3D network-like SnIn4S8/TiO2 for photoelectric electron storage and sustained cathodic protection applications in both light and dark conditions based on nanoarchitectonics.

Severe marine metallic corrosion urges extensive research on corrosion protection methods. Environment-friendly photoelectric cathodic protection (PCP) technology for marine metallic corrosion adopting abundant solar light in ocean was developed speedily. Particularly, photoelectric materials with dark-state sustained cathodic protection performance are worthy of further studies in pursue of the long-term PCP. Based on nanoarchitectonics strategy, together with the integration of electron storage materials, herein, an environment-friendly network-like SnIn₄S₈/TiO₂ photoelectrode with electron storage capability was constructed. The flower-like SnIn₄S₈ with variable valence indium was compounded in situ on the ultrafine branched TiO₂ substrate and formed a dual network-like SnIn₄S₈/TiO₂ architecture. Its larger electrochemical surface area and electric double layer capacitance, and the reversible valence variation of In³⁺/In⁺, gives full play of the storage and release of photogenerated electrons. SnIn₄S₈-15h/TiO₂ photoelectrode offered photogenerated electrons to the coupled pure copper (Cu) electrode with electric quantity of 3401 µC under the simulated sunlight irradiation of 50 s, and sustainedly offered the stored photogenerated electrons to it with 1390 µC in the dark. Contrastively, single TiO₂ or SnIn₄S₈ did not show sustained PCP performance. The multiple architecture characteristics make SnIn₄S₈-15h/TiO₂ show enhanced PCP and sustained cathodic protection performance for Cu and 316 L stainless steel (SS) both under light illumination and in the dark. Polysulfide SnIn₄S₈ pulls the potential toward negative direction which benefits the PCP for more kinds of metals in 3.5 wt% NaCl solution (a simulated marine environment) without hole scavenger added. This work provides insights in the solar light-driven sustained PCP application. [ABSTRACT FROM AUTHOR]