N掺杂可见光化催化剂的研究

The N-doped, yellow colored titanium oxide photocatalysts were prepared with Ti(SO4)2 and NH4HCO3 as precursors by precipitation method. The photocatalytic ability under the irradiation of UV or visible light for the catalysts prepared was studied by degradation of styphnic acid. The materials were characterized by EDS, XRD, FTIR, UV-Vis DRS, and XPS. The results indicate that the photocatalytic ability of catalysts is improved, especially the ability of visible light response. The results of UV-Vis DRS show that the response wavelength range of N-dopped nitrogen is red shifted, the absorption region is expanded to 476 nm.     

Preparation and characterization of In and Cu co-doped ZnS photocatalysts for hydrogen production under visible light irradiation

In this work, a new photocatalyts In(0.1),Cu(x)-Zn S(x = 0.01, 0.03, 0.05) is successfully synthesized using simple hydrothermal method. The physical and chemical properties of the In and Cu co-doped Zn S photocatalyst were characterized by X-ray diffraction(XRD), field emission scanning electron microscopy(FESEM), diffuse reflectance UV-visible spectroscopy(DR UV-visible) and photoluminescence spectroscopy(PL). The photocatalytic activity of the as-prepared In and Cu co-doped Zn S for hydrogen production from water with Na_2SO_3 and Na_2S as sacrificial agent under visible light irradiation(λ≥ 425 nm) was investigated. The presence of co-dopants facilitated the separation of electron-hole as well as increases the visible light absorption. The absorption edge of the co-doped Zn S photocatalyst shifted to longer wavelength as the amount of Cu increases. This indicates that the absorption properties depended on the amount of Cu doped. The photocatalytic activity of single doped In(0.1)-Zn S was significantly enhanced by co-doping with Cu under visible light irradiation. The highest photocatalytic activity was observed on In(0.1),Cu(0.03)-Zn S with the hydrogen production rate of 131.32 μmol/h under visible light irradiation.This is almost 8 times higher than single doped In(0.1)-Zn S.     

Photocatalytic Activity for Water Decomposition to Hydrogen over Nitrogen‐doped TiO2 Nanoparticle

Nitrogen-doped TiO2 nanoparticle photocatalysts were obtained by an annealing method with gaseous ammonia and nitrogen. The influence of dopant N on the crystal structure was characterized by XRD, XPS, BET, TEM and UV-Vis spectra. The results of XRD indicate that, the crystal phase transforms from anatase to rutile structure gradually with increase of annealing temperature from 300 to 700 ℃. XPS studies indicate that the nitrogen atom enters the TiO2 lattice and occupies the position of oxygen atom. Agglomeration of particles is found in TEM images after annealing. BET results show that the specific surface areas of N-doped samples from 44.61 to 38.27 m2/g are smaller than that of Degussa TiO2. UV-Vis spectra indicate that the absorption threshold shifts gradually with increase of annealing temperature, which shows absorption in the visible region. The influence of annealing condition on the photocatalytic property has been researched over water decomposition to hydrogen, indicating that nitrogen raises the photocatalytic activity for hydrogen evolution, and the modified TiO2 annealed for 2 h at 400 ℃ under gas of NH3/N2 (V/V＝1/2) mixture shows better efficiency of hydrogen evolution. Furthermore, the N-doped TiO2 nanoparticle catalysts have obvious visible light activity, evidenced by hydrogen evolution under visible light (λ＞400 nm) irradiation. However, the catalytic activity under visible light irradiation is absent for Degussa as reference and the N-doped TiO2 annealed at 700 ℃.     

Photoreduction of CO_2 to methanol over Bi_2S_3/CdS photocatalyst under visible light irradiation

The Bi2S3,CdS and Bi2S3/CdS photocatalysts were prepared by direct reactions between their corresponding salt and thiourea in a hy- drothermal autoclave.The photocatalytic activities of these photocatalysts for reducing CO2 to CH3OH under visible light irradiation have been investigated.The results show that the photocatalytic activity and visible light response of Bi2S3 are higher than those of CdS.The Bi2S3 modification can enhance the photocatalytic activity and visible light response of CdS.The photocatalytic activity of Bi2S3/CdS hetero-junction photocatalyst was the highest and the highest yields of methanol was 613μmol/g when the weight proportion of Bi2S3 to CdS was 15%,which was about three times as large as that of CdS or two times of that of Bi2S3.     

