Coatings

Developing efficient heterojunction photocatalysts is essential to address the challenge of degrading persistent organic pollutants. In this study, a multi-scale characterization strategy was employed to investigate the implications of interfacial connectivity between synthesized graphitic carbon nitride (g-C₃N₄) /bismuth oxychloride (BiOCl)e removal of Rhodamine B (RhB) and Methyl Orange (MO). Morpho-structural characterizations, including Scanning/Transmission Electron Microscopy (SEM/TEM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and N₂ physisorption (Brunauer–Emmett–Teller (BET)) analyses, confirmed the successful construction of an intimate interfacial contact between g-C₃N₄ and BiOCl. The optimized composite (15% g-C₃N₄/BiOCl), prepared via a one-step hydrothermal method, exhibited enhanced photocatalytic performance following pseudo-first-order kinetics described by the Langmuir–Hinshelwood model, with apparent rate constants of 0.166 min⁻¹ for MO and 0.519 min⁻¹ for RhB. Under visible-light irradiation, degradation efficiencies of 98% for MO (120 min) and 99% for RhB (35 min) were achieved, outperforming the pristine components. Complementary optical and electrochemical analyses indicate improved light absorption and charge-separation efficiency in the heterojunction system. In addition, the photocatalyst demonstrated good operational stability over four consecutive cycles, maintaining 91.70% activity for MO and 99.76% for RhB. Overall, this work highlights the synergistic photocatalytic g-C₃N₄/BiOCl heterojunction and provides a valuable insight to guide the design of advanced materials for pollutant remediation.

This Special Issue, “Surface Engineering, Coatings, and Tribology”, was open for submissions from the entire community and incorporates a selection of studies presented at the VIII National Symposium and First Latin American Meeting on Surface Engineering and Tribology [...]

In the marine environment, numerous factors endanger the preservation of underwater rock surfaces as well as submerged archeological artifacts, including physical, chemical, and biological processes. Limestone and marble are common materials used in artifacts due to their availability and long-term durability. However, such surfaces provide a suitable substrate for the settlement of micro- and macro-organisms, causing so-called biofouling, which significantly contributes to stone deterioration. Previous studies have demonstrated the applicability of antifouling coatings containing ionic liquids (ILs) on marble surfaces and assessed their durability for up to 15 days under submerged environments. To further corroborate these results, additional physical studies (colorimetric, contact angles, capillarity water absorption measurements, and UV aging) were carried out on treated limestone. Washout tests were also performed on both lithotypes to verify the coatings’ stability under medium-term underwater exposures. The results of these investigations are reported here. Our data confirm that the application of IL-based coatings had no effect on the intrinsic properties of the limestone surfaces, as previously reported for marble, including resistance to daily UV irradiation. In addition, laboratory tests demonstrated good coating durability against seawater erosive action for up to 6 months.