In order to study the cathodic protection of type 304 stainless steel (type 304 SS) by sol-gel derived TiO
2 coating under illumination of light, the photoelectrochemical behavior of TiO
2/type 304 SS system was investigated. During both the dipping and subsequent heat treatment procedures, the compositional elements of type 304 SS were found to be included into the TiO
2 coating, especially Fe involvement being much more intense than the other elements, which greatly decreased the photoeffect of TiO
2 coating. To avoid Fe involvement, a passivation treatment with HNO
3 solution was performed before TiO
2 coating, resulting in the formation of a Cr enriched passive film on the type 304 SS. This Cr enrichment in the passive film retarded the Fe involvement during the TiO
2 coating process, and enabled the TiO
2/type 304 SS specimens to exhibit remarkably less noble photopotentials when the heating temperature was 400°C. Under the optimum conditions for the HNO
3-treatment and TiO
2 coating, the feasibility of cathodic protection for type 304 SS by TiO
2 coating under illumination was clearly demonstrated, as the photopotentials of TiO
2/type 304 SS in neutral chloride solutions were much less noble than the critical repassivation potential for crevice corrosion of type 304 SS.
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