染料敏化太阳能电池用TiO2薄膜电极的改性制备及光电化学性能

以钛酸四异丙酯为钛源, 用水热法合成制备了具有典型锐钛矿晶型的TiO2纳米材料. 采用金属镍掺杂和表面包覆一层氧化钕, 对TiO2薄膜电极进行改性研究. 实验结果表明, 所制备纳米TiO2颗粒较均匀, 粒径约为17~18 nm. 经镍掺杂后, 颗粒团聚粒径明显增大, 但是仍保持均匀状态和多孔结构. 与改性前的TiO2薄膜电极相比, 金属掺杂和表面包覆有助于光生电子和空穴有效地分离, 电池的短路光电流提高了16%, 光电转换效率提高了17%.     

TiO2薄膜优化对染料敏化太阳电池性能的影响

纳米TiO2多孔薄膜微结构对染料敏化太阳电池(DSC)光伏性能有很大的影响。本文采用不同实验和测试方法研究和分析了溶胶-凝胶法制备纳米TiO2颗粒时的热处理温度、TiO2多孔薄膜厚度、纳米TiO2大颗粒光散射、TiCl4溶液处理和电沉积致密TiO2层对纳米多孔薄膜电极和染料敏化太阳电池光伏性能的影响,得到了最佳的优化条件,为纳米TiO2薄膜材料的批量化制作打下了良好基础。     

一步水热法制备TiO2复合结构及光伏性能

采用一步水热法制备TiO2纳米棒阵列,研究了无水乙醇作为前驱物替换去离子水对纳米棒阵列的形貌的影响。实验发现,当无水乙醇的含量达到100%的时候,在生长的TiO2纳米棒阵列的上面获得一层以TiO2纳米棒为基本单元的微米球,从而制备出TiO2复合纳米阵列薄膜。通过XRD和TEM发现,样品为单晶四方金红石结构TiO2构成的阵列薄膜,将样品组装成染料敏化太阳能电池后,电池的开路电压和短路电流分别为Voc=0.63 V,Jsc=10.9 mA·cm-2,填充因子FF=56.3%,转换效率达到η=4.1%。     

含有TiO2刺球散射中心光阳极的设计及其在染料敏化太阳能电池的应用

采用水热法制备了一种刺球状TiO_2(NT),将其作为光散射中心,与纳米晶TiO_2混合,制备成一种底层为P25薄膜(作为染料吸收层),上层为添加NT散射层的混合结构的薄膜光阳极。探讨了NT添加量对薄膜性能的影响,实验结果表明,当NT与P25粉体的质量比为35%时电池光电性能最优,电池短路光电流密度为14.30 m A·cm~(-2),其光电转换效率达到7.38%。质量比继续增大,当达到50%时电池性能有所下降,光电转换效率降为5.99%,同时染料吸附量也由73.2μmol·cm~(-2)降到70.1μmol·cm~(-2)。这表明过量的大颗粒TiO_2刺球散射中心会减少光阳极的比表面积从而降低染料的有效吸附量,并且还会引起不必要的反向散射,只有适量的散射中心才能得到最佳性能的太阳能电池器件。     

含有TiO2刺球散射中心光阳极的设计及其在染料敏化太阳能电池的应用

采用水热法制备了一种刺球状TiO₂（NT）,将其作为光散射中心,与纳米晶TiO₂混合,制备成一种底层为P25薄膜（作为染料吸收层）,上层为添加NT散射层的混合结构的薄膜光阳极。探讨了NT添加量对薄膜性能的影响,实验结果表明,当NT与P25粉体的质量比为35%时电池光电性能最优,电池短路光电流密度为14.30 mA·cm^-2,其光电转换效率达到7.38%。质量比继续增大,当达到50%时电池性能有所下降,光电转换效率降为5.99%,同时染料吸附量也由73.2 μmol·cm^-2降到70.1 μmol·cm^-2。这表明过量的大颗粒TiO₂刺球散射中心会减少光阳极的比表面积从而降低染料的有效吸附量,并且还会引起不必要的反向散射,只有适量的散射中心才能得到最佳性能的太阳能电池器件。     

