Mn-doped SrTiO3 Perovskite: Synthesis and Characterisation of a Visible Light-active Semiconductor

Abstract

This study focuses on the synthesis and characterisation of Mn-doped SrTiO3 using the citric method. As-prepared samples featured a non-porous microstructure with a mean particle size of approximately 5 μm, composed of sintered submicron crystallites. Manganese was successfully incorporated into the perovskite structure as Mn4+, with a homogeneous distribution across the Sr and Ti positions. The doping induced a distinctive dark brown hue, indicating significant visible light absorption. A pronounced band gap shift from 3.32 to 2.92 eV was revealed via Tauc analysis of the Kubelka-Munk function. Both the SrTiO3 and Mn-doped SrTiO3 samples demonstrated a high adsorption capacity exclusively for cationic dye (Methylene Blue) at pH 10, with the Mn doped sample showing slightly enhanced removal efficiency, reaching a maximum adsorption capacity of 310.7 mg.g-1. The selective adsorption at high pH can be attributed to electrostatic interactions between the perovskite surface and MB molecules. This combination of high adsorption capacity and a reduced band gap highlights the material's potential for photocatalysis applications.