Adsorption of Thiophene on Aluminum Nitride Nanotubes

Abstract

Thiophene adsorption on pristine (6,0) aluminum nitride nanotubes was studied by using density functional theory calculations, by means of B3LYP and M06-L functionals. We present the nature of the thiophene interaction in different sites of the nanotube. Adsorption energies corresponding to adsorption of thiophene are calculated to be in the range ?18.90 to ?21.06 kJ mol^{? 1} Pablo, P. C., Liprandi, D. A. and Fígoli, N. S. 1996. Ind. Eng. Chem. Res., 34: 3713–3717. [Web of Science ®] , [Google Scholar]. It has been shown that the thiophene molecule has a weak physical adsorption on the pristine models due to weak Van der Waals interaction between the nanotubes and thiophene molecule. The charge transfer between thiophene and the AlNNT is minimal and the electronic properties of the nanotubes are not affected by the thiophene adsorption. Also, with change of tube type, more efficient binding could not be achieved. The results indicate that transition metal nanoclusters are more suitable catalyst with respect to nontransition metal nanotubes in the petroleum industry.     

纳米六方相氮化铝的合成和光学性能研究

报道了以AlCl₃和Mg₃N₂为反应物, 在500 ℃条件下, 用简易的设备, 合成六方相AlN纳米材料. 样品的XRD和XPS图谱表明, 实验得到的AlN样品是纯的六方相AlN, 其中的杂质相含量均小于仪器的探测灵敏度. TEM图表明, AlN样品呈多孔网络状结构, 网络的骨架大小在10～20 nm之间. 对AlN样品的光学性能的研究表明, AlN样品的禁带宽度值约为6.12 eV; 红外吸收谱以680 cm^－1为中心形成一个很宽的红外吸收带; 其拉曼散射峰较AlN薄膜和AlN单晶向低波数方向移动.     

氯化锂插层氮化碳材料的可控制备及吸附性能

近年来, 有机废水对环境造成的污染已经引起了广泛的关注. 吸附法操作简单, 已经被广泛用于处理染料废水.通过在类石墨相氮化碳(g-C₃N₄)上用氯化锂(LiCl)插层制备了一系列Li/GCN-x复合材料, 并采用X射线衍射(XRD)、傅里叶变换红外光谱(FT-IR)、N₂-吸脱附、场发射扫描电子显微镜(SEM)以及X射线光电子能谱(XPS)等对所得吸附剂的形貌和结构进行了表征. 测试结果表明, g-C₃N₄具有明显的层状结构, 使得LiCl在层间能够稳定地生长. LiCl的加入使得g-C₃N₄晶格膨胀, 层间距扩大, 表明LiCl成功插层. 此外, 插层后Li/GCN的比表面积远大于g-C₃N₄, 扩大的比表面积以及形成的 π 共轭体系使得Li/GCN在吸附方面具有较大的潜力. 通过控制实验条件, 研究了Li/GCN对有机染料亚甲基蓝(MB)的吸附性能. 结果表明, Li/GCN-5吸附剂在pH为6时, 5 min吸附量可达704 mg•g^–1. 通过动力学拟合, Li/GCN对MB的吸附过程是由准二级动力学模型占主导地位. 进一步通过Weber-Morris模型探究吸附控制过程, 结果表明MB的吸附由表面扩散和孔内扩散共同作用, 其中表面扩散占主导, 且新增官能团与MB分子间可形成氢键, 并通过π-π键相互作用增强吸附能力. 采用共混热聚合法所制备的Li/GCN吸附剂具有稳定、均一、比表面积大等优点, 且简单快速地实现对MB的吸附, 克服了常用吸附剂动力学缓慢的缺点, 为该材料的工业化应用提供一定的借鉴.     

