Hierarchical porous carbon microspheres from resorcinol-formaldehyde for supercapacitor and methylene blue adsorption

Hierarchical porous carbon microspheres were prepared through solvothermal route with resorcinol and formaldehyde as precursors in HCl solution followed by pyrolysis at high temperature. The micropore size, graphitic carbon and surface C = O bond increase while mesopore size decreases as elevation of pyrolysis temperature. The presence of high specific surface area, micropore volume and amorphous carbon is beneficial to improve supercapacitor performance. The carbon material obtained at 1000 oC (C1000) has high specific surface area of 667.79 m2g- 1 and micropore volume of 0.35 m3g- 1, which shows the specific capacitance of 122 Fg- 1 at the current density of 1 Ag- 1 in 6 M KOH solution and good capacitance retention of 100% after 5000 cycles at 5Ag- 1. The specific surface area and micropore volume reduce as increase of pyrolysis temperature. Besides the high specific surface area, mesopore volume and surface C = O bond, the micropore size distribution contributes significantly to the adsorption of methylene blue (MB). The carbon material synthesized at 1200 oC (C1200) exhibits the adsorption equilibrium capacity of 99.3 mgg- 1 and capacity retention of 83.5% after five cycles.