Enhanced visible light photocatalytic activity of tin oxide nanoparticles synthesized by different microwave optimum conditions

A facile and rapid microwave irradiation method was used to synthesis of nanocrystalline tin oxide (SnO and SnO₂) powders with different microwave power (360, 600 and 900 W) and the effect of microwave power on the structural, surface morphology, optical and photocatalytic activity has been systematically investigated. Powder X-ray diffraction (PXRD) results suggest that the samples were tetragonal Romarchite and tetragonal rutile type structure of SnO and SnO₂ respectively. Transmission electron microscope (TEM) images illustrates that both SnO and SnO₂ consists of spherical shaped morphology with an average diameter of around 25–40 nm, which is in good agreement with the grain size calculated from XRD results. Raman, Photoluminescence and Energy dispersive spectra (EDS) analysis results indicate that the as-synthesized samples were oxygen deficient with the increase of microwave power up to 900 W. A considerable red-shift in the absorption edge and decreasing the band-gap (3.67–3.57 eV) of SnO₂ was observed with the increase of microwave power. The photocatalytic activity was monitored via the degradation of Methylene blue (MB) and Rhodamine B (RhB) dyes under visible light irradiation and SnO₂-900 W sample shows better photocatalytic activity than SnO-300 W and SnO₂-600 W. The possible photocatalytic mechanism was also discussed in detail.