Template-based synthesis of Co3O4 and Co3O4/SnO2 bifunctional catalysts with enhanced electrocatalytic properties for reversible oxygen evolution and reduction reaction

• Published in: International journal of hydrogen energy Vol. 48; no. 71; pp. 27568 - 27581
• Main Authors: Milikić, Jadranka, Knežević, Sara, Ognjanović, Miloš, Stanković, Dalibor, Rakočević, Lazar, Šljukić, Biljana
• Format: Journal Article
• Language: English
• Published: Elsevier Ltd 19.08.2023
• Subjects: Bifunctional electrocatalysts; Cobalt (III) oxide; Oxygen evolution reaction; Oxygen reduction reaction; Tin oxide; Oxygen evolution reaction; Cobalt (III) oxide; Tin oxide; Oxygen reduction reaction; Bifunctional electrocatalysts
• ISSN: 0360-3199; 1879-3487
• DOI: 10.1016/j.ijhydene.2023.03.433

Porous cobalt (III) oxide (Co3O4) and mixed cobalt (III) oxide - tin oxide (Co3O4/SnO2) were prepared by a novel template-based hydrothermal method resulting in their spherical morphology as confirmed by thorough physico-chemical characterisation. Two oxides were systematically examined as bifunctional electrocatalysts for oxygen reduction (ORR) and evolution (OER) reaction in alkaline media by voltammetry with rotating disk electrode, electrochemical impedance spectroscopy, and chronoamperometry. Low-cost Co3O4 and Co3O4/SnO2 electrocatalysts showed excellent ORR performance with low onset and half-wave potential, low Tafel slope, and the number of exchange electrons near 4, comparable to the commercial Pt/C electrocatalyst. Low OER onset potential of 1.52 and 1.57 V was observed for Co3O4 and Co3O4/SnO2, respectively, with low charge transfer resistance under anodic polarization conditions. Finally, to test bifunctional activity and durability of the two electrocatalyst, switch OER/ORR test was carried out. [Display omitted] •Spherical Co3O4 and Co3O4/SnO2 were synthesized by the hydrothermal method.•Both electrocatalysts showed excellent ORR performance comparable with Pt/C.•OER at Co3O4 electrocatalyst starts ca. 50 mV earlier than at Co3O4/SnO2.•Co3O4/SnO2 gave comparable OER current densities to Co3O4.•Co3O4 and Co3O4/SnO2 could be promising candidates for metal-air batteries.