La掺杂Bi2O3的制备、表征与可见光催化活性

采用浸渍法制备了La掺杂Bi2O3(La-Bi2O3)光催化剂,利用X射线荧光光谱(XRF)、X射线衍射(XRD)、扫描电子显微镜(SEM)、傅立叶变换红外光谱(FT-IR)、X射线光电子能谱(XPS)、紫外-可见吸收光谱(UV-Vis)和光致发光谱(PL)等分析测试手段对样品的La掺杂量、晶体结构和光谱特征等进行了表征,并以2,4-二氯苯酚(2,4-DCP)水溶液的降解作为探针反应,考察了样品的可见光催化性能.结果表明,适量的La掺杂能有效抑制Bi2O3由四方相向单斜相转变,并将光吸收范围拓展到550 nm以上.掺杂的La可取代Bi2O3晶格中部分Bi,形成Bi—O—La键,并生成了少量镧铋复合氧化物(La0.176Bi0.824O1.5),它们的存在能有效抑制光生电子-空穴对的复合,从而提高光催化量子产率.可见光照射下2,4-DCP的光催化降解实验表明,La-Bi2O3具有良好的可见光催化性能,并且当La的掺杂量为3%(摩尔分数)时,催化剂的可见光催化效率最高.     

Bi2Ti2O7/TiO2复合纤维：原位水热合成及光催化性能

采用静电纺丝技术制备的TiO2纤维作为模板和反应物,通过原位水热合成了具有异质结构的Bi2Ti2O7/TiO2复合纤维。利用X射线衍射(XRD)、扫描电镜(SEM)、能量散射光谱(EDS)、高分辨透射电镜(HRTEM)和紫外可见吸收光谱(UV-Vis)等分析测试手段对样品的结构和形貌进行表征。以罗丹明B为模拟有机污染物进行光催化降解实验。结果表明:花状Bi2Ti2O7纳米结构均匀地生长在TiO2纤维上,制备了Bi2Ti2O7与TiO2相复合的光催化材料,其光谱响应范围拓宽至可见光区,与纯TiO2纤维相比可见光催化活性显著提高,且易于分离、回收和循环使用。初步探讨了Bi2Ti2O7/TiO2异质结的生长机制和光催化活性提高机理。     

Bi2O3 /TiO2复合纳米颗粒的可见光光催化性能

采用溶胶与水热相结合的方法合成了具有可见光光催化活性的复合纳米颗粒Bi2O3/TiO2,并对其进行了X射线衍射、透射电镜、X射线光电子能谱、紫外-可见漫反射谱、红外光谱、低温N2吸附脱附及电子顺磁共振分析。结果表明,复合少量的氧化铋可显著抑制TiO2由锐钛矿到金红石的相转移过程,并将光吸收范围扩展到可见光区。可见光照射下(λ>420 nm),利用电子顺磁共振技术检测到明显的羟基自由基(.OH)信号。铋的最佳掺杂量为Bi/Ti质量比2.0%,适量铋的掺入能显著改善锐钛矿TiO2的结晶度,抑制光生电子-空穴对的复合,提高光催化量子效率。通过可见光照射下,4-氯酚的降解实验测试Bi2O3/TiO2复合纳米颗粒的可见光光催化活性。同时,利用气-质联用仪对4-氯酚降解过程的中间产物进行了测定,并提出可见光照射下的Bi2O3光敏化机理。     

原位溶解-沉积法制备高可见光活性BiOI/Bi2O3光催化剂

以Bi2O3为前驱体,通过原位溶解-沉积法在KI溶液中制备了BiOI/Bi2O3光催化剂。用X射线衍射(XRD)、扫描电子显微镜(SEM)和紫外-可见漫反射光谱(UV-Vis DRS)等对样品进行了表征。结果表明Bi2O3球形颗粒紧密地贴在BiOI片上。随着KI溶液pH值的降低,Bi2O3逐渐转变为BiOI,且样品的吸收带边逐渐红移。在可见光(λ≥420 nm)下降解甲基橙,在pH=3下制备的BiOI/Bi2O3的活性最强,其原因是BiOI/Bi2O3 p-n异质结促进了光生载流子的分离。     

