Solvothermal preparation,and characterization,of Cu–Ag nanoparticles

Cu–Ag nanoparticles have been successfully synthesized by one-pot solvothermal treatment of a mixture of AgNO₃ and Cu(OAc)₂·H₂O in ethylene glycol solution at 180 °C for 10 h. The samples were characterized by UV–visible absorption, X-ray diffraction (XRD), and extended X-ray absorption fine structure (EXAFS) spectroscopy, transmission electron microscopy (TEM), and energy-dispersive X-ray spectroscopy (EDS). The results showed that Cu–Ag nanoparticles and a small amount of phase-separated Cu–Ag alloy nanoparticles with an average diameter of 100 ± 30 nm were synthesized by the solvothermal treatment procedure. The mechanism of formation is discussed.     

Solvent-Free Synthesis of ZnO Nanoparticles by a Simple Thermal Decomposition Method

This paper reports on a novel processing route for producing ZnO nanoparticles by solid-state thermal decomposition of zinc(II) acetate nanostructures obtained by the sublimation of zinc(II) acetate powder. The sublimation process of the Zn(OAc)₂ powder was carried out in the temperature 150 °C for 2 h. In addition, nanoparticles of ZnO were obtained by solid-state thermal decomposition of the synthesized Zn(OAc)₂ nanostructures. The synthesized products were characterized by X-ray diffraction (XRD), scanning electron microscopy, transmission electron microscopy, photoluminescence spectroscopy, and energy dispersive X-ray spectroscopy. The sublimation process of the Zn(OAc)₂ powder was carried out within the range of 150–180 °C. The XRD studies indicated the production of pure hexagonal ZnO nanoparticles after thermal decomposition.     

Antibacterial behavior and physical properties of silver nanoparticle-doped ecofriendly nonwoven fabrics

A green approach for forming silver nanoparticles (Ag NPs) on ecofriendly highly absorbent nonwoven fabrics was investigated. The fiber blending ratio of highly absorbent nonwoven fabrics was optimized by simulated body fluid (SBF) and water absorption. SBF and water absorption ratios reached 42 and 42.9 times after addition of 50 wt% highly absorbent fibers. The Ag NPs were characterized by UV-visible spectrometry (UV-Vis), X-ray diffraction (XRD) and transmission electron microscopy (TEM). UV-Vis and XRD images confirmed the presence of Ag NPs. TEM observation revealed that Ag NPs were distributed at 5–10 nm. The results of antimicrobial activity showed that Ag NP dope is effective for producing antimicrobial nonwoven fabrics against E. coli and S. aureus.     

Synthesis of ZnO/NiO nanocomposites from ethanol solutions

We propose a process for the synthesis of ZnO/NiO nanocomposites from ethanolic solutions by means of consecutive generation of ZnO and NiO nanoparticles. X-ray powder diffraction (XRD) and transmission electron microscopy (TEM) show that in the range 400–900°C, nanocomposites are two-phase mixtures of particles of hexagonal and cubic phases with ZnO dissolved in NiO; at 1000°C, Ni_0.5Zn_0.5O single-phase solid solution is generated. The mean particle size determined from TEM data and diffraction peak broadening increases with rising temperature. In the cathodoluminescence spectrum of a sample annealed at 400°C, the luminescence peak shifts to the UV. Specific magnetization versus magnetic field measurements in nanocomposites show hysteresis; the coercive force reaches 200 Oe.     

Size‐Controlled Synthesis of Highly Monodisperse Gold Nanoparticles without a Size‐Selection and Long Range Ordered 2‐D Arrangement

A simple method is used to control the size of cetyltrimethylammoniumbromide‐protected Au nanoparticles by a reversal micelle in safe organic solvent. These Au nanoparticles can be evolved to highly monodisperse Au nanoparticles capped 1‐dodecanthiol in the 2, 3, and 5 nm diameter by refluxing at～160°C for 7 hours. Their ultraviolet visible spectroscopy (UV‐vis), x‐ray diffraction (XRD, transmission electron microscopy (TEM) showed that all the three different size gold nanoparticles(NPs) displayed high size homogenous properties and easy formed large areas of long ordered two‐dimensional arrangement at the air/solid interface.     

