Bifunctional WO3/CdZnS heterojunction photoelectrodes for efficient and sustainable anticorrosion and antifouling

Most conventional photoelectrode materials lack electron storage capability, limiting their function to photoelectrochemical cathodic protection (PECCP) only under illumination and rendering it ineffective in dark conditions. This significantly restricts the application of PECCP in the corrosion protection of metallic materials. In this study, WO 3 /CdZnS heterojunction photoelectrodes with electron storage functionality were synthesized via a two-step hydrothermal method, overcoming a key limitation of previously reported PECCP photoelectrodes that cannot store electrons. The saucer-like WO 3 nanoplates (exhibiting nanorod-like structures with lengths of ∼2 μm) feature a loose and porous surface that increases the number of active sites and provides additional channels for the storage of photogenerated electrons. Meanwhile, the CdZnS composite extends the light absorption threshold to 539 nm, compared to 471 nm for pure WO 3 , and supplies photogenerated electrons to WO 3 . Under AM1.5 G illumination in 3.5 wt% NaCl solution, the WO 3 -2/CdZnS photoelectrode exhibited a photoinduced potential of 436 mV and a current density of 25.7 μA cm⁻ 2 . After 100 s of light exposure, the WO 3 -2/CdZnS photoelectrode stored a charge of 1.19 × 10⁻ 3 C, sufficient to provide time-delayed cathodic protection to 316 L stainless steel (316 L SS) for 4826 s. Furthermore, the photoelectrode achieved a 99.2 % bactericidal efficiency against Pseudomonas aeruginosa (P. aeruginosa) within 60 min of illumination and maintained 55.2 % efficiency in the dark following pre-illumination, thereby effectively preventing biofouling. The preparation of these dual-functional storage-type anticorrosion and antifouling photoelectrodes offers new insights for the anticorrosion and antifouling protection of marine equipment.