Effect of Molar Ratio of Citric Acid to Metal Nitrate on the Structure and Catalytic Activity of NiO Nanoparticles

NiO nanoparticles were prepared by means of sol-gel method via varying the ratio of citric acid to nickel nitrate. The samples were characterized by powder X-ray diffraction(XRD), Fourier transform infrared(FTIR) spectroscopy, transmission electron microscopy(TEM) and X-ray photoelectron spectroscopy(XPS). It was found that the molar ratio of citric acid to nickel nitrate has a great effect on the crystal structure and particle size of NiO. The increase of the molar ratio of citric acid to nickel nitrate is favorable to the formation of NiO smaller particles within the range tested. Compared to bulk NiO obtained by thermal decomposition, NiO nanoparticles possess more surface oxygen species O^-. The activity test indicates that surface oxygen species O^- plays a crucial role in the hydroxylation of benzene to phenol with hydrogen peroxide as oxidant. The active site may be originated from Ni²⁺ on the surface of the samples, while Ni⁰ does not contribute to the hydroxylation reaction.     

拓扑绝缘体二维纳米结构与器件

拓扑绝缘体是一种全新的量子功能材料, 具有绝缘性体能带结构和受时间反演对称性保护的自旋分辨的金属表面态, 属于Dirac 粒子系统, 将在新原理纳电子器件、自旋器件、量子计算、表面催化和清洁能源等方面有广泛的应用前景. 理论和实验相继证实Sb₂Te₃, Bi₂Se₃和Bi₂Te₃单晶具有较大的体能隙和单一Dirac 锥表面态, 已经迅速成为了拓扑绝缘体研究中的热点材料. 然而, 利用传统的高温烧结法所制成的拓扑绝缘体单晶块体样品常存在大量本征缺陷并被严重掺杂, 拓扑表面态的新奇性质很容易被体载流子掩盖. 拓扑绝缘体二维纳米结构具有超高比表面积和能带结构的可调控性, 能显著降低体态载流子的比例和凸显拓扑表面态, 并易于制备高结晶质量的单晶样品, 各种低维异质结构以及平面器件. 近年来, 我们一直致力于发展拓扑绝缘体二维纳米结构的控制生长方法和物性研究. 我们发展了拓扑绝缘体二维纳米结构的范德华外延方法, 实现了高质量大比表面积的拓扑绝缘体二维纳米结构的可控制备, 并实现了定点与定向的表面生长. 开展拓扑绝缘体二维纳米结构的谱学研究, 利用角分辨光电子能谱直接观察到拓扑绝缘体狄拉克锥形的表面电子能带结构, 发现了拉曼强度与位移随层数的依赖关系. 设计并构建拓扑绝缘体纳米结构器件, 系统研究其新奇物性, 观测到拓扑绝缘体Bi₂Se₃表面态的Aharonov-Bohm (AB)量子干涉效应等新奇量子现象, 通过栅电压实现了拓扑绝缘体纳米薄片化学势的调控, 并将拓扑绝缘体纳米结构应用于柔性透明导电薄膜. 本文首先简单介绍拓扑绝缘体的发展现状, 然后系统介绍我们开展的拓扑绝缘体二维纳米结构的范德华外延生长、谱学、电学输运特性以及透明柔性导电薄膜应用的研究, 最后对该领域所面临的机遇和挑战进行简要的展望.     

