Photocatalytic activity of TiO2 doped with boron and vanadium

Boron (B)- and vanadium (V)-doped TiO(2) photocatalysts were synthesized using modified sol-gel reaction processes and characterized by X-ray diffraction (XRD), Raman spectroscopy and N(2) physisorption (BET). The photocatalytic activities were evaluated by monitoring the degradation of methylene blue (MB). The results showed that the materials possess high surface area. The addition of B favored the transformation of anatase to rutile, while in the presence of V, anatase was the only phase detected. The MB degradation on V-doped TiO(2) was significantly affected by the preparation method. In fact while the presence of V in the bulk did not influence strongly the photoreactivity under visible irradiation, an increase of surface V doping lead to improved photodegradation of MB. The degradation of MB dye indicated that the photocatalytic activities of TiO(2) increased as the boron doping increased, with high conversion efficiency for 9mol% B doping.     

Photocatalytic activity of La, Y Co-doped TiO2 nanoparticles synthesized by ultrasonic assisted sol-gel method

Bare TiO2 (T), La-doped TiO2 (LT), Y-doped TiO2 (YT), La, Y co-doped TiO2 (LYT) were successfully prepared by facile ultrasonic assisted sol-gel synthesis using Ti(OC4H9)4 as the precursor. The products were characterized by X-ray diffraction (XRD), scanning electron microscope (SEM), UV-visible diffuse reflectance spectra (DRS), and X-ray photoelectron spectroscopy (XPS), respectively. The photocatalytic activities of anatase samples, with the average particle diameters ranging from 14 nm to 21 nm, were evaluated for photodegradation of methyl orange (MO). The XPS results indicated that Y atoms were incorporated into titania lattice, while La atoms existed on the crystal surface. Due to doping, the optical absorption edges of LT, YT, and LYT shifted to the visible light region by 21 nm, 29 nm and 35 nm, respectively. The photocatalytic performances of the doped samples, such as LT, YT and LYT, were much higher than that of bare TiO2 under UV-visible light irradiation. And the photoreactivity efficiency of the LYT was the highest. It indicated that a strong La-Y synergistic interaction appeared to play a decisive role in driving the excellent photocatalytic performance of titania.     

Ce对Na0.5Bi0.5TiO3粉体的掺杂和扩渗改性研究

为改善Na0.5Bi0.5TiO3材料的电性能,采用溶胶-凝胶法制备了Na0.5Bi0.5TiO3粉体.通过液相Ce掺杂和气相Ce扩渗两种方法,对Na0.5Bi0.5TiO3粉体进行了改性,采用扫描电子显微镜(SEM)、X射线衍射仪(XRD)、阻抗分析仪和电阻仪对改性前后Na0.5Bi0.5TiO3粉体的组成、结构和电性能的变化进行了研究.结果表明:Ce元素的添加有助于Na0.5Bi0.5TiO3粉体电阻率的降低,而扩渗改性使电阻率的降低更为显著,经600℃扩渗的Na0.5Bi0.5TiO3粉体的电阻率由3.71×106Ω.m降至2.39×101Ω.m;稀土Ce掺杂使Na0.5Bi0.5TiO3的介电常数减小,而Ce扩渗使Na0.5Bi0.5TiO3的介电常数显著增大;Ce掺杂使粒径更加均匀,而随着气相扩渗温度的提高,晶粒粒径逐渐变大;Ce掺杂没有改变Na0.5Bi0.5TiO3的主晶相结构,但Na0.5Bi0.5TiO3粉体经Ce扩渗后,出现了单质Bi及Bi2Ti2O7、Na2Ti9O19、Na2Ti6O13的特征峰.     

金属Cd~(2+)掺杂TiO_2纳米颗粒的制备及能级结构的影响机理

采用溶胶-凝胶法制备了Cd2+掺杂改性TiO2纳米颗粒,利用XRD、TEM、XPS和UV-Vis光谱对掺杂前后颗粒的结构和性能进行了表征。结果表明,溶胶-凝胶法制备的Cd2+掺杂TiO2纳米颗粒主要为锐钛矿相,粒径尺寸在20nm左右,掺杂前后TiO2的尺寸和形貌没有明显变化;结构表征和光谱测试结果发现,Cd元素在TiO2纳米颗粒中部分取代TiO2晶格中的Ti元素,以Cd2+的形式存在,形成Cd—O键,使TiO2纳米颗粒的吸收带边红移,降低了TiO2的禁带宽度。并且采用基于密度泛函理论的第一性原理对Cd掺杂TiO2进行了能级结构的模拟计算,发现理论结果与实验结果有较好一致性。     

