Abstract:

Based on the shell-isolated nanoparticles-enhanced Raman spectroscopy(SHINERS) and naked Au nanoparticles SERS technology, the adsorption behavior of 4-cyanopyridine(4-CNPy) on a TiO₂ electrode was investigated. The difference in the spectral features from SHINERS and SERS was observed. The SHINERS results showed that the adsorption orientation of 4-CNPy changed with the applied potential. At the potential of 0 V, the 4-CNPy molecules adsorbed on TiO₂ electrode by the N atom of pyridine ring in a vertical orientation. With the potential moving to more negative potential, partial molecules turned to a tilted mode. At -1.0 V, the angle of the tilted mode to the vertical line becomes large. At the potential above 0 V, it keeps constant as a vertical orientation by the N atom of pyridine. When the naked Au nanoparticles were attached to the TiO₂ electrode, the obtained spectra were originated from the probe molecules adsorbed on the TiO₂, naked Au nanoparticles and the TiO₂/Au composition. It is difficult to distinguish the contribution of different adsorption sites.

Key words: Shell-isolated nanoparticles-enhanced Raman spectroscopy(SHINERS), 4-Cyanopyridine, Core-shell nanostructures, TiO₂ electrode, SERS spectrum, Adsorption