不同制备方法对BiOCl材料的形貌、结构与光催化性能的影响研究

对比采用溶剂热合成、传统固相合成与溶胶-凝胶合成技术,制备了四方相BiOC1和Nd3+掺杂BiOCl光催化材料.运用X射线粉末衍射(XRD)、扫描电子显微镜(SEM)及紫外-可见吸收光谱(UV-Vis),研究了不同合成方法所制备BiOCl材料的相结构、形貌和紫外-可见光吸收性能;并以甲基橙溶液为模拟废水,研究了不同方法所制备的BiOCl材料的光催化性能.结果表明:溶剂热合成的BiOCl是由纳米片组装成粒径小于1μm微球,紫外-可见吸收边为335 nm;固相合成所得BiOCl结晶度较高,其片状颗粒粒径约为6μm,紫外-可见吸收边为430n m;溶胶-凝胶合成法制得BiOCl片状颗粒粒径约为3～4 μm,紫外-可见吸收边为430 nm.进一步地对比研究了稀土离子Nd3+掺杂前后BiOCl样品的结构、紫外-可见光吸收特性,可以发现,Nd3+掺杂后样品的相结构及形貌均无变化,但吸收边均发生不同程度的红移,以溶胶-凝胶法制得的样品效果最为明显,并具有最优的光催化性能.     

A Facile Controllable Synthesis, Growth Mechanism, and Photocatalytic Properties of Nanoscale BiOCl

Nanoscale tetragonal BiOCl samples have been synthesized using Bi[SC12H25]3 and CHCl3 as bismuth and chlorine sources by solvothermal reactions. The structure, morphology, and formation process have been investigated by SEM, TEM, HRTEM, XRD, and EDX analyses. The layered crystal structure feature of BiOCl may induce the growth of nano plates, which can subsequently aggregate into 3D spherical or flower-like microstructures under the presence of ethanol. The reaction temperature and the identity of secondary solvent influence the morphology. The yield of BiOCl depends on the completeness of the reaction and the degree of a competition reduction of BiOCl to Bi by ethanol. The as-synthesized 3D quasi-spherical BiOCl sample has an optical band gap of 3.15 eV, and shows much better photocatalytic performance on the degradation of methyl orange than that of commercial P25.     

源于铋玻璃的富氧空位BiOCl光催化材料的原位合成及性能

氧空位对光催化材料的可见光吸收范围与电子-空穴分离效率都具有重要影响,铋玻璃内含有丰富的氧空位缺陷.采用盐酸腐蚀铋玻璃原位合成BiOCl光催化材料,研究了玻璃网络外体对氧空位浓度的影响规律,并利用X射线衍射(XRD)、扫描电子显微镜(SEM)、透射电子显微镜(TEM)以及电子顺磁共振(EPR)对合成的BiOCl材料的结...     

MOF-808/BiOCl复合材料的制备及其光催化性能

将高稳定性的MOF-808与BiOCl结合,采用简便的水热法制备出新型MOF-808/BiOCl复合异质结材料。以环丙沙星(CIP)为污染物,探究复合材料MOF-808/BiOCl对CIP的光催化性能。发现含有10% MOF-808的复合材料(MOF-808/BiOCl-10%)表现出最佳的光催化活性。在紫外光照射20 min内,MOF-808/BiOCl-10%对CIP的光催化降解效率高达94.7%。通过X射线粉末衍射、扫描电镜、红外光谱、荧光光谱、紫外可见漫反射光谱、光电流、电化学阻抗等表征技术来考察材料的物相组成、形貌以及光电化学性质。紫外可见漫反射光谱的结果表明,MOF-808/BiOCl-10%材料光吸收范围得到提高。同时进行了自由基捕获实验。基于以上实验数据,提出了MOF-808/BiOCl复合材料可能的光催化机理。     

Photocatalytic degradation of methylene blue over N-doped MnWO4 under visible light irradiation

