Synthesis of silver microfibers with ultrahigh aspect ratio by galvanic replacement reaction

The efficient galvanic replacement protocol for fabrication of pentagonal silver microfibers with ultrahigh aspect ratio without employing capping agents, surfactants and stabilizers was successfully developed. Silver microfibers of more than 2 cm long and 6600 aspect ratio were grown within 48 h. The influences of precursors on the generation of Ag microfiber during the galvanic reaction were systematically investigated. Concentration of Ag+ is a crucial parameter for the morphological control of the obtained silver microstructures (dendrites, pentagonal rods, microcubes and fibers). The kinetic growth transforms into thermodynamic growth when the concentration was increased from 0.005 M to 0.1 M. Nitrate ions facilitate the galvanic replacement reaction by promoting electron liberation from sacrificial aluminum metal. The obtained microfibers possess nano-interception provides the formation of hotspots within a fiber bundle, thereby presenting a promising substrate for surface enhanced Raman scattering (SERS).