掺Fe3+A-TiO2粉末的制备及其可见光催化降解碱性品红

以硫酸钛为原料用水热法制备了掺Fe3+TiO2粉末,用SEM测定了样品的形貌和晶型,研究了以自制的掺Fe3+ A-TiO2对碱性品红溶液的光催化降解作用.结果表明:所制备的TiO2为锐铁矿型TiO2(A-TiO2).可见光照射下,用自制的掺Fe3+A-TiO2降解碱性品红溶液的最佳条件是:2mg·L-1的碱性品红溶液中...     

紫外光下锐钛矿型二氧化钛对甲基红的催化降解

研究了在紫外光(λ=365nm)照射下,以自制的掺铁锐钛矿型二氧化钛对甲基红的催化降解效果,分析了甲基红初始浓度、二氧化钛的用量、掺铁量、光照时间和溶液初始pH值等因素的影响.结果表明:在15mg/L的甲基红溶液(pH=5)中,加入0.7 g/L自制二氧化钛(掺铁量1％、摩尔分数),室温下紫外光照反应30min,甲基红的降解率达到99.21％.     

H_3PW_(12)O_(40)/La-N-TiO_2复合催化剂可见光下光催化降解吡虫啉研究(英文)

制备出H3PW12O40/La-N-TiO2催化剂并采用红外光谱,N2吸附-脱附分析,透射电镜和紫外漫反射进行结构表征。红外光谱检测表明,复合催化剂中H3PW12O40保留了Keggin结构;掺杂La-N之后,复合催化剂的BET比表面积是母体TiO2的两倍;透射电镜检测表明,催化剂由相对均匀的球形颗粒组成,分散性良好;紫外漫反射检测表明,掺杂La和N元素后所制备的复合催化剂对可将光的光响应性能明显提高。对吡虫啉的光催化实验表明,所制备的不同负载量催化剂中30%H3PW12O40/0.3%La-1.0%N-TiO2具有最好的光催化活性(≥400nm),光照3h后吡虫啉降解率为91.57%,光照6h后吡虫啉降解率达98.89%,基本上完全降解。     

SrFeO3-x可见光下降解亚甲基蓝的光催化性能研究

采用水热及柠檬酸法相结合的方法,制备了钙钛矿型复合氧化物SrFeO3-x(0＜x＜0.5)光催化剂.用X射线衍射(XRD)、紫外可见漫反射光谱(DRS-UV-Vis)、表面光电压谱(SPS)和场致表面光电压谱(EFISPS)表征制备的SrFeO3-x.以亚甲基蓝(MB)为模拟污染物,在可见光(λ≥430nm)照射下,首次考察了钙钛矿型复合氧化物SrFeO3-x的光催化性能,得到了较好的结果.     

TiO2光催化降解废水中的甲硝唑

以低浓度甲硝唑为模型污染物,研究TiO2光催化降解甲硝唑废水.以5.0mL 60tmol/L的甲硝唑溶液为降解目标,考察了Cu2+浓度、溶液pH值、光照时间、TiO2用量等对甲硝唑降解率的影响.实验表明,当初始浓度为60μμmol/L的甲硝唑溶液、500mg/L H2O2溶液、225μmol/L的Cu2+溶液均取5.0mL参加反应,用硫酸调节pH约为3.0,当TiO2用量为4.12mg、光照反应时间为75min时,平均降解效果可达91.87％.     

S、Cr共掺杂TiO2纳米材料的固相合成及其可见光降解性能

采用固相反应法分别合成了铬掺杂二氧化钛(Cr-TiO2)及硫和铬共掺杂二氧化钛(S-Cr-TiO2)纳米材料.并用XRD、SEM、UV-Vis、XPS、N2吸附等技术对材料进行了物相结构表征,同时研究了材料对水溶苯胺蓝的可见光降解性能.结果表明,在S-Cr-TiO2纳米材料中,硫以阳离子S6+进入二氧化钛晶格或晶格间隙...     

