Synthesis of porous carbon nanotubes foam composites with a high accessible surface area and tunable porosity

Abstract

The macroscopic shaping of carbon nanostructure materials with tunable porosity, morphologies, and functions, such as carbon nanotubes (CNT) or carbon nanofibers (CNF), into integrated structures is of great interest, as it allows the development of novel nanosystems with high performances in filter applications and catalysis. In the present work, we report on a low temperature chemical fusion (LTCF) method to synthesize a self-macronized carbon nanotubes foam (CNT-foam) with controlled size and shape by using CNT as a skeleton, dextrose as a carbon source, and citric acid as a carboxyl group donor reacting with the hydroxyl group present in dextrose. The obtained composite has a 3D pore structure with a high accessible surface area (>350 m² g⁻¹) and tunable meso- and macro-porosity formed by the addition of a variable amount of ammonium carbonate into the starting mixture followed by a direct thermal decomposition. The as-synthesized CNT-foam also exhibits a relatively high mechanical strength which facilitates its handling and transport, while the nanoscopic morphology of the CNT significantly reduces the problem of diffusion and contributes to an improvement of the effective surface area for subsequent applications. These CNT-foams are successfully employed as selective and recyclable organic absorbers with high efficiency in the field of waste water treatment.