Facile Ionothermal Synthesis Of Microporous And Mesoporous Carbons Fromtask Specific Ionic Liquids

摘要

Carbonaceous materials are ubiquitous in various technological and energy-related applications, including separations, catalysis, and energy storage/conversion because of their unique physicochemical properties. Traditional synthesis methods involve the carbonization of low-vapor pressure polymeric precursors derived from either synthetic (e.g., polyacrylonitrile (PAN), phenolic resins) or natural sources such as pitch and shell nuts. These polymeric species possess low vapor pressures so that cross-linking reactions can proceed with concomitant char formation and without vaporization of the corresponding precursor units. Nonpolymeric carbon sources are rarely used to form carbon because of their uncontrolled vaporization during high-temperature pyrolysis. One key drawback associated with the use of polymeric precursors, however, lies in the difficulty of generating carbon nanocomposites as well as in the formation of quality carbon coatings. Although nonpolymeric molecular species can be used to generate carbonaceous materials under high pressures, in addition to the experimental complexity and safety concerns, carbon yields are typically very low. In this communication, we describe a novel strategy for synthesizing porous carbons via simple one-step thermolysis of suitable task-specific ionic liquid (TSIL) precursors. Keys to the success of our approach lie in the negligible volatility and molecular tunability associated with these highly promising TSIL carbon precursors.rnIonic liquids (ILs) are denned as semiorganic salts that exist in the liquid state below 100 ℃. Initially developed as molten electrolytes for battery applications, already ILs have impacted many disciplines beyond their initial conception, including electrochemistry, separations, chemical synthesis, and advanced materials. The basic structural attribute of ILs is their ionicity, which gives rise to strong Coulombic interactions between the constituent ions in these unique solvents, a feature responsible for the essentially null vapor pressure associated with the vast majority of known ILs. This intrinsic nonvolatility suggests favorable conditions for an intriguing carbonization process based on well-behaved cross-linking reactions of monomeric TSIL precursor units with minimal loss of reactant.