可见光响应SO2－4／Ce-TiO2的光谱特征及催化性能

采用溶胶‐凝胶法制备了Ce掺杂 T iO2,经 H2 SO4处理得到酸化Ce掺杂 T iO2。利用X射线衍射（XRD）、傅里叶变换红外光谱（FTIR）、吡啶吸附红外光谱（Py‐FTIR）、紫外‐可见光漫反射光谱（UV‐Vis）及X射线光电子能谱（XPS）技术对样品的性质进行了表征,以罗丹明B（RhB）在样品上的可见光催化降解为模型反应,评价了所制备样品的光催化性能。XRD测试结果表明,铈掺杂使 TiO2产生晶格缺陷、粒径减小,有利于光生电荷的转移,继而提高催化剂的活性;FTIR谱图说明SO2－4以桥式双齿配位吸附形式存在;Py‐FTIR谱图显示,酸化铈掺杂TiO2样品表面同时存在Br?nsted和Lewis酸位,但以Lewis酸为主。Lewis酸中心的缺电子性质有利于样品表面的光生电子与光生空穴分离,从而改善催化剂的活性;UV‐Vis结果表明,Ce掺杂减小了TiO2的带隙能,引入的杂能级能够捕获导带上的光生电子和价带上的光生空穴,降低光生电子‐空穴对的复合几率;同时还可以使能量较小的光子激发杂能级上捕获的电子,拓宽光响应范围;XPS分析表明SO2－4／Ce‐TiO2样品上同时存在Ce3＋／Ce4＋的混合价态,Ce3＋／Ce4＋氧化‐还原转换有助于TiO2受光激发后产生的光生电子和空穴的分离,从而提高光量子效率。酸化Ce掺杂TiO2对RhB的可见光催化降解反应有很好的活性,实验结果证明,H2 SO4酸化和Ce掺杂的协同作用改善了样品的可见光响应,促进了其可见光催化反应活性。     

氮掺杂TiO2的冲击合成及可见光催化活性研究

 冲击相变及冲击诱导化学反应可导致材料的物理、化学性能发生显著改变。采用炸药爆轰驱动飞片高速碰撞产生冲击波的方法,对富氮掺杂物双氰胺（C₂N₄H₄）与P25 TiO₂或偏钛酸（H₂TiO₃）的粉末混合物进行冲击加载,对回收产物进行X射线粉末衍射、透射电子显微镜、X光电子能谱、比表面积及紫外-可见漫反射光谱表征,通过亚甲基蓝和罗丹明B评价了回收产物的可见光催化降解活性。结果表明：以P25 TiO₂为原料的冲击氮掺杂浓度可达8.88%,掺杂样品具有明显的可见光吸收,能带宽度减小到1.75 eV,样品中形成了少量Srilankite高压相;而以偏钛酸为原料的冲击氮掺杂浓度为3%～4%,能带宽度变化较小,但是由于其独特的冲击脱水膨胀机理,比表面积剧增。冲击氮掺杂样品对亚甲基蓝和罗丹明B染料有较好的吸附和可见光催化降解作用,其中高飞片速度处理的样品有更高的光催化降解活性。     

AgNbO3/石墨烯复合材料的合成及其可见光催化甲基橙降解活性

采用固相法合成AgNbO₃/石墨烯复合纳米材料,利用透射电子显微镜(TEM)及紫外-可见漫反射光谱(UV-Vis)对样品的形貌及光学性质进行了表征。研究发现,AgNbO₃与石墨烯复合后,带隙能明显降低,吸收光波长范围增大。以甲基橙溶液的降解为光催化模型反应评价了AgNbO₃/石墨烯复合纳米材料的可见光催化性能。结果表明:与纯AgNbO₃相比,AgNbO₃/石墨烯复合纳米材料对甲基橙的可见光催化性能明显增强。实验条件下,经300 ℃煅烧的AgNbO₃/石墨烯(2:1)复合纳米材料表现出最优的催化性能,它对甲基橙的可见光催化脱色速率系数约为纯AgNbO₃的10倍。光催化降解机理研究表明,促使甲基橙降解脱色的主要活性物种为·O₂^- 和 h⁺。     

ZnO/BiOBr复合材料制备及可见光催化降解RhB性能研究

通过溶剂热法制备不同ZnO和BiOBr摩尔配比的ZnO/BiOBr复合光催化剂。ZnO与BiOBr摩尔比为1∶2时,ZnO/BiOBr复合材料光催化降解罗丹明B的性能最好,可见光照120 min,罗丹明B(20 mg/L)去除率达98.89%,降解速率常数为0.040 50 min^-1,是纯BiOBr的4倍。紫外-可见漫反射和荧光光谱分析显示较纯ZnO,ZnO/BiOBr(1∶2)吸收带红移,光子利用率提高,且光生电子-空穴复合机率降低。通过电子顺磁共振波谱仪和半导体能带理论对降解机理进行分析,结果显示降解过程主要通过·O₂^-、·OH自由基的氧化作用,ZnO与BiOBr之间形成界面电场,降低了电子-空穴的复合机会。     

