Preparation of hierarchically porous carbon nanosheets by carbonizing resol resin for supercapacitors

Hierarchically porous carbon nanosheets were synthesized by using homogeneous mixture of soluble phenolic resin and KOH activator, which was carbonized and activated through one step. Structural characterization revealed that the as-prepared carbon materials consisted of abundant macropores, mesopores and micropores from the carbonization of the resin and activation of KOH. With the appropriate ratio of KOH to resol resin, hierarchically porous carbon nanosheets with specific surface area beyond 3000 m2g−1 and average pore size of up to 3.44 nm were achieved, which exhibited a high specific capacitance of 365.6 F g−1 at 0.5 A g−1, excellent cycle life with 98.7% specific capacitance retained after 10,000 cycles, and high energy density of 12.7 Wh Kg−1 when measured as an electrode in a coin type symmetric supercapacitor in 6 M KOH electrolyte, indicating a promising electrode material for real energy storage in supercapacitors.