Green Synthesis of Mn-doped TiO2 Nanoparticles and Investigating the Influence of Dopant Concentration on the Photocatalytic Activity

A tea plant extract is used in the presence of titanium and manganese sources to synthesize three different concentrations of MnxTi1-xO2 (x = 0.03, 0.05, and 0.1). By substituting Ti atoms for Mn, the lattice of TiO2 is successfully incorporated with Mn. The degradation of Methylene Blue (MB) in the presence of visible light is used to test the photocatalytic activity of the synthesized samples. Among the Mn-doped TiO2 samples, the highest degradation ratio is observed for samples with a dopant concentration of 0.05 at %. A dose of 0.1 g/L and 5 mM of Mn-TiO2 is found to remove 86 % of MB after 35 min of reaction. MnxTi1-xO2 is critically important for speeding up the MB degradation because of electron transfer between Mn and TiO2, and for the regeneration of the Mn4+/Mn2+ cycle on its surface. Optical irradiation of the photocatalytic system under visible light led to higher visible photocatalytic activity than pure TiO2. We propose a novel and environmentally friendly method for preparing photocatalysts to treat organic dyes.