Composition-dependent structural and electronic properties of α-(Si1−xCx)3N4

The highly unusual structural and electronic properties of the α-phase of (Si1-xCx)3N4 are determined by density functional theory (DFT) calculations using the Generalized Gradient Approximation (GGA). The electronic properties of α-(Si 1-xCx)3N4 are found to be very close to those of α-C3N4. The bandgap of α-(Si 1-xCx)3N4 significantly decreases as C atoms are substituted by Si atoms (in most cases, smaller than that of either α-Si3N4 or α-C3N4) and attains a minimum when the ratio of C to Si is close to 2. On the other hand, the bulk modulus of α-(Si1-xCx)3N 4 is found to be closer to that of α-Si3N 4 than of α-C3N4. Plasma-assisted synthesis experiments of CNx and SiCN films are performed to verify the accuracy of the DFT calculations. TEM measurements confirm the calculated lattice constants, and FT-IR/XPS analysis confirms the formation and lengths of C-N and Si-N bonds. The results of DFT calculations are also in a remarkable agreement with the experiments of other authors.

Low temperature CO oxidation and water gas shift reaction over Pt/Pd substituted in Fe/TiO2 catalysts

We demonstrate the activity of Ti0.84Pt0.01Fe0.15O2-delta and Ti0.73Pd0.02Fe0.25O2-delta catalysts towards the CO oxidation and water gas shift (VMS) reaction. Both the catalysts were synthesized in the nano crystalline form by a low temperature sonochemical method and characterized by different techniques such as XRD, FT-Raman, TEM, FT-IR, XPS and BET surface analyzer. H-2-TPR results corroborate the intimate contact between noble metal and Fe ions in the both catalysts that facilitates the reducibility of the support. In the absence of feed CO2 and H-2, nearly 100% conversion of CO to CO2 with 100% H-2 selectivity was observed at 300 degrees C and 260 degrees C respectively, for Ti0.84Pt0.01Fe0.15O2-delta and Ti0.73Pd0.02Fe0.25O2-delta catalyst. However, the catalytic performance of Ti0.73Pd0.02Fe0.25O2-delta deteriorates in the presence of feed CO2 and H-2. The change in the support reducibility is the primary reason for the significant increase in the activity for CO oxidation and WGS reaction. The effect of Fe addition was more significant in Ti0.73Pd0.02Fe0.25O2-delta than Ti0.84Pt0.01Fe0.15O2-delta. Based on the spectroscopic evidences and surface phenomena, a hybrid reaction scheme utilizing both surface hydroxyl groups and the lattice oxygen was hypothesized over these catalysts for WGS reaction. The mechanisms based on the formate and redox pathway were used to fit the ldnetic data. The analysis of experimental data shows the redox mechanism is the dominant pathway over these catalysts. Copyright (C) 2012, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights reserved.

