| Polyoxometalate based one-dimensional nano arrys of (PEI/PSS)/(PAH/PSS)3(PAH/PW12)8(PEI=polyethylenimine, PSS polystyrene sulfonate, PAH=poly(allylamine hydrochloride, PW12H3PW12O40·nH2O) have been fabricated in the template of AAO and of PC via adhesive attraction between polymer electrolyte and the template inner surface, electrostatic interactions between the oppositively charged electrolytes, as well as electrostatic interactions between positively charged electrolyte and negatively charged PW12which is an excellent photocatalyst, by using layer-by-layer (LBL) method. The structure of nano tubular arrays was characterized by UV-vis, FTIR, EDX and SEM methods. The diameter and wall-thickness of the nanotubes were founded to be180±20nm and30nm respectively. More importantly, the newly fabricated POM nanotubular arrays in the two different templates, AAO and PC, exhibited excellent effect to photodegradation of Rhdamine B (RhB) in a mild condition, due to the nano confinement effect of the nano tubular arrays, and much better results were obtained when AAO was used as the template. TOC changes were measures during the reaction process and final products of the RhB degradation were analysed using GC/MS method. Besides that, the production of hydroxyl radicals (·OH) on the surface of UV-irradiated POM hybrids were detected by a photoluminescence technique by using terephthalic acid as a probe molecule, indicating that the mechanism of photodegradation process was of hydroxyl radicals.In addition, the heterogeneous catalysts were synthesized by reacting tetrabutylammonium bromide with two different Keplerate-type POMs [MO132O372(H2O)72(CH3COO)30]42-and [MO132O372(H2O)72(SO4)30]72-({Mo132}). Their photodegradation properties to RhB were also studied in this paper. The result of catalysis effect with42-negative-charged {Mo132} was found to be better than72-negative-charged {Mo132} and it was proved as the mechanism of hydroxyl radicals. |
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