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

The promising applications of carbon nanotubes (CNTs) have been limited by several factors, one of which is the lack of robust connections to metal surfaces. In this work, a method for creating chemically covalent bonds with CNTs parallel to a metal substrate was developed by using aligned CNT films. Various metal surfaces, including Cu, stainless steel, Au, indium tin oxide, and Al, were functionalized with an electrically conducting linker molecule that reacts with CNTs bearing carboxyl groups to achieve robust bonding. The chemical nature and robustness of the linker-metal bonding were identified using X-ray photoelectron spectroscopy and infrared spectroscopy following ultrasonication. Scanning electron microscopy showed that the CNT film remained on the metal surface after ultrasonication, confirming the formation of robust chemical bonds. Electrodes based on these hybrid materials exhibited enhanced performance relative to the corresponding bare metal surfaces with improved peak currents observed after CNT modification, suggesting their potential use as sensor electrodes. Finally, electrical conductivity tests with Au electrodes revealed that the CNT-linker-Au interface resistance was almost 1 order of magnitude lower than that of a compression-based contact interface between CNTs and metals.