石墨烯-二氧化钛纳米管催化剂的光解水制氢性能研究

为改善能源短缺,对新型光催化水解制氢材料进行了研究。通过改进Hummer法制备氧化石墨,溶胶-凝胶法制备锐钛矿型二氧化钛,采用浓碱法制得石墨烯-二氧化钛纳米管催化剂,考察了不同石墨烯的掺杂量对催化活性的影响。经过光解水制氢实验发现,掺杂不同质量分数石墨烯的催化剂催化活性得到了进一步提高,其中掺杂量为1%的产氢活性最好,产氢速率是纯二氧化钛纳米管的2. 5倍。通过BET、XRD、UV以及FT-IR等方法对催化剂进行了表征。结果表明,石墨烯与二氧化钛纳米管成功复合,并且石墨烯的掺杂在一定程度上提高了催化剂的BET比表面积;催化剂对可见光的响应范围得到进一步扩大,这为催化剂光解水制氢性能的提高提供了有力的条件。     

二氧化钛纳米管的制备、改性及应用

二氧化钛纳米管因其特殊的形貌和高度有序的特性成为了目前研究的热点之一.本文系统回顾了近年来有关二氧化钛纳米管的相关研究,着重阐述了二氧化钛纳米管的制备方法,主要包括模板法、阳极氧化法、水热法;在此基础上,详细论述了掺杂、复合等对二氧化钛纳米管进行改性的方法;并简要介绍了二氧化钛纳米管及其复合材料在环境、能源等领域的应用.最后,展望了二氧化钛纳米管的主要研究方向是对形成机理、管形貌调控、表面改性等方面做进一步研究,以期为后续的研究提供参考.     

晶种法制备3D-TNAs@NH2-MIL-125复合电极及其光电催化性能研究

以钛丝网为基底制备三维二氧化钛纳米管阵列电极(3D-TNAs),之后通过晶种滴加法将NH₂-MIL-125与三维二氧化钛纳米管阵列复合,制备3D-TNAs@NH₂-MIL-125复合电极材料。通过调节晶种时间,研究不同制备时间对复合电极表面形貌、物理化学性质及光电化学性能的影响。结果表明,通过晶种滴加法合成的3D-TNAs@NH₂-MIL-125复合电极具有优异的光电化学性能,其中晶种时间为6 h的复合电极综合性能最好,在模拟太阳光及0.7 V外加偏压的条件下,反应时间为150 min时对亚甲基蓝的降解率可达97.8%。     

Ti/TiO_2/Pd纳米电极的制备和电催化性能

采用阳极氧化法在纯钛表面生成结构高度有序的二氧化钛纳米管阵列,并通过室温固相反应制备了钯纳米颗粒。采用自组装方法将钯纳米颗粒修饰到Ti/TiO2表面制备了Ti/TiO2/Pd纳米电极。利用电子扫描显微镜、X-射线衍射分析二氧化钛纳米管、钯纳米颗粒和纳米电极的微观结构和表面形貌,并研究了Ti/TiO2/Pd纳米电极对甲醇的电催化性能。结果表明,TiO2纳米管排列整齐有序,Ti/TiO2/Pd电极中Pd纳米颗粒均匀分散在TiO2纳米管表面。电化学测试结果表明,Ti/TiO2/Pd纳米电极对甲醇的电催化氧化过程具有很好的电催化活性。     

TiO_2纳米管电极金属离子掺杂的表征

采用浸渍法对TiO2纳米管电极进行Zn2+、Fe3+、Cu2+离子的掺杂改性,并进行了各种性能表征.扫描电镜(SEM)及X射线衍射光谱(XRD)结果表明,金属离子掺杂后的TiO2纳米管电极依然保持了良好的表面形态及锐钛矿晶型,纳米管的直径为60—100 nm,其晶面主要为101面;可见紫外漫反射光谱(DRS)分析表明,进行掺杂的TiO2纳米管电极的光学性质有不同程度的改变,Zn2+、Fe3+和Cu2+掺杂的TiO2纳米管电极的禁带宽度分别为3.37 eV3、.14 eV、2.86 eV.这表明掺Cu2+的TiO2纳米管电极的吸收边带发生了明显的红移.     

