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1.
采用简单混合法制备了一系列Bi2O3/Bi2WO6复合光催化剂. 在紫外光降解水中苯酚的过程中, Bi2O3/Bi2WO6的光催化活性随Bi2O3含量的增加呈现先增大后减小的趋势. 当Bi2O3最佳负载量等于12.5% (质量分数, w)时, 该复合光催化剂的活性大约是单一Bi2WO6的4 倍. 固体样品表征表明, Bi2O3主要以β-Bi2O3存在, 复合光催化剂是Bi2O3和Bi2WO6的简单混合物. 此外, 在电催化氧化水的过程中, β-Bi2O3/Bi2WO6薄膜电极的光电流远大于β-Bi2O3和Bi2WO6薄膜电极的光电流之和. Bi2O3对Bi2WO6光催化的促进作用是由于前者接受后者的光生空穴, 提高Bi2WO6光生载流子的分离效率, 从而加快了O2的还原和苯酚的降解. 相似文献
2.
纳米晶钛镧酸盐的水热合成和表征 总被引:7,自引:6,他引:7
报道了在TiO2-La2O3-M2O-H2O水热体系中,新型钛镧酸盐M0.5La0.5TiO3(M=La,Ag0.66Na0.33,Li0.6Na0.4)的水热合成,用XRD、SEM、TEM、ICP、DTA-TG、IR和ac阻抗分析技术进行了结构表征.讨论了水热合成反应体系pH、反应混合物的组成比以及晶化温度等因素对合成的影响.XRD分析表明,Na0.5La0.5TiO3和Ag0.33Na0.17La0.5TiO3具有立方结构,晶胞参数分别为a=0.3877nm和a=0.3890nm.Li0.3Na0.2La0.5TiO3具有正交结构,a=0.3894nm,b=0.3912nm,c=0.3890nm.TEM测定显示Na0.5La0.5TiO3和Ag0.33Na0.17La0.5TiO3是纳米尺度晶体,平均粒度分别为50nm和70nm.Li0.3Na0.2La0.5TiO3的平均粒度分布为5Lm.Ag0.33Na0.17La0.5TiO3在440℃的电导率为1.9×10-5S/cm,Li0.3Na0.2La0.5TiO3的电导率为1.5×10-6S/cm. 相似文献
3.
Sc2S@C90存在的信号已经被质谱检测到,但其结构还没有得到表征. 为了研究Sc2S@C90的结构和性质,通过密度泛函理论计算方法对Sc2S@C90的异构体进行了系统的筛选. 计算结果表明,能量最低的两个异构体分别为Sc2S@C90:99913和Sc2S@C90:99915. 对Sc2S@C90在0到4000 K温度下的相对浓度进行了评估,结果显示,Sc2S@C90:99913和Sc2S@C90:99915可以在高温下共存. 分析研究了Sc2S@C90的内嵌团簇与碳笼间的键连关系和相互作用特性. 这些研究可为Sc2S@C90的结构确定提供指导. 相似文献
4.
异质结型光催化膜的活性及其机理研究 总被引:11,自引:0,他引:11
采用浸渍提拉法制得TiO2,ZnO,Fe2O3,ZnO/TiO2,TiO2/ZnO,Fe2O3/TiO2和TiO2/Fe2O3石英玻璃基底负载膜.光催化降解亚甲基蓝实验表明,TiO2和ZnO具有良好的光催化活性,Fe2O3活性较差.但形成异质结后,TiO2和Fe2O3的光催化降解能力发生明显的变化.用254nm紫外光光照后,TiO2,ZnO和Fe2O3等3种氧化物膜与水的接触角均有不同程度的降低,TiO2表现出超亲水性,ZnO/TiO2和Fe2O3/TiO2膜与水的接触角小于对应的单纯ZnO和Fe2O3膜与水的接触角,其中Fe2O3/TiO2表面出现超亲水性.瞬态光电导谱的少数载流子寿命的测定表明,异质结势垒电场能有效地增强光生电子-空穴对的分离效率.根据能带理论建立的两组异质结能带模型可合理地解释实验结果. 相似文献
5.
