Hierarchical porous carbonaceous materials via ionothermal carbonization of carbohydrates

Abstract

We report on the ionothermal synthesis of porous carbon materials from a variety of carbohydrate precursors (i.e.D-glucose, D-fructose, D-xylose, and starch) using 1-butyl-3-methylimidazolium tetrachloroferrate(III), [Bmim][FeCl₄] as a reusable solvent and catalyst. The carbon materials derived from these different carbohydrates are similar in terms of particle size and chemical composition, possessing relatively high surface areas from 44 to 155 m² g⁻¹ after ionothermal processing, which can be significantly increased to >350 m² g⁻¹ by further thermal treatment (e.g. post-carbonization at 750 °C). CO₂ and N₂ sorption analysis, combined with Hg intrusion porosimetry, reveals a promising hierarchical pore structuring to these carbon materials. The ionic liquid [Bmim][FeCl₄] has a triple role: it acts as both a soft template to generate the characterized pore structuring, solvent and as a catalyst resulting in enhanced ionothermal carbon yields. Importantly from a process point of view, the ionic liquid can be successfully recovered and reused. The current work shows that ionothermal synthesis has the potential to be an effective, low cost, and green reusable synthetic route towards sustainable porous carbon materials.