The effect of erbium on the adsorption and photodegradation of orange I in aqueous Er3+-TiO2 suspension

Pure TiO(2) and erbium ion-doped TiO(2) (Er(3+)-TiO(2)) catalysts prepared by the sol-gel method were characterized by means of XRD and diffusive reflectance spectra (DRS). The XRD results showed that erbium ion doping could enhance the thermal stability of TiO(2) and inhibit the increase of the crystallite size, and the DRS results showed that the optical absorption edge slightly shifted to red direction owing to erbium ion doping and the Er(3+)-TiO(2) catalysts had three typical absorption peaks located at 490, 523 and 654 nm owing to the transition of 4f electron from (4)I(15/2) to (4)F(7/2), (2)H(11/2) and (4)F(9/2). With a purpose of azo dyes degradation, orange I was used as a model chemical. And the adsorption isotherm, degradation and mineralization of orange I were investigated in aqueous suspension of pure TiO(2) or Er(3+)-TiO(2) catalysts. The results showed that Er(3+)-TiO(2) catalysts had higher adsorption equilibrium constants and better adsorption capacity than pure TiO(2). The adsorption equilibrium constants (K(a)) of Er(3+)-TiO(2) catalysts were about twice of that of pure TiO(2). The maximum adsorption capacity (Q(max)) of 2.0% Er(3+)-TiO(2) catalyst was 13.08x10(-5)mol/g, which was much higher than that of pure TiO(2) with 9.03x10(-5)mol/g. Among Er(3+)-TiO(2) catalysts, 2.0% Er(3+)-TiO(2) catalyst achieved the highest Q(max) and K(a) values. The kinetics of the orange I degradation using different Er(3+)-TiO(2) catalysts were also studied. The results demonstrated that the degradation and mineralization of orange I under both UV radiation and visible light were more efficient with Er(3+)-TiO(2) catalyst than with pure TiO(2), and an optimal dosage of erbium ion at 1.5% achieved the highest degradation rate. The higher photoactivity under visible light might be attributable to the transitions of 4f electrons of Er(3+) and red shifts of the optical absorption edge of TiO(2) by erbium ion doping.     

Effect of doping (C or N) and co-doping (C+N) on the photoactive properties of magnetron sputtered titania coatings for the application of solar water-splitting

The photocatalytic splitting of water into hydrogen and oxygen using a photoelectrochemical (PEC) cell containing titanium dioxide (TiO2) photoanode is a potentially renewable source of chemical fuels. However, the size of the band gap (-3.2 eV) of the TiO2 photocatalyst leads to its relatively low photoactivity toward visible light in a PEC cell. The development of materials with smaller band gaps of approximately 2.4 eV is therefore necessary to operate PEC cells efficiently. This study investigates the effect of dopant (C or N) and co-dopant (C+N) on the physical, structural and photoactivity of TiO2 nano thick coating. TiO2 nano-thick coatings were deposited using a closed field DC reactive magnetron sputtering technique, from titanium target in argon plasma with trace addition of oxygen. In order to study the influence of doping such as C, N and C+N inclusions in the TiO2 coatings, trace levels of CO2 or N2 or CO2+N2 gas were introduced into the deposition chamber respectively. The properties of the deposited nano-coatings were determined using Spectroscopic Ellipsometry, SEM, AFM, Optical profilometry, XPS, Raman, X-ray diffraction UV-Vis spectroscopy and tri-electrode potentiostat measurements. Coating growth rate, structure, surface morphology and roughness were found to be significantly influenced by the types and amount of doping. Substitutional type of doping in all doped sample were confirmed by XPS. UV-vis measurement confirmed that doping (especially for C doped sample) facilitate photoactivity of sputtered deposited titania coating toward visible light by reducing bandgap. The photocurrent density (indirect indication of water splitting performance) of the C-doped photoanode was approximately 26% higher in comparison with un-doped photoanode. However, coating doped with nitrogen (N or N+C) does not exhibit good performance in the photoelectrochemical cell due to their higher charge recombination properties.     

