超细Pd纳米线表层富Pt作为耐久性氧还原催化剂研究

本文控制合成一维方向生长的直径为1.5 nm,长度为11.8 nm的超细Pd纳米线,结合欠电位沉积方法在其表面制备了不同Pt原子层的Pd@Pt核壳结构纳米电催化剂. 高分辨透射电镜和光电子能谱结果证实了这种核壳结构及Pt在Pd纳米线上的均匀分布. 相比于商业化Pt黑催化剂,该核壳结构电催化剂对酸性介质中的氧气还原反应呈现了较高的电催化活性和增强的耐久性. 显著增强的耐久性可归属于催化剂一维结构的稳定性.     

Enhanced electrocatalytic performance of processed, ultrathin, supported Pd-Pt core-shell nanowire catalysts for the oxygen reduction reaction

We report on the synthesis, characterization, and electrochemical performance of novel, ultrathin Pt monolayer shell-Pd nanowire core catalysts. Initially, ultrathin Pd nanowires with diameters of 2.0 ± 0.5 nm were generated, and a method has been developed to achieve highly uniform distributions of these catalysts onto the Vulcan XC-72 carbon support. As-prepared wires are activated by the use of two distinctive treatment protocols followed by selective CO adsorption in order to selectively remove undesirable organic residues. Subsequently, the desired nanowire core-Pt monolayer shell motif was reliably achieved by Cu underpotential deposition followed by galvanic displacement of the Cu adatoms. The surface area and mass activity of the acid and ozone-treated nanowires were assessed, and the ozone-treated nanowires were found to maintain outstanding area and mass specific activities of 0.77 mA/cm(2) and 1.83 A/mg(Pt), respectively, which were significantly enhanced as compared with conventional commercial Pt nanoparticles, core-shell nanoparticles, and acid-treated nanowires. The ozone-treated nanowires also maintained excellent electrochemical durability under accelerated half-cell testing, and it was found that the area-specific activity increased by ~1.5 fold after a simulated catalyst lifetime.     

Effect of H2 on the electrical transport properties of single Bi2S3 nanowires

Field effect transistors have been fabricated using Bi2S3 nanowires. Whether the contact is ohmic or non-ohmic, the current of Bi2S3 nanowires was found to increase remarkably in H2 compared to that in a vacuum. Carrier density and mobility within the nanowires and the contact barriers between the nanowires and the electrodes have been extracted using field effect and two-probe current-voltage curves. It was found that H2 enhances electronic mobility and carrier density within the nanowires dramatically. The effect of H2 on the contact barriers was observed to be negligible compared to the other two effects.     

Copper-based nanowire materials: templated syntheses, characterizations, and applications

Well-aligned Cu(OH)2 nanoribbon and CuO nanorod arrays have been prepared on copper substrates by liquid-solid reactions. The effects of temperature, reaction time, solvent, and pH value on the morphology and composition of the products are systematically studied. Using the Cu(OH)2 nanoribbons array as a reactive and sacrificial template, we have successfully synthesized Cu2O, Cu9S8, and Cu nanoribbon/ nanowire arrays, demonstrating the versatility of the template. The extensive series of copper-based one-dimensional nanomaterials have been fully characterized by various structural, microscopic, and spectroscopic techniques. Moreover, the Cu nanowires are demonstrated to be an excellent surface-enhanced Raman scattering substrate with a sensitivity over an order of magnitude higher than that of a common roughened copper electrode.     

Molecular Template Assisted Growth of Ultrathin Silicon Carbide Nanowires with Strong Green Light Emission and Excellent Field‐Emission Properties

A novel molecule template assisted chemical co‐reduction method has been successfully developed for the controlled synthesis of ultrathin β‐SiC single‐crystalline nanowires on a large scale. The ultrathin β‐SiC single‐crystalline nanowires are about 8 nm in diameter and 200–800 nm in length. The resulting thin β‐SiC single‐crystalline nanowire is new in the family of β‐SiC one‐dimensional (1D) nanostructures. A synergistic action of π‐stacking and steric hindrance result from the 1,10‐phenanthroline molecule template are proposed to explain the growth mechanism of the ultrathin β‐SiC single‐crystalline nanowires based on the experimental observation. Importantly, such ultrathin β‐SiC nanowire has shown a strong structure‐induced enhancement of photoluminescence properties and has exhibited a very strong green light emission, which can be seen by naked eye. Furthermore, the unique β‐SiC ultrathin nanowire structure exhibits a low turn‐on field (3.57 V μm^?1) and a large field‐emission current density (20 mA cm^?2). These results suggest that the ultrathin β‐SiC nanowires can be expected to find promising applications as field emitters and photoelectronic devices.     

