ИСТИНА

Carbon based materials are widely applied in electrochemical devices because of high specific surface area, long cycle life and tunable pore structure [1]. Since nanostructured carbon materials are of the great interest for energy storage applications and catalysis, the study of the liquid substrate adsorption on them is important. Apparently, that these results will differ dramatically from liquid nitrogen sorption data. Not only physical adsorption but also specific surface interactions between electrode material and electrolyte will also have influence on electrochemical properties [2]. Surface characteristics of powdered carbon nanomaterials: carbon nanotubes (CNT), carbon nanoshells (CNS), N-doped CNT and CNS, and graphite as a reference non-porous material along with CNT and CNS pellets compacted by spark plasma sintering technique were examined. Adsorption of widely used organic solvents and additives such as ethanol, acetonitrile, benzene; water as one of the most unfavorable impurities (in non-aqueous electrolytes); heptane revealing only physical adsorbtion on carbon materials [3], and 1-methylimidazole as ionic liquid precursor were studied by DVS Advantage instrument (SMS, UK). It was found, that compared to liquid nitrogen adsorption data, the organic vapours sorption reveal smaller values of specific surface areas because of geometry and specific chemical interactions reasons with the exception of ethanol, that presumably condences on the surface because of strong adsorbate-adsorbate interaction. Shapes of adsorption-desorption isotherms of heptane as a chemically inert adsorbate show the presence of micro- and mesopores in all of the materials under discussion. Total pores volume, calculated from liquid nitrogen sorption, is reduced in sintered samples especially carbon nanoshells, but the efficiency of pore loading increases. Experimental heats of sorption of studied pellets do not differ dramatically from original powders, although compared to non-doped carbon nanomaterials pellets, experimental heats of sorption of acetonitrile and 1-methylimidazole on N-doped materials are higher that can be attributed to the chemical interaction of the surface N atoms with polar adsorbate. The heterosubstitution within graphene layers can be the effective way for variation of sorption properties of the surface of carbon nanomaterials due to change of porosity and Coulomb cross-coupling of nitrogen atoms in adsorbent and adsorbate. Experimental heats of sorption of acetonitrile, water, heptane and relative surface areas respective to CNT, CNS, N-CNT, N-CNS, along with pellets compacted by spark plasma sintering were calculated.