双层结构CeO2光阳极在染料敏化太阳能电池中的应用

利用水热法合成核壳结构Au@SiO₂@CeO₂纳米微球,制备了一系列双层结构复合光阳极并应用于染料敏化太阳能电池(DSSC)。研究表明：当CeO₂纳米微球和核壳结构Au@SiO₂@CeO₂纳米微球应用于DSSC光阳极散射层时,电池的光电转化效率有了显著提高。相对于纯 TiO₂ (P25)光阳极,P25/CeO₂纳米球光阳极电池的 DSSC 光电性能提高了 15.3%,P25/Au@SiO₂@CeO₂纳米球光阳极电池的光电性能提高了27.9%。DSSC光电性能的提高主要归因于2个方面：一方面,Au纳米粒子的表面等离子体共振效应有效提高了光阳极薄膜的光散射效应。另一方面,CeO₂具有较高的染料负载能力,核壳球形结构具有较高的比表面积,增强了光的散射效应,提高了电子传输能力。     

双层结构CeO2光阳极在染料敏化太阳能电池中的应用

利用水热法合成核壳结构Au@SiO₂@CeO₂纳米微球,制备了一系列双层结构复合光阳极并应用于染料敏化太阳能电池(DSSC)。研究表明：当CeO₂纳米微球和核壳结构Au@SiO₂@CeO₂纳米微球应用于DSSC光阳极散射层时,电池的光电转化效率有了显著提高。相对于纯TiO₂(P25)光阳极,P25/CeO₂纳米球光阳极电池的DSSC光电性能提高了15.3%,P25/Au@SiO₂@CeO₂纳米球光阳极电池的光电性能提高了27.9%。DSSC光电性能的提高主要归因于2个方面：一方面,Au纳米粒子的表面等离子体共振效应有效提高了光阳极薄膜的光散射效应。另一方面,CeO₂具有较高的染料负载能力,核壳球形结构具有较高的比表面积,增强了光的散射效应,提高了电子传输能力。     

纳米TiO2/Si薄膜的制备与光催化性能的研究

1972年, Fujishima等发现受辐射的TiO₂上可以持续发生水的氧化还原反应产生氢, 从此, 半导体光催化受到了重视并得到进一步广泛的研究^[1]。     

改进型溶胶-凝胶法制备粒径可调高染料吸附量TiO2微球及其在染敏电池光散射层中的应用

利用改进型的溶胶-凝胶法,制得了由锐钛矿相纳米颗粒组成的TiO2多孔微纳小球。通过调节前驱物浓度,合成出粒径可控的尺寸分别为100,175,225,475 nm的TiO2微纳小球,并通过电泳沉积法将合成出的小球作为光散射层引入到染料敏化太阳电池(DSSC)中。由于这种微纳小球在具备良好的光散射性能的同时也具备较高的染料吸附量,因此相较于基于纳米颗粒的单层结构的DSSC拥有更高的光电转换效率。通过比较分析,粒径尺寸为475 nm的微球作为光散射层的DSSC光电转换效率可以达到6.3%,较之于基于纳米颗粒的DSSC提高了30%。     

两步电泳沉积制备TiO2光阳极用于高效染料敏化太阳能电池

采用不同沉积电压制备TiO₂光阳极,研究电压对薄膜沉积速率、厚度和形貌的影响。通过台阶仪、光学照片、扫描电子显微镜（SEM）、电化学交流阻抗谱、开路电压衰减曲线对光阳极和电池进行系统表征,并测试了染料敏化太阳能电池器件的电流密度-电压（J-V）曲线,计算其光电转换效率。结果表明,提高沉积电压时,光阳极薄膜的沉积速率加快,膜厚也增加,但是电压过高时,薄膜会有裂缝和覆盖不全的问题,这会对电池的效率造成负面影响。综合考虑低沉积电压条件下薄膜均匀无裂缝和高沉积电压条件下沉积速率快的优点,采用先30 V电压、后60 V电压的电泳沉积方式来制备光阳极,结果呈现协同效果,既降低了制备时间又得到高质量的薄膜,在无其他修饰的情况下,电池的光电转换效率可以达到7.29%。     

