Fabrication of Z-Scheme TiO2/Au/CdS Nanostructured Coating with Enhanced Photocathodic Protection Performance for Carbon Steel

Photocathodic protection technology has presented great potential for protecting stainless steel; however, due to the higher electrochemical activity and more negative corrosion potential of carbon steel, most of them are not applicable to carbon steel. This study has fabricated a series of TiO2/Au/CdS nanostructured coating. The prepared samples have extended light absorbance to the visible light region. Among then, the TiO2/ Au10/CdS nanostructured coatings have successfully offered cathodic protection to carbon steel. The maximum photogenerated potential drop value is -0.591 V, and the photocurrent density is 1.253 mA & BULL;cm-2, which is about 4 times higher than that of TiO2. The active species trapping tests have been performed to reveal that the nanostructured coatings possess a Z-scheme heterojunction property, which supplies an efficient charge separation and demonstrates strong reduction and oxidation abilities. The photocathodic protection mechanism is discussed in detail in the paper.