不同形貌ZnO纳米结构的电子显微分析

控制实验合成条件,利用溶胶-凝胶法和化学溶液生长法制备出不同形貌的ZnO纳米结构。采用X射线衍射仪(XRD)、扫描电子显微镜( SEM) 以及透射电子显微镜(TEM)等多种测试手段对ZnO纳米结构的微观形态及晶相进行了分析。结果表明:3种ZnO纳米结构形貌虽不同,但均具有Z nO六方纤锌矿晶相结构。ZnO纳米棒和花状ZnO纳米结构为单晶,生长方向均沿(0001)方向。ZnO纳米球则为多晶。     

Large 1,3,5-triazine-based ligands coordinating transition metal ions: syntheses and structures of the ligands and the ball shaped nanometer-scaled Co complex [Co(2,4-R-6-R′-1,3,5-triazine)2](Br1.7(OH)0.3) · 4.8H2O {R = bis(2-diphenylmethylene) hydrazinyl; R′ = piperidin-1-yl}

Two new, large 1,3,5-triazine-based ligands with only N-donor functions were synthesized as well as the Co(II) salt [Co(DHPTBenz)₂](Br_1.7(OH)_0.3) · 4.8H₂O (DHPTBenz = 2,4-bis-(2-diphenylmethylene)-hydrazinyl-6-piperidin-1-yl-1,3,5-triazine). Single crystal X-ray structures of the Co(II) complex, DHPTBenz, and 2,4-dichloro-6-(piperidin-1-yl)-1,3,5-triazine (DCPT) have been determined. The last compound was used as starting material for the tridentate DHPTBenz ligand. Spectroscopic data of the ligand and the starting materials are reported. The Co(II) ion in the complex is distorted octahedrally coordinated by six N atoms of two DHPTBenz ligands. One N atom of the triazine ring of each ligand bonds axially with short distances of 1.953(3) Å and 1.954(3) Å, respectively, whereas two of the hydrazine-N atoms of two ligands form the equatorial plane with an average Co–N bond distance of 2.313 Å. The complex cation has a slightly elongated, nanometer-scaled ball shape with the longest diameter of 1.82 nm.     

手性纳米材料:生物成像、生物传感与治疗

手性无机纳米结构不仅形貌和结构可调控、 易于表面功能化修饰, 而且光学性质独特, 在生物领域的应用上展现了很大的优异性. 本文综述了近年来手性纳米技术在生物医学领域的研究进展, 重点介绍了手性金属和手性半导体纳米结构的合成策略、 圆二色效应、 光手性机制及在生物成像、 生物传感、 肿瘤以及神经退行性疾病等医学领域的应用. 手性纳米材料的研究丰富了生物化学的纳米技术手段, 促进了肿瘤等重大疾病诊断与治疗技术的进步, 推动了手性在生命科学中的发展, 鼓励了研究者对这一新兴领域的持续探索与挑战.     

Synthetic strategy of dendrimers: A review

Dendrimer chemistry is a fascinating and growing area of modern chemistry. Dendrimers are macromolecular entities with unique three-dimensional topologies, multi-functionality, and unique chemical and physical properties. Because of these characteristics, they are particularly well suited for applications in nanotechnology, pharmaceuticals, and medicinal chemistry. The study of dendrimers and hyperbranched polymers is gaining widespread interest from researchers in academia and industry for their unique structure and properties. This review article focused on dendrimer structure and the different synthetic strategies employed at the laboratory and commercial levels. This review covers convergent and divergent approaches, as well as accelerated approaches to dendrimer synthesis.     

Influence of synthesis and operating parameters on silicalite-1 membrane properties

The present study deals with the synthesis of nanostructured silicalite-1 membranes on porous α-Al₂O₃ supports by a hydrothermal method. Different parameters including the synthesis conditions (temperature and alkalinity) and operating conditions (temperature and pressure) were investigated. The membranes were characterized by X-ray diffraction and scanning electron microscopy techniques. The optimum synthesis temperature and alkalinity were determined to be 160 °C and pH = 11, respectively. The permeability of CO₂ and CH₄ through the optimized membrane was determined by the pressure drop method. The results revealed that the main effective separation mechanism was adsorption. The permeation of CO₂ and CH₄ declined with increasing temperature, whereas high feed pressures enhanced the single gas flux. The CO₂ and CH₄ permeability values at 30 °C and 2 bar were 1.62 × 10^?7 and 2.07 × 10^?7 mol m^?2 s^?1 Pa^?1, respectively. Furthermore, the response surface methodology analysis confirmed the significance of all the variables and the proposed model. Excellent correlation between the experimental and predicted data (R² = 0.99) was obtained, confirming that response surface methodology is a powerful tool for modeling nanostructured silicalite-1 membrane processes.     

