Rapid Synthesis and Efficient Electrocatalytic Oxygen Reduction/Evolution Reaction of CoMn₂O₄ Nanodots Supported on Graphene

Abstract

Transition-metal oxides have attracted extensive interest as oxygen-reduction/evolution reaction (ORR/OER) catalyst alternatives to precious Pt-based materials but generally exhibit limited electrocatalytic performance due to their large overpotential and low specific activity. We here report a rapid synthesis of spinel-type CoMn2O4 nanodots (NDs, below 3 nm) monodispersed on graphene for highly efficient electrocatalytic ORR/OER in 0.1 M KOH solution. The preparation of the composite involves the reaction of manganese and cobalt salts in mixed surfactant-solvent-water solution at mild temperature (120 °C) and air. CoMn2O4 NDs homogeneously distributed on carbonaceous substrates show strong coupling and facile charge transfer. Remarkably, graphene-supported CoMn2O4 NDs showed 20 mV higher ORR half-wave potential, twice the kinetic current, and better catalytic durability compared to the benchmark carbon-supported Pt nanoparticles (Pt/C). Moreover, CoMn2O4/reduced graphene oxide afforded electrocatalytic OER with a current density of 10 mA cm(-2) at a low potential of 1.54 V and a small Tafel slope of ∼56 mV/dec. This indicates that the composite of CoMn2O4 nanodots monodispersed on graphene is promising as highly efficient bifunctional electrocatalysts of ORR and OER that can be used in the areas of fuel cells and rechargeable metal-air batteries.

Electrocatalytic and pseudocapacitive properties of cobalt (hydro)oxide films on sintered metal fiber filter

“…A smaller Tafel slope suggests that the ratedetermining step is at the ending part of the multiple electron transfer reaction [39]. The obtained results show that Co 3 O 4 films on sintered metal fiber can be assessed as highly effective and stable electrode for OER, the activity being very similar to those obtained by other authors using nanocomposites [40,41] or metal-doped structures [2,12,[42][43][44][45][46].…”

Oxygen reduction electrocatalysts based on spatially confined cobalt monoxide nanocrystals on holey N-doped carbon nanowires: the enlarged interfacial area for performance improvement

“…7 The Co(II)/Co(III) redox couple is proposed to be concurrent with the ORR. 22 While evaluating the ORR activity of catalysts by CV characterization, the well-dened cathodic peaks for O 2 -reduction are visible in the O 2 -saturated electrolyte, whereas featureless voltammetric currents were observed under N 2 (Fig. 22 While evaluating the ORR activity of catalysts by CV characterization, the well-dened cathodic peaks for O 2 -reduction are visible in the O 2 -saturated electrolyte, whereas featureless voltammetric currents were observed under N 2 (Fig.…”

Preparation of Ag4Bi2O5/MnO2 Corn/Cob Like Nano Material as a Superior Catalyst for Oxygen Reduction Reaction in Alkaline Solution

“…Additionally, the platinum (Pt) or platinum-based materials are sensitive to poisoning by methanol [5]. Recently, intensive research has been conducted to develop platinum free catalysts, such as silver (Ag) [6][7][8][9], manganese oxide [10][11][12][13], and silver/manganese oxide composite [14][15][16], which are promising catalysts with excellent performance at room temperature for alkaline fuel cells. Manganese oxides are promising catalysts for the oxygen reduction reaction owing to their outstanding activity toward oxygen reduction with the advantages of low cost and abundance [17].…”