Combustion synthesis of calcium doped ZnO nanoparticles for the photocatalytic degradation of methylene blue dye

ZnO nanoparticles are one of the prominent photocatalysts for environmental applications due to its high redox ability, nontoxic and higher stability. This report explains the synthesis of ZnO nanoparticles by a simple solution combustion method using zinc nitrate hexahydrate as an oxidizing agent and incense stick powder as fuel at 400 °C. Several techniques were adopted for the characterization of the obtained product. X-ray diffraction (XRD) pattern shows that a lower concentration of fuel gives pure ZnO and a higher concentration of fuel results in calcium doped ZnO with a cubic phase having a crystallite size of 32–28 nm. UV–vis spectrum shows that as the fuel concentration increases, band gap decreases and reaches to 3.33 eV for 3 g of fuel. Spongy networks with many pores wereobserved in the scanning electron microscope (SEM) and transmission electron microscope (TEM) images showed the average particle size of Ca doped ZnO NPs is about 20 nm. Pure and Ca doped ZnO nanoparticles were examined for photocatalytic degradation of methylene blue (MB) dye under UV light irradiation. The results prove that Ca doped ZnO nanoparticles show good photocatalytic activity.     

不同形貌ZnO纳米粒子的超声化学法制备与表征

One-dimensional ZnO nanorods and shuttle-like ZnO nanoparticles have been successfully achieved by ultrasonic irradiation of Zn (CH3COO)2 aqueous solution and Zn-NH3 complexcs solution. The obtained ZnO nanoparticles have been characterized using X-ray diffraction (XRD), transmission electron microscopy (TEM) and selected area electronic diffraction (SAED). And the formative mechanism of the prepared different morphological ZnO nanoparticles is also discussed under ultrasonic irradiation.     

Calcination temperature-dependent morphology of photocatalytic ZnO nanoparticles prepared by an electrochemical–thermal method

ZnO nanoparticles (NPs) with tunable morphologies were synthesized by a hybrid electrochemical–thermal method at different calcination temperatures without the use of any surfactant or template. The NPs were characterized by Fourier transform infrared (FT-IR) spectroscopy, X-ray diffraction, dynamic light scattering, thermogravimetry–differential thermal analysis, scanning electron microscope and N₂ gas adsorption–desorption studies. The FT-IR spectra of ZnO NPs showed a band at 450 cm^?1, a characteristic of ZnO, which remained fairly unchanged at calcination temperatures even above 300 °C, indicating complete conversion of the precursor to ZnO. The products were thermally stable above 300 °C. The ZnO NPs were present in a hexagonal wurtzite phase and the crystallinity of ZnO increased with an increasing calcination temperature. The ZnO NPs calcined at lower temperature were mesoporous in nature. The surface areas of ZnO NPs calcined at 300 and 400 °C were 51.10 and 40.60 m² g^?1, respectively, which are significantly larger than commercial ZnO nanopowder. Surface diffusion has been found to be the key mechanism of sintering during heating from 300 to 700 °C with the activation energy of sintering as 8.33 kJ mol^?1. The photocatalytic activity of ZnO NPs calcined at different temperatures evaluated by photocatalytic degradation of methylene blue under sunlight showed strong dependence on the surface area of ZnO NPs. The ZnO NPs with high surface area showed enhanced photocatalytic activity.     

Photocatalytic studies of silver doped ZnO nanoparticles synthesized by chemical precipitation method

Ag-doped ZnO nanoparticles (Zn_1?xAg_xO; where x = 0.00–0.05) were synthesized by chemical precipitation method. The synthesized products were characterized by X-ray diffraction, scanning electron microscope (SEM), transmission electron microscope (TEM) and UV–Vis spectrometer. The SEM and TEM micrographs revealed the agglomerated spherical-like morphology and the measurements show that the size of crystallites is in the range of 10–40 nm. Optical measurements indicated a red shift in the absorption band edge after Ag doping. The band gap values of as prepared undoped and doped with silver samples were found to decrease with increase in temperature from 300 to 800 °C. Photocatalytic activities of ZnO and Ag doped ZnO were evaluated by irradiating the sample solution to ultraviolet light by taking methylene blue as organic dye. The experiment demonstrated that the photo-degradation efficiency of 1 mol% Ag-doped ZnO was significantly higher than that of undoped and 2–5 mol% Ag doped ZnO under ultraviolet light irradiation.     

