Engineering Co3O4/MnO2 nanocomposite materials for oxygen reduction electrocatalysis

Stable and active electrocatalysts preparation for the oxygen reduction reaction (ORR) is essential for an energy storage and conversion materials (e.g. metal-air batteries). Herein, we prepared a highly-active MnO2 and Co3O4/MnO2 nanocomposite electrocatalysts using a facial co-precipitation approach. The electrocatalytic activity was examined in alkaline media with LSV and CV. Additionally, the physicochemical characteristics of the MnO2 and Co3O4/MnO2 composite materials were studied via SEM, XRD, BET, UV-Vis, TGA/DTA, ICP-OES and FTIR. Morphological studies indicated that a pure MnO2 has a spherical flower-like architecture, whereas Co3O4/MnO2 nanocomposites have an aggregated needle-like structure. Moreover, from the XRD investigation parameters such as the dislocation density, micro-strain, and crystallite size were analyzed. The calculated energy bandgaps for the MnO2, Co3O4/MnO2-1-5, and Co3O4/MnO2-1-1 nanocomposites were 3.07, 2.6, and 2.3 eV, correspondingly. The FTIR spectroscopy was also employed to study the presence of M-O bonds (M = Mn, Co). The thermal gravimetric investigation showed that the Co3O4/MnO2 nanocomposite materials exhibited improved thermal stability, confirming an enhanced catalytic activity of ORR for MnO2/Co3O4-1-1 composite materials for ORR. These results confirm that the prepared Co3O4/MnO2 composite materials are promising air electrode candidates for the energy storage and conversion technologies.