Ultrafast post-synthetic modification of a pillared cobalt(ii)-based metal–organic framework via sulfurization of its pores for high-performance supercapacitors

Abstract

In this study, a fast and simple technique (2 min) has been developed to modify the pores of a novel micro-porous, amide-functionalized Co(II)-based MOF [Co(oba)₂(bpfb)₄](DMF)₂, TMU-61, (H₂oba = 4,4′-oxybis(benzoic acid) and bpfb = N,N′-bis-(4-pyridylformamide)-1,4-benzenediamine). The material produced through sulfurization of TMU-61, at ambient temperatures, can be used as an appropriate electrode material for supercapacitors (SCs). The highest specific capacitance of a system with three electrodes is 636.6 F g⁻¹ at a current density of 5 A g⁻¹, and the specific capacitance retention is nearly 94% after 6000 cycles, demonstrating an impressive long-term cycling stability. The asymmetric SC (ASC) based on S-TMU-61 showed the highest energy density (25.73 W h kg⁻¹) and power density (2549.3 W kg⁻¹). Additionally, it is observed that two S-TMU-61 ASCs connected in series are enough to supply energy for lighting blue, yellow, green and red light emitting diodes (LED) for 22 min and driving a mini rotating motor, demonstrating the excellent potential of the new material for a variety of applications. To the best of the authors’ knowledge, this is the first study to use post synthetic modification of a MOF with a suitable pore size to optimize the material for use in SCs.