Enhanced photocatalytic activity of SnO ₂ @g-C ₃ N ₄ heterojunctions for methylene blue and bisphenol-A degradation: effect of interface structure and porous nature

In this study, SnO₂@graphitic carbon nitride (g-C₃N₄) heterojunctions were synthesized using a hydrothermal method followed by sonication. The catalytic efficiency of SnO₂@g-C₃N₄ under sunlight was evaluated for methylene blue (MB) and bisphenol A (BPA) degradation. Characterization techniques, including X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), and high-resolution transmission electron microscopy (HRTEM), confirmed the successful formation of SnO₂ nanoparticles on g-C₃N₄ (GCN) sheets with porous morphology. The SnO₂@GCN heterojunction achieved a 97% degradation efficiency for MB in 45 minutes, outperforming pure SnO₂ (65.3%) and g-C₃N₄ (73.8%). Thus, the increase in photocatalytic activity is due to an enhancement in charge separation and an increase in the absorption of sunlight. For BPA degradation, the 5.0% SnO₂@GCN composite demonstrated approximately 99% efficiency within 60 minutes. Additionally, recyclability tests showed good stability after five cycles, with no significant structural changes confirmed by FTIR and FESEM analyses. This study highlights the importance of interface structure and porous morphology in enhancing photocatalytic efficiency, paving the way for effective photocatalysts for wastewater treatment applications.