Electric field-induced adsorption change of 1,3,5-benzenetricarboxylic acid on gold, silver, and copper electrode surfaces investigated by surface-enhanced Raman scattering

The potential-induced adsorption structure of 1,3,5-benzenetricarboxylic acid (trimesic acid TMA) on Au, Ag, and Cu electrode surfaces has been examined by means of surface-enhanced Raman scattering (SERS) in an applied voltage range between −0.6 and 0.6 V. Spectral analyses indicate that TMA is assumed to have a perpendicular geometry with its benzene ring on Au, Ag, and Cu surfaces. The carboxylate band’s strong appearance at ∼1390 cm−1 indicates that TMA should bind to the metal surfaces via its carboxylate group. As the electric potential is shifted from 0.6 to −0.6 V, the adsorption of TMA onto the electrodes’ surfaces appears to change, as indicated by the frequency shift or the change in the vibrational bands’ intensity. As previously reported [B. Han, Z. Li, S. Pronkin, Th. Wandlowski, Can. J. Phys. 82 (2004) 1481], depending on the applied electric field, it seems possible that TMA may form several distinctly different adlayer structures on an Au surface between 0 and 0.4 V. Such a potential-dependent adsorption change depending on the applied electric field is not found to occur on Ag and Cu under our potential region.