Green Synthesis of Electrospun Porous Carbon Nanofibers from Sucrose and Doping of Ag Nanoparticle with Improved Electrical and Electrochemical Properties

Porous carbon nanofibers (CNF) with high surface area were synthesized by electrospinning a mixture of polymerized sucrose and poly(vinyl alcohol) (PVA) in water. This green method provides an excellent environment friendly alternative to the toxic polymers and solvents commonly used for synthesis of CNF/metal nanoparticle composites. Stabilization at 350 °C and subsequent carbonization of the electrospun polymer at 950 °C in reducing environment formed semi-graphitic CNF. In situ doping of Ag nanoparticles in CNF resulted in a ten-fold increase in electrical conductivity of CNF for as low as 0.1 wt% Ag doping. When tested as electrode in aqueous electrochemical supercapacitor, the positive effect of Ag-doping is revealed by two-fold improvement in capacitance over the pristine CNF at a high current density of 5.0 A g^-1. Interestingly, a continuous increase in capacitance by ∼65% was observed during 5000 continuous cycling which is attributed to increase in active charge storage sites due to gradual opening up of the pores and increasing diffusion of electrolyte ions triggered by enhanced wettability of the electrodes.