Dual-ligand strategies to assemble S, N-containing metal organic framework nanoflowers for hybrid supercapacitors

Abstract

Metal–organic frameworks (MOFs) are excellent electrode materials due to their unique structure and properties. However, in many reports, MOF materials are used as precursor materials for porous carbon and metal oxides owing to their inadequate stability. Herein, S, N-containing Ni-MOF [Ni(thiophene-2,5-dicarboxylate)(4,4′-bipyridine)]_n nanoflowers have been synthesized using a dual-ligand strategy under low-temperature hydrothermal conditions. The influences of nickel salt (NiSO₄, Ni(NO₃)₂, and NiCl₂) on the morphology, specific surface area, pore size, and electrochemical properties of the obtained Ni-MOFs are investigated. The results show that the Ni-MOFs prepared using NiSO₄ have excellent electrochemical properties and deliver a high specific capacity of 759 Fg⁻¹ at 0.5 A g⁻¹ and exhibit excellent rate performance (62.7% capacity retention at 10 A g⁻¹). When a hybrid supercapacitor is assembled using a Ni-MOF as a cathode and activated carbon as an anode, it shows a high energy density of 30.72 W h kg⁻¹ at a power density of 400 W kg⁻¹. Furthermore, the device exhibits excellent cycling stability (86.26% retention after 5000 cycles). The synthesized Ni-MOF nanoflowers show great potential in high-performance supercapacitors.