Ce掺杂Bi2MoO6/TiO2纳米纤维异质结的制备及可见光催化性能

以静电纺丝技术制备的TiO_2纳米纤维为基质,通过溶剂热法制备了异质结型稀土Ce掺杂Bi_2MoO_6/TiO_2复合纳米纤维。利用X射线衍射(XRD)、扫描电子显微镜(SEM)、X射线光电子能谱(XPS)、透射电镜(TEM)、紫外-可见漫反射光谱(UV-Vis DRS)以及荧光光谱(PL)等分析测试手段对样品的物相、形貌和光学性能等进行表征。以罗丹明B为模拟有机污染物,研究了样品的可见光催化性能。结果表明:在稀土掺杂样品中,Ce离子进入Bi_2MoO_6晶格,部分取代Bi3+,导致晶胞膨胀,晶格畸变,形成缺陷;与TiO_2复合形成异质结,有利于光生电荷的产生、转移和有效分离,从而提高TiO_2纳米纤维的光催化活性。可见光照射180 min,罗丹明B的降解率达到95.1%。经5次循环光催化降解活性基本不变,样品具有良好的光催化稳定性。     

Bi/TiO2复合纳米纤维制备及可见光催化性能

以电纺TiO₂纳米纤维为基质,EDTA为鳌合剂和吸附剂,采用溶剂热法制备Bi/TiO₂复合纳米纤维光催化材料,利用X射线粉末衍射（XRD）、扫描电镜（SEM）、X射线能量色散谱（EDS）、透射电镜（TEM）、紫外-可见漫反射光谱（UV-Vis DRS）和荧光光谱（PL）等分析测试手段对样品的物相、形貌和光学性能等进行表征,以罗丹明B（RhB）为模拟有机污染物,考察了样品的光催化性能。结果表明：EDTA在复合纳米纤维的合成过程中起到关键作用,通过改变EDTA的用量可以有效控制纤维表面构筑单质Bi纳米球的大小和覆盖密度。所制备的复合纳米纤维具有良好的可见光催化活性和稳定性,当单质Bi的负载量为65%时光催化活性最强,可见光照射180 min,RhB的降解率达到96.40%,循环使用5次降解率仍保持在91%以上。     

Bi4(Ti1/3Sn2/3)3O12掺杂BaTiO3基X8R陶瓷微观结构与介电性能

研究了Bi4(Ti1/3Sn2/3)3O12掺杂对钛酸钡基陶瓷微观结构和介电性能影响。结果表明,掺杂Bi4(Ti1/3Sn2/3)3O12后钛酸钡基陶瓷晶粒明显长大,同时烧结温度可由1 280℃降低至1 180℃。系统的介电性能和Bi4(Ti1/3Sn2/3)3O12的掺杂量有密切关系。当Bi4(Ti1/3Sn2/3)3O12的掺杂量从0.5mol%增加到2mol%,体系的居里峰被明显压低和展宽,当掺杂量为2mol%时居里峰变得不明显。当Bi4(Ti1/3Sn2/3)3O12的掺杂量从0.5mol%增加到2mol%,系统的居里温度由131℃升高至139℃。当Bi4(Ti1/3Sn2/3)3O12的掺杂量为1mol%时,钛酸钡基陶瓷介电常数为1 930,介电常数温度变化率为5%(-55℃),13%(134℃),-8%(150℃),满足X8R标准。     

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.     