TiO2-N-S光催化剂的制备、表征及性能研究

以胱氨酸为掺杂剂,利用溶胶-凝胶法直接制备了N、S共掺杂改性的光催化剂TiO2-N-S,借助XRD、XPS和SPS等手段对其进行了表征,并以苯酚为模型污染物考察了其在模拟太阳光下的催化活性.XRD分析表明该光催化剂为锐钛矿晶型,N、S共掺杂能有效抑制TiO2晶粒的生长,提高了晶相间转变温度.XPS显示S是以S6+形式存...     

N、Fe双掺杂的纳米TiO2制备及其性能研究

采用溶胶-凝胶法制备了N、Fe双掺杂的纳米TiO2光催化材料.借助XRD、XPS对制备的光催化材料进行表征,并通过晶粒尺寸、晶粒比表面积和晶格畸变率等的分析,研究了N、Fe双掺杂对TiO2性能的影响.研究结果表明,N、Fe双掺杂抑制了TiO2由锐钛矿向金红石的转变,明显延缓了TiO2相的转移;N、Fe双掺杂可明显减小晶...     

Microstructure Characterization of Sol-gel Prepared MoO3-TiO2 Thin Films for Oxygen Gas Sensors

Binary metal oxide MoO3-TiO2 films have been prepared using the sol-gel technique. The thin films were annealed at several temperatures including 400℃,450℃,500℃,550℃ and 600℃ for lhour. The morphology, crystalline structure and chemical composition of the films have been analysed using SEM,XRD,RBS and XPS techniques. The SEM analysis showed that the films annealed at 450℃ are mainly smooth and uniform with 20-100nm-sized grains and with few particles as large as a micrometre or more. The XRD analysis revealed that the films annealed at 400℃ were a mixture of orthorhombic and hexagonal MoO3phases. The films annealed at 450℃ increased in hexagonal phase. The preferential orientation growth along(100) plane of the hexagonal phase and (010) plane of the orthorhombic phase has been found in both samples. RBS and XPS analysis showed that the films were stoichiometric. When the annealing temperature is increased to more than 500℃, the concentration ratio of MoO3 to TiO2 decreased due to the evaporation of MoO3. For the study of the electrical and gas sensing properties, films were deposited on sapphire substrates with interdigital electrodes on the front-side and a Pt heater on the backside. The O2 gas sensing properties of MoO3-TiO2 thin films are discussed.     

V-N共掺杂TiO_2/玻璃珠光催化复合材料的制备及光催化性能

用溶胶-凝胶法制备V-N-TiO_2/玻璃珠光催化复合材料,研究V-N-TiO_2(V-N-TiO_2)的浓度、V-N-TiO_2/玻璃珠的浸渍次数、玻璃珠尺寸、煅烧温度和煅烧时间对V-N-TiO_2/玻璃珠光催化复合材料光催化性能的影响。采用XRD、EDS、TEM、XPS等测试手段对复合材料的结构和性能进行表征;在100 W汞灯下,以苯酚溶液为目标降解物,对V-N-TiO_2/玻璃珠光催化复合材料光催化性能进行测定。研究表明:当V-N-TiO_2/玻璃珠的浸渍次数为4次、玻璃珠尺寸为2~3mm、煅烧温度为400℃和煅烧时间为4.5h时,得到的V-N-TiO_2/玻璃珠光催化复合材料对苯酚的光催化性能最佳,且单位催化剂对苯酚的降解量略高于V-N-TiO_2。V-N-TiO_2/玻璃珠光催化复合材料既易于回收,又具有良好的光催化性能。     

氮掺杂TiO_2的制备及其光催化性能研究

应用溶胶-凝胶法,以尿素和钛酸丁酯为原料制备前躯体,前躯体在500℃、焙烧3 h条件下制备不同浓度掺杂氮的TiO2纳米粉体。采用X射线衍射(XRD)、扫描电镜(SEM)、能谱分析(EDS)、紫外可见光谱(UV-Vis)等分析手段对样品的物相、形貌、成分和吸光性能进行表征,并且以亚甲基蓝溶液为模拟污染物在阳光下进行光催化实验。结果表明:样品主要为锐钛矿相二氧化钛及少量的金红石型二氧化钛,颗粒粒径小于300 nm,有一定程度的团聚,样品中含有质量分数分别为0、2.99%、6.23%、11.38%的氮元素,氮掺杂样品的光谱吸收边缘红移至400~470 nm。光催化实验表明:氮掺杂可以大大改善TiO2在可见光波段的光催化性能。     

