scholarly journals Synthesis of Hollow PVP/Ag Nanoparticle Composite Fibers via Electrospinning under A Dense CO2 Environment

Polymers ◽  
2021 ◽  
Vol 14 (1) ◽  
pp. 89
Author(s):  
Xin Hu ◽  
Jiayang He ◽  
Li Zhu ◽  
Siti Machmudah ◽  
Wahyudiono Wahyudiono ◽  
...  
Keyword(s):  
Photoelectron Spectroscopy ◽  
Hollow Structure ◽  
Feed Solution ◽  
Composite Fibers ◽  
Ag Nps ◽  
X Ray ◽  
Carbon Dioxide Co2 ◽  
Sonochemical Reduction ◽  
Average Size ◽  
Co2 Environment

Polyvinylpyrrolidone (PVP) is used in a wide variety of applications because of its unique chemical and physical features, including its biocompatibility and low toxicity. In this study, hollow PVP/silver nanoparticle (PVP/Ag NP) composite fibers were synthesized. Stable, spherical Ag NPs, with an average size of 14.4 nm, were produced through a facile sonochemical reduction method. A small amount of starch as a potent reducing and stabilizing agent was used during the reduction of Ag ions to Ag NPs. The fabricated Ag NPs were then added to a 10 wt% PVP-dichloromethane (DCM) solution, which was utilized as an electrospinning feed solution under a dense carbon dioxide (CO2) environment at 313 K and 5 MPa and an applied voltage of 15 kV. The dense CO2 enabled rapid extraction of DCM from the PVP-Ag NPs-DCM solution, which was then dissolved into PVP/Ag NPs, resulting in a hollow structure. Scanning electron microscopy, Fourier-transform infrared (FT-iR) spectroscopy, X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS) analyses, and thermogravimetric analysis (TGA), were used to characterize the electrospinning products.

scholarly journals {CeO2/Bi2Mo1−xRuxO6} and {Au/Bi2Mo1−xRuxO6} Catalysts for Low-Temperature CO Oxidation

Catalysts ◽  
2019 ◽  
Vol 9 (11) ◽  
pp. 947 ◽  
Author(s):  
Edson Edain González ◽  
Ricardo Rangel ◽  
Javier Lara ◽  
Pascual Bartolo-Pérez ◽  
Juan José Alvarado-Gil ◽  
...  
Keyword(s):  
Co Oxidation ◽  
Photoelectron Spectroscopy ◽  
Supported Catalysts ◽  
Pollutant Emissions ◽  
Impregnation Method ◽  
Wet Impregnation ◽  
X Ray ◽  
Low Temperature Co Oxidation ◽  
Carbon Dioxide Co2 ◽  
Wet Impregnation Method

Nowadays, one of the most important challenges that humanity faces is to find alternative ways of reducing pollutant emissions. CeO2/Bi2Mo1−xRuxO6 and Au/Bi2Mo1−xRuxO6 catalysts were prepared to efficiently transform carbon monoxide (CO) to carbon dioxide (CO2) at low temperatures. The systems were prepared in a two-step process. First, Bi2Mo1−xRuxO6 supports were synthesized through the hydrothermal procedure under microwave heating. Then, CeO2 was deposited on Bi2Mo1−xRuxO6 using the wet impregnation method, while the incipient impregnation method was selected to deposit gold nanoparticles. The CeO2/Bi2Mo1−xRuxO6 and Au/Bi2Mo1−xRuxO6 catalysts were characterized using SEM microscopy and XRD. Furthermore, energy-dispersive X-ray spectroscopy (EDS), X-ray photoelectron spectroscopy (XPS), and Raman spectroscopy were used. Tests were carried out for the supported catalysts in CO oxidation, and high conversion values, nearing 100%, was observed in a temperature range of 100 to 250 °C. The results showed that the best system was the Au/Bi2Mo0.95Ru0.05O6 catalyst, with CO oxidation starting at 50 °C and reaching 100% conversion at 186 °C.

scholarly journals Aerobic Oxidation of 5-Hydroxymethylfurfural over Ag Nanoparticle Catalysts Stabilized by Polyvinylpyrrolidone with Different Molecular Weights

