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

Abstract

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/cm2 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 (icorr) than that of bare copper.

A highly efficient In2S3/Ag2S/TiO2 NTAs photoelectrodes for photocathodic protection of Q235 carbon steel under visible light

“…However, their low utilization rate of Sunlight and high recombination rate of photogenerated carriers restrict their applications. So far, various methods including compounding with narrow bandgap semiconductors (such as CdS [11], PdS [12], CdTe [13] and CdSe [14]), doping metal (such as Cu [15], Zn [16] and Nb [17]) or nonmetal elements (such as W [18], N [19] and B [20]) have been applied to broaden the light absorption region of TiO 2 and enhance its photoelectric conversion efficiency.…”