几种稀土氟化物和氧化物纳米发光材料的制备、性能及其应用探索研究

目前，纳米材料已经应用于很多医药和生物领域，诸如临床诊断、药物传送、体内体外荧光标记等。稀土离子掺杂的纳米材料因其独特的发光性质已被认为是有前景的生物荧光标记，二氧化硅作为环境友好发光材料也受到越来越多的重视。本论文合成稀土离子掺杂的下转换和上转换发光纳米材料，并进行表面功能化，使之连接生物药物小分子，以期作为荧光标记。同时采用不同方法制备不同大小的二氧化硅球，并研究其发光性质。 采用多醇法成功地制备出结晶程度高的CeF3:Tb3+纳米粒子。氧化硅和胺基硅烷包覆使纳米粒子具有胺基功能化，然后通过SOCl2成功地活化生物素使之连接到纳米粒子上并随之与亲合素键合。胺基功能化的CeF3:Tb3+ 纳米粒子发光产生严重的猝灭，而生物分子与纳米粒子结合后发光得到很大程度上的恢复。生物功能化的CeF3:Tb3+ 纳米粒子能很好地分散在水中，为这些CeF3:Tb3+ 纳米粒子作为生物荧光探针奠定了基础。同时以P123为结构导向剂，介孔氧化硅成功地包覆CeF3:Tb3+ 纳米粒子。介孔氧化硅层存在部分有序的六方介孔体系和部分微孔结构，该复合物保持绿色荧光性质并具有相当大的孔容和大的表面积。布洛芬能载入复合物的孔道中，在24 h内释放完全。因此，这类复合物可以在靶向的药物传送体系中具有潜在的应用价值。 利用多醇法制备出NaYF4:Yb3+, Er3+ 纳米粒子。NaYF4:Yb3+, Er3+ 纳米粒子进行胺基功能化，并通过氧化寡糖链成功地活化亲合素，使之连接到胺基功能化的纳米粒子上。生物功能化的 NaYF4:Yb3+, Er3+纳米粒子仍保持较好的上转换发光性质，可以作为生物体系的荧光探针。另外用 P123作为结构导向剂和助表面活性剂PVP 或 TMB 成功地使NaYF4:Yb3+, Er3+ 纳米粒子包覆介孔氧化硅。外层氧化硅层有介孔结构。该复合物保持红色荧光性质，并具有大的孔容、表面积。布洛芬能载入复合物的孔道中，在12 h内完全释放。 通过高温溶剂法合成出YVO4:Eu3+ 纳米粒子。粒子结晶程度高，为椭球形状，长轴为80 nm，短轴为43 nm。YVO4:Eu3+ 纳米粒子的荧光发射跃迁主要源于5D0能级。FT-IR 谱和 XPS 谱表明纳米粒子表面的配体为油酸和油胺分子。Eu3+ (5D0 level) 寿命因表面有机配体的存在比体材料的寿命短。 成功地制备出不同大小的纳米至亚微米尺度且具有发光性能的单分散二氧化硅球，其尺寸随胺基浓度的增加而增大。烧结后粒子仍保持单分散性，但其尺寸缩小。烧结后的二氧化硅球含有C杂质。亚微米尺度的二氧化硅球的发射带最大值随氨丙基三乙氧基硅烷（APTES）浓度的增加而红移，但是纳米尺度的二氧化硅球的发射带最大值红移更大。单分散二氧化硅球发光原因归于二氧化硅结构中存在的碳和氧缺陷。

负载茂金属催化剂的过程开发

本工作合成了一系列新型壳核载体负载茂金属催化剂，并利用其进行了过程开发的研究；结合对气相法和淤浆法两种聚合方法的比较进行了聚合物形态的研究；最后对得到的乙烯／α－烯烃的共聚物进行了表征。主要工作如下：1）发明了一种新型的有机／无机壳核结构复合载体，以PSAm负载于SiO_2, MgCl_2等制得。探讨了不同制备条件下所得载体的化学结构与组成以及载体的形态和物理性质。SEM和图像分析表明：载体有良好的球形度以及粒径分布均匀；IR和XPS证明了聚合物在载体中的存在以及A型载体中PSAm与SiO_2以氢键相连；TGA给出了聚合物在载体中的含量。2）研究了茂金属负载催化剂的不同制备条件并对催化剂进行了表征。通过XPS对催化剂表面Zr元素结合能的分析，发现壳核载体的表面化学环境与聚合物载体类似。BET对催化剂的研究结果表明：催化剂表面积和孔度较大，有利于烯烃的聚合。表面元素分析证明聚合物上的官能团在载体表面分布均匀。最后对催化剂进行了初步的聚合实验，研究了Al/Zr比和温度对催化剂活性的影响。3）进行了催化剂的过程开发。利用实验室的微型反应器对五种催化剂进行了筛选，确定MSC－3为首选催化剂。并采用淤浆法在2L高压釜上进行了优选催化剂的小试，分析了压力和溶剂对催化剂聚合活性的影响。最后在φ100mm直径气相流化订聚合反应器上对优选催化剂进行了模式实验。实验得到了堆密度较高（0.39g/cm~3），颗粒分布均匀，粒径较大（平均560μm）的聚乙烯产物，证明了此种催化剂的工业化前景光明。并对气相法聚合所需Al/Zr比较小，α－烯烃促活效应等进行了解释。4）对茂金属催化剂所得原生态聚合物的形态问题进行了研究。发现对于均相茂金属催化体系，由其所得聚乙烯的形态是一种分形结构，符合CCA模型。而对于负载茂金属催化剂，本文通过实验对其聚合过程进行了研究，提出了一种新型的聚合模型（载体破碎多核模型）。利用该模型，并通过淤浆法和气相法两种聚合方法的比较，发现聚合体系的传热和传质效应对聚合物的形态控制有着决定性的作用。并集中探讨了催化剂的物理性质、负载的牢固程度、溶剂和聚合方法等因素对聚合物形态的影响。5）对气相法聚合所得的乙烯／α－烯烃共聚物进行了表征。从~(13)C NMR和DSC的结果发现：负载茂金属催化剂可能存在多活性中心。在共聚物分子量研究中发现不同组成聚合物特性粘数的变化异常，表明可能有长链支化存在。

