Synergistic effect of molybdate or tungstate and water soluble thiol on the corrosion protection of copper

An approach to fabricate protective film on copper substrate utilizing molybdate or tungstate assisted by dithiol was proposed. The fabricated films exhibited double-layer structure. The top layer was an organic layer primarily composed of interconnected dithiol molecules through disulfide bonds originating from the oxidation of molybdate or tungstate. The Cu 2 S bottom-layer formed as a result of the cleavage of C-S bonds subsequent to the adsorption of dithiol molecules onto the copper matrix. The molybdate participated the film via MoO x and MoS x . Although no tungstate species were detected in the film, the oxidizing effect of tungstate facilitated a conversion of dithiol molecules into polymers, resulting in a significantly thicker surface layer. The corrosion protection efficiencies of the films reached 99.7 % and 99.8 %, respectively, attributed to the incorporation of molybdate or tungstate additives. Theoretical calculations provided valuable insights into the process of film formation and elucidated the relationship between film structure and anti-corrosion performance.