| Abstract
| - Metal corrosion was successfully prevented using a TiO2-based photoelectrochemical system. Under UVillumination, a TiO2 electrode in a hole scavenging medium supplied photogenerated conduction band electronsto an electrically connected steel electrode with the generation of photocurrent and shifted the coupled potentialto much more negative values. In this galvanic pair, the steel and the TiO2 electrode acted as a cathode anda photoanode, respectively, which is essentially a variation of cathodic protection. The performance of thephotocathodic protection depended little on the light intensity as long as there were enough photons tocompensate for the dark corrosion current of the steel. The shiny surface of the steel electrode remainedintact in a corrosive electrolyte solution as long as it was connected to the UV-illuminated TiO2 photoanode,but it quickly corroded and was covered by red-brown rust in the absence of light. An outdoor test undersolar light also showed a similar effect of corrosion prevention, which verified the possibility of using solarlight for corrosion prevention. Although formate was useful as a hole scavenger, pure water without anyadded hole scavenger was also successful in protecting metal. The performance of the ZnO photoanode wassimilar to that of TiO2. Various experimental parameters affecting the new photocathodic protection systemwere investigated and are discussed.
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