有机阳离子对卤素钙钛矿太阳能电池性能的影响

采用第一性原理计算了CH_3NH_3PbI_3中有机部分CH_3NH_3~+和CH_3NH_3的静电特性.结果表明:CH_3NH_3~+具有强的亲电特性,CH_3NH_3的CH_3~-端具有弱亲电性,而NH_3~-端具有弱亲核性.发现在CH_3NH_3PbI_3中CH_3NH_3~+之间强静电排斥作用在相变中起着重要的作用,且在室温条件下CH_3NH_3~+在无机笼中具备活性和无序的特性,使得TiO_2/CH_3NH_3PbI_3异质结中n型TiO_2的电子通过界面扩散到CH_3NH_3PbI_3材料,并与CH_3NH_3~+结合形成CH_3NH_3,CH_3NH_3的静电特性导致在内建电场作用下更容易取向,取向的CH_3NH_3周围形成的静电场会变得更弱和更加均匀.这对无机框架上载流子的产生和传输更加有利,这样的异质结比传统的pn结具有更大优势.这是CH_3NH_3PbI_3太阳能电池高的光电转换效率的重要原因.     

二苯并噻吩在 CoMo/CNT催化剂表面上的吸附行为研究

用等体积浸渍法分别制备了碳纳米管(CNT)、活性炭(AC)、γ-Al2O3负载的CoMo加氢脱硫催化剂.用器外预硫化的方法制备了相应的硫化态的CoMo催化剂.采用程序升温脱附(TPD)技术表征了载体、负载的氧化态CoMo催化剂和硫化态CoMo催化剂的表面酸性.采用热重(TG)和XRD等分析手段研究了二苯并噻吩(DBT)在碳纳米管载体、碳纳米管负载的氧化态CoMo催化剂以及硫化态CoMo催化剂上的吸附行为.对DBT在样品表面的吸附行为与表面酸性进行了关联.研究发现DBT分子在载体、负载的催化剂表面的吸附行为遵循如下的规律硫化态CoMo催化剂对DBT的吸附能力＞相应氧化态CoMo催化剂对DBT的吸附能力≥相应载体对DBT分子的吸附能力.研究表明载体的比表面积的大小不是决定DBT吸附量的主要因素.DBT分子的吸附量与载体或催化剂的表面酸性以及其他表面性质有一定的内在联系,随着表面酸性的增强,吸附量也相应增大.加氢脱硫产物分布结果表明,DBT分子在硫化态CoMo/CNT催化剂的表面可能以端点吸附为主;而在硫化态CoMo/AC和CoMo/γ-Al2O3催化剂上存在两种竞争的吸附态,部分DBT分子端点吸附,而另一部分DBT分子倾向于平躺吸附.     

纳米氧化锌的制备新方法

使用流变相反应法，用尿素和水对原料氧化锌进行处理，在120℃左右首先制得前驱动，由IR、XRD和TG、DTA表征前驱物为Zn4CO3(OH)6.2H2O。前驱物在300℃分解1h得纳米氧化锌，用XRD和TEM对产物的组成，粒度，形貌进行表征，结果表明，产物纳米氧化锌属于六方晶系，呈球形，大小均匀，平均粒径为30nm左右。     

(NH4)2MoS4引导CdTe QDs自组装及光学性质调控和细胞成像

报道了一种简易、快速调节量子点荧光波长的方法.以GSH为配体水热法合成了发射波长为540 nm左右的绿色荧光CdTe量子点,通过（NH₄）₂MoS₄在加热和常温条件下引导CdTe量子点进行自组装.加热条件下,15 min内可以使发射波长迅速的红移100 nm以上.常温条件下,在48 h内可以缓慢的引导CdTe量子点进行自组装,发射波长缓慢红移70 nm以上.利用对比实验验证了（NH₄）₂MoS₄中的MoS₄^2-对引导CdTe量子点自组装具有特异性,并且构建了一个合理的自组装体的结构单元模型.在细胞成像领域,该自组装体具有潜在的应用前景.     

