Enhancing photocathodic protection of Q235 carbon steel by co-sensitizing TiO2 nanotubes with CdIn2S4 nanogranules and WO3 nanoplates

In order to improve the photocathodic protection (PCP) performance of TiO 2 and its continuous protection ability in the dark, we designed and prepared CdIn 2 S 4 /WO 3 /TiO 2 (C/W/T) photoanodes through sequentially depositing WO 3 nanoplates (NPs) and CdIn 2 S 4 nanogranules (NGs) on TiO 2 nanotubes (NTs) by simple hydrothermal method . The effect of hydrothermal time on the PCP performances of C/W/T for Q235 carbon steel (CS) was studied. The PCP performance of C/W/T was compared with that of pure TiO 2 , CdIn 2 S 4 /TiO 2 (C/T) and WO 3 /TiO 2 (W/T). When the hydrothermal time for preparing WO 3 NP S and CdIn 2 S 4 NGs was both 6 h, the prepared C/W/T possessed the optimal PCP performance. The photogenerated potential drop of C/W/T could reach 490 mV vs. SCE. The C/W/T exhibited higher photocurrent density (633 μA·cm −2 ) and lower charge transfer resistance (11.34 Ω·cm 2 ) than bare TiO 2 , C/T and W/T. The electron storage capacity of C/W/T was 2.88 times that of C/T, which may be attributed to the electronic storage properties of WO 3 NPs. In addition, C/W/T can provide continuous protection for Q235 CS for up to 10 h in the dark. This work provides a new idea for designing energy storage photoanode materials with good PCP properties. • The optimal hydrothermal time of preparing WO 3 NPs and CdIn 2 S 4 NGs was both 6 h. • C/W/T showed better PCP for Q235 CS than C/T, W/T, and TiO 2 . • C/W/T had higher electron storage and continuous protection capacity than C/T. • DFT calculations proved the formation of an intrinsic electric field in the C/W/T.