具有可见光响应的改性纳米TiO2研究进展

通过改性可以改变TiO₂只有在紫外光激发下才显示出较高光催化效率的特点,使其在可见光范围也显示出较高的活性。本文综述了纳米TiO₂改性方面的研究进展,指出通过元素掺杂、贵金属修饰、聚合物修饰、半导体复合、染料敏化等手段对TiO₂进行改性,可以减小纳米TiO₂禁带,提高纳米TiO₂对可见光的响应性和量子效率。分析认为,实验室制备的改性纳米TiO₂可见光光催化效果已经比较理想,解决回收难、工程易操作性等问题是未来的发展方向。     

TiO2/ML-Ti3C2复合纳米材料的制备及其光催化性能

通过水热技术在二维(2D)多层材料Ti_3C_2 (multi-layer Ti_3C_2, ML-Ti_3C_2)的表面及层间原位晶化和生长锐钛矿相TiO_2纳米球,制备出TiO_2/ML-Ti_3C_2复合纳米材料。采用XRD、SEM、氮吸附等表征技术对TiO_2/ML-Ti_3C_2纳米复合材料进行分析表征,并以亚甲基蓝(MB)为模拟污染物,对纯TiO_2和TiO_2/ML-Ti_3C_2复合纳米材料的光催化性能进行了评价。实验结果表明,两种材料的耦合抑制了Ti O_2中光生电子-空穴对的湮灭,延长了复合光催化剂中载流子寿命,拓宽了复合材料的光谱响应范围。在紫外光照射下,以TiO_2/ML-Ti_3C_2复合纳米材料为光催化剂,200 mg/L的MB溶液在20 min内几乎完全脱色,降解率为98.98%。TiO_2/ML-Ti_3C_2纳米复合材料的光催化性能优于纯TiO_2和Ti_3C_2, Ti_3C_2优异的电子传输能力和超强的吸附性能优化了TiO_2的光催化性能。本研究为使用光催化技术处理废水提供了一种新的思路,具有一定的实际应用前景。     

LiNi0.4Co0.2Mn0.4O2与LiMn2O4共混正极材料电化学性能

为开发具有优良循环性能和安全性能的大型锂离子电池的正极材料,将不同比例的LiNi_(0.4)Co_(0.2)Mn_(0.4)O_2和Li Mn2O4材料进行共混,研究了LiNi_(0.4)Co_(0.2)Mn_(0.4)O_2和Li Mn2O4共混以及共混比例(10∶0、8∶2、7∶3、6∶4、5∶5、0∶10)对锂离子电池的首次放电性能、循环性能和倍率性能以及交流阻抗和循环伏安曲线的影响,并采用扫描电镜对电极材料进行了表征.研究结果表明,共混比例会影响材料的电化学性能,8∶2,7∶3和6∶4配比的混合材料的体积比容量、循环性能和倍率性能要好于纯LiNi_(0.4)Co_(0.2)Mn_(0.4)O_2和Li Mn2O4材料.其中,8∶2配比的材料性能最好.     

纳米CuFe2O4活化过一硫酸盐降解诺氟沙星性能

为研究使用过一硫酸盐(PMS)的高级氧化技术去除水体中微量有机污染物的高效可行方法,通过柠檬酸辅助溶胶-凝胶法制备纳米CuFe_2O_4材料,以其为非均相催化剂,探究CuFe_2O_4/PMS体系对诺氟沙星(NFX)的降解性能.采用X射线衍射仪、电子透射显微镜、BET手段对材料进行表征,考察煅烧温度对纳米CuFe_2O_4结构及催化性能的影响,并试验纳米CuFe_2O_4的重复使用性和稳定性.探讨纳米CuFe_2O_4投加量、PMS浓度、溶液初始pH对CuFe_2O_4/PMS体系降解NFX性能的影响,并探究该体系的氧化活性物种及降解机理.结果表明:制备纳米CuFe_2O_4的最佳煅烧温度为400℃,该温度下纳米CuFe_2O_4晶型较好,比表面积较大,且表现出较高的催化活性;在纳米CuFe_2O_4/PMS体系中,控制NFX初始质量浓度为5 mg/L,最适宜的反应条件为:纳米CuFe_2O_4投加量为0.1 g/L、PMS浓度为0.5 mmol/L、初始溶液pH为9.5,该条件下反应30 min后NFX的去除率高达99%;纳米CuFe_2O_4能有效活化PMS生成·OH和SO_4~-·,SO_4~-·是实现NFX快速降解的主要活性物种.     

