Thermally Stable Ceramic-Based Nanocomposite Coatings for Versatile and Reusable Air Filtration Media

Reusable air filtration systems are increasingly explored as sustainable solutions for indoor air quality control, provided that effective sterilization and long-term antimicrobial performance can be guaranteed. This study investigates thin ceramic-based nanocomposite coatings applied to conventional air filter media to enable dry-heat sterilization and repeated reuse. Silver nanoclusters embedded in silica (SiO2) or zirconia (ZrO2) matrices were deposited by radio-frequency co-sputtering onto metallic, glass-fiber, and polymeric substrates. Thermally stable ceramic oxides were selected to preserve coating integrity, regulate silver ion release, and maintain the original filter porosity. Morphological and structural characterization (FESEM, TEM, UV–Vis, XRD) revealed porous amorphous SiO2-based coatings and denser ZrO2-based coatings, both featuring a uniform distribution of silver nanoclusters. Antibacterial and antifungal activity against Staphylococcus epidermidis, Escherichia coli, and Candida albicans was confirmed through inhibition halo tests, CFU quantification, and aerosol contamination experiments. A key outcome is the demonstrated thermalregenerability of the coated filters, which retained antimicrobial efficacy after multiple dry-heatsterilization cycles at 200◦C. While silica-based coatings exhibited higher silver ion release, zirconia-based coatings provided improved release control and structuralstability. These results highlight ceramic-based nanocomposite coatings as a promising approach for durable, regenerable, and scalable antimicrobial air filtration systems