Durable and Stable Bifunctional Co₃O₄-Based Nanocatalyst for Oxygen Reduction/Evolution Reactions

The oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) are recognized as the core reaction processes in regenerative energy storage and conversion systems. The design of cost-effective and high-performance bifunctional ORR/OER electrocatalysts (ECs) is very important for their substantial commercialization. Herein, sponge-like Co 3 O 4 nanoparticles anchored on carbon (Sp-Co 3 O 4 /C) are successfully fabricated by a facile two-step solvothermal strategy for ORR/OER in an alkaline electrolyte. The Sp-Co 3 O 4 /C EC exhibits promising bifunctional ORR/OER activity with ORR onset potential ( E onset = 0.88 V vs RHE), half-wave potential ( E 1/2 = 0.75 V), limiting current density ( j = −6.60 mA cm –2 ), OER onset potential ( E onset = 1.26 V), and OER overpotential for 10% energy conversion (η 10 = 0.38 V) in 0.1 M KOH. It demonstrates a significantly lower reversibility index (Δ E = E j 10 – E 1/2 = 0.86 V), comparable to standard Pt/C and RuO 2 ECs. The superior ORR/OER performances of Sp-Co 3 O 4 /C EC can be ascribed to the synergistic contribution of a high electrochemically active surface area (48.33 m 2 g –1 ), BET surface area (131 m 2 g –1 ), the rich interfacial structure of the crystal facets (111), (220), and (311), and the abundant oxygen vacancies in the sponge-like morphology. Besides the methanol tolerance, accelerated durability and chronoamperometric test established excellent durability and stability in the electrocatalytic operation. This work offers insight into the development of high-performance ORR/OER ECs.