Study on the Photogenerated Cathodic Protection Effect of Z-Scheme TiO₂/Au/CdS Heterojunction on 304 Stainless Steel

Abstract

For improving the photogenerated cathodic protection performance of TiO2 on 304 stainless steel, TiO2 nanobelts were prepared on the surface of Ti sheet by anodization, TiO2/Au films were prepared by ion sputtering, and finally the Z-type heterojunction TiO2/Au/CdS heterojunction composite films were obtained by successive ionic layer adsorption and reaction methods. Meanwhile, X-ray diffractometer, scanning electron microscope, energy spectrometer, and X-ray photoelectron spectroscopy were used to analyze the crystal structure, surface morphology, element distribution, valence state of each element, and bond energy of the prepared films. A spectrophotometer was used to analyze the optical properties of the film, and an electrochemical workstation was employed to evaluate the photogenerated cathodic protection performance of the film on 304 stainless steel. Results showed that the TiO2/Au(10)/CdS composite film had the best photogenerated cathodic protection effect on 304 stainless steel with the open circuit potential of -1.252 V (vs SCE), and the photogenerated current density of 2.697 mA/cm2, which was 14 times that of pure TiO2 (0.185 mA/cm2). Besides, TiO2 combined Au and CdS to form a Z-type heterojunction, and this Z-type charge transfer mechanism could change the migration path of photogenerated electrons and promote the separation of photogenerated electrons and holes, and hence the films could provide effective cathodic protection for 304 stainless steel.

Keywords

• 304 stainless steel|tio2 nanobelts|z-type heterojunction|tio2/au/cds composite films|photogenerated cathodic protection