Reduced Graphene Oxide Supported CoO/MnO₂ Electrocatalysts from Layered Double Hydroxides for Oxygen Reduction Reaction

Graphical abstract: Display Omitted We fabricated CoO/MnO₂/RGO multicomponent electrocatalyst for oxygen reduction reaction in alkaline medium from Co, Mn-containing layered double hydroxides by calcination at 550 °C under nitrogen atmosphere. This obtained composite has shown excellent electrocatalytic performance related to single component and the mechanical mixture because of synergistic effects between CoO and MnO₂. Furthermore, this electrocatalytic performance is comparable with that of the commercial Pt/C catalyst. -- Highlights: •CoO/MnO₂/RGO multicomponent electrocatalyst was fabricated from LDH. •CoO/MnO₂/RGO has shown excellent electrocatalytic performance for ORR. •Synergistic effects are confirmed between CoO and MnO₂. -- Abstract: It is of great interest to explore non-precious metal electrocatalysts with high catalytic activity, complete tolerance, and long durability for oxygen reduction reaction (ORR) and then to move the alkaline fuel cell technology closer to commercialization. Here, we fabricated reduced graphene oxide (RGO) supported CoO/MnO₂ nanocomposites from Co, Mn-containing layered double hydroxides (Co₃Mn-CO₃-LDH) by calcination at 550 °C under nitrogen atmosphere. Also, we systemically investigated the electrocatalytic performance of CoO/MnO₂/RGO composite for ORR in 0.1 M KOH. Because of synergistic effect between CoO and MnO₂, the CoO/MnO₂/RGO nanocomposite exhibits excellent ORR catalytic activity with a 4-electron transfer pathway, an onset potential of 0.95 V vs. RHE, a half-wave potential of 0.76 V vs. RHE, and cathodic current density of 4.2 mA cm⁻² at 0.5 V vs. RHE at a rotating speed of 1600 rpm, which are comparable with the commercial Pt/C catalyst. Furthermore, the catalyst has complete tolerance to methanol and longer durability compared to the Pt/C catalyst under the investigated conditions. The CoO/MnO₂/RGO nanocomposite is one of promising non-precious metal electrocatalysts for alkaline membrane/membraneless fuel cells