浓度梯度分布的镍和氮共掺杂TiO2光催化剂的制备和表征

以TiCl4为钛前驱体, 氨水和氯化镍为掺杂离子给体, 采用沉淀和层层浸渍相结合的方法制备了氮、镍共掺杂TiO2光催化剂. 采用X射线衍射(XRD)、氮气吸附-脱附、X射线光电子能谱(XPS)、紫外-可见漫反射吸收光谱(UV-Vis)等现代表征方法对催化剂的晶体结构、微结构、掺杂基团和光谱性质进行了表征. XRD和氮吸附-脱附分析结果表明, 氮、镍共掺杂TiO2为单一锐钛矿相, 具有介孔结构. XPS谱证实掺杂的氮和镍分别以NOx和Ni2O3及NiO的形式存在, 且镍在共掺杂表面的浓度高于体相中的浓度, 在扩散方向上存在浓度梯度分布. 4-氯酚的降解实验结果表明, 浓度梯度分布镍和氮共掺杂TiO2的紫外光-可见光催化活性均高于均相共掺杂TiO2、单掺杂和未掺杂TiO2的催化活性. 其原因是掺杂的氮以NOx形式存在, 使催化剂的感光范围拓展至可见光区; 而掺杂的镍维持了半导体体系的电荷平衡, 有效抑制了Ti3+的产生. 同时掺杂的镍在催化剂中存在浓度梯度分布, 减少了光生电子和空穴的复合几率, 提高了催化剂的光催化活性.     

Bi/TiO_2复合纳米纤维制备及可见光催化性能

以电纺TiO_2纳米纤维为基质,EDTA为鳌合剂和吸附剂,采用溶剂热法制备Bi/TiO_2复合纳米纤维光催化材料,利用X射线粉末衍射(XRD)、扫描电镜(SEM)、X射线能量色散谱(EDS)、透射电镜(TEM)、紫外-可见漫反射光谱(UV-Vis DRS)和荧光光谱(PL)等分析测试手段对样品的物相、形貌和光学性能等进行表征,以罗丹明B(Rh B)为模拟有机污染物,考察了样品的光催化性能。结果表明:EDTA在复合纳米纤维的合成过程中起到关键作用,通过改变EDTA的用量可以有效控制纤维表面构筑单质Bi纳米球的大小和覆盖密度。所制备的复合纳米纤维具有良好的可见光催化活性和稳定性,当单质Bi的负载量为65%时光催化活性最强,可见光照射180 min,RhB的降解率达到96.40%,循环使用5次降解率仍保持在91%以上。     

Self-doped Br in Bi5O7Br ultrathin nanotubes: Efficient photocatalytic NO purification and mechanism investigation

Bismuth-rich Bi₅O₇Br is a promising photocatalyst for pollutant removal owing to its stability and appropriate band structure in comparison with bismuth oxybromide.However,bulk-phase Bi₅O₇Br suffers from poor light absorption and high charge recombination rates resulting in poor activity.Elemental doping is a powerful strategy to enhance photocatalytic activity.In this study,we prepared a series of Br autodoped ultrathin Bi₅O₇Br n...     

Co doped ZnO nanowires as visible light photocatalysts

High aspect ratio cobalt doped ZnO nanowires showing strong photocatalytic activity and moderate ferromagnetic behaviour were successfully synthesized using a solvothermal method and characterized by scanning electron microscopy (SEM), X-ray powder diffraction (XRD), X-ray photoelectron spectroscopy (XPS), X-ray absorption spectroscopy (XAS), vibrating sample magnetometry (VSM) and UV–visible absorption spectroscopy. The photocatalytic activities evaluated for visible light driven degradation of an aqueous methylene orange (MO) solution were higher than for Co doped ZnO nanoparticles at the same doping level and synthesized by the same synthesis route. The rate constant for MO visible light photocatalytic degradation was 1.9·10⁻³ min⁻¹ in case of nanoparticles and 4.2·10⁻³ min⁻¹ in case of nanowires. We observe strongly enhanced visible light photocatalytic activity for moderate Co doping levels, with an optimum at a composition of Zn_0.95Co_0.05O. The enhanced photocatalytic activities of Co doped ZnO nanowires were attributed to the combined effects of enhanced visible light absorption at the Co sites in ZnO nanowires, and improved separation efficiency of photogenerated charge carriers at optimal Co doping.     

