Eco-friendly mangrove-derived nanocomposite coating for sustainable biofouling and corrosion protection in Persian Gulf field trials

: Marine biofouling and corrosion impose major environmental and operational costs on maritime industries. This study aims to develop an eco-friendly, mangrove-derived nanocomposite coating that sustainably mitigates both challenges. Aluminum oxide and titanium dioxide nanoparticles were green-synthesized using Avicennia marina leaf extract and integrated with multi-walled carbon nanotubes (MWCNTs) into a polydimethylsiloxane (PDMS) matrix. Structural characterization (XRD, FTIR, FESEM-EDS, UV-Vis) confirmed uniform nanoparticle dispersion and hybrid formation with enhanced photocatalytic efficiency. The optimized 0.5 wt% Al₂O₃-TiO₂@MWCNT/PDMS coating exhibited superior antibacterial performance, achieving 96.5 % inhibition against S. aureus, 97.2 % against E. coli, and 95.8 % against P. aeruginosa, alongside 98.7 % anti-algal suppression of Nannochloropsis oculata. Corrosion current density reached as low as 0.008 μA/cm2, while polarization resistance increased to 4750 kΩ·cm2. Four-month field trials in the Persian Gulf demonstrated a 68 % reduction in fouling coverage relative to control PDMS panels. Through green synthesis and the exclusion of toxic biocides, this coating minimizes ecological risk and supports UN Sustainable Development Goals 9 and 14 by providing a scalable, durable, low-impact solution for marine infrastructure protection.