研磨-焙烧法制备La_2O_3/BiOCl复合光催化剂及其对高浓度染料降解性能

Preparation by Grinding-calcination and Photocatalytic Performance of La_2O_3/BiOCl Composite Photocatalysts

首先利用沉淀法合成了BiOCl纳米片,然后利用研磨-焙烧法将La2O3纳米颗粒复合到BiOCl纳米片中,制备了一系列La2O3/BiOCl复合光催化剂（La2O3：1wt%、2wt%、4wt%、8wt%）。运用X射线粉末衍射（XRD）、扫描电镜（SEM）、透射电镜（TEM）、光电子能谱（XPS）、紫外-可见漫反射光谱（UV-Vis DRS）、傅里叶红外光谱（FT-IR）和光致发光（PL）谱等对样品的晶相、光吸收和表面性能等进行了表征。以紫外灯（λ=254 nm）为光源,评价了所制备样品光催化降解高浓度染料酸性橙II（40×10-6）的活性。结果表明,经过研磨-焙烧后该系列催化剂均具有较好的结晶性能,同时2~5 nm的La2O3纳米粒子粘附在BiOCl纳米片表面。200℃焙烧制备的1wt%La2O3/BiOCl催化剂具有丰富的表面羟基,对染料表现出较强的吸附性能。该催化剂表现了最高的光催化活性,活性为纯BiOCl的2.4倍。另外,La2O3/BiOCl中的La3＋提供的氧化-还原势阱可能捕获光生电子,从而阻止了光生电子（e–）和空穴（h＋）的复合,有利于光催化活性的提高。

BiOCl nanoplates were firstly prepared by precipitation method and then La2O3/BiOCl composite photocatalysts with different La2O3 contents（1wt%, 2wt%, 4wt%, 8wt%） were synthesized by grinding-calcination procedure. The physical chemistry properties of the as-prepared photocatalysts were characterized by powder X-ray diffraction（XRD）, scanning electron microscope（SEM）, transmission electron microscope（TEM）, UV-Vis diffuse reflectance spectroscope（DRS）, X-ray photoelectron spectroscope（XPS）, Fourier transformed infrared spectroscope（FT-IR）, and photoluminescence（PL） spectroscope. The photocatalytic activity of the samples was evaluated by photocatalytic degradation of high concentration acid orange II（40×10-6） under UV light（λ=254 nm） irradiation. Results showed that the as-prepared samples have good crystallinity. La2O3 particles with the size of 2–5 nm were closely combined with BiOCl nanoplate after grinding-calcination treatment. La2O3/BiOCl composite photocatalysts with 1wt% La2O3 calcined at 200 displayed the best photocatalytic activity℃ which is 2.4 times of that of pure BiOCl. The produced La2O3/BiOCl has abundant surfaceOH groups and highly suitable adsorption of dye. Moreover, La3＋ could capture the photon-generated electrons（e-） and prevent the recombination of photon-generated and holes（h＋）.