微波烧结制备Sm掺杂TiO2光催化材料与催化性能表征

采用溶胶-凝胶法结合旋转涂膜法和微波烧结技术制备了Sm掺杂TiO2光催化材料.以罗丹明B为降解物,高压汞灯为光源,考察了微波功率、烧结时间、烧结温度、涂膜层数、稀土掺杂量等因素对TiO2光催化活性的影响;并用XRD、TG-DSC和SEM等对材料进行了表征.结果表明,采用微波分三阶段加热、升温时间65min、烧结温度520℃、涂膜3层、Sm掺杂量x(Sm)＝0.3%时,制备的光催化材料催化活性最高,5h内罗丹明B的降解率可达90%;与传统高温烧结相比,采用微波烧结缩短了烧结时间,降低了烧结温度,提高了光催化材料的活性.SEM检测结果表明,微波烧结样品的粒度比较均匀,晶粒明显细化.     

TiO_2量子点修饰g-C_3N_4及其光催化脱色性能研究

为进一步提高g-C_3N_4光催化活性,采用等孔体积浸渍法制备了TiO_2量子点修饰的g-C_3N_4。研究结果表明TiO_2量子点修饰使g-C_3N_4的XRD衍射峰、表面性质参数、粒径分布和对可见光的吸收有显著影响。以罗丹明B为模拟污染物,在模拟太阳光照射下对所制备TiO_2/g-C_3N_4光催化性能进行了测试。结果表明,经TiO_2量子点修饰后g-C_3N_4光催化性能显著增强,当TiO_2/g-C_3N_4质量比为3%时,所制备样品具有最高的活性。捕获剂测试结果表明,·O2-离子是光催化降解反应中主要的活性物种。     

NaBH_4还原改性TiO_2(B)及光催化性能研究

以TiCl_4为原料,在(CH_2OH)_2溶液中通过一步水热法制备单斜相二氧化钛[TiO_2(B)]。使用不同质量含量NaBH4对TiO_2(B)进行还原改性,调控其内含Ti3+的浓度,合成了含Ti~(3+)的TiO_2(B)-NaBH_4X样品。采用X射线衍射仪(X-ray diffraction,XRD)、拉曼光谱仪(Raman spectroscopy)、紫外-可见漫反射光谱仪(UV-visible diffuse reflectance spectroscopy,UV-DRS)、X射线光电子能谱仪(X-ray photoelectron spectroscopy,XPS)对材料进行表征。改性后TiO_2(B)-NaBH4X样品保持其原有晶体结构,并未发生相变,仅有结晶度的改变。原始TiO_2(B)禁带宽度为3.15 eV,通过改性,Ti~(3+)的存在改变了禁带宽度,成功地将禁带宽度降低到2.82 eV,将吸光区域扩展到可见光区域。通过可见光光催化分解水制氢与可见光降解甲基橙试验,确立了TiO_2(B)-NaBH_43样品有最好的可见光光催化活性,产氢速率达到0.58μmol·h~(-1)·g~(-1),6 h降解率达到40%。     

La/TiO_2制备及其光催化降解浮选药剂酯-105的研究

采用溶胶-凝胶法制备稀土元素La掺杂TiO_2(La/TiO_2)纳米光催化剂,通过X射线衍射(XRD)、紫外-可见漫反射(UV-Vis DRS)和低温N2物理吸附测试手段对其进行表征,并以浮选捕收剂酯-105为处理对象考察了溶液初始p H值、La掺杂比、煅烧温度、光照强度、催化剂用量以及催化剂重复利用对催化剂活性的影响。表征结果表明,La的掺杂能够抑制TiO_2的晶粒生长,增大其比表面积,扩大其对可见光的响应,从而提高其光催化活性;煅烧温度过高会因TiO_2发生烧结团聚而使其粒径增大、比表面积减小,从而影响其光催化活性。酯-105降解试验结果表明,初始p H为6.30(原溶液)、La掺杂比为0.50%、煅烧温度为450℃、光照为汞灯300 W、催化剂用量为0.3 g·L-1时,光催化活性最强,70 min后,酯-105降解率达99.59%;经验证,该催化剂重复使用4次后,酯-105降解率仍在99%以上,为La/TiO_2的工程实践应用提供了可能。     

