溶胶凝胶法制备TiO_2-Ag的介孔微球及其抗菌性能研究

以钛酸丁酯和硝酸银分别作为钛源、银源,聚乙二醇系为扩孔剂,采用溶胶凝胶法制备TiO_2-Ag介孔微球。通过调节煅烧温度优化煅烧工艺,并通过热场发射扫描电子显微镜(EDS/EBSD)、X射线衍射仪(XRD)、傅里叶红外光谱仪(FT-IR)及比表面积及孔体积测量仪(BET)等对所得产物的形貌、晶体结构、化学组成和比表面积等进行分析。采用震荡法来评定TiO_2-Ag介孔微球的抗菌性。研究表明:采用溶胶凝胶法制备的TiO_2-Ag介孔微球,其Ag粒子在TiO_2表面均匀分布;在煅烧温度为500℃下添加扩孔剂,能有效提高TiO_2-Ag介孔微球的比表面积,增大TiO_2-Ag吸附能力;TiO_2-Ag介孔微球具有良好的抗菌性能。     

TiO_2-石墨烯电极光电催化处理罗丹明B的研究

通过溶胶凝胶法制备介孔TiO_2-石墨烯复合薄膜,对该薄膜做扫描电镜,紫外-可见漫发射透射光谱,X-射线光谱等表征.结果表明:制备的介孔TiO_2-石墨烯复合薄膜中TiO_2以锐钛矿晶型存在,石墨烯的掺杂使其对光的吸收增强.对该薄膜的光电流密度测试结果表明石墨烯掺杂后光电流密度显著提高.在光电催化降解罗丹明B的实验中,由于掺杂其中的石墨烯起到了分离光生电子和空穴的作用,与单纯的介孔TiO_2薄膜相比,反应动力学常数提高了1. 6倍.     

SiO_2/TiO_2复合材料的制备及其光催化性能

首先以P123(EO_(20)PO_(70)EO_(20))和PEG(聚乙二醇)为复合模板,制备了短棒状介孔SiO_2,然后采用电子转移催化剂再生-原子转移自由基聚合(ARGET ATRP)方法对其进行改性。以改性后的SiO_2为模板,以钛酸四丁酯(TBT)为钛源,制备了带有TiO_2壳的短棒状介孔SiO_2/TiO_2光催化剂复合材料。采用热重分析(TGA)、透射电子显微镜(TEM)、X射线衍射分析(XRD)、比表面和空隙分析仪对其进行了表征,通过甲基橙光降解反应研究了其光催化性能。结果表明:亲水性聚合物成功改性介孔SiO_2;锐钛矿相的TiO_2纳米粒子均匀分散在SiO_2表面;制得的SiO_2/TiO_2复合材料具有双峰孔结构;在可见光照射下,4.5 h后对甲基橙的降解率最高可达到99.5%,具有较高的光催化效率。     

介孔二氧化钛微球的制备

以F127(PEO_(106)PPO_(70)PEO_(106))为模板剂,甲酸,质量分数为36%的盐酸,钛酸四丁酯为前驱体,通过溶剂挥发法制备了TiO_2纳米粒子。对纳米粒子的晶型、形貌以及孔径尺寸等进行了表征。结果表明,制备的TiO_2为锐钛矿型,具有介孔的球型结构,微球直径20~40nm,分散性良好,而且随着模板剂F127的用量增加,其孔径和比表面积都有所增加;当F127、甲酸、盐酸和TBOT用量分别是2.0g、1.97、2.03和3.40mL时,制备的介孔TiO_2纳米微球的平均孔径达12.94nm,比表面积达100.03m~2/g。     

NaCl修饰SnO_2/钙钛矿界面的高效钙钛矿太阳能电池

钛矿太阳能电池(PSC)通常由电子传输层(ETL)、钙钛矿光吸收层和空穴传输层组成,而电子传输层/钙钛矿层和钙钛矿层/空穴传输层的界面对钙钛矿薄膜的性质及太阳能电池的性能有较大影响。通过简单的旋涂法,在SnO_2电子传输层上旋涂一层NaCl层,来修饰SnO_2电子传输层与MAPbI_3钙钛矿光吸收层之间的界面。结果表明:NaCl修饰层不仅能提供部分Na~+和Cl~-溶解在钙钛矿前驱体中,辅助钙钛矿结晶,增大钙钛矿晶粒尺寸,而且NaCl能同时与MAPbI_3钙钛矿层和SnO_2电子传输层作用形成Pb—Cl和Sn—Cl键,使界面的化学结合增强,降低界面缺陷态,增强载流子的寿命和传输效率。此外,NaCl修饰层显著降低了电子传输层的功函数,使制得的器件开路电压高达1.141V,太阳能电池最终获得了高达19.49%的光电转换效率。     