Nanomaterials ◽  
2020 ◽  
Vol 10 (9) ◽  
pp. 1624
Author(s):  
Haian Xia ◽  
Jiahuan An ◽  
Weizi Zhang
Keyword(s):  
Catalytic Activity ◽  
Photoelectron Spectroscopy ◽  
Catalytic Properties ◽  
Aerobic Oxidation ◽  
Ag Nps ◽  
Oxidation Activity ◽  
X Ray ◽  
Remarkable Effect ◽  
Molecular Weights ◽  
Metal Support Interaction

The metal–support interaction (MSI) has a remarkable effect on the catalytic properties, but how to precisely modulate its degree remains a huge challenge. Herein, polyvinylpyrrolidone (PVP) with three different molecular weights (MWs) (24, 58, and 130 kDa) was used as a capping agent to fabricate Ag nanoparticles (NPs) supported on ZrO2. The physiochemical properties of the catalysts were characterized by X-ray diffraction (XRD), Transmission Electron Microscope (TEM), X-ray Photoelectron Spectroscopy (XPS), and Fourier transform infrared (FT-IR) techniques. The impacts of MSI on the catalytic activity and reaction kinetics for aerobic oxidation of 5-hydroxymethylfurfural (HMF) were investigated. The results showed that the introduction of PVP with various MWs could efficiently tailor the interfacial interactions and charge transfers (CT) among PVP, the support, and Ag NPs, thereby affecting the oxidation activity of HMF. The turnover number (TON) for HMF oxidation decreases in the order of unsupported colloidal Ag clusters > Ag/ZrO2 (58,000) > Ag/ZrO2 (130,000) > Ag/ZrO2 (24,000) > Ag/ZrO2. The reason for this large difference in the catalytic activity for HMF oxidation is that various MWs of PVP result in a change of MSI, thereby facilitating CT from PVP to Ag metal sites. This study offers a new strategy for modulating MSI by varying the MW of capping agents, thereby tuning the catalytic properties in the oxidation of HMF.

Preparation and characterization of polyphenylene sulfide/graphene nanoplatelets composite fibers with enhanced oxidation resistance

2019 ◽  
Vol 32 (4) ◽  
pp. 394-405 ◽  
Author(s):  
Jian Xing ◽  
Zhenzhen Xu ◽  
Qing-Qing Ni ◽  
Huizhen Ke
Keyword(s):  
Oxidation Resistance ◽  
Photoelectron Spectroscopy ◽  
Melt Spinning ◽  
Retention Rate ◽  
Graphene Nanoplatelets ◽  
Polyphenylene Sulfide ◽  
Degree Of Crystallinity ◽  
Composite Fibers ◽  
Oxidation Treatment ◽  
X Ray

Composite masterbatches of polyphenylene sulfide (PPS) with functionalized graphene nanoplatelets (GNPs) were prepared by melt blending via a twin-screw extruder. The structure and morphology of composite masterbatches were characterized by scanning electron microscopy and X-ray diffraction analysis. The PPS/functionalized GNPs composite fibers were then manufactured by a self-made spinning equipment via melt spinning. The oxidation resistance and other properties of PPS composite fibers were also examined. The results showed that the pure PPS fibers exhibited smooth surface, whereas the surface of PPS/functionalized GNPs composite fibers was rough. The addition of functionalized GNPs could be acted as heterogeneous nucleating agents to improve the crystallization and increase the degree of crystallinity. The retention rate of breaking strength of PPS/functionalized GNPs composite fibers could maintain up to 85% after the oxidation treatment. The improvement in the oxidation resistance of PPS/functionalized GNPs composite fibers is the results of comprehensive effects characterized by the X-ray photoelectron spectroscopy analyses. The addition of functionalized GNPs could limit the damage of the C–S group and retard the generation of sulfuryl groups (–SO–) during the oxidation treatment. The chemical combination of the elements sulfur (S) and oxygen (O) could also be restricted, thus weakening the oxidation activity.