Structural,optical and photocatalytic activity of cerium doped zinc aluminate

Zinc aluminate and cerium-doped zinc aluminate nanoparticles are synthesised by co-precipitation method. Ammonium hydroxide is used as a precipitating agent. The synthesised compounds are characterised by powder X-ray diffraction (XRD), Fourier transform Infrared spectroscopy (FT-IR), Ultraviolet diffuse reflectance spectroscopy (UV-DRS), Thermogravimetric analysis (TGA), Scanning electron microscopy (SEM) and Surface area measurements. The photocatalytic activity of zinc aluminate and cerium doped zinc aluminate nanoparticles are studied under the UV light and visible light taking methylene blue as a model pollutant. The amount of catalyst, concentration of dye solution and time are optimised under UV-light. Degradation of methylene blue under the UV-light is found to be 99% in 20 min with 10 mg of cerium doped catalyst. Compared to visible light degradation, the degradation of dye under UV-light is higher. Cerium doping in zinc aluminate (ZnAl₂O₄:Ce³⁺) increased the photocatalytic activity of zinc aluminate.     

Enhanced photocatalytic activities of ZnO thin films: a comparative study of hybrid semiconductor nanomaterials

Nanostructure single ZnO, SnO₂, In₂O₃ and composite ZnO/SnO₂, ZnO/In₂O₃ and ZnO/SnO₂/In₂O₃ films were prepared using sol?Cgel method. The obtained composite films were characterized with X-ray diffraction (XRD), scanning electron microscopy (SEM), and UV?CVis spectroscopy. The photocatalytic activities of composite films were investigated using phenol (P), 2,4-dichlorophenol (2,4-DCP), 4-chlorophenol (4-CP) and 4-aminophenol (4-AP) as a model organic compounds under UV light irradiation. Hybrid semiconductor thin films showed a higher photocatalytic activity than single component ZnO, SnO₂ and In₂O₃ films. The substituted phenols degrade faster than phenol. The ease of degradation of phenols is different for each catalyst and the order of catalytic efficiency is also different for each phenol. The use of multiple components offered a higher control of their properties by varying the composition of the materials and related parameters such as morphology and interface. It was also found that the photocatalytic degradation of phenolic compounds on the composite films and single films followed pseudo-first order kinetics.     

Synthesis and Modification of Zn‐doped TiO2 Nanoparticles for the Photocatalytic Degradation of Tetracycline

The synthesis of Zn‐doped TiO₂ nanoparticles by solgel method was investigated in this study, as well as its modification by H₂O₂. The catalyst was characterized by transmission electron microscopy, X‐ray diffraction, Brunauer–Emmett–Teller, UV–visible reflectance spectra and X‐ray photoelectron spectroscopy (XPS). The results indicated that doping Zn into TiO₂ nanoparticles could inhibit the transformation from anatase phase to rutile phase. Zn existed as the second valence oxidation state in the Zn‐doped TiO₂. Zn‐doped TiO₂ that was synthesized by 5% Zn doping at 450°C exhibited the best photocatalytic activity. Then, the H₂O₂ modification further enhanced the photocatalytic activity. Zn doping and H₂O₂ modifying narrowed the band gap and efficiently increased the optical absorption in visible region. The optimal degradation rate of tetracycline by Zn‐doped TiO₂ and H₂O₂ modified Zn‐doped TiO₂ was 85.27% and 88.14%. Peroxide groups were detected in XPS analysis of H₂O₂ modified Zn‐doped TiO₂, favoring the adsorption of visible light. Furthermore, Zn‐doped TiO₂ modified by H₂O₂ had relatively good reusability, exhibiting a potential practical application for tetracycline's photocatalytic degradation.     

