Ternary MnO2/NiCo2O4/NF with hierarchical structure and synergistic interaction as efficient electrocatalysts for oxygen evolution reaction

Abstract Ternary metal oxides MnO 2 /NiCo 2 O 4 supported on nickel foam (NF) as electrocatalysts for oxygen evolution reaction (OER) have been fabricated via a two-step hydrothermal process. NF as support can provide excellent conductivity and 3 dimensional skeleton, which facilitate the utilization of active sites and mass transfer of electrolyte. The ternary MnO 2 /NiCo 2 O 4 /NF also possess the advantage of synergistic effect between MnO 2 and NiCo 2 O 4 , implying the enhanced intrinsic activity for OER. XRD, EDX and XPS confirm the existence and distribution of each element of MnO 2 /NiCo 2 O 4 /NF. SEM shows the hierarchical structure of MnO 2 /NiCo 2 O 4 /NF with vertically aligned MnO 2 /NiCo 2 O 4 nanoflakes covering on the surface of NF, which is in favor of the more exposed active sites and the fast dissipation of O 2 bubbles. Additionally, to clearly testify the significance of the vertically aligned MnO 2 /NiCo 2 O 4 nanoflakes, non-vertical MnO 2 /NiCo 2 O 4 /NF sample (MnO 2 /NiCo 2 O 4 /NF-1) is prepared for comparing OER performances in the same condition. OER measurements in alkaline solution show that ternary MnO 2 /NiCo 2 O 4 /NF displays better electrocatalytic activity with a low overpotential of 340 mV at a current density of 10 mA cm −2 than other samples. Therefore, ternary metal oxides with hierarchical structure on NF may be a promising choice for excellent electrocatalysts for OER.