Sustainable Upcycling of Nitrogen-Enriched Polybenzoxazine Thermosets into Nitrogen-Doped Carbon Materials for Contriving High-Performance Supercapacitors

Abstract

Nitrogen-enriched polybenzoxazine thermosets derived from the ring-opening polymerization of side-chain-type benzoxazine-functionalized polyethylenimine resins (Bz-pei) have been previously reported by our group. In view of the appreciable nitrogen content and significant char yield, these thermosets have been envisioned as enticing carbon precursors and therefore have been sustainably upcycled to nitrogen-doped carbon materials. It is worth mentioning that the sustainable upcycling method should circumscribe energy as well as cost consumption, due to which carbon materials in the present work have been developed under moderate carbonization conditions, without chemical activation treatment. The developed nitrogen-doped carbon materials have been characterized by using Fourier transform infrared (FTIR) spectroscopy, X-ray diffraction (XRD), Raman spectroscopy, elemental analysis, X-ray photoelectron spectroscopy (XPS), and thermogravimetric analysis (TGA). The pore topography has been analyzed using scanning electron microscopy (SEM), and energy-dispersive X-ray (EDX) analysis has been performed, while the Brunauer–Emmett–Teller (BET) surface area has been determined using nitrogen adsorption–desorption experiments. A comparison of the results obtained from electrochemical investigations performed in a three-electrode setup shows that carbon material upcycled from the guaiacol-based polybenzoxazine thermoset, exhibiting 6.4% nitrogen doping in the carbon framework (labeled as C-GP81), exhibits an impressive capacitance of 700 F g–1 at 10 A g–1 current density, suggesting excellent efficiency and rate capability of the obtained N-doped carbon-material-based supercapacitor electrodes. Furthermore, the carbon material designated as C-GP81 could deliver a maximum energy density (Ed) of 48 Wh kg–1 at a power density (Pd) of 8400 W kg–1 in a three-electrode configuration. The performance of the crafted supercapacitor device for the present study has surpassed the performance reported for polybenzoxazine-derived carbons. Additionally, the performance of carbon material labeled as C-GP81 has been evaluated for its potential as an active component in the electrodes of a symmetric device.