Cost Effective Inkjet Printing of Titania Nanoparticles for Photocatalytic Applications

Titania is one of the most promising materials in the field of light induced catalysis on surfaces. In the last decades researchers investigated in particular applications like self-cleaning and photochemical degradation of pollutants. Moreover titania present antibacterial properties, which allows to consider uses in the biomedical field. The most immediate method to produce titania coatings is the anodization of a titanium substrate, which is able to provide good results in terms of quality and reproducibility. Alternative methods to employ titania when a titanium substrate cannot be provided have been developed as well, including TiO₂ codeposition with metals, sol-gel deposition and inkjet printing. In particular inkjet printing of titania nanoparticles is of great interest due to the possibility of creating patterns in an easy and cheap way, controlling the thickness of the deposited layer with good accuracy. TiO₂ inkjet printing has been attempted in the past mainly using laboratory printers, with good results in terms of photocatalytic and antimicrobial activity. Possible challenges for the future are the optimization of the method and the use of widely available office inkjet printers to increase the flexibility of the process.

The present work aims at depositing titania from a commercial office inkjet printer, modified to use custom made inks containing nanoparticles obtained by sol-gel synthesis. The nanoparticles of titania thus obtained are characterized via TEM to quantify the mean size and the diameters distribution. The subsequent formulation of the printing inks is done following the specifications of the corresponding pigmented inks used in standard printing on paper. In particular viscosity and surface tension are measured and modified to obtain the best printing quality. Finally the printed layers, either in form of continuous samples or patterns, are characterized from the morphological point of view and their photocatalytic efficiency is tested. Moreover, as preliminary results, the printed layers are tested on conductive substrates for electrophotocatalysis as well.