Enhancing the Stability of Copper Nanowires via 2D MXene Surface Coating

Abstract

Copper nanowires (CuNWs) are a promising material for flexible, transparent electronics. CuNWs showcase mechanical flexibility and conductivity, which is comparable to that of silver nanowires, along with cost-effectiveness. However, the long-term applications of CuNWs are directly affected by oxidation, which induces surface degradation, thereby diminishing the material's environmental resistance. In this thesis, we have developed a Copper nanowire-MXene nanocomposite (Cu-MXene) via a 2-step method to enhance the lifetime of the CuNWs by protecting them from oxidation. MXenes are a class of two-dimensional (2D) transition metal carbides which exhibit outstanding electrical conductivity, hydrophilicity and chemical stability, making them an ideal candidate for CuNWs protection. In this study, CuNWs were synthesised using a hydrothermal method using D- (+)-glucose as a reducing agent and hexadecyl amine as a capping agent to control the nanomaterial morphology and aspect ratio. The as-prepared CuNWs were incorporated with MXene (Ti3C2TX, where X is O, OH, F, etc.) via adsorption at low temperature (<5 ○C), establishing interfacial interactions between CuNWs and Ti3C2TX. The structural, morphological and chemical properties of the Cu-MXene composite were determined using Scanning electron microscopy (SEM), Transmission electron microscopy (TEM), X-ray diffraction (XRD), and X-ray photoelectron spectroscopy (XPS). The electrical conductivity and oxidation resistance were determined using four-probe and degradation studies over time, respectively. The electron microscopies reveal the formation of ultralong CuNWs, with a diameter of 60 ± 0.3 nm and >100 μm long. The combined characterisation results demonstrate strong interfacial interactions between MXene and CuNWs, encompassing both physical and conformal contact and electrical bridging. Degradation studies further reveal that MXene serves as an effective protective layer against oxidation. This thesis introduces an MXene-based strategy to enhance CuNW durability and paves the way for optimised composites and device integration.