海洋防污用新型TiO2/氟化丙烯酸纳米复合涂料的研制

合成了一种Ti O_2/氟化丙烯酸纳米复合涂料,对树脂和合成产物进行了一系列的检测。采用凝胶渗透色谱法和差示扫描量热法分别检测氟化丙烯酸树脂的重均分子量和玻璃化转变温度,红外光谱检测确认了纳米Ti O_2在树脂上的成功接枝,海洋浸没实验分析了复合涂层的防污程度。实验结果显示,通过添加表面改性的纳米Ti O_2能够显著提高氟化丙烯酸聚合物的防污性能,从而提供了一种无毒、环保的海洋防污涂料制备方法。     

Fe2(SO4)3对活性污泥微生物活性的影响

为了解Fe₂(SO₄)₃作为絮凝剂对活性污泥中微生物活性的影响,向活性污泥系统中投加质量浓度为20、40、60、80,100 mg·L-1的Fe₂(SO₄)₃,反应4 h后测定活性污泥的脱氢酶活性、比耗氧速率(R_SOU)、胞外聚合物(EPS)及各组分含量,同时测定系统出水的COD等各项指标．结果表明:Fe₂(SO₄)₃质量浓度在20～60 mg·L-1时对活性污泥的脱氢酶活性、R_SOUEPS及各组分含量影响均不大,此时污水中COD、TP、UV₂₅₄等污染物随Fe₂(SO₄)₃质量浓度增加而有较大幅度去除．Fe₂(SO₄)₃质量浓度为80 mg·L-1时,污泥的脱氢酶活性、R_SOU、总EPS含量均明显下降．当Fe₂(SO₄)₃质量浓度增加到100 mg·L-1时,污泥的脱氢酶活性、R_SOU进一步受到抑制,而总EPS含量则大幅度提升．此时污水中COD、TP、UV₂₅₄等污染物去除率增加幅度变缓,SCOD及NH₃-N去除作用有所下降．     

GO/CoFe2O4催化过硫酸盐降解邻苯二甲酸二丁酯效能

为高效地去除水中环境激素类污染物,采用共沉淀法合成了氧化石墨烯负载钴尖晶石铁氧体(GO/CoFe_2O_4)催化剂,催化过硫酸盐(PMS)去除水中邻苯二甲酸二丁酯(DBP).采用SEM、TEM、XPS、XRD对催化剂进行表征,研究不同条件下催化PMS去除水中DBP的效果,提出催化PMS反应机理.结果表明,GO/CoFe_2O_4为颗粒状尖晶石结构,室温下,DBP初始浓度为2μmol/L、催化剂投量为0.1 g/L、PMS浓度为20μmol/L、pH为7时,GO/CoFe_2O_4催化PMS体系对DBP的去除率可达89%,使用5次后催化效果仅降低5%.该新型复合催化剂高效、具有磁性、方便回收,具有良好的工程应用前景.     

基于双金属MOFs 制备Co3O4/In2O3 复合物及其气敏性能的研究

以硝酸铟(In(NO₃)₃·xH₂O)、对苯二甲酸(H₂BDC)、六水合硝酸钴(Co(NO₃)· 6H₂O) 为原料, 首先采用一锅油浴法合成了含有Co²⁺ 的铟基金属有机框架材料(MOFs) Co²⁺/CPP-3(In) 材料, 然后在450 ℃ 下焙烧制备Co₃O₄/In₂O₃ 复合物气敏材料, 将Co₃O₄/In₂O₃ 复合物的粉体制作成传感器, 并对其气敏性能进行研究。利用扫描电子显微镜和X 射线衍射仪(XRD) 对双金属MOFs Co²⁺/CPP-3(In) 材料和Co₃O₄/In₂O₃ 复合物进行表征, 采用静态配气法测试其气敏性能。结果表明, Co₃O₄/In₂O₃(n_Co : n_In = 0.4 : 1) 样品的形貌保留了其MOFs 前驱体的棒状结构, 棱柱形框架更为突出, 表面呈凹陷状, 棒体中间粗两边细, 六角截面和棒体均布满了孔洞。结合EDX 和XRD 表征结果, Co²⁺/CPP-3(In) MOFs 前驱体完全转化成Co₃O₄/In₂O₃ 复合物; Co₃O₄/In₂O₃(n_Co : n_In = 0.4 : 1) 复合物在 70 ℃ 下对5×10^-6 H₂S 的气敏性能最优, 响应值达到153, 是同条件下纯备In₂O₃对H₂S 响应值的5 倍, 并且有较好的重复性、选择性和稳定性。     

