Novel cobalt-incorporated two dimensional covalent organic frameworks for supercapacitor applications

Abstract

Covalent-organic frameworks (COFs), are a promising new class of crystalline porous organic materials with confined structures either in 2D or 3D domains. The current study focuses on using a solvothermal approach consisting of sealed pyrex tubes to synthesize two-dimensional TBP-COF and TBP-COF that have been doped with cobalt (Co) (TBP-Co@COF). The results of the experimentally acquired X-ray diffraction study were compared with those from simulations, and it was discovered that both are in good agreement. A thorough theoretical analysis of the layer packing in AA stacking (P1) and AB stacking (P1) modes using the Materials Studio revealed that AA stacking is more stable than the AB stacking (P1) structure. The formation of imine linkage and incorporation of Co into the COF are indicated by the result of XPS. Unaggregated dispersion of Co particles can be seen on the square and rectangular sheets of TBP-COF in TEM and SEM images. Both materials are fabricated as electrode materials and evaluated for their supercapacitor applications. The TBP-Co@COF shows an enhanced specific capacitance (CSp) of 975F/g compared to the TBP-COF (827F/g) at 2 mV/s scan rate. TBP-Co@COF exhibit an energy density (ED) of 69 Wh/kg even at a high power density (PD) of 75000 W/kg and also retains 79 % of its initial capacitance up to 2000 cycles. TBP-COF and TBP-Co@COF were fabricated for an asymmetric supercapacitor device (ASD) and found to exhibit a CSp of 191F/g at a scan rate of 2 mV/s.