A low-temperature method was used to prepare and inkjet-print photoactive TiO2 films on polymeric substrates using a commercial inkjet printer. The as-prepared substrates were used in a microfluidic device fabricated with selective transmission laser welding. The catalytic activity of the printed nanolayers was studied in a microreactor based on the photodegradation of methylene blue as a standard pollutant. The overall process is cost-effective and efficient in manufacturing flexible lightweight microreactors coated with tunable catalytic films for catalysis and photocatalysis applications.
Many attempts have been made to immobilize photocatalytic particles in continuous reactor systems such as using optofluidic devices or coated microchannels manufactured on ceramics, glass or silicon. In spite of the progress on material deposition techniques into macro and microfluidic devices, there are still limitations due to complex fabrication procedures and low performance. Among different coating techniques, material printing or inkjet printing has emerged recently. This novel technique is suitable for non-contact uniform coating of functional metal oxides such as TiO2.
In this work, the TiO2 sol was prepared from hydrolysis of TiCl4 at 100 "?" and directly dispersed in ethylene glycol for ink formulation. The ink printability and colloidal stability were assessed by rheological and interfacial properties. X-ray diffraction spectrum of the synthesized TiO2 confirmed the crystallized phase of pure anatase with an average particle size of 4.2 nm. The synthesized TiO2 exhibited higher activity (k = 0.021 min-1) compared to the commercial standard powder (k = 0.011 min-1). Furthermore, the microreactor showed promising performance and stability, and the inkjet printing method proved to be a customizable technique for coating active nanocatalysts.