Magnetically recoverable Cu2O/Fe3O4 composite photocatalysts：Fabrication and photocatalytic activity

A magnetically separable Cu2O/Fe3O4 magnetic composite photocatalyst was synthesized in large quantities by a fast and simple route. The as-prepared photocatalysts were characterized by scanning electron microscopy （SEM）, transmission electron microscopy （TEM）, X-ray photoelectron spectroscopy （XPS） and X-ray diffraction （XRD）. Furthermore, the Cu2O/Fe3O4 composite photocatalysts were tested using methyl orange （MO） degradation reaction under visible light irradiation （100 mW/cm2） and demonstrated to have a high photocatalytic efficiency toward the decomposition of MO under visible light irradiation with good recyclability.     

Characterization and photocatalytic properties of silver and silver chloride doped TiO2 hollow nanoparticles

Using polystyrene（PSt） particles as template,PSt/TiO₂ composite particles with AgCl incorporation were prepared through hydrolysis of tetrabutyl titanate in the presence of AgNO₃ and NaCl.AgCl doped TiO₂ hollow particles were successfully prepared with the PSt/TiO₂ composite microspheres pretreated at 180℃followed by calcination.The morphology of PSt/TiO₂ particles and the crystal structures of the AgCl doped TiO₂ hollow particles were characterized.The photocatalytic activity of the doped TiO₂ hollow particles in degradation of Rhodamine B was tested under UV and visible lights and compared to that with Ag doped TiO₂ particles.The results showed that TiO₂ hollow particles,either doped with Ag or AgCl,demonstrated higher photocatalytic activity than the pure TiO₂ particles.This enhancement in photocatalytic activity was more significant with AgCl doped TiO₂ than that with Ag doped,and more distinct when the degradation was done under visible light than that under LTV light.     

Synthesis and characterization of sulfur-titanium dioxide nanocomposites for photocatalytic oxidation of cyanide using visible light irradiation

A sol-gel method was used to prepare TiO2and sulfur-TiO2(S-TiO2)nanocomposites, which were characterized by N2 adsorption-desorption, X-ray diffraction, X-ray photoelectron spectroscopy, photoluminescene, ultraviolet visible and transmission electron microscopy measurements. The photocatalytic performance of TiO2 and S-TiO2nanocomposites, with respect to the photocatalytic oxidation of cyanide under visible light irradiation, was determined. The results reveal that S is well dispersed on the surface of TiO2 nanoparticles. Additionally, the surface area of the S-TiO2nano-composites was observed to be smaller than that of the TiO2nanoparticles because of blocked pores caused by doping with S. The S-TiO2nanocomposite (0.3 wt% S) exhibited the lowest band gap and the highest photocatalytic activity in the oxidation of cyanide. The photocatalytic performance of S-TiO2(0.3 wt% S) nanocomposites was stable, even after the fifth reuse of the nanoparticles for the oxidation of cyanide.     

Synthesis and photocatalytic properties of core–shell TiO~2@ZnIn_2S_4 photocatalyst

A novel core–shell TiO2@ZnIn2S4composite has been synthesized successfully by a simple and flexible hydrothermal route using TiO2as precursors.The as-synthesized samples were characterized by X-ray diffraction,UV–vis diffuse reflectance spectra and transmission electron microscopy.The photocatalytic properties of samples were tested by degradation of aqueous methylene blue（MB）under visible light irradiation.It was found that the as-synthesized TiO2@ZnIn2S4photocatalyst was more effcient than TiO2and ZnIn2S4in the photocatalytic degradation of MB.Moreover,TEM images confrmed the TiO2@ZnIn2S4nanoparticles possessed a well-proportioned core–shell morphology.     

