Scanning electrochemical microscopy for the investigation of corrosion inhibition of triazino-benzimidazole-2-thiones in hydrochloric acid solution

Aryl-triazino-benzimidazole-2-thiones were synthesized via three-component reaction between ammonium thiocyanate, benzoyl chlorides, and 2-aminobenzimidazole in acetone. The structure of the products was confirmed by NMR, FT‐IR, and mass spectrometer. The corrosion behaviors of these compounds on carbon steel in 2 M HCl solution were investigated by scanning electrochemical microscopy, operated in the substrate-generation/tip-collection mode using Fe2+/Fe3+ redox couple as redox mediator. The tip current values and local ferrous ion concentrations were obtained. The inhibition efficiency of the inhibitors was investigated by weight loss measurements. When the inhibition efficiency was more than 85 %, scanning electrochemical microscopy and weight loss measurements were in good agreement.