Green synthesis and catalytic function of tungsten oxide nanoparticles

In this paper, a green chemical synthetic route was developed to synthesize WO3 nanoparticles with an average size of 70 nm. The products were characterized in detail by multiform techniques: X-ray diffraction (XRD), energy-dispersive X-ray analysis (EDS), scanning electron microscopy (SEM), and transmission electron microscopy (TEM). The photoluminescence of the obtained WO3 nanoparticles was also investigated. The effects of the hydrothermal temperature on the crystalline phase and morphology of the products have been studied systematically. The photocatalytic activity of the samples was evaluated by photocatalytic decolorization of methylene blue (MB) aqueous solution. The electrocatalytic activity was characterized using voltammetric techniques. The results showed that the obtained WO3 nanoparticles have an excellent photocatalytic and electrocatalytic performance for the MB.     

不使用保护气氛和还原剂超声制备纳米钯颗粒

在存在微量聚乙烯吡咯烷酮(PVP)、不用气氛保护和还原剂的条件下超声还原氯化钯水溶液,合成出单分散纳米金属钯粒子,用TEM、HRTEM、FT-IR、XRD等技术进行了表征.TEM、HRTEM观察表明纳米金属钯粒子表现出单分散性,为柱状晶体;纳米钯粒子在溶液中的稳定分散存在主要与FT IR揭示的PVP羰基基团与钯原子存在一定的配位吸附作用和PVP的长链空间位阻效应有关.     

A cost-effective preparation method of Ba-hexaaluminate nanoparticles for catalytic combustion of methane

The rod-like hexaaluminate nanoparticles have been prepared by using the alumina sol as the (NH₄)₂CO₃ co-precipitation precursor and supercritical drying (SCD) method. Formation of the final hexaaluminate likely occurs via diffusion of the Ba²⁺ ions into the δ-Al₂O₃ matrix. Only Ba-hexaaluminate phase (alumina-rich phase) is observed in the hexaaluminate products. Since the network of the aerogel has a higher stability than that formed by using aluminum nitrate, leading to the decrease in the mobility of aluminum at high calcination temperature, which plays a significant role in maintaining high surface area and pore structure.     

Collagen fiber with surface-grafted polyphenol as a novel support for Pd(0) nanoparticles: Synthesis,characterization and catalytic application

The aim of this study is to use collagen fiber (CF) as a natural polymeric support to synthesize a novel palladium (Pd) nanoparticle catalyst. To achieve a stable immobilization of Pd on CF support, epigallocatechin-3-gallate (EGCG), a typical plant polyphenol, was grafted onto CF surface, acting both as dispersing and stabilizing agent for Pd nanoparticles. Scanning electron microscopy showed that this catalyst was in ordered fibrous state with high flexibility. The presence of EGCG grafted on CF and the interaction mechanism of Pd ions with support was investigated by X-ray photoelectron spectroscopy. X-ray diffraction and transmission electron microscopy offered evidence that the well-dispersed Pd nanoparticles were generated on the outer surface of CF. By using the hydrogenation of allyl alcohol as a model reaction, the synthesized catalyst presented remarkably improved activity, selectivity and reusability as compared with the Pd catalyst supported by CF without grafting of EGCG.     

Functionalizing nanowires with catalytic nanoparticles for gas sensing application

Metal oxide semiconducting nanowires are among the most promising materials systems for use as conductometric gas sensors. These systems function by converting surface chemical processes, often catalytic processes, into observable conductance variations in the nanowire. The surface properties, and hence the sensing properties of these devices can be altered dramatically improving the sensitivity and selectivity, by the deposition of catalytic metal nanoparticles on the nanowire's surface. This leads not only to promising sensor strategies but to a route for understanding some of the fundamental science occurring on these nanoparticles and at the metal/nanowire junction. In particular studying these systems can lead to a better understanding of the influence of the catalyst particle on the electronic structure of the nanowire and its electron transport. This report surveys results obtained so far in this area. In particular, the comparative sensing performance of single quasi-1D chemiresistors (i.e., nanowires or nanobelts) before and after surface decoration with noble metal catalyst particles show significant improvement in sensitivity toward oxidizing and reducing gases. Moreover, one finds that the sensing mechanism can depend dramatically on the degree of metal coverage of the nanowire.     

