Electrospinning preparation of a H4SiW12O40/polycaprolactam composite nanofibrous membrane and its greatly enhanced photocatalytic activity and mechanism

Abstract

H₄SiW₁₂O₄₀/polycaprolactam (PA6) composite nanofibrous membranes with a minimum average diameter of ∼70 nm were prepared by an electrospinning technique. Characterization with Fourier transform infrared spectroscopy (FT-IR), energy-dispersive X-ray spectroscopy (EDX) and X-ray photoelectron spectroscopy (XPS) indicated that H₄SiW₁₂O₄₀ has been successfully loaded into the PA6 membrane and its Keggin structure was intact. The as-prepared H₄SiW₁₂O₄₀/PA6 membranes exhibited greatly enhanced photocatalytic efficiency (≥96.0%) and excellent reusability in the degradation of methyl orange (MO) under ultraviolet irradiation, which may be attributed to the synergistic effect of PA6 and H₄SiW₁₂O₄₀. The photocatalytic process was likely to be driven by the reductive pathway with a much faster degradation rate due to the electron donation from PA6 to H₄SiW₁₂O₄₀. The hydrogen bonds between H₄SiW₁₂O₄₀ and PA6 could enhance the stability of H₄SiW₁₂O₄₀ in the membrane, so that there was nearly no loss of photocatalytic activity of the catalyst after three cycles of reactions. In view of this, H₄SiW₁₂O₄₀/PA6 composite nanofibrous membranes exhibit potential for practical applications to eliminate organic pollutants from wastewater.