Preparation of Titania Photocatalyst Inks for Inkjet Printing onto Indium Tin Oxide Substrate

Abstract

Researchers have been taking great interest in titania (TiO₂) due to its potential in many applications, such as self-cleaning and antifogging surfaces. Two common forms of TiO₂ that have been widely used are nanopowdered-form and TiO₂ thin film supported on substrate. Among these two, TiO₂ supported thin films reduce the requirement for any further post-treatment filtering of the decontaminated fluid, although the surface area is more limited compared to the nanopowdered-form. Many methods can be used to prepare TiO₂ thin films onto substrates, such as sputtering technique, sol-gel method, electrochemical process, chemical vapour deposition (CVD) and spray pyrolysis. However, the methods mentioned above involve multiple steps, require long processing time, the usage of high temperature is necessary and many more. One way to solve these problems would be by using the inkjet printing method, which is an economical and cost-effective technique used for the deposition of thin layers on a substrate that provide selective and precise deposition of materials with a low waste of materials. In this work, stable TiO₂ photocatalyst precursor inks were prepared with different concentrations for inkjet printing method. The prepared TiO₂ photocatalyst precursor inks were then converted to the powdered form in order to determine the physicochemical properties. The field emission scanning electron microscopy (FESEM) images showed the TiO₂ particles were almost spherical in shape, with concentration of 0.15 M showing the most uniform size and the least agglomeration. Energy dispersive X-ray spectroscopy (EDX) results confirmed the presence of Ti and O elements in all of the samples, proving the successful synthesis of TiO₂. X-ray diffraction (XRD) patterns confirmed the synthesized TiO₂ samples are in the anatase phase. Results from diffuse-reflectance ultraviolet-visible spectroscopy (DR-UV-Vis) showed that the band gap energy of all samples was in the range of 3.42 and 3.46 eV, higher than the theoretical value, which might have been caused by the indirect transition of the synthesized TiO₂.