Thermal Annealing of Polycatecholamine Coated Carbon Nanotube: A New Path for Copper-Carbon Nanotube Composites Fabrication

Abstract

In present days, the continuous miniaturization of electronic devices comes along with a problematic reduction of their life-time. This is due to the underlying current density being operated increasingly close to the maximum current-carrying capacity (ampacity) of the materials (copper, gold...) used in the conduction channels of micro-circuitry. In this respect, there is a growing attention for new materials with higher ampacity, and copper-carbon nanotube (CNT) composites could constitute a promising alternative. The interest of such copper-carbon composites relies on the combination of the complementary properties of both materials: the high conductivity of copper and the high ampacity of CNT.However, the fabrication of an efficient Cu-CNT composite still remains a huge challenge and, up to now, the metal filling of a CNT hydrophobic matrix using electrochemical methods systematically requires an organic solvent based solution, which is not industrially and ecologically friendly. This constitutes an important drawback of those types of fabrication paths.A new promising way to fabricate such a composite by electrochemistry is shown in our work (see figure 1). It is based on a copper doped polycatecholamine coating of CNT. The coated CNT are deposited to form a matrix and the interstices between CNT are then filled with metallic copper by using an electrochemical step in aqueous solution.In this context, it is relevant to study how the coating impacts the CNT surface conductivity. In this respect, we characterize the CNT coating resistance before and after thermal annealing using C-AFM. Combined SEM and STEM images show the apparition of well dispersed nanoparticles on the CNT surface after thermal annealing. The change of nuclei density and their size distribution is also characterized in function of the annealing temperature. Finally, we use XPS and DSC to show that annealing of copper doped polycatecholamine coated CNT is, in fact, able to promote the reduction of Cu(II) into Cu(I) and Cu(0). Figure 1