Centimeter-scale high nanoscale roughness silver nanoparticles decorated silver nanowires: A highly sensitive material towards melamine in milk

Abstract Centimeter-scale high nanoscale roughness silver nanoparticles (AgNPs) decorated silver nanowires (AgNWs) has been developed by vacuum thermal evaporation method and solid-state ionics method at 3 μA direct-current electric field (DCEF) with fast ionic conductor KAg4I5 films. The surface morphologies, microstructures and chemical compositions of the AgNPs/AgNWs were characterized. The fractal dimensions of centimeter-scale AgNPs/AgNWs was calculated by grid covering method and the surface-enhanced Raman scattering (SERS) performance was detected by melamine milk solution as probe molecules. The results show that the macroscopic dendritic AgNPs/AgNWs with the longest length of 4.1 cm were prepared, the diameters of AgNPs/AgNWs changed from 30 nm to 90 nm and many 10–40 nm AgNPs existed on the prepared nanostructures, which lead to high nanoscale roughness AgNPs/AgNWs. The fractal dimensions of AgNPs/AgNWs was 1.59 because of more dentritic nanostructures and the limiting concentration of melamine in liquid milk for the prepared SERS substrates is 10−10 mol/L, which is far below the American and Chinese strictest safety limits required of melamine in milk. These results show that the prepared AgNPs/AgNWs with high nanoscale roughness, simple detection procedure, facile material synthesis and low detection concentration has strong and promising application prospect for SERS detection in food safety fields.