Selective etching of C-N bonds for preparation of porous carbon with ultrahigh specific surface area and superior capacitive performance

Abstract

In consideration of the C-N bond is significantly weaker than C-C bond by about 30 kcal/mol, a selective etching of C-N bonds strategy has been put forward to prepare porous carbons with high specific surface area. The strategy has been characterized by a combination of experimental and theoretical techniques. The key to this success includes two-folds: the uniformly distributed C-N bonds and their preferential etching over the vast C-C bonds in the carbon precursors. Consequently, polydopamine with high nitrogen content is chosen as the precursor, through in situ C-N bond etching with KOH, a hierarchical porous carbon with an ultrahigh specific surface area of 3965 m2/g has been prepared, and the total pore volume is as high as 4.02 cm3/g. Specifically, the porous carbon showed a high specific capacitance of 342 F/g at 1 A/g and retained 268 F/g even at 10 A/g in 6 M KOH. Meanwhile, the symmetric supercapacitor devices deliver energy density of 29.2 Wh/kg at 347.5 W/kg and 20.7 Wh/kg at 10.3 kW/kg in 1 M Li2SO4 aqueous electrolyte. Impressively, in organic electrolyte, it retains a high energy density of 80.8 Wh/kg even at 26.9 kW/kg.