Preparation and properties of FeAs2 and FeSb2

Single crystals of FeAs₂ and FeSb₂ were prepared by chemical vapor transport using chlorine as the transporting agent. Electrical and magnetic measurements have been made on well-characterized samples. FeAs₂ was found to be a diamagnetic semiconductor with a band gap of 0.22 eV. FeSb₂ has an extremely narrow band gap and shows unusual electrical and magnetic properties. Aproposed band model is used to explain the experimental results.     

Effects of nano-TiO2 dispersion on the thermoelectric properties offilled-skutterudite Ba0.22Co4Sb12

Homogeneously dispersed nano-TiO₂ was introduced into the matrix of n-type barium-filled cobalt antimony (Ba_0.22Co₄Sb₁₂) via sol–gel method successfully. The Seebeck coefficients are improved and the lattice thermal conductivities are depressed with a proper addition of nano-TiO₂ not more than 0.8 vol.%, while the electrical conductivities nearly remain unchanged. The effects of n-type semiconductive nanoscale inclusions on the electrical and thermal transport characteristics are discussed. Microstructure analyses indicate that the fine nanoinclusions locate on the grain boundaries as well as inside grains, which serve as extra phonon scattering mode and new type energy filtering. As a result, the optimal ZT value was achieved for the sample of 0.4 vol.% TiO₂ composition.     

Investigation of the photocatalytic degradation of organochlorine pesticides on a nano-TiO2 coated film

The photocatalytic degradation of organochlorine pesticides including -, β-, γ-, δ-hexachlorobenzene (BHC), dicofol and cypermethrin were carried out on a nano-TiO₂ coated films under UV irradiation in the air. The photocatalytic conditions, including the amount of TiO₂, irradiation time and the intensity of light were optimized. The pesticides were most effectively degraded under the condition of 2.24 mg/cm² on TiO₂ film and a 400 W UV irradiation of high-pressure mercury lamp with a wavelength of 365 nm. A typical organochlorine pesticide, 20 μg -BHC, was dipped onto the TiO₂ film surface and degraded completely within 20 min. In addition, the photocatalytic degradation pathways on the nano-TiO₂ coated film were discussed.     

WS2/CuGa2O4复合材料的制备及其气敏性

采用共沉淀法制备了CuGa₂O₄纳米材料,并利用水热法制备了一系列WS₂/CuGa₂O₄复合材料。结合X射线衍射(XRD)、扫描电子显微镜(SEM)、X射线光电子能谱(XPS)等对制备的材料进行了物相组成、表面形貌以及元素价态的分析。研究了WS₂的复合量对 CuGa₂O₄材料检测乙醇气体敏感性能的影响。实验结果表明,当 WS₂与 CuGa₂O₄质量比为 1%时,该复合材料制备的传感器在室温下对 100 μL·L^-1乙醇气体表现出 345.3 的灵敏度,响应时间和恢复时间分别为 184 和 69 s,且最低检测限为 0.1μL·L^-1。     

ZnFe2O4/Ag/TiO2复合材料的制备及其光催化性能

以硝酸银、钛酸四丁酯、无水氯化锌、六水氯化铁为原料,采用溶胶-凝胶法与溶剂热相结合的方法制备了ZnFe₂O₄/Ag/TiO₂复合材料,通过扫描电子显微镜、能谱分析仪、X射线粉末衍射仪、X射线光电子能谱仪、振动样品磁强计、紫外可见分光光度计对样品进行表征及测试。结果表明： ZnFe₂O₄/Ag/TiO₂-10具有最佳的光催化效果,在紫外和可见光下对染料的降解率都能达到90%以上,具有优异的紫外可见光光催化活性。ZnFe₂O₄/Ag/TiO₂具有独特的磁性,能在外部磁场作用下进行回收利用,这使其在实际应用中成为可能。通过磁分离技术重复回收利用5次后仍然保持优良的光催化性能,说明ZnFe₂O₄/Ag/TiO₂-10具有优异的磁性及较高的光催化循环稳定性。     