本文采用X射线光电子能谱技术研究了两种照相明胶与化学增感剂相互作用的机理.当两种照相明胶样品在HAuCl4溶液中反应5min后,明胶中的蛋氨酸、蛋氨酸亚砜均被氧化为蛋氨酸砜.与此同时,明胶吸附的大部分Au3+被还原为Au+,并且Au+以络合形态存在于明胶之中.根据与AuCl3反应之后明胶中Au3+与Au+的比例,法国明胶的还原性略高于包头明胶.添加到明胶中的Na2S2O3能将明胶大分子所含的蛋氨酸亚砜全部还原为蛋氨酸.S2O32-、蛋氨酸和蛋氨酸砜可以稳定共存于明胶体系之中,外加的S2O32-的还原性高于明胶中蛋氨酸、蛋氨酸亚砜的还原性.添加Na2S2O3后的两种照相明胶均可以将其溶胀吸附的Au3+全部还原为胶态金.此时,参与氧化还原反应的主要基团是S2O32-而非明胶中的蛋氨酸残基.由于Na2S2O3的添加,照相明胶对AuCl3的还原能力增强. 相似文献
6.
在Ti基体上,采用电沉积法制备了镨和聚乙烯吡咯烷酮(PVP)掺杂的Ti/SnO2-Sb2O3/Pr2O3-PVP-PbO2 电极. SEM显示Ti/SnO2-Sb2O3/Pr2O3-PVP-PbO2 电极表面颗粒细化,镀层结构更加致密和均匀,XRD 测试表明掺杂使可以使电极的表面颗粒变小.循环伏安 (CV)分析表明共掺杂改性后的电极电催化活性明显提高.强化寿命测试显示Ti/SnO2-Sb2O3/Pr2O3-PVP-PbO2 电极稳定性更好,使用寿命更长. 将所制备的电极应用于亚甲基蓝(MB)模拟染料废水的降解测试,与常规的Ti/PbO2 电极相比,Ti/SnO2-Sb2O3/Pr2O3-PVP-PbO2 电极对亚甲基蓝具有更好的脱色率和 COD 除去率. 降解120min 后,对30 mg·L -1 亚甲基蓝的去除率分别可达到99%,对COD去除率为87.9%. 相似文献
7.
有机-无机卤化物钙钛矿是一类优异的光电材料. 在过去四年内, 基于有机-无机卤化物钙钛矿的光电器件实现了超过15%的光电转换效率. 而有机-无机卤化物钙钛矿材料的可控制备是保证其在光电器件中应用的基础. 本文采用新的沉积方法在玻璃衬底表面制备了一种典型的有机-无机卤化物钙钛矿CH3NH3PbI3薄膜. 其制备过程是: 采用超声辅助的连续离子吸附与反应法在玻璃衬底表面沉积PbO-PbI2复合物膜, 之后与CH3NH3I蒸汽在110 ℃环境下反应, 将PbO-PbI2复合物膜转化成CH3NH3PbI3钙钛矿薄膜. 对CH3NH3PbI3薄膜的微观结构, 结晶性及其光电性能等进行了表征. 结果表明, CH3NH3PbI3薄膜呈晶态, 具有典型的钙钛矿晶体结构. 薄膜表面形貌均匀, 晶粒尺寸超过400 nm. 在可见光范围, CH3NH3PbI3薄膜透过率低于10%, 能带宽度为1.58eV. 电学性能研究表明CH3NH3PbI3薄膜表面电阻率高达1000 MΩ. 高表面电阻率表明CH3NH3PbI3薄膜具有一定的介电性能, 其介电常数(εr)在100 Hz时达到155. 本研究提出了一种制备高质量CH3NH3PbI3钙钛矿薄膜的新方法, 所得CH3NH3PbI3薄膜可望在光、电及光电器件中得到应用. 相似文献
8.
