Template-Free Electroless Plating of Gold Nanowires: Direct Surface Functionalization with Shape-Selective Nanostructures for Electrochemical Applications

Metal nanowires (NWs) represent a prominent nanomaterial class, the interest in which is fueled by their tunable properties as well as their excellent performance in, for example, sensing, catalysis, and plasmonics. Synthetic approaches to obtain metal NWs mostly produce colloids or rely on templates. Integrating such nanowires into devices necessitates additional fabrication steps, such as template removal, nanostructure purification, or attachment. Here, we describe the development of a facile electroless plating protocol for the direct deposition of gold nanowire films, requiring neither templates nor complex instrumentation. The method is general, producing three-dimensional nano-wire structures on substrates of varying shape and composition, with different seed types. The aqueous plating bath is prepared by ligand exchange and partial reduction of tetrachloroauric acid in the presence of 4-dimethylaminopyridine and formaldehyde. Gold deposition proceeds by nucleation of new grains on existing nanostructure tips and thus selectively produces curvy, polycrystalline nanowires of high aspect ratio. The nanofabrication potential of this method is demonstrated by producing a sensor electrode, whose performance is comparable to that of known nanostructures and discussed in terms of the catalyst architecture. Due to its flexibility and simplicity, shape-selective electroless plating is a promising new tool for functionalizing surfaces with anisotropic metal nanostructures.