RESUMEN
Silver nanocubes were synthesized by reducing silver nitrate with ethylene glycol in the presence of poly(vinyl pyrrolidone) based on the report by Xia's group. Silver nanocubes were immobilized on silicon wafers by self-assembly processes. SERS activity of silver nanocubes was detected by using pyridine and SCN- respectively as probe molecules. The preliminary results show that the Raman intensities of pyridine and SCN- adsorbed at silver nanocubes were enhanced considerably, indicating that silver nanocubes can be used as a good SERS substrate. On the other hand, SERS combined with the probe molecule method can be used to characterize the optical property of silver nanocubes.
Asunto(s)
Nanopartículas del Metal/química , Compuestos de Plata/química , Plata/química , Espectrometría Raman/métodos , Glicol de Etileno/química , Isotiocianatos/química , Nanopartículas del Metal/ultraestructura , Microscopía Electrónica de Rastreo , Microscopía Electrónica de Transmisión , Povidona/química , Piridinas/química , Compuestos de Plata/síntesis química , Nitrato de Plata/química , Espectrometría Raman/instrumentación , Propiedades de SuperficieRESUMEN
The aim of this work is to further improve the molecular generality and substrate generality of SERS (i.e., to fully optimize the SERS activity of transition-metal electrodes). We utilized a strategy of borrowing high SERS activity from the Au core based on Au-core Pt-shell (Au@Pt) nanoparticle film electrodes, which can be simply and routinely prepared. The shell thickness from about one to five monolayers of Pt atoms can be well controlled by adjusting the ratio of the number of Au seeds to Pt(IV) ions in the solution. The SERS experimental results of carbon monoxide adsorption indicate that the enhancement factor for the Au@Pt nanoparticle film electrodes is more than 2 orders of magnitude larger than that of electrochemically roughened Pt electrodes. The practical virtues of the present film electrodes for obtaining rich and high-quality vibrational information for diverse adsorbates on transition metals are pointed out and briefly illustrated with systems of CO, hydrogen, and benzene adsorbed on Pt. We believe that the electrochemical applications of SERS will be broadened with this strategy, in particular, for extracting detailed vibrational information for adsorbates at transition-metal electrode interfaces.