Microemulsion-based synthesis of a visible-light-responsive Si-doped TiO2 photocatalyst and its photodegradation efficiency potential

Highlights: • Si-doped TiO₂ nanoparticles synthesized with a microemulsion route. • There was a relation with the size of nanoparticles and synthesis parameters. • The photocatalytic activity improved by decreasing the water amount in the system. • The highest activity depended on molar ratio of water-to-AOT and calcination. • Doping of silicon ions in TiO₂ lattice could shift its optical absorption in visible ranges. In this research, a facile microemulsion route was applied in the synthesis of a series of Si-doped TiO₂ nanoparticles with uniform shape, narrow size distribution and high photocatalytic activity. The size and structure of the resulting crystals were evaluated by XRD and TEM techniques, respectively. The size of nanoparticles increased with the increment of water and calcination temperature. The photocatalytic activity of the nanoparticles was improved by decreasing the water amount in the system. In improving the crystallinity, the calcination led to the formation of quartz and anatase form of TiO₂. Moreover, it was shown that the highest catalytic activity strongly depends on both the molar ratio of water-to-AOT and calcination temperature. The temperature increase resulted in the increment of crystallinity, light adsorption, and particle size. The UV–visible diffused reflectance analysis proved that the doping of the silicon ions in the TiO₂ lattice can shift its optical absorption in the visible range. The size of the spherical nanoparticles was around 10–20 nm. Hence, Si-doped TiO₂ prepared by ME method yields excellent and uniform features resulting in better performance for future applications.