Local Effects of Organic Inhibitor Molecules on Passivation of Grain Boundaries Studied In Situ on Copper

The effects of two organic corrosion inhibitors, 2-mercaptobenzothiazole (MBT) and 2-mercaptobenzimidazole (MBI), on grain boundary passivation was investigated copper at the nanometer scale in NaOH solution using electrochemical scanning tunneling microscopy (ECSTM). Global analysis by cyclic voltammetry showed that surface layers, pre-formed after reductive dissociation native oxide presence block formation a Cu(I) thus passivation, but do not entirely suppress residual reactivity. Local ECSTM initial metallic, subsequently oxidized, final reduced states confirmed intergranular reactivity except for coherent twins. On coincidence site lattice (CSL) random boundaries, dissolution with accumulation products or observed, depending barrier effect inhibitor layer formation. For low ? CSLs, no difference observed between MBT MBI. more reactive high CSLs pre-adsorbed formed stronger against growth than results provide deeper understanding how is altered inhibitor, including locally different types.