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In recent years, ternary transition metal oxides (TTMOs), especially spinel type TTMOs have attracted widespread attention as promising candidates for electrode materials. Among all of the popular TTMOs, MgCo O is an outstanding one, owing to its superior theoretical capacitance. In this work, MgCo O nanosheet arrays (NSAs) grown directly on nickel foams were fabricated through a facile hydrothermal process at 120 °C for 4 h. With a series of structural and morphological characterization techniques, it was found that the ethanol played a key role in controlling the composition and morphology during the synthesis process. The MgCo O NSAs exhibited a superior specific capacitance of 853.06 C g (at 1 mA cm ) and enhanced cycling performance, with 94.65 % of initial capacitance retained after 3000 cycles when used as a binder-free integrated electrode for electrochemical supercapacitors; much higher than other reported data for MgCo O as well. The excellent electrochemical properties mainly came from the unique morphology of the MgCo O NSAs. This study will demonstrate the applications of MgCo O NSAs based large-scale supercapacitors grown on low-cost nickel foams.

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Vanadium‐based metal oxides have attracted widespread attention as a promising candidate for electrode materials owing to the novel morphologies and the wide range of practical applications. In this work, the microwave‐assisted hydrothermal synthesis method was used for the first time to synthesize CoV2O6 micron blocks and Co3V2O8 nanoparticles. Briefly, heating the solution to 100 °C and adjusting the pH can result in desired micro blocks and nanoparticles within 10 min. After systematic characterization of material structures and morphologies, the resulted two materials were further fabricated to electrodes, and thoroughly characterized their electrochemical performances. The test results showed that both the two cobalt vanadates had a great potential as supercapacitor electrode materials. Moreover, by adjusting the pH of the solution, the type and morphology of the synthesized product could be precisely controlled, which could largely affect the electrochemical properties of the materials.

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