介孔TiO2负载纳米铁催化剂的制备及降解特性

以聚乙二醇4000(PEG-4000)为致孔剂,采用溶胶-凝胶法制备出了光催化活性高的锐钛矿型介孔Ti O2;以制备的介孔Ti O2为载体,采用液相还原法,在介孔Ti O2孔道及表面原位生成纳米铁以制备出介孔Ti O2负载纳米铁催化剂,并用XRD、BET进行了表征.以酸性红B染料为降解对象,研究了不同煅烧温度对介孔Ti O2光催化性能的影响.通过介孔Ti O2负载纳米铁催化剂与等当量的介孔Ti O2、纳米铁以及介孔Ti O2-纳米铁机械混合的光催化降解实验的比较,结果表明:该复合催化剂的光催化降解效率远高于介孔Ti O2、纳米铁以及介孔Ti O2-纳米铁机械混合催化剂的降解效率,20,min就可以使酸性红B的降解率达到85%.     

AgI负载纳米介孔TiO2的制备及其光降解性能

研究了AgI负载纳米介孔TiO_2的制备及其光降解性能。以钛酸丁酯为钛源,P123为模板剂,采用软膜板法制备了AgI负载型纳米介孔TiO_2。利用N_2吸附-脱附实验、紫外-可见光谱、X-射线衍射、X射线光电子能谱分析等技术对材料进行了结构表征。通过以甲基橙溶液为模拟污染物,用所得样品进行光降解实验。结果表明:TiO_2负载了AgI之后光降解性能有明显的提升,达到了材料改性的目的。     

介孔TiO_2负载纳米铁催化剂的制备及降解特性

以聚乙二醇4000(PEG-4000)为致孔剂,采用溶胶-凝胶法制备出了光催化活性高的锐钛矿型介孔Ti O2;以制备的介孔Ti O2为载体,采用液相还原法,在介孔Ti O2孔道及表面原位生成纳米铁以制备出介孔Ti O2负载纳米铁催化剂,并用XRD、BET进行了表征.以酸性红B染料为降解对象,研究了不同煅烧温度对介孔Ti O2光催化性能的影响.通过介孔Ti O2负载纳米铁催化剂与等当量的介孔Ti O2、纳米铁以及介孔Ti O2-纳米铁机械混合的光催化降解实验的比较,结果表明:该复合催化剂的光催化降解效率远高于介孔Ti O2、纳米铁以及介孔Ti O2-纳米铁机械混合催化剂的降解效率,20,min就可以使酸性红B的降解率达到85%.     

多级孔Ni_2P/TiO_2-Al_2O_3催化加氢脱萘工艺条件优化

制备了多级孔TiO_2-Al_2O_3载体和Ni_2P/TiO_2-Al_2O_3催化剂,将该催化剂与负载Ni_2P/介孔Al_2O_3和Ni_2P/γ-Al_2O_3进行了催化性能对比。分别用正交设计法和单因素考察法,对反应温度、氢油体积比、质量空速和反应压力等工艺条件对反应结果的影响进行了考察,并得出了优化后的工艺条件。结果表明,Ni_2P/TiO_2-Al_2O_3较Ni_2P/γ-Al_2O_3和Ni_2P/介孔Al_2O_3的催化活性和选择性都高;以多级孔Ni_2P/TiO_2-Al_2O_3为催化剂时,萘的转化率和十氢萘选择性受反应压力和温度影响较大,受氢油体积比和空速的影响较小。多级孔Ni_2P/TiO_2-Al_2O_3催化剂在加氢脱萘反应中的最佳反应条件为:反应温度300℃,反应压力4 MPa,氢油体积比500,质量空速1 h-1,此时萘的转化率和十氢萘选择性分别为99.2%和72.0%。     

水热法制备TiO_2致密层及其在钙钛矿太阳电池中的应用

通过水热法在180℃下制备了三种不同厚度的TiO_2致密层并成功应用于钙钛矿太阳电池。通过场发射扫描电镜(SEM)、X射线衍射(XRD)和透射电镜(TEM)对TiO_2致密层的形貌、成分及晶型进行表征,并利用电流-电压(I-V)特性曲线和电化学阻抗谱(EIS)研究了TiO_2致密层的厚度对钙钛矿太阳电池光电性能的影响。研究表明:随着TiO_2致密层厚度的增加,钙钛矿太阳电池的转换效率先增加后降低,在厚度为300nm时转换效率较高,为3.31%。     