Preparation and Characterization of CdSe Nanoparticles Synthesized Using the Ultrasonic Irradiation

2007 ◽  
Vol 124-126 ◽  
pp. 1229-1232 ◽  
Author(s):  
Myoung Seok Sung ◽  
Yoon Bok Lee ◽  
Yong Jin Kim ◽  
Yang Do Kim
Keyword(s):  
Ultrasonic Irradiation ◽  
Photoelectron Spectroscopy ◽  
Irradiation Time ◽  
Xrd Analysis ◽  
Cdse Nanoparticles ◽  
X Ray Diffraction ◽  
X Ray ◽  
Surface Emission ◽  
Transmission Electron ◽  
Average Size

Cadmium selenide(CdSe) nanoparticles were prepared in the aqueous solution containing isopropyl alcohol by the ultrasonic irradiation at room temperature. The cadmium chloride (CdCl2) and sodium selenosulfate (Na2SeSO3) were used as the cadmium and selenium source, respectively. X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), transmission electron microscopy (TEM), UV-Vis absorption spectra and PL spectra were used to characterize the CdSe nanoparticles. XRD analysis revealed the formation of cubic structure CdSe. TEM images showed aggregated CdSe nanoparticles with the size of nanometer scale. Average size of CdSe nanoparticles were about 3.9, 5.0 and 5.1nm with sonication time of 6, 30 and 40 minutes, respectively. The surface emission became less intensive and shifted to red with increasing irradiation time. This paper presents the effects of ultrasonic on the formation of CdSe nanoparticles and its characteristics.

scholarly journals CO Preferential Photo-Oxidation in Excess of Hydrogen in Dark and Simulated Solar Light Irradiation over AuCu-Based Catalysts on SBA-15 Mesoporous Silica-Titania

Materials ◽  
2018 ◽  
Vol 11 (7) ◽  
pp. 1203 ◽  
Author(s):  
Isabel Barroso-Martín ◽  
Antonia Infantes-Molina ◽  
Aldo Talon ◽  
Loretta Storaro ◽  
Elena Rodríguez-Aguado ◽  
...  
Keyword(s):  
Photoelectron Spectroscopy ◽  
Light Irradiation ◽  
Solar Light ◽  
X Ray ◽  
Preferential Oxidation Of Co ◽  
Simulated Solar Light ◽  
Solar Light Irradiation ◽  
Vis Spectroscopy ◽  
Average Size ◽  
Adsorption Desorption

In this work, SBA-15 silica and silica-titania have been used as supports for photocatalysts based on AuCu alloy (Au:Cu = 1) to be used in the preferential oxidation of CO (CO-PROX) in excess of hydrogen at room temperature and atmospheric pressure both in the dark and under simulated solar light irradiation. To study their textural, structural, chemical and optical properties, the samples were characterized by X-ray diffraction (XRD), high-resolution transmission electron microscopy (HR-TEM), adsorption-desorption of N2 at −196 °C, 13C and 29Si solid state nuclear magnetic resonance (NMR), X-ray photoelectron spectroscopy (XPS) and diffuse reflectance ultraviolet-visible (DRUV-vis) spectroscopy. Titanium was present mainly in the form of titania aggregates, but also as small particles interacting with the SBA support. In both catalysts, the metal alloy nanoparticles displayed an average size of 4 nm as demonstrated by TEM measurements. AuCu/Ti-SBA turned out to be photoactive and selective in the photo-CO-PROX reaction showing the highest activity, with conversion and selectivity towards CO2 of 80%, due both to the presence of titania incorporated in SBA-15 and to the synergistic effect of Cu when alloyed with Au.

A COST-EFFECTIVE MAGNETIC PHOTOCATALYST PALYGORSKITE–TiO2–FexOy WITH EXCELLENT PERFORMANCE FOR DYE PHOTODEGRADATION UNDER VISIBLE LIGHT

NANO ◽  
2014 ◽  
Vol 09 (06) ◽  
pp. 1450063
Author(s):  
JIAHUI ZHANG ◽  
LILI ZHANG ◽  
JIN HUANG ◽  
SHOUYONG ZHOU ◽  
HAIQUN CHEN ◽  
...  
Keyword(s):  
Visible Light ◽  
Photoelectron Spectroscopy ◽  
Cost Effective ◽  
Magnetic Photocatalyst ◽  
X Ray ◽  
Transmission Electron ◽  
Light Region ◽  
Reaction Solution ◽  
Excellent Photocatalytic Activity ◽  
Average Size

