Redox-mediated in-situ fabrication of nanoparticle-packed porous Ag films with excellent surface-enhanced Raman scattering performance

Abstract

Smooth Ag substrate achieved in-situ conversion to form nanoporous architecture that is assembled by highly dispersed nanoparticles (NPs) with a mean size of 21.88 nm by applying a redox potential signal in an alkaline solution with an appropriate pH range. The detailed phase constitution and microstructure evolution process of the Ag substrate induced by the electrochemical redox tuning approach were systemically investigated. Under the action of controllable redox potentials, the smooth Ag substrate is firstly electrochemically oxidized to form Ag2O with an expansion on the unit volume, followed by electrochemical reduction back to metallic Ag, causing the cell volume to shrink. The expansion and contraction of the unit volume during the highly reversible electrochemical process lead to in-situ formation of the highly porous Ag architectures. The fabricated Ag NPs-packed electrode exhibits as an excellent surface-enhanced Raman scattering (SERS) performance, and the measured Raman spectrum of Rhodamine 6G (R6G) reaches a detection limit of 5.44×10−10 mol/L.