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

Abstract

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 (ΔE = E j10 − 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 highperformance ORR/OER ECs.