表面修饰碳纳米管/二氧化钛复合光催化剂制备及催化活性研究

采用溶胶-凝胶法在聚乙烯吡咯烷酮(PVP)修饰的碳纳米管表面均匀沉积纳米级二氧化钛粒子制得复合光催化剂。采用透射电子显微镜(TEM)、X射线衍射仪(XRD)、紫外-可见吸收光谱仪(UV-Vis)和X射线光电子能谱仪(XPS)等手段对复合光催化剂进行表征。结果表明,二氧化钛粒子是呈球形、团聚,随机沉积在未修饰碳纳米管任意表面,甚至部分碳纳米管表面是完全裸露的。经PVP修饰后的碳纳米管,二氧化钛纳米粒子均匀沉积在碳纳米管表面,二氧化钛为纯锐钛矿晶体结构,没有金红石和板钛矿相。表面修饰碳纳米管/二氧化钛复合光催化剂在紫外光照射下降解亚甲基蓝,相比纯的二氧化钛和碳纳米管/二氧化钛复合光催化剂,具有非常高的催化活性。     

介孔二氧化钛光催化降解乙醛及其影响因素

"应用溶剂蒸发自组装的方法合成了具有蠕虫状孔道的介孔二氧化钛粉末和薄膜．考察了不同焙烧温度对材料介孔结构和光催化性能的影响．乙醛光催化降解实验用来表征不同焙烧温度下介孔材料的光催化性能．结果表明实验中合成的介孔二氧化钛材料的光催化活性明显高于颗粒二氧化钛(Degussa P25)．其中400 oC焙烧的样品具有平均孔径为6.0 nm的窄的孔径分布和117 m2/g的大的比表面积．通过对光催化活性结果的分析,发现介孔二氧化钛的活性主要受其比表面积和结晶性的共同影响．对介孔二氧化钛薄膜材料进行了同样的光催化表     

掺磷TiO_2优化TiO_2/MBA/Ag三明治结构的SERS性能

本文以磷酸为磷源,通过溶胶水热法制备磷掺杂TiO_2,利用Lee和Meisel的方法制备银溶胶,以4-巯基苯甲酸(MBA)为探针分子,通过构建TiO_2/MBA/Ag三明治结构,研究磷掺杂二氧化钛对该基底表面增强拉曼(SERS)性能的提升。通过TEM、XRD、XPS、DRS和拉曼光谱图表征二氧化钛的形貌结构、化学组成、光学和拉曼性能,结果表明,制备出的磷掺杂二氧化钛为锐钛矿型纳米颗粒,粒径范围6~12nm,XPS显示磷以P~(5+)替代了Ti~(4+),形成O-P-O键掺入TiO_2的晶格中,当磷的掺杂量在1.77%时,TiO_2/MBA/Ag三明治体系具有最佳的SERS信号,这是因为适量的磷掺杂降低了TiO_2的能带间隙,丰富TiO_2的表面态,这能促进TiO_2向MBA分子的电荷转移。     

Enhanced photocatalytic activity of silver metallized TiO2 particles in the degradation of an azo dye methyl orange: Characterization and activity at different pH values

The photocatalytic activity of silver deposited Degussa P25 titanium dioxide (Ag-DP25) in the photodegradation of methyl orange (MO) was investigated. The photocatalysts were characterized using PXRD, SEM, EDX, FTIR and UV-vis spectrophotometer. The obtained results show that the silver (Ag⁰) deposited TiO₂ exhibited visible light plasmon absorption band. The degradation experiment reveals that the catalytic property of Ag-DP25 in the degradation of MO is more efficient than that of commercially available Degussa P25 TiO₂ (DP25) samples. The improvement of Ag-DP25 catalyst efficiency strongly depends on the content of silver (Ag) deposits. The present study shows that the degradation process is dominated by Ag-TiO₂ photocatalytic system, complying with pseudo-first order rate law. The higher rate of photodegradation observed on Ag-DP25 at pH 6.6 can be correlated to the ratios of the concentrations of the ionized to the neutral dye molecules and also to the higher concentration of hydroxylated surface, which are able to effectively scavenge photogenerated valence band holes. Accumulation of the holes in the semiconductor particles increases the probability of formation of excited oxygen atom which is a reactive species readily oxidizing the organic dye molecule. The reduction of pH during the course of the reaction is attributed to the complete mineralization of the dye.     