Preparation and Photocatalytic Activity of Ce,H3PW12O40 co-doped TiO2 Hollow Fibers

A series of Ce, H3PW12O40 co-doped TiO2 hollow fibers photocatalysts have been prepared by sol-gel method using ammonium ceric nitrate, H3PW12O40 and tetrabutyltitanate as precursors and cotton fibers as template, followed by calcination at 500 ℃ in N2 atmosphere for 2 h. Scanning electron microscopy, X-ray diffraction, nitrogen adsorption-desorption mea- surements, and UV-Vis spectroscopy are employed to characterize the morphology, crystal structure, surface structure, and optical absorption properties of the samples. The photo- catalytic performance of the samples has been studied by photodegradation phenol in water under UV and visible light irradiation. The results show that the TiO2 fiber materials have hollow structures, and the co-doped TiO2 hollow fibers exhibit higher photocatalytic activities for the degradation of phenol than un-doped, single-doped TiO2 hollow fibers under UV and visible light. In addition, the recyclability of co-doped TiO2 fibers is also confirmed that the TiO2 fiber retains ca. 90% of its activity after being used four times. It is shown that the co-doped TiO2 fibers can be activated by visible light and may be potentially applied to the treatment of water contaminated by organic pollutants. The synergistic effect of Ce and H3PW12O40 co-doping plays an important role in improving the photocatalytic activity.     

Photocatalytic reduction of carbon dioxide to methanol by Cu2O/SiC nanocrystallite under visible light irradiation

The Cu2O/SiC photocatalyst was obtained from SiC nanoparticles (NPs) modified by Cu2O. Their photocatalytic activities for reducing CO2 to CH3OH under visible light irradiation have been investigated. The results indicated that besides a small quantity of 6H-SiC, SiC NPs mainly consisted of 3C-SiC. The band gaps of SiC and Cu2O were estimated to be about 1.95 and 2.23 eV from UV-Vis spectra, respectively. The Cu2O modification can enhance the photocatalytic performance of SiC NPs, and the largest yields of methanol on SiC, Cu2O and Cu2O/SiC photocatalysts under visible light irradiation were 153, 104 and 191μmol/g, respectively.     

Y2O3/Ag3VO4复合可见光催化剂的制备及其光催化性能

以Na3VO4.12H2O,AgNO3和Y(NO3)3.6H2O为原料,采用浸渍法制备了Y2O3/Ag3VO4复合可见光催化剂,并用XRD,SEM,XPS,UV-Vis等测试手段表征了试样的结构和性能。结果显示,Y2 O3/Ag3VO4复合可见光催化剂为单斜结构,Y以Y2 O3的形式分散在Ag3VO4晶体的表面。UV-Vis测试结果表明,Y2O3/Ag3VO4较纯Ag3VO4吸收带边发生了红移,在可见光区的吸收增强;以金属卤灯(波长大于400 nm)为光源,研究了Y2O3/Ag3VO4催化剂对甲基橙(MO)的可见光催化降解性能。结果发现,Y2O3/Ag3VO4复合可见光催化剂的光催化活性较纯Ag3VO4均有大幅提高,其中Y掺杂量为4%时活性最高。     

乙酸修饰Ag/TiO2复合光催化剂的制备及协同催化性能

利用光化学还原法制备了Ag/TiO₂,然后通过乙酸浸渍制备了HAc-Ag/TiO₂复合光催化剂.利用X射线衍射（XRD）、透射电子显微镜（TEM）、傅里叶变换红外光谱（FTIR）、X射线光电子能谱（XPS）和紫外-可见漫反射光谱（UV-Vis DRS）等手段表征了催化剂的性质.以降解水溶液中的甲基橙（MO）为探针反应,考察了催化剂在可见光下的光催化性能.结果表明,乙酸对TiO₂的修饰在TiO₂禁带中产生了"带尾",使TiO₂的禁带宽度发生了显著的缩减;Ag纳米粒子和乙酸共同修饰的HAc-Ag/TiO₂样品具有更窄的禁带宽度和更正的价带顶位置;Ag和乙酸的协同作用使HAc-Ag/TiO₂具有良好的可见光催化活性：可见光照射2 h后,甲基橙在HAc-Ag/TiO₂上的降解率接近100%.     