木质素基金属纳米粒子复合材料的制备及其应用研究进展

木质素是一种最丰富的芳香族天然高分子生物质资源,木质素纳米粒子既具有木质素原本特点,还具有纳米材料的纳米效应等特性,在众多功能材料领域具有很大的潜在应用价值,特别是作为绿色还原剂直接还原金属离子生成木质素基金属纳米粒子复合材料,被广泛应用于催化领域等。本文综述了木质素纳米粒子的制备及其在金属离子还原和金属纳米粒子负载的研究进展,重点综述了木质素基金属纳米粒子复合材料在不同应用领域的研究进展,最后总结并展望了木质素在金属纳米粒子复合材料制备和应用中面临的机遇和挑战。      

负载Pd纳米粒子聚合物颗粒的制备及其催化性能研究

使聚N-乙烯基乙酰胺（PNVA）大分子单体与苯乙烯（St）和丙烯腈（AN）进行三元分散共聚,制得了粒径分布较均一、表面带有花纹状的PNVA-g-PAN/PSt聚合物颗粒,进而以PdCl2为金属源,乙醇为还原剂,采用醇热法将Pd2＋离子还原成Pd纳米粒子并负载于聚合物颗粒表面。透射电子显微镜（TEM）观察表明Pd纳米粒子在聚合物颗粒表面且分布均匀。X射线衍射（XRD）花样图显示Pd纳米粒子为立方晶系,其粒径在9nm左右。热重分析（TGA）结果表明PNVA-g-PAN/PSt聚合物颗粒表面所含Pd纳米粒子的质量分数为0.15%～0.30%。在Pd纳米粒子存在的条件下,可使葡萄糖容易转化为葡萄糖酸,表明该负载型Pd纳米粒子具有良好的催化氧化作用。     

Green synthesis of gold nanoparticles using Citrus maxima peel extract and their catalytic/antibacterial activities

The peel of Citrus maxima (C. maxima) is the primary byproducts during the process of fruit or juice in food industries, and it was always considered as biomass waste for further treatments. In this study, the authors reported a simple and eco‐friendly method to synthesise gold nanoparticles (AuNPs) using C. maxima peel extract as reducing and capping agents. The synthesised AuNPs were characterised by UV–visible spectrum, X‐ray diffraction (XRD), transmission electron microscope (TEM) and Fourier‐transform infrared spectroscopy (FTIR). The UV–visible spectrum of the AuNPs colloid showed a characteristic peak at 540 nm. The peaks of XRD analysis at (2θ) 38.30°, 44.28°, 64.62°, 77.57° and 81.75° were assigned to (111), (200), (220), (311) and (222) planes of the face‐centered cubic (fcc) lattice of gold. The TEM images showed that AuNPs were nearly spherical in shape with the size of 8–25 nm. The FTIR spectrum revealed that some bioactive compounds capped the surface of synthesised AuNPs. The biosynthesised AuNPs performed strong catalytic activity in degradation of 4‐nitrophenol to 4‐aminophenol and good antibacterial activity against both gram negative (Escherichia coli) and gram positive (Staphylococcus aureus) bacterium. The synthesis procedure was proved simple, cost effective and environment friendly.Inspec keywords: gold, nanoparticles, nanofabrication, X‐ray diffraction, ultraviolet spectra, visible spectra, transmission electron microscopy, Fourier transform infrared spectra, crystal structure, catalysis, antibacterial activity, nanobiotechnologyOther keywords: gold nanoparticles, Citrus maxima peel extract, UV–visible spectrum, X‐ray diffraction, transmission electron microscope, Fourier‐transform infrared spectroscopy, XRD analysis, faced centre cubic lattice, TEM images, catalytic activity, 4‐nitrophenol, 4‐aminophenol, antibacterial activity, gram negative bacterium, gram positive bacterium, Au     

贵金属纳米粒子/金属有机骨架复合物的制备与应用进展

贵金属纳米粒子/金属有机骨架复合物因其在催化、传感、气体吸附与存储等诸多领域的应用前景而受到广泛关注.综述了贵金属纳米粒子/金属有机骨架复合物的制备方法及应用进展.对这类复合物的制备方法进行了归纳,并分析了其特点;总结了其在储氢、多相催化等领域的应用,以便更好地了解其应用前景.     