The role of oxidative etching in the synthesis of ultrathin single-crystalline Au nanowires

The fabrication of ultrathin single-crystal Au nanowires with high aspect ratio and that are stable in air is challenging. Recently, a simple wet-chemical approach using oleylamine has been reported for the synthesis of Au nanowires with micrometer length and 2 nm in diameter. Despite efforts to understand the mechanism of the reaction, an ultimate question about the role of oxygen (O(2)) during the synthesis remained unclear. Here we report that the synthesis of ultrathin Au nanowires employing oleylamine is strongly affected by the amount of O(2) absorbed in the reaction solution. Saturating the solution with O(2) leads to both a high-yield production of nanowires and an increase in their length. Nanowires with diameters of about 2 nm and lengths of 8 μm, which corresponds to an aspect ratio of approximately 4000, were produced. The role of oxygen is attributed to the enhanced oxidation of twin defects on Au nanoparticles formed in the first stage of the reaction. Understanding the role of oxidative etching is crucial to significantly increasing the yield and the length of ultrathin Au nanowires.     

Large‐Area Alignment of Tungsten Oxide Nanowires over Flat and Patterned Substrates for Room‐Temperature Gas Sensing

Alignment of nanowires over a large area of flat and patterned substrates is a prerequisite to use their collective properties in devices such as gas sensors. In this work, uniform single‐crystalline ultrathin W₁₈O₄₉ nanowires with diameters less than 2 nm and aspect ratios larger than 100 have been synthesized, and, despite their flexibility, assembled into thin films with high orientational order over a macroscopic area by the Langmuir–Blodgett technique. Alignment of the tungsten oxide nanowires was also possible on top of sensor substrates equipped with electrodes. Such sensor devices were found to exhibit outstanding sensitivity to H₂ at room temperature.     

Template- and surfactant-free synthesis of ultrathin CeO2 nanowires in a mixed solvent and their superior adsorption capability for water treatment

Ultrathin CeO₂ nanowires with a diameter of 5 nm and an aspect ratio of more than 100 can be prepared by a one-step refluxing approach in a mixed solvent composed of water and ethanol without using any templates or surfactants. The formation mechanism of the as-synthesized ultrathin nanowires has been investigated. The as-synthesized CeO₂ nanowires with a high surface area of 125.31 m² g^–1 exhibited excellent wastewater treatment performance with high removal capacities towards organic dyes and heavy metal ions. In addition, the as-synthesized CeO₂ nanowires can adsorb Congo red selectively from a mixed solution composed of several dyes. Successful access to high quality ultrathin nanowires will make it possible for their potential application in catalysis and other fields.     

Facile Synthesis of Ultrathin Bimetallic PtSn Wavy Nanowires by Nanoparticle Attachment as Enhanced Hydrogenation Catalysts

Ultrathin wavy nanowires represent an emerging class of nanostructures that exhibit unique catalytic, magnetic, and electronic properties, but the controlled production of bimetallic wavy nanowires remains a significant challenge. Ultrathin bimetallic PtSn nanowires have been prepared with high yield and featuring a highly wavy structure. Owing to the ultrathin nature and unique electronic properties of these PtSn wavy nanowires, they exhibit improved catalytic performance for the hydrogenation of nitrobenzene, as well as for the hydrogenation of styrene. These results suggest a new strategy to prepare highly active catalysts through defect engineering and can significantly impact broad practical applications.     

