Capacitive performance of ordered mesoporous carbons with tunable porous texture in ionic liquid electrolytes

Ordered mesoporous carbons with tunable pore size and surface chemical properties are prepared by doping boric acid using a hard-templating method. The capacitive performance of these carbons is investigated in two common ionic liquids of EMImBF₄ and EMImTSFI. As demonstrated by the structure analysis, the pore size increases from 3.3 to 5.7 nm and the content of oxygenated groups on the carbon surface increases from 2.0 to 5.2 mol% with the increase of the boron doping from 0 to 50 mol%. In ionic liquid electrolyte, the carbons mainly show typical electric double layer capacitance, and the capacitance retention ratio and ion diffusion in the carbon channels is determined to the surface chemical property. The prepared carbons present visible pseudo-capacitance due to the rapid redox reactions of the oxygenated groups in hydrophilic EMImBF₄, reflecting by the increasing of the specific surface capacitance, while no visible pseudo-capacitive behavior was observed in hydrophobic EMImTSFI.