摘要/Abstract

采用简单的一步水热法，制备了一系列BiOCl-ov/坡缕石（PGS）复合材料x B/P（x是复合材料中BiOCl-ov的摩尔含量）.通过扫描电子显微镜（SEM）、粉末X射线衍射（XRD）、X射线光电子能谱（XPS）、N₂吸附-脱附、红外光谱（FT-IR）、紫外-可见漫反射光谱（UV-Vis DRS）、荧光光谱（PL）和电化学阻抗谱（EIS）对复合光催化剂的结构、形貌和光学性质以及电化学性质做了详细的表征.研究了催化剂在可见光条件下对芳香醇的选择性氧化的催化性能，结果表明，以所得复合材料为催化剂，在可见光照射下，苯甲醇转化率达到了78%，产物苯甲醛的选择性达到了86%，且催化剂的光稳定性良好.
关键词: 坡缕石, BiOCl-ov, 可见光催化, 芳香醇, 选择性氧化
A series of BiOCl-ov/palygorskite (PGS) nanocomposites (abbreviated as x B/P, where x is the molar content of BiOCl-ov in the composites) were synthesized by simple one-step hydrothermal method. The structure, morphology and photoelectrochemical properties of the nanocomposites have been thoroughly characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), N₂ adsorption-desorption, Fourier infrared spectroscopy (FT-IR), ultraviolet-visible diffuse reflectance spectroscopy (UV-Vis DRS), fluorescence spectroscopy (PL) and electrochemical impedance (EIS) spectra. As a typical rodlike natural mineral, PGS was commonly used as absorbent in many fields. Its photocatalytic properties was always ascribed to the defects in its crystal lattice after the acidic treatment, which would give contribution to the photoinduced electron conductions in its bulky nanoparticles. On the other hand, as a typical layered p-typed semiconductor, BiOCl-ov was widely used in many oxidations due to the many of oxygen vacancies existed in its nanostructure. The combination of rodlike PGS and layered BiOCl-ov could be successfully carried out through the formation of the nanocomposites due to their respective crystal structure as well as their catalytic activity. So the BiOCl-ov/PGS nanocomposites were well prepared according to the advantages of PGS and BiOCl-ov. With the carefully investigation of the structure of the nanocomposites, the results showed that the catalysts were successfully prepared. The structures of BiOCl-ov and PGS were all well remained after the preparing process. The photocatalytic activity of the prepared BiOCl-ov/PGS was detected through the selective oxidation of aromatic alcohols under visible-light conditions. It found that BiOCl-ov/PGS showed promising activity for the photocatalytic oxidation of alcohols under the irradiation of visible light. The conversion of 78% of benzalcohol as well as the selectivity of 86% of benzaldehyde was reached with the catalysis of the nanocomposites in the photocatalytic oxidation of benzalcohol. Some of the other substrates, including the derivatives of benzalcohol as well as diphenylmethanol could be well oxidized. Moreover, the nonaromatic substrate, that is, phenethyl alcohol, it was always thought to be not easy to be oxidized one, could also be oxidized to corresponding phenylacetaldehyde with high conversion (89%) and selectivity (99%). Meanwhile, the catalyst possessed well light stability. The photocatalytic mechanism of the oxidation was also investigated through the active species capturing experiments. It showed that the major active species of the oxidation system was ·O₂^- and ·OH radicals.
Key words: palygorskite, BiOCl-ov, visible light catalysis, aromatic alcohol, selective oxidation


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