Enhanced photoelectrochemical cathodic protection performance of TiO2 nanotubes based photocatalyst via synergetic effect of graphene and Co(OH)2 dopants

Author(s): Xiayu Lu and Li Liu

 Steel materials used in marine environments are vulnerable to corrosion, especially localized corrosion due to the presence of chloride in such environments. Many methods have been developed to protect steel from corrosion in marine environments, including coatings and cathodic protection using sacrificial anodes. Since Tsujikawa and Fujisawa first discovered that TiO2 could be used as a kind of photoelectrochemical cathodic protection material to protect steel materials, photoelectrochemical cathodic protection method has attracted considerable attention because of its energy conservation and environmentally friendly features.

In this work, we successfully inserted a layer of graphene sheets at the interface between Co(OH)2 nanoparticles and TiO2 nanotubes, aiming to improve the photoelectrochemical performance of the large-band gap semiconductor TiO2 nanotubes. Surface morphology, crystalline structure, optical properties and photoelectrochemical performance of the Co(OH)2/GR/TiO2 photoanodes were comparatively investigated. In particular, the photoelectrochemical performance of the Co(OH)2/GR/TiO2 photoanode as well as the cathodic protection performance when coupled with 304SS in 3.5 wt.% NaCl solution were also carefully investigated and analyzed in order to deduce the process mechanisms and identify any synergistic effects between the anode materials.

Compared with the blank TiO2, Co(OH)2/TiO2 and GR/ TiO2 photoanodes, the photo-absorption performance, photoelectrochemical performance of Co(OH)2/GR/TiO2 photoanode were the best which is mainly due to the good electron conduction of graphene and the hole trapping effect of Co(OH)2 and their positive synergistic effect. As a result, Co(OH)2/GR/TiO2 photoanode produced an effective photocathodic protection for 304SS

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