Ternary MnO2/NiCo2O4/NF with hierarchical structure and synergistic interaction as efficient electrocatalysts for oxygen evolution reaction
By Yan, Kai-Li; Shang, Xiao; Gao, Wen-Kun; Dong, Bin; Li, Xiao; Chi, Jing-Qi; Liu, Yan-Ru; Chai, Yong-Ming; Liu, Chen-Guang
Published in Journal of Alloys and Compounds
2017
Abstract
Abstract Ternary metal oxides MnO2/NiCo2O4 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 MnO2/NiCo2O4/NF also possess the advantage of synergistic effect between MnO2 and NiCo2O4, implying the enhanced intrinsic activity for OER. XRD, {EDX} and {XPS} confirm the existence and distribution of each element of MnO2/NiCo2O4/NF. {SEM} shows the hierarchical structure of MnO2/NiCo2O4/NF with vertically aligned MnO2/NiCo2O4 nanoflakes covering on the surface of NF, which is in favor of the more exposed active sites and the fast dissipation of {O2} bubbles. Additionally, to clearly testify the significance of the vertically aligned MnO2/NiCo2O4 nanoflakes, non-vertical MnO2/NiCo2O4/NF sample (MnO2/NiCo2O4/NF-1) is prepared for comparing {OER} performances in the same condition. {OER} measurements in alkaline solution show that ternary MnO2/NiCo2O4/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.