Preparation and electrorheological properties of triethanolamine-modified TiO2

The high molecular dielectric dipole moment of doping material is promising to improve the electrorholegical (ER) effect. It is found that triethanolamine (the molecular dipole moment of triethanolamine is 3.48)-modified TiO₂ has good ER properties. Under 5 kV/mm external electric field, the yield stress is 32.6 kPa, which is about 50 times higher than that of pure TiO₂ and the leaking electric current density is lower than 16 μA/cm². The sedimentation rate is about 98% in 20 days.     

Preparation and magnetic properties of Fe-Nb co-doped SnO2

Fe³⁺-Nb⁵⁺ co-doped SnO₂ was prepared at 1200 °C by a simple chemical co-precipitation method. The Sn_1−2xFe_xNb_xO₂ solid solutions kept cassiterite structure in the range of 0<x?0.33, and their cell parameters decrease with increasing x. While x=0.40, a second phase with orthorhombic FeNbO₄ structure co-exists with the cassiterite phase, and the second phase becomes dominant while x?0.45. The magnetic measurements indicated that low doping ratio sample (x=0.03) exhibits paramagnetic behavior. A paramagnetic-to-antiferromagnetic phase transition was observed for the samples with higher doping ratio (x?0.15).     

Preparation and some properties of ScB2 single crystals

ScB₂ single crystals were grown by inductive floating zone melting. The ScB₂ structure was refined on single crystal and powder data, the latter obtained from parts of single crystals which were prepared by controlled crushing. The ScB₂ structure corresponds to the AlB₂ structure type, sp. gr. P6/mmm, No. 191 (R₁=0.0191, wR₂=0.0474), lattice parameters are equal to a=0.314820(3) nm, c=0.351483(5) nm, c/a=1.117, X-ray density is 3.670 g/cm³. The measured hydrostatic density is 3.666 g/cm³ which correspond to the Sc_0.99B₂ composition. The ScB₂ Young modulus value is equal to 480 GPa and the Debye characteristic temperature is 1020 K.     

MnO2纳米线支撑中空十二面体CoNi2S4的制备及其电化学性能

采用简单的室温搅拌法和一步硫化法制备了 MnO₂纳米线支撑中空十二面体 CoNi₂S₄ (MnO₂/CoNi₂S₄)电极材料。超长MnO₂纳米线为电子转移提供了直接路径,而且其较大的长径比有利于形成自支撑的三维导电网络结构;中空多孔的CoNi₂S₄提供了更丰富的活性位点,同时缓解了充放电过程中的体积变化。得益于以上优势,MnO₂/CoNi₂S₄在1 A·g^-1时具有1 531.1 F·g^-1的比电容,在 10 A·g^-1时具有 86.9% 的电容保持率。利用 MnO₂/CoNi₂S₄作为正极、活性炭(AC)为负极组装的 MnO₂/CoNi₂S₄||AC器件实现了高能量密度(800 W·kg^-1时40 Wh·kg^-1)和优异的循环稳定性(5 000次循环后保持64.8%)。     

Quenching of TiO2 photo catalysis by silver nanoparticles

The plasmon resonance of metal nanostructures affects neighboring semiconductors, quenching or enhancing optical transitions depending on various parameters. These plasmonic properties are currently investigated with respect to topics such as photovoltaics and optical detection and could also have important consequences for photocatalysis. Here the effect of silver nanoparticles of a size up to 30 nm and at maximum 0.50 monolayers on the photocatalytic oxidation of ethylene on TiO₂ is studied. Since the plasmon resonance energy of silver nanoparticles is comparable with the TiO₂ band gap, dipole-dipole interaction converts excitons into heat at the silver nanoparticle. This indicates that plasmonic interaction with TiO₂ semiconductor catalysts can reduce the photo catalytic activity considerably.