Synthesis and characterization of nanostructure hydrous iron–titanium binary mixed oxide for arsenic sorption

Synthesis of nanostructure hydrous iron–titanium binary mixed oxide (NHITBMO) had been reported by a simple method, and characterized by the X-ray diffraction (XRD), thermal analysis, transmission electron microscope (TEM), Föurier Transform Infrared (FTIR), surface area, and zero surface charge pH (pHzpc). The synthetic oxide was hydrated and microcrystalline with 77.8 m² g^?1 BET surface area. The particle size (nm) calculated using XRD peak table and TEM image was ~10–13 and 6–8, respectively. The pH_zpc value was 6.0 (±0.05) for the oxide. The NHITBMO showed pH dependent good sorption affinity for arsenic from the aqueous solution and, the Langmuir monolayer capacity (mg g^?1) was 80.0 and 14.6, respectively, for the As(III) and As(V). The pseudo-second order equation described the room temperature arsenic sorption kinetic data well. The minimum dose required was 1.6 g NHITBMO per L of water (As_total = 0.24 mg L^?1) to reduce the arsenic level below 0.01 mg L^?1 in batch treatment process.     

Effect of N2 ion flux on the photocatalysis of nitrogen-doped titanium oxide films by electron-beam evaporation

Nitrogen-doped titanium oxide (TiO_xN_y) films were prepared with ion-assisted electron-beam evaporation. The nitrogen (N) incorporated in the film is influenced by the N₂ flux modulated by the N₂ flow rate through an ion gun. The TiO_xN_y films have the absorption edge of TiO₂ red-shifted to 500 nm and exhibit visible light-induced photocatalytic properties in the surface hydrophilicity and the degradation of methylene blue. The structures and states of nitrogen in the films are investigated by X-ray diffraction patterns (XRD), and X-ray photoelectron spectroscopy (XPS) and related to their visible light-induced photocatalytic properties. The results indicate that the substitutional N in anatase TiO₂ can induce visible light photocatalysis. The substitutional N is readily doped by the energetic nitrogen ions from the ion gun. The best photocatalytic activity is obtained at the largest N loading about 5.6 at.%, corresponding to the most substitutional N in anatase TiO₂. The film exhibits the degradation of methylene blue with a rate-constant (k) about 0.065 h⁻¹ and retaining 7° water contact angle on the surface under visible light illumination.     

Profile calculation of gold nanostructures by dispersed-nanosphere lithography through oblique etching for LSPR applications

Nanosphere lithography is an inexpensive method used to fabricate gold nanostructures on a substrate. Using dispersed-nanosphere lithography, in which the nanospheres are dispersed on a substrate, 2D or 3D nanostructures can be fabricated by obliquely depositing a gold film on the nanospheres and etching the gold film afterward. These nanostructures are tunable and acute, and are thus good emitting elements for the localized surface plasmon resonance applications. So far, for the fabrication of nanostructures on a substrate with dispersed nanospheres, only 2D nanostructures have been reported through perpendicular etching. We report in this paper that the 3D nanostructures fabricated by dispersed-nanosphere lithography are rigid non-conformal structures, and perpendicular gold etching can be expanded to oblique etching, which provides more possibilities for fabricating the gold nanostructures in various shapes. The profiles of gold nanostructures after several varying angle depositions, and their final profiles after perpendicular or oblique etching, are calculated in this paper. Our profile simulations are applicable for nanospheres (or microspheres) within the range of tens of nanometers to tens of micrometers, and are consistent with our fabricated nanostructures observed using scanning electron and atomic force microscopy. Electronic Supplementary Material  The online version of this article (doi:) contains supplementary material, which is available to authorized users.