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Benzotriazole Adsorption and Inhibition of Cu(100) Corrosion in HCl: A Combined in Situ STM and in Situ FTIR Spectroscopy Study

1998; American Chemical Society; Volume: 102; Issue: 30 Linguagem: Inglês

10.1021/jp981216e

1520-6106

Monika Vogt, Richard J. Nichols, Olaf M. Magnussen, R. Jürgen Behm,

Electrodeposition and Electroless Coatings

The adsorption and the corrosion inhibiting effect of benzotriazole (BTAH) on Cu(100) electrodes in 0.1 M HCl were investigated using in situ STM, in situ FTIR spectroscopy, and electrochemical measurements. In the double-layer range up to potentials of −0.6 V vs SCE a Cu surface morphology with extended, atomically flat terraces, separated by almost randomly oriented steps, and a low Cu surface mobility are observed by STM. High-resolution STM images reveal a commensurate superstructure in this potential range, which is attributed to a chemisorbed adlayer of BTAH molecules. At potentials around −0.6 V this structure is replaced by a c(2 × 2) Cl- adlayer, which has the same atomic and long-range structure as found in BTAH-free HCl solution. Upon further potential increase to potentials >−0.35 V STM experiments and polarization measurements indicate the onset of Cu dissolution, while the surface is still covered by the c(2 × 2) Cl- adlayer. At slightly higher potentials (>−0.3 V) STM, IR, and electrochemical data point to the formation of a thick, inhibiting Cu(I)BTA film on the Cu surface. The pronounced differences of the BTAH adsorption behavior to that found in H2SO4 solution provide a microscopic explanation for the reduced inhibition efficiency of BTAH in the presence of chloride.