Study on the corrosion behavior of copper coupled with TiO2 with different crystal structures

Highlights: • The influences of TiO₂ on copper corrosion depend on TiO₂ crystal structures. • Anatase TiO₂ exhibits corrosion-promotion activity, while rutile TiO₂ does not. • Both crystal type and morphology of TiO₂ affect the "activity" of TiO₂ on copper. • Work function difference between TiO₂ and copper dominates corrosion process. • Electrical conductivity and ORR activity of TiO₂ also affect corrosion process. The influences of semi-conductive TiO₂ with different crystal structures on the initial corrosion behavior of copper in dark conditions were investigated. Results showed that anatase TiO₂ showed "corrosion-promotion activity" to copper, while rutile TiO₂ did not. It is revealed that the "corrosion-promotion activity" is associated with TiO₂ crystal structure and mainly dominated by the work function of TiO₂. When the work function of n-type TiO₂ is higher than that of copper, electrons are inclined to transfer from copper to TiO₂. In addition, higher electrical conductivity and oxygen reduction reaction activity of TiO₂ facilitate the electron consumption at the TiO₂/electrolyte interface.