Fractal theory study and SERS application of gold nanoparticles decorated centimeter level copper nanowire detectors

Abstract

Gold nanoparticles (AuNPs) decorated centimeter level copper nanowires (CuNWs) were prepared by a solid-state ionics method under 8 μA direct current electric field (DCEF) using fast ionic conductor Rb4Cu16Cl13I7 films and vacuum thermal evaporation method. The surface morphology and chemical composition of the AuNPs/CuNWs were characterized by scanning electron microscopy (SEM) and energy dispersive spectrometer (EDS), respectively. The fractal dimension of the AuNPs/CuNWs was calculated by fractal theory and the Raman enhancement performance was detected by Rhodamine 6G (R6G) aqueous solutions. The results indicate that the AuNPs/CuNWs arranged neatly near cathode were long-range disorder and short-range order with the longest length of 6 cm were prepared by a solid-state ionics method and vacuum thermal evaporation method. The diameters of CuNWs ranged from 20 to 60 nm and many regularly arranged AuNPs with the diameter from 5 to 10 nm lie in the prepared nanostructures, which lead to the AuNPs/CuNWs have high surface roughness. The fractal dimension of AuNPs/CuNWs was 1.242, which indicated that there were less dentritic nanostructures in the whole growing nanostructures and the growth mechanism of AuNPs/CuNWs was associated with apical growth advantage. The limiting concentrations of R6G for the prepared high surface roughness AuNPs/CuNWs SERS substrates is 10−14 mol/L.