Templated synthesis and activation of highly nitrogen-doped worm-like carbon composites based on melamine-urea-formaldehyde resins for high performance supercapacitors

Nitrogen–rich carbon materials with hierarchical porosity were obtained by pyrolyzing melamine-urea-formaldehyde (MUF) resins between 650 and 850 °C with a mesoporous silica template, followed by KOH activation under N2 atmosphere. In the synthesis process, the high nitrogen-containing MUF resins serve not only as carbon precursor but also as nitrogen source, and nitrogen content can be easily controlled by the carbonization temperature. The resulting MUF resins-derived porous carbon(MUFCx) exhibits a high surface area (up to 2563.4 m2 g−1) with nitrogen content varying from 14.25 to 11.68 at.%, respectively. As expected, electrochemical measurements show that the sample carbonized at 750 °C exhibits improved capacitance properties, such as an enlarged specific capacity (375 F g−1 at 0.5 A g−1), excellent rate capability (272 F g−1 at 10 A g−1), as well as excellent cycling retention (only 5% loss after 2000 cycles). Furthermore, an as-fabricated MUFC-based symmetric supercapacitor device shows a high energy density of 23.43 W h kg−1 at a power density of 450 W kg−1 operated in the voltage range of 0–1.8 V in 1 M Na2SO4 aqueous electrolyte.