Biogenic Synthesis of CuO,ZnO, and CuO–ZnO Nanoparticles Using Leaf Extracts of Dovyalis caffra and Their Biological Properties

Biogenic metal oxide nanoparticles (NPs) have emerged as a useful tool in biology due to their biocompatibility properties with most biological systems. In this study, we report the synthesis of copper oxide (CuO), zinc oxide (ZnO) nanoparticles (NPs), and their nanocomposite (CuO–ZnO) prepared using the phytochemical extracts from the leaves of Dovyalis caffra (kei apple). The physicochemical properties of these nanomaterials were established using some characterization techniques including X-ray diffraction analysis (XRD), ultraviolet-visible spectroscopy (UV-vis), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and energy-dispersive X-ray spectroscopy (EDX). The XRD result confirmed the presence of a monoclinic CuO (Tenorite), and a hexagonal ZnO (Zincite) nanoparticles phase, which were both confirmed in the CuO–ZnO composite. The electron microscopy of the CuO–ZnO, CuO, and ZnO NPs showed a mixture of nano-scale sizes and spherical/short-rod morphologies, with some agglomeration. In the constituent’s analysis (EDX), no unwanted peak was found, which showed the absence of impurities. Antioxidant properties of the nanoparticles was studied, which confirmed that CuO–ZnO nanocomposite exhibited better scavenging potential than the individual metal oxide nanoparticles (CuO, and ZnO), and ascorbic acid with respect to their minimum inhibitory concentration (IC₅₀) values. Similarly, the in vitro anticancer studies using MCF7 breast cancer cell lines indicated a concentration-dependent profile with the CuO–ZnO nanocomposite having the best activity over the respective metal oxides, but slightly lower than the standard 5-Fluorouracil drug.     

Preparation and characterization of novel polyimide/functionalized ZnO bionanocomposite for gas separation and study of their antibacterial activity

In the present investigation novel Polyimide/functionalized ZnO (PI/ZnO) bionanocomposites containing amino acid (Methionine) and benzimidazole pendent groups with different amounts of modified ZnO nanoparticles (ZnO NPs) were successfully prepared through ultrasonic irradiation technique. Due to the high surface energy and tendency for agglomeration, the surface ZnO NPs was modified by a coupling agent as 3- methacryloxypropyl-trimethoxysilane (MPS) to form MPS-ZnO nanoparticles. The ultrasonic irradiation effectively changes the rheology and the glass transition temperature and the crystallinity of the composite polymer. PI/ZnO nanocomposites were characterized by Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), scanning electron microscopy (SEM) and transmission electron microscope (TEM). TEM analysis showed that the modified ZnO nanoparticles were homogeneously dispersed in polymer matrix. The TGA results of PI/ZnO nanocomposites showed that the thermal stability is obviously improved the presence of MPS-ZnO NPs in comparison with the pure PI and that this increase is higher when the NP content increases. The permeabilities of pure H₂, CH₄, O₂, and N₂ gases through prepared membranes were determined at room temperature (25 °C) and 20 bar feed pressure. The membranes having 20% ZnO showed higher values of H₂ permeability, and H₂/CH₄ and H₂/N₂ ideal selectivities (the ratio of pair gas permeabilities) compared with other membranes. The antibacterial activity of bionanocomposite films was tested against gram-positive bacteria (Staphylococcus aureus and Bacillus subtilis) and gram-negative bacteria (Escherichia coli and Pseudomonas aeruginosa). Further, it was observed that antibacterial activity of the resulting hybrid biofilms showed somewhat higher for gram-positive bacteria compared to gram-negative bacteria.     