Indirect resolution of enantiomers of penicillamine by TLC and HPLC using Marfey's reagent and its variants

TLC and HPLC methods were developed for indirect chiral separation of penicillamine (3,3-dimethylcysteine) enantiomers after derivatization with Marfey's reagent (FDNP-Ala-NH(2)) and two of its structural variants, FDNP-Phe-NH(2) and FDNP-Val-NH(2). The binary mobile phase of phenol-water (3:1 v/v) and solvent combinations of acetonitrile and triethylamine phosphate buffer were found to give the best separation in normal and reversed-phase TLC, respectively. The diastereomers were also resolved on a reversed-phase C18 HPLC column with gradient elution of acetonitrile and 0.01 m trifluoroacetic acid. The results due to these three reagents were compared. The method was successful for checking the enantiomeric impurity of l-penicillamine in d-penicillamine and to check the enantiomeric purity of pharmaceutical formulations of d-penicillamine. The method was validated for linearity, repeatability, limit of detection and limit of quantification.     

Hole blocking PbI2/CH3NH3PbI3 interface

Modulated charge separation across (MO)/CH₃NH₃PbI₃ and (MO)/PbI₂/CH₃NH₃PbI₃ (MO = TiO₂, MoO₃) interfaces was investigated by surface photovoltage (SPV) spectroscopy. Perovskite layers were deposited by solution‐based one‐step preparation and two‐step preparation methods. An unreacted PbI₂ layer remained at the interface between the metal oxide and CH₃NH₃PbI₃ for two‐step preparation. For the two‐step preparation on TiO₂, the SPV signal related to absorption in CH₃NH₃PbI₃ increased in comparison to the one‐step preparation due to electron transfer from CH₃NH₃PbI₃ via PbI₂ into TiO₂ whereas the SPV signal related to defect transitions decreased. For the one‐step preparation on MoO₃, holes photogenerated in CH₃NH₃PbI₃ recombined with electrons in MoO₃. In contrast, a hole transfer from CH₃NH₃PbI₃ towards MoO₃ was blocked by the PbI₂ interlayer for the two‐step preparation on MoO₃. (© 2014 WILEY‐VCH Verlag GmbH &Co. KGaA, Weinheim)     

过渡金属离子掺杂CeO_2-SO_4~(2-)固体酸的结构、redox性能、吸附性能及NH_3-SCR活性研究

通过溶胶凝胶法制备了Cux+,Fex+,Nix+和Zrx+掺杂的CeO2-SO42-固体酸NH3-SCR催化剂。利用XRD,IR,NH3-TPD,NH3-TPO,NOx-TPD和NO-TPO等手段研究了过渡金属离子掺杂对CeO2-SO42-催化剂结构、吸附性能、redox性能和NH3-SCR活性的影响。试验结果表明,Nix+和Zrx+掺杂的CeO2-SO42-固体酸催化剂的NH3-SCR活性最好,在250～360℃温度范围内NOx的转化率可达80%以上;Cux+掺杂催化剂的NOx和NH3吸附性能较差,导致催化剂的脱硝效率较低,而Fex+掺杂催化剂虽然具有较好的NH3和NOx吸附性能,但该催化剂对NH3的氧化性能较高,导致高温条件下还原剂的氧化,从而降低了CeO2-SO42-催化剂的活性;Nix+和Zrx+掺杂可以在提高催化剂吸附性能的基础上保持较低的NH3氧化活性,从而使CeO2-SO24-催化剂保持较高的脱硝性能。     

Ab-initio density functional theory study of a WO3 NHa-sensing mechanism

WO3 bulk and various surfaces are studied by an ab-initio density functional theory technique. The band structures and electronic density states of WO3 bulk are investigated. The surface energies of different WO3 surfaces are compared and then the （002） surface with minimum energy is computed for its NH3 sensing mechanism which explains the results in the experiments. Three adsorption sites are considered. According to the comparisons of the energy and the charge change between before and after adsorption in the optimal adsorption site Olc, the NH3 sensing mechanism is obtained.     

载体对铜基催化剂NH_3-SCR低温脱硝性能的影响

采用浸渍法制备载体负载铜氧化物催化剂。通过XRD、TG-MS、XPS、NO-TPD、NH_3-TPD和H_2-TPR等手段对催化剂进行表征,考察了有氧条件下载体对催化剂NH_3-SCR低温脱硝性能的影响。结果表明,铜物种在载体上以CuO和Cu_2O形式共存,载体影响铜物种的分散性和氧化态,影响催化剂酸性、氧化还原性和对反应物的吸脱附能力。Cu/HZSM-5催化剂,铜物种分散度高,氧化还原性能好,具有适宜的酸性和酸量,对反应物有良好的吸附-脱附性能,在NH_3-SCR脱硝反应中具有较好的催化活性,反应温度低,T_(50)和T_(90)分别为137和165℃,活性窗口温度宽,NO转化率高于90%的温度为165-358℃。