Fabrication of Hierarchical N-doped Carbon Nanotubes for CO2 Adsorption

Hierarchical N-doped carbon nanotubes (NCTs) with controllable aspect ratios were developed for CO 2 adsorption. In this work, NCTs were synthesized by coating different amounts of 3-aminophenol/formaldehyde resin (APF) on the outer layer of silica nanotubes, carbonizing in N 2 at 700 ∘ C and removing the silica and Ni template by hydrofluoric acid etching. The obtained NCTs were activated by K 2 CO 3 . After activation, micropores on the activated N-doped carbon nanotubes (ANCTs) were enriched, the micro-surface area and pore volume of ANCT-1.0 reached 1195 m 2 g − 1 and 0.45 cm 3 g − 1 , respectively, and the corresponding adsorption capacity increased by 50% (4.50 mmol g − 1 at 0 ∘ C and 1 bar). Moreover, ANCT-1.0 maintained a high stability throughout consecutive adsorption–desorption cycles. The advantages of hierarchical N-doped carbon nanotubes, including their meso–microporous structures, high geometric aspect ratio and good stability, make them valuable and promising materials to capture carbon dioxide.