丙烷氧化脱氢催化剂V2O5/MPO4(M=Al,Zr,Ca)的研究 总被引:9,自引:2,他引:7
制备了3种磷酸盐(MPO4,M=Al,Zr,Ca)载体,并在其上负载0.6%~6.0%的V2O5.活性评价结果表明,负载型V2O5/MPO4催化剂在丙烷氧化脱氢反应中具有良好的催化性能.丙烯选择性按V2O5/Ca3(PO4)2>V2O5/Zr3(PO4)4>V2O5/AlPO4顺序降低,这与载体的碱性强弱顺序变化一致.载体的性质和钒的负载量影响催化剂的氧化还原性能.ESR结果表明,V4+离子能可逆存在于催化剂中,暗示V5+/V4+氧化还原偶参与了氧化还原反应. 相似文献
9.
合成了五种多金属氧酸盐. 以B16小鼠黑色素瘤细胞为模型, 用噻唑蓝(MTT)法检测细胞存活率, 酶标法测定抗氧化活性和内黑色素含量及酪氨酸酶活性, 最后用分子对接模拟多金属氧酸盐和酪氨酸酶结合的机制. 研究结果表明, 两种磷钼酸(H7[P2Mo17VO62]和H8[P2Mo16V2O62])是高效的黑色素生成抑制剂, 在200 μmol/L的浓度下对黑色素合成的抑制率为74.40%和75.14%, 对细胞内酪氨酸酶活性的抑制率为35.71%和40.00%, 随着钒原子取代个数的增加, 两种抑制活性均逐渐降低. H7[P2Mo17VO62]和H8[P2Mo16V2O62]对细胞没有毒性. 两种多酸都有较好的1,1-二苯基-2-三硝基苯肼(DPPH)清除能力, IC50分别为1.683和2.800 mg/mL. 分子对接分数低于–146 kJ/mol. 综上所述, H7[P2Mo17VO62]和H8[P2Mo16V2O62]能抑制B16细胞黑色素的生成, 其机制与抑制酪氨酸酶的活性有关. 相似文献
10.
CeO2具有良好的赝电容, 但有关碳/CeO2复合材料的电化学性能有待改善. 本工作采用简单的微波辅助合成法, 将氧化石墨烯与Ce(NO3)3混合发生氧化还原反应, 获得还原氧化石墨烯(rGO)/CeO2复合材料. 通过形貌观察, CeO2以颗粒形式均匀分布在褶皱的rGO上, 且沿着rGO表面仿形生长; 纳米级CeO2颗粒之间存在微小间隙. N2吸/脱附测试结果表明, rGO/CeO2具有大的比表面积和介孔孔径, 有益于与电解液充分接触. 通过电化学测试, rGO/CeO2的比电容高达468 F•g-1, 经过10000次充放电循环, 电容保持率高达107.3%. 优异的循环稳定性归因于大表面积的rGO与均匀薄层的CeO2良好的协同效应减少了离子传输的阻力以及CeO2颗粒之间微小的间隙, 缓解了Ce4+还原为Ce3+过程中发生的晶格膨胀. 将rGO/CeO2组装成对称型超级电容器rGO/CeO2||rGO/CeO2获得的能量密度达18.16 Wh•kg-1. rGO/CeO2作为超级电容器电极材料具有广阔前景. 相似文献
11.
