Titanium-based photocatalytic coatings for bacterial disinfection: The shift from suspended powders to catalytic interfaces

International audienceAccessibility to a clean indoor environment is still an important problem in the world. Photocatalysis based on semiconductor materials was proposed as a green solution for contaminated surfaces and domestic areas. This treatment has been considered by many researchers using diverse preparation methods. Titanium dioxide (TiO2) was extensively investigated to treat dyes and microorganisms in wastewater, indoor air and even in wild environments. TiO2 showed divergent efficacy against Gram+ and Gram- bacteria, viruses (DNA-viruses, RNA-viruses, and/or reverse transcribing viruses), algae (unicellular, microalgae horizontexpressionl ellipsis ) and free-floating genomic DNA. Today, photocatalysis mediating TiO2 for pollutants removal in real settings is attracting a lot of attention. TiO2 absorbs in the UV spectral region and many techniques were adopted to red shift its absorption to the visible region such as doping, coupling with other semi-conductors or decorating it with plasmonic materials. TiO2 uses started as suspended material in aqueous media. This suspension was fast faced by the difficulty to recover the catalyst after treating water. In the present review, we present the shift from the photocatalytic activity of Ti-based catalysts/photocatalysts for the disinfection of polluted water (TiO2 in suspension) to the implementation of smart indoor surfaces (supported TiO2) presenting self-sterilizing properties. In this review, we present the general context of the water issue as raised by the United Nations 2030-agenda, we show an overview of photocatalytic materials and we try to link the reported photocatalytic mechanisms for the disinfection process. At the end of this review, we stress the advantages of using supported photocatalytic thin films and the interfacial phenomena leading to bacterial killing without sacrificing the catalyst that can be easily reused