Synthesis and Characterization of an SWCNT@HKUST-1 Composite: Enhancing the CO₂ Adsorption Properties of HKUST-1

Abstract

Synthesis of a new HKUST-1 composite based on single-walled carbon nanotubes (SWCNTs) was successfully achieved (SWCNT@HKUST-1). SWCNTs were used as templates to grow rod-like HKUST-1 crystals over the surface of the nanotubes. N₂ adsorption properties showed an increment on the surface area and pore volume for the SWCNT@HKUST-1 composite. Furthermore, the CO₂ capture increased, from 7.92 to 8.75 mmol g^-1 at 196 K up to 100 kPa, for the SWCNT@HKUST-1 composite. This enhancement was directly associated with the increase of the surface area of the composite. Additionally, an increase in the CO₂ heat of adsorption was estimated, from 30 to 39.1 kJ mol^-1 for the SWCNT@HKUST-1 composite. In situ Raman experiments corroborated the favored CO₂ adsorption for the composite and provided an insight into the augmented hydrophobicity of the SWCNT@HKUST-1. Ethanol adsorption isotherms corroborated an increase in the hydrophobicity of the material upon the incorporation of carbon nanotubes.