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Recently, metal–organic framework (MOF)-derived binary transition-metal oxide (BTMO) holds promise as an ideal electrode material for energy-storage applications. Here, we report a facile synthesis procedure of MOF-derived BTMO that commences with the preparation of Cu-MOF through the coordination of Cu 2+ with 2-MeIM. Subsequently, Ni 2+ is introduced into the Cu-MOF to create Cu 2+ and Ni 2+ binary clusters, resulting in the formation of Ni-Cu-MOF. Finally, annealing of Ni-Cu-MOF led to the formation of a nanoflakes morphology of Ni 2 CuO 3 /CuO (denoted as NCO/CuO) composite that serves as an efficient pathway for both ion and electron transportation, creating plentiful active sites for the faradaic charge storage process. Impressively, the NCO/CuO composite demonstrates significantly higher specific capacity ( C s ) of 613.54 C/g compared to Ni-Cu-MOF (301.11 C/g) at a current density of 1 A/g and retains 66.3% of its initial capacitance at 15 A/g. Similarly, the Fe 2 O 3 -doped nitrogen-doped reduced graphene oxide (denoted as Fe 2 O 3 /N-rGO) composite prepared through a facile hydrothermal method demonstrates a specific capacitance ( C sp ) of 603.39 F/g at 1 A/g, surpassing its counterparts, Fe 2 O 3, and N-rGO and retains 39.6% of its initial capacitance even at a higher current density of 15 A/g. Finally, a flexible asymmetric supercapacitor (ASC) device was designed and assembled using the Ni 2 CuO 3 /CuO composite as the positive electrode, Fe 2 O 3 /N-rGO as the negative electrode, and PVA-KOH gel as the electrolyte. The Ni 2 CuO 3 /CuO//Fe 2 O 3 /N-rGO ASC device demonstrates an excellent energy density of 48.26 Wh/kg at 1 A/g and a maximum power density of 11 250 W/kg and retains 86% of its capacitance after 10 000 cycles at 1 A/g. These findings provide valuable insights for high-performance energy-storage ASC devices for next-generation portable electronics.
Mondal et al. (Thu,) studied this question.