Synthesis of uniform Cu2S nanowires from copper-thiolate polymer precursors by a solventless thermolytic method

Uniform hexagonal Cu2S nanowires with 2-6 nm diameters, 0.1 to several mum in length, were made by precipitation and thermolysis at 155 degrees C for 120 min from a Cu-thiolate colloid with a viscosity of 93.5 mPa/s. The morphologies of the final nanoproducts are governable through control of the coordination chemistry of Cu ions and thiols and the association of the Cu/S fragments. The evolution of nanowires, with the polymerization and heating temperature, and the parameters affecting the viscosity of the colloid precursor are reported.     

基于AuCl(油胺)复合物合成形貌可控的金纳米结构

简要综述了使用一价金复合物AuCl(油胺)作为前驱物合成形貌可控的金纳米结构的相关工作. 通过改变有机溶剂、添加异质金属纳米粒子及控制反应温度等手段, 成功合成出球形的金纳米粒子(平均直径12.7 nm)、超细金纳米线(平均直径1.8 nm)及超细金纳米棒(平均直径2 nm); 并通过牺牲磁性纳米粒子模板的方法合成出枝状金纳米结构. 除了对合成方法和过程的介绍, 还简要讨论了每种纳米结构的形成机制.     

An improved sensitivity non-enzymatic glucose sensor based on a CuO nanowire modified Cu electrode

CuO nanowires have been prepared and applied for the fabrication of glucose sensors with highly enhanced sensitivity. Cu(OH)(2) nanowires were initially synthesised by a simple and fast procedure, CuO nanowires were then formed simply by removing the water through heat treatment. The structures and morphologies of Cu(OH)(2) and CuO nanowires were characterised by X-ray diffraction, X-ray photoelectron spectroscopy, scanning electron microscopy, and transmission electron microscopy. The direct electrocatalytic oxidation of glucose in alkaline medium at CuO nanowire modified electrodes has been investigated in detail. Compared to a bare Cu electrode, a substantial decrease in the overvoltage of the glucose oxidation was observed at the CuO nanowire electrodes with oxidation starting at ca. 0.10 V vs. Ag/AgCl (saturated KCl). At an applied potential of 0.33 V, CuO nanowire electrodes produce high and reproducible sensitivity to glucose with 0.49 microA/micromol dm(-3). Linear responses were obtained over a concentration range from 0.40 micromol dm(-3) to 2.0 mmol dm(-3) with a detection limit of 49 nmol dm(-3) (S/N = 3). The CuO nanowire modified electrode allows highly sensitive, low working potential, stable, and fast amperometric sensing of glucose, thus is promising for the future development of non-enzymatic glucose sensors.     

表面悬挂键对GaAs纳米线掺杂的影响及其钝化

利用第一性原理计算方法研究了表面悬挂键对GaAs纳米线掺杂的影响及其钝化．计算结果显示,不论是闪锌矿结构还是纤锌矿结构,GaAs纳米线表面Ga原子上带正电荷的表面悬挂键都是一类稳定的缺陷,并且这种稳定性不会随着纳米线直径的变化而变化．这种表面悬挂键会形成载流子陷阱中心从而从p型掺杂的GaAs纳米线俘获空穴,使得纳米线的掺杂效率下降．和NH3相比,NO2 具有足够的电负性来俘获GaAs纳米线表面悬挂键上的未配对电子,从而有效地钝化GaAs纳米线的表面悬挂键,提高纳米线的p型掺杂效率,并且这种钝化特性不会随着纳米线直径的变化而改变．     

Ultrathin ZnS single crystal nanowires: controlled synthesis and room-temperature ferromagnetism properties