纳米Fe2O3对甲基橙、亚甲基蓝和罗丹明B的光催化降解研究

以水热法制备的纳米Fe2O3作为光催化剂,在加入H2O2条件下,以高压汞灯为光源,对甲基橙(MO)、亚甲基蓝(MB)和罗丹明B(RhB)等染料进行光催化降解研究.实验表明:在相同光源与相等光强等条件下,当Fe2O3与H2O2的添加量一定时,罗丹明B最易降解,亚甲基蓝次之,而甲基橙的降解最慢,且更易受其他实验条件影响.     

Ba_2CaMO_6(M=Mo,W)的制备及其光催化降解酸性红B的性能

以硝酸钡、氧化钙和钼酸铵(钨酸铵)为原料,用溶胶凝胶法和溶胶凝胶-低温自燃烧的方法合成了双钙钛矿复合氧化物Ba2CaMO6(M=Mo,W),用X射线衍射和扫描电镜对制得的样品进行表征,并测试样品在400W高压汞灯照射下光催化降解酸性红B的活性。分别考察溶胶凝胶法合成样品时柠檬酸加入量对样品性能的影响和溶胶凝胶-低温自燃烧法合成样品时硝酸加入量对样品性能的影响。结果显示,溶胶凝胶法制得了形状规则的Ba2CaMO6(M=Mo,W)颗粒,其中的Ba2CaWO6具有光催化活性,且增加配合剂柠檬酸的用量可以提高Ba2CaWO6的光催化活性;溶胶凝胶-低温自燃烧法制得形状不规则的Ba2CaMO6(M=Mo,W)颗粒,一定范围内增加硝酸用量可以改善Ba2CaWO6的活性。紫外光照射下,Ba2CaMoO6没有显示出光催化降解酸性红B的活性。     

掺杂镨的纳米二氧化钛光催化降解2,4-二硝基苯酚的研究

以钛酸丁酯为原料,用溶胶-凝胶(Sol-gel)法制备了掺杂镨的纳米TiO2粉末.采用X光衍射仪对粉体的物相进行了表征.样品经500℃焙烧2h后,0.5%(摩尔分数,下同)Pr3+-TiO2纳米粉末为单一的锐钛型结构.通过粉体对2,4-二硝基苯酚的降解情况对其光催化活性进行了测试,结果表明与纯TiO2相比,Pr3+-TiO2的光催化活性有较大提高,当Pr3+的掺入量为0.5%时催化活性最高.以高压汞灯为光源,2,4-二硝基苯酚的初始浓度为50mg·L-1、催化剂0.5%Pr3+-TiO2投加量为1.0 g·L-1时,2,4-二硝基苯酚的光催化降解效果最好.     

掺杂钇的纳米二氧化钛光催化降解邻硝基苯酚的研究

以钛酸丁酯为原料,用溶胶-凝胶(so l-ge l)法制备了掺杂钇的纳米T iO2粉末。采用X光衍射仪对粉体的物相进行了表征。样品经500℃焙烧2h后,1.2%(摩尔分数)Y3+-T iO2纳米粉末为单一的锐钛型结构。通过粉体对邻硝基苯酚的降解情况对其光催化活性进行了测试,结果表明与纯T iO2相比,Y3+-T iO2的光催化活性有较大提高,当Y3+的掺入量为1.2%时催化活性最高。以高压汞灯为光源,邻硝基苯酚的初始浓度为50m g.L-1、催化剂1.2%(摩尔分数)-T iO2投加量为1.0 g.L-1时,邻硝基苯酚的光催化降解效果最好。     