A new terthiophene monomer: 3',4'-dimethoxy-2,2':5',2"-terthiophene (TMT) was synthesized and characterized by 1H-NMR, 13C-NMR and FTIR. The solid-state oxidative polymerizations of TMT were performed in various ratios of oxidant (FeCl?) to monomer (TMT). The resulting polymers were characterized by 1H-NMR, FTIR, UV-vis-NIR, GPC, X-ray diffraction, CV, as well as TGA and conductivity measurements. The structure and properties of poly (TMT) were compared with those of polyterthiophene [poly(TT)] and poly (3',4'-ethylenedioxy-2,2':5',2"-terthiophene) [poly(TET)] prepared under the same polymerization conditions. After comparative analysis with poly(TT) and poly(TET), the effects of the dimethoxy substituent and FeCl? on the structural and physicochemical properties of the poly(TMT)s were discussed in depth. The comparison suggested that the dimethoxy-substituted polymer did not display higher crystallinity, thermal stability, conductivity and electrochemical activity than ethylenedioxy substituted one. The results also showed that the effect of FeCl? on poly(TMT) was similar that seen with the poly(TT), in which the oxidation degree, electrochemical activity and conductivity increased steadily with increasing [FeCl?/[TT] ratio. Furthermore, the poly(TMT) and poly(TT) are mostly made up of dimers with a small amount of higher molecular weight components. 相似文献
12.
Koren AB Curtis MD Francis AH Kampf JW 《Journal of the American Chemical Society》2003,125(17):5040-5050
Syntheses are reported of new 4,4'-dialkyl-2,2'-bithiazole oligomers that have alkenoxy side chains that are capable of easy conversion to oligomers with functionalized side chains, e.g., terminally substituted hydroxy chains. The crystal structures of two representative oligomers (4,4',4' ',4' "-tetra-(2-propenoxymethyl)-2,2',5',5' ',2' ',2' "-quaterthiazole (3P2) and 4,4',4' ',4' "-tetra-(3-hydroxypropyloxymethyl)-2,2',5',5' ',2' ',2' "-quaterthiazole (3H2)) were determined; 3P2 crystallizes in a pi-stacked motif with two molecules per unit cell, whereas 3H2 forms pi-stacks that are linked with hydrogen bonds to form infinite two-dimensional sheets with one molecule per unit cell. A comparison of the UV-vis spectra of the compounds in solution and in the solid state provides unequivocal evidence for the presence of a Davydov splitting, W(D) approximately 0.2 eV, in solid 3P2. The spectra are interpreted in the framework of molecular exciton theory to extract a value of the intermolecular transfer integral, J approximately 0.2 eV, for a total exciton bandwidth of ca. 0.8 eV. Monte Carlo calculations were used to determine the density of states of the exciton band and the absorption and emission line shapes of the 0 <-- 0 transition. It is suggested that the "three-humped" absorption profile typical of partially crystalline, regioregular polymers is the "optical signature" of pi-stacking. 相似文献
13.
分别以Fe(Cl O4)3、FeCl3、Fe2(SO4)3作为氧化剂,对3′,4′-乙撑二氧-2,2′∶5′,2″-三噻吩(TET)进行了化学氧化聚合,并研究了聚合条件对聚合物结构和电化学性能的影响。利用红外光谱、紫外光谱、X射线衍射对聚合物进行了表征,采用循环伏安、恒电流充放电等电化学方法研究了聚合物的电化学性能。结果表明:当TET与Fe(Cl O4)3的摩尔比为1∶4,反应温度为18℃,反应时间为12 h时,聚3′,4′-乙撑二氧-2,2′∶5′,2″-三噻吩(PTET)具有更好的共轭结构和电化学性能,导电率可达1.47 S/m,比电容可达133 F/g。 相似文献
14.