Highly uniform single crystal ultrathin ZnS nanowires (NWs) with 2 nm diameter and up to 10 μm length were fabricated using a catalyst-free colloidal chemistry strategy. The nanowires crystallized in hexagonal phase structure with preferential growth along the direction of the (001) basal plane. The strong polarity of the (001) plane composed of Zn cations or S anions drives the oriented attachment of ZnS nanocrystals (NCs) along this direction via electrostatic (or dipole) interaction. The ultrathin ZnS nanowires show intrinsic ferromagnetism at room temperature and other unusual properties related to its unique nature, such as large anisotropic lattice expansion, large blue-shift of UV-vis absorption band of the excition, and photoluminescence spectrum of the exciton band edge. First-principles DFT computation results show that Zn vacancies can induce intrinsic ferromagnetism in these undoped ZnS NWs. The main source of the magnetic moment arises from the unpaired 3p electrons at S sites surrounding the Zn vacancies carrying the magnetic moment ranging from 0.26 to 0.66 μ(B). Calculated results indicate that the magnetic moment of the ultrathin ZnS NWs can be increased by increasing the Zn vacancy concentration without significant energy cost. The calculated magnetization value (1.96 or 0.40 emu/g for Zn vacancies on the surface of NWs or inside, respectively) by Zn(53)S(54) supercell model is larger than our experimental value (0.12 emu/g at 1.8 K and 0.05 emu/g at 300 K), but the ferromagnetic result is qualitatively in agreement.     

Highly efficient synthesis of N-substituted isoindolinones and phthalazinones using Pt nanowires as catalysts

A series of N-substituted isoindolinones have been successfully synthesized through the reductive C-N coupling and intramolecular amidation of 2-carboxybenzaldehyde and amines. This one-pot synthesis gives excellent yields using ultrathin Pt nanowires as catalysts under 1 bar of hydrogen. These unsupported catalysts can also be used for the synthesis of phthalazinones in high yield when hydrazine or phenyl hydrazine is used instead of amines.     

A novel synthesis of ultrathin CoPt3 nanowires by dealloying larger diameter Co99Pt1 nanowires and subsequent stress-induced crack propagation

A novel approach to the fabrication of ultrathin CoPt₃ nanowires with a diameter of a few nanometers has been developed, by taking advantage of the volume shrinkage and formation of nanoporous structures upon dealloying electrodeposited Co₉₉Pt₁ nanowires (28 nm in diameter), followed by an ultrasonication treatment. The as-produced ultrathin CoPt₃ nanowires have an average diameter of 5 nm and lengths of up to 10 μm, and are found to be ferromagnetic at room temperature.     

A universal strategy for fast,scalable, and aqueous synthesis of multicomponent palladium alloy ultrathin nanowires

Noble metal alloy nanowires(NWs)with ultrathin diameters(2–3 nm)and precisely controllable elemental compositions have attracted dramatically growing attention for(electro)catalysis.Despites numerous achievements in past two decades,noble metal alloy NWs are mostly synthesized with the traditional oil-phase methods that suffer from some undesirable drawbacks.Here,we report a general strategy for fast,scalable,and aqueous synthesis of multicomponent Pd-based alloy ultrathin NWs with an average diameter of 2.6 nm,ranging from bimetallic PdM(PdFe,PdCo,PdNi,PdCu,PdZn,PdRu,PdRh,PdAg,PdCd,PdIr,PdPt,PdAu)and binary PdS/PdP NWs,to trimetallic PdM1M2 NWs(PdAuCu,PdCoNi,PdCuZn,PdCuNi,PdAgCu,PdAuCu,PdRuAg,PdAuRu,and PdPtAu),and to tetrametallic PdM1M2M3 NWs(PdAuAgCu,PdCoCuNi,PdAuCuNi,PdPtAuCu,and PdIrPtAu).The key to the success of this aqueous synthesis is the utilization of N2H4 as the extremely strong reducing agent that directs the synchronous reduction and anisotropic nucleation growth of multicomponent Pd alloy NWs along nanoconfined columnar phase assembled with amphiphilic dioctadecyldimethylammonium chloride.As-resultant Pd-based alloy ultrathin NWs exhibit multiple structural and compositional synergies,which remarkably optimize the removal of poisoning ethoxy intermediates and thus improve electrocatalytic performance towards ethanol oxidation reaction(EOR).Among them,tetrametallic PdAuCuNi alloy ultrathin NWs hold a high EOR activity of 5.14 A mg-1 Pd and a low activation energy of 13.1 kJ mol^-1,both of which are much better than its counterpart catalysts alloyed with less elements.This work represents an important advance in precise aqueous synthesis of multicomponent noble metal alloy ultrathin NWs as the high-performance electrocatalysts for various targeted applications.     

