Enhancement of Photoelectrochemical Cathodic Protection of Copper in Marine Condition by Cu-Doped TiO2

Photochemical cathodic protection (PEC) efficiency was enhanced by doping TiO2 with Cu (Cu/TiO2) through impregnation and reduction under hydrogen. The Cu loading was vaired from 0.1 to 1.0 mol% (0.1 Cu/TiO2, 0.5 Cu/TiO2, 1 Cu/TiO2). Then, up to 50 wt% Cu/TiO2 was mixed with TiO2 to form nanocomposite films. The film photocurrent and photopotential were measured under 1 mW/cm(2) UV irradiation. The Cu/TiO2 film with 10 wt% of 0.5 Cu/TiO2 exhibited the highest photocurrent of 29.0 mA/g, which was three times higher than the TiO2 film. The underlying reason for the high photocurrent was the lower photopotential of film than the corrosion potential of copper for PEC. This film was also applied on copper terminal lug for anti-corrosion measurement by Tafel polarization in 3.5 wt% NaCl solution. The results showed that the photopotential of terminal lug coated with the film was -0.252 V vs. Ag/AgCl, which was lower than the corrosion potential of copper (-0.222 V vs. Ag/AgCl). Furthermore, the film can protect the corrosion of copper in the dark with 86.7% lower corrosion current (i(corr)) than that of bare copper.