Datcu A Roques N Jubera V Imaz I Maspoch D Sutter JP Rovira C Veciana J 《Chemistry (Weinheim an der Bergstrasse, Germany)》2011,17(13):3644-3656
A series of isostructural open-framework coordination polymers formulated as [Ln(dmf)(3)(ptmtc)] (Ln = Sm (1), Eu (2), Gd (3), Tb (4), Dy (5); PTMTC = polychlorotriphenylmethyl tricarboxylate) and [Ln(dmf)(2)H(2)O(αH-ptmtc)] (Ln = Sm (1'), Eu (2'), Gd (3'), Tb (4'), Dy (5')) have been obtained by treating Ln(III) ions with PTMTC ligands with a radical (PTMTC(3-)) or a closed-shell character (αH-PTMTC(3-)). X-ray diffraction analyses reveal that these coordination polymers possess 3D architectures that combine large channels and fairly rare lattice complex T connectivity. In addition, these compounds show selective framework dynamic sorption properties. For both classes of ligands, the ability to act as an antenna in Ln sensitization processes has been investigated. No luminescence was observed for compounds 1-5, and 3' because of the PTMTC(3-) ligand and/or Gd(III) ion characteristics. Conversely, photoluminescence measurements show that 1', 2', 4', and 5' emit dark orange, red, green, and dark cyan metal-centered luminescence. The magnetic properties of all of these compounds have been investigated. The nature of the {Ln-radical} exchange interaction in these compounds has been assessed by comparing the behavior of the radical-based coordination polymers 1-5 with those of the compounds with the diamagnetic ligand set. While antiferromagnetic {Sm-radical} interactions are found in 1, ferromagnetic {Ln-radical} interactions propagate in the 3D architectures of 3, 4, and 5 (Ln = Gd, Tb, and Dy, respectively). This procedure also provided access to information on the {Ln-Ln} exchange existing in these magnetic systems. 相似文献
15.
Chen J Murphy AR Esteve J Ogletree DF Salmeron M Fréchet JM 《Langmuir : the ACS journal of surfaces and colloids》2004,20(18):7703-7710
The oligothiophene derivative 4-(5' " '-decyl-[2,2';5',2' ';5' ',2' ";5' ",2' " '] pentathiophen-5-yl)-butyric acid (D5TBA) was synthesized by Stille cross-coupling methods using functionalized thiophene monomers. The structural and mechanical properties of D5TBA self-assembled monolayers on mica have been studied by atomic force microscopy (AFM). The self-assembled films were prepared by immersing the mica in dilute chloroform or tetrahydrofuran (THF) solutions. The films were predominantly of monolayer thickness with molecules packed in nearly upright orientations. In regions covered with multilayers, the molecules in each monolayer were oriented opposite to those in the neighboring ones, that is, with COOH-COOH and CH3-CH3 contact. The nature of the end group in contact with the substrate depended on the solvent used and the degree of hydration of the substrate, with hydrophobic chloroform solvent favoring the methyl end down and hydrophilic THF favoring the acid group end down. The orientation could also be controlled by dipping using the Langmuir-Blodgett technique. 相似文献
16.
Ben-zhong Tang Xiang-xing Kong Xin-de Feng Department of Chemistry Hong Kong University of Science & Technology Clear Water Bay Kowloon Hong Kong China Department of Polymer Science & Engineering College of Chemistry Peking University Beijing China 《高分子科学》1999,(3):289-294
A new liquid crystalline polyacetylene containing a phenyl benzoate mesogen (5) is synthesized,whose mesomorphic properties are found to be easily "tunab1e" by simple mechanical perturbation. Thepolymerization of 10- [ 4 - (4' -methoxyphenoxycarbonyl )phenoxycarbonyl] - 1 -decyne (4 ) in itiated by theWCl_6-Ph_4Sn/dioxane complex yields polymer 5 with a M_w of 28400. The molecular structure of 5 ischaracterized by NMR, IR, and UV spectroscopy and its liquid crystalline behavior is investigated by DSC,POM, and XRD analysis. Upon mechanical perturbation, 5 exhibits unusual agitation-induced high-strengthdisclinations, shear-induced inversion walls, and solidification-induced banded textures. Such phenomenahave been observed in the main-chain liquid crystalline polymers with rigid backbones, but have seldom beenreported for the side-chain liquid crystalline polymers with flexible backbones, suggesting that the rigidpolyacetylene backbone of 5 plays a constructive role in inducing the novel molecular alignments. 相似文献
17.