掺Fe(Ⅲ)的A-TiO_2的水热法制备、表征及其光催化活性分析

一定条件下用水热法制备了的掺Fe(Ⅲ)的TiO2晶体,XRD分析结果表明它是锐钛矿型Fe(Ⅲ)的TiO2(A-TiO2).研究了以自制的掺Fe(Ⅲ)的A-TiO2为光催化剂对罗丹明B溶液的降解性能.结果表明,在5 mg/L的罗丹明B溶液中,加入0.1650 g自制的掺Fe(Ⅲ)的5%的A-TiO2,用硝酸调节溶液PH=5后,可见光照射下,43℃恒温磁力快速搅拌反应6 h,罗丹明B降解率为76.5%;同样条件下经254nm紫外光照6 h,降解率达到95.7%.     

掺铁TiO2纳米薄膜的制备及光催化性能研究

采用溶胶-凝胶提拉法制备了掺铁改性TiO2纳米材料镀膜玻璃,研究了掺铁、PEG用量、镀膜层数等因素对TiO2纳米膜透光率和光催化降解性的影响,并对相关机理进行了探讨。研究发现,掺铁能提升TiO2纳米膜的光催化活性,催化降解速率为不掺铁时的1．38倍;溶胶前驱体中PEG用量为0．1g（0．13wt％）时制取的薄膜具有最佳的光催化活性和较好的透光率,低于或超过这个值,催化降解效果都不理想;镀膜层数为2～5层时,均有较高的透光率,光催化活性依次递增,其中综合效果最佳的为2层镀膜。纳米TiO2镀膜玻璃是一种性能优异的新型自净节能环保材料,在高楼建筑、灯具制造、城市照明系统等领域具有潜在的广泛用途。     

掺杂Er^3＋的TiO2的发射光谱研究

用无水乙醇、冰醋酸、钛酸丁酯凝胶法制备了掺杂Er^3＋的TiO2粉末，测量了其在488m激发下的Stokes发射光谱和980nm激发下的上转换发光光谱。在可见光范围内，观察到了绿光和红光，绿光从500-570nm，对应Er^3＋的^2H11/2,^4S3／2→^4I15/2，红光从650～690m，对应Er^3＋的^4F9／2→^4I15／2的跃迁。由ln Ivis-In Iin曲线可知，绿光和红光均为双光子过程，光强正比于泵浦功率的二次方，即Iout ∝Iin。初步研究了此材料的上转换过程。     

掺杂Er3+的Ti02的发射光谱研究

用无水乙醇、冰醋酸、钛酸丁酯凝胶法制备了掺Er3 的TiO2粉末,测量了其在488 nrn激发下?栽 的Stokes发射光谱和980 nm激发下的上转换发光光谱.在可见光范围内,观察到了绿光和红光,绿光从500～570 nm,对应Er3 的2H11/2,4S/2→4I15/2,红光从650～690 nm,对应Er3 的4F9/2→4I15/2的跃迁.由ln Ivis-ln Iin曲线可知,绿光和红光均为双光子过程,光强正比于泵浦功率的二次方,即Iout∝Iin.初步研究了此材料的上转换过程.     

EPR Study of Fe3+- and Ni2+-Doped Macroporous CaSiO3 Ceramics

Thermally stable macroporous CaSiO₃, Fe³⁺- and Ni²⁺-doped (0.5 to 5 mol%) ceramics have been prepared by solution combustion process by mixing respective metal nitrates (oxidizers), fumed silica. Diformol hydrazine is used as a fuel. The combustion products were identified by their X-ray diffraction and thermal gravimetry/differential thermal analysis. Single phases of β-CaSiO₃ and α-CaSiO₃ were observed at 950 and 1200 °C, respectively. The phase transition temperatures of combustion-derived CaSiO₃ were found to be lower compared to those obtained via solid-state reaction method. It is interesting to note that with an increase in the calcination temperature the samples become more porous with an increase in the pore diameter from 0.2 to 8 μm. The electron paramagnetic resonance (EPR) spectrum of Fe³⁺ ions in CaSiO₃ exhibits a weak signal at g = 4.20 ± 0.1 followed by an intense signal at g = 2.0 ± 0.1. The signal at g = 4.20 is ascribed to isolated Fe³⁺ ions at rhombic site. The signal at g = 2.0 is due to Fe³⁺ coupled together with dipolar interaction. In Ni²⁺-doped CaSiO₃ ceramics the EPR spectrum exhibits a symmetric absorption at g = 2.23 ± 0.1. This deviation from the free electron g-value is ascribed to octahedrally coordinated Ni²⁺ ions with moderately high spin–orbit coupling. The number of spins participating in resonance and the paramagnetic susceptibilities have been evaluated from EPR data as a function of Fe³⁺ as well as Ni²⁺ content. The effect of alkali ions (Li, Na and K) on the EPR spectra of these ceramics has also been studied. Authors' address: R. P. Sreekanth Chakradhar, Glass Technology Laboratory, Central Glass and Ceramic Research Institute, Kolkata 700032, India     

