Mn-BiOCl的制备及其光催化活性研究

以氧化铋、四水氯化锰为原料,盐酸为溶剂,采用水解法制备了Mn与Bi具有不同摩尔比率的Mn-BiOCl光催化剂。采用X射线衍射(XRD)、高分辨透射电子显微镜(HRTEM)、透射电子显微镜(TEM)、紫外-可见漫反射光谱(UV-Vis DRS)、电子衍射(SAED)、表面光电压光谱(SPS)等对其进行了表征。以甲基橙为光催化反应模型化合物,评价了Mn-BiOCl光催化剂的紫外光催化活性。并研究了甲基橙降解过程中的活性物种。结果表明：Mn的含量对Mn-BiOCl光催化剂的催化活性有重要影响。当Mn与Bi的物质的量之比为0.25% 时,制备的Mn-BiOCl光催化剂催化活性最高,甲基橙的光催化降解率达到95.1%。     

Solvothermal synthesis of three-dimensional microspherical bismuth oxychloride self-assembled by microspheres

Uniform BiOCl microspheres have been synthesized via a facile solvothermal route. The structural features of the as-prepared BiOCl samples were systematically characterized by the X-ray powder diffraction (XRD), and field emission scanning electron microscopy (FE-SEM). The SEM characterization results indicated that BiOCl microspheres possessed a superstructure composed of several hierarchical microspheres, which were assembled by numerous two dimensional nanosheets. This kind of special BiOCl 3D microstructure exhibited a large BET surface area of about 14.24 m² g⁻¹. Besides, the photocatalytic properties of BiOCl hollow microsphere sample and sheet-like sample were investigated in detail. Significantly, BiOCl hollow microsphere sample presented faster degradation rate toward RhB even under visible light, which should be attributed to the unique BiOCl nanosheets self-assembled hollow microspheres.     

采用第一性原理研究非金属掺杂BiOCl的电子结构和光吸收性质

基于密度泛函理论的第一性原理分别研究了不同浓度Br和I掺杂BiOCl体系的能带结构、态密度、形成能和光学性质.研究结果表明,由于Br的4p和I的5p轨道作用,Br和I掺杂可在一定程度上降低BiOCl的禁带宽度,拓宽BiOCl的光吸收范围.Br和I掺杂BiOCl的形成能计算结果表明,Br掺杂BiOCl的稳定性高于I掺杂体系.对于B,C,N,Si,P和S掺杂BiOCl体系,掺杂能级的形成主要由掺杂元素的np轨道贡献,使BiOCl吸收带边红移至可见光区.而S掺杂则位于价带顶位置,有效地降低了BiOCl禁带宽度,使BiOCl响应波长出现红移,且未形成中间能级,不易成为俘获陷阱,因此S掺杂将是一种提高BiOCl可见光光催化活性的改性方法.     

Photocatalytic mineralization study of malachite green on the surface of Mn-doped BiOCl activated by visible light under ambient condition

Manganese doped BiOCl has been synthesized by hydrolysis method and characterized by X-ray diffraction (XRD), scanning electron micrographs (SEM) and diffusive reflectance spectra (DRS) methods. Interesting results have been obtained from diffusive reflectance spectra. XRD results show a decrease in the lattice parameter for Mn-doped BiOCl and UV-vis measurement reveals that there is a shift in the optical absorption edge toward higher wavelength, which indicates a decrease in the band gap upon Mn doping. The increased photocatalytic activity in degradation of malachite green dye by Mn-doped BiOCl might be due to increase in life time of photogenerated electrons and holes due to scavenging of electrons by Mn, charging the particle surface due to electron on the surface, which enhances the adsorption of dye molecules, or/and decreased crystallite size. The effect of key operating parameters have also been investigated. Complete mineralization has been confirmed by COD analysis. An assumptive reaction mechanism has also been proposed.     

Ｂｉ（ Ｎｂ） ＯＣｌ 光 催 化 剂 的 制 备 及 其 可 见 光 降 解罗 丹 明 Ｂ 溶 液 的 性 能

半导体光催化剂作为环境净化材料,具有稳定性好、光效率高、无二次污染等特点,具有广泛的应用前景.过去的研究大都集中在以TiO2为基础的光催化剂上.本文制备了具有层状结构的Bi基氧氯化物Bi(Nb)OCl光催化剂,用XRD、BET和UV-VIS吸收对样品进行了晶相、孔结构和光吸收性能表征,用罗丹明B的降解表征了材料的光催化活性.结果表明,BiOCl和Bi4NbO8Cl均具有可见光光催化降解活性,但两者的反应机理不同,Bi4NbO8Cl是光催化机制,BiOCl是染料光敏化机制.     

