染料敏化太阳能电池中TiO2光阳极形貌研究进展

纳米TiO2具有合适的禁带宽度(3.2 eV)、良好的光电化学稳定性、价格低廉、易牢固吸附染料等优点,目前仍是应用于染料敏化太阳能电池(DSSC)主要的半导体材料。TiO2光阳极是DSSC的重要组成部分之一,其晶体的形貌与DSSC的光电性能密切相关。本文综述了应用于DSSC中不同形貌TiO2光阳极,重点探讨了常规TiO2光阳极形貌,如纳米粒子、纳米棒、纳米线、纳米管;对新型TiO2光阳极及复合光阳极的形貌也作了介绍。讨论了不同形貌TiO2光阳极的制备方法及其结构对DSSC光电性能的影响,提出TiO2光阳极今后的研究方向是将不同形貌光阳极进行复合或混合掺杂来提高电子传输速率、优化TiO2薄膜厚度、控制TiO2薄膜中晶体结构抑制电荷再结合、提高电荷传输效率。     

二氧化钛包覆氧化锌纳米阵列光阳极的制备与性能

采用直流反应磁控溅射工艺,在ZnO纳米阵列的表面实现TiO2包覆,作为染料敏化太阳能电池光阳极,研究TiO2--ZnO核壳结构的形成机理和制备工艺对其光电性能的影响。利用X射线衍射仪、扫描电子显微镜、能谱分析仪表征光阳极材料的成分与结构。测试电池组件的伏安特性曲线、电压-时间曲线和电化学阻抗谱,分析TiO2包覆对电子传输性能和光电转换效率的影响机理。结果表明:磁控溅射制备的TiO2颗粒完整地包覆ZnO纳米阵列,使得纳米棒表面形貌由六棱柱向圆柱状转变,间隙变窄,直径较ZnO纳米阵列有所增加,阵列有序度得到改善。随着延长染料吸附时间和TiO2包覆,光阳极界面电子传输阻抗显著增加,光生电子的寿命也得到提高。经过包覆的光阳极能够作为阻挡层钝化表面缺陷,抑制复合的发生,从而提高开路电压和填充因子。经过包覆的光阳极其光电转换效率相对于纯ZnO纳米阵列提高了132%。     

染料敏化太阳电池TiO2光阳极研究进展

纳米TiO2是目前性能最为优良的染料敏化太阳电池(DSSC)光阳极材料。文章系统综述了优化纳米TiO2光阳极的染料吸附、电子传输、再生染料等性能的技术和方法,主要包括纳米TiO2光阳极薄膜微结构的调控、TiO2光阳极的离子/元素掺杂、TiO2光阳极的表面包覆、TiO2光阳极的表面处理等方面的国内外研究进展,并分析了目前TiO2光阳极存在的主要问题及未来的发展方向。     

柔性染料敏化太阳能电池材料制备工艺参数的优化

采用水热法制备TiO2纳米浆,与P25粒子和TiO2散射大粒子混合制成级配浆料。将所得的浆料涂敷在铟掺杂氧化锡-聚苯二甲酸乙二醇酯导电聚合物基板上,并在120～150℃进行热处理制成光阳极薄膜。利用溅射法制备Pt对电极,将其组装成柔性的染料敏化太阳能电池(dye-sensitized solar cell,DSC)。研究了对电极溅射时间、TiO2薄膜热处理温度、膜厚以及级配浆料中的酸添加量对电池光电性能的影响。结果表明:当对电极Pt溅射时间为30s,TiO2薄膜热处理温度为150℃,膜厚为10.5μm,浆料添加0.05mol/LHNO3时,柔性DSC的光电性能最好,光电转换效率可达4.05%。     