The controllable preparation of electrospun carbon fibers supported Pd nanoparticles catalyst and its application in Suzuki and Heck reactions

The palladium nanoparticles/carbon nanofibers(Pd NPs/CNFs) catalyst was prepared by the electrospinning method, the hydrazine hydrate solution reduction in an ice bath environment, the high temperature carbonization. The catalyst was characterized by X-ray diffraction(XRD), fieldemission scanning electron microscope(FE-SEM), and transmission electron microscopy(TEM). The nanofibers are not cross-linked and arranged in order. The surface of Pd NPs/CNFs is smooth, and it can be observed that a large number of particles were loaded and well-dispersed in carbon fiber matrix, and the particle distribution is uniform. The activity center of catalyst is Pd(0). The Pd NPs/CNFs exhibited a high efficiency, good reusability and stability in the Suzuki and Heck reactions. It can be used for at least five consecutive runs without significant loss of its catalytic activity. The good recyclability of Pd NPs/CNFs provides a way to greatly reduce the cost of the catalyst.     

Electrodeposition of silver nanoparticles on a zinc oxide film: improvement of amperometric sensing sensitivity and stability for hydrogen peroxide determination

A strategy to fabricate a hydrogen peroxide (HP) sensor is developed by electrodepositing silver nanoparticles (Ag NPs) on a modified glassy carbon electrode (GCE) with a zinc oxide (ZnO) film. The Ag NPs/ZnO/GCE has been characterized by scanning electron microscopy, cyclic voltammetry, and chronoamperometry. It has been found that the Ag NPs synthesized in the presence of ZnO film provide an electrode with enhanced sensitivity and excellent stability. The sensitivity to HP is enhanced 3-fold by using Ag NPs/ZnO/GCE compared to Ag NPs/GCE. The HP sensor exhibits good linear behavior in the concentration range 2 µM to 5.5 mM for the quantitative analysis of HP with a detection limit of 0.42 µM (S/N?=?3).     

The surface modification of spherical ZnO with Ag nanoparticles: A novel agent,biogenic synthesis,catalytic and antibacterial activities

Nowadays, the industrial wastewater pollutants including toxic dyes and pathogenic microbes have caused serious environmental contaminations and human health problems. In the present study, eco-friendly and facile green synthesis of Ag modified ZnO nanoparticles (ZnO-Ag NPs) using Crataegus monogyna (C. monogyna) extract (ZnO-Ag@CME NPs) is reported. The morphology and structure of the as-biosynthesized product were characterized by field emission scanning electron microscopy (FESEM), X-Ray diffraction (XRD), differential reflectance spectroscopy (DRS), dynamic light scattering (DLS), transmission electron microscopy (TEM), Fourier-transform infrared spectroscopy (FT-IR), and energy-dispersive X-ray spectroscopy (EDS) techniques. TEM and FESEM images confirmed the oval and spherical-like structure of the products with a size of 55–70 nm. The EDS analysis confirmed the presence of Zn, Ag, and O elements in the biosynthesized product. The photocatalytic results showed ZnO-Ag@CME NPs were degraded (89.8% and 75.3%) and (94.2% and 84.7%) of methyl orange (MO) and basic violet 10 (BV10), under UV and sunlight irradiations, respectively. The Ag modified ZnO nanoparticles exhibited enhanced catalytic activity towards organic pollutants, and showed better performance than the pure ZnO nanoparticles under UV and sunlight irradiations. This performance was probably due to the presence of silver nanoparticles as a plasmonic material. Antibacterial activity was performed against different bacteria. ZnO-Ag@CME NPs showed high antibacterial activity against K. pneumoniae, S. typhimurium, P. vulgaris, S. mitis, and S. faecalis with MIC values of 50, 12.5, 12.5, 12.5, and 12.45 µg/mL, respectively. All in all, the present investigation suggests a promising method to achieve high-efficiency antibacterial and catalytic performance.     

