水热法制备Nd3+-介孔TiO2/GO复合材料及光催化性能研究

采用水热法首先制备稀土Nd3+掺杂介孔TiO2,进而复合氧化石墨烯(GO)合成了系列Nd3+-介孔TiO2/GO复合材料.通过X射线衍射(XRD)、透射电镜(TEM)、孔结构分析(BJH与BET)、X射线光电子能谱(XPS)和紫外-可见漫反射(UV-vis)等测试手段对样品的微观结构、形貌、样品表面各元素价态及谱学性质进行表征,并以甲基橙模拟污染物测试其光催化性能.结果表明,所制样品均为锐钛矿结构TiO2,晶粒尺寸在3~4 nm之间;从UV-vis测试结果分析可知,与Nd3+-介孔TiO2和TiO2/GO相比,稀土Nd3+和GO的协同效应更能有效减小TiO2半导体禁带宽度,从而增加其对可见光的吸收.此外,不同光照射下光催化降解甲基橙的实验表明,所制备样品均有较强的紫外及可见光光催化性能,其中系列Nd3+-介孔TiO2/GO复合体系可见光光催化性能更为显著.     

γ-Al2O3预处理方式对 γ-Al2O3/SAPO-34复合催化剂物化性质及催化性能的影响

采用水热包覆法制备了 γ-Al2O3/SAPO-34复合催化剂,考察了γ-Al2O3预处理方式对复合催化剂物化性质和MTO反应催化性能的影响.采用X射线衍射(XRD)、傅里叶红外(FT-IR)、扫描电子显微镜(SEM)、NH3程序升温脱附(NH3-TPD)、N2吸附脱附(BET)等手段对几种复合催化剂进行了分析表征.结果表明,γ-Al2O3预处理方式对复合催化剂物化性质和MTO催化性能影响较大.添加拟勃姆石和电位改性γ-Al2O3制得复合催化剂未形成包覆复合相结构,比表面积较小,表现出较短催化寿命,仅分别为360 min和450 min;添加γ-Al2O3制得复合催化剂形成了包覆相结构和微-介复合孔结构(微孔比表面积123.49 m2·g-1、介孔比表面积122.68 m2·g-1,总比表面积为246.17 m2·g-1,总孔容0.29 cm3·g-1),总酸量较大(0.30 mmol·g-1);在常压、反应温度380℃、进料空速2 h-1反应条件下,复合催化剂催化性能优越,稳定性良好,具有较长的催化寿命,甲醇转化率为100;,低碳烯烃选择性为88.10;,催化寿命达990 min.     

SAPO-34/CZA复合晶体相结构性质及催化CO2加氢反应研究

采用共沉淀包覆法制备了SAPO-34/CZA双功能复合催化剂,研究了复合相比例对催化剂晶体结构性质和CO2加氢制低碳烯烃催化性能的影响.采用XRD、FT-IR、SEM、BET、NH3-TPD和CO2-TPD等手段对不同催化剂的晶相组成、骨架结构、微观形貌、孔结构及表面酸碱性进行了分析表征.研究结果表明,复合相比例对SAPO-34/CZA双功能复合催化剂的结构性质和催化性能影响较大.质量比为1∶1时,制得复合催化剂具有明显微孔和介孔特征(微孔比表面积53.15 m2·g-1、介孔比表面积59.84 m2·g-1、总比表面积为113.00 m2·g-1、总孔容0.41 cm3·g-1、平均孔径14.57 nm),具有特殊包覆结构及存在复合相界面,构造了特殊反应路径,微介孔层级结构强化耦合反应,表现出较高催化性能.在还原温度285 ℃、反应温度325 ℃、压力3.0 MPa、V(H2)/V(CO2)=3.0、空速(SV)3500 mL·g-1·h-1的条件下,CO2转化率为64.80;,低碳烯烃选择性为49.68;.与物理共混催化剂SAPO-34/CZA-M相比,CO2转化率和低碳烯烃选择性分别提高了31.98;和2.43;.     