Chemical deposition of zirconium doped tin silicate ion-exchanger and its characterization

Doping of inorganic ion-exchange material tin silicate with zirconium ion by sol-gel technique was conducted for the production of a novel ion-exchanger. Undoped and doped tin silicate has been characterized by elemental analysis (X-ray fluorescence), Fourier transform infrared spectroscopy (FT-IR), thermal analysis and X-ray diffraction studies. The structures of two ion-exchangers were identified and the empirical formulas found as SnSi₂O₆·6H₂O and SnZr₄Si₄O₁₂·16H₂O for tin silicate and zirconium doped tin silicate, respectively. The effect of zirconium ion concentration of the doped tin silicate on the crystalline size and strain of tin silicate was investigated. The probable structure of both materials was assessed by the ChemDraw Ultra program. Finally, application of these materials for the treatment of radionuclides in terms of capacity measurements was investigated.     

Direct synthesis of Nd3+ doped mesoporous TiO2 and investigation of its photocatalytic performance

Nd³⁺ doped mesoporous TiO₂ samples with different molar ratio of Nd/Ti were synthesized by a sol?Cgel method. The textural and optical properties of the samples were systematical characterized by X-ray diffraction, transmission electron microscopy, N₂ adsorption?Cdesorption isotherms, Fourier transform infrared spectroscopy and UV?CVisible absorbance spectroscopy. It was revealed that Nd³⁺ doping inhibited the phase transformation from anatase to rutile after calcination, and the mesoporous structure of doped samples was still retained with the increase of Nd/Ti molar ratio. The surface area of the samples varied from 137 to 210 m²g^?1 and the average pore size of them ranged between 5.7 and 8.2?nm. The photocatalytic activities of all the samples were evaluated by degradation methyl orange (MO) in aqueous solution as a model reaction under UV light irradiation. The results showed that the doped samples demonstrated a higher photocatalytic activity than the mesoporous TiO₂, and the 3?mol% Nd³⁺ doped mesoporous TiO₂ exhibited the best photocatalytic performance. Meanwhile, a promotion effect of the H₂O₂ added was verified in the degradation of MO.     

Comparison of optical and structural properties of nanostructure TiO2 thin film doped by Sn and Nb

The thin films of TiO₂ doped by Sn or Nb were prepared by sol–gel method under process control. The effects of Sn and Nb doping on the structural, optical and photo-catalytic properties of applied thin films have been studied by X-ray diffraction (XRD) high resolution transmission electron microscopy and UV–Vis absorption spectroscopy. Surface chemical state of thin films was examined by atomic X-ray photoelectron spectroscopy. XRD results suggest that adding impurities has a great effect on the crystallinity and particle size of TiO₂. Titania rutile phase formation in thin film was promoted by Sn⁴⁺ addition but was inhibited by Nb⁵⁺ doping. The activity of the photocatalyst was evaluated by photocatalytic degradation kinetics of aqueous methylene blue under UV and Visible radiation. The results show that the photocatalytic activity of the Sn-doped TiO₂ thin film have a larger degradation efficiency than Nb-doped TiO₂ under visible light, but under UV light photocatalytic activity of the Nb-doped TiO₂ thin film is better.     

掺杂纳米TiO2光催化性能的研究

利用浸渍法分别制备了Cr、Mn、Fe、Co、Ni、Cu六种过渡金属离子掺杂改性的二氧化钛光催化剂，以乙酸水溶液的光催化氧化反应和二氧化碳还原反应为探针,评价了掺杂催化剂的光催化性能.借助光电子能谱（XPS）、X射线衍射分析（XRD）等手段对掺杂催化剂进行了表征.研究结果表明，经过渡金属离子掺杂后，光催化性能均有不同程度的改善，改善程度按Cr、Co、Ni、Fe、Mn、Cu递增.掺杂后催化剂表面吸附氧的活泼性、金属离子的价态及得电子能力上的差异决定了不同离子掺杂纳米二氧化钛光催化性能的差异.