Selective oxidation of CO in the presence of air over gold-based catalysts Au/TiO2/C (sonochemistry) and Au/TiO2/C (microwave)

Two model catalysts, Au/TiO2/C (S) (sonochemically derived) and Au/TiO2/C (M) (microwave derived), were produced by employing ultrasound irradiation and microwave irradiation, respectively. The deposition of gold colloids onto the support powders, TiO2/C, was accomplished by using a solvated metal atom impregnation (SMAI) method. The SMAI technique provides highly-dispersed gold particles on the TiO2/C support. The catalytic performance of Au based catalysts 1 wt% Au-TiO2/C (S) and 1 wt%Au-TiO2(M)/C (M) have been tested for the oxidation of CO in the temperature range of 0-300 degrees C and compared to that of 1 wt% Au-TiO2 (Degussa-P25). A boost in the conversion of CO was observed for the sonochemically-derived catalyst, Au/TiO2/C (S), at low temperature. Hence, the reactivity order found for CO oxidation is (Au/TiO2/C (S)>Au/TiO2 (P25)>Au/TiO2/C (M)).     

基于紫外LED阵列光催化降解抗生素的研究

抗生素的大量使用对生态环境造成巨大的影响,光催化技术具有操作简单且无二次污染等特点被广泛应用于污染物的降解。在光催化降解抗生素过程中,光源对其降解效率至关重要,与传统的汞灯催化光源相比,紫外LED技术具有更高的能源效率及更低的功耗,使光催化工艺发生了巨大的变化。首先建立基于紫外LED阵列的光催化平台,采用光栅光谱仪和紫外照度计对LED阵列光源光谱特性及装置内光场分布进行测量分析。结果显示紫外LED光源波长介于265～295 nm之间,其主波长为275 nm,由于光场叠加效果,光照强度随着装置径向位置距离的增大而明显增大,装置轴向位置光照强度分布较为均匀;其次通过三维超景深显微镜、UV-Vis光谱测量技术对P25型光催化剂的粒子结构进行表征分析,同时使用半导体求导公式对TiO₂粉末进行禁带分析,结果显示TiO₂为球形,由于空气中相对湿度过大,水在TiO₂微粒表面的润湿性加强了微粒间的粘附力,因此有团聚现象产生,其禁带宽度为3.1 eV;最后以紫外LED阵列和高压汞灯为催化光源,P25型TiO₂为催化剂分别对甲基橙、磺胺类抗生素进行光催化降解,使用紫外-可见光分光光度计测量降解过程中的吸收光谱曲线,进而对抗生素降解率进行分析。结果表明,甲基橙和磺胺二甲嘧啶在紫外LED阵列为光源条件下均能够被降解,分别经过160和240 min的催化降解过程后,降解率分别达到70%和36%,符合一级动力学方程,经计算LED阵列光源与汞灯对甲基橙的降解动力学常数分别为-0.007 5和-0.113 5 min-1,对磺胺二甲嘧啶的降解动力学常数分别为-0.001 9和-0.019 4 min-1。因此对甲基橙和磺胺二甲嘧啶进行降解时,汞灯降解速率高于紫外LED阵列;由于紫外LED阵列和汞灯系统在催化降解污染物过程中功率和其与反应器中轴线距离不同,对两种光源的抗生素降解效率建立评价方法,即对紫外LED和汞灯以单位功率为标准进行距离降解效率分析,对于甲基橙,汞灯在单位功率下的距离降解效率高于紫外LED,但对于抗生素,紫外LED阵列的距离降解效率明显高于汞灯。依据以上各类光谱分析和应用结果,紫外LED阵列是一种有竞争力的光催化应用替代光源,此技术的广泛应用为抗生素的降解提供新途径。     

镶嵌Pt的二氧化钛纳米管的合成及其光催化性能研究

以金红石相二氧化钛(TiO₂)粉体为原料,采用水热法合成了二氧化钛纳米管(Titania nanotubes,简写为TNTs),然后把H₂PtCl₆的无水乙醇溶液引入到TNTs中,得到镶嵌Pt的二氧化钛纳米管(Pt/TNTs)。利用透射电镜(TEM)、X射线衍射(XRD)和紫外-可见光谱(UV-Vis)对产物进行了表征,并重点研究了Pt/TNTs的光催化性能。结果表明,有直径约为3 nm的 Pt纳米粒子插入到了TNTs中,且Pt粒子以Pt单质的形式存在。Pt/TNTs在可见光区域表现出较强的吸收,并且其起始吸收带边发生明显红移。紫外光催化降解甲基橙实验结果表明,金红石相TiO₂,TNTs和Pt/TNTs对甲基橙溶液的降解率分别达到46.8%, 57.2%和84.6%,Pt/TNTs的光催化活性较金红石相二氧化钛粉体和纯TNTs有显著的提高。     