ZSM-22、β和丝光沸石介孔改性对比研究

用碱-酸处理法对ZSM-22 (TON)、β(BEA)和丝光(MOR)型沸石进行介孔改性.研究沸石结构与介孔率、脱硅选择性、介孔生成效率的关系,定量阐述了不同沸石的脱硅反应选择性、改性过程的脱硅选择性及脱硅效率.结果表明,改性沸石具有微孔-介孔结构和介孔尺度分布均一化特性.按沸石结构比较,脱硅反应选择性和改性过程脱硅选择性均满足MOR＜ BEA≤TON,且改性过程脱硅选择性均大于90.6;;与比表面相关的脱硅效率:TON＜MOR＜ BEA.沸石的骨架密度和生成焓绝对值越小、微孔可接近性越好,介孔率和脱硅效率越高.BEA型改性沸石的比表面、比孔容和介孔孔径分别为468.2 m2/g、0.66 cm3/g和5.6nm.     

硅铝胶固载掺氮TiO2介孔光催化材料的原位共生合成及表征

以硅酸钠和硫酸铝为生成硅铝胶载体的硅源和铝源,以硫酸钛为生成锐钛矿型TiO2的钛源,尿素为掺杂氮源,先通过溶胶-凝胶和水热法原位共生合成产物前躯体,再在氮气气氛下结晶化烧结制得硅铝胶固载掺氮TiO2介孔材料(N/TiO2-SiO2·Al2 O3).借助广角XRD、小角度XRD、透射电子显微镜TEM和X射线光电子能谱XPS等测试手段对所得材料进行了微观结构表征和介孔结构观察,并研究了负载量和烧结温度等条件对介孔结构状态的影响.所得结果表明,所得材料的微观结构为规整性高、尺寸约3～6 nm的网格状介孔结构聚集成尺寸约100～ 200nm团簇,而尺寸为数十纳米的锐钛矿TiO2晶粒分布在网格状介孔结构中.从增强锐钛矿的光催化效应和有利于形成介孔结构两方面优化,TiO2的负载量以摩尔比n(Si)∶ n(Ti)=1∶(0.1 ～0.5)为适当范围.虽然锐钛矿晶型可在很宽温度范围存在于硅铝骨架结构中,但从有利于介孔结构的形成考虑650℃左右的结晶化烧结温度为最佳.     

高比表面介孔碳的制备及其对溶菌酶的吸附研究

以间苯二酚-甲醛为碳源前驱体,正硅酸乙酯为硅源前驱体,嵌段聚合物F127(PEO106PPO70PEO106)为模板剂,在酸性条件下采用三组分共组装制备了具有介孔结构的碳硅复合材料.通过NaOH清洗去除硅元素可以得到具有更高面积和孔容的介孔碳.TEM和小角XRD结果表明,添加了正硅酸乙酯后所得介孔材料由有序结构变为无序蠕虫状.介孔碳材料的比表面积由389 m2/g增加到602 m2/g,孔容由0.45 cm3/g增加到0.58 cm3/g.所得介孔材料对溶菌酶的吸附量随着介孔材料比表面积和孔容的增加而增大.纯介孔碳的吸附行为符合Langmuir等温线吸附拟合,高比表面介孔碳的吸附过程符合Freundlich等温线吸附拟合.     

沉淀pH值对SAPO-34/CZA复合催化剂物化性质及CO2加氢反应影响

研究了液相沉淀包覆工艺终点pH值对SAPO-34/CZA复合催化剂物化性质和CO2氢还原制低碳烯烃催化性能的影响.借助XRD、SEM、BET、NH3-TPD和CO2-TPD等手段对不同复合催化剂的晶相组成、微观形貌、孔结构及表面酸碱性质进行了分析表征.研究结果表明,沉淀pH值对SAPO-34/CZA复合催化剂物化性质和CO2加氢制低碳烯烃催化性能影响较大.过高或过低的沉淀pH值制得复合催化剂中SAPO-34分子筛结晶度、微孔比表面积及表面碱量均有所下降,呈现以介孔为主的孔结构特征;而当pH值为7时,制得复合催化剂形成了包覆相结构和微-介复合孔结构(微孔比表面积53.1 m2·g-1,介孔比表面积59.8 m2·g-1,总比表面积为112.9 m2·g-1,总孔容0.4 cm3·g-1,平均孔径14.6 nm);在反应温度325℃,还原温度285℃,反应压力3.0 MPa,体积比H2:CO2=3.0,空速3500 mL·g-1·h-1反应条件下,CO2转化率为64.8;,低碳烯烃选择性为49.8;.与pH=9制得催化剂比较,CO2转化率和低碳烯烃选择性分别提高了26.2;和19.2;.     