基于Er3+：YAlO3/TiO2的可见光催化降解室内甲醛

为使TiO2能够在可见光下发挥其于紫外激发的高光催化活性降解室内甲醛,采用水热处理法将TiO2与掺杂稀土离子Er3+的上转换发光剂Er3+∶YAlO3结合,制备具有可见光响应的Er3+∶YAlO3/TiO2光催化剂,并对其进行了表征分析。结果表明,TiO2以锐钛矿为主,且Er3+∶YAlO3可有效地将可见光上转换至可激发TiO2的紫外光。在箱式反应器中进行光催化降解气态甲醛,研究了甲醛初始浓度与催化剂用量对甲醛降解效率的影响。结果表明,该光催化反应的假一级反应速率常数( kapp )与甲醛初始浓度成正相关,而随催化剂用量的增加先升高后降低。当甲醛初始浓度为0.058 mg/m3、催化剂用量为0.1224 g/L时,kapp最大为3.65×10-3 min-1。该反应符合Langmuir-Hinshelwood模型,反应速率常数为5×10-8 mg/( L·min)。     

Characterization and Photocatalytic Performance of Rb+-Doped TiO2 Photocatalysts

ABSTRACT

Rb⁺-doped TiO₂ nanoparticles with higher photocatalytic activity were prepared by sol–gel method. The prepared samples were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), energy dispersive analysis of X-rays (EDAX), and surface area (BET) measurements. The photocatalytic activity for the degradation of rhodamine B (RhB) was evaluated. The effects of calcination temperature, Rb⁺-doping amount, and the dosage of catalyst in the reaction liquid were investigated. The results showed that Rb⁺ doping can inhibit phase transformation from anatase to rutile, increase surface area of TiO₂ crystals, and reduce crystallite size. TiO₂ doped with 1% Rb⁺ and calcined at 650°C shows much higher photoactivity than the others when the doping level of Rb⁺ and calcination temperature are 0–5% and 350–850°C, respectively. The kinetics of the degradation of RhB was also analyzed. The kinetics of this reaction fits the pseudo first-order kinetics model well, and the reaction rate constants for pure TiO₂ and Rb1-650 are 0.086 min^?1 and 0.226 min^?1 respectively. Doping with Rb⁺ improves the photocatalytic activity of TiO₂ significantly.     

Fe~(3+)-Doped Anatase TiO_2 Study Prepared by New Sol-Gel Precursors

FeTi_1-O_2(= 0.00,0.05,0.10) nanocomposites are synthesized using a sol-gel method involving an ethanol solvent in the presence of ethylene glycol as the stabilizer,and acetic acid as the chemical reagent.Their structural and optical analyses are studied to reveal their physicochemical properties.Using the x-ray diffractometer(XRD)analysis,the size of the nanoparticles(NPs) is found to be 18–32 nm,where the size of the NPs decreases down to 18 nm when Fe impurity of up to 10% is added,whereas their structure remains unchanged.The results also indicate that the structure of the NPs is tetragonal in the anatase phase.The Fourier transform infrared spectroscopy analysis suggests the presence of a vibration bond(Ti–O) in the sample.The photoluminescence analysis indicates that the diffusion of Fe~(3+) ions into the TiO_2 matrix results in a decreasing electron–hole recombination,and increases the photocatalytic properties,where the best efficiency appears at an impurity of10%.The UV-diffuse reflection spectroscopy analysis indicates that with the elevation of iron impurity,the band gap value decreases from 3.47 eV for the pure sample to 2.95 eV for the 10 mol% Fe-doped TiO_2 NPs.