Microwave Synthesis, Photoluminescence, and Photocatalytic Activity of PVA-Functionalized Eu3+-Doped BiOX (X = Cl, Br, I) Nanoflakes

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• 作者：Armita Dash ; Shyam Sarkar ; Venkata N. K. B. Adusumalli ; Venkataramanan Mahalingam
• 刊名：Langmuir
• 出版年：2014
• 出版时间：February 11, 2014
• 年：2014
• 卷：30
• 期：5
• 页码：1401-1409
• 全文大小：550K
• ISSN：1520-5827

文摘

We report a facile microwave-assisted green synthetic route for colloidal poly(vinyl alcohol) (PVA)-coated europium (Eu³⁺)-doped luminescent heavy metal bismuth oxyhalide (BiOX; X = Cl, Br, I) nanoflakes at low temperature and examine their structural, optical, and photocatalytic characteristics. PVA coating onto the surface of the nanoflakes endows them with hydrophilic nature. Both Eu³⁺-doped BiOCl and BiOBr nanoflakes exhibit strong optical properties related to Eu³⁺ and Bi³⁺ which are quenched in case of Eu³⁺-doped BiOI matrix. These results are supported by Eu³⁺ photoluminescence lifetime values of 0.61 ms, 0.59 ms, and 8.9 渭s, respectively. The former two matrices have quite similar crystal field environments as deduced from the asymmetric ratios of ⁵D₀ 鈫?⁷F₂ (614 nm) and ⁵D₀ 鈫?⁷F₁ (591 nm) transitions. In addition to possessing interesting photoluminescence properties, a comparison of the photocatalytic activity of Eu³⁺-doped BiOX (X = Cl, Br, I) nanoflakes, with corresponding estimated band gaps of 3.36, 2.74, and 1.67 eV has been evaluated using Rhodamine B (RhB) dye under visible light irradiation. The nanoflakes exhibited 100% dye degradation under visible light irradiation. Eu³⁺-doped BiOCl nanoflakes manifested higher photocatalytic efficiency compared to the other matrices following apparent first-order kinetics. Such a boost in efficiency is attributed to their high surface area to volume ratios, layered crystalline structures, indirect band gap nature, and ability to utilize broad bands in the solar spectrum.