Sunlight driven high photocatalytic activity of Sn doped N-TiO2 nanoparticles synthesized by a microwave assisted method

Environment-friendly photocatalysts under sunlight with wide spectral responses for wastewater treatment are currently an exciting area of research. Herein, we report the synthesis of Sn doped N-TiO2 nanoparticles with different contents of Sn by a greener microwave assisted method. The phase purity, morphology, particle size, optical properties, and elemental composition were systematically analyzed by various sophisticated analytical techniques. The X-ray diffraction (XRD) patterns revealed Sn doped N-TiO2 nanoparticles in the anatase phase. The shift of XRD peaks observed at lower angle and the XPS results indicate the successful doping of Sn4+ in the lattice of N-TiO2. The optical absorption edges of Sn-doped N-TiO2 showed an obvious red shift that plays a crucial role in the photocatalytic activity under abundant sunlight. We further explored Sn doped N-TiO2 for photodegradation of methyl orange (MO) and Zopiclone (Z-class drug) under sunlight irradiation. A maximum of 95% and 91% of MO and Zopiclone were photodegraded over 0.25% Sn doped N-TiO2 under sunlight within 80 and 120 min, respectively, which is ∼7-fold higher than bare N-TiO2. The enhanced photocatalytic activity could be attributed to combined effects of reduced crystallite size, suppressed recombination rate of photogenerated electron-hole pairs, and increased optical absorption towards visible light that establish their impending use to treat polluted water. The possible mechanism for high photocatalytic activity of Sn doped N-TiO2 has also been discussed.