Cyclopentanolates of Aluminum Hydride/Aluminum Chloride forming Aluminum‐Oxygen‐Hetero‐Cages and Mixed Coordination Oligomers

Lithium aluminum hydride combined with different amounts of aluminum chloride react with cyclopentanol under the formation of compounds with aluminum‐oxygen scaffolds and hydrogen or chlorine as terminating substituents at aluminum and cyclopentyl at the oxygen atoms. H₆Al₄(OC₅H₉)₆ and Cl₆Al₄(OC₅H₉)₆, both displaying a central aluminum atom almost octahedrally coordinated by oxygen atoms of the cyclopentanolates with three AlH₂ or AlCl₂ entities bridging three oxygen edges were isolated and fully characterized. The compound dihydrido aluminum cyclopentanolate was isolated together with chloro‐hydrido aluminum cyclo‐pentanolate as a 6:2 aggregate, [H₂Al(OC₅H₉)]₆[H(Cl)Al(OC₅H₉)]₂, displaying alcoholate and hydride bridges in the crystal. Structural isomers of this compound were found in the solid. Mono‐hydrides could be isolated in the form of H₅Al₅(O)(OC₅H₉)₈ * OC₄H₁₀ and in the form of a hydride/chloride H_4.5Cl_0.5Al₅(O)(OC₅H₉)₈ * OC₄H₁₀, which is a 1:1 mixture of H₅Al₅(O)(OC₅H₉)₈ with H₄ClAl₅(O)(OC₅H₉)₈ in the crystal. In both compounds an oxygen atom is in the center of an Al₅ square pyramid. While in the first case the aluminum atom situated at the top of the pyramid has a hydride ligand, in the second case the ligand is a chloride.     

石墨相氮化碳的红外辅助微波法制备及光催化固氮性能

采用红外辅助微波法制备了可见光下具有优越固氮性能的石墨相氮化碳催化剂(g-C3N4).采用X射线衍射(XRD)、扫描电子显微镜(SEM)、透射电子显微镜(TEM)、氮气吸附、紫外-可见光谱(UV-Vis)、荧光光谱(PL)、N2-程序升温脱附(TPD)和电子顺磁共振谱(EPR)等对催化剂进行了表征.结果表明,微波处理在催化剂表面形成许多孔状结构,增大了催化剂的比表面积,抑制了催化剂光生电子-空穴的复合;微波处理还会产生大量氮空穴,这些氮空穴一方面可以吸附并活化氮气分子,另一方面可提升电荷从催化剂到氮气分子的界面转移能力,显著提高催化剂的光催化固氮性能.采用红外辅助微波法制备的g-C3N4催化剂比采用单纯微波法制备的催化剂具有更多的氮空穴,表现出更高的光催化固氮性能.     

纳米晶钛酸铅表面态对介电性能的影响

将醋酸铅、钛酸四丁酯和硬脂酸在熔融状态下混合均匀后置于冷水浴中，使其凝固成凝胶，经不同温度焙烧，制成纳米晶PbTiO3.用X射线衍射光谱、红外光谱对产物进行表征.采用X射线光电子能谱和表面光电压谱对纳米晶PbTiO3表面状态分析,发现材料表面的不完整性主要是由氧空位造成.暴露在粒子表面的主要是金属离子.随着晶粒尺寸的减小，材料表面氧空位缺陷浓度增加，表面光伏效应增强，谱带变宽.纳米晶PbTiO3材料的表面状态对其极化性质有着重要的影响，使其静态介电常数远大于常规材料的静态介电常数.     