锐钛矿型银掺杂二氧化钛紫外光及模拟太阳光光催化性能

以钛酸丁酯、硝酸银为原料,采用溶胶-凝胶法制备不同浓度Ag掺杂TiO2光催化剂。分别采用X射线衍射(XRD)、扫描电子显微镜(SEM)、光电子能谱(XPS)、紫外可见漫反射(DRS)及荧光光谱(PL)等测试方法对样品晶体结构、表面形貌、化学成分和光学性质进行表征。以罗丹明B溶液(RhB)为目标降解物,分别采用汞灯与氙灯为光源,研究xAg-TiO2(x=1%,2%,4%,6%,原子分数)光催化剂在紫外光和模拟太阳光照射下的光催化活性。结果表明:Ag的加入降低了光生电子空穴的复合率,增加了对模拟太阳光的吸收,紫外光以及模拟太阳光的光催化活性均得到提升。1%Ag-TiO2表现出最好的光催化活性,在紫外光及模拟太阳光下对RhB的降解率分别为91%与89%,是纯TiO2的1.18倍和1.24倍,反应速率常数k分别为0.01257 min^-1和0.01150 min^-1,是纯TiO2的1.49倍和1.74倍。     

Photocatalytic degradation of monocrotophos pesticide--an endocrine disruptor by magnesium doped titania

Mg-doped TiO(2) with different Mg concentrations were prepared using sol-gel method and characterized by XRD, UV-visible, XPS, SEM and FT-IR. The XRD results revealed that Mg(2+) goes into the TiO(2) lattice. SEM images of the doped and pure TiO(2) indicated that there is a smaller particle size for the doped catalyst compared to that of the pure TiO(2). UV-visible absorption spectra indicated that upon doping with Mg(2+) ion, the catalyst exhibits absorption in visible region. FT-IR and XPS spectra demonstrated that the presence of Mg(2+) ion in the TiO(2) lattice as substitutional dopant. Photocatalytic activity of doped TiO(2) has been evaluated by degradation of the monocrotophos (MCP) pesticide. The effect of solution pH, catalyst dosage and initial concentration of MCP on the photocatalytic activity of Mg-doped TiO(2) with different loadings was studied. It was observed that the rate of degradation of MCP over Mg-doped TiO(2) is better than Pure TiO(2) and Degussa P-25.     

掺杂纳米TiO_2粉体的制备及其光电性能研究

利用Zn2+离子掺杂纳米二氧化钛,以提高其光电转化性能,通过溶胶-凝胶法制备了Zn2+离子掺杂的纳米二氧化钛粉体,采用X射线衍射、扫描电镜、紫外可见光谱和光诱导产生光电流法对掺杂二氧化钛的物相、形貌、光吸收性能和光电性能进行了表征。研究发现,Zn2+掺杂有利于锐钛矿的结晶,掺杂二氧化钛较纯二氧化钛的紫外吸收边红移了约10nm,当Zn2+掺杂量为Ti物质的量的1%时光电转化性能最佳。     

共掺杂Cu-Ce/TiO_2光催化性能研究

采用溶胶-凝胶法,以钛酸丁酯为前驱体制备了不同Cu-Ce掺杂量的纳米TiO2光催化材料。通过模拟环境室内甲醛气体的降解实验,探讨了不同样品在日光灯和纯可见光下的光催化效果,并采用X射线衍射仪和紫外-可见分光光谱仪对其晶相结构与光学特性进行表征分析。结果表明,Cu-Ce掺杂能明显提高二氧化钛在可见光下的光催化活性,当Cu-Ce掺杂浓度为2.5%时,对甲醛气体的光催化降解效果最佳。     

