Preparation of multistage heterojunction composite film for round-the-clock photocathodic protection

A WO3/BiVO4/CdS-CdSe multistage heterojunction film with a well-matched energy band was constructed to solve the bottleneck problem of photocathodic protection technology not being able to work in round-the-clock continuous operation in practical applications. The WO3 nanoplate as optoelectronic storage was closely combined with the BiVO4, which demonstrated a faster electron transfer rate, to promote photoelectron separation and transfer. Meanwhile, sensitization of CdS-CdSe quantum dots could extend light absorption to the visible region. The photoelectrochemical experiment results showed that the potential of 304 stainless steel as the protected material was negatively shifted to −1.09 V (vs. Ag/AgCl), after coupling with WO3/BiVO4/CdS-CdSe in 3.5 wt% NaCl solution under simulated sunlight (AM 1.5 G). Notably, the lower potential in this system could also remain for 7 h without the sunlight to achieve round-the-clock photocathodic corrosion protection. [Display omitted] •WO3/BiVO4/CdS-CdSe with a unique multivariate heterojunction was prepared.•The homogeneous film promotes the separation and transfer of photogenerated carriers.•The corrosion potential of 304SS coupled with the as-prepared photoanode drop 910 mV.•Round-the-clock photocathodic protection for 304SS can be achieved.