Ag修饰的Fe_3O_4/TiO_2复合磁性纳米纤维的制备及光催化性能

通过静电纺丝法制备了含有Fe3O4纳米粒子的TiO2纳米纤维,采用水热法对该纤维表面进行纳米Ag修饰,制备出具有较强磁性和较好光催化性能的复合纤维.采用X射线衍射(XRD)、扫描电子显微镜(SEM)、透射电子显微镜(TEM)和紫外-可见光谱(UV-Vis)等对样品的结构和形貌进行表征,并以罗丹明B(Rh B)水溶液降解为模型反应,考察样品在紫外光照射下的光催化性能.结果表明,所制备的TiO2为锐钛矿结构,Fe3O4纳米粒子均匀分布在TiO2纤维中,Ag纳米颗粒比较均匀地分散在磁性TiO2纤维表面.经过纳米Ag修饰后,材料的光吸收能力大为增强,吸收带红移并扩展到可见光区.在紫外光照射40 min后,合成样品对Rh B的降解率达到99.5%.此外,Fe3O4纳米粒子的存在使该材料具有较强的磁性,可通过外加磁场将其分离回收.     

Ag/BiOX (X=Cl,Br, I)复合光催化剂的制备、表征及其光催化性能

采用光化学沉积法制备了一系列不同Ag含量的新型Ag/BiOX(X=Cl,Br,I)复合光催化剂,应用X射线粉末衍射(XRD)、扫描电镜(SEM)、X射线光电子能谱(XPS)、光致发光(PL)谱、紫外-可见(UV-Vis)光谱和N2物理吸附等手段对催化剂进行表征,并以420nm<λ<660nm的可见光为光源,评价了该催化剂光催化降解酸性橙II的活性,考察了不同含量的Ag沉积对BiOX样品光催化性能的影响.N2物理吸附测试结果表明,沉积银在一定程度降低了催化剂的比表面积.UV-Vis测试结果表明,Ag能产生表面等离子共振吸收,有效增强BiOCl和BiOBr对可见光的吸收能力.PL测试结果则表明,Ag能显著抑制光生电子(e-)和空穴(h+)的复合.Ag的存在大幅度提高了BiOX对染料的光催化降解活性.当负载Ag的质量分数(w)为1%-2%时,可使BiOCl、BiOBr和BiOI光催化活性分别提高了10、13和2倍.Ag/BiOX复合光催化剂具有更高催化活性的原因是复合光催化剂对可见光有很强的吸收能力,同时产生了银等离子体光催化作用和银抑制了Ag/BiOX(X=Cl,Br,I)的光生电子-空穴的复合.     

C-N-S-TiO2光催化剂的制备、表征及其性能

以钛酸四丁酯为钛源、功能生物小分子胱氨酸为掺杂剂,采用溶胶-凝胶法同步合成了C-N-S-TiO2光催化剂,利用XRD、XPS、FT-IR和DRS等测试技术对样品的结构及物化性能进行了表征。XRD和DRS分析表明,共掺杂抑制了TiO2晶粒的生长,提高了晶相转变温度,且C-N-S-TiO2样品的吸收带边明显"红移",光吸收范围一直延长至800 nm左右。XPS分析结果显示,C-N-S-TiO2样品表面产生了杂质能级,C、S元素分别取代部分晶格Ti4+以CO23-和S6+形式存在;而N峰呈宽化状态,以O—Ti—N和Ti—O—N键存在,且样品表面羟基含量明显增加。以罗丹明B染料为模型污染物,考察了该催化剂的可见光催化活性。结果表明,与P25 TiO2比较,C-N-S-TiO2光催化剂活性得到改进,C-N-S-TiO2光催化剂在470～800 nm波长下辐射120 min后对罗丹明B的降解率可高达83%。     

微波辅助制备CdS插层K2La2Ti3O10复合物及其光催化制氢的性能

采用微波辅助通过酸交换、胺柱撑、离子交换等步骤制备了CdS插层的K2La2Ti3O10(记做CdS-K2La2Ti3O10)复合光催化剂.利用X射线粉末衍射(XRD),场发射扫描电子显微镜(SEM),紫外-可见漫反射吸收光谱(UV-Vis)和光致发光光谱(PL)等对产物进行表征,考察了CdS-K2La2Ti3O10在紫外光及可见光下催化制氢活性.结果表明,微波辅助法与传统法制备的插层复合催化剂晶型结构相似,同时大大减少了离子交换反应时间,减少了对层间结构的破坏,拓展了催化剂的可见光吸收范围.微波辅助制备的催化剂在紫外光和可见光照射3 h后的产氢量分别为221.53 mmol/(g cat.)和3.23 mmol/(g cat.),并对光催化机理进行了分析.     

