Structural and photocatalytic studies of Mn doped TiO2 nanoparticles

Mn-doped TiO2 nanoparticles (Ti1−xMnxO2; where x = 0.00–0.10) were synthesized by sol–gel method. The synthesized products were characterized by X-ray diffraction (XRD), scanning electron microscope (SEM), transmission electron microscope (TEM) and UV–Vis spectrometer. The SEM and TEM micrographs revealed the agglomerated spherical-like morphology and measurements show that the size of crystallites is in the range of 10–20 nm. Optical measurements indicated a red shift in the absorption band edge after Mn doping. Direct allowed band gap of undoped and Mn-doped TiO2 nanoparticles measured by UV–Vis spectrometer were 3.00 and 2.95 eV at 300 °C, respectively. Photocatalytic activities of TiO2 and Mn doped TiO2 were evaluated by irradiating the sample solution of methylene blue (MB) dye under ultraviolet and visible light exposure. It was found that Mn-doped TiO2 bleaches MB much faster than undoped TiO2 upon its exposure to the visible light as comparison to ultraviolet light. The experiment demonstrated that the photodegradation efficiency of Mn-doped TiO2 was significantly higher than that of undoped TiO2 upon its exposure to visible light.

Graphical abstract3–10 mol % Mn doped TiO2 nanopowders show strong photocatalytic activity under visible light irradiation, which was observed by measuring the degradation of methylene blue. The optimum Mn/Ti ratio was observed to be 3 mol % for photocatalytic applications. In contrast, little degradation was observed for the pure TiO2 powder.Figure optionsDownload full-size imageDownload as PowerPoint slideHighlights► Mn-doped TiO2 nanoparticles were synthesized by a sol–gel method. ► When TiO2 powders calcined at 300–800 °C, the transformations such as anatase to rutile phase occurred. ► Optical measurements indicated a red shift in the absorption band edge upon Mn doping. ► Photocatalytic activity of Mn-doped TiO2 is significantly higher under visible light as compared to UV light. ► Optimum concentration of Mn doped TiO2 was observed to be 3 mol % for photocatalytic applications.