TiO2 has materialized as an excellent heterogeneous photocatalyst for environmental and energy fields, including air and water splitting. It has 3.2 eV band gap with the absorption edge at near‐UV light. Tuning of the band gap of TiO2 into visible region is achieved by the doping of nitrogen. The optimum compositions of N doped TiO2 NPs are prepared by sol‐gel method at room temperature. The structural phase formation of materials is analyzed by XRD studies, which shows anatase phase. The crystallite size is calculated from XRD data, which is in nanometer range. FTIR spectra are studied to confirm the O‐Ti‐O, O‐Ti‐N bonding in N‐doped TiO2 and formation of ‐OH groups on the surface, which can extensively affect the TiO2 band structure and surface of catalyst. The morphology of samples is investigated by FESEM and HR‐TEM. The compositional stoichiometry is confirmed by EDAX analysis. An optical study is confirmed by UV‐Visible spectrophotometer.

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The Mn‐doped TiO2 nanoparticle photocatalysts have been prepared by a simple sol–gel method. 1, 3, and 5 mol% Mn‐doped TiO2 nanoparticles have been prepared by using a stoichiometric amount of manganese acetate and titanium isopropoxide as precursors of Mn and Ti respectively. The physico‐chemical characterization of the prepared samples has been studied by x‐ray diffraction (XRD), Brunauer–Emmett–Teller surface area analysis, field emission scanning electron microscope, energy dispersive x‐ray analysis, high‐resolution transmission electron microscopy, x‐ray photoelectron spectroscopy, Ultraviolet–visible spectroscopy, photoluminescence spectroscopy, Fourier transform infrared spectroscopy (FTIR) and thermogravimetric analysis (TGA). XRD study reveals the formation of pure anatase phase of TiO2 and decrease in crystalline size of TiO2 on increasing the Mn doping content. TGA reveals minimum weight loss in the high‐temperature region of 500–1,000°C, showing the thermal stability of the catalyst. FTIR study shows highly bonding in metal atoms. These samples have been tested for photocatalytic degradation of brilliant green dye. 5 mol% Mn‐doped TiO2 is having nearly four times more photocatalytic activity than pure TiO2. In addition, Mn‐doped TiO2 has shown excellent photodegradation of a mixture of three dyes namely, rhodamine B, brilliant green, and methylene blue.

Ag doped TiO2 nanoparticles with different metallic content (0.0, 0.1, 0.15 and 0.2 wt.%) were prepared by using EDTA-Glycol method. For the sake of comparison blank TiO2 sample is also prepared using same method. All the samples have been characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), and transmission electron microscopy (TEM). X-ray diffraction technique revealed that Ag-doped TiO2 has anatase structure and as the concentration of Ag increases the particle size will get decreases. The morphologies of TiO2 samples are influenced by doping Ag as shown by SEM images. The present work is mainly focused on the enhancement of photocatalytic reactivity of as synthesized samples by the photodegradation of 4BS under visible light irradiation using a LED lamp of (15 W) as a light source. A 96.3% of photodegradation of 4BS dye was achieved by utilizing 1 g/L of Ag-doped TiO2 at pH 6 for 100 min.