Palygorskite (denoted as Pal) was used as an economical carrier of hybrid photocatalyst TiO 2– Fe x O yvia an in situ depositing technique (marked as Pal– TiO 2– Fe x O y). The samples were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), brunner-emmet-teller (BET) measurements, X-ray photoelectron spectroscopy (XPS) and UV-Vis diffuse reflectance spectra measurements. Results showed that TiO 2– Fe x O y composite particles with average size of about 10 nm were loaded onto the Pal fibers' surface. Fe x O y acted not only as magnetic source but also took part in the formation of TiO 2– Fe x O y heterojunction structure, which resulted in the obvious absorption in visible light region for the obtained Pal– TiO 2– Fe x O y composite photocatalyst. The obtained Pal– TiO 2– Fe x O y shows excellent photocatalytic activity toward photodegradation of Methyl orange (MO) under visible light irradiation and the degradation ratio reached 94% within 180 min. Moreover, Pal– TiO 2– Fe x O y could be readily recovered from the reaction solution by the magnet. Possible mechanism for the enhancement was also proposed.

Fabrication of cotton fabrics with durable antibacterial activities finishing by Ag nanoparticles

2018 ◽  
Vol 89 (5) ◽  
pp. 867-880 ◽  
Author(s):  
Yunping Wu ◽  
Yan Yang ◽  
Zhijie Zhang ◽  
Zhihua Wang ◽  
Yanbao Zhao ◽  
...  
Keyword(s):  
Photoelectron Spectroscopy ◽  
Inductively Coupled Plasma ◽  
Antibacterial Properties ◽  
Antimicrobial Activities ◽  
Cotton Fabrics ◽  
Synthesis Process ◽  
Ag Nps ◽  
X Ray ◽  
E Coli ◽  
Fabric Surface

In this paper, we propose a facile and mild route to prepare size-tunable silver nanoparticles (Ag NPs) and their finishing application on fabrication of antibacterial cotton fabrics. The as-prepared Ag NPs, with an average particles size of 2.3 nm, show the minimal inhibitory concentration of 7.8 µg/mL and the minimum bactericidal concentration of 15.6 µg/mL, respectively. In this study, sodium citrate served as a stabilizing agent to prevent Ag NP agglomeration in the synthesis process, and citric acid acted as a binder to fix Ag NPs on the cotton fabrics through chemical bonds in the finishing process. The results of Fourier transform infrared spectroscopy, ultraviolet-visible spectroscopy (UV-vis), X-ray diffraction, X-ray photoelectron spectroscopy, scanning electron microscopy, and energy-dispersive X-ray spectroscopy demonstrate that Ag NPs have been fixed and well dispersed on the cotton fabric surface. Ag contents in the hybrid fabrics were measured by the techniques of inductively coupled plasma atomic emission spectroscopy and UV-vis, and the antibacterial properties of hybrid fabrics were tested by the shake flask and agar diffusion plate method. It is found that the Ag NP coated cotton fabrics exhibit excellent antimicrobial activities against both the Gram-negative bacterium of Escherichia coli (E. coli) and the Gram-positive bacterium of Staphylococcus aureus ( S. aureus). The percentages of reduction bacteria remain at 91.8% and 98.7% for S. aureus and E. coli, respectively, even after 50 cycles of consecutive laundering, which indicates that the antibiotic performance of the as-fabricated hybrid fabrics is also durable.

scholarly journals Optimized Synthesis of FeS Nanoparticles with a High Cr(VI) Removal Capability

2016 ◽  
Vol 2016 ◽  
pp. 1-9 ◽  
Author(s):  
Yuanyuan Liu ◽  
Wenyan Xiao ◽  
Jiajia Wang ◽  
Zakaria A. Mirza ◽  
Tao Wang
Keyword(s):  
Photoelectron Spectroscopy ◽  
Chemical Precipitation ◽  
High Reactivity ◽  
Precipitation Method ◽  
Hydrodynamic Diameter ◽  
X Ray ◽  
Removal Capacity ◽  
Promising Tool ◽  
Horizontal Oscillation ◽  
Average Size

