Synergistic effect in heterojunction TiO₂/SnO₂ nanofibers: boosting photocatalytic performance for methylene blue...

Titanium dioxide (TiO₂) is widely applied in water treatment, air purification, self-cleaning surfaces, and other fields owing to its strong oxidizing capacity, excellent chemical stability, low cost, and non-toxicity. However, its practical application as a photocatalyst is severely limited by the extremely low solar light utilization efficiency. To address this defect and enhance the photocatalytic performance of TiO₂ under ultraviolet (UV) and nature light irradiation, TiO₂/SnO₂ composite nanofibers were fabricated via electrospinning combined with calcination processes. SnO₂ possesses high electron mobility as well as stable chemical and thermal properties, the construction of a heterojunction between TiO₂ and SnO₂ is conducive to improving the separation efficiency of photogenerated electron-hole pairs, thereby enhancing the overall photocatalytic activity. The morphology, crystal structure, and photocatalytic properties of the prepared composite nanofibers were systematically characterized using scanning electron microscopy (SEM), X-ray diffraction (XRD), thermogravimetric analysis (TGA), and photocatalytic degradation experiments with methylene blue (MB) as the target pollutant. The results demonstrated that the TiO₂/SnO₂ nanofibers prepared at a TiO₂ : SnO₂ molar ratio of 10 : 1 and a calcination temperature of 450 °C exhibited the optimal photocatalytic activity under UV light, achieving a MB degradation rate of 99% within 60 min. Additionally, the photocatalytic performance of TiO₂/SnO₂ nanofibers under nature light was significantly improved with the calcination temperature of 650 °C: the MB degradation rates after 3 h of irradiation were 42.39%, 66.15%, and 74.06% at 450 °C, 550 °C, and 650 °C, respectively, which represented increments of 12.26%, 36.02%, and 43.93% compared with pure TiO₂. This work provides a feasible strategy for the modification of TiO₂-based photocatalysts and offers technical support for the efficient treatment of dyeing and printing wastewater.