MOF−Derived Core-Shell La(OH)3@Cu(OH)2/Co(OH)2 Heterostructure for Supercapacitors

Abstract

Structural metal-organic framework (MOF)-based pseudocapacitive components have exhibited significant potential for supercapacitors. Herein, a highly functioning vertically aligned La(OH)₃@Cu(OH)₂/Co(OH)₂ core-shell composite was in situ yielded from the template Co MOF-74 frameworks on the nickel foam (Co MOF/NF) via a dual approach of heterointerfacing and structural engineering. The sacrificial template Co MOF/NF microrods were converted into binary hydroxide Cu(OH)₂/Co(OH)₂/NF (Cu/Co/NF) junction with spatial nanogranule self-assembled microrods-like structure through a cation exchange reaction. Subsequently, the binary hydroxide Cu/Co junction was employed as a backbone to stabilize La(OH)₃ species via an electrodeposition process, forming a heterostructural La(OH)₃@Cu/Co/NF (La@Cu/Co/NF) core-shell composite. Preliminary electrochemical analysis demonstrates the efficiency of the binder-free La@Cu/Co/NF core-shell electrode, revealing a specific capacitance value of 874.8 F g⁻¹ at 1 A g⁻¹ and high rate ability (65.2 % capacitance retention at 30 A g⁻¹). Hence, it combines rich electrochemical reactive sites for Faradaic redox reactions and the favorable synergistic effect of integrated constituents. The configured La@Cu/Co/NF//AC asymmetric supercapacitor (ASC) device boasts a maximum voltage window of 1.55 V, acquiring an energy density of 43.9 Wh kg⁻¹ at 775 W kg⁻¹. Besides, the device maintains a capacitance retention rate of 76.4 % even after enduring 11,000 charge-discharge cycles, suggesting good long-term durability.