Photocathodic protection properties of NiP/TiO₂ bilayer coatings by a combined electroless plating and sol–gel method

Abstract

A combined electroless plating and sol-gel method was developed for preparing a NiP/TiO 2 bilayer coating to achieve an especial photocathodic protection effect for A3 low carbon steel. Photocathodic protection properties of the coating were investigated by the electrochemical method. Surface morphology and structure of the coating were characterized by scanning electron microscope (SEM) and X-ray diffraction (XRD). The results show that the open circuit potential (OCP) of the NiP/TiO 2 coating electrode shifts to À0.42 V under UV irradiation, which is lower than the corrosion potential of A3 low carbon steel. When the light is turned off, the photocathodic protection effect cannot be maintained. In addition, the mechanism of photocathodic protection for the coating was also explored.

Review—Photoelectrochemical Cathodic Protection in The Dark: A Review of Nanocomposite and Energy-Storing Photoanodes

“…159 Contrary to this, a few studies reported on various Ni-based coatings/photoanodes did not reveal considerable storage effect. [160][161][162] The absence of dark protection with a reported NiP/TiO 2 bilayer coating can be due to the more active mild steel cathode used in the study. 160 The lack of dark protection in Ni-doped TiO 2 161 and NiSe 2 -TiO 2 162 photoanodes was attributed to the fast recombination kinetics.…”

Photocathodic protection properties of TiO2–V2O5 composite coatings

“…Recently, the application of the TiO 2 coatings to photocathodic protection of metals has inviting prospects and has drawn the considerable attention of corrosion researchers 9–18. In the area of photocathodic protection, some marked progresses have already been made in preparing TiO 2 coatings and researching their photo‐electronchemical properties.…”