壳聚糖-F27软模板法制备孔结构可调的氮掺杂纳米介孔碳球

以壳聚糖为新的碳源和氮源的前驱体、三嵌段两亲共聚物(F127)为软模板,采用喷雾干燥和直接碳化技术成功制备了氮掺杂介孔碳纳米粒(NMCs).系统研究了模板剂用量对氮掺杂介孔碳材料孔结构和氮元素含量的影响,采用X射线衍射仪(XRD)、热失重分析仪(TGA)、傅里叶变换红外光谱(FTIR)、透射电子显微镜(TEM)、比表面积和孔径分析仪(BET)、X射线光电子能谱(XPS)等技术对氮掺杂介孔碳纳米粒子的微观形貌和结构进行了表征.分析研究结果表明,氮掺杂介孔碳材料孔隙发达,纳米粒子具有球形形貌,平均直径约为300～400 nm,具有蠕虫状介孔结构,随着模板剂用量的增加,孔径在3.05～6.09 nm逐渐增大,氮元素含量逐渐从6.324;减少为3.020;,孔容和比表面积先增加后减少,碳源和模板剂质量比在6:2时比表面积最大为868.9 m2/g,孔容为0.963 cm3/g.同时掺N后的介孔碳由于掺氮量不同,接触角随着氮含量的增加而减少.     

介孔石墨相氮化碳制备及其催化应用研究进展

石墨相氮化碳(g-C3N4)是一种新型的非金属半导体光催化剂,具有良好的热稳定性和化学稳定性.近年来,许多研究聚焦于在g-C3N4基体中构建介孔结构.此类介孔石墨相氮化碳(mpg-C3N4)具有较大比表面积,并在催化领域得到广泛应用.本文综述了mpg-C3N4的结构、制备方法,并详细介绍了mpg-C3N4在催化领域的应用.未来,构建有序介孔结构及提高其光催化性能依然是mpg-C3N4领域的研究重点.     

溶剂热合成介孔氧化硅负载纳米硫化镉光催化剂及其光催化性能研究

以St(o)ber法合成的介孔氧化硅为载体,通过溶剂热法合成了介孔氧化硅负载纳米CdS光催化剂.利用XRD、SEM、比表面仪等分析手段对其结构和形貌进行了表征,并研究了其光催化性能.结果表明:介孔二氧化硅负载的纳米硫化镉为六方晶型,其颗粒尺寸约为20～30 nm.纳米CdS被负载后堵塞了二氧化硅的部分介孔孔道,致使其比表面积从590.5 m2/g下降到497.7 m2/g,孔体积也明显下降.利用介孔氧化硅负载纳米硫化镉作为光催化剂可见光光降解罗丹明B的实验结果表明,由于其介孔结构而使其对罗丹明B有较强吸附,从其光催化反应动力学方程可以看出纳米CdS被介孔二氧化硅负载后提高了其光催化反应速率.     