可见光下掺N附Ag纳米TiO_2的光催化降解甲基橙

采用溶胶–凝胶法制备纯TiO_2和掺氮TiO_2纳米颗粒(N-TiO_2),然后通过光催化还原在其表面附Ag,得到表面附Ag的纳米TiO_2(即Ag/TiO_2)和掺N附Ag纳米TiO_2(即Ag/N-TiO_2),利用X射线衍射(XRD)、场发射扫描电镜(FE-SEM)、光致发光光谱仪(photoluminescence spectroscopy,PL)、X射线光电子能谱(XPS)以及紫外可见漫反射光谱分析(UV-VIS DRS)对TiO_2及其掺杂改性后的组成和结构、光吸收性能以及可见光下对甲基橙溶液的光催化活性等进行表征。结果表明,所有样品均为锐钛矿型,Ag/TiO_2的平均晶粒度为20.4 nm;N以替代型N-Ti-O、间隙型Ti-O-N(或氧化态Ti-O-N-O)的形式存在于晶格中,银以Ag0形式附着在TiO_2表面;N掺杂抑制TiO_2晶粒的生长,并抑制光生电子与空穴的复合,从而促进TiO_2对可见光的吸收;表面附Ag对TiO_2晶格没有明显影响,但在450~580 nm可见光区产生强烈的表面等离子吸收带并延长至近红外区。TiO_2及其掺杂改性后对甲基橙的光催化效果为Ag/N-TiO_2Ag/TiO_2N-TiO_2TiO_2(或Degussa P25),Ag/N-TiO_2在可见光下对甲基橙(p H=3)进行光催化降解,150 min时降解率达到95%。     

La掺杂TiO_2的制备及光催化处理石化二级出水的研究

采用溶胶-凝胶法制备了稀土La掺杂TiO_2纳米粉末,利用X射线衍射(XRD),紫外-可见漫反射光谱(UV-Vis DRS)、透射电镜(TEM)和荧光光谱(PL)等分析方法对所制备样品进行表征;以亚甲基蓝和石化二级出水作为降解对象,研究了La掺杂TiO_2样品的光催化性能。表征结果显示,本实验所制备的TiO_2样品均为锐钛矿晶型;稀土La掺杂可以使样品的晶粒尺寸由25 nm减小为15 nm;同时可改善样品的团聚现象;并可促进样品对可见光的吸收;此外还具有降低电子-空穴的复合,提高TiO_2量子效率的作用。光催化降解亚甲基蓝实验结果显示,当La掺杂含量为0. 50%时,样品的光催化性能最佳;优选0. 50%La-TiO2对石化二级出水进行光催化降解反应,结果显示光催化反应180min时,二级出水中的化学需氧量(COD)和UV254的降解率分别可达55%和70%以上;且经过3次回用后降解率未明显下降,说明本实验所制备的实验样品具有良好稳定的光催化性能,这为光催化深度降解石化二级出水工业应用提供了可能。     

用铁鳞制备纳米Fe_2O_3的研究

以铁鳞在盐酸溶液中的浸出液为原料,采用强迫水解法制备不同形貌纳米Fe2O3光催化剂,研究了铁鳞浸出液纯度对于纳米Fe2O3的微观形貌和光催化性能的影响。结果表明:8g铁鳞与150ml物质的量浓度为3mol/L的盐酸溶液100℃回流反应2h,铁鳞的浸出率达到93%左右,且浸出液纯度较高;浸出液中的杂质离子改变了纳米Fe2O3的微观形貌;以铁鳞浸出液为原料制备出的纳米Fe2O3可见光光催化性能较好,光降解甲基蓝溶液50min后,其降解率可达82%左右。     

A stable and efficient La-doped MIL-53(Al)/ZnO photocatalyst for sulfamethazine degradation

Photocatalytic technology can solve various environmental pollution problems, especially antibiotic pollution. A novel La-doped MIL-53(Al)/ZnO composite material was successfully synthesized by a combination of hydrothermal method and calcination, showing high photocatalytic degradation percent of sulfamethazine (SMT). The 2 mol% La MIL-53(Al)/ZnO photocatalyst shows the highest degradation efficiency toward SMT (92%) within 120 min, which is 4.1 times higher than pure ZnO (increased from 18% to 92%). In addition, the degradation analysis of SMT by high performance liquid chromatography proves that the products are CO₂ and H₂O. The improved photocatalytic activity is mostly caused by the following factors. (1) Doping La ions can decrease the band gap of ZnO, enhance light response, and effectively enhance the separation rate of photo-generated holes and electrons. (2) MIL-53(Al) can adsorb SMT and promote the separation of electron. This work shows that the synthesized La-doped MIL-53(Al)/ZnO photocatalyst is expected to be used as a green and effective method for treatment of environment water pollution.     

