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

Nanofibrous membranes of H 4 SiW 12 O 40 /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 H 4 SiW 12 O 40 has been successfully loaded into the upper and bottom layers of the sandwich nanofibrous membrane, while the Keggin structure of H 4 SiW 12 O 40 was preserved. The as-prepared H 4 SiW 12 O 40 /PMMA/PVA sandwich nanofibrous membranes exhibited greatly enhanced photocatalytic efficiency (≥94.0%) in the degradation of methyl orange (MO) under ultraviolet irradiation, outperforming H 4 SiW 12 O 40 powder (4.6%) and H 4 SiW 12 O 40 /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 H 4 SiW 12 O 40 in the membrane. The photocatalytic mechanism of the sandwich nanofibrous membrane was also discussed.