Sol-Gel synthesis of transition metal (Mn, Fe) doped Tin oxide (SnO2) nanoparticles with improved photocatalytic activity under visible light irradiation

Tin oxide (SnO2), a wide-bandgap semiconductor, suffers from low photocatalytic efficiency under visible light due to limited light absorption and a high rate of electron-hole pair recombination. It shows a way to successfully dope SnO2 with transition metals (iron and manganese) to enhance photocatalytic performance in enough to work beyond these restrictions. The simplistic sol-gel technique was used to produce nanocrystalline Sn0.09Mn0.05Fe0.05O2 particles, which exhibited an average crystallite size of roughly 3–5 nm as confirmed by X-ray Diffraction (XRD) and Transmission Electron Microscopy (TEM) examination. The optoelectronic properties of the material were significantly enhanced by the successful incorporation of Mn and Fe into the SnO2 lattice. The reduction of optical band gap from 4.23 eV in pristine SnO2 to 3.23 eV in doped sample, which extended light absorption into the visible spectrum, was an important achievement. Additionally, the doped sample showed notable quenching in photoluminescence (PL) spectroscopy, indicating reduced charge carrier recombination a critical component of increased catalytic activity. These characteristics immediately contributed to the remarkable photocatalytic degradation of methyl orange (MO) dye by the Mn–Fe doped SnO2 nanoparticles, which achieved 44% degradation in 120 min, exceeding the 30% efficiency of pristine SnO2 under the identical conditions. According to these studies, doping SnO2 with Mn and Fe is a successful method of modifying band structure and charge carrier dynamics, resulting in a more effective photocatalyst for cleaning up the environment.