Mechanistic aspects of formation of MgO nanoparticles under microwave irradiation and its catalytic application

This work reports a preparation of Mg(OH)₂ and MgO nanoparticles (NPs) using magnesium acetate in benzylamine and mechanistic study of its formation. The benzylamine acts as a solvent, base, promoter and capping agent in this reaction. The structure and morphology of particles were analyzed by X-ray diffraction pattern (XRD), transmission electron microscopy (TEM), high resolution TEM (HRTEM), selected area energy dispersion (SAED), energy-dispersive X-ray spectroscopy (EDAX), thermogravimetric analysis (TGA), FT-IR, CO₂–temperature programmed desorption (TPD), X-ray photoelectron spectroscopy (XPS) and Brunauer–Emmett–Teller (BET) surface area analysis techniques. The application of as prepared MgO NPs was used in catalysis as a catalyst for the formylation of amines with recyclability studies of nanocatalyst.     

固体推进剂用纳米核壳型铝粉的制备及其应用研究进展

概述了国内外纳米核壳型铝粉复合材料的制备技术及其在固体推进剂中的应用研究进展,讨论了不同制备技术的优缺点以及复合粒子在应用中存在的技术难题和发展前景。     

Synthesis,characterisation and catalytic activity of gold and silver nanoparticles in the bio-sensor application

Most of the hydrogen peroxide (H₂O₂) bio-sensors developed till date are based on enzymes and proteins causing them to have a limited lifetime. Moreover, complex procedures are followed for sensor fabrication. Therefore, an inorganic material-based sensor, with a simple design and longer shelf life is highly desirable. In this work, surfactant-metal (gold and silver) nanoparticles are prepared in aqueous solutions containing cetyltrimethylammonium bromide. The particle sizes of the metal nanoparticles obtained are characterised by UV–Vis, HRTEM, X-ray diffraction and FTIR; the average sizes of gold and silver nanoparticles are 8 and 10?±?0.2?nm, respectively. The nanoparticles are tested for H₂O₂ detection. The sensor is characterised and tested using samples from M to mM H₂O₂ range and a linear response is observed. Low-detection limits and high sensitivity are some of the advantages of this work. Same principle could be extended for the detection of other substrates as well.     

Effect of palladium precursor and preparation method on the catalytic performance of Pd/SiO2 catalysts for benzene hydrogenation

Supported Pd catalysts on silica were prepared by different synthesis methods using Pd(Ac)₂ and PdCl₂ as salts precursors. The obtained materials were characterized by X-Ray Diffraction (XRD), H₂ chemisorption, and temperature programmed desorption of hydrogen (H₂-TPD). The catalytic performances of these catalysts have been evaluated in the hydrogenation of benzene. The obtained results show that metal dispersion and catalytic activity are strongly dependent on the salts precursor and the method of preparation of the catalyst. The catalysts prepared by hydrazine reduction exhibit higher activity in benzene hydrogenation than that by the polyol reduction method. Moreover, the catalyst prepared with palladium acetate showed higher catalytic activity than those prepared with palladium chloride. The superior catalytic performance of this catalyst in the hydrogenation of benzene was ascribed to a significantly better dispersion of Pd particles on the silica support.     

Facile synthesis of near-monodisperse Ag@Ni core-shell nanoparticles and their application for catalytic generation of hydrogen

Magnetically recyclable Ag-Ni core-shell nanoparticles have been fabricated via a simple one-pot synthetic route using oleylamine both as solvent and reducing agent and triphenylphosphine as a surfactant. As characterized by transmission electron microscopy (TEM), the as-synthesized Ag-Ni core-shell nanoparticles exhibit a very narrow size distribution with a typical size of 14.9 ± 1.2 nm and a tunable shell thickness. UV-vis absorption spectroscopy study shows that the formation of a Ni shell on Ag core can damp the surface plasmon resonance (SPR) of the Ag core and lead to a red-shifted SPR absorption peak. Magnetic measurement indicates that all the as-synthesized Ag-Ni core-shell nanoparticles are superparamagnetic at room temperature, and their blocking temperatures can be controlled by modulating the shell thickness. The as-synthesized Ag-Ni core-shell nanoparticles exhibit excellent catalytic properties for the generation of H(2) from dehydrogenation of sodium borohydride in aqueous solutions. The hydrogen generation rate of Ag-Ni core-shell nanoparticles is found to be much higher than that of Ag and Ni nanoparticles of a similar size, and the calculated activation energy for hydrogen generation is lower than that of many bimetallic catalysts. The strategy employed here can also be extended to other noble-magnetic metal systems.     

