The last decade has seen the emergence of a new research area towards environmentally-friendly antifouling coatings. Combined with non-toxic, corrosion-resistant properties and good chemical stability in saline conditions, the photocatalytic activity of TiO₂ make this oxide a good, eco-friendly antifouling alternative for marine environments. The photocatalytic properties of TiO₂ enable local generation of Reactive Oxygen Species (ROS) such as OH° or H₂O₂ that can directly or indirectly damage cells. But even if it is showing promising results in in vitro experiments, the limited exposure to sunlight in the sea and the restricted absorbance range of TiO₂ in the solar spectrum (UV) are important issues.

To enhance the antifouling properties of TiO₂, two strategies were followed : increasing the effective surface area by microstructuration and synthetising composite thin films including Cu. In this context, TiO₂ thin films have been synthesized using Aerosol Assisted Metal Organic Chemical Vapour Deposition (AA-MOCVD). After optimizing deposition parameters, nanometric petal assemblies, forming hierarchical microflower-like structures, are obtained on a TiO₂ thin film. The impact of these microflowers on various properties such as the effective surface area, the roughness and wettability is investigated by comparing flat TiO₂ thin films, with those covered with microflowers.

Secondly, Ti-Cu-O composite materials were synthesized by AA-MOCVD. This composite is expected to increase the photocatalytic activity through the TiO₂-Cu₂O heterojunction that can promote the electron-hole separation and slow down the charge recombination. The impact of the Cu precursor concentration and the annealing temperature on the thin film morphology and composition is investigated.

The photocatalytic properties of TiO₂ films and Ti-Cu-O composites are then investigated and the interaction between TiO₂ films and biological organisms is investigated at molecular and cellular scales. Protein adsorption is quantified by QCMd and the antifouling properties towards Vibrio harveyi are demonstrated using in vitro cultivation experiments.

Membres du jury/ Jury members :