石墨烯薄膜修饰TiO2纳米管光电极制备及性能

为提高TiO₂光催化剂的可见光催化活性,采用阳极氧化法制备了高度有序的TiO₂纳米管,利用阳极电化学沉积构筑了石墨烯薄膜修饰的TiO₂纳米管光电极,并利用扫描电子显微镜、X-射线光电子能谱及紫外-可见漫反射光谱对其表观形貌、组成结构及光吸收性能进行表征．结果表明:石墨烯有效地修饰在TiO₂纳米管表面,且以透明薄膜形式存在．此外,石墨烯薄膜修饰显著拓展了TiO₂纳米管的可见光响应范围．以甲基蓝为探针分子,考察了阳极沉积电压及沉积时间对所制备石墨烯薄膜／TiO₂纳米管光电极光催化性能的影响．结果表明:阳极沉积电压为+0.8 V、沉积时间为10 min时,制备的石墨烯薄膜／TiO₂纳米管光电极对甲基蓝的光催化降解效果最佳．模拟太阳光下光照120 min对甲基蓝的降解率为65.9％,是纯TiO₂纳米管光电极的1.35 倍．     

沸石负载Mn,N共掺杂TiO2及光催化性能

为提高传统TiO₂光催化剂的可见光催化活性,本文采用溶胶-凝胶法合成了Mn,N共掺杂TiO₂光催化剂,改善了传统TiO₂光生载流子易复合的问题;进一步采用沸石作为载体对改性后的TiO₂样品进行负载,解决了传统光催化剂存在的难分离回收问题,以达到光催化剂可重复使用的目的.借助X-射线衍射仪、扫描电子显微镜、紫外分光光度计、傅立叶变换红外光谱仪等测试手段对Mn,N共掺杂TiO₂光催化剂的结构、元素组成、微观形貌和光催化降解性能进行系统分析与研究.研究结果表明,沸石负载Mn,N共掺杂TiO₂的样品较未改性的TiO₂样品具有更高的光催化降解活性,在可见光照射下,在最优掺杂条件下获得的TiO₂光催化剂在60 min内对孔雀石绿的降解率可达到97%,这主要归因于锰离子掺杂能够对TiO₂光生载流子的复合产生抑制作用,促进光生电荷分离,与此同时氮元素掺杂可有效拓宽TiO₂半导体光催化剂光响应范围.此外,经过5次循环使用后,对孔雀石绿的降解率没有较大程度的减弱,依然能够维持在88%以上,表明沸石负载Mn,N共掺杂TiO₂的样品具有较好的光催化循环稳定性.     

TiO2/石墨烯复合材料的水热法合成与光催化性能

为了提高TiO₂的光催化性能,采用水热法一步制备了TiO₂/石墨烯(TiO₂/RGO)复合物．采用XRD、FT-IR、RS、UV-Vis DRS、TEM等测试方法对其进行了表征,并研究了不同质量比的复合物在可见光下对甲基橙(MO)的光催化降解．结果表明:在TiO₂/RGO复合物中,TiO₂以10 nm左右的颗粒均匀地分散在石墨烯层上;与在同等条件下制备的TiO₂相比,TiO₂/RGO复合物在可见光区吸收明显增强,吸收边缘红移了20 nm;质量比为1∶0.005的TiO₂/RGO复合物,2 h内的降解率达到74.79％．可见将石墨烯与TiO₂复合,能够有效地提高TiO₂的可见光催化性能．     

Pd纳米晶修饰TiO2纳米管阵列光电极的制备及性能

为提高TiO₂的可见光催化性能,采用阳极氧化法在Ti箔上原位生成TiO₂纳米管阵列,再利用阴极电沉积法制备了贵金属Pd纳米晶修饰的TiO₂纳米管阵列光电极,并利用扫描电子显微镜（SEM）、X-射线光电子能谱（XPS）及紫外-可见漫反射光谱（UV-vis DRS）对其表观形貌、表面形态及光吸收性能进行表征．结果表明:Pd纳米晶有效地修饰在TiO₂纳米管阵列的表面,且以Pd⁰形式存在．此外,Pd纳米晶修饰明显拓展了TiO₂纳米管阵列的可见光响应范围．以甲基蓝为模型污染物,重点考察阴极沉积电压及沉积时间对其光催化性能的影响．结果表明:阴极沉积电压为-0.8 V、沉积时间为10 min对甲基蓝的光催化降解效果最佳,且符合拟一级反应动力学模型．模拟太阳光下光照120 min对甲基蓝的降解率可达71.4％,是纯TiO₂纳米管阵列光电极的1.5 倍．     