CuS纳米材料的水热法制备及其光催化性质研究

以氯化铜和硫代乙酰胺为原料,聚乙二醇400(PEG400)为表面活性剂,采用水热法在160℃下反应10h成功制备了CuS纳米管和CuS纳米颗粒。用X射线粉末衍射仪(XRD)、扫描电子显微镜(SEM)、N_2吸脱附和荧光光谱仪(PL)多种手段对产品进行表征。以罗丹明B、甲基橙为目标降解物,考察了CuS纳米管和纳米颗粒的光催化活性。结果表明:所制备的产品为六方相CuS;PEG400对产品的形貌有很大影响;CuS纳米管在紫外光照射140min后对罗丹明B和甲基橙的降解率达到81.5%和87.9%,CuS纳米颗粒对罗丹明B和甲基橙的降解率约为63.5%和66.6%。CuS纳米管的光催化活性明显优于CuS纳米颗粒。     

负载金的掺氮二氧化钛的制备及其可见光催化性能

以纳米管钛酸为前驱体,采用水热法先制备得到新型N掺杂二氧化钛,然后用沉积沉淀法在N掺杂二氧化钛表面负载微量贵金属Au,制备得到负载Au的掺N二氧化钛.利用TEM、XRD、XPS、ESR和DRS等手段研究了样品的形貌、晶体结构、元素化学态和光谱吸收性质.样品光催化活性通过可见光催化降解丙烯进行评价,结果表明,样品N-TiO2和Au/N-TiO2具有明显的可见光(λ≥420 nm)催化活性.ESR结果表明,掺氮过程中生成的束缚单电子的氧空位是样品具有可见光响应的原因.     

柔性TiO2纳米管薄膜电极的制备及其光电性能

采用水热合成法制备出TiO2纳米管,通过XRD、TEM和氮气等温吸附-脱附仪等测试手段对TiO2纳米管进行了表征.用烧结的TiO2纳米管和P25粉末混合制成薄膜电极,并研究了薄膜电极的表面形貌、染料吸附量和光电性能.研究表明,加入TiO2纳米管可以制备出机械稳定的薄膜;掺杂TiO2纳米管的含量越多,薄膜电极的染料吸附量越大;掺杂5%烧结纳米管粉末的薄膜电极的光电性能最好,其短路电流可达3.25mA,光电转换效率达到1.67%.     

TiO2/CNT催化剂的制备及其光催化性能研究

采用水热法制备二氧化钛(TiO2)纳米管,采用原位沉积法将酸洗碳纳米管(CNT)与TiO2纳米管复合制备TiO2/CNT催化剂,采用扫描电子显微镜和X-射线衍射仪对其进行表征.在紫外光照射下,进行模拟罗丹明B染料废水的降解实验,研究了TiO2纳米管负载量、TiO2/CNT催化剂投加量和罗丹明B浓度等因素对降解效果的影响...     

对甲基苯磺酸钠掺杂聚吡咯/二氧化钛纳米管阵列全电池的电化学储锂性能

采用电化学方法制备了对甲基苯磺酸钠掺杂的聚吡咯(TsONa/PPy)锂离子电池正极材料和二氧化钛纳米管阵列(TiO_2NT)负极材料。利用扫描电子显微镜和X射线能量色散光谱仪研究了样品的微观结构及形貌,并进一步组装成全电池,利用恒流充–放电和循环伏安(CV)技术测试了其电化学性能。结果表明:对甲基苯磺酸钠掺杂的聚吡咯正极材料是由直径为3μm左右的微球组成,二氧化钛负极材料则呈现三维有序纳米管阵列形貌,两种电极材料的表面皆凸凹不平;由二者组成的全电池首次放电比容量约为105 mA·h/g,经过50次循环后,可逆放电比容量仍保持在65 mA·h/g,表现了良好的循环稳定性,此外还表现了良好的倍率性能。     

