Surface-Enhanced Raman Scattering and Atomic Force Microscopy of Brass Electrodes in Sulfuric Acid Solution Containing Benzotriazole and Chloride Ion

Abstract

Three different methods were used to roughen brass (Cu/Zn = 67/33) electrodes in 0.5 M H₂SO₄ containing 1.0 mM benzotriazole (BTAH): (1) polarization at +0.05 V vs. saturated calomel for 5 min; (2) immersion in the above solution for six hours; and (3) oxidation-reduction cycling in the presence of chloride ion. The surfaces prepared by the first two methods exhibited surface-enhanced Raman scattering (SERS) spectra of the polymeric complex [Cu(I)BTA] _n . The SERS spectrum obtained from electrodes prepared by the third method is very similar to that of [CU(I)C1BTAH]₄. Examination of the electrodes by atomic force microscopy (AFM) showed that a large number of grain boundary sites are formed by the roughening processes. This effect is attributed to the loss of zinc, which occurs during corrosion of the mirror-like, polished brass electrode surface in the sulfuric acid solution.