A review of the preparation and application of magnetic nanoparticles for surface-enhanced Raman scattering

In recent years, the unique properties of magnetic functional nanomaterials have received considerable attentions and show promising applications in separation, detection, diagnosis, catalysis, environment remediation and so on. Specifically, introducing magnetic nanomaterials (MNPs) into traditional sensing techniques greatly simplifies detection operation and improves sensing performances, which makes magnetic nanomaterial-based sensing techniques become a hot research topic. Compared with other sensing techniques such as chromatography, fluorescence, mass spectrum and electrochemistry, surface-enhanced Raman scattering (SERS) displays unique properties of high-sensitivity, fingerprint specificity and nondestructive detection. The introduction of MNPs in SERS has proven to be an efficient way to resolve several critical challenges in practical SERS analysis leading to highly efficient target separation and enrichment, high-sensitive detection and precise outcomes analysis. This makes the MNPs involved SERS analysis a powerful technique with very appealing and promising application in various branches of analytical science. In this review, we first briefly introduced the preparation, encapsulation and surface modification of magnetic nanoparticles, assembly of magnetic nanoparticle–plasmonic substrates and then discussed their applications in SERS analysis, including biomedical application, environmental analysis, food safety and chemical reaction monitoring. Finally, we presented some outlooks on further developments of magnetic nanoparticles in SERS applications.     

The preparation of silver sulfide nanoparticles in lamellar liquid crystal and application to lubrication

The silver sulfide (Ag₂S) nanoparticles were prepared by the reaction of AgNO₃ and Na₂S in the lamellar liquid crystal (LLC) formed by Triton X-100, n-C₁₀H₂₁OH and H₂O. The size of the particles is about 2-3 nm. The existence of Ag₂S nanoparticles can improve the lubrication of the lamellar liquid crystal.     

Photochemical fabrication of size-controllable gold nanoparticles on chitosan and their application on catalytic decomposition of acetaldehyde

In this work, we report a new pathway to prepare size-controllable gold nanoparticles (NPs) on chitosan (Ch) in aqueous solutions for improving catalytic decomposition of acetaldehyde by pure gold NPs at room temperature. First, Au substrates were cycled in deoxygenated aqueous solutions containing 0.1N NaCl and 1 g/L Ch from −0.28 to +1.22 V vs Ag/AgCl at 500 mV/s for 200 scans. Then the solutions were irradiated with UV lights of different wavelengths to prepare size-controllable Au NPs on Ch. Experimental results indicate that the particle sizes of prepared NPs are increased when UV lights with longer wavelengths were employed. The particle sizes of resulted Au NPs can be controlled from 10 to 50 nm. Moreover, the decomposition of acetaldehydes in wines can be significantly enhanced by ca. 190% of magnitude due to the contribution of the adsorption of Au NPs on Ch.     

Zero-valent iron nanoparticles preparation

Zero-valent iron nanoparticles were synthesized by hydrogenating [Fe[N(Si(CH₃)₃)₂]₂] at room temperature and a pressure of 3 atm. To monitor the reaction, a stainless steel pressure reactor lined with PTFE and mechanically stirred was designed. This design allowed the extraction of samples at different times, minimizing the perturbation in the system. In this way, the shape and the diameter of the nanoparticles produced during the reaction were also monitored. The results showed the production of zero-valent iron nanoparticles that were approximately 5 nm in diameter arranged in agglomerates. The agglomerates grew to 900 nm when the reaction time increased up to 12 h; however, the diameter of the individual nanoparticles remained almost the same. During the reaction, some byproducts constituted by amino species acted as surfactants; therefore, no other surfactants were necessary.