Synthesis of high aspect ratio copper nanowire using copper oxalate precursor

Recently, metal nanowires have been actively researched as a novel form of conductive material for application in various electronic devices, and Cu nanowire has gained much attention due to its high electrical conductivity and low cost. In this report, we present a study on the synthesis of high aspect ratio and high yield Cu NWs using Cu oxalate as a Cu precursor, which can be differentiated from the conventional approaches. Cu oxalate would be able to minimize the composition change in the reaction solution during the synthesis by generating CO2\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$${\text{CO}}_{2}$$\end{document} gas as a reaction by-product, which is easy to remove during Cu NW synthesis promoting the synthesis of uniform and high aspect ratio Cu NWs. In this work, we successfully demonstrated that the high reduction temperature of Cu oxalate, 250 degrees C, which is considered to be a main limiting factor for the application of Cu oxalate as a Cu precursor, can be effectively reduced to produce Cu-ions at the considerably low temperature, 160 degrees C, by adding ascorbic acid into the reaction solution. In addition, PVP and NaCl were introduced as a capping and mediating agent for the synthesis of high aspect ratio Cu NWs, and the effects of each agent were studied to determine the optimal addition conditions. In this study, various physical and chemical characterizations, including field-emission scanning electron microscopy, X-ray diffractometer, energy-dispersive X-ray spectroscopy, focused ion beam, field-emission scanning transmission electron microscopy, and selected-area electron diffraction analysis, were performed to analyze and evaluate the synthesized Cu NWs, which successfully demonstrated that our novel approach would produce a high aspect ratio Cu NWs, 413, with a diameter of 189 nm and a length of 78 mu m with {110} orientation growth. In addition, the high synthesis yield, 94%, was also achieved in terms of number of NW density. To the best of our knowledge, this is the first study to synthesize Cu NWs by applying Cu oxalate, which is believed to have great potential as a low-cost, high yield, and uniform Cu NW synthesis technology in the future.