碳对电极CsPbBr3 钙钛矿太阳能电池的 制备及其光、热稳定性研究

采用两步溶液法制备了无机钙钛矿Cs Pb Br3薄膜,通过增加Pb Br2薄膜在Cs Br甲醇溶液中的反应时间来增加钙钛矿薄膜的厚度并改善薄膜的结晶性,从而提高了无机钙钛矿太阳能电池的光电转换效率。当反应时间从30 min提升至90 min时,电池的效率从1.43%上升至2.84%,这得益于光电流密度得到有效提高。所制备的钙钛矿太阳能电池表现出良好的热稳定性和光稳定性。在最大功率点条件下,全光谱太阳光(AM 1.5,100 m W/cm2)持续照射1 h后,其工作性能保持稳定。在100?C条件下持续加热476 h,电池的效率仍保持在初始效率之上。     

Morphology and conductivity of in-situ PEO-LiClO4-TiO2 composite polymer electrolyte

PEO-LiClO4-TiO2 composite polymer electrolyte films were prepared. TiO2 was formed directly in matrix by hydrolysis and condensation reaction of tetrabutyl titanate. The crystallinity, morphology and ionic conductivity of composite polymer electrolyte films were examined by differential scanning calorimetry, scanning electron microscopy, atom force microscopy and alternating current impedance spectroscopy, respectively. The glass transition temperature and the crystallinity of composite polymer electrolytes are decreased compared with those of PEO-LiClO4 polymer electrolyte film. The results show that TiO2 particles are uniformly dispersed in PEO-LiClO4-5%TiO2 composite polymer electrolyte film. The maximal conductivity of 5.5×10^-5 S/cm at 20℃ of PEO-LiClO4-TiO2 film is obtained at 5% mass fraction of TiO2.     

Mechanism and behaviors of Cr3+-doped TiO2

TiO₂ powder and TiO₂ thin film on the surface of glazed ceramic tile were prepared by sol-gel method. The influences of different doping Cr³⁺ concentration on the photocatalytic activity of TiO₂ were discussed, UV-visible and X-ray diffraction analysis were used to test the performance of TiO₂ powder and film. The results indicate that photocatalytic activity of doping Cr³⁺-TiO₂ thin film is higher than that of powder, and the interaction between Cr³⁺-doped and substrate can greatly enhance the photocatalytic activity. The results of X-ray diffraction and photoabsorption show that the Cr³⁺-doped energy level in TiO₂ is 0.62 eV high from the top of valence band, which belongs to the type of deep energy level doping. On the basis of the semiconductor energy level theory and Cr³⁺ dopant energy level, the semiconductor energy level model of Cr³⁺ in TiO₂ powder and thin film were established, and the doping mechanisms of Cr³⁺-doped in TiO₂ powder and thin film were analyzed. Foundation item: Project (20466001) supported by the National Natural Science Foundation of China     

Self-cleaning glass coated with Fe^3＋ -TiO2 thin film

The self-cleaning glass coated with Fe^3 -TiO2 photocatalytic thin film was prepared by sol-gel process from the system Ti(OC4H9),-NH(C2H4OH)2-C2H5OH-H2O containing FeCl3. The microstructure and properties of the film were studied using differential thermal analysis-thermogravimetry(DTA-TG), X-ray diffration (XRD) and scanning electron microscope(SEM). The transmittance of the self-cleaning glass was measured by using UV-Vis spectrometer. The effects of content of Fe^3 and the thickness of Fe^3 -TiO2 thin film on the photocatalytic ac-tivity were examined. The results show that the photocatalytic thin films are mainly composed of Fe3O4 and TiO2 particles within 10-100 nm. The appropriate amount of Fe^3 is effective for improving the photocatalytic activities of TiO2. The best photocatalytic activity is obtained when the molar ratio of Fe^3 to TiO2 is 0. 005 and the glass is coated with 9 layers.     

Investigation on plasma-sprayed ZrO2 thermal barrier coating on nickel alloy substrate

The thermal barrier coatings with NiCrAlY alloy bonding layer, NiCrAlY-Y₂O₃ stabilized ZrO₂ transition layer and Y₂O₃ stabilized ZrO₂ ceramic layer are prepared on nickel alloy substrates using the plasma spray technique. The relationship among the composition, structure and property of the coatings are investigated by means of optical microscope, scanning electronic microscope and the experiments of thermal shock resistance cycling and high temperature oxidation resistance. The results show that the structure design of introducing a transition layer between Ni alloy substrate and ZrO₂ ceramic coating guarantees the high quality and properties of the coatings; ZrO₂ coatings doped with a little SiO₂ possesses better thermal shock resistance and more excellent hot corrosion resistance as compared with ZrO₂ coating materials without SiO₂; the improvement in performance of ZrO₂ coating doped with SiO₂ is due to forming more dense coating structure by self- closing effects of the flaws and pores in the ZrO₂ coatings. Biography of the first author: LU An-xian, Ph.D, professor, born in Jan. 1960, majoring in inorganic non-metal materials.     