金属离子掺杂对离子液辅助制备纳米TiO_2性能的影响

以过渡金属(Cr、Fe、Ni和Zn)掺杂为手段,以溶胶凝胶为制备方法,以离子液2—羟基咪唑甲酸盐为微观结构调控试剂,制备了TiO_2纳米粒子。将样品备好后,在500℃的条件下进行煅烧处理,用BET、XRD、DRS等手段进行结构表征,以酸性蓝92为模拟污染物对其光催化性能进行测定。研究结果表明,经过渡金属掺杂后的TiO_2纳米颗粒比纯TiO_2具有更高的比表面积和更小的粒径尺寸。过渡金属的掺杂使TiO_2的吸收光谱向可见光的方向移动。在紫外灯照射下,水溶液中酸性蓝92的光降解结果为:过渡金属离子的存在使TiO_2纳米颗粒的光催化活性得到了明显增强。     

Lanthanum and boron co-doped BiVO4 with enhanced visible light photocatalytic activity for degradation of methyl orange

BiVO4 photocatalysts co-doped with La and B were prepared by sol-gel method using citric acid as chelate.The samples were characterized by X-ray photoelectron spectroscopy(XPS),X-ray diffraction(XRD),scanning electron microscopy(SEM),Brumauer-Emmett-Teller(BET),UV-Vis diffuse reflectance spectra(DRS) and the photocatalytic activity was investigated by photocatalytic degradation of methyl orange(MO).The results showed that boron and lanthanum ions incorporated into the lattice of BiVO4,and co-doping led to more surface oxygen vacancies,high specific surface areas,small crystallite size,narrow band gap and intense light absorbance in visible region.And the doped La(III) ions could help the separation of photogenerated electrons.Compared with BiVO4 and B-BiVO4,the photocatalytic activity of La-B co-doped BiVO4 was remarkably improved due to the synergistic effects of the co-doped ions.The degradation rate of MO in 60 min was 98.4% when La doping content was 0.05 mol.%,which was much higher than that of pure BiVO4(20%) and B-BiVO4(37%).     

Preparation and photocatalytic activity of Fe3O4@SiO2@ZnO:La

In this study, Fe₃O₄@SiO₂@ZnO:La microspheres were successfully prepared. The microspheres have the advantages of both ZnO doped with La and the Fe₃O₄@SiO₂ structure such that the former improves the photocatalytic activity of ZnO and the latter can be reused. The X-ray diffraction (XRD), a field emission scanning electron microscope (SEM), a field emission transmission electron microscope (TEM), X-ray photoelectron spectroscopy (XPS), and a vibrating sample magnetometer (VSM) were used to characterize Fe₃O₄@SiO₂@ZnO:La microspheres. Methyl orange was used as the model molecule to study the effect of the Zn²⁺ concentration and the doping amount of La on the photocatalytic activity of Fe₃O₄@SiO₂@ZnO:La microspheres. Results show that in the synthesis of Fe₃O₄@SiO₂@ZnO:La microspheres, photocatalytic activity of the microspheres is enhanced first and weakened later with the increase of Zn²⁺ concentration. In the La doping process, the photocatalytic activity of Fe₃O₄@SiO₂@ZnO:La microspheres is enhanced with the increase in the La doping amount. The magnetic photocatalysts not only have high photocatalytic activity, but also can be reused. After being reused five times, the photocatalyst's degradation rate of methyl orange is still as high as 81%, which shows that magnetic photocatalysts have prospective wider applications in photocatalytic degradation of dye wastewater.     

