Novel self-cleaning coating that meet the world’s new hygiene standard

Antifouling paints are commonly used to maintain the performance and durability of ships. For decades, antifouling paints have mainly adopted copper or zinc as a major biocide to reduce marine organism adhesion, yet, it is highly toxic to marine ecosystems and foodchain. Our recent measurements show that the concentration of heavy metal in the sediment exceeds the international permissible limit by 60 times. With this in mind, Nano-MAP is designed to fully replace heavy metal-based antifouling paints.

Nano-MAP is 100% safe to use and does not adversely affect the marine ecosystem. The superior performance of the Nano-MAP can save fuel by 30-40% and reduce maintenance workload significantly. With the presence of Nano-MAP, any biofoulant attached can be easily removed with gentle brushing. The payback period is typically one year or shorter.

Nano-MAP contains anion-doped semiconductor metal oxide. Upon activation by the solar radiation in seawater, Nano-MAP induces photocatalytic oxidation and superhydrophobicity. These effects can deter unwanted growth of barnacles, tubeworms and mussels on the hull. In addition, the nanomaterials are modified by co-doping to achieve solar photocathodic effect. As a result, a single protective coating possesses bifunctional properties for antifouling and anticorrosion protection.

Hull fouling increases frictional resistance, result in additional weight and poor fuel efficiency. The excellent performance of Nano-MAP can save cost in fuel consumption and subsequent maintenance. You don't need to reapply the Nano-MAP coating every year.

Nano-MAP contains carbon co-doped Titania and composite. We take into account the intensity of solar radiation in seawater, to produce photocatalytic oxidation and super hydrophobicity to perform anti-fouling and anti-corrosion onto the ship hull.

Hard fouling organisms include barnacles, encrusting bryozoans, mollusks, polychaete and other tube worms, and zebra mussels. Examples of soft fouling organisms are seaweed, hydroids, algae and biofilm "slime".

Since the photocatalyst catalyzes the generation of reactive oxide species for disinfection, it won't be exhausted. The anti-fouling effect can last much longer to 1 year and even longer. The biofoulant layer can be easily removed by soft brushing.

Nano-MAP can effectively perform anticorrosion by photocathodic protection. Upon the formation of electron-hole pairs, the electrons can be transferred to the metal substrate and thus decrease the electrode potential, resulting in anticorrosion effect. Another anticorrosion mechanism is that the nanostructured material can act as a filler to impede the transport of Cl- and Na+ ions for corrosion resistance.

Sunlight can penetrate through seawater up to a depth of 200m. At a few meters below the seawater surface, 40-70% solar radiation is still available. Therefore, solar photocatalysis for marine antifouling makes sense. Immobilized photocatalyst performs antifouling effect on the hull surface and does not release any chemicals into the seawater. Therefore, it is safe with many other potential applications in the marine industries.

In principle, when a photocatalyst, such as titanium dioxide (TiO2), is irradiated by activating light with the presence of water, strong oxidizing hydroxyl radical can be produced. Such photocatalytic oxidation has various functional uses. Nano-MAP contains anion doped TiO2 for enhanced solar photocatalysis. We further modified the material by anion/metal co-doping to enhance the antifouling effect with additional anticorrosion function.