Effects of supercritical-CO2 treatment on the pore structure and H2 adsorptivity of single-walled carbon nanohorns

• Published in: Carbon Letters Vol. 34; no. 9; pp. 2317 - 2323
• Main Authors: Kim, Nam Ryeol, Wee, Jae-Hyung, Kim, Chang Hyo, Kim, Dong Young, Kaneko, Katsumi, Yang, Cheol-Min
• Format: Journal Article
• Language: English
• Published: Singapore Springer Nature Singapore 01.11.2024; 한국탄소학회; Springer Nature B.V
• Subjects: Adsorption; Adsorptivity; Aggregates; Carbon; Carbon dioxide; Characterization and Evaluation of Materials; Chemistry and Materials Science; Diffusion rate; Graphene; Graphite; High resolution electron microscopy; Materials Engineering; Materials Science; Molecular structure; Nanomaterials; Nanotechnology; Original Article; Physical characteristics; Porosity; Selective adsorption; Transmission electron microscopy; 자연과학일반; Supercritical-CO; treatment; adsorption; Single-walled carbon nanohorn; Pore structure; H; Interstitial pore; Supercritical-CO2 treatment; H2 adsorption
• ISSN: 1976-4251; 2233-4998
• DOI: 10.1007/s42823-024-00757-7

We investigated the effects of supercritical-CO 2 treatment on the pore structure and consequent H 2  adsorption behavior of single-walled carbon nanohorns (SWCNHs) and SWCNH aggregates. High-resolution transmission electron microscopy and adsorption characterization techniques were employed to elucidate the alterations in the SWCNH morphology and aggregate pore characteristics induced by supercritical-CO 2 treatment. Our results confirm that supercritical-CO 2  treatment reduces the interstitial pore surface area and volume of SWCNH aggregates, notably affecting the adsorption of N 2 (77 K), CO 2 (273 K), and H 2 (77 K) gasses. The interstitial porosity strongly depends on the supercritical-CO 2 pressure. Supercritical-CO 2  treatment softens the individual SWCNHs and opens the core of SWCNH aggregates, producing a partially orientated structure with interstitial ultramicropores. These nanopores are formed by the diffusion and intercalation of CO 2 molecules during treatment. An increase in the amount of H 2 adsorbed per interstitial micropore of the supercritically modified SWCNHs was observed. Moreover, the increase in the number and volume of ultramicropores enable the selective adsorption of H 2 and CO 2 molecules. This study reveals that supercritical-CO 2 treatment can modulate the pore structure of SWCNH aggregates and provides an effective strategy for tailoring the H 2  adsorption properties of nanomaterials.