Dose-dependent isotherm of Kr adsorption on heterogeneous bundles of closed single-walled carbon nanotubes

Abstract

Équipe 104 : NanomatériauxInternational audienceWe present 77 K isotherms of krypton adsorption on bundles of closed highly-pure HiPco single-walled carbon nanotubes (SWCNTs). Two volumetric adsorption protocols were used, one with an increasing Kr dose per injection (IAD), one with a constant dose (CAD). Detailed microstructural examination showed that the SWCNTs combine into small bundles (of 25-30 SWCNTs) which are heterogeneous in diameter with a consequential range of interstitial channel (IC) shapes and sizes. The IC-sites are the subnanoscaled pores with alternating enlargements and constrictions along the tube axes. This results in adsorption dosing (AD) dependent characteristics of the low-pressure region of the isotherm. In the IAD protocol the switch-back behavior of the isotherm stemmed from metastable adsorption. Using the CAD protocol, different branches are observed. Well-pronounced substeps were established which we interpret as corresponding to the formation of various phases of confined Kr with different atoms arrangement. The height of a given substep obtained in different measurements depends on the AD value which can strongly influence the population of the site. Some substeps existing only for certain values of AD suggests the existence of a certain selectivity or of a preferential phase formation according to this value

Carbon Nanotubes for Mechanical Sensor Applications

“…Morphologies (own artwork) of different CNT solids from single CNTs via CNT bundles (or ropes, fibers, yarns) to CNT networks and thin films in a homologue series of their increasingly complex order: top view (upper row), cross section (center row), and estimated prevalence of intrinsic versus extrinsic sensor effects (lower row). Cross sections and respective terminology according to Zhang et al, Tsareva et al ., and Muris et al…”

“…For a description of the structural organization of as‐produced CNT bundles, Tsareva et al suggested swCNT bundles as quasi‐1D structures with arrays of four different possible adsorption sites . In relation to the earlier models by Williams and Eklund and Muris et al, these authors discriminate between the exohedral surface with external grooves that separate two adjacent outer tubes, the endohedral (or inner) channels of the tubes, and interstitial channels ( cf.…”

Photosensitive Field‐Effect Transistors Made from Semiconducting Carbon Nanotubes and Non‐Covalently Attached Gold Nanoparticles

“…Nanoconjugates (or: hybrids) made from low‐dimensional carbon nanomaterials such as semiconducting single‐walled carbon nanotubes (SWCNTs) and transition metal and/or metal oxide nanoparticles (NPs) have received considerable interest in science and technology as nanoscopic solid‐state building blocks that enable such disruptive nanoelectronic sensor solutions with a high fidelity, sensitivity, and specifity . In such devices, semiconducting SWCNTs can act as a versatile channel material for nanoelectronic transistors (carbon‐nanotube field‐effect transistors: CNT‐FETs) as single or individualized carbon nanotubes (CNTs), aligned as oriented networks, or CNT superstructures in bundles, fibers and ropes, or composite network films . In this work, we outline a method for the fabrication of arrays of CNT‐FETs functionalized with gold nanoparticles as photosensitive or perspectively photochemosensitive field‐effect transistors.…”