Potential Controlled Electrochemical Conversion of AgCN and Cu(OH)₂ Nanofibers into Metal Nanoparticles, Nanoprisms, Nanofibers, and Porous Networks

Nanowires are expected to provide considerable advances in the use of smaller and more efficient sensing, electronic, and photovoltaic devices. Good electrical connections of the nanowires within devices can, however, be problematic. We present here a new method that takes advantage of the available large-scale and reproducible wet-chemical syntheses of non-zero-valent anisotropic nanomaterials. The electrochemical reduction of preformed solid AgCN and Cu(OH)2 nanofibers (NFs) on surfaces allows one to form metallic nanostructures that are integrated in electrical junctions with excellent electrical contacts. Some fundamental aspects of the electrochemical reduction of AgCN NF are presented, including their redox potential and propagation of the metal boundary formed during the electrochemical reduction process. The clear connection between native (unreduced) AgCN NF and reduced Ag0 nanostructures is shown. The reduction potential, the nature of the supporting substrate (conductive vs insulating), and the size of the original fibers strongly influence the morphology and dimensions of the Ag0 nanostructures thus produced. A number of different Ag0 nanostructures are electrosynthesized, including nanoprisms, nanoparticles (NPs), and NFs, made from the aggregation of nanoprisms and NPs, and continuous fibers, whose width is tunable between 90 and 500 nm. We report the formation of excellent electrical contact via the electrochemical reduction of metal/Mz+ NF/metal junctions. This technique is simple, fast, and applicable to other materials such as Cu(OH)2 NF. It allows for the formation of electrically connected metallic networks with new interesting geometries, which could be applied to a form of electrochemical welding.