| dc.description.abstract | The advent of offshore renewable energy, e.g. wind, wave, and tidal, holds the promise of significant environmental and economic benefits. Once built, the energy produced by offshore renewable energy farms is transmitted to the land by cables installed on the seabed. However, being made of copper, subsea power cables suffer from high density and poor mechanical properties. Recent developments in nanotechnology have provided new alternatives. Among these, carbon nanotubes (CNTs) stand out for their high electrical and thermal conductivity, low density, supreme ampacity and mechanical properties. In here, incorporation of CNT into Cu matrix to fabricate light-weight and highly conductive wires has been evaluated. CNT surface has very poor wettability towards copper. This challenge was overcome by altering the surface chemistry of the CNTs. Results show that by controlling the CNT surface chemistry, one can tune the composition and morphology of the Cu deposits. Cu-CNT thin films were fabricated by using CNT-Cu hybrid structures via vacuum filtering followed by electroless deposition. Electrical conductivity measurements showed that thin films that contained Thiol-CNT have remarkably higher electrical conductivity and denser structure. Accordingly, two routes are undertaken to fabricate Cu-CNT wires. In the first approach, CNT fibers are fabricated via wet-spinning. Surface of the fibers are modified by cysteine and subsequently a layer of Cu is deposited on their surface via electroless deposition, forming a core-shell structure. The electrical conductivity of these fibers is 3.6 ×107 S/m, while their specific strength is twice of copper. In the second approach, CNT-CuNW colloid are mixed with a polymer-Cu salt solution. Subsequently, after electrospinning the precursor polymer is removed by heating at 400 °C in air followed by purging a reforming gas to reduce the fibers into CNT-Cu fibers. These high aspect ratio fibers have a remarkable performance in transparent conductive electrodes. Its sheet resistance reaches to 39 ohm/square at 79% transmittance, outperforming commercial counterparts. Moreover, we found out that by proper interface design of CNTs and Cu oxides through introducing Sn2O intermediate layer, we can produce hybrid structures of CNT and Cu oxides that have specific capacity of 662 F/g and show 94% retention after 5000 cycles. Findings here are versatile and can be used in other metal-CNT structures. | |
