Capacitance performance boost of cellulose-derived carbon nanofibers via carbon and silver nanoparticles

Carbon nanofibers (CNFs) have attracted much attention as effective materials for energy storage devices. Here, silver nanoparticles (AgNPs) were in situ synthesized on the cellulose nanofibers containing vapor grown carbon nanofibers (VGCNFs) for producing carbon nanofibers with desirable properties toward electrochemical applications. Carbon nanofibers were fabricated by electrospinning of cellulose acetate solution containing 0.5 wt% VGCNFs followed by deacetylation and carbonization. Dopamine as a carbon source with high amine content was introduced as poly-functional compound that served as a reducing, adhesive, binding and stabilizing agent for production of silver nanoparticles as well as forming a carbon layer with high nitrogen content on CNF surfaces after heat-treatment. The carbon nanofibers were characterized by scanning electron microscopy (SEM), X-ray diffraction, X-ray photoelectron spectroscopy, energy-dispersive X-ray (EDX), Raman spectroscopy and thermogravimetric examinations (TGA). TGA results demonstrated that dopamine increases thermal stability of cellulose nanofibers, causing higher carbon yield for the final product. Also, EDX pattern and SEM images confirmed the presence of Ag nanoparticles with the uniform distribution and average size of 30 nm. The low cost filler (VGCNFs) and AgNPs were used to improve the electrical properties while dopamine enhanced the pseudocapacitance effects. The final carbon nanofibers containing VGCNFs, Ag and nitrogen exhibited electrical conductivity of 6.41 S cm⁻¹ and specific capacitance of 216 F g⁻¹, about 4 times higher than pure CNFs. The CNFs derived from electrospun cellulose containing conductive metal (Ag), non-metal (VGCNFs) nanoparticles and also nitrogen can be applied as an electrode for high-performance supercapacitors.