Energy-Storable and Efficient Photogenerated BiVO ₄ /MoS ₂ /Bi ₂ S ₃ -Based Photocathodic Protection Coating toward Marine Corrosion Resistance

Metal corrosion in marine environments poses a formidable challenge. Photogenerated cathodic protection technology harnesses solar energy and semiconductor materials to generate photoelectrons for metal protection, offering broad application prospects. However, it currently suffers from limitations such as low photoelectric conversion efficiency, poor photoanode stability, and the inability to provide protection in the dark. Here, a BiVO₄/MoS₂/Bi₂S₃ composite was successfully synthesized and utilized to construct highly efficient photocathodic protection coatings. BiVO₄/MoS₂/Bi₂S₃ exhibited a band gap of 1.138 eV (a 2.5 eV band gap for BiVO₄), the lowest open-circuit potential of 0.53 V vs AgCl/Cl, and a maximum photocurrent density of 128 μA·cm^-2 (approximately 35 times that of pure BiVO₄) because the p-n heterojunction structure formed by the BiVO₄/MoS₂/Bi₂S₃ composite effectively reduces electron-hole recombination rates. Furthermore, the BiVO₄/MoS₂/Bi₂S₃ composite displayed outstanding energy storage properties, sustaining electron supply for hours after light exposure had ceased and enabling efficient photogenerated cathodic protection in dark environments. Notably, the epoxy composite coating incorporating 1 wt % BiVO₄/MoS₂/Bi₂S₃ (1% BiVO₄/MoS₂/Bi₂S₃/EP) demonstrated the superior corrosion resistance stability. After 40 days of immersion in a 3.5 wt % NaCl solution, the impedance modulus at 0.01 Hz (|Z|_0.01Hz) decreased by only 1 order of magnitude. This work provides an innovative strategy for addressing marine corrosion challenges by introducing an energy-storable BiVO₄/MoS₂/Bi₂S₃ composite into epoxy resin coatings.