SERS on (111) Surface Nanofacets at Pt Nanoparticles: The Case of Acetaldehyde Oxime Reduction

Abstract

This work shows that SERS spectra can be used to monitor a surface reaction that exclusively takes place on certain surface sites of Pt nanoparticles. As an example, the reduction of acetaldehyde oxime (AO) toward ethylamine on platinum in perchloric acid solutions, which is a structure-sensitive process that takes place exclusively on (111) sites, is employed. Spherical and octahedral-tetrahedral Pt nanoparticles were used as SERS-active material. The AO reduction, followed by SERS measurements, was clearly observed on the octahedral-tetrahedral Pt nanoparticles due to their preferential (111) surface orientation. In addition, FTIRS and DFT theoretical calculation analyses were performed. From spectroelectrochemical results and DFT calculations, it is concluded that AO is bonded to the (111) platinum surfaces by the lone pair of the N atom, in a top adsorption configuration, with the molecular plane perpendicular to the metal surface. In addition, SERS spectra also showed that acetonitrile, produced by d...