Many Drugs of Abuse May Be Acutely Transformed to Dopamine,Norepinephrine and Epinephrine In Vivo

It is well established that a wide range of drugs of abuse acutely boost the signaling of the sympathetic nervous system and the hypothalamic–pituitary–adrenal (HPA) axis, where norepinephrine and epinephrine are major output molecules. This stimulatory effect is accompanied by such symptoms as elevated heart rate and blood pressure, more rapid breathing, increased body temperature and sweating, and pupillary dilation, as well as the intoxicating or euphoric subjective properties of the drug. While many drugs of abuse are thought to achieve their intoxicating effects by modulating the monoaminergic neurotransmitter systems (i.e., serotonin, norepinephrine, dopamine) by binding to these receptors or otherwise affecting their synaptic signaling, this paper puts forth the hypothesis that many of these drugs are actually acutely converted to catecholamines (dopamine, norepinephrine, epinephrine) in vivo, in addition to transformation to their known metabolites. In this manner, a range of stimulants, opioids, and psychedelics (as well as alcohol) may partially achieve their intoxicating properties, as well as side effects, due to this putative transformation to catecholamines. If this hypothesis is correct, it would alter our understanding of the basic biosynthetic pathways for generating these important signaling molecules, while also modifying our view of the neural substrates underlying substance abuse and dependence, including psychological stress-induced relapse. Importantly, there is a direct way to test the overarching hypothesis: administer (either centrally or peripherally) stable isotope versions of these drugs to model organisms such as rodents (or even to humans) and then use liquid chromatography-mass spectrometry to determine if the labeled drug is converted to labeled catecholamines in brain, blood plasma, or urine samples.     

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.     

ICP-MS法测定地球化学样品中As、Cr、Ge、V等18种微量痕量元素的研究

建立了测定地球化学样品中包括As、Cr、Ge、V等18种微量、痕量元素的ICP-MS方法。地化试样用HF-HNO3混酸分解后,以1 1 HNO3溶解干渣。由于制样不使用盐酸,避免了Cl对As、Cr、Ge、V的质谱干扰。用国家一级地球化学标准物质GBW 07309制备溶液优化仪器工作参数,并用于校准。方法测定限(6s)为:0.007~6.4μg/g,精密度(RSD%,n=12)为:29%~9.4%,经过国家一级地球化学标准物质的分析验证,结果与标准值吻合。方法已应用于国土资源调查的试样分析。     

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.     

基于ATRP法制备的触角状亲水性羟胺树脂的吸硼性能的研究

以大分子引发剂氯乙酰化聚苯乙烯微球(PS-acyl-Cl)经原子转移自由基聚合(ATRP)法引发丙烯酰胺(AM)和甲基丙烯酸缩水甘油酯(GMA)单体的共聚接枝,制得一种触角状亲水性环氧载体(PS-acyl-g-P(AM-co-GMA)),再经二乙醇胺(DEA)的环氧基开环胺化反应,得到一种含多个-NCH2CH2OH螯合配基的多齿-五元螯合环的触角状亲水性羟胺树脂(PS-acyl-g-P(AM-co-GMA)-DEA)。将此树脂用于硼吸附研究,结果表明,PS-acyl-g-P(AM-co-GMA)-DEA树脂对硼的吸附满足Langmuir方程,为单分子层吸附;饱和吸附量约为37.7 mg·g-1,且树脂5 min即可达到吸附平衡,与其它已报道的吸硼树脂相比,该树脂具有更高的吸附量和吸硼速率。吸附动力学研究表明,树脂吸附硼的过程主要由颗粒扩散过程控制。重复使用5次后该树脂的吸附量基本不变,解吸率均在90%以上,重复使用性能良好。