Preparation of amide-enriched micro-mesoporous carbons from bayberry core via prepolymerization and ammonization co-treatment for high-performance supercapacitors

The rational design and synthesis of environmental, low-cost and eco-friendly renewable biomass-based carbons are highly desired for the development of high-performance supercapacitors. Herein, a novel amide-enriched synthesis strategy for biomass-based carbon from bayberry core (BC) by in-situ melamine-BC prepolymerization and subsequent NH3 ammonization. The synthesized biomass-based BC carbons were characterized by N2 adsorption/desorption, scanning electron microscope, Raman spectroscopy, Fourier transform infrared spectroscopy and X-ray photoelectron spectroscopy. The results showed that the BC carbons by melamine and ammonization co-treatment had both much higher N-doping level (up to 6.43%) and surface area (up to 960 m2 g−1) than the N-free doped carbon. The doped N functional group was mainly dominated by the form of amide-N rather than pyridine-N or quaternary-N. More excitingly, the amide-N content increased with the extension of ammonization time while pyridine-N and quaternary-N went down. The prepared amide-enriched BC carbon via 20 g melamine pre-polymerization and 3 h ammonization treatment delivered an excellent specific capacitance of 259 F g−1, which was 35–72 F g−1 higher than the samples by 1h and 2h NH3 treatment though the latter two had much higher surface area, pyridine and quaternary-N content. The results indicated that the amide-N on the N-doped biomass-based carbon made a great role for enhancing the capacitance, and its promotion to electric double layer capacitance and pseudo-capacitance exceeded that of pyridine and quaternary-N.