Unleashing the antibiofouling potential of nano-structured ZrN-Cu coating through electricity

Abstract

The world needs more environmentally friendly materials every time, especially when the application demands constant interaction with fragile habitats. The naval industry is a crucial player in a globalised economy, and the ambient impact of ships on the seas is well-known. Biofouling is one of the significant issues in this industry, and paints with biocides are used as the principal coating solution. However, those are mechanically poor, releasing heavy pollutants into the oceans. Multifunctional coatings obtained by PVD technology could help overcome this situation. The present study proposes a solution to create an advanced coating composed of zirconium nitride and copper in a specific nano-architecture. The developed coating was obtained in a hybrid magnetron co-sputtering system, employing high-power impulse and direct current power sources in a reactive atmosphere. SEM and TEM expose the morphology and the structure of the coatings. EDX, RBS, and XPS were used to assess the chemical insights of the coating. Halo and biofilm tests (with Cobetia marina) were employed to evaluate the antibiofouling action of the coating. The results showed that the activation of the coating, regardless of the used method, provoked the copper migration to the surface, being crucial to obtaining the antibacterial action (reduced bacteria adhesion and > 3 log reduction in CFU on the surface) without affecting the coating integrity (assessed by SEM), and not releasing heavy metals in a significant manner (< 2 log reduction CFU on supernatant). This opens the option of this kind of material, which is environmentally friendly, to be applied in real applications.