First-Principles Study of Ultrathin Molybdenum Sul des Nanowires: Electronic and Catalytic Hydrogen Evolution Properties

Molybdenum sulfides nanomaterials, such as one-dimensional (1D) nanotubes, nanoribbons, and two-dimensional (2D) nanosheets, have attracted intensive research interests for their novel electronic, optical, and catalytic properties. On the basis of first-principles calculation, here, we report a new series of 1D ultrathin molybdenum sulfides nanowires, including Mo₂S₆、Mo₃S₆ and Mo₆S₁₀ nanowires. Our results demonstrate that these ultrathin nanowires are both thermal and lattices dynamically stable, confirmed with the calculated phonon spectrum and Born-Oppenheimer molecular dynamic simulation at the temperature up to 600 K. The calculated elastic constant is 21.33, 103.22, and 163.00 eV/? for Mo₂S₆, Mo₃S₆, and Mo₆S₁₀ nanowires, respectively. Mo₂S₆ and Mo₃S₆ nanowires are semiconductors with band gap of 1.55 and 0.46 eV, while Mo₆S₁₀ nanowires is metal, implying their potential applications in electronics and optoelectronics. In particular, ultrathin molybdenum sulfides nanowires can be used as catalysts for hydrogen evolution reaction. The calculated Gibbs free energy change for hydrogen evolution is about -0.05 eV for Mo₂S₆ nanowire, comparable with those of Pt and H-MoS₂. The prediction of these 1D molybdenum sulfides nanowires may enrich the 1D family molybdenum sulfides and make a supplement to understand the high performance of hydrogen evolution reaction in transition-metal dichalcogenides.     

Fabrication of Cu(OH)<Subscript>2</Subscript> Nanowires Blended Poly(vinylidene fluoride) Ultrafiltration Membranes for Oil-Water Separation

Cu(OH)2 nanowires were prepared and incorporated into poly(vinylidene fluoride) (PVDF) to fabricate Cu(OH)2-PVDF ultrafiltration (UF) membrane via immersion precipitation phase inversion process.The effect of Cu(OH)2 nanowires on the morphology of membranes was investigated by X-ray photoelectron spectroscopy (XPS),Fourier transform infrared (FTIR) spectroscopy,atomic force microscopy (AFM),scanning electron microscopy (SEM) and X-ray diffraction (XRD) measurements.The results showed that all the Cu(OH)2-PVDF membranes had wider fingerlike pore structure and better hydrophilicity,smoother surface than pristine PVDF membrane due to the incorporation of Cu(OH)2 nanowires.In addition,water flux and bovine serum albumin (BSA) rejection were also measured to investigate the filtration performance of membranes.The results indicated that all the Cu(OH)2-PVDF membranes had high water flux,outstanding BSA rejection and excellent antifouling properties.It is worth mentioning that the optimized performance could be obtained when the Cu(OH)2 nanowires content reached 1.2 wt％.Furthermore,the membrane with 1.2 wt％ Cu(OH)2 nanowires showed outstanding oil-water emulsion separation capability.     

POM-Incorporated CoO Nanowires for Enhanced Photocatalytic Syngas Production from CO2

Utilizing sustainable energy for chemical activation of small molecules, such as CO₂, to produce important chemical feedstocks is highly desirable. The simultaneous production of CO/H₂ mixture (syngas) from photoreduction of CO₂ and H₂O is highly promising. However, the relationships between structure, composition, crystallinity, and photocatalytic performance are still indistinct. Here, amorphous ultrathin CoO nanowires and polyoxometalate incorporated nanowires with even lower crystallinity were synthesized. The POM-incorporated ultrathin nanowires exhibit high photocatalytic syngas production activity, reaching H₂ and CO evolution rates of 11555 and 4165 μmol g⁻¹ h⁻¹ respectively. Further experiments indicate that the ultrathin morphology and incorporation of POM both contribute to the superior performance. Multiple characterizations reveal the enhanced charge–hole separation efficiency of the catalyst would facilitate the photocatalysis.