纳米Al2O3改性环氧胶黏剂和钢铁附着机理的研究

通过拉拔法测定纳米Al₂O₃改性环氧胶黏剂和钢铁之间的附着强度,并结合环氧胶的表面能参数测定以及X射线光电子能谱(XPS)分析,对纳米Al₂O₃提高环氧胶和钢铁附着力的机理进行研究.表面能测定结果表明,添加纳米Al₂O₃使环氧胶的极性增加;XPS能谱分析结果表明,当纳米Al₂O₃质量分数达到2%时,环氧胶中形成新的羧基极性基团;进一步研究发现,当纳米Al₂O₃质量分数为1%时未形成新的羧基基团,当纳米Al₂O₃质量分数为8%时单位接触面积上新的羧基基团的数目较2%时少,这与附着强度的变化规律是一致的.因此,纳米Al₂O₃改性的环氧胶黏剂与钢铁的附着强度的增强是由于Al₂O₃与环氧胶的相互作用形成了新的羧基极性基团．     

SO2-4对块体纳米晶铜阳极极化行为的影响

为了揭示SO₂^-4对块体纳米晶铜耐蚀性能的影响规律,利用电化学方法,结合X射线衍射、能谱分析、扫描电镜等表面分析技术,研究了惰性气体沉积原位温压法制备的块体纳米晶铜在不同质量分数（0.3%、1.3%、2.3%、3.3%和4.3%）Na₂SO₄溶液中的阳极极化行为.结果表明,随着SO₂^-4的增多,纳米晶铜的致钝电流密度增大,而致钝电位降低.在0.3%的Na₂SO₄溶液中加入1%的NaCl,纳米晶铜阳极极化行为发生明显变化,Cl^-在纳米晶铜表面形成难溶于水的CuCl保护钝化膜,纳米晶铜致钝电流密度降低,活化-钝化过渡区电流密度下降速率显著减小.     

Preparation and properties of SrBi2.2 Ta2O9 thin film

SrBi_2.2 Ta₂O₉ (SBT) thin film with thickness of 2 μm was successfully prepared by sol-gel method, using strontium acetate semihydrate [Sr(CH₃ COO)₂ · 1/2H₂O] and bismth subnitrate [BiO(NO₃)], and tantalum ethoxide [Ta(OCH₂CH₃)₅] as source materials, glacial acetic and ethylene glycol as solvents. The X-ray diffraction (XRD) and transmission electron microscope(TEM) results indicate that SBT layer-perovskite phase obtained has to be single phase, SBT thin film is formed after being annealed at 800 °C for for 1 min. The typical hysteresis loop of SBT thin film on Pt/Ti/SiO₂/Si is obtained, and the measured polarization value of the SBT thin film is 4. 2 μ/C/cm². Foundation item: Project (HIT. 2001. 67) supported by the Scientific Research Foundation of Harbin Institute of Technology; project (50172012) supported by the National Natural Science Foundation of China     

Preparation and characterization of nanocrystalline SnO2 thin film by electrodeposition technique

A novel process for preparing tin oxide thin films directly on copper foil by electrodeposition was developed. An optimal preparation technology to obtain SnO2 thin films was proposed with current density of 8 mA/cm2, the time of deposition of 120 min, the concentration of tin dichloride of 0.02 mol/L and the concentration of dissociated acid of 0.03 mol/L. The phase identification, microstructure and morphology of the thin films were investigated by thermogravimetric analysis and differential thermal analysis, X-ray diffraction, Fourier transform infrared spectra,scanning electron microscopy and transmission electron microscopy. The as-deposited thin film was composed of SnO2·xH2O was obtained by drying at room temperature. Nanocrystalline SnO2 thin film having tetragonal structure with average grain size in the range of 8 to 20 nm and porous, uniform surface was obtained by heat-treating the as-deposited film at 400 ℃ for 2 h. Electrochemical characterization shows that SnO2 film can deliver a discharge capacity of 798 mAh/g and the SnO2 film with smooth surface and annealed at 400 ℃ for 2 h has better cycle performance than that with rough surface and annealed at 150 ℃ for 10 h.     

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.     

基于VO2热相变的光子晶体波导开关

基于相变材料VO₂,设计了一款光子晶体波导结构的光开关。通过在硅波导中填充SU-8包层对温度灵敏度做补偿,降低了波导开关的温度敏感特性。采用热驱动开关实现了1591 nm波长处约9.5 dB的消光比。同时提出一种新型级联波导来优化开关结构,实现了27.46 dB的消光比。     

Preparation and electrical properties of BaPbO3 thin film

BaPbO3 thin films were deposited on Al2O3 substrates by sol-gel spin-coating and rapid thermal annealing. The microstructure and phase of BaPbO3 thin films were determined by X-ray diffractometry, scanning electrons microscopy and energy dispersive X-ray spectrometry. The influence of annealing temperature and annealing time on sheet resistance of the thin films was investigated. The results show that heat treatment, including annealing temperature and time, causes notable change in molar ratio of Pb to Ba, resulting in the variations of sheet resistance. The variation of electrical properties demonstrates that the surface state of the film changes from two-dimensional behavior to three-dimensional behavior with the increase of film thickness. Crack-free BaPbO3 thin films with grain size of 90 nm can be obtained by a rapid thermal annealing at 700 ℃ for 10 min. And the BaPbO3 films with a thickness of 2.5 μm has a sheet resistance of 35 Ω·-1.     