Synthesis of CuS and ZnO/Zn(OH)2 nanoparticles and their evaluation for in vitro antibacterial and antifungal activities

In this study, the copper sulfide nanoparticles (CuS‐NPs) and the zinc oxide/zinc hydroxide nanoparticles ((ZnO/Zn(OH)₂‐NPs) were synthesized by a simple and low‐cost method, and the synthesized nanoparticles were characterized and identified by UV–Vis, field emission scanning electron microscopy (FE‐SEM), transmission electron microscopy (TEM) and X‐ray diffraction (XRD). The antimicrobial activity of the CuS‐NPs and the ZnO/Zn(OH)₂‐NPs were examined by broth dilution to determine the minimal inhibitory concentration (MIC) of antibacterial agent required to inhibit the growth of a pathogen and the minimum bactericidal concentration (MBC) required to kill a particular bacterium. Agar disc diffusion method was used to determine the zone of inhibition. The nanoparticles demonstrated potent antibacterial activity against Klebsiella pneumonia (ATCC 1827), Acinetobacter baumannii (ATCC 150504), Escherichia coli (ATCC 33218) and Staphylococcus aureus (ATCC 25293). Antifungal activity against Aspergillus oryzae (PTCC 5164) was also obtained. The data obtained from antimicrobial activities by broth dilution and agar disc diffusion methods exhibited the CuS‐NPs were more effective than the ZnO/Zn(OH)₂‐NPs. A good correlation was observed between the data obtained by both methods.     

Zinc Oxide Nanoparticle‐modified Glassy Carbon Electrode as a Highly Sensitive Electrochemical Sensor for the Detection of Caffeine

Zinc oxide nanoparticles (ZnO NPs ) were prepared by a simple, convenient, and cost‐effective wet chemical method using the biopolymer starch. The prepared ZnO NPs were characterized by X‐ray diffraction (XRD ), scanning electron microscopy (SEM ), energy‐dispersive X‐ray (EDX ), Fourier transform infrared (FT‐IR ), and UV ‐visible spectroscopic techniques. The average crystallite size calculated from XRD data using the Debye–Scherer equation was found to be 15 nm. The electrochemical behavior of caffeine (CAF ) was studied using a glassy carbon electrode (GCE ) modified with zinc oxide nanoparticles by cyclic voltammetry (CV ) and differential pulse voltammetry (DPV ). Compared to unmodified GCE , ZnO NPs‐ modified GCE (ZnO NPs MGCE ) exhibited excellent electrocatalytic activity towards CAF oxidation, which was evident from the increase in the peak current and decrease in the peak potential. Electrochemical impedance study suggested that the charge‐transfer capacity of GCE was significantly enhanced by ZnO NPs . The linear response of the peak current on the concentrations of CAF was in the range 2–100 μM . The detection limit was found to be 0.038 μM. The proposed sensor was successfully employed for the determination of CAF in commercial beverage samples.     

Aerobic oxidation of benzyl alcohols through biosynthesized palladium nanoparticles mediated by Oak fruit bark extract as an efficient heterogeneous nanocatalyst

In this study, green synthesis of Pd nanoparticles (NPs) is outlined through application of Oak fruit bark extract as a reducing, capping and stabilizing agent. The characteristics and properties of the biosynthesized Pd NPs were revealed by FESEM, EDX, XRD, TEM, UV–Vis, and FT-IR spectroscopies. So that, UV–Vis spectroscopy of the Pd colloidal solution confirmed reduction of Pd ions, and XRD and TEM analysis identified fcc unit cell structure forming 5–7 nm spherical Pd NPs. Furthermore, catalytic activity of the prepared catalyst was investigated through aerobic oxidation of alcohols, as model reactions. Catalytic evaluations demonstrated achievement of good yields from primary and secondary benzyl alcohols. In general, the devised synthesis method is advantageous from several perspectives. For example, the synthesized catalysts give high product yields and are efficient, they eliminate the need for surfactant, chemical reductants, ligand and organic solvents, the approach is economically inexpensive, it results in cleaner reaction profiles, application of the simply prepared heterogeneous catalyst is convenient, and the catalyst is recoverable and reusable for at least six times without any significant loss of its catalytic activity.     