四磺基酞菁锌敏化TiO2的原位自组装合成及可见光光催化

采用溶胶-凝胶法与原位合成相结合的方法,合成了2,9,16,23-四磺基酞菁锌(ZnfsPc)/TiO2复合材料,用FTIR,UV-Vis,XRD,Zeta电位、荧光光谱等对复合材料进行了表征,同时对材料进行了可见光光催化反应实验.实验结果表明采用该原位自组装的方法,不仅在TiO2颗粒表面原位生成酞菁,还在TiO2表面形成化学键(-SO2-O-Ti-).有效地增强了ZnTsPc的敏化能力,使光生载流子形成有效的分离,从而大幅度地提高了复合材料的可见光光催化能力.     

Comparison of catalytic activities for photocatalytic and sonocatalytic degradation of methylene blue in present of anatase TiO2-CNT catalysts

Anatase TiO(2)-CNT catalysts with high specific surface areas were prepared by depositing TiO(2) particles on the surface of carbon nanotubes (CNTs) using a modified sol-gel technique. These catalysts prepared with different amounts of CNTs were characterized by nitrogen adsorption, Fourier Transform infrared (FT-IR) spectroscopy, scanning electron microscope (SEM), Transmission Electron Microscope (TEM), X-ray diffraction (XRD), Raman spectroscopy, energy dispersive X-ray (EDX) and ultraviolet-visible (UV-Vis) spectroscopy. The catalytic activity of the anatase TiO(2)-CNT catalysts was assessed by examining the degradation of methylene blue (MB) from model aqueous solutions as a probe reaction under visible light and ultrasonic irradiation. The synergistic effect of the greater surface area and catalytic activities of the composite catalysts was examined in terms of the strong adsorption ability and interphase interaction by comparing the different amounts and roles of CNTs in the catalysts.     

Sonophotocatalytic degradation of methyl orange by nano-sized Ag/TiO2 particles in aqueous solutions

Sonophotocatalytic behaviour of methyl orange (MeO) in aqueous solution illuminated by light generated by a xenon lamp was investigated. For all three kinds of photocatalysts: Degussa P25 (75% anatase, 25% rutile, with a surface area of 55.07 m(2)/g), Yili TiO(2) (mainly anatase, with a surface area of 10.45 m(2)/g) and Ag/TiO(2) (silver loaded on Yili TiO(2)), the degradation followed pseudo-first order kinetics. The results showed a synergistic effect between sonolysis and photocatalysis. Some parameters affecting the sonophotocatalytic degradation of MeO with nanoparticles Ag/TiO(2) were determined. The results indicated that the degradation ratio of MeO increased with the increase of ultrasonic power. An optimum 60 mg/L of Ag/TiO(2) added to relatively low concentrations of MeO was proved to have the most effective degradation efficiency. The study on the effects of hydroxyl radical (*OH) scavengers (i.e. mannitol and dimethyl sulfoxide) on the MeO degradation indicated that *OH radicals played an important role during MeO degradation, which enhanced MeO to be completely decomposed.     

TiO2混晶光催化性能的第一性原理研究

本文采用第一性原理平面波超软赝势方法,通过搭建混晶界面的方式计算并分析了TiO2混晶的光催化性能.从光的吸收能力、光生电子-空穴对的分离效率以及载流子的转移效率三方面,与锐铁矿相和金红石相TiO2单晶进行对比分析.结果显示TiO2混晶的电子-空穴对分离率高于锐钛矿相TiO2、金红石相TiO2单晶,TiO2混晶中吸收峰明...     

Application of TiO2 with different structures in solar cells

The application of TiO2-based devices is mainly dependent on their crystalline structure,morphology,size,and exposed facets.Two kinds of TiO2 with different structures,namely TiO2 pompons and TiO2 nanotubes,have been prepared by the hydrothermal method.TiO2 with different structures is characterized by scanning electron microscopy(SEM),X-ray diffraction(XRD),and Brunauer-Emmett-Teller(BET) surface area analysis.Solar cells based on poly(3-hexylthiophene)(P3HT) and TiO2 with different structures are fabricated.In the device ITO/TiO2/P3HT/Au,the P3HT is designed to act as the electron donor,and TiO2 pompons and TiO2 nanotubes act as the electron acceptor.The effects of the TiO2 structure on the performance of hybrid heterojunction solar cells are investigated.The device with TiO2 pompons has an open circuit voltage(Voc) of 0.51 V,a short circuit current(Jsc) of 0.21 mA/cm2,and a fill factor(FF) of 28.3%.Another device with TiO2 nanotubes has a V oc of 0.5 V,J sc of 0.27mA/cm2,and FF of 28.4%.The results indicate that the TiO2 nanotubes with a unidimensional structure have better carrier transport and light absorption properties than TiO 2 pompons.Consequently,the solar cell based on TiO2 nanotubes has a better performance.     

