Background: The photocatalytic activity of SnO2-TiO2nanocomposites was successfully
synthesized by Sol-Gel method, deposited on porous silicon material and annealed at 400, 600 and
800oC temperatures, with surface grain size in the range between 5 and 12nm. The photocatalyst
was characterized by X-ray diffraction (XRD), high resolution scanning electron microscopy (SEM),
thermogravimetry analysis (TGA), derivative thermogravimetry (DTG) and mass spectroscopy (MS).
The photocatalytic effect investigation suggests that this SnO2-TiO2photocatalyst presents important
photocatalytic efficiency to the methyl blue at a lower annealing temperature.
Methods: In this work, sol-gel method is used to prepare SnO2-TiO2 nanocomposites; which will be
deposited on porous silicon, annealed at different temperatures and investigated to understand their
structural, morphological, optical and physical properties. Its photocatalytic activity was evaluated
by using the degradation of the methyl blue (MB) under irradiation with UV light.
Results: The intensity of the characteristic absorption band of methyl blue at 655 nm decreased significantly
with the increasing irradiation time. Meanwhile, a change in color of the solution occurred;
turning from blue to colorless after 20 min of irradiation, and thus indicating the gradual decomposition
of methyl blue molecules during UV light irradiation in the presence of the prepared SnO2-TiO2.
As expected, no degradation of the SnO2-TiO2nanocomposites occurred under our experimental conditions.
The MB degradation efficiency was reported by C/C0 quantity; where C and C0 correspond
respectively to its concentration at time t and initial concentration. In the presence of photocatalysts,
it can be clearly deduced that after irradiation for 20 min, the C/C0 of the MB value was about 0%
with the prepared and untreated nanocomposites of SnO2-TiO2 and remains constant when using a
SnO2-TiO2nanocomposites treated at 800°C.
Conclusion: This research has successfully synthesized the SnO2-TiO2nanocomposites photocatalysts
by Sol-Gel process and deposited by spin–coating technique on porous silicon substrates. Besides,
all its structural, optical and catalytic properties were studied and related between them. The
obtained material was annealed at three different temperatures 400oC, 600oC and 800oC. It is denoted
that its grain size increases from about 5 nm to 12 nm with the annealing temperature. The photocatalytic
effect has been tested on the methylene blue solution which demonstrates that the nanometric
grain size enhances the adsorption properties and achieves a good photocatalytic performance at a