Formation of hierarchical CoMoO4@MnO2 core–shell nanosheet arrays on nickel foam with markedly enhanced pseudocapacitive properties

Abstract In this work, the hierarchical CoMoO 4 @MnO 2 core–shell nanosheet arrays have been synthesized, which are grown directly on Ni foam as an integrated electrode for supercapacitors. Nanosheet arrays of cobalt-molybdenum precursors are synthesized first by a mild hydrothermal reaction and used as the “core”. After the second facile hydrothermal process with a successive annealing, the Co–Mo precursors are transformed into the 3D hierarchical CoMoO 4 @MnO 2 core–shell nanostructure. This core–shell heterostructure exhibits desirable electrochemical properties. It shows a high specific capacitance of 2159.4 F g −1 (2.27 F cm −2 ) at 3 mA cm −2 and high cycle stability with 93% retention of its initial specific capacitance at 20 mA cm −2 after 3000 cycles in 1 M KOH solution. In conclusion, the CoMoO 4 @MnO 2 composites could be used as promising electrode materials for electrochemical energy storage due to their remarkable electrochemical properties.