在辉光放电中六甲基环三硅氧烷聚合的研究

I不同等离子气体对辉光放电聚合物淀积速率的影响 采用H_2、He、N_2、O_2和Ar作为等离子气体，在外部电极电容耦合式反应器中进行了六甲基环三硅氧烷和丙烯的等离子体聚合反应。实验结果表明，这两类性质完全不同的单体在不同等离子气体中聚合时，聚合物淀积速率的大小顺序和八氟环丁烷单体时一样，显示出某种规律性，按淀积速率大小排列，都有He > Ar，H_2 > N_2 > O_2。用磁撞理论解释这种规律时，发现等离子气体分子的质量是影响聚合物淀积速率的主要因素，计算结果和实验结果有好的一致性。II反应参数对六甲基环三硅氧烷辉光放电聚合反应规律及聚合物结构和性能的影响 采用外部电容耦合式RF辉光放电装置进行了六甲基环三硅氧烷的等离子体聚合，用IR、XPS、PGC/MS等方法对聚合物结构进行了表征，并推断了聚合反应历程。观察到使用H_2和O_2为等离子气体时，聚合物的C/Si比较高，并证实这是由于聚合物内存在较多短碳链的结果。从IR、ESR和PGC/MS结果，推断了聚合反应按三种历程进行。TG测试表明，使用惰性等离子气体或者升高放电功率可以使聚合物的热稳定性得到改进。本文还测定了聚合膜对水的接触角，并计算了聚合物的表面能，结果表明在H_2和惰性气体中制备的聚合膜有好的疏水性。III在反应性气体N_2和NH_3中D_3的辉光放电聚合反应 采用N_2和NH_3为等离子气体，在外部电极电容耦合式RF辉光放电装置中进行了六甲基环三硅氧烷的等离子体聚合。用IR、XPS等方法对聚合物结构进行了表征，并推断了N_2和NH_3参加聚合反应的机构。结果表明，N在聚合物中的存在形式为C = NH，随D_3/NH_3比的减小，聚合物的N含量增大，Si-H基团增多。在含氮气体中制备的膜都具有对基质的好的附着性。另外，本工作还进行了聚合物的热失重分析，测定了聚合物对水的接触角，计算了聚合物的表面能，结果表明，在NH_3中制备的聚合膜都具有好的疏水性。IV六甲基环三硅氧烷等离子体聚合膜的应用 在结构研究的基础上，本文讨论了六甲基环三硅氧烷等离子体聚合膜的某些应用，如耐热膜，绝缘膜等，重点讨论了在钟罩式RF辉光放电装置中制备的D_3等离子体聚合复合膜在气体分离方面的应用。结果表明，选择适当的条件可以合成耐热温度达300 ℃，对水的接触角超过100°，电阻系数达10~(19)数量级，以及α > 2，Jo_2在10~(-5)数量级的膜。光进行预处理，后进行等离子体聚合同样可以制得α > 2，Jo_2在10~(-5)数量级的气体分离膜。V等离子体聚合和等离子体曝露聚合对产物结构的影响 在外部平行板式电极的反应装置中进行了六甲基环三硅氧烷和八甲基环四硅氧烷的等离子体曝露聚合反应，并将反得聚合物与相应的等离子体聚合物作了比较。结果表明，两种单体都不能进行后聚合反应，未找出离子历程的证据，与此相反，在结构研究的基础上，提出了自由基历程，给前几部分的历程推导予以了支持。等离子体聚合为原子聚合，而等离子体曝露聚合中只有一部分为原子聚合，等离子体曝露聚合制备的产物的热稳定性比等离子体聚合物差，但线性较好。在非辉光区和弱辉光区可以制备近似结性的聚合物。本工作绝大部分内容还未有文献报导，其中I、III、IV部分还未有文献报导。