Sol-gel synthesis and characterization of adsorbent and photoluminescent nanocomposites of starch and silica

Using sol-gel method, mesoporous and photoluminescent silica nanocomposites of soluble starch have been synthesized and characterized. Different ratios of H₂O, TEOS and EtOH were used at fixed template (soluble starch) and catalyst (NH₄OH) concentrations to obtain materials of different performances in terms of heavy metal binding from a solution which has been monitored using Cd(II) as representative divalent heavy metal ion. Optimum material was obtained when H₂O, TEOS and EtOH were used in 14:1:2 ratio. This sample was not only an efficient metal ion adsorbent but also had an intense luminescence in ultra-violet region and potentially may be used in silicon-based UV-emitting devices. Metal binding by the material was further enhanced after calcination (at 800 °C in air) while its luminescence had a multipeak profile in UV-visible region. In a batch adsorption study, calcined hybrid composite (0.25 g/L) could remove 98.5% Cd(II) from 100 mg/L Cd(II) solution in 2 h. The chemical, structural and textural characteristics of the synthesized materials have been investigated using Fourier Transform Infrared Spectroscopy (FTIR), X-rays Diffraction (XRD), Thermal Analysis (TGA/DTA), Photoluminescence (PL), Brunauer-Emmett-Teller Analysis (BET) and Scanning Electron Microscopy (SEM).     

Syntheses and structures of N-phenylmaleimidetriazoles and by-products

The syntheses, properties, and structures of N-phenylmaleimidetriazole derivatives are described. Intermediates and by-products are also discussed. 1b. a = 43.997(7) Å, 5.7610(9) Å, 8.245(1) Å, = 99.339(4), C₂/c; 2a. a = 13.646(4) Å, b = 7.744(2) Å, c = 10.612(3) Å, = 91.979(6), P2₁/c. 3a. a = 22.245(1) Å, b = 22.245(1) Å, 10.010(1) Å, P42/n. 3a. a = 11.727(2) Å, b = 14.075(3) Å, c = 16.080(3) Å, = 105.859(3), = 105.331(3), = 98.187(3), P-1. 3b. a = 8.561(3) Å, b = 14.755(5) Å, c = 22.771(7) Å, = 97.006(5), P2₁/c. 3c. a = 10.500(2) Å, b = 12.189(2) Å, c = 13.040(2) Å, = 109.091(3), = 106.089(3), = 101.022(3), P-1. 8a. a = 16.389(8) Å, b = 5.749(3) Å, c = 19.316(3) Å, = 97.467(9), P2₁/n. 8b. a = 5.822(2) Å, b = 10.114(3) Å, c = 16.705(4) Å, = 84.681(5), = 82.840(5), = 75.769(4), P-1. 9b. a = 11.251(1) Å, 13.335(3) Å, 13.376(3) Å, = 102.456(4), P2₁/n. 9c. a = 15.836(3) Å, b = 8.236(2) Å, c = 5.447(3) Å, = 92.551(3), P2₁/c. 10a. a = 13.177(2) Å, b = 14.597(2) Å, c = 5.5505(8) Å, = 110.979(2), Cc. 11a. a = 14.720(2) Å, b = 13.995(2) Å, c = 38.245(6) Å, = 94.430(3), P2₁/n. 12b. a = 15.067(5) Å, b = 20.378(6) Å, c = 8.669(5) Å, = 99.16(4), = 99.32(3), = 105.23(3), P-1. 13b. a = 8.2824(6) Å, b = 10.5245(7) Å, c = 15.518(1) Å, = 92.305(1), = 100.473(1), = 100.124(1), P-1. 15a. a = 15.357(3) Å, b = 7.778(2) Å, c = 22.957(2) Å, Pbca. 16b. a = 18.0384(4) Å, b = 12.474(3) Å, c = 20.078(5) Å, Pbca.     

Chemistry and Electrocrystallization of Organic Metals and Superconductors

Abstract

Considerable variation in the conditions of electrochemical crystal growth of TMTSF₂X (i.e., constant current versus constant potential, ambient versus inert atmosphere, etc.) and in the purity of the constituents (donor, electrolyte, solvent) does not significantly affect the unusual low-temperature properties of this class of materials. Our results suggest that the electrocrystallization procedure may be self-purifying by selecting for conducting crystal phases with constituents having specific oxidation potentials and solubility properties. However, doping solutions with structurally and chemically similar constituents (i.e., TMTTF, and IO^? ₄ in CIO^? ₄) leads to their incorporation in the crystal structure where they have a profound effect. Several mole percent of these dopants suppress superconductivity in the PF^? ₆ and CIO^? ₄ salts, and increase and broaden the metal-insulator phase transition.     

