Scalable InkJet-Based Additive Fabrication of Photocatalytic TiO2 Thin Films

Photocatalysts for water purification and energy production belong to the class of materials for which there is an urgent need for more environmentally friendly manufacturing. Here we report a high throughput method for inkjet printing of nano-structured photocatalytically active TiO2 films and a detailed analysis of their properties and photocatalytic performance. We show that the inkjet dispersion of TiO2 particles is highly reproducible which leads to a close to linear relation between the number of printed single layers and the thickness of the films. The films here obtained have uniform surfaces and the interfaces with the substrates are free from defects such as grain boundaries, ripples, or discontinuities. This contrasts with films obtained with the traditional doctor blade method. The inkjet printed films have higher photocatalytic performance than the doctor blade films which results in higher catalytic activity per mass of material used. Lifetime tests with wet and dry cycles show that the inkjet films subjected to 10 photocatalytic cycles of 100 minutes each have a loss of performance of only 7%, while the films made via the doctor blade method have a performance loss of 66%. These tests revealed additionally that the mechanical stability of the inkjet films is higher than that of the films manufactured via the traditional casting method. This set of results shows that inkjet printing can be an efficient method for the large-scale production of TiO2 photocatalysts.