of candidates for OER, their intrinsically low electrical conductivity has a significant negative impact on their electrochemical performances. Herein, we report a simple one-step method for tailoring carbon spheres (CSs) with CoFe₂O₄ (CFO) to form a CFO@CSs composite as a cost-effective electrocatalyst. The as-synthesized CFO@CSs features a high specific surface area of 56.94 m²/g and exhibits decently high OER catalytic activity with a relatively small overpotential of 390 mV at 10 mA/cm², fast kinetics, and high durability in alkaline medium. Moreover, the pairing of the bare Ni mesh electrode as the cathode and the CFO@CSs on Ni mesh as the anode is set up to illustrate its feasibility for the overall alkaline water splitting. This study offers a cost-effective electrocatalyst for OER that can be used instead of precious metals in various renewable energy storage and conversion applications.