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。     

以ZIF-8为前驱体制备ZnO-TiO2复合材料及其敏化太阳能电池性能的研究

通过硝酸锌与2-甲基咪唑反应制备沸石咪唑酯骨架结构材料(ZIF-8),利用钛酸正四丁酯在ZIF-8表面水解得到ZIF/TiO2复合材料。在空气气氛中于不同温度条件下对ZIF/TiO2复合材料进行热处理得到不同的ZnO/TiO2复合材料,并应用于DSSC的光阳极,测试电池的光电流-光电压特征曲线,对测试结果进行分析。结果表明:不同ZnO/TiO2复合材料为光阳极材料制备的DSSC,光电转换效率与直接热处理制备的ZnO单相材料相比有了显著提高,其中热处理温度为600℃时,材料具备最高的光电转换效率,为3.69%,比直接热处理制备的ZnO单相材料0.78%的光电转换效率提高了373%,说明加入TiO2制备复合材料可以大幅度提高ZnO基DSSC的光电性能。     

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。     

质子钛酸盐热解TiO_2纳米棒的光电性能研究

采用水热法制备钛酸盐纳米棒,在300、500和700℃下煅烧得到了TiO2纳米棒。采用扫描电子显微镜、透射电子显微镜及X-射线衍射法对所得样品进行了结构表征。将所得TiO2纳米棒作为光阳极组装成染料敏化太阳电池。电流-电压曲线测试表明700℃烧结所得样品的光电性能最优。采用电化学阻抗谱(EIS)、强制光电流谱(IMPS)和强制光电压谱(IMVS)进一步研究TiO2膜电极的动力学过程。结果显示,700℃烧结所得样品制作的电池较其它温度的电池具有更低的电荷转移阻抗、更短的电子转移时间和更长的电子寿命,暗示了其优良的电子传输动力学性能以及更高的电荷收集效率。     

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.     

基于TiO2/多壁碳纳米管复合光阳极和SnO2/多壁碳纳米管非铂对电极的染料敏化太阳能电池电子传输的改善EI北大核心CSCD

为了提高TiO2光阳极的电子传输速率,在TiO2中负载了多壁碳纳米管(MWCNTs)。采用溶胶–凝胶水热法制备了TiO2/MWCNTs复合溶胶,利用电流体动力学方法制备了均匀的TiO2/MWCNTs复合薄膜,并用TiCl4对薄膜进行了优化。用扫描电子显微镜、透射电子显微镜、X射线衍射仪和紫外可见吸收光谱仪对样品进行了表征分析。利用电化学阻抗谱和电流密度–电压曲线分析了基于TiO2/MWCNTs复合光阳极和SnO2/MWCNTs对电极的染料敏化太阳能电池(DSSC)的光电性能。结果表明,MWCNTs的加入极大地加速了电子在薄膜中的传输,减少了电子与氧化态染料和I3–的复合;基于CNT-0.12(质量分数0.12%)复合光阳极的DSSC性能最佳(VOC=0.70 V,JSC=13.0 m A/cm2,ηFF=0.64,η=5.80%),与基于纯TiO2光阳极的DSSC(η=4.44%)相比,能量转换效率提高了30.6%。     

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。     

葡萄皮天然色素在染料敏化太阳能电池中的应用

以葡萄皮乙醇提取液作为敏化剂用于染料敏化太阳能电池,光电转换效率达到0.81%。不同pH值下,葡萄皮色素敏化的光阳极的单色光光电转换效率相差较大。在酸性介质中的吸光谱能较好的满足太阳能电池对吸光的需求。采用稀盐酸处理阳极膜的方法,使染料与膜结合性能提高。光子捕获能力增强,电池的TiO2/染料/电解质界面间电子传输阻抗减小,DSSC的光电装换效率达到1.43%,电流密度和光电转换效率分别提高了48.5%和76.5%。     

导电碳黑连接TiO2和染料分子提高染料敏化太阳能电池的光电性能

通常,染料敏化纳米太阳能电池(dye-sensitized solar cells,DSSCs)使用纳米金属氧化物来作为光阳极,如纳米TiO2,作为N型半导体通过连接染料来建立光阳极的。在光阳极中金属氧化物连接染料使DSSC的吸收光谱扩展到可见光谱区。文章研究在光阳极中添加导电碳黑使其成为纳米TiO2和染料之间的纽带。实验中使用粉末涂敷法在透光率约90%导电玻璃上涂覆纳米TiO2层在450℃烧结30 min,自然冷却然后再浸在染料和碳黑的混合物中敏化制得光阳极。添加的导电碳黑起到催化剂的作用,有助于染料电子的激发和纳米TiO2导带的增加并且减小了复合阻抗。结果表明,添加0.05 g导电碳黑的DSSCs光电性能最佳。开路电压增加了约33.9%,短路电流密度从4.385 mA/cm2增加到7.637mA/cm2。     

SnO_2/RGO复合光阳极的制备及其对染料敏化太阳能电池性能的影响

采用原位化学法合成不同质量比的SnO_2/还原氧化石墨烯(RGO)纳米复合材料,通过溶胶-凝胶法制得SnO_2/RGO纳米复合薄膜光阳极。经N3染料浸渍,与Pt对电极,I~-/I_3~-电解质组装成染料敏化太阳能电池(DSSC)。对SnO_2/RGO纳米复合薄膜光阳极结构进行分析,通过伏安特性曲线分析了电池的光电性能。结果表明:石墨烯有利于提高SnO_2基DSSC的光电性能。当GO与SnCl_2·2H_2O的质量比为0.20时,电池的性能最优,短路电流密度(J(sc))和开路电压(U_(oc))分别达到15.56 mA/cm~2和0.56 V,光电转换效率为4.58%。并研究了SnO_2/RGO复合材料对光阳极的电子传输和光电转换效率的影响机制。     

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.     

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。     

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.