ZnO的水热合成及其在TiO2/ZnO染料敏化太阳能电池中的应用

通过在不同矿化剂粉末[六亚甲基四胺(hexamethylenetetramine,HMT)、尿素和氢氧化锂]存在下的水热反应制备得到具有不同形貌尺寸的ZnO粉体,通过X射线衍射、扫描电子显微镜、紫外可见漫反射光谱和表面光电压谱研究了不同矿化剂存在下所制备ZnO的尺寸、形貌和光电性能.结果表明:以HMT和LiOH作矿化剂可得到六方纤锌矿结构的ZnO粉体,且尺寸均一;尿素作矿化剂得到产物的结晶性较差;在LiOH存在下制备的ZnO具有明显的光电响应性能,这与带带跃迁及激子跃迁相关的.将所制备的ZnO用于染料敏化太阳能电池中,作为TiO2基染料敏化太阳能电池(dye-sensitized solar cells,DSSCs)光阳极的上层膜,起光散射作用,下层是纳米TiO2晶膜.作为对比,制备了单一ZnO基DSSCs.通过光电流-电压(I-V)曲线研究了2种DSSCs的光电转换效率,结果表明:TiO2/ZnO双层膜光阳极组装的DSSCs的光电性能优于ZnO基DSSCs,说明具有光散射层的DSSCs的光吸收增强归因于下层TiO2纳米晶膜的高比表面积和上层大尺寸ZnO光散射膜的组合效应.     

纳米TiO2光催化作用的影响因素及应用现状分析

研究了纳米TiO2光催化作用机理,并从晶体结构、晶粒尺寸、表面修饰及复合等因素对纳米TiO2光催化性能的影响作了分析。综述了目前TiO2光催化剂在环境保护、杀菌抗菌、光电转换等方面的应用现状。     

多壁碳纳米管对太阳能电池光阳极微裂纹的优化和性能的影响

在量子点敏化太阳能电池(QDSCs)中,多孔二氧化钛(TiO2)光阳极薄膜在烧结过程中会产生很多微小裂纹,影响电子传输,导致太阳能电池性能下降。利用多壁碳纳米管(MWCNTs)独特的管状结构和良好的导电性能来优化TiO2光阳极薄膜内部的微裂纹,探究了不同质量分数(0%、0.01%、0.05%、0.10%、0.50%)的MWCNTs对量子点敏化太阳能电池MWCNTs/TiO2复合光阳极性能的影响。对光阳极进行物相及微观形貌分析表明:加入适量的MWCNTs可以与TiO2纳米颗粒均匀混合,并且MWCNTs贯穿了光阳极薄膜表面的微裂纹。但是过多的MWCNTs会聚集成团,引入大量缺陷。采用连续离子层沉积法在以上的光阳极表面沉积硫化镉(Cd S)量子点和硫化锌(ZnS)量子点阻隔层,以硫化铜(Cu S)为对电极,多硫电解液为电解质组装电池试样,测量其伏安特性(J-V)曲线。结果表明:添加0.05%MWCNTs的TiO2光阳极电池的光电性能最优,其开路电压和短路电流密度分别可达0.65 V和11.51 mA/cm2,与未添加MWCNTs的光阳极电池相比,分别提高了16.1%和58.3%,其光电转化效率可达3.14%,提高了72.2%。     

染料敏化太阳能电池中TiO_2光阳极的包覆效果

采用原位包覆和浸泡包覆在染料敏化太阳能电池的TiO2光阳极表面包覆了一薄层Al2O3,MgO或ZnO,讨论了不同包覆方法和实验条件对染料敏化太阳能电池性能的影响。研究表明,无论是原位包覆还是浸泡包覆,都可以在TiO2光阳极表面均匀的形成一层厚度约为1～2nm的氧化物包覆层,抑制了TiO2光阳极中的光生电子与氧化态染料和氧化态电解质的复合,从而导致光电压都有明显增大。特别是浸泡包覆不仅可以提高光电压,而且在较大的TiO2浆料粒径、合适的前驱体溶液浓度下,还可以增加光电流,导致光电转换效率明显增加。     

花青素染料敏化太阳能电池的制备与性能

采用两种晶相TiO₂光阳极、蓝莓花青素染料、I-/I3-电解质溶液、复合碳层对电极制备了染料敏化太阳能电池。通过XRD、SEM分析了TiO₂纳米颗粒的微结构与形貌，以模拟太阳光和电化学工作站检测了电池的光电性能，结果发现，太阳能电池性能差异较大，金红石相光阳极电池的光电转换率为锐钛矿相光阳极电池的三倍多，结合TiO₂纳米颗粒形貌及电池的EIS分析了原因。     