Carbon deposition behavior over copper salts of molybdovanadophosphoric acid catalyst supported by magnesia

MgO supported copper salt of molybdovanadophosphoric acid H4PMo11VO40 catalysts were prepared in alcohol by impregnation and the carbon deposition over these catalysts during the n-hexanol oxidation reaction was studied. The coke predominantly deposited on the catalyst surface in the form of CH., and it was not found that it caused the deactivation of the catalyst. The XRD, IR, XPS characterizations reveal that the Keggin structure of the CPMV was unaffected by carbon deposition. Moreover, it was shown that the supported CPMVs over the MgO surface can be beneficial to eliminate the coke. The temperature programmed oxidation (TPO) study showed that coke was formed over the catalyst on two different sites: (1) deposited on the CPMVs which can be burn off at a low temperature; (2) deposited on the MgO which could only be removed at higher temperature. The coke content reached constant with the reaction time increasing.

Synthesis and structural characterization of new tungsten(VI) complexes with polycarboxylate ligands

The reactions of (NH4)(2)WS4 and three polycarboxylate ligands {including nitrilotriacetate (nta(3-)), citrate (Hcit(3-)) and ethylenediaminetetra acetate (EDTA(4-))} in H2O/EtOH at ambient temperature have resulted in three new trioxotungsten (VI) complexes, K-3[WO3(nta)]center dot H2O 1, (NH4)(4)[WO3(cit)]center dot 2 H2O 2 and K-2(NH4)(2)[W2O6(EDTA)]center dot 4H(2)O 3, respectively. These three complexes have been characterized by IR, XPS, TGA-DTA, H-1 and C-13 NMR spectroscopy. And their structures have been determined by X-ray crystallographic studies, which confirm that I and 2 are mononuclear compounds and 3 is a binuclear compound. Each tungsten atom in 1-3 is coordinated to three unshared oxygen atoms, which adopt fac stereochemistry, while the remaining fac positions are occupied by three atoms from the ligands. The electrochemical properties of 2 and 3 have been investigated.

A new 1D metal-organic coordination polymer with blue fluorescent emission: [Cd-2(1,10 '-phen)(2)(betc)(H2O)](n)

A new coordination polymer [Cd-2(1,10'-phen)(2)(betc)(H2O)](n) (1) (betc = benzene-1,2,4,5-tetracarboxylate, 1,10'-phen = 1,10'-phenanthroline) was hydrothermally synthesized from CdCl2.2.5H(2)O, H(4)betc and 1,10'-phen at 160 degreesC. It was characterized by IR, XPS, TG and single-crystal X-ray diffraction. Compound 1 possesses infinite chair-like chains which construct 3D framework through pi-pi interactions and the hydrogen bond interactions. The fluorescent spectrum study shows that compound 1 exhibits blue fluorescent emission in the solid at room temperature.

Polypeptide modification of multiwalled carbon nanotubes by a graft-from approach

Covalent surface functionalization of carbon nanotubes with polypeptides is promising for possible medical applications. This work presents a graft-from approach to perform the polypeptide modification of multiwalled carbon nanotubes (MWTNs). The raw MWNTs are first amine-functionalized. The amine-functionalized MWNTs are then used as the initiator to initiate the ring-opening polymerization of gamma-benzyl-L-glutamate N-carboxyanhydride (BLG- NCA), to results in the polypeptide-grafted MWNTs. FT-IR, XPS, and TGA data demonstrate that the functionalization is successful. The TEM images of the products show that the thickness of the polypeptide shell of the PBLG-MWNT is about 4.5-22 nm. Using the facile route developed here, carbon nanotubes functionalized with other types of polypeptides can be easily fabricated using the corresponding NCAs.