微波消解样品-电感耦合等离子体原子发射光谱法测定锰矿中铝、镁、磷

锰矿样品在密闭的消解罐中用盐酸、硝酸、过氧化氢及氢氟酸在微波消解仪中进行消解,所得溶液移入聚四氟乙烯容量瓶中,加水定容至100mL供电感耦合等离子体原子发射光谱法分析用。此方法中不采用加入硼酸络合过剩的氢氟酸,以避免因加入硼酸而引起的干扰。为抵消基体干扰,在制备标准曲线时于各试液中加入一定量的锰(Ⅱ)溶液。选择测定铝、镁及磷的分析谱线依次为396.152,280.270,185.942nm。应用此方法分析了2件锰矿标准物质,测得上述3种元素的测定结果与认定值相符,测定值的相对标准偏差(n=11)在0.63%～1.18%之间。     

电感耦合等离子体原子发射光谱法测定轻质隔墙板中镁钙铝铁锰氯

10 g轻质隔墙板试样溶于8 mol.L-1硝酸溶液100 mL中,于此溶液中定量加入相当于氯离子估计量(物质的量)1.2倍的硝酸银溶液使其中氯离子定量生成AgCl沉淀。经陈化后,将混合物滤入于200 mL容量瓶中,加水定容。分取此溶液一份,用水稀释200倍后,用电感耦合等离子体原子发射光谱法(ICP-AES)测定其中镁、钙及银的含量。所得银的量为定量生成AgCl沉淀后留存的过量硝酸银溶液。按此银的测定值间接换算成试样中氯的含量。从上述定容为200 mL溶液中,另分取一份溶液加水稀释5倍后,按ICP-AES法测定其中痕量铝、铁及锰的含量。按所提出的方法测定了实样中镁、钙、氯及铝、铁、锰的含量,测定值的相对标准偏差(n=6)均小于2%。     

Production of Metal‐Free Composites Composed of Graphite Oxide and Oxidized Carbon Nitride Nanodots and Their Enhanced Photocatalytic Performances

A novel metal‐free composite (GN) composed of two types of carbon‐based nanomaterials, graphite oxide (GO) and 2D oxidized carbon nitride (OCN) nanodots was produced. Chemical and morphological characterizations reveal that GN contains a main component of GO with well‐dispersed 2D OCN nanodots. GN shows enhanced photocatalytic performance for degrading an organic pollutant, Rhodamine B, under visible light.     

Solution Growth of Modified Ultrathin W18O49 Nanobelts with Enhanced Chemical Activity against Alkylamine Radicals

Group IVB ions (Ti⁴⁺ and Zr⁴⁺) are employed to modify solution growth of W₁₈O₄₉ nanocrystals. In the presence of group IVB ions, the morphology of the produced monoclinic W₁₈O₄₉ nanocrystals can be modulated from inhomogeneous shapes to uniform an ultrathin nanobelt with the ( 01) lattice plane being the main exposure surface. Interestingly, the ultrathin W₁₈O₄₉ nanobelts exhibit a unique chemical activity against alkylamine radicals, probably originated from the highly increased exposure of the ( 01) plane with extra tungsten and oxygen atoms inserted in the regular lattice, which makes this nanomaterial an active photocatalyst for the N‐de‐ethylation reaction of the rhodamine B molecules, as well as a promising gas sensor matrix with selective responses to alkylamine molecules, including diethylamine, dimethylamine, triethylamine and trimethylamine. These results could provide useful inspiration for developing other functional nanomaterials with technical significance via modification of their morphologies and chemical properties.     

石墨相氮化碳/三聚氯氰复合光催化剂的制备及其光催化活性

研制了一种石墨相氮化碳/三聚氯氰(g-C₃N₄/C₃Cl₃N₃)复合型光催化剂。 由于该催化剂在g-C₃N₄的基础上有效拓展了π共轭体系,同时引入氯原子,使带隙位置上移,改善了光生电荷的还原能力,在可见光照射下,能有效降解有机污染物。 实验结果表明,20 min内对RR染料废水的降解率达94.7%,重复使用5次后,降解率仍达94%。 通过在降解体系中加入氧化性活性物种捕获剂的方法,研究了g-C₃N₄/C₃Cl₃N₃吸收可见光降解有机污染物的机理。     

