Morphology Effect of Co<sub>3</sub>O<sub>4</sub> Nanooctahedron in Boosting Oxygen Reduction and Oxygen Evolution Reactions
Bhugendra Chutia, Suranjana Patowary, Ashok Misra, Komateedi N. Rao, Pankaj Bharali
Abstract
We report a controllable synthesis of Co3O4 nanooctahedron anchored on Vulcan XC 72R (Oct-Co3O4/C) to explore the crystal symmetry effects on the bifunctional electrocatalysis of oxygen reduction and oxygen evolution reaction (ORR/OER) in alkaline electrolyte. Systematic electrochemical measurements reveal that Oct-Co3O4/C exhibits remarkable ORR/OER activity with a higher ORR onset potential (Eonset = 0.89 V), half-wave potential (E1/2 = 0.68 V), large limiting current density (j = −6.38 mA cm–2), and significantly lower overpotential for 10% energy conversion (η10 = 0.45 V). The superior bifunctional activity can be attributed to the synergistic contribution of high specific surface area (131.3 m2 g–1), electrochemically active surface area (ECSA = 35.83 m2 g–1), and rich oxygen vacancies in the well-defined octahedral crystal symmetry. Furthermore, the chronoamperometric and accelerated durability test demonstrated superior stability and durability for the catalytic process. This study underscores the significance of morphology control in the design of an advanced ORR/OER electrocatalyst in alkaline medium.