CdS/PbS量子点共敏化三维结构TiO_2纳米管阵列光电极的制备及其光电化学性能表征

通过阳极氧化法在钛丝网基底上制备出三维结构的TiO2纳米管阵列。采用连续离子层吸附与反应法制备了CdS、PbS、CdS/PbS量子点(QDs)敏化TiO2纳米管阵列光电极。利用X射线衍射仪、扫描电子显微镜、能谱定量分析、高分辨透射电镜、紫外–可见漫反射光谱对其形貌和结构进行了表征。结果表明:CdS、PbS量子点成功沉积在TiO2纳米管阵列上,QDs/TiO2纳米管阵列具有比纯TiO2纳米管阵列更好的可见光吸收性能。使用电化学工作站测试光电极材料的光电化学性能,结果表明:QDs/TiO2纳米管阵列具有良好的可见光响应性和稳定性;在100mW/cm2氙灯光照下,CdS/PbS/TiO2光电极具有最高的光电流密度,为5.86mA/cm2,分别是单一量子点敏化CdS/TiO2、PbS/TiO2光电极的3.35、1.21倍。对比在钛片基底上的二维结构TiO2纳米管阵列,三维结构纳米管阵列的光电流随入射光角度增大而衰减的缺点得到极大改善,这对其在太阳能电池中的实际应用有重要意义。     

Insect antifeedant properties of anthranoids from the genusVismia

Vismiones and ferruginins, representatives of a new class of lypophilic anthranoids from the genusVismia were found to inhibit feeding in larvae of species ofSpodoptera, Heliothis, and inLocusta migratoria.     

Direct observation of freeze-thaw instability of latex coatings via high pressure freezing and cryogenic SEM

Despite its industrial importance, the subject of freeze-thaw (F/T) stability of latex coatings has not been studied extensively. There is also a lack of fundamental understanding about the process and the mechanisms through which a coating becomes destabilized. High pressure (2100 bar) freezing fixes the state of water-suspended particles of polymer binder and inorganic pigments without the growth of ice crystals during freezing that produce artifacts in direct imaging scanning electron microscopy (SEM) of fracture surfaces of frozen coatings. We show that by incorporating copolymerizable functional monomers, it is possible to achieve F/T stability in polymer latexes and in low-VOC paints, as judged by the microstructures revealed by the cryogenic SEM technique. Particle coalescence as well as pigment segregation in F/T unstable systems are visualized. In order to achieve F/T stability in paints, latex particles must not flocculate and should provide protection to inorganic pigment and extender particles. Because of the unique capabilities of the cryogenic SEM, we are able to separate the effects of freezing and thawing, and study the influence of the rate of freezing and thawing on F/T stability. Destabilization can be caused by either freezing or thawing. A slow freezing process is more detrimental to F/T stability than a fast freezing process; the latter actually preserves suspension stability during freezing. Presented at the 82nd Annual Meeting of the Federation of Societies for Coatings Technology, October 27–29, 2004 in Chicago, IL. Tied for first place in The John A. Gordon Best Paper Competition.     

Ethanol and (−)-α-Pinene: Attractant Kairomones for Bark and Ambrosia Beetles in the Southeastern US

In 2002–2004, we examined the flight responses of 49 species of native and exotic bark and ambrosia beetles (Coleoptera: Scolytidae and Platypodidae) to traps baited with ethanol and/or (−)-α-pinene in the southeastern US. Eight field trials were conducted in mature pine stands in Alabama, Florida, Georgia, North Carolina, and South Carolina. Funnel traps baited with ethanol lures (release rate, about 0.6 g/day at 25–28°C) were attractive to ten species of ambrosia beetles (Ambrosiodmus tachygraphus, Anisandrus sayi, Dryoxylon onoharaensum, Monarthrum mali, Xyleborinus saxesenii, Xyleborus affinis, Xyleborus ferrugineus, Xylosandrus compactus, Xylosandrus crassiusculus, and Xylosandrus germanus) and two species of bark beetles (Cryptocarenus heveae and Hypothenemus sp.). Traps baited with (−)-α-pinene lures (release rate, 2–6 g/day at 25–28°C) were attractive to five bark beetle species (Dendroctonus terebrans, Hylastes porculus, Hylastes salebrosus, Hylastes tenuis, and Ips grandicollis) and one platypodid ambrosia beetle species (Myoplatypus flavicornis). Ethanol enhanced responses of some species (Xyleborus pubescens, H. porculus, H. salebrosus, H. tenuis, and Pityophthorus cariniceps) to traps baited with (−)-α-pinene in some locations. (−)-α-Pinene interrupted the response of some ambrosia beetle species to traps baited with ethanol, but only the response of D. onoharaensum was interrupted consistently at most locations. Of 23 species of ambrosia beetles captured in our field trials, nine were exotic and accounted for 70–97% of total catches of ambrosia beetles. Our results provide support for the continued use of separate traps baited with ethanol alone and ethanol with (−)-α-pinene to detect and monitor common bark and ambrosia beetles from the southeastern region of the US.     

