Shell-isolated nanoparticle enhanced Raman spectroscopy (SHINERS) investigation of benzotriazole film formation on Cu(100), Cu(111), and Cu(poly)

Benzotriazole (BTAH) is well known as an effective corrosion inhibitor for Cu because of its ability to make a coordination polymer film on the surface that provides a barrier to Cu oxidation. BTA ^- film formation was investigated on single-crystal and polycrystalline Cu surfaces with shell-isolated nanoparticle enhanced Raman spectroscopy (SHINERS) using silica-encapsulated Au nanoparticles. Potential-dependent spectra display reversible film formation on polycrystalline Cu and irreversible film formation on single-crystal Cu. Grain boundaries leading to smaller BTA ^--Cu oligomers are proposed to be the reason for cathodic degradation of the BTA ^- polymeric films on polycrystalline Cu.