Surfactant-free thermal decomposition route to phase pure tricobalt tetraoxide nanoparticles from cobalt(II)-tartrate complex

Tricobalt tetraoxide nanoparticles have been successfully synthesized following a ‘bottom-up’ approach by surfactant-free thermal decomposition of cobalt(II)-tartrate complex obtained by a modified sol–gel route. The synthesized complex was characterized by Fourier transform infrared (FT-IR) spectroscopy, elemental and thermogravimetric-differential thermal analysis (TG–DTA). The nanoparticles were characterized by powder X-ray diffraction (XRD), transmission electron microscopy (TEM), and Raman studies. The powder XRD pattern furnished evidence for a face-centered cubic structure of Co₃O₄. With the rise in calcination temperature from 400 through 500 to 600 °C, the average crystallite sizes of Co₃O₄ were found to increase from 28 through 36 to 46 nm. The TEM image revealed a faceted morphology of the as-synthesized Co₃O₄ nanoparticles. The high-resolution TEM image indicated the interplanar separation to be 0.28 nm which corresponds to the (220) plane in face-centered cubic Co₃O₄. The electron diffraction (ED) pattern showed single-crystalline nature of the synthesized nanoparticles. Raman spectrum showed four characteristic peaks of Co₃O₄ which further confirmed the phasic purity of the material.     

Low temperature carbon monoxide catalytic oxidation at the Pd/Ce–Zr–Al–Ox catalyst

The homogeneous chemical composition ceria–zirconia–alumina (Ce–Zr–Al–O_x) nano-alloy were successfully synthesized by surfactant-assisted parallel flow co-precipitation method and applied as supports for low temperature CO oxidation. The experiment conditions were studied in detailed. At 0.92 wt% Pd loading, 30,000 ppm CO could be completely oxidized to CO₂ at 30 °C at a WHSV of 4,380 ml g^?1 h^?1 over the Pd/Ce–Zr–Al–O_x (n_Ce:n_Zr = 3:1) catalyst. Pd/Ce–Zr–Al–O_x catalysts were systematical studied by mean of BET, XRD and TEM analysis. XRD characterization showed that zirconium element entered into cubic structure of ceria and leaded to structure distortion. Addition of aluminum increased specific surface area of ceria–zirconia solid solution substantially. The average pore diameter of Ce–Zr–Al–O_x support palladium catalysts were the key impact factor for CO oxidation. When the Pd/Ce–Zr–Al–O_x catalysts had highly dispersed palladium nanoparticles, large average pore diameter, suitable surface area and pore volume, the activity of CO oxidation was the best.     

Facile fabrication of ZnO/N‐doped helical carbon nanotubes composites with enhanced photocatalytic activity toward organic pollutant degradation

Novel ZnO/N‐doped helical carbon nanotubes (ZnO/N‐HCNTs) composites were successfully synthesized via a facile chemical precipitation approach at room temperature. The sample was well characterized by X‐ray diffraction (XRD), energy dispersive X‐ray spectroscopy (EDS), transmission electron microscopy (TEM) and ultraviolet–visible diffuse reflectance spectroscopy (UV–vis DRS). The photocatalytic activity was evaluated in the degradation of methylene blue (MB) aqueous solution under UV light irradiation. It is found that ZnO nanoparticles were highly and uniformly anchored on the surface and inner tubes of the N‐HCNTs with size of about 5 nm, and significantly enhanced the photocatalytic activity compared to pure ZnO. The enhanced photocatalytic activity of ZnO/N‐HCNTs composites can be ascribed to the integrative synergistic effect of effective interfacial hybridization between N‐HCNTs and ZnO nanoparticles and the prolonged lifetime of photogenerated electron–hole pairs. Moreover, the ZnO/N‐HCNTs could be easily recycled without any obvious decrease in photocatalytic activity and could be promote their application in the area of environmental remediation.