A comparative study of preparation methods of nanoporous TiO₂films for microfluidic photocatalysis

This paper presents a comparative study of three methods for preparing integrated nanoporous TiO2films for microfluidic based photocatalytic reactors. These porous films have inherent merit of large surface-to-volume ratio and should significantly improve the device photoreactivity. It is also expected that nanoporous thin films have different performance in microfluidic chambers from that in an open environment. Experimentally, films produced by water-based P25 TiO2colloids and alcohol-based P25 TiO2colloids as well as tetrabutyl titanate sol-gel have been implemented into both microfluidic chambers and bulk containers for a close comparison using photocatalytic induced degradation of methylene blue model chemical. The results show that although the water-based P25 method produces TiO2films with lower performance than the alcohol-based P25 method in the bulk container, it achieves the highest reaction rate in the microreactor (1.4% s-1, 17% higher than the alcohol-based P25 method and seven times higher than the TBT synthesis method). Such comparison suggests that the water-based P25 method may be a good choice for the microreactor.