Na_2SO_4掺杂含MgO铝酸钙熟料矿相转变及稳定性能

为了系统研究升温制度、降温制度、烧结温度和烧结时间对Na2SO4掺杂含MgO铝酸钙熟料的物相转变及化学稳定性能的影响规律,以MgO、CaCO_3、SiO_2、Al_2O_3和Na_2SO_4为原料,采用高温烧结和Na_2CO_3溶液标准溶出方法进行相关研究.结果表明,快速升温能抑制硫元素的挥发,促进11CaO·7Al_2O_3·CaS的生成.快速降温有利于11CaO·7Al_2O_3·CaS的稳定存在,从而强化熟料中氧化铝的浸出性能.在最佳烧结条件下烧结温度为1 350℃,烧结时间为30 min,升温速度和降温速度均为15℃·min-1,此时熟料的物相为11CaO·7Al_2O_3·CaS和2CaO·SiO_2.     

染料敏化太阳能电池光阳极TiO_2致密膜的制备

用溶胶-凝胶法在染料敏化太阳能电池的FTO导电玻璃与多孔薄膜之间制备了一层TiO2致密膜,采用AFM、XRD、UV-Vis以及接触角测定仪等对其进行表征。结果表明,制备的薄膜结构致密、透明,晶粒细小均匀;水接触角从FTO表面的54.425°下降到致密膜表面的33.763°,有利印刷浆料润湿结合;对比实验证实了TiO2致密膜的引入,隔离了液体电解质与FTO导电玻璃的直接接触,减小电池的暗电流,电池的电流密度及光电转化效率分别提高了17.7%和22.4%。     

纳米TiO2的沉淀法制备及表征

用廉价的TiCl4作原料,采用简单易行的沉淀法制备出了平均粒径为20nm的锐铁矿型纳米TiO2粉体,确定了最佳煅烧温度为500℃.XRD结果表明,400℃煅烧后的产物为锐铁矿型纳米TiO2,在600℃煅烧后的产物仍保持锐铁矿晶型,而在700℃煅烧后的产物才开始出现金红石型TiO2,但粉体的主要晶型仍为锐铁矿型.     

Inducing effect of Pb(Zr0.4Ti0.6)O3 thin film derived by different processes in BiFeO3/Pb(Zr0.4Ti0.6)O3 multilayer capacitor at room temperature

BiFeO₃/PZT multilayer capacitor was prepared on Pt(100)/Ti/SiO₂/Si(100) substrate. PZT buffer layer was derived by MOCVD method (label: PZT₁) and sputtering method (label: PZT₂) respectively. XRD analysis indicated that high (110) orientation of BFO in the BFO/PZT₁ structure was achieved. SEM analysis indicated a better microstructure in the BFO/PZT₁ structure compared with BFO/PZT₂. The remnant polarization of the BFO/PZT₁ was 82.5 μ C/cm² at an applied voltage of 8 V, compared with that of 25.2 μC/cm² in the BFO/PZT₂ structure. The BFO/PZT₁ multilayer exhibited little polarization fatigue (<1.5%) upon 1×10¹⁰ switching cycles, at an applied voltage of 4 V. The leakage current density was about 2×10₋₇ A/cm² at an applied voltage 4 V, in the BFO/PZT₁ capacitor. All the results indicated that PZT can act as an inducing layer to the BFO and the MOCVD derived PZT has more inducing effect to the BFO thin film at room temperature. Supported by the National Natural Science Foundation of China (Grant No. 60601003), Ying Tong Education Foundation (Grant No. 101063), and International Cooperation Project from Ministry of Science and Technology of China (Grant No. 2008DFA12000)     

W-Sc2O3靶材的SPS制备和性能研究

采用溶胶凝胶法加二段还原, 制备出晶粒直径500~1100 nm的亚微米W-Sc₂O₃粉末, 利用放电等离子烧结(spark plasma sintering, SPS)制备了W-Sc₂O₃靶材.对不同粉末处理条件下的W-Sc₂O₃烧结体的密度、硬度、表面形貌进行测试研究.结果表明, 亚微米尺度的W粉在1 300℃即可烧结, 远低于常规W粉烧结温度, 获得的烧结体相对密度达96.4%、硬度为86.4HRC且Sc元素分布均匀.