FeS nanoparticles were synthesized using chemical precipitation method involving sulfide and ferrous solutions. Effects of important synthesis parameters including stabilizer, time taken for titration, horizontal oscillation speed, and initial salt concentration on the size of synthesized FeS nanoparticles were investigated by Orthogonal Array design. Increasing the CMC dosage significantly made the hydrodynamic diameter decrease between 0.05 wt.% and 0.15 wt.% while Na2S titration, oscillation rate, and Na2S concentration did not show significant influence on the hydrodynamic diameter of FeS nanoparticles. The synthesized FeS nanoparticles were characterized by using XRD (X-ray diffraction), TEM (transmission electron microscopy), and XPS (X-ray photoelectron spectroscopy). The as-synthesized FeS nanoparticles had an average size of 25 ± 10 nm and had a better long-term stability after storage for 150 days compared to bare FeS particles. Because of the optimized process parameters, the synthesized FeS nanoparticles had a higher Cr(VI) removal capacity of 683 mg per gram of FeS in comparison to the previously reported cases, and up to 92.48% Cr(VI) was removed from aqueous solutions. The small size, special surface property, and high reactivity make the synthesized FeS nanoparticles a promising tool for the remediation of Cr(VI) contaminated soil and groundwater.

scholarly journals Effect of Copper Nanoparticles Dispersion on Catalytic Performance of Cu/SiO2Catalyst for Hydrogenation of Dimethyl Oxalate to Ethylene Glycol

2013 ◽  
Vol 2013 ◽  
pp. 1-6 ◽  
Author(s):  
Yajing Zhang ◽  
Na Zheng ◽  
Kangjun Wang ◽  
Sujuan Zhang ◽  
Jing Wu
Keyword(s):  
Ethylene Glycol ◽  
Copper Nanoparticles ◽  
Photoelectron Spectroscopy ◽  
Sol Gel ◽  
Catalytic Performance ◽  
Bet Surface Area ◽  
X Ray ◽  
Dimethyl Oxalate ◽  
Effect Of Copper ◽  
Average Size

Cu/SiO2catalysts, for the synthesis of ethylene glycol (EG) from hydrogenation of dimethyl oxalate (DMO), were prepared by ammonia-evaporation and sol-gel methods, respectively. The structure, size of copper nanoparticles, copper dispersion, and the surface chemical states were investigated by X-ray diffraction (XRD), transmission electron microscopy (TEM), temperature-programmed reduction (TPR), and X-ray photoelectron spectroscopy (XPS) and N2adsorption. It is found the structures and catalytic performances of the catalysts were highly affected by the preparation method. The catalyst prepared by sol-gel method had smaller average size of copper nanoparticles (about 3-4 nm), better copper dispersion, higher Cu+/C0ratio and larger BET surface area, and higher DMO conversion and EG selectivity under the optimized reaction conditions.

scholarly journals Effect of Annealing, Stoichiometry, and Surface on Magnetism of (Pr,Dy)FeCoB Microparticles Ensemble

2017 ◽  
Vol 62 (3) ◽  
pp. 1923-1930 ◽  
Author(s):  
E.N. Kablov ◽  
O.G. Ospennikova ◽  
E.I. Kunitsyna ◽  
V.P. Piskorskii ◽  
D.V. Korolev ◽  
...  
Keyword(s):  
Thermal Stability ◽  
Magnetic Properties ◽  
Phase Composition ◽  
Photoelectron Spectroscopy ◽  
Surface States ◽  
Anisotropy Field ◽  
X Ray ◽  
Average Size ◽  
Thermal Stability Of ◽  
Effect Of Surface

AbstractMagnetic properties of powder (Pr,Dy)FeCoB ferrimagnetic alloys and effects of annealing, surface states were analyzed. X-ray photoelectron spectroscopy and Mössbauer spectra of powders indicate the effect of surface states on phase composition and magnetic properties of the studied powder, if particles average size is smaller than 10 μm. Effect of stoichiometry on magnetic anisotropy was found. Thermal stability of anisotropy field was proved by replacement of Fe atoms with Co atoms.

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