SnO2纳米带的水辅助生长与表征

以高纯Sn粉为原料，采用水辅助生长法在850 ℃下合成了SnO₂纳米带，用SEM、TEM、XRD、EDX、 HRTEM和SAED对其形貌、结构和成份进行了表征，对SnO₂纳米带的光致发光和红外谱图进行了分析，探讨了水辅助生长SnO₂ 纳米带的化学原理和生长机制。结果表明：用水辅助生长法制备的SnO₂纳米带产量高、结构均匀，XRD衍射图与SnO₂的标准图完全一致，纳米带的宽度为70～100 nm，厚度为5～8 nm,长度可达数十微米；SnO₂纳米带光致发光在617 nm和651 nm处有2个强峰，在446 nm处有一个弱峰，这些都是由氧空位引起的；SnO₂纳米带的红外谱图中560.6 cm^-1处的峰属于表面振动模式；水辅助生长SnO₂纳米带的可能机制是VS生长机制。     

Growth and Characterization of [001] ZnO Nanorod Array on ITO Substrate with Electric Field Assisted Nucleation

This paper reports direct growth of [001] ZnO nanorod arrays on ITO substrate from aqueous solution with electric field assisted nucleation, followed with thermal annealing. X-ray diffraction analyses revealed that nanorods have wurtzite crystal structure. The diameter of ZnO nanorods was 60–300 nm and the length was up to 2.5 μm depending on the growth condition. Photoluminescence spectra showed a broad emission band spreading from 500 to 870 nm, which suggests that ZnO nanorods have a high density of oxygen interstitials. Low and nonlinear electrical conductivity of ZnO nanorod array was observed, which was ascribed to non-ohmic contact between top electrode and ZnO nanorods and the low concentration of oxygen vacancies.     

硼酸铝纳米棒的制备、结构及生长机理

以仲丁醇铝和硼酸为原料, 葡萄糖作模板剂, 在水介质中120 ℃形成淡黄色干凝胶, 再于750 ℃焙烧得到尺寸均一的硼酸铝纳米棒. 通过改变仲丁醇铝/硼酸的摩尔比实现了对产物形貌及长径比的控制合成. 采用X射线衍射(XRD)、扫描电镜(SEM)、透射电镜(TEM)对产物结构和形貌进行表征. 结果表明产物为Al4B2O9纳米棒, 直径为15-45 nm, 长度为100-300 nm. 根据表征结果对葡萄糖参与的硼酸铝纳米棒的生长机理进行了探讨. 结果表明, 葡萄糖与硼酸反应产生网状结构的配合物, 同时释放质子, 促使铝源均匀地分散在网格间, 为硼酸铝的生成提供一有利的反应空间. 纳米棒的生长为自催化生长过程, 在750 ℃热处理时沿着(100)面方向生长.     

新铌酸盐Sr5LnTi3Nb7O30的结构与介电性能

在SrO-Ln2O3-TiO2-Nb2O5(Ln=La, Y)体系中,通过固相反应法，合成了填满型钨青铜结构新铌酸盐Sr5LaTi3Nb7O30与Sr5YTi3Nb7O30.分别采用X射线衍射分析、扫描电镜进行了结构分析,并进行了介电性能测试.结果表明, Sr5LaTi3Nb7O30室温时为四方钨青铜结构顺电相,晶胞参数a=1.233 60(4) nm, c=0.388 01(2) nm;频率为1 MHz时,其陶瓷的室温相对介电常数为466,介电损耗约为5×10－3.Sr5YTi3Nb7O30为弛豫性铁电体, 10 kHz时居里温度为260 ℃;室温时为四方钨青铜结构铁电相,晶胞参数a=1.228 80(4) nm, c=0.387 05(2) nm; 1 MHz时,陶瓷体的室温相对介电常数为290.     

