Investigations into the physical properties of SnO2/MoO3 and SnO2/WO3 bi-layered structures along with photocatalytic and antibacterial applications

This work covers the surface defects effect of SnO2/MoO3 and SnO2/WO3 structures on photocatalysis. One micrometer thick SnO2 bottom layers with porous microstructure and 0.1 thick micrometers of MoO3 or WO3 top layers were consecutively deposited onto glass substrates using the thermal evaporation technique. First, these bi-layered structures were characterized by X-ray diffraction, Raman spectroscopy and atomic force microscopy in order to identify both their structures and their morphological properties. Second, both UV-vis-NIR spectrophotometer measurements and ellipsometry spectroscopic proved that the band gap decreased from SnO2 to coupled SnO2/MoO3 and SnO2/WO3. In addition, a comparison of the photocatalytic degradation of methylene blue (MB) was done under UV-visible light irradiation. The results showed that these structures exhibit promising candidates to degrade methylene blue (MB). Based on the characterization, it was found that SnO2/MoO3 and SnO2/WO3 structure showed higher photocatalytic activity than that of SnO2. This relatively high photocatalytic activity may be attributed to the charge transfer between those bi-layered oxides. Finally, the antibacterial activity test towards Pseudomonas Aeroginosa showed that only SnO2/WO3 thin film has exhibited antibacterial effect.