Nitrogen Doped Hydrothermal Carbon for Supercapacitors
Currently, a number of technologies have been utilized to dope nitrogen into carbon structures, such as electric arc, pyrolysis, hydrothermal and pre/post treatments with nitrogen sources. Of these, hydrothermal carbonization (HTC) is one of the most promising techniques in carbon materials research. In comparison to other carbonization techniques, HTC offers an environmentally friendly approach to the formation of highly functionalized, doped carbon structures from renewable sources as carbonization occurs under water at substantially lower temperatures (180°-300°C). Furthermore, heteroatoms incorporation, chemical and structural morphology as well as surface functionality can be easily controlled through the manipulation of the treatment conditions, solution pH and addition of soluble additives (i.e., (NH4)2SO4.
In this study, we have investigated the chemical structure via NEXAFS, morphology and electrochemical performance of hydrothermal carbons produced from sucrose doped with different ammonium salts. This produced nitrogen doped carbons with a spherical morphology with a wide variety of oxygen and nitrogen functionalities spread across the surface. Electrochemically, these carbons displayed a wide range of psudocapacitive behaviour as well as electrical double layer capacitance, delivering up to 200 F/g in three electrode cells with 1 M KOH as the electrolyte.