Synthesis of N-doped Carbon Materials with Controlled Pore Sizes from Double-Network Hydrogels

Abstract

A series of nitrogen-doped carbon materials with different specific surface areas (SSA) and controlled pore size distributions (PSD) were synthesized through a facile and low-cost method. Double network hydrogels (DN gel) were synthesized from Agarose as the 1st network and polyacrylamide as the 2nd network and used as the precursor. To afford the micro porous structure, potassium oxalate (K2C2O4) was used as activating agent. The nitrogen doped carbon foam obtained from the DN gel has a higher surface area than a single network. The highest surface area (~2447.4 m2/g) was obtained at 700 °C when the precursor to activating agent ratio was 1:1 (g:g). The pore size distribution can be controlled by changing the time or temperature. The transformation of micro pores to mesopores was investigated by increasing the heat treatment temperature from 600 °C to 800 °C. As a metal-free electrocatalyst, it was examined for oxygen reduction reaction (ORR) in alkaline media. As a result, N-doped carbon materials from the double network showed higher electrocatalytic performance than single networks.