In recent years, the transition-metal tungstate materials with formula MWO₄ have attracted much attention in photocatalytic environmental purification due to their interesting structural and optical properties. Among the others, manganese tungstate (MnWO₄) has attracted particular attention because of its appropriate bandgap energy (2.67 ​eV) with tunable optical and electrical properties, chemical stability, and low cost which makes a suitable photocatalyst. Nevertheless, the manganese tungstate (MnWO₄) based materials are less explored as visible light responsive photocatalysts for wastewater purification. Hence, both parent and N-doped MnWO₄ are synthesized by a hydrothermal method with different nitrogen contents (5, 10, and 15 ​mol%). The as-prepared photocatalysts were characterized by XRD, SEM-EDS, TEM-SAED, FT-IR, UV–Vis DRS, XPS and PL techniques. The photocatalytic activities of the synthesized samples were evaluated by degradation of methylene blue (MB) dye under the visible light irradiation. All the N-doped MnWO₄ samples exhibited enhanced visible-light photocatalytic activity compared to the parent MnWO₄, and the optimal dopant amount of nitrogen was 15 mol% for the best photocatalytic activity. The active species generated during the process of MB degradation are investigated by scavenging experiments. Further, the reusability of the 15 ​mol% N-doped MnWO₄ photocatalyst was examined in three consecutive catalytic runs.     

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。     

pH调节剂对BiOCl结构和光催化降解RhB的影响

以水解法合成了BiOCl纳米片,并考察了制备溶液的pH调节剂对BiOCl晶形、形貌、孔径分布和比表面积、化学组成、光学性质及催化性能的影响.采用X射线衍射谱(XRD)、扫描电子显微镜(SEM)、N_2吸附、X射线光电子能谱(XPS)和紫外-可见漫反射光谱(DRS)对所合成的BiOCl样品进行表征.表征和催化结果表明:pH调节剂为NaOH和Na_2CO_3的BiOCl样品含有杂质,pH调节剂为NH_4OH的BiOCl为纯四方晶型材料;3种pH调节剂合成出的BiOCl都为纳米片,纳米片粒子大小顺序为Na_2CO_3NH_4OHNaOH,孔径大小顺序为Na_2CO_3NaOHNH_4OH;以NaOH、Na_2CO_3、NH_4OH为pH调节剂合成出的BiOCl的带隙能分别为3.27、3.21、3.15 e V,表面元素均为B~(3+)、O~(2-)和Cl~-;可见光降解罗丹明B的顺序为NH_4OHNa_2CO_3NaOH.并且,我们阐述了pH调节剂对光催化降解RhB的影响机理.     

Photocatalytic degradation of azo dyes in aqueous solutions under UV irradiation using nano-strontium titanate as the nanophotocatalyst

Research on photocatalytic degradation rate of azo dyes using nano-strontium titanate in photocatalysis process was the main goal of present study. In this regard, the influence of the main operating parameters such a photocatalyst concentration, dye concentration, temperature, pH and the presence of hydrogen peroxide upon dye removal rate under UV irradiation was studied. The absorbance of samples was measured by a UV–Vis spectrophotometer. The structure and morphology of nano-powder were investigated using scanning electron microscopy and crystalline structure by X-ray diffraction spectroscopy. The results reveal that nano-strontium titanate has high and significant photocatalytic activity and in comparison with nano-titanium dioxide was superior photocatalyst.     

Photocatalytic degradation of 2,4,6-trinitrotoluene

A Pt/TiO2 photocatalyst was used in the photocatalytic degradation of 2,4,6-trinitrotoluene (TNT) under the irradiation of the simulated sunlight. The results show that the destruction of TNT is faster and more complete with the photocatalyst. The photocatalytic degradation of TNT follows first order kinet-ics. The transformation of nitryl groups of TNT molecules into nitrite and nitrate ions may be acceler-ated in the presence of the Pt/TiO2 photocatalyst. Compared with that without the catalyst, the concentration of nitrate ions was improved 32.3 times within 2.5 h.     

BiOCl/蒙脱土复合光催化剂的制备及其光催化活性

为优化BiOCl光催化剂的结构,改善其对有机污染物的吸附性能,进而提高光催化反应活性,采用超声辅助化学沉淀法制备了BiOCl/蒙脱土(MMT)复合光催化剂,并考察了MMT质量分数(w(MMT))对复合光催化剂结构及光催化反应活性的影响。 X射线粉末衍射(XRD)、扫描电子显微镜(SEM)、傅里叶红外光谱(FTIR)和紫外-可见漫反射光谱(DRS)等的表征结果表明,所得催化剂呈微球状结构,禁带宽度为3.24 eV。 随着w(MMT)的增加,催化剂的微球状结构逐渐被破坏,但带隙能未发生明显变化。 以8-羟基喹啉为目标物考察了复合催化剂的吸附及光催化反应活性。 结果表明,随着w(MMT)增加,催化剂对8-羟基喹啉的吸附和光催化氧化活性逐渐增加,这可归因于与MMT的复合增大了比表面积并降低了光生载流子复合效率。 当w(MMT)为15%时,催化剂的吸附及光催化性能达到最佳,光照50 min后,8-羟基喹啉的降解率达到85.6%,矿化率达到51.0%。 光生空穴和超氧自由基负离子为主要的氧化活性物种。 复合催化剂还可高效降解邻苯二酚和对氨基苯甲酸。 同时,复合光催化剂表现出较强的化学稳定性,表明其具有较强的实际应用价值,可用于处理含有机酚类污染物的工业废水。     

