Fabrication and Photocathodic Protection Performance of Bi2S3/CdS/TiO2 Nanocomposites for 304 Stainless Steel
TiO2 nanotube arrays are decorated with CdS and Bi2S3 by an ultrasonic-assisted succes-sive ionic layer adsorption and reaction(SILAR)method aiming to enhance thephotoelectric conversion ability of TiO2 and correspondingly the photogenerated cathodic protection performance for 304 stainless steel.The morphology,structural,element type and valence state of the TiO2 nanocomposites are charac-terized by SEM,XRD and XPS,the photoelectrochemical performance of nanocomposites is studied sys-tematically under irradiation of a simulated sunlight.The results indicate that the TiO2 nanocomposites decorated with proper amount of CdS and Bi2S3 by an optimal procedure exhibit the best performance,namely,the band gap is reduced to 2.4 eV,the light absorption range extends to the visible region,and the recombination rate of charge photogenerated carriers is greatly reduced.The electrochemical test re-sults show that Bi2S3/CdS/TiO2 nanocomposites have the lowest charge transfer resistance and the fast-est electron transfer rate,and the photocurrent density is enhanced to 850 μA·cm-2 under the condition of turning on light,which is 11.8％higher than that of CdS/TiO2 nanocomposites and 3.4 times that of TiO2 nanotube arrays.After coupling the nanocomposite with 304 stainless steel,the potential can be reduced to-0.99 V under simulated sunlight,which is about 70 mV lower than that with the undecorated TiO2 nanocomposites,and it can further enhance the photogenerated cathodic protection effect on 304 stain-less steel.
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