Oriented Catalytic Oxidation Induced Fabrication of CuO/Mn 3 O 4 Hierarchical Arrays as Binder‐Free Electrodes for High‐Performance Supercapacitor

Abstract Herein, the authors report the fabrication of copper oxide/manganese oxide (CuO/Mn 3 O 4 ) hierarchical arrays on Cu substrate via an oriented catalytic oxidation combined with subsequent annealing. Based on an ingenious oriented catalytic oxidation process, abundant CuO/Mn 3 O 4 nanosheets are directionally modified on the surface of Cu(OH) 2 nanorod arrays which are uniformly grown on the Cu substrate. Through subsequent annealing treatment in an N 2 atmosphere, CuO/Mn 3 O 4 nanorod arrays are fabricated with tuned oxygen vacancies. The 3D hybrid nanoarray structure with advantages of enhanced electron transfer, a large exposed surface area, and robust structure stability can address the drawbacks associated with bare CuO electrodes. As a result, the as‐prepared CuO/Mn 3 O 4 nanoarray electrode demonstrates excellent electrochemical performance, delivering a high specific capacitance of 433 mF cm −2 at 5 mA cm −2 (1732 F g −1 at 20 A g −1 ), and achieving a long cycling lifespan with 144% capacitance retention at 20 mA cm −2 after 20 000 cycles. Interestingly, this facile oriented catalytic oxidation strategy can be extended to prepare other metal oxides/hydroxides (Ni 2+ , Co 2+ , Cu 2+ , Zn 2+ , or mixed ions based) on the surface of Cu(OH) 2 nanorod templates respectively, manifesting its versatility for preparing CuO‐based hybrid nanorod arrays on the Cu substrate.