Structural, Optical and Photocatalytic Properties of Bi2O3/Mn3O4 Nanocomposites

This research aims to develop binary Bi₂O₃/Mn₃O₄ heterostructures for the mineralization of pollutants in water. For this purpose, pure Bi₂O₃, Mn₃O₄, and Bi₂O₃/Mn₃O₄ nanocomposite samples are synthesized. Structural analysis exhibits the formation of a mixed-phase solid oxide solution. This is verified via FTIR spectroscopy where an additional peak observed at 723 cm⁻¹ indicating Bi─O─Mn stretching vibration. The binary Bi₂O₃/Mn₃O₄ nanocomposite has increased visible light absorption and narrow bandgap when compared to pure Bi₂O₃. The synthesized Bi₂O₃/Mn₃O₄ nanocomposite exhibits 76.4% degradation of methylene Blue (MB) under solar light irradiation with a pseudo-first-order rate constant of 0.00572 min⁻¹ superior to pure Bi₂O₃ and Mn₃O₄ nanoparticles. This significant increase in the photocatalytic activity of Bi₂O₃/Mn₃O₄ nanocomposite is due to the direct z-scheme mechanism of charge transfer between Bi₂O₃ and Mn₃O₄ through greater redox potential and generation of surface defects that induce additional active sites for the adsorption of organic dye which trap photoinduced electrons and holes resulting a reduction in electron–hole recombination rate.