Carbohydrate assisted preparation of N-doped hierarchically porous carbons from melamine resin via high internal phase emulsion template

Facile preparation of N-doped hierarchically porous carbons (NHPCs) is an important research direction in highperformance supercapacitors (SCs). In this paper, we report a high internal phase emulsion (HIPE) template method to prepare NHPCs from melamine resins with the aid of sucrose or glucose, referred as S-NHPCs or GNHPCs, respectively. Sucrose or glucose, formaldehyde, and melamine are dissolved in water as the continuous phase of the HIPE. Under acid catalysis, the continuous phase is cross-linked through aldimine condensation to produce porous melamine resins. Meanwhile, carbohydrate is incorporated via the interaction between the rich oxygen-containing functional groups (-OH, -C--OH) of carbohydrate and the -NH2 groups of melamine through hydrogen bonding and acetal reaction. After carbonization and activation, S-NHPCs or G-NHPCs with high specific surface areas (SSA) are obtained respectively. Besides regulating the porous morphology, biomass carbohydrate can enhance the electrochemical properties of NHPCs via increasing the SSA and hydrophilicity of NHPCs. The SSA of S-NHPC and G-NHPC increased notably from 823 to 1682 m2 g-1 and 1913 m2 g-1, respectively. Meanwhile, owing to the comprehensive N-doping and the developed porous structure, the prepared NHPC based electrodes exhibit excellent specific capacitances (up to 305 F g-1 at 1 A g-1), satisfactory cycling stability, and remarkable rate performance in a three-electrode system.