H4SiW12O40/polymethylmethacrylate/polyvinyl alcohol sandwich nanofibrous membrane with enhanced photocatalytic activity

• H4SiW12O40/PMMA/PVA sandwich nanofiber membranes were prepared by electrospinning.
• The Keggin structure of H4SiW12O40 has not been destroyed in the sandwich nanofiber membrane.
• The sandwich nanofiber membrane exhibited enhanced photocatalytic activity in the degradation of methyl orange (MO).
• The sandwich nanofiber membrane could be easily separated and reused.
• The photocatalytic degradation of MO by the sandwich nanofiber membrane was driven by the reductive pathway.

Nanofibrous membranes of H4SiW12O40/polymethylmethacrylate (PMMA)/polyvinyl alcohol (PVA) were prepared by electrospinning technique. The sandwich structure and element composition of the membranes were characterized by scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDX), Fourier transformation infrared spectroscopy (FT-IR), and X-ray photoelectron spectroscopy (XPS). The characterization indicated that H4SiW12O40 has been successfully loaded into the upper and bottom layers of the sandwich nanofibrous membrane, while the Keggin structure of H4SiW12O40 was preserved. The as-prepared H4SiW12O40/PMMA/PVA sandwich nanofibrous membranes exhibited greatly enhanced photocatalytic efficiency (≥94.0%) in the degradation of methyl orange (MO) under ultraviolet irradiation, outperforming H4SiW12O40 powder (4.6%) and H4SiW12O40/PMMA composite nanofibrous membrane (13.8%). Notably, the sandwich nanofibrous membrane could be easily separated from aqueous MO solution and the photocatalytic efficiency of the membrane had little change after three photocatalytic cycles. The great performance of the as-prepared membrane may be attributed to the water tolerance of the sandwich nanofibrous membrane and the stability of H4SiW12O40 in the membrane. The photocatalytic mechanism of the sandwich nanofibrous membrane was also discussed.

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