Micromixing-assisted preparation of TiO2 films from ammonium hexafluorotitanate and urea by liquid phase deposition based on simulation of mixing process in T-shaped micromixer

Abstract

Abstract Preparation of well-ordered TiO2 films from alkaline solution by liquid phase deposition (LPD) method is still challenging owing to the fact that, in traditional mixing process, several disadvantages exist in controllable homogenous chemical reactions. In this contribution, mixing process in a porous dispersed double T-junction micromixer was designed and investigated using numerical simulation. It is obtained that high mixing intensity can be achieved by micromixer with inlet velocity of 0.6 m s−1 and microfiltration meshes 10 μm in size. A micromixing-assisted platform consisted of two syringe pumps and a micromixer was manufactured to efficiently fabricate TiO2 films via mixing of (NH4)2TiF6 and CO(NH2)2 as reactants and fluorine doped tin oxide, F: SnO2 (FTO), conducting glass substrates by LPD in alkaline solutions. The results suggest that surface morphology of TiO2 films fabricated by micromixing can be easily controlled in comparison with that of specimens prepared by traditional stirring mixing process. The dense and well-ordered TiO2 films derived from micromixing have enhanced adhesion strength, high hardness, good hydrophilic and excellent photoelectrochemical properties. Particularly, homogeneous reaction could be inhibited in micromixer and an ideal supersaturation solution would be formed via micromixing treatment, which significantly facilitates the formation of high quality TiO2 films by heterogeneous nucleation on substrate surface. These obtained achievements are expected to promote further application of TiO2 films in a variety of domains including photocatalysis and corrosion protection of metals.