Ionic Liquid Based Approaches to Carbon Materials Synthesis

Ionic liquids (ILs) have attracted continuous interest because of their remarkable physicochemical properties, including high thermal and chemical stability, nonflammability, negligible vapor pressure, designable cation/anion pairs, electrical and ionic conductivity, low melting points, and affinity towards many compounds. These properties make ionic liquids valuable in the creation of new materials and new processes throughout almost the entire field of materials chemistry. An emerging field is the use of ionic liquids in carbon-based nanomaterials. Initially, ionic liquids were used as self-templating carbon sources for the generation of unusual carbon materials in which homogeneous heteroatom doping (e.g., N, B, S) can be accomplished fairly easily. Later, ionic liquids were recognized as suitable for use in the conversion of biomass into porous carbon materials, acting as both reaction media and porosity-directing regulator. Such applications open the door towards the synthesis and accurate tuning of carbon nanostructures, for example, pore structure, morphology, heteroatom doping, and surface functionality. In addition, the hybridization of ionic liquids and nanocarbons enables the development of composites by combining the properties of the ionic liquid (e.g., ionic conductivity or catalytic activity) and those of a host (e.g., chemical or mechanical stability). Currently, although the research of this topic is rapidly expanding, the rational design and synthesis of carbon-based materials, particularly their applications in energy storage and transformation, is still in its infancy. In this review, we focus on several aspects of ionic liquid derived carbons with the aim of shedding light on this new topic: 1) Ionic liquids as an advanced medium for carbon synthesis, 2) ionogels derived from nanocarbon, 3) ionic liquids as fluid precursors for functional carbons, and 4) ionic liquid derived carbons for heterogeneous catalysis