Sonocatalytic degradation of methyl orange in the presence of TiO2 catalysts and catalytic activity comparison of rutile and anatase

Rutile and anatase titanium dioxide (TiO(2)) powders were used as sonocatalysts for the degradation of methyl orange which was used as a model compound. Ultrasound was used as an irradiation source. It was found that the sonocatalytic degradation ratios of methyl orange in the presence of TiO(2) powder were much better than ones without any TiO(2), but the sonocatalytic activity of rutile TiO(2) particles was obviously higher than that of anatase TiO(2) particles. Although there are many factors influencing sonocatalytic degradation of methyl orange, the experimental results show that the best degradation ratio of methyl orange can be obtained when the experimental conditions of the initial methyl orange concentration of 10 mg/l, rutile TiO(2) added amount of 500 mg/l, ultrasonic frequency of 40 kHz, output power of 50 W, pH=3.0 and 40 degrees C within 150 min were adopted. In addition, the catalytic activity of reused rutile TiO(2) catalyst was also studied and found to be better than new rutile TiO(2) catalyst sometimes. All experimental results indicated that the method of the sonocatalytic degradation of organic pollutants in the presence of TiO(2) powder was an advisable choice for treating non- or low-transparent organic wastewaters.     

模板合成法制备TiO2:Eu3+纳米管及其发光特性研究

以碳纳米管做模板,在不利用任何表面活性剂或催化剂情况下,通过溶剂热法成功合成均匀的TiO2:Eu3+纳米管。X射线衍射结果表明,该产物是TiO2的一种纯锐钛矿相。扫描电子显微镜及透射电子显微镜图像显示,所得到的TiO2:Eu3+纳米管在大小及分布上是均匀的,管壁的厚度约为8nm。提出了该纳米管可能的形成机制。发光光谱表明,由于5D0→7F2间的转换,TiO2:Eu3+纳米管会在612nm发出红光。此外,因为制备容易而且成本较低,这种合成路径还有望用来制备其他的一维无机纳米材料。     

Preparation of highly conductive CNTs/polyaniline composites through plasma pretreating and in-situ polymerization

In this study, carbon nanotubes (CNTs) were pretreated by plasma, and further in-situ polymerized with aniline to achieve uniform CNTs/polyaniline (PANI) composites with high conductivity. The highest conductivity (2.946 S/cm) of CNTs/PANI composites under optimum plasma treating parameters is much higher than those without CNTs pretreatment or premodified by acid oxidation method. The scanning electronic microscope (SEM) pictures indicate that smooth surfaces of pristine CNTs (diameter: 20-40 nm) changes into rough structures and the size increases to around 90 nm, which is further proved by the X-ray diffraction (XRD), the Fourier transform infrared spectroscopy (FTIR), and the Raman measurements. Thermogravimetric analysis (TGA) results reveal that the thermal stability of CNTs/PANI composite is better than that of pure PANI.     

TiO2柱撑蒙脱土的制备及其对品红降解的催化反应

基于TiO2光催化剂的优良光催化活性,采用酸性溶胶法合成了TiO2柱撑蒙脱土复合光催化剂,利用IR,UV-Vis,TG/DTA,XRD及SEM等手段对复合催化剂进行了表征,通过太阳光对酸性品红光催化降解实验,考察了催化剂的光催化活性。该催化剂比纳米TiO2对酸性品红的光催化降解反应表现出更高的催化活性,而且更易于沉降、回收。当TiO2柱撑蒙脱土光催化剂的用量为0.2 g.(100 mL)-1,酸性品红溶液的pH值为3时,在太阳光下40 min内酸性品红基本降解完全,而且该降解过程符合Langmuir-Hin-shelwood方程。X射线衍射(XRD)分析表明钛柱撑蒙脱土的层间距较钠基蒙脱土有明显的增大,紫外-可见吸收光谱表明TiO2柱撑蒙脱土比纳米TiO2具有更高的光吸收效率。     

