WO₃/SrTiO₃ Heterojunction Composite: A Promising Photoanode for Photochemical Cathodic Protection

Introducing second-phase materials to construct heterojunctions can effectively improve the photoelectrochemical performance of semiconductor materials. In this study, tungsten trioxide/strontium titanate (WO₃/SrTiO₃) composites are designed and prepared to protect 304 stainless steel (304 SS) via photochemical cathodic protection (PCP) technology in a simulated sunlight environment. The results demonstrate that the photoelectric properties of composites containing WO₃ with different mass fractions and SrTiO₃ vary, and the composites show enhanced PCP performance. Coupling 304 SS with the WO₃/SrTiO₃ composites containing 20 wt % of WO₃ shifts the potential of the 304 SS from –0.13 to –0.34 V, and the composites generate 4.5 times more photocurrent density than SrTiO₃ alone. Heterojunction electric fields formed on the interface of WO₃/SrTiO₃ enhance the separation efficiency of photogenerated electrons and holes, promoting PCP performance.