具有不同Bi/Ti摩尔比的BiOI/TiO2 (A)光催化剂的结构与性能

在室温条件下通过沉积法制备了BiOI敏化纳米锐钛矿TiO₂ (A)光催化剂. 用X射线衍射(XRD),X射线光电子能谱(XPS), 光致发光(PL)光谱和紫外-可见漫反射(UV-Vis DRS)等手段对其进行了表征. 通过罗丹明B(RhB)催化降解实验评价了其光催化活性. 随BiOI含量增加, BiOI/TiO₂ (A)在370-630 nm的吸收强度增强, 吸收带边红移增加, 紫外和可见光催化活性先增加, 当BiOI含量约为1.7% (质量分数)时, 各自达到最大值, 然后随BiOI含量的进一步增加而减小. 1.7% BiOI/TiO₂ (A)的可见光活性明显高于P25, 它的紫外光活性也略高于P25. 在BiOI含量相近时, BiOI/TiO₂ (A)比BiOI/P25具有更低的光催化活性. 和TiO₂ (A)相比, 1.7% BiOI/TiO₂ (A)明显具有更高的紫外和可见光催化活性, 这归功于它在370-630 nm的强吸收、吸收带边红移明显以及光生电子和空穴的有效转移, 减少了电子-空穴对的复合.     

Bi3.25La0.75Ti3O12纳米线的可见光催化性能

研究了用一步水热法制备的掺镧钛酸铋(Bi_3.25La_0.75Ti₃O₁₂, BLT)纳米线的光学和可见光催化性能, 并对其晶体结构和微观结构用X射线衍射(XRD)、透射电子显微镜(TEM)和高分辨透射电子显微镜(HRTEM)等手段进行了表征. 结果表明, 制备的纳米线为纯相的Bi_3.25La_0.75Ti₃O₁₂, 平均直径约为25 nm. 室温光致发光谱(PL)显示BLT纳米线在433和565 nm附近有较强的发射峰, 分别对应激子发射和表面缺陷发光. 紫外-可见漫反射光谱(UV-Vis DRS)表明BLT样品的带隙能约为2.07 eV. 利用可见光(λ>420 nm)照射下的甲基橙降解实验评价了BLT样品的光催化性能. 结果表明, BLT的光催化活性比商用TiO₂催化剂P25、掺氮TiO₂和纯相钛酸铋(Bi₄Ti₃O₁₂, BIT)高得多. BLT光催化剂具有更高催化活性的原因是La³⁺离子掺杂拓展了BIT对可见光的吸收范围, 同时抑制了BIT的光生电子-空穴的复合.     

Ag负载CdMoO4光催化剂的制备及其催化性能

采用硼氢化钠还原法制备了Ag负载CdMoO₄光催化剂。运用X射线粉末衍射（XRD）、扫描电镜（SEM）和透射电镜（TEM）等测试手段对催化剂的组成和结构进行了表征;采用紫外-可见漫反射光谱（UV-Vis DRS）和X射线光电子能谱（XPS）等技术对催化剂的光响应和表面状态进行了分析,考察了不同Ag负载量对CdMoO₄紫外光降解罗丹明B和可见光选择性氧化苯甲醇性能的影响。结果表明,与CdMoO₄相比,Ag/CdMoO₄具有更高的光催化活性。利用活性物种捕获实验探讨其光催化降解过程的反应机理,实验结果显示O₂^-·和·OH是光催化降解过程的主要活性物种。     

Ag负载CdMoO4光催化剂的制备及其催化性能

采用硼氢化钠还原法制备了Ag负载Cd Mo O4光催化剂。运用X射线粉末衍射(XRD)、扫描电镜(SEM)和透射电镜(TEM)等测试手段对催化剂的组成和结构进行了表征;采用紫外-可见漫反射光谱(UV-Vis DRS)和X射线光电子能谱(XPS)等技术对催化剂的光响应和表面状态进行了分析,考察了不同Ag负载量对Cd Mo O4紫外光降解罗丹明B和可见光选择性氧化苯甲醇性能的影响。结果表明,与Cd Mo O4相比,Ag/Cd Mo O4具有更高的光催化活性。利用活性物种捕获实验探讨其光催化降解过程的反应机理,实验结果显示O2-·和·OH是光催化降解过程的主要活性物种。