Heterojunction of BiPO4/BiOBr photocatalysts for Rhodamine B dye degradation under visible LED light irradiation

BiOBr synthesized by alcoholysis precipitation is used in the preparation of BiPO₄/BiOBr composites by adding H₃PO₄. Pristine BiOBr and a series of BiPO₄/BiOBr composites have been successfully synthesized using an entirely room-temperature production process. X-ray powder diffraction, scanning electron microscopy, High-resolution transmission electron microscopy, X-ray photoelectron spectroscopy, UV–vis absorption spectroscopy were used to investigated the bulk structure, surface morphology, element composition and optical properties of the samples. The degradation effect of different proportions of BiPO₄/BiOBr composites, BiOBr and BiPO₄ on Rhodamine B (RhB) was evaluated under visible LED light irradiation. Compared to pure BiOBr and BiPO₄, the as-synthesized BiPO₄/BiOBr composites showed enhanced performance, with 30% BiPO₄/BiOBr composite showing the best performance, as it could degrade 95.66% of RhB (100 ml, 15 mg/L) within 120 min. The enhanced photocatalytic activity of BiPO₄/BiOBr was attributed to the heterojunction formation between BiOBr and BiPO₄ and efficient charge separation.     

Fabrication of FeOOH/BiOCl Nanocomposites with Enhanced Visible Light Photocatalytic Activity

BiOCl as a two‐dimensional layer ternary oxide semiconductor, has been widely used in energy and environmental area due to its non‐toxicity, price and the good photocatalytic performance. However, BiOCl has a wide bandgap and can only absorb ultraviolet light, which limits its solar energy conversion efficiency for practical application. Herein, we report a facile synthesis of FeOOH/BiOCl nanocomposites by hydrothermal method. The results of XPS and FT‐IR indicated that FeOOH has been loaded on the nanocomposites. The chemical and optical properties of the nanocomposite are well‐characterized. The nanocomposite showed much more excellent photocatalytic performance compared with the individual FeOOH and BiOCl single component. Reactive specie trapping experiment indicated that · O^2– and h⁺ were the two main active species during the photocatalytic process of FeOOH/BiOCl nanocomposites.     

BiOCl/NaBiO_3复合材料的原位合成及光催化性能

利用HCl与Na Bi O3反应原位制备了结构可控的Bi OCl/Na Bi O3复合光催化材料.通过X射线粉末衍射(XRD)、紫外-可见漫反射光谱(UV-Vis-DRS)和扫描电子显微镜(SEM)等技术对其晶相组成、光吸收特性和表面形貌进行了表征,并评价了样品在可见光和紫外光下的光催化性能.结果表明,尽管Bi OCl几乎没有可见光活性,但27.4%Bi OCl/Na Bi O3在可见光下却表现出明显高于纯Bi OCl和Na Bi O3的光催化活性.由于紫外光照可以有效激发Bi OCl,所有组成的复合Bi OCl/Na Bi O3都显示出高于纯Bi OCl和Na Bi O3的光催化活性,其中47.6%Bi OCl/Na Bi O3具有最大光催化活性.研究了加入不同活性物种的捕获剂对光催化效率的影响,结合荧光实验结果和样品能带结构推测了复合材料光催化过程中光生载流子的传输行为.结果表明,Bi OCl/Na Bi O3催化活性增强主要归结于2种材料之间形成了有效的异质结构,其内建电场能够促进光生载流子的传输和分离;羟基自由基在光催化降解过程中是主要的活性物种.     