分级结构CdS QDs/BiOCl复合光催化剂的制备及其对有机污染物的降解

采用简单液相沉积法制备了分级结构Cd S QDs/Bi OCl复合光催化剂,以XRD,SEM,TEM,HRTEM,XPS,EDS,UV-Vis DRS,PL等测试方法分别表征了样品的物相、形貌、组成、元素含量、光吸收性能以及光电特性,并以罗丹明B(Rh B)和苯酚为模型污染物,分别在可见光和紫外光下评价Cd S QDs/Bi OCl复合光催化剂的催化性能。测试结果表明,粒径为5.5μm的Bi OCl微球由大量纳米片有序堆积而成,所负载的粒径为10~20 nm的Cd S QDs均匀分布在Bi OCl纳米片表面。与纯Bi OCl和Cd S QDs/Bi OCl相比,Cd S QDs/Bi OCl-3%表现出最佳的光催化性能,其对Rh B和苯酚的降解速率常数分别是纯Bi OCl的2.6倍和5.3倍。Cd S QDs/Bi OCl复合光催化剂性能的提高可归结于,分级结构Bi OCl有效防止了片层堆积,有助于Cd S QDs的负载,另外,Cd S QDs的负载拓展了复合光催化剂的光吸收性能,均匀分布的Cd S QDs与Bi OCl形成的异质结促进了光生电子-空穴对的有效分离。     

BiOCl{001}表面原子与电子结构的第一性原理研究

基于密度泛函理论的第一性原理方法研究了BiOCl{001}的三种不同终端面({001}-1Cl, {001}-BiO 和{001}-2Cl)的表面弛豫、能带结构、电子态密度和表面能. 计算结果表明: {001}-1Cl, {001}-BiO和{001}-2Cl表面均发生明显弛豫, 而在双Cl原子层处的层间距变化较大, 但未出现振荡弛豫现象, 其中{001}-1Cl表面弛豫较小. 与体相BiOCl电子结构相比, BiOCl{001}面具有较窄的带隙宽度, 并呈现较强局域性:对于{001}-BiO表面, 其导带与价带均往低能方向发生较大移动, 并且在导带底部出现表面态; 而{001}-2Cl表面的表面态主要出现在价带顶; {001}-1Cl表面的带隙中则无表面态产生; 表面态的出现导致{001}-BiO面和{001}-2Cl面带隙明显减小. BiOCl{001}三种终端表面的表面能分析结果表明, {001}-1Cl表面的表面能最小(0.09206 J·m^-2), 结构最稳定, 而{001}-BiO表面和{001}-2Cl表面的表面能分别为2.392和2.461 J·m^-2. 理论预测{001}-BiO表面和{001}-2Cl表面具有较高的活性, 但在BiOCl晶体生长过程中不易暴露. 本文计算结果为实验获得BiOCl高活性面{001}给予了基础理论解释, 进一步为BiOCl新型光催化材料的应用研究提供理论指导. 关键词： BiOCl{001}表面 表面弛豫 表面能 第一性原理     

First-principles investigation of impurity concentration influence on bonding behavior,electronic structure and visible light absorption for Mn-doped BiOCl photocatalyst

We performed first-principles calculation to investigate the bonding behavior, electronic structure and visible light absorption of Mn_xBi_1−xOCl (x=0, 0.0625, 0.09375 and 0.125) using density functional theory (DFT) within a plane-wave ultrasoft pseudopotential scheme. The relaxed structural parameters are consistent with the experimental results. The bonding behavior, bond orders, Mulliken charges and bond populations as well as formation energies are obtained. The calculated band structures and density of states show that Mn incorporation results in some impurity energy levels of Mn 3d states in forbidden band as well as valence band and conduction band, and that Mn 3d states, for the modest Mn doping concentration, not only can act as the capture center of excited electrons under longer wavelength light irradiation, but also may trap the photo-excited holes, improving the transfer of photo-excited carriers to the reactive sites. Our calculated optical absorption spectra exhibit that the spectral absorption edge is obviously red-shifted and extends to the visible, red and infrared light region due to the incorporation of Mn. Our calculated absorption spectra are in excellent agreement with the experimental results of Mn-doped BiOCl photocatalyst.     

层状氯氧化铋纳米片的制备及其光催化性能测试*——大学综合化学实验的设计

以五水硝酸铋和氯化钾为原料,通过一步式水热合成法制备具有较高光催化活性的层状氯氧化铋催化剂,应用X射线衍射、电子场扫描电镜和紫外可见光谱的表征方法进行材料表征,通过光催化反应研究催化剂对罗丹明B的光催化降解特性。本实验涉及纳米材料的一步式水热合成、纳米材料的结构表征和光催化降解有机污染物的实际应用,综合化学学科知识点于一体。通过实验,本科生能够深入了解并掌握层状氯氧化铋材料的合成和催化性能测试,并且熟悉相关仪器的操作流程,能够把实际教学知识和科研内容有机结合起来,培养并提升学生的化学科研信念和知识储备。     

多级结构BiOCl的可控制备及对药物废水的有效降解

以Bi Cl3为原料,二乙二醇(DEG)为介质,尿素为沉淀剂,采用溶剂热法合成了不同尺寸的多级结构BiOCl微纳米材料.通过X射线衍射仪(XRD)和扫描电子显微镜(SEM)对产物进行了表征.结果表明,沉淀剂用量和溶剂热时间对BiOCl的结晶特性和形貌尺寸有重要影响.控制反应条件制得了粒径大小为1~5μm的BiOCl多级微球.降解药物废水测试结果表明,所制备的催化剂均能有效降解卡马西平(CBZ)和磺胺甲唑(SMZ)溶液,特别是溶剂热时间为30 min,沉淀剂尿素与Bi Cl3的摩尔比为10∶1和15∶1时制得的光催化剂对CBZ和SMZ均表现出最好的光催化活性,且降解率均高于TiO2(P25).