TiO₂ Nanoparticle/Carboxymethyl Cellulose Coatings for Photocatalytic Dye Degradation in Simulated Seawater

In this work, by integrating TiO2 nanoparticles and sodium carboxymethyl cellulose (CMC) binder, a green bifunctional TiO2 nanostructured coating (T-SCMC-vac.) directly coupled with 304SS was designed under vacuum thermal treatment, aiming to achieve methyl orange degradation and metal anticorrosion. The T-SCMC-vac. nanostructured coating exhibited a reaction constant 1.7 times higher for degrading methyl orange compared with its counterpart in the simulated seawater environment, demonstrating good photocatalytic performance. Simultaneously, T-SCMC-vac. provided effective photocathodic protection to 304SS. The open circuit potential negatively shifted to −500 mV (vs Ag/AgCl), and the photoresponse current and corrosion current densities reached approximately 10 μA cm–2. Furthermore, the nanostructured coating showed good stability, as evidenced by 98% retention in photocatalytic capability after five cycles and by 14 h long-term photocathodic protection. The experimental results and theoretical calculations suggest that the enhanced performance can be attributed to the chemical interaction between TiO2 nanoparticles and CMC via C–O–Ti bonds, which significantly facilitated photogenerated carrier transport and aligned the potential positions of TiO2, reactive oxygen species, and 304SS. Our findings provide a facile strategy for designing green bifunctional TiO2 nanostructured coatings on ocean-based facilities with seawater pollutant degradation and metal anticorrosion properties.