Photocatalytic degradation of methyl red by porous zinc hydroxide under visible light irradiation

In the present study, porous zinc hydroxide was successfully prepared via a simple sol–gel route. The synthesized porous zinc hydroxide was characterized using scanning electron microscopy (SEM), X‐ray diffraction (XRD), transmission electron microscopy (TEM), and Brunauer–Emmett–Teller (BET) techniques. In addition, the prepared porous zinc hydroxide was studied as a photocatalyst for the degradation of methyl red. The degradation behavior of porous zinc hydroxide was investigated systematically. The experimental results showed that the obtained porous zinc hydroxide displayed excellent degradation efficiency (89%) under visible light irradiation. Thus, porous zinc hydroxide can be used as an effective photocatalyst for the degradation of methyl red, which can be used for industrial wastewater treatment.     

超声微乳法合成TiO2-SiO2催化剂可见光光催化降解亚甲基蓝

采用可见光下亚甲基蓝的光催化降解为模型反应,考察了超声微乳法经钛酸丁酯水解合成的纳米TiO2-SiO2催化剂的性能,并用XRD和BET对催化剂进行了表征。结果表明:硅胶的加入有效地提高了TiO2-SiO2催化剂的热稳定性,抑制了热处理过程中TiO2由锐钛矿相向金红石相的转变和晶粒的长大。随着焙烧温度和TiO2含量的增加,TiO2的晶粒变大,但比表面积减少。TiO2-SiO2的光催化活性明显改善,可见光照射120min,31%TiO2/SiO2催化剂存在下,有84%亚甲基蓝光催化降解。31%TiO2/SiO2催化剂光降解亚甲基蓝的能力大大优于Degussa P-25和纯TiO2,其降解亚甲基蓝的反应速率常数分别为P-25和纯TiO2的8倍和10倍。     

全氟辛酸(PFOA)紫外光化学降解特性与机理

全氟辛酸(PFOA)因其在环境介质中的稳定性、持久性和生物累积性,常规方法很难将其降解,或必须付出昂贵的代价.近几年,一些研究者利用紫外光化学降解环境介质中的PFOA,显示出了优良的应用前景.本文结合国内外研究者近年来的工作,介绍了紫外光化学降解PFOA的原理与特性,对各体系中关键介质的作用与机理进行了讨论,针对紫外光化学降解PFOA存在的问题提出了见解,并对该领域研究的趋势进行了展望.     

竹炭负载氧空位型BiOI/BiOCl复合光催化剂脱硝机理

以竹炭为载体,采用溶剂热法制备了氧空位(OV)型BiOI/BiOCl光催化剂,考察了温度和光照强度对其催化脱硝性能的影响,采用SEM、XPS、XRD、PL、Uv-vis等表征方法研究了该复合光催化剂上的脱硝机理。结果表明,在氙灯功率500 W、温度30℃时,最佳脱硝效率可达73%。氧空位改性可以增大竹炭的比表面积和孔容,提高其吸附能力,同时使C=O双键和-COO形式的酸性官能团分解为C-O官能团;OV改性还增加了光催化活性位点,减少了电子空穴对复合概率,从而提高了对NO的光催化降解效率。     

声化学辅助溶剂热合成高光催化性能的BiOCl光催化剂

以五水硝酸铋和氯化钠为原料,乙二醇(EG)和水作溶剂,通过声化学辅助溶剂热法合成了系列BiOCl纳米晶光催化剂。应用氮气物理吸附、X射线粉末衍射(XRD)、扫描电镜(SEM)、傅里叶变换红外光谱(FTIR)、紫外-可见(UV-Vis)漫反射(DRS)和光电流等测试手段对所制备的光催化剂进行了表征。在汞灯和氙灯照射下,以苯酚和甲基橙为水体模型污染物,系统考察了超声辐射时间和醇水比(V_EG/V_H2O)对BiOCl光催化剂性能的影响。结果表明,当超声辐射时间为60 min,V_EG/V_H2O=1/4时,合成的BiOCl表现出最佳的光催化活性,为常规沉淀法制备的BiOCl的3.3倍。活性提高的主要原因是,适当时间的超声波辐射和醇水比有利于催化剂比表面积的提高,同时可以丰富催化剂表面羟基(-OH)的数量和提高光生电子和空穴的分离效率。     

High-performance photocatalytic degradation of neutral red over cobalt grafted-mesoporous silica under UV irradiation

Journal of Sol-Gel Science and Technology - Cobalt-grafted-mesoporous silica nanoparticles with the Si/Co molar ratio of 70 were synthesized by using sol–gel method (denoted as Co-MSN)....