Local segregation in Cu-In precursors and its effects on microstructures of selenized CuInSe2 thin films

Local segregation in Cu-In precursors and its effects on the element distribution and microstructures of selenized CuInSe₂ thin films were investigated. Cu-In precursors with an ideal total mole ratio of Cu to In of 0.92 were prepared by middle frequency alternating current magnetron sputtering with Cu-In alloy target, then CuInSe₂ absorbers for solar cells were formed by selenization process in selenium atmosphere. Scanning electron microscope and energy dispersive X-ray spectroscope were used respectively to observe the surface morphologies and determine the compositions of both Cu-In precursors and CuInSe₂ thin films. Their microstructures were characterized by X-ray diffractometry and Raman spectroscope. The results show that Cu-In precursors are mainly composed of Cu₁₁In₉ phase with In-rich solid solution. Stoichiometric CuInSe₂ thin films with a homogeneous element distribution and single chalcopyrite phase can be synthesized from a segregated Cu-In precursor film with an ideal total mole ratio of Cu to In of 0.92. CuInSe₂ thin film shows P-type conductivity and its resistivity reaches 1.2×10³ Θ·cm. Foundation item: Project(2004AA513023) supported by the National High Technology Research and Development Program of China     

Preparation of TiO2 Thin Film and Its Antibacterial Activity

TiO2 nanometer thin films with photocatalytic antibacterial activity were prepared by the sol-gel method on fused quartz and soda lime glass precoated with a SiO2 layer. The thin films were characterized by X-ray photoelectron spectroscopy ( XPS ), scanning electron microscopy (SEM), and X- ray diffraction ( XRD ). The results show that sodium and calcium diffusion into nascent TiO2 film is effectively retarded by the SiO2 layer precoated on the soda lime glass, The antibacterial activity of the films was determined. The crystalline of TiO2 nanometer thin film has important effects on the antibacterial activity of the film.     

Using HF rather than NH4F as doping source for spray-deposited SnO2:F thin films

Fluorine doped tin oxide SnO₂:F thin films were prepared by the spray pyrolysis (SP) technique on glass substrates by using SnCl₂·2H₂O as a precursor and NH4F and HF as doping compounds. A comparison between the properties of the films obtained by using the two doping compounds was performed by using I–V characteristics in the dark at room temperature, AC measurements, and transmittance. It is found that the films prepared by using HF have smaller resistivity, lower impedance and they are less capacitive than films prepared by using NH₄F. In addition, these films have higher transmittance, higher optical bandgap energy and narrower Urbach tail width. These results are interesting for the use of SnO₂:F as forecontact in CdS/CdTe solar cells.     

Effects of nucleating additives on crystallization and properties of CaO-B2O3-SiO2 glass-ceramics

ZrO₂, TiO₂ and P₂O₅ were doped in CaO-B₂O₃-SiO₂ glass-ceramics as nucleating additives. Effects of different nucleating additives on the phase separation and crystalline behaviors were investigated by using gradient temperature furnace, DTA and XRD. Then, sintering process of the glass-ceramics was investigated by testing sintering shrinkage, dielectric constant and loss. The experimental results shows that the glass-ceramics doped with nucleating additives represents higher crystallization, with ZrO₂ as an exceptional effective dopant to promote the precipitation of wollastonite crystal. Finally, ZrO₂ containing glass-ceramics was chosen to study the influence of sintering temperature and soaking time with the help of X-ray diffraction analysis and density measurement. The glass-ceramics can be well consolidated at 850 °C for 10 min, with low dielectric constant (5.87) and loss (3.21 × 10⁻⁴), which is desirable for LTCC application.     

Preparation of TiO2 photocatalyst loaded with V2O5 for O2 evolution

TiO₂ photocatalysts loaded with V₂O₅ were prepared via a modified hydrolysis process, and characterized by X-ray diffraction, transmission electron microscopy, Raman spectra and diffuse reflectance UV-Vis spectra measurements. The photocatalytic activity of V₂O₅/TiO₂ was investigated by employing splitting of water for O₂ evolution. The results indicate that V₂O₅ loading can pronouncedly improve the photocatalytic activity of TiO₂ with Fe³⁺ as an electron acceptor under UV or visible light irradiation. The optimum mass fraction of the loaded V₂O₅ is 8%, and the largest speed of O₂ evolution for 8%V₂O₅ (mass fraction) loaded TiO₂ catalyst is 118.2 μmol/(L·h) under UV irradiation, and 83.7 μmol/(L·h) under visible light irradiation.