模板合成法制备TiO2:Eu3+纳米管及其发光特性研究

以碳纳米管做模板,在不利用任何表面活性剂或催化剂情况下,通过溶剂热法成功合成均匀的TiO2:Eu3+纳米管。X射线衍射结果表明,该产物是TiO2的一种纯锐钛矿相。扫描电子显微镜及透射电子显微镜图像显示,所得到的TiO2:Eu3+纳米管在大小及分布上是均匀的,管壁的厚度约为8nm。提出了该纳米管可能的形成机制。发光光谱表明,由于5D0→7F2间的转换,TiO2:Eu3+纳米管会在612nm发出红光。此外,因为制备容易而且成本较低,这种合成路径还有望用来制备其他的一维无机纳米材料。     

Sonochemical synthesis of TiO(2 nanoparticles on graphene for use as photocatalyst

Using ultrasonication we succeed in a controlled incorporation of TiO(2) nanoparticles on the graphene layers homogeneously in a few hours. The average size of the TiO(2) nanoparticles was controlled at around 4-5 nm on the sheets without using any surfactant, which is attributed to the pyrolysis and condensation of the dissolved TiCl(4) into TiO(2) by ultrasonic waves. The photocatalytic activity of the resultant graphene-TiO(2) composites containing 25 wt.% TiO(2) is better than that of commercial pure TiO(2). This is partly due to the extremely small size of the TiO(2) nanoparticles and partly due to the graphene-TiO(2) composite structure consisting of homogeneous dispersion of crystalline TiO(2) nanoparticles on the graphene sheets. As the graphene in the composites has a very good contact with the TiO(2) nanoparticles it enhances the photo-electron conversion of TiO(2) by reducing the recombination of photo-generated electron-hole pairs.     

Degradation of nitrobenzene-containing wastewater by carbon nanotubes immobilized nanoscale zerovalent iron

Nanoscaled zerovalent iron (NZVI)–multiwalled carbon nanotubes (CNTs) composite materials were prepared by in situ reduction of Fe²⁺ onto CNTs for nitrobenzene (NB) degradation. The morphologies and the composites of the prepared materials were characterized by SEM, TEM, and XRD. The results showed that the agglomeration of NZVI decreased with NZVI dispersed well onto the surfaces of CNTs, the particle size of NZVI on CNTs was about 20–50 nm. The BET surface areas of NZVI–CNTs was about 95.8 m²/g, which was 39 % higher than that of bare NZVI. For storage, the prepared NZVI–CNTs were concentrated into slurry and stored in situ as fresh slurry without drying. Contrast experiment results showed that the removal efficiency of NB by NZVI–CNTs fresh slurry was 30 % higher than that of vacuum-dried NZVI–CNTs, which indicates that storing in situ as fresh slurry can be an alternative strategy for nanoparticle storage. Batch experiment results showed that NB could be degraded to aniline by NZVI–CNTs rapidly, and the appropriate pH can be conducted at a relatively wide range from 2.0 to 9.0. The optimum mass ratio of iron–carbon was 1:1, and removal efficiency of NB by NZVI–CNTs with this mass ratio can achieve 100 % within 1 min. The degradation process of NB to intermediates was accelerated significantly by NZVI–CNTs, however, there was still a long term for the intermediates to transfer completely into the final product of aniline. The existence of CNTs can improve the formation of aniline through accelerating the electron transfer by forming microscopic galvanic cells with NZVI.     

空气电极/AC作载体对TiO2光催化性能的影响

研究了空气电极和活性碳 (AC)作载体对TiO2 光催化氧化活性艳红 (K 2BP)性能的影响 .实验结果表明 ,用空气电极 /AC作载体能显著提高TiO2 的光催化反应速度 ;空气电极不仅具有良好的合成H2 O2 的性能 ,而且对TiO2 光催化剂可产生大约 +0 .5V的偏压作用 ,大大减小了TiO2 光生电荷的复合几率 ;AC对有机物分子良好的吸附作用提高了有机物分子在TiO2 表面及周围的富集浓度 ,其含量在 2 1%左右可使光催化剂达到最佳的催化效果 .复合电极工作电流密度对活性艳红的氧化脱色速度有影响 ,i=15mA/cm2 ,速度达到最大 ;活性艳红分子在复合电极表面的吸附受溶液pH值的影响 ;提出了复合电极的工作原理 .