A generalized ZnCl2 activation method to produce nitrogen-containing nanoporous carbon materials for supercapacitor applications

We demonstrate a generalized but efficient ZnCl2 activation method to produce nitrogen-containing nanoporous carbon materials, using 4-(4-nitrophenylazo)resorcinol, sodium 5-[(4-nitrophenyl)azo]salicylate, and tartrazine as carbon/nitrogen sources. It reveals that the mass ratios between carbon/nitrogen precursors and ZnCl2 activating agent, and activation temperatures have crucial impacts upon carbon structures as well as the resultant capacitive behaviors. The carbon samples produced in this work are amorphous in nature. The carbon sample obtained by the ZnCl2 activation of 4-(4-nitrophenylazo)resorcinol at 900 °C, named as carbon-1#, exhibits the largest nitrogen contents of 5.96% and best porosity, including the BET surface area of 891.1 m2 g−1, and total pore volume of 0.54 cm3 g−1. As a result, the carbon-1# sample delivers the superior specific capacitances of 431.5 F g−1 at a current density of 1 A g−1, as well as long-term cycling stability of 97.16% even after charging-discharging for 10,000 times. The present ZnCl2 activation method is expected to produce other carbon materials, exhibiting large porosities and superior electrochemical behaviors for supercapacitor applications.