Structural and spectral studies of N-trans-cinnamylidene-m-toluidine and N-trans-cinnamylidene-m-chloroaniline

N-trans-cinnamylidene-m-toluidine (1) C₁₆H₁₅N, and N-trans-cinnamylidene-m-chloroaniline (2) C₁₅H₁₂NCl form isomorphous crystals which are monoclinic, space group P2_l/c, with unit cell dimensionsa=5.967(2),b=13.793(3),c=15.048(5) Å, =91.97(3)° anda=5.868(2),b=13.788(4),c=15.191(4) Å, =91.87(3)°, respectively. The single-crystal X-ray structure determinations of the title compounds revealtrans structures. Ring (A) C_10–15 and ring (B) C_1–6, are practically planar in both structures with dihedral angels of 61.3(3) and 63.6(2)°, respectively.¹H nmr, u.v. and i.r. spectra are also reported.     

Crystal structure and conformational analysis of N-formyl and N-nitroso derivatives of piperidinone

Single crystal X-ray studies for N-formyl-2,6-diortho chlorophenyl-3,5-dimethyl piperidin-4-one (FOCDMPO) and N-nitroso-2,6-di(3,4,5-trimethoxyphenyl)-3,5-dimethyl piperidin-4-one (NTMPO) are reported. Crystals of FOCDMPO and NTMPO belong to the monoclinic space groups P2₁/n and C2/c, respectively. FOCDMPO: a = 9.147(2), b = 14.586(3), c = 13.665(5) Å and = 101.68(2)° NTMPO: a = 38.52(2), b = 13.727(5), c = 9.564(3) Å and = 98.60(1)°. In both the structures, the piperidine ring adopts a boat conformation with slight distortion. In FOCDMPO, one of the phenyl and methyl groups are in axial positions while the other phenyl and methyl groups are in equatorial orientations. In NTMPO, the situation is reversed. The molecules are stabilized by weak intermolecular C—H ··· O interactions in addition to van der Waals forces.     

Surface topography and crystal and domain structures of films of ferroelectric copolymer of vinylidene difluoride and trifluoroethylene

The crystallization of a copolymer from a solution at room temperature is found to lead to the formation of a metastable structure, characterized by the coexistence of ferroelectric and paraelectric phases. The fraction of the latter decreases after annealing above the Curie point. Atomic force microscopy (AFM) has revealed a difference in the surface topographies between the films contacting with air and the films contacting with a glass substrate. The microstructure of copolymer chains has been investigated by ¹⁹F NMR spectroscopy. The chain fragments with “defect” attached monomeric units are ejected to the surface. The character of the ferroelectric domains formed during crystallization and their size distribution are analyzed.

     

Isothermal and Isochronal Studies of the Structural and Electrical Properties of CdTe

Cadmium telluride (CdTe) thin films were grown by thermal evaporation technique. The influence of post‐growth heat treatment, isothermal and isochronal, on the structural and electrical properties of these films were carried out. Multi phases were obtained as a function of the period and the value of annealing temperature. In isothermal annealing, the sheet resistance was dropped by many orders while in isochronal annealing it was increased fairly. A correlation between the temperature and the annealing time and the structural characteristics of these films was established in both type of annealing. The grain size and the sheet resistance were found greatly affected by the type of annealing as well as the temperature and the annealing time.     