Methyl 2,4,6-decatrienoates Attract Stink Bugs and Tachinid Parasitoids

Halyomorpha halys (Stål) (Pentatomidae), called the brown marmorated stink bug (BMSB), is a newly invasive species in the eastern USA that is rapidly spreading from the original point of establishment in Allentown, PA. In its native range, the BMSB is reportedly attracted to methyl (E,E,Z)-2,4,6-decatrienoate, the male-produced pheromone of another pentatomid common in eastern Asia, Plautia stali Scott. In North America, Thyanta spp. are the only pentatomids known to produce methyl 2,4,6-decatrienoate [the (E,Z,Z)-isomer] as part of their pheromones. Methyl 2,4,6-decatrienoates were field-tested in Maryland to monitor the spread of the BMSB and to explore the possibility that Thyanta spp. are an alternate host for parasitic tachinid flies that use stink bug pheromones as host-finding kairomones. Here we report the first captures of adult and nymph BMSBs in traps baited with methyl (E,E,Z)-2,4,6-decatrienoate in central Maryland and present data verifying that the tachinid, Euclytia flava (Townsend), exploits methyl (E,Z,Z)-2,4,6-decatrienoate as a kairomone. We also report the unexpected finding that various isomers of methyl 2,4,6-decatrienoate attract Acrosternum hilare (Say), although this bug apparently does not produce methyl decatrienoates. Other stink bugs and tachinids native to North America were also attracted to methyl 2,4,6-decatrienoates. These data indicate there are Heteroptera in North America in addition to Thyanta spp. that probably use methyl 2,4,6-decatrienoates as pheromones. The evidence that some pentatomids exploit the pheromones of other true bugs as kairomones to find food or to congregate as a passive defense against tachinid parasitism is discussed.     

2007～2008年世界塑料工业进展

收集了2007年7月～2008年6月世界塑料工业的相关资料,介绍了2007～2008年国外塑料工业的发展情况,提供了世界塑料产量、消费量及全球各类树脂的需求量及产能情况.按通用热塑性树脂(聚乙烯、聚丙烯、聚苯乙烯、聚氯乙烯、ABS树脂)、工程塑料(尼龙、聚碳酸酯、聚甲醛、热塑性聚酯、聚苯醚)、特种工程塑料(聚苯·硫醚、液晶聚合物、聚醚醚酮)、通用热固性树脂(酚醛、聚氨酯、不饱和聚酯树脂、环氧树脂)不同品种的顺序,对树脂的产量、消费量、供需状况及合成工艺、产品应用开发、树脂品种的延伸及应用的进一步扩展等技术作了详细介绍.     

2005～2006年国外塑料工业进展

收集了2005年7月～2006年6月国外塑料工业的相关资料,介绍了2005—2006年国外塑料工业的发展情况。提供了世界塑料产量、消费量及全球各类树脂生产量以及各国塑料制品的进出口情况。作为对比,介绍了中国塑料的生产情况。按通用热塑性树脂（聚乙烯、聚丙烯、聚苯乙烯、聚氯乙烯、ABS树脂）、工程塑料（聚酰胺、聚碳酸酯、聚甲醛、热塑性聚酯、聚苯醚）、通用热固性树脂（酚醛、聚氨酯、不饱和树脂、环氧树脂）、特种工程塑料（聚苯硫醚、液晶聚合物、聚醚醚酮）的品种顺序,对树脂的产量、消费量、供需状况及合成工艺、产品开发、树脂品种的延伸及应用的扩展作了详细的介绍。