类钙钛矿新铌酸盐Ba5LaTi2Nb3O18的合成、结构与介电特性

为满足现代通信技术小型化、集成化与高可靠性的迫切要求,探索具有高介电常数、低介电损耗与低温度系数的微波介电材料引起了材料科学、化学、物理和电子科学等领域科学工作者的广泛关注,并已开发出复合钙钛矿结构的Ba(Mg1/3Ta2/3)O3、Ba(Zn1/3Ta2/3)O3和钨青铜结构的Ba6-3xLn8+2x·Ti18O54及Ba2Ti9O20等实用化的高性能材料[1～7].这类材料均由氧八面体共顶连接,而且氧八面体内(B位)、外(A位)阳离子比例等于或略大于1,由此,我们推测在B位与A位阳离子比例略小于1的类钙钛矿结构中也极有可能存在具有优良介电性能的新材料,因此对通式为AnBn-1O3n(n=5,6,7,8)的系列新化合物进行了系统的合成、结构与介电性能研究[8,9].本文报道在BaO-La2O3-TiO2-Nb2O5体系中合成的具有5层类钙钛矿结构的新铌酸盐Ba5LaTi2Nb3O18,发现该材料具有较好的介电性能.     

Boron Nitride Nanosheets Improve Sensitivity and Reusability of Surface‐Enhanced Raman Spectroscopy

Surface enhanced Raman spectroscopy (SERS) is a useful multidisciplinary analytic technique. However, it is still a challenge to produce SERS substrates that are highly sensitive, reproducible, stable, reusable, and scalable. Herein, we demonstrate that atomically thin boron nitride (BN) nanosheets have many unique and desirable properties to help solve this challenge. The synergic effect of the atomic thickness, high flexibility, stronger surface adsorption capability, electrical insulation, impermeability, high thermal and chemical stability of BN nanosheets can increase the Raman sensitivity by up to two orders, and in the meantime attain long‐term stability and extraordinary reusability not achievable by other materials. These advances will greatly facilitate the wider use of SERS in many fields.     

石墨相氮化碳量子点的简易水热制备和荧光性能

本文以线状石墨相氮化碳(Lg-CN)为原料,在无需强酸加入的情况下,利用简单的纯水中的水热反应成功制得了氮化碳量子点(CN QDs),并利用傅里叶变换红外光谱、X射线粉末衍射、透射电镜、X射线光电子能谱等对所得量子点的形貌和结构进行了表征,进而解释了量子点的形成机理;利用紫外-可见吸收光谱和荧光光谱对其光学性质进行了研...     

类钙钛矿新铌酸盐Ba3La2Ti2Nb2O15的合成、结构与介电特性

为满足现代通信技术的小型化、集成化与高可靠性的迫切要求,探索具有高介电常数、低介电损耗与低温度系数的微波介电材料引起了材料科学、化学、物理和电子学等领域科学工作者的广泛关注,并已开发出复合钙钛矿结构[Ba(Zn1/3Ta2/3)O3]和钨青铜结构[Ba6-3xLn8+2xTi18O54]等实用化的高性.     

聚异丙胺基环硼氮烷裂解制备氮化硼及其抗氧化与介电性能

以异丙胺和三氯环硼氮烷(TCB)为原料,在较温和条件下合成了一种可溶可熔的聚异丙胺基环硼氮烷(PTPiAB),后经高温裂解制得六方氮化硼(h-BN).利用元素分析、TGA、FTIR、XRD和网络分析仪等对先驱体及裂解产物的组成、结构和性能进行了表征.结果表明,PTPiAB的结构中含有B3N3六元环,N-H、C-H和C-N键,其熔点约70 oC.1000 oC时在NH3和Ar中的陶瓷产率分别为45.9 %和52.8 %.NH3中裂解失重主要发生在800 oC以下,1000 oC左右开始结晶,1800 oC时得到BN的(002)晶面间距为0.334 nm,密度为2.03 g·cm-3.该BN表现出了较好的高温抗氧化性能,在空气中900 oC以下增重小于0.3%.此外,室温下测试频率为10 GHz时的介电常数实部和损耗角正切分别为2.48和0.03.