Tuning Hopeite-Phase Dominant Phosphate Coating with Dy-Doped MoS2 for Improved Antibacterial Surface Protection

The susceptibility of steel toward biologically aggressive environments necessitates the need for engineering systems yielding antibacterial efficiency and biocorrosion resistance. This study presents design and fabrication of multifunctional phosphate coating matrix integrated with physiochemically tailored dysprosium-doped MoS2 (3% Dy-doped MoS2) nanoparticles for enhanced antibacterial and anticorrosion performance. The superior biocidal activity of tuned Dy-doped MoS2 arises from the contact-killing effect of hierarchical cauliflower nanostructures and ROS-induced stress enabled by the tuned band gap (1.65 eV) of 3% Dy-doped MoS2. The tailored nanoparticle integration into the phosphate bath influences the crystallization kinetics, resulting in the development of a dense hopeite (Zn2(PO4)2.4H2O)-rich layer in tuned 3% Dy-doped MoS2-based zinc phosphate composite (0.3DyM-ZPC) coating. The microstructurally tuned 0.3DyM-ZPC coating exhibits enhanced hydrophobicity (∼115°), limiting wettability, and microbial adhesion. The corrosion resistance performance was significantly enhanced, with the 0.3DyM-ZPC coating exhibiting lowest corrosion current density (326.7 µA/cm2) and corrosion rate (2.07 × 10-2 mmpy), owing to the improved barrier protection. The 0.3DyM-ZPC coating demonstrate substantial decrease in bacterial survivability (24.20, 21.62, and 17.79%) against different bacterial inoculums. Long duration bacterial immersion studies (28 days) revealed minimum biofilm formation and predominant dead bacterial cells on the tuned DyM-ZPC coating surface.