Electrochemical performance of MOF-5 derived carbon nanocomposites with 1D, 2D and 3D carbon structures

Abstract

Three kinds of carbon nanomaterials representing one-dimensional (carbon nanotubes (MWCNT)), two-dimensional (graphene oxide (GO)) and three-dimensional (hollow nanospheres (CS)) structures have been selected as additives for the formation of metal-organic frameworks derived carbon nanocomposites. For comparative study, the nanomaterials components were introduced to carbon matrix in two routes: (1) physical mixing, (2) chemical mixing - in situ during MOF-5 synthesis. The procedures resulted in the formation of the nanocomposites based on the carbonized metal-organic framework with various carbon nanostructures. The study verified the difference in the electrochemical performance, as an electrode component in supercapacitors, related to different dimensionality of the carbon additives and their impact on the nanocomposites morphology, structure and surface area. In general, it turned out that composites obtained by physical mixing exhibit much better cycling stability than those obtained via chemical route. All the nanocomposites retained more than 88% of the initial capacitance after 3500 cycles at current density of 10 A/g and the best performance was observed in the composite with graphene oxide (93%). However, the composites obtained in situ exhibited higher specific capacitance. The best electrochemical properties were observed in supercapacitors based on graphene oxide (CMOF-5-GO) which acted as a template for MOF-5 formation. CMOF-5-GO has specific surface area of 1702 m2/g and high total pore volume of 2.76 cm3/g what influenced its excellent electrochemical properties (specific capacitance - 195.4 F/g at current density of 1 A/g).