Synthesis of Ag–Ni core–shell nanowires and their application in anisotropic transparent conductive films

Abstract

We report a modified two-step method for the synthesis of highly dispersed and conductive Ag–Ni core–shell nanowires. The conductivity of the nanowire networks was improved by thermal treatment under various atmospheres. H₂-thermal treatment shows superior enhancement on electrical conductivity and reduces the sheet resistance by nearly seven orders of magnitude relative to that of the pristine networks. X-Ray photoelectron spectroscopic analysis reveals that the metallic Ni⁰ fraction on the surface is more important to the electrical conductivity than the amount of Ni on the surface. The transparent conductive films of Ag–Ni nanowires have a sheet resistance of 220 Ω sq⁻¹ at a transmittance of 75%, much better than those made from the pure Ni nanowires. The Ag–Ni nanowires were aligned easily by applying an external magnetic field; the anisotropic conductivity ratio for the corresponding transparent conductive films can be larger than 10⁵. The good performance may be attributed to the fact that the as-prepared nanowires possess moderate saturation magnetization and low coercivity, alleviating the aggregation of nanowires and favoring the nanowire alignment.