模板法合成三维菊花状TiO2纳米花及其性能

为了解决一维、二维纳米材料在降解有机污染物时,易发生团聚、催化活性低、难以回收利用等问题,以TiO₂(P25)和NaOH为原料,ZnO为模板,采用水热法合成了三维菊花状TiO₂纳米花．运用扫描电子显微镜、X射线衍射仪、氮气吸附脱附、紫外-可见漫反射、傅立叶红外等手段对合成的样品进行测试分析. 结果表明:其花瓣是由TiO₂纳米颗粒通过自组装定向排列而成的链状结构,构成纳米花的粒子晶粒尺寸约15 nm,花状结构尺寸约为5 μm,结晶性良好,为锐钛矿相;比表面积为102.3 m²／g,平均孔径为17.41 nm;以亚甲基蓝为目标污染物,在紫外光照射下对其进行光催化性能实验,80 min亚甲基蓝的降解率为98％,催化活性高于P25,显示出较强的光催化活性．     

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。     

水环境中不同浓度TiO2纳米颗粒混凝工艺去除效果

为了探究水环境中不同质量浓度TiO₂ 纳米颗粒(NPs)混凝工艺去除影响因素及与浊度去除规律的区别,研究了在超声预处理后投加表面活性剂(LAS)对TiO₂ NPs分散稳定性的影响,通过烧杯实验分别考察了混凝剂(聚合氯化铝,PAC)投加量及pH对不同质量浓度TiO₂ NPs和浊度去除的影响,及pH对TiO₂ NPs表面Zeta电位的影响机制．结果表明,在250 W超声处理10 min后加入20 mg／L的LAS获得的纳米悬浮液稳定性最好;不同混凝剂投加量下,TiO₂ NPs和浊度的去除规律呈相近趋势,TiO₂ NPs初始质量浓度为0.5,1和2 mg／L时,PAC最优投加量为3 mg／L,对应TiO₂ NPs和浊度最大去除率分别为46.2％、60.2％、68.8％和23.2％、43.6％、47.6％．TiO₂ NPs初始质量浓度为5 mg／L时,PAC最优投量为4 mg／L,TiO₂ NPs和浊度最大去除率分别为77.64％和54.08％．pH对TiO₂ NPs表面Zeta电位有明显影响,进而影响TiO₂ NPs的去除效果．     

TiO2对高C3S熟料烧成的影响

通过外掺TiO₂来改善高C₃S熟料的烧成.配制7个生料样品,其潜在矿物组成均为w(C₃S)=75%、w(C₃A)=7%、w(C4AF)=18%,TiO₂掺量分别为0、05%、10%、15%、20%、25%、30%,在设定的高温下煅烧成熟料,通过化学分析、XRD、SEM/EDS等方法,研究了TiO₂对熟料易烧性、矿相形成、C₃S晶体形貌和熟料强度等的影响.结果表明,掺入少量TiO₂明显提高了熟料的易烧性;当TiO₂掺量小于2%时,f-CaO随TiO₂掺量的增加而显著降低;当TiO2掺量超过2%后,f-CaO随TiO₂掺量的变化不大;当TiO₂掺量达到3%时,在1 350和1 400 ℃温度煅烧的熟料中均发现了CaO·TiO₂新相;掺2%TiO2在1 400℃煅烧条件下的熟料,TiO₂在C₃S中的固溶量约1.7%;掺入适量的TiO₂,熟料中C₃S结晶比较完整、均匀,熟料强度较高.适当掺入TiO₂对改善高C₃S熟料的烧成和提高其强度都是有利的.     

高效CoFe2O 4的制备及其碱性析氧性能

析氧反应(oxygen evolution reaction, OER) 电催化剂存在成本高、效率低等问题。OER 是一个需要高过电 位的四电子-质子耦合反应, 为了降低电解水阳极的OER 过电位和提高钴铁氧化物(CoFe₂O₄) 的电流密度和稳定 性, 采用简单的水浴和煅烧的方法制备不同煅烧温度的非贵金属催化剂CoFe₂O₄。采用XRD、SEM、TGA 等方法 对CoFe₂O₄ 材料进行表征, 电化学研究结果表明, 在1 mol/L KOH 溶液中, 经过300 ℃ 煅烧的CoFe₂O₄ OER 性能最好, 1.58 V 时就可以产生10 mA/cm² 的电流密度, 塔菲尔(Tafel) 斜率为96 mV/dec, 经过1 000 次循环伏安扫描和计 时电流进行稳定性测试后, 其析氧性能依然保持较高的稳定性。     

