Improved galvanic replacement growth of Ag microstructures on Cu micro-grid for enhanced SERS detection of organic molecules

Galvanic growth of Ag nano/micro-structures on Cu micro-grid was systematically studied for surface-enhanced Raman scattering (SERS) applications. Detailed characterizations via FE-SEM and HR-TEM showed that processing parameters, (reaction time, Ag+ concentration, and PVP addition) all substantially affect thermodynamics/kinetics of the replacement reaction to yield substrates of significantly different microstructures/homogeneities and thus varied SERS performances (sensitivity, enhancement factor, and reproducibility) of the Ag substrates in the detection of R6G analyte. PVP as an additive was shown to notably alter nucleation/growth behaviors of the Ag crystals and promote the deposition of dense and uniform Ag films of nearly monodisperse polyhedrons/nanoplates through suppressing dendrites crystallization. Under optimized synthesis (50 mM of Ag+, 30 s of reaction, and 700 wt.% of PVP), Ag substrates exhibiting a high Raman signal enhancement factor of similar to 1.1 x 10(6) and a low relative standard deviation of similar to 0.13 in the repeated detection of 10 mu M R6G were obtained. The facile deposition and excellent performance reported in this work may allow the Ag microstructures to find wider SERS applications. Moreover, growth mechanisms of the different Ag nano/micro-structures were discussed based on extensive FE-SEM and HR-TEM analysis. (C) 2015 Elsevier B.V. All rights reserved.