Surface-enhanced Raman scattering (SERS) on copper electrodes in 1-n-butyl-3-methylimidazoliun tetrafluorbarate (BMI.BF4): The adsorption of benzotriazole (BTAH)

The spectroelectrochemical behavior of a copper electrode in 1-n-butyl-3-methylimidazolium tetrafluoroborate (BMI.BF4) ionic liquid containing benzotriazole (BTAH) has been investigated by cyclic voltammetry and surface-enhanced Raman scattering (SERS). The cyclic voltammograms have shown that in the presence of BTAH there is a considerable decrease in the anodic currents, suggesting that BTAH inhibits the oxidation of copper in BMI.BF4. The SERS results have shown that at potentials positive to the potential of zero charge (PZC) for copper in BMI.BF4, BTAH interacts with the copper(I) on the metal surface leading to the formation of the [Cu(I)BTA]n polymeric film that is responsible for the corrosion inhibition process. At potentials negative to the PZC BTAH adsorbs chemically on the copper surface. This adsorption is characterized by the observation of the ν(Cu-N) stretching mode at 253 cm−1 and by the δ(NH) bending mode near 1115 cm−1.