KMnO4/NaOH溶液吸收SO2/NO的动力学研究

在典型湿法烟气脱硫系统运行条件下,研究了平面传质搅拌反应器中KMnO₄/NaOH溶液同时吸收SO₂和NO的动力学,确定了反应级数、反应速率常数以及活化能.实验结果表明,NO的吸收速率随着入口NO分压和KMnO₄浓度的增加而提高.在吸收剂溶液中加入NaOH可以提高NO的吸收速率,烟气中O₂的体积分数对于NO和SO₂的吸收速率几乎没有影响.当同时吸收烟气中的SO₂和NO时,SO₂会降低NO的吸收速率,而NO对SO₂的吸收速率几乎没有影响.在KMnO4/NaOH溶液中NO的吸收速率对NO相间浓度和KMnO4浓度均为一级反应,平均反应速率常数为5.79×103 m³/(mol•s),活化能为26.85 kJ/mol.     

SnO2及SnO2／Fe2O3复合微米材料的合成及表征

本文首先以SnCl2·2H2O为主要原料,无水乙醇为溶剂,利用溶剂热法于180℃反应24h得到了SnO2微球;再以所制备的SnO2微球为前驱体,FeCl3·6H2O为主要原料,通过水热法得到SnO2／Fe2O3复合材料．利用X射线粉末衍射仪（XRD）和扫描电子显微镜（SEM）对所得产物进行了表征．结果表明：所得的SnO2为四方锡石型,形貌为微球,平均直径约为2．0μm;复合后得到的SnO2／Fe2O3微球平均直径约为2．5μm．其中,Fe2O3为六方赤铁矿型,在复合物的表面以小颗粒的形式存在,尺寸约为200nm．另外,也对SnO3与SnO2／Fe2O3微球的形成过程进行了讨论．     

Temperature dependence on reaction of CaCO3 and SO2 in O2/CO2 coal combustion

The temperature dependence on the reaction of desulfurization reagent CaCO₃ and SO₂ in O₂/CO₂ coal combustion was investigated by thermogravimetric analysis, X-ray diffraction measurement and pore structure analysis. The results show that the conversion of the reaction of CaCO₃ and SO₂ in air is higher at 500–1 100 °C and lower at 1 200 °C compared with that in O₂/CO₂ atmosphere. The conversion can be increased by increasing the concentration of SO₂, which causes the inhibition of CaSO₄ decomposition and shifting of the reaction equilibrium toward the products. XRD analysis of the product shows that the reaction mechanism of CaCO₃ and SO₂ differs with temperature in O₂/CO₂ atmosphere, i.e. CaCO₃ directly reacts with SO₂ at 500 °C and CaO from CaCO₃ decomposition reacts with SO₂ at 1 000 °C. The pore analysis of the products indicates that the maximum specific surface area of the products accounts for the highest conversion at 1 100 °C in O₂/CO₂ atmosphere. The results reveal that the effect of the atmosphere on the conversion is temperature dependence.     

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.     

Bi2O3和Fe2O3掺杂对BaTiO3陶瓷显微结构的影响

利用扫描电子显微镜(SEM)、透射电子显微镜(TEM)和X射线能量色散谱(EDAX)等结构分析技术,研究了施主(Bi     

Dielectric properties of Pb (Zn1/3 Nb2/3) O3?PbZrO3?PbTiO3 solid solution near morphotropic phase boundary

The dielectric properties of Pb(Zn_1/3Nb_2/3) O₃-PbZrO₃−PbTiO₃ (PZN-PZ-PT) system near the rhombohedral/tetragonal morphotropic phase boundary (MPB) are carefully studied in this paper. It is found that, for all samples, the curves around the temperatures of dielectric permittivity peak show the characteristics of diffuse phase transition. The change in PbZrO₃/PbTiO₃ ratio has much influence on the dielectric properties of the samples. The extent of diffuse phase transition increases with the increasing Zr/Ti ratio. The samples in rhombohedral region have typical diffuse phase transition in the temperature range measured. However, for the samples with tetragonal symmetry, a spontaneous normal ferroelectric-relaxor phase transition exists at temperature lower than that of permittivity peak. This normal ferroelectric-relaxor phase transition is confirmed by the experiment of thermally driven current. The analysis of TEM reveals that the samples in tetragonal region show a 90% macrodomain structure, while the samples in rhombohedral region have the configuration of microdomain structure.     

