Band structure regulation for improving the photoinduced cathodic protection performance of TiO2/ZnxIn2S3+x heterojunctions

The degree of band matching is crucial for the photoelectric conversion performance of heterojunctions. In this work, TiO 2 /Zn x In 2 S 3+x (TO/ZIS-X, X=1, 2, 3, 4) heterostructures and their electrochemical and photoelectrochemical tests were studied. According to the energy band analysis of a series of TO/ZIS-X, it is found that I-type heterojunction can be formed between TO and ZIS-1, while Z-type heterojunction would be formed between TO and ZIS-2, ZIS-3 and ZIS-4. The photoinduced potential drop associated with current density of TO/ZIS-2 in 3.5 wt% NaCl are 505.82 mV and 18.61 μA·cm −2 , respectively. This result is much higher than those of homogeneous TO and single-phase ZIS-X. The desirable photoelectrochemical cathodic protection performance of the photoelectrode is owing to the loading of Zn x In 2 S 3+x , which broadens the light absorption threshold and improves the electrochemical activity area. Besides, the construction of Z-type heterojunction retains the photogenerated electrons/holes with strong reduction/oxidation ability, which greatly promotes the photoelectrochemical cathodic protection capability on 316 L stainless steel.