Optical and structral properties of pure and Ce-doped nanocrystals of barium titanate

Nanocrystals barium titanate (nc-BT) and Ce-doped barium titanate were synthesized by an unusual hydrothermal process. X-ray diffraction and Raman spectroscopy were used to investigate their microstructures, as well as their lattice vibration and photoluminescence (PL) spectra. Particle sizes as small as 20 nm were measured by X-ray diffraction pattern via Scherer equation. The critical size relative to the cubic-tetragonal transition is about 48 nm in nc-BT below which ferroelectricity vanishes. The lattice parameter ratio c/a of is equal to 1.003, much smaller than 1.01 for that of the bulk crystal, leading to a weakening of ferroelectricity. Hydroxyl defects are observed in the Ce-doped nc-BT samples which show a vibrational band at 3300 em t. Good crystallization character and the lattice perfection were characterized by Raman spectra in the nanophase barium titanate. Strong PL spectra centered at 696 and 585 nm were observed in the pure and Ce-doped nc-BT, respectively. PL dependence on temperature and annealing time was examined. A molecule-like recombination and the charge transfer between Ce⁴⁺ and Ce ³⁺ are proposed to elucidate the luminescence process in the nc-BT and Cc-doped nc-BT system.     

Structure simulation and study of electronic and dielectric properties of two derivatives of benzamide

First-principles calculations based on density functional theory have been done on the chlorinated phenyl benzamides; 4-chloro-phenyl-benzamide – C13H10ClNO, and 2-chloro-3-chloro-phenyl-benzamide – C13H9Cl2NO. The triclinic structure of 4-chloro-phenyl-benzamide and orthorhombic structure of 2-chloro-3-chloro-phenyl-benzamide have been simulated and the structural parameters have been found out. Electron density of states has been computed in the materials using the electronic structure calculation code of Quantum-Espresso which gives a band gap of 0.74 eV in case of 4-chloro-phenyl-benzamide. This value is close to the value exhibited by semiconducting materials and photonic band gap materials. Band gap in case of 2-chloro-3-chloro-phenyl-benzamide comes out to be 3.08 eV. This value is in the range exhibited by NLO materials. Dielectric constant of the materials has been computed. The value of dielectric constant in 4-chloro-phenyl-benzamide comes out to be 2.78, 3.14, and 3.92 along X, Y, and Z axes, respectively, and the average value comes out to be 3.28. The value of dielectric constant in case of 2-chloro-3-chloro-phenyl-benzamide comes out to be 1.39, 1.53, and 1.34 along X, Y, and Z axes, respectively, and the average value comes out to be 1.42. Thus, additional chlorination is increasing the band gap and decreasing the dielectric constant in phenyl benzamide.     

Structures and properties of 1,4-dithiins and related molecules

A series of organosulfur compounds was characterized by NMR, IR, mass spectroscopy, cyclic voltammetry, and chemical analyses. The crystal structures of six compounds were determined: 1,3-dithioleno[4,5-e]naphtho[2,3-b]1,4-dithiin-2,5, 10-trione (1b), P , a = 7.665(4), b = 7.997(4), c = 11.443(5) Å, = 91.311(8), = 92.516(8), = 117.53(7)° 6,7-dimethylbenzo[1,2-b]1,3-dithioleno[4,5-e]1,4-dithiin-2,5,8-trione (2b), P2₁/m, a = 3.933(1), b = 12.864(2), c = 11.943(3) Å, = 99.161(4)° 6-phenyl-2-thioxo-6-hydrocyclopenta[2,1-b]1,3-dithioleno[4,5-e]1,4-dithiin-5,7-dione (3a), C2/c, a = 32.408(6), b = 3.8743(8), c = 27.123(5) Å, = 125.171(7)° 6-phenyl-1,3-dithioleno[4,5-e]3-pyrrolino[3,4-b]1,4-dithiin-5,7-trione (3b), P2₁/n, a = 7.9712(9), b = 6.1976(7), c = 55.978(6) Å, = 91.096(1)° 2,3,7,8-tetramethylthianthrene-1,4,6,9-tetraone (4), P2₁/c, a = 4.195(1), b = 17.924(5), c = 9.682(3) Å, = 98.509(5)° 3H,6H-1,4-oxathiino[6,5-2,1]naphtho[3,4-e]1,4-oxathiin-2,7-dione (5), P2₁/n, a = 9.3522(7), b = 7.8782(6), c = 17.118(1) Å, = 93.171(1)°. Several structures exhibited significant S—S intermolecular interactions, suggesting that the molecules might be precursors for preparing nonmetallic conductors.