| Summary: | High efficient and large surface area of titanium doped tin dioxide (SnO<sub>2</sub>) based photocatalysts with various titanium doping contents varying from 0 to 4 mol% have been successfully prepared via a facile, low cost and eco-friendly co-precipitation method. Structural, morphological, textural, microstructural and optical properties of the prepared Ti-SnO<sub>2</sub> nanoparticles (NPs) have been investigated by X-ray diffraction (XRD), scanning electron microscope (SEM), the Brunauer–Emmett-Teller (BET) method, Raman spectroscopy, Fourier transform infrared (FTIR), UV-Vis spectroscopy and photoluminescence (PL) spectroscopy. It was found that both undoped and Ti doped SnO<sub>2</sub> NPs were crystallized in tetragonal structure and the crystallite sizes have been reduced from 19.9 nm for undoped SnO<sub>2</sub> NPs to 13.1 nm for SnO<sub>2</sub>: Ti 4%. As compared to pure SnO<sub>2</sub>, a decrease in size and a uniform distribution of spherical aggregates for 4% Ti doped SnO<sub>2</sub> sample have been noticed. Nitrogen (N<sub>2</sub>) adsorption-desorption isotherms of all synthesized NPs indicate that each nanopowder showed a IV type- isotherm with a hysteresis loop resulted in a typical porous materials containing macropores and mesopores. The raman spectra was marked with the appearance of three well resolved peaks including one intense peak centered at 633 cm<sup>−1</sup> and two other peaks at about 475 cm<sup>−1</sup> and 772 cm<sup>−1</sup> which might be ascribed to the characteristic modes of of the SnO<sub>2</sub> rutile-type. FTIR spectra of Ti doped SnO<sub>2</sub> NPs show a broad band situated in the region from 630 cm<sup>−1</sup> to 625 cm<sup>−1</sup> for all Ti–SnO<sub>2</sub> samples which could be assigned to the stretching vibrations of Sn–O–Sn. Optical studies revealed that the absorption edge of SnO<sub>2</sub>: Ti NPs showed a redshift with rising titanium concentration. This redshift resulted in a decrease in the optical band gap from 3.31 eV for pure SnO<sub>2</sub> to 2.87 eV for 4% Ti doped SnO<sub>2</sub> nanoparticles respectively. Rhodamine B dye (RhB) has been adopted to study the photocatalytic degradation of all synthesized Ti–SnO<sub>2</sub> NPs. Pure SnO<sub>2</sub> NPs has an intrinsic large band gap and it was sensitive to UV light. Thus, pure SnO<sub>2</sub> NPs display higher UV photocatalytic performance for decomposing the RhB. Titanium incorporation into SnO<sub>2</sub> has widely improved its photocatalytic performance towards RhB photodegradation under UV and Visible light irradiations. Precisely, the 4% Ti–SnO<sub>2</sub> based photocatalyst display the highest photacatalytic activity and can degrade both of 95% and 52% of RhB dye within 120 min respectively under UV and visible light irradiations. The enhanced photocatalytic activity of the 4% doped SnO<sub>2</sub> photocatalyst was further proved with the minimum PL intensity. The homogeneous incorporation of low Ti contents into the SnO<sub>2</sub> matrix allow to a significant reduce in the band gap leading to an efficient separation of photogenerated electron-hole pairs and consequently improves the absorption capability in the visible light.
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