3D nanothorn cluster-like Zn-Bi2S3 sensitized WO3/ZnO multijunction with electron-storage characteristic and adjustable energy band for improving sustained photoinduced cathodic protection application

Solar energy-driven photoinduced cathodic protection (PICP) technology utilizes solar energy to protect marine metallic structures against severe marine corrosion. To enhance the solar energy utilization and strengthen dark-state application for realizing long-term protection, herein, a 3D nanothorn cluster-like WO 3 /ZnO/Zn-Bi 2 S 3 multijunction with electron-storage characteristic and adjustable energy band was constructed. It exhibited an enhanced continuous release of photogenerated electron and sustained cathodic protection in dark conditions. Exposed to only 100 s of simulated sunlight irradiation, the WO 3 /ZnO/Zn-Bi 2 S 3 could store 5.27×10 −2 C electrons and provide up to 5460 s of sustained CP for the coupled metal after light stops, which was 10.8 and 3.5 times higher than those of WO 3 /ZnO (4.89×10 −3 C) and WO 3 /Zn-Bi 2 S 3 (1.51×10 −2 C), respectively. The WO 3 nanothorn cluster-like substrate with reversible valence transformation of W 6+ /W 5+ together with the large surface area and one-dimensional transmission path can store photogenerated electrons under illumination and release photogenerated electrons after light stops efficiently. Notably, the tri-phase heterojunction with introduction of intermediate “Carrier Springboard” ZnO between WO 3 and Zn-Bi 2 S 3 contributed to the building of well-matched energy band gradient to strengthen the directional backward transfer of photogenerated electrons and holes. The energy band of Bi 2 S 3 sensitizer was adjusted towards negative direction by doping with zinc element to boost PICP application performance. The reversible valence transformation of Bi 3+ /Bi 5+ could promote the consumption of photogenerated holes. These synergistically enhanced the sustained PICP performance of the WO 3 /ZnO/Zn-Bi 2 S 3 photoelectrode both in dark and light conditions. This design shed light on energy-storage photoelectrodes for long-term PICP of metallic materials.