复合半导体光催化材料ZnFe2O4-TiO2/SiO2结构与光响应性能研究

采用溶胶．凝胶法制备了负载型复合半导体光催化材料ZnFe2O4-TiO2／SiO2，并通过DTA-TG、XRD、XPS、Raman、TPR及UV-Vis DRS等实验技术对复合材料的晶体结构、表面组成及光响应性能进行了表征和评价．结果表明：ZnFe2O4晶相以高分散状态存在于光催化材料的表面；ZnFe2O4与TiO2复合可使部分Fe^3＋进入体相TiO2的晶格中，促进其由锐钛矿向金红石的相转变，同时表面剩余的少量Zn计聚集形成ZnO物相；TiO2的相变由体相开始，随着ZnFe2O4含量的增加逐渐向表面扩展；SiO2的加入使活性组分更加分散，TiO2平均粒径〈10nm；ZnFe2O4的加入明显拓宽了TiO2的吸光域，并增强了对可见光的吸收．     

Novel Bi(2)WO(6)-TiO(2) heterostructures for Rhodamine B degradation under sunlike irradiation

Highly efficient Bi(2)WO(6)-TiO(2) heterostructure is synthesized by means of a hydrothermal method having highly photoactivity for the degradation of Rhodamine B under sunlike irradiation. From the structural characterization it has been demonstrated that TiO(2) is incorporated on the Aurivillius structure. Interesting synergetic effect between TiO(2) and Bi(2)WO(6) leads to an improved charge carrier separation mechanism, causing the excellent photocatalytic performance under sunlike irradiation. The photocatalytic performance of Bi(2)WO(6) and Bi(2)WO(6)-TiO(2) was compared under different irradiation conditions and using increasing Rhodamine B concentration up to 25 ppm. After the photocatalytic analysis of both systems, the mineralization efficiency of the heterostructure appears significantly higher with respect to Bi(2)WO(6).     

Ru掺杂TiO2和TiO2/SiO2光催化剂的制备及可见光分解水制氢性能研究

采用溶胶-凝胶法制备了系列Ru/TiO2和Ru/TiO2/SiO2可见光活性光催化剂。通过TEM、XPS、XRD、UV-Vis漫反射和电化学对样品进行了表征。发现Ru和Si的存在可以抑制TiO2的相转变和晶粒生长;Ru掺杂使TiO2和TiO2/SiO2对可见光的吸收增强,也提高了光生电子和空穴的分离,因而,提高了催化剂可见光分解水制氢活性。当Ru在TiO2和TiO2/SiO2中的掺杂量分别为0.014%和0.021%(质量分数)时,光催化剂的可见光活性最高,且Ru/TiO2/SiO2活性为Ru/TiO2的5倍。     

Effect of filler types and calcination temperature on the microstructure and the nitric oxide photocatalytic activity of composite titanium dioxide films

The composite titanium dioxide (TiO(2)) films coating on the woven glass fabric were prepared by a modified sol-gel process, using pre-calcinated TiO(2) nanoparticle or silica gel as filler. The characterized physicochemical properties of the prepared catalyst films showed that the specific surface area, the microstructure and the crystal structure of the catalysts were greatly affected by the fillers and the calcination temperature. The physicochemical properties of composite films and the photocatalytic activity of nitric oxide (NO) show that the pre-calcinated TiO(2) nanoparticle is more favorable than silica gel as filler. The pre-calcinated TiO(2) nanoparticle filler can increase the photocatalytic activities of the catalysts by increasing the specific surface area, introducing a bimodal mesoporous structure, and creating a polymorphous crystal structure. And the TiO(2)-TiO(2) film calcinated at 400 degrees C exhibits the highest photocatalytic activity for NO oxidation and is more active than Degussa P25.     

溶胶-凝胶法制备N-卤素共掺杂TiO_2可见光催化材料

为满足低温制备N掺杂TiO2可见光催化材料的需要,采用溶胶-凝胶法,以十六烷基三甲基氯(溴、碘)化铵为掺杂剂,在回流条件下与TiO2纳米晶溶胶直接反应,制备TiO2光催化材料T5100-C、T5100-B、T5100-I。通过XPS分析,只有样品T5100B成功地在TiO2晶格中掺入了N、Br。UV-Vis漫反射吸收光谱和亚甲基兰(MB)的可见光降解实验表明,样品T5100-B具有良好的可见光响应和光催化活性;而样品T5100-C和T5100-I没有明显的可见光响应和可见光催化活性。N的掺杂使得样品T5100-B具有明显的可见光吸收,而Br的掺杂可以阻止光生电子/空穴对的复合,二者共同提高可见光催化活性。