Chemical Bond Formation between Vertically Aligned Carbon Nanotubes and Metal Substrates at Low Temperatures

Abstract

The exceptional physical properties of carbon nanotubes (CNTs) have the potential to transform materials science and various industrial applications. However, to exploit their unique properties in carbon-based electronics, CNTs regularly need to be chemically interfaced with metals. Although CNTs can be directly synthesized on metal substrates, this process typically requires temperatures above 350 °C, which is not compatible for many applications. Additionally, the CNTs employed here were highly densified, making them suitable as interconnecting materials for electronic applications. This paper reports a method for the chemical bonding of vertically aligned CNTs onto metal substrates that avoids the need for high temperatures and can be performed at temperatures as low as 80 °C. Open-ended CNTs were directly bonded onto Cu and Pt substrates that had been functionalized using diazonium radical reactive species, thus allowing bond formation with the open-ended CNTs. Careful control during grafting of the organic species onto the metal substrates resulted in functional group uniformity, as demonstrated by FT-IR analysis. Scanning electron microscopy images confirmed the formation of direct connections between the vertically aligned CNTs and the metal substrates. Furthermore, electrochemical characterization and application as a sensor revealed the nature of the bonding between the CNTs and the metal substrates.

Chemically Bonded Carbon Nanotube Film to a Nanostructured Gold Electrode for Electrochemical Sensing of Hydrogen Peroxide

“…Carboxyl-functionalized CNT film and amine-functionalized Au surface were clamped to promote chemical bonding between CNT and Au (to form Au-L-CNT). A detailed description of the process is described in our previous work . The schematics of electrode fabrication are shown in Figure .…”

“…To take advantage of the physical properties of aligned CNT even further, a covalent attachment to a metal substrate can be used. Grafting of the Au surface by diazonium salts with covalent Au–C bond formation has been previously shown. − The introduction of aryl group linkers allows for the further surface functionalization with CNT . Such a modification can provide additional mechanical robustness and create directed efficient electron transport pathways.…”

“…38−41 The introduction of aryl group linkers allows for the further surface functionalization with CNT. 42 Such a modification can provide additional mechanical robustness and create directed efficient electron transport pathways. Compared to physical adsorption, covalent attachment of CNT to Au prevents mechanical degradation of the electrode, making the sensing element more robust and the detected signal more stable.…”

Sidewall Chemical Bonding of Aligned Carbon Nanotubes with Metals: A Promising Route for Hybrid Materials Development

“…21 However, the cost of and potential damage caused by such high-temperature treatments make the use of linker molecules to chemically bond CNTs to metal surfaces at reasonably lower temperatures a more promising approach for practical applications. 22 Linker molecules as bridging agents may also aid in overcoming the energy mismatch between CNTs and metals, thus providing a low-cost method for forming chemical bonds between CNTs and metals under mild conditions. Theoretical studies have shown that CNT−linker−metal structures provide better interface conductivity than mere physical metal−CNT interactions.…”

“…In addition, induction heating of a Au–CNT interface can reduce the contact electrical resistance by up to 99% . However, the cost of and potential damage caused by such high-temperature treatments make the use of linker molecules to chemically bond CNTs to metal surfaces at reasonably lower temperatures a more promising approach for practical applications . Linker molecules as bridging agents may also aid in overcoming the energy mismatch between CNTs and metals, thus providing a low-cost method for forming chemical bonds between CNTs and metals under mild conditions.…”