Synthesis and characterization of a water-soluble endohedral metallofullerol

A water-soluble endohedral metallofullerol, Pr@C82Om(OH)(n)(m approximate to 10 and n approximate to 10), was successfully synthesized through the reaction of a pure endohedral metallofullerene, Pr@C-82, with a concentrated nitric acid and a subsequent hydrolysis process. The formation of endohedral metallofullerols Pr@C82Om(OH)(n) is thought to involve a NO2 radical formation step, in much the same way as the reaction of empty fullerenes. FT-IR, XPS, and LD-TOF MS techniques were employed to characterize the structure of the endohedral metallofullerol from the above reaction.

La_(2-x)(Sr,Th)_xCuO_(4±λ)系催化剂的表征及对CO+NO反应催化性能的研究

合成了x值不同的La2 -xSrxCuO4±λ( 0 .0≤x≤ 0 .1 )和La2 -xThxCuO4±λ( 0 .0≤x≤ 0 .4)两系列K2 NiF4型复合氧化物催化剂 ,用XRD和IR研究了催化剂的晶体结构 .利用化学分析和XPS等方法测定了该系列含Cu氧化物中Cu离子的平均价态、非化学计量氧 (λ)和催化剂的表面和体相组成 .通过控制B位Cu离子的价态和氧化物的非化学计量氧在一定范围内有规律的变化 ,考察对NO +CO反应的催化性能 ;利用MS TPD法研究了该系列氧化物对NO和CO +NO等小分子的吸附和活化性能 ,在此基础上探讨了含Cu的A2 BO4型复合氧化物对NO +CO反应中的催化作用本质 .发现在低温反应条件下 ,NO分子的活化是控制步骤 ,催化剂的活性与低价离子及其含量有关 .在较高反应温度下 ,NO的吸附为控制步骤 ,催化活性与氧空位有关

Catalytic oxidation of cyclohexene to cyclohexanone by a triple system in acidic aqueous acetonitrile medium

The catalytic oxidation of cyclohexene to cyclohexanone using Pd(OAc)(2)/HQ/FePc was investigated in an acidic aqueous solution of acetonitrile. The role of each component of this system in the oxidation of cyclohexene was explored by means of UV-VIS, IR, XPS spectroscopy and. cyclic voltammetry, respectively. Based on the experimental results, the mechanism of the oxidation of cyclohexene catalyzed by Pd(OAc)(2)/HQ/FePc was elucidated.

La_(2-x)Sr_xCuO_(4±λ)系列催化剂的合成、表征及NO分解催化性能的研究

合成了x值不同的 La_2.x_Sr_xCuO_(4±λ)(x=0.0—1.0)系列复合氧化物催化剂.用XRD、IR,XPS和化学分析等方法对催化剂的组成、结构进行了表征,并对NO分解的催化性能和作用机理进行了研究.结果表明:在x=0.0—1.0范围内.所有样品都具有A_2BO_4结构.发现NO分解活性与氧空位(缺陷)的浓度有关,与不同价态的Cu离子含量之间无直接关系.

甲烷氧化偶联Ti-La-Li系混合氧化物催化剂

研究了Ti-La-Li三元氧化物的组成、结构及其对甲烷氧化偶联反应的催化性能；用XRD、IR、XPS和SEM等方法对催化剂进行表征，结果表明：在Li-TixLa1-xO2系列催化剂中，随x值的不同，可生成LaTi1－yLiyO3-λ、、Li2TiO3、La0．66TiO2．993、La2O3和Li1.33Ti1.66O4几种物相，其中，钙钛矿到三元复合氧化物LaTi1-yLiyO3-λ是甲烷氧化偶联反应的主要活性相，活性位Li＋-O－-Ti3＋的形成是活性提高的主要原因．Li2TiO3和La0．66TiO2.993是深度氧化活性相，而Li1.33Ti1．66O4既无偶联活性，也无深度氧化活性.