Soluble conducting polymers of 3-hexylthiophene, 3-octylthiophene, 3-decylthiophene and 3-dodecylthiophene were synthesized by constant potential electrolysis. The resultant polymers were characterized by cyclic voltammetry, ultraviolet spectroscopy, thermogravimetric analysis and differential scanning calorimetry. Molecular weights were studied with gel permeation chromatography on solutions of the polymers in toluene. Surface properties were investigated by scanning electron microscopy. Substituent groups lengths have been found to strongly influence the electronic properties of the resultant polymers. Poly(3-hexylthiophene) has shown the highest conductivity, with the highest degree of polymerization. The conductivity and the degree of polymerization values decrease as the substituent chain length increases.H.B. Mark Jr.: deseased 相似文献
18.
Byrne PD Müller P Swager TM 《Langmuir : the ACS journal of surfaces and colloids》2006,22(25):10596-10604
A series of 2,5-thiophene-substituted 1',2',3',4',5'-pentamethylazaferrocene complexes were synthesized and electropolymerized to produce polymers with fully pi-conjugated backbones. The length and hence oxidation potential of the conjugated linker (the thiophene fragments) between the metal centers were varied to understand the influence of the metal-metal interactions on the overall electroactivity of the resulting polymer. These complexes were electrochemically polymerized, and the resulting polymers were characterized by cyclic voltammetry, in situ conductivity, and spectroelectrochemistry measurements. The iron-centered oxidations significantly increased the conductivity of the polymer. The results reveal that shorter conjugated linkers cause the onset of conductivity to occur at lower potentials. This effect implies that a superexchange mechanism is likely operative in the charge migration of these polymers. 相似文献
19.
《中国科学:化学(英文版)》2017,(1)
A couple of novel electrochromic materials poly(2,3,4,5-tetrakis(2,3-hydrothieno[3,4-b]dixin-5-yl)-1-methyl-1H-pyrrole)(P(t-EDOT-mPy))and poly(5,5',5",5'"-(thiophene-2,3,4,5-tetrayl)tetrakis(2,3-dihydrothieno[3,4-b][1,4]dioxine))(P(t-EDOTTh))are electrodeposited via multi-position polymerization of their tetra-EDOT substituted monomers t-EDOT-mPy and t-EDOT-Th,respectively.Compared with the linear 2D structured poly(thiophene)(E_g=2.2 eV)and poly(2,5-bis(2,3-dihydrothieno[3,4-b][1,4]dioxin-5-yl)thiophene)(E_g=1.7eV),P(t-EDOT-Th)(E_g=1.62eV)has the lowest band gap.Hence,we speculate that the band gaps of the two polymers,having 3D structures,are decreased in contrast to non-substituted polymers or bi-EDOT substituted polymers,thiophene and 1-methyl-1H-pyrrole.The results indicated that P(t-EDOT-Th)thin films are more stable and show higher transmittance amid two polymers,which may find their utilization in organic optoelectronics. 相似文献
20.
The synthesis and physicochemical properties of a new class of thiophene/arenesilole-containing pi-conjugated polymers are reported. Examples of this new polymer class include the following: poly(2,5-bis(3',3' '-dihexylsilylene-2',2' '-bithieno)thiophene) (TS6T1), poly(2,5'-bis(3' ',3' '-dihexylsilylene-2' ',2' '-bithieno)bithiophene) (TS6T2), poly(2,5'-bis(2' ',2' '-dioctylsilylene-1' ',1' '-biphenyl)thiophene) (BS8T1), and poly(2,5'-bis(2' ',2' '-dioctylsilylene-1' ',1' '-biphenyl)bithiophene) (BS8T2). Organic field-effect transistors (OFETs) with hole carrier mobilities as high as 0.02-0.06 cm2/V s in air, low turn-on voltages, and current on/off ratios >105-106 are fabricated using solution processing techniques with the above polymers as the active channel layer. OFETs based on this polymer class exhibit excellent ambient operational stability. 相似文献