三氧化二铝是导致建筑物火灾的严重隐患

建筑物供电线路中的铜线与铝线连接处常常生成一种灰白物质－－三氧化二铝,极易引发建筑物火灾。着重介绍和分析这种灰白物质的成分、生成原因、危害以及防止其生成的主要措施。     

Characteristics of LiCoO2, LiMn2O4 and LiNi0.45Co0.1Mn0.45O2 as cathodes of lithium ion batteries

LiNi_0.45Co_0.10Mn_0.45O₂ was synthesized from Li₂CO₃ and a triple oxide of nickel, cobalt and manganese at 950 °C in air. The structures and characteristics of LiNi_0.45Co_0.10Mn_0.45O₂, LiCoO₂ and LiMn₂O₄ were investigated by XRD, SEM and electrochemical measurements. The results show that LiNi_0.45Co_0.10Mn_0.45O₂ has a layered structure with hexagonal lattice. The commercial LiCoO₂ has sphere-like appearance and smooth surfaces, while the LiMn₂O₄ and LiNi_0.45Co_0.10Mn_0.45O₂ consist of cornered and uneven particles. LiNi_0.45Co_0.10Mn_0.45O₂ has a large discharge capacity of 140.9 mA · h/g in practical lithium ion battery, which is 33.4% and 2.8% above that of LiMn₂O₄ and LiCoO₂, respectively. LiCoO₂ and LiMn₂O₄ have higher discharge voltage and better rate-capability than LiNi_0.45Co_0.10Mn_0.45O₂. All the three cathodes have excellent cycling performance with capacity retention of above 89.3% at the 250th cycle. Batteries with LiMn₂O₄ or LiNi_0.45Co_0.10Mn_0.45O₂ cathodes show better safety performance under abusive conditions than those with LiCoO₂ cathodes. Foundation item: Project(50302016) supported by the National Natural Science Foundation of China; Project(2005037698) supported by the Postdoctoral Science Foundation of China     

Modification of nano-TiO2 by Al2O3 in-situ coating

A novel technology of in-situ coating Al₂O₃ on the surface of H₄TiO₄ was developed to prevent the aggregation of nano-TiO₂ powders and improve the dispersibility and thermal stability in the way of forming a uniform coating layer. The heterogeneous nucleation was conducted to prepare the precursor of nano-TiO₂ and then Al₂O₃ was coated on the surface of precursor. The effects of Al₂O₃ in-situ coating on the properties of nano-TiO₂ were investigated. The results show that H₄TiO₄ can be dispersed well under alkaline condition (pH 8.5) and the heterogeneous nucleation can be controlled easily. The optimized uniform coating layer is obtained by adding 5% (mass fraction) and 10% of Al₂O₃ and the aggregation of nano-TiO₂ powders is effectively inhibited and the dispersibility is obviously improved. The crystal sizes of TiO₂ powders are 12.3, 11.4 and 8.7 nm after coating 0,5% and 10% of Al₂O₃ respectively. Al₂O₃ on the surface of particulates in amorphous phase could increase the thermal stability of nano-particles after calcined at 550 °C. Foundation item: Project(04GK2007) supported by Hunan Industrial Key Project of Science and Technology     

Electrolysis expansion performance of semigraphitic cathode in [K3AlF6/Na3AlF6]-AlF3-Al2O3 bath system

The electrolysis expansion of semigraphitic cathode in [K₃AlF₆/Na₃AlF₆]-AlF₃-Al₂O₃ bath system was tested by self-made modified Rapoport apparatus. A mathematical model was introduced to discuss the effects of α _CR (cryolite ratio) and β _KR (elpasolite content divided by the total amount of elpasolite and sodium cryolite) on performance of cathode electrolysis expansion. The results show that K and Na (potassium and sodium) penetrate into the cathode together and have an obvious influence on the performance of cathode electrolysis expansion. The electrolysis expansion and K/Na penetration rate increase with the increase of α _CR. When α _CR=1.9 and β _KR=0.5, the electrolysis expansion is the highest, which is 3.95%; and when α _CR=1.4 and β _KR=0.1, the electrolysis expansion is the lowest, which is 1.28%. But the effect of β _KR is correlative with α _CR. When α _CR=1.6 and 1.9, with the increase of β _KR, the electrolysis expansion and K/Na penetration rate increase. However, when α _CR=1.4, the electrolysis expansion and K/Na penetration rate firstly increase and then decrease with the increase of β _KR. Foundation item: Project (2005CB623703) supported by the Major State Basic Research and Development Program of China; Project (2008AA030502) supported by the National High-Tech Research and Development Program of China     

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)