Tailoring the optical and structural properties of SnO2/SeO2 heterojunction nanofibers through electrospinning and thermal treatment

In this work synthesis and characterization of SnO 2 /SeO 2 heterojunction nanofibers fabricated via electrospinning followed by calcination at 500 °C and 600 °C is presented. The study provides a comprehensive analysis of the influence of calcination temperature on the structure, morphology, and optical properties of SnO 2 /SeO 2 nanofibers. Results of the morphology analysis revealed that increasing the calcination temperature induces a reduction in both crystallite and nanofiber diameters, promotes the formation of structural defects, and facilitates the emergence of isolated nanoparticles on fiber surfaces. X-ray diffraction and X-ray photoelectron spectroscopy analyses confirmed the coexistence of amorphous SeO 2 and polycrystalline SnO 2 phases, forming heterojunctions, in which the density of structural defects and oxygen vacancies increases with increasing calcination temperature. The analysis of the optical properties of the produced SnO 2 /SeO 2 nanofibers showed strong ultraviolet absorption accompanied by a temperature-dependent narrowing of the optical band gap from 2.77 eV to 2.47 eV, attributed to defect-induced energy levels within the band structure. These findings demonstrate that controlling the parameters of the calcination process enables the tuning of the optical and structural properties of SnO 2 /SeO 2 nanofibers, making them promising candidates for applications in optoelectronics, photocatalysis, and advanced photovoltaic devices.