Exploring acetate precursor based nickel-cobalt metal-organic frameworks and graphene oxide nano-composites for supercapacitors

Abstract

Herein, the unprecedented influence of metal precursors on the morphology and electrochemical performance of MOF materials is explored. Three different metal salts, namely acetate, chloride and nitrate of nickel and cobalt are utilized to synthesize MOFs. Subsequently, the composite of graphene oxide (GO) with Acetate-MOF revealed enhanced charge transfer kinetics and electrochemical properties of Acetate-MOF-4 which are contributing to advanced supercapacitors. At current density of 10 mA cm-2, Acetate-MOF exhibited higher specific capacitance (763.8 F g-1) than Chloride-MOF and Nitrate-MOF. Interestingly, with the addition of GO at an optimized concentration, Acetate-MOF-4 showed a high specific capacitance of 991.2 F g-1 and a high cyclic stability of 72.22 % after 2000 cycles, which is superior compared to Acetate-MOF (63.01 % after 1500 cycles). Further, an asymmetric Acetate-MOF-4//AC supercapacitor is assembled which shows a specific capacitance of 75.6 F g-1 at 10 mA cm-2, a power density of 1562.5 W kg-1 and enhanced cyclic stability 144.83 % of the initial capacitance after 2000 cycles. Consequently, the present study offers a systematic way to study electrochemical properties using important information about optimizing metal precursors and composites.