Photocatalytic Destruction of Nitrogen Monoxide over La^3＋ and N Co-doped SrTiO3 Powders under Visible Light Irradiation

Lanthanun, and nitrogen co-doped SrTi03 was prepared by a mechanochemical reaction using SrTi03, urea and la203 as the raw materials. The samples were characterized by X-ray diffraction, X-ray photoelectron spectrometer, trans-mission electron microscopy, and nitrogen adsorption-desorption isotherm measurements, lanthanum doping could increase the doping content of nitrogen in the sample. The sample prepared with 0.2 mol% La203, 22 mol% urea and 77.8 mol % SrTi03 by mechanochemical reaction, which has nearly the same nitrogen and lanthanum doping fractions, exhibited high photocatalytic activities. Under the irradiation of light with wavelength larger than 400, and 290 nm, the photocatalytic activity of nitrogen and lanthanum co-doped SrTi03 were 2.6 and 2 times greater than that of pure SrTi03.     

Preparation and Photocatalytic Activity of Nanocrystalline GdFeO3

Photocatalytic reactions at semiconductor particleshave been the focus of numerous investigations in re-cent years ,since their applicationresults inthe quan-titative degradation of a large number of chemical con-taminants . Of many semiconductor oxides , TiO2hasbeen provento be the benchmark photocatalyst for ef-fective degradation of organic pollutants ,pri marily be-cause of its optical and electronic properties ,lowcost ,chemical stability and non-toxicity .However ,sinceitsband-gapis larg…     

Photocatalytic Activity of Nanosized TiO2 Enhanced by co-doping with Fe3+ and Nd3+ Ions

In this study, nanosized TiO2 co-doped with Fe3 and Nd3 ions was synthesized via a sol-gel method. The metallic ion doped TiO2 was thoroughly characterized with XRD and UV-vis, and the photocatalytic activity was evaluated by degrading methylene blue (MB) solution. The results indicated that TiO2 crystalline size was reduced and phase transformation of anatase to rutile was suppressed as the content of doped Nd3 ion increased in the co-doped TiO2. The UV-vis spectra of co-doped TiO2 seemed to simply overlay two spectra of single metal doped TiO2, and had significantly increased absorbance in the ranges of 400~500 nm, 565~600 nm and 730~765 nm as compared to pure TiO2. The photocatalytic activity of co-doped TiO2 was obviously enhanced, and raised about 30% compared to that of pure TiO2 as doped Nd3 content was 0.15% and Fe3 content was 0.05%, respectively. The enhanced catalytic activity was attributed to a synergistic effect of two doped ions, where doped Fe3 ion inhibited the recombination of photogenerated electron and hole, and Nd3 ion brought more surface carboxyl to promote the degradation reaction.     

低量La3+掺杂WO3的表征及其光解水催化性能的研究

采用低热固相反应法制备了低量La3+(0.05%)掺杂的WO3催化材料,采用XRD、XPS和DRS对样品进行了表征和分析,考察了样品光催化分解水制氧的活性。结果表明,0.05%La3+掺杂可使WO3光谱响应范围向可见光区拓展。XPS分析表明,La3+掺杂可导致粉体表面晶格氧的增加。在可见光辐射下光催化分解水制氧的试验中,0.05%La3+掺杂WO3的光催化析氧速率高达177μmol/(L.h),是未掺杂WO3的1.8倍。     

La-Ce共掺杂制备La3+-Ce3+/ZnO及其对亚甲基蓝的光催化降解

采用溶胶凝胶法制备了La-Ce共掺杂的La3+-Ce3+/ZnO光催化剂,同时用同种方法制备了ZnO、La3+/ZnO和Ce3+/ZnO以作对比.通过X射线衍射仪、透射电镜、紫外可见分光光度计,比表面及孔隙度分析仪等对制备的光催化剂进行了表征.以亚甲基蓝为模型污染物对所制备的光催化剂的光催化特性进行了评价.结果表明,所制备的La3+-Ce3+/ZnO光催化剂基本呈长方柱状,尺寸平均为57.3 nm,La-Ce共掺杂提高了ZnO的结晶度,促进了晶粒的长大.根据光催化实验结果,La-Ce共掺杂能够显著提高ZnO的光催化活性.在光催化降解500 mL的10 mg·L-1亚甲基蓝实验中,La3+-Ce3+/ZnO光催化剂对亚甲基蓝的降解率达93.7%,比纯ZnO、La3+-ZnO和Ce3+-ZnO分别提高了21.4%、19.2%和9.3%.