High roughness gold nanoparticles/silver nanowires composites: Fabrication, characterization and ultrasensitive SERS detection towards Rhodamine B

Abstract

A novel centimeter-scale gold nanoparticles (AuNPs)/silver nanowires (AgNWs) composites surface-enhanced Raman scattering (SERS) substrates prepared by vacuum thermal evaporation and solid-state ionics method at 9 μA direct-current electric field (DCEF) with fast ionic conductor KAg4I5 films was reported. The surface morphologies, microstructures and chemical compositions of the AuNPs/AgNWs composites were characterized. The fractal dimensions of centimeter-scale AuNPs/AgNWs composites was calculated by grid covering method and the SERS performance was detected by Rhodamine B (RB) aqueous solution as probe molecules. The results show that the macroscopic dendritic AuNPs/AgNWs composites with the longest length of 5 cm were prepared, the diameters of AuNPs/AgNWs composites changed from 50 nm to 100 nm and many 20–50 nm AuNPs existed on the prepared nanocomposites, which lead to high nanoscale roughness AuNPs/AgNWs composites. The molar ratio of Ag:Au is 28.67:1 and the fractal dimensions of AuNPs/AgNWs composites was 1.67 because of more dentritic nanocomposites. The limiting concentration of RB for the prepared SERS substrates is 10−15 mol/L, which is far below the strictest safety limits required of RB in China. These results show that the prepared AuNPs/AgNWs composites with high nanoscale roughness, facile material synthesis, low detection concentration and simple detection procedure has strong application prospect in food safety.