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 Sn_0.09Mn_0.05Fe_0.05O₂ 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.

Water contamination by synthetic dyes poses a major environmental challenge, demanding efficient and sustainable remediation strategies such as photocatalysis. In this study, sulfur–graphene nanoplatelet (GNP) composites were synthesized in varying weight ratios and evaluated for their photocatalytic efficiency in degrading methylene blue (MB) and methyl orange (MO) dyes under visible light. While such composites are commonly explored for energy storage, their potential in photocatalysis remains underutilized. The structural and optical features of the synthesized materials were systematically examined, revealing that increased GNP content led to enhanced crystallinity and improved charge separation. Among the prepared samples, the composite with the highest GNP concentration (SG-18) demonstrated 53% and 21.74% efficacious efficacy in first run for MB and MO dyes respectively under 100 min (10 mg catalyst with 250 ml and 150 ml of MB and MO dye solutions respectively). These findings highlight the potential of sulfur–GNP nanocomposites as low-cost, metal-free photocatalysts for environmental cleanup applications.

In this manuscript, we are reporting on the influence of MWNTs (multiwalled carbon nanotubes) on the structural, bonding, and surface morphological response on sulfur nanoparticles. Sulfur and multiwalled carbon nanotube (MWCNT) composites are formed using the solution casting method. The concentration of MWCNTs (0.01 and 0.05) and sulfur (0.99 and 0.95), respectively, was taken in weight ratios during fabrication of the composites. These fabricated composites have been characterized using XRD (X-ray diffraction), FESEM (field emission scanning electron microscopy), and FTIR (Fourier-transform infrared spectroscopy) techniques. XRD spectra reveal that the crystallite size distribution was in the range of ca. 55 nm to 78 nm, as well as enhanced crystallinity upon increasing the concentration of MWCNTs in sulfur composites. Dislocation density and strain have been found to be increased in composites showing increased augmentation of MWCNTs (i.e., S95% MWCNT5%), while FESEM images confirm the uniform distribution of MWCNTs in sulfur composites, along with round structures at the nanoscale range. FTIR spectra depicted the bending and stretching of C-H bands. Composites with a higher concentration of MWCNTs show slightly more stretching vibrations. This indicates the further delocalization of electrons, which reveals that as MWCNTs’ concentration is increased, electrical conductivity enhances, showing that MWCNTs could perform better in electrical industries. The further delocalization of electrons also expresses that free electron–hole pair formation is better in composites with a higher concentration of MWCNTs, accounting for the fact that the photocatalytic response may increase in composites with a higher concentration of MWCNTs. Overall, it can be said that as the MWCNT concentration is ameliorated, the composites show a more crystallized structure with more vibrations. This characteristic of MWCNTs/sulfur composites is useful in photocatalytic response as well as in cathode materials in sulfur batteries.