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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]

The global annual consumption of marine metal corrosion is a significant challenge to the service life of metals and the development of marine strategies. A tri-dimensional AgInS2/In2S3 co-modified TiO2 nanobush (NB) superstructure photoanode is constructed. It shows superior photoelectric cathodic protection (PECP) characteristic for pure copper whose self-corrosion potential is more negative in simulated natural marine environment without additional any hole scavengers under simulated solar light illumination. Origin from the more negative energy level potential of AgInS2/In2S3, the quasi-Fermi level of the photogenerated electrons of TiO2 NB/AgInS2/In2S3 was pull to a more negative position, reinforcing the transmission of photogenerated electrons to the pure copper whose self-corrosion potential is more negative. The sensitizer AgInS2 together with the assistant layer In2S3 dramatically enhances the PECP performance of TiO2 NB/AgInS2/In2S3. The tri-dimensional ultrafine branch-like architecture of TiO2 NB with the nanoparticles quickens the collection and transfer of photogenerated electrons to the metallic pure copper. This environmentally friendly 3D photoanode structure provides a good reference for the optimized construction of photoelectric materials for marine metal corrosion protection. The tri-dimensional AgInS2/In2S3 co-modified TiO2 nanobush superstructure photoanode possesses superior photoelectric cathodic protection characteristic for pure cooper whose self-corrosion potential is more negative in simulated marine environment under simulated solar light illumination. [ABSTRACT FROM AUTHOR]