Heterogeneous electron-driven photocatalytic degradation of methylene blue dye using heterojunction SiO2/MoO3 electrospun nanofibers: Synthesis, characterizations and application

This work presents, for the first time, electrospun SiO 2 /MoO 3 nanofibers with optimized band alignment for rapid methylene blue degradation. The structural and optical properties of fabricated nanofibers are characterized using XRD, SEM, XPS, and UV–Vis spectroscopy, confirming their successful fabrication with enhanced stability. Post-catalysis analyses (TGA-DSC, FTIR) confirmed the excellent structural stability of the nanofibers and minimal impact from MB adsorption. The photocatalytic degradation of methylene blue under combined irradiation from a 125 W medium-pressure mercury vapor lamp (UV source) and a 250 W halogen lamp (visible source) was investigated, along with the effects of pH, reaction time, and scavenger presence. The SiO 2 /MoO 3 nanofibers showed a high adsorption rate of 75.6 % and 99.9 % photodegradation within 15 min, following pseudo-second-order kinetics, and had a rate constant of 0.15 g mg −1 min −1 (R 2 = 0.99). Besides that, ANOVA and regression analysis identified irradiation time to be the most significant parameter, followed by pH, which further validated the experimental results. Scavenger tests revealed that hydroxyl radicals (OH • ) were the dominant active species, with superoxide radicals (O 2 -• ) and holes (h + ) playing secondary roles. Moreover, the photocatalyst exhibited 94 % degradation efficiency even after 5th consecutive cycles, illustrating its high stability and reusability. Thus, combining excellent photocatalytic efficacy with nanofibers' structural robustness and recyclability guarantees that SiO 2 /MoO 3 electrospun nanofibers are appropriate alternatives for wastewater remediation. • Synthesis of heterojunctions SiO 2 /MoO 3 nanofibers via electrospinning method. • Photocatalytic degradation of methylene blue (MB) using UV–visible light. • MB Photodegradation follows pseudo-second-order kinetics (R 2 = 0.99). • Hydroxyl radicals as dominant active species for the MB photodegradation.