Direct in situ observation of the electron-driven synthesis of Ag filaments on α-Ag2WO4 crystals

Longo, E.; Cavalcante, L. S.; Volanti, Diogo P.; Gouveia, Amanda Fernandes; Longo, Valeria; Varela, José Arana; Orlandi, Marcelo Ornaghi; Andrés, Juán

doi:10.1038/srep01676

Cited by 109 publications

(150 citation statements)

References 17 publications

(19 reference statements)

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“…The EDS results (Figure 3b,c) confirm that electrondriven structures formed after electron exposure are composed mainly of Ag elements whereas the "pristine" nanoparticle (cube) mainly contains W elements with a smaller quantity Ag as expected. 58 HRTEM analyses of the Ag filament on the α-Ag 2 WO 4 sample after electron irradiation using a TEM microscope also were performed. In Figure 4, an expanded view of the region is depicted and analysis results reveal that the lattice parameter is about 2.3 Å, which is consistent with the (111) plane of the cubic structure of the Ag metallic nanofilament.…”

Section: Resultsmentioning

confidence: 99%

“…56 Kim et al, 16 reported that the gram-positive bacteria S. aureus was less susceptible to AgNPs than gram-negative Escherichia coli. 58 the fascinating real-time in situ electron-driven silver filament growth process from the unstable α-Ag 2 WO 4 crystals matrix using field emission scanning electron microcopy (FE-SEM) and electron irradiation by transmission electron microscopy (TEM). High-resolution TEM (HRTEM) images indicate that these metallic Ag filaments grow on α-Ag 2 WO 4 crystal surfaces.…”

Section: Introductionmentioning

confidence: 99%

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Potentiated Electron Transference in α-Ag₂WO₄ Microcrystals with Ag Nanofilaments as Microbial Agent

et al. 2014

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This study is a framework proposal for understanding the antimicrobacterial effect of both α-Ag 2 WO 4 microcrystals (AWO) synthesized using a microwave hydrothermal (MH) method and α-Ag 2 WO 4 microcrystals with Ag metallic nanofilaments (AWO:Ag) obtained by irradiation employing an electron beam to combat against planktonic cells of methicillin-resistant Staphylococcus aureus (MRSA). These samples were characterized by X-ray diffraction (XRD), FT-Raman spectroscopy, ultraviolet visible (UV−vis) measurements, field emission scanning electron microscopy (FE-SEM), transmission electron microscopy (TEM), and high resolution transmission electron microscopy (HRTEM). The results reveal that both AWO and AWO:Ag solutions have bacteriostatic and bactericidal effects, but the irradiated sample is more efficient; i.e., a 4-fold of the MRSA planktonic cells as compared to the nonirradiated sample was observed. In addition, first principles calculations were performed to obtain structural and electronic properties of AWO and metallic Ag, which provides strong quantitative support for an antimicrobacterial mechanism based on the enhancement of electron transfer processes between α-Ag 2 WO 4 and Ag nanoparticles.

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Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Potentiated Electron Transference in α-Ag₂WO₄ Microcrystals with Ag Nanofilaments as Microbial Agent

et al. 2014

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“…The onedimensional nature observed for the as-prepared nanostructures is related to the preferential growth in the [001] direction. 27,28 Additionally, the a-Ag 2 WO 4 nanorods exhibit other nanoparticles on their surface. Recently, we reported the real-time in situ observation of the silver metallic (Ag) growth process from the unstable a-Ag 2 WO 4 nanorods submitted to electron irradiation from a transmission electron microscope.…”

Section: -33mentioning

confidence: 99%

A novel ozone gas sensor based on one-dimensional (1D) α-Ag₂WO₄ nanostructures

et al. 2014

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aThis paper reports on a new ozone gas sensor based on a-Ag 2 WO 4 nanorod-like structures. Electrical resistance measurements proved the efficiency of a-Ag 2 WO 4 nanorods, which rendered good sensitivity even for a low ozone concentration (80 ppb), a fast response and a short recovery time at 300 C, demonstrating great potential for a variety of applications.Metal semiconducting oxides have drawn the interest of many researchers due to their wide range of applications, especially as gas sensing materials. 1-5 Among them, one-dimensional (1-D) semiconductor nanostructures have been proposed as very interesting materials, especially as gas sensor devices.6-12 It is well known that several technological applications of nanostructured materials are directly related to the morphology, particle size, crystalline phase and activity of specic crystalline planes strictly dependent on synthesis methods. 4,[13][14][15] In particular, the relationship between morphology and gas sensing properties has been well established. 4,16,17Tungsten-based oxides are an important class of materials that display wide potential functional properties, 18-20 speci-cally the silver tungstate (Ag 2 WO 4 ) compound, which can exhibit three different structures: a-orthorhombic, b-hexagonal, and g-cubic.21-25 Recently, our research group reported a detailed study of the synthesis, structural and optical properties of hexagonal nanorod-like elongated a-Ag 2 WO 4 nanocrystals obtained by different methods. 26-28Ozone (O 3 ) is an oxidizing gas used in many technological applications in different areas, such as the food industry, drinking-water treatment, medicine, microelectronic cleaning processes, and others.29,34-39 For example, ozone has been employed as a powerful drinking-water disinfectant and oxidant. 34,35,40 On the other hand, when the ozone level in an atmosphere exceeds a certain threshold value, the exposure to this gas becomes hazardous to human health and can cause serious health problems (e.g. headache, burning eyes, respiratory irritation and lung damage).34,41 The European Guidelines (2002/3/EG) recommend avoiding exposure to ozone levels above 120 ppb.41 Such arguments support the requirement for the determination and continuous monitoring of ozone levels. 3,29,41Gas sensing properties are evaluated in terms of operating temperature, sensitivity, response time, recovery time and stability.29-33 SnO 2 , In 2 O 3 and WO 3 compounds have been considered the most promising ozone gas sensors. 29-33To the best of our knowledge, to date the gas sensing properties of a-Ag 2 WO 4 nanocrystals have never been evaluated.Here, we report the sensing properties of 1-D a-Ag 2 WO 4 nanorod-like structures obtained by the microwave-assisted hydrothermal (MAH) method.42-46 Because of such properties, nanorods are potential candidates for practical applications as ozone gas sensors.The crystalline phase of the as-obtained a-Ag 2 WO 4 sample was analyzed by X-ray diffraction measurement and all reec-tions were indexed to an orthorhombic struc...

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“…33,37,46,47 This investigation's motivation essentially arises from the discovery of an unwanted real-time in situ nucleation and growth of Ag filaments on a-Ag 2 WO 4 crystals which was driven by an accelerated electron beam from an electronic microscope under high vacuum. 48,49 This is the first example of such studies in the scientific literature and it has become a major topic in current research. It is a novel example…”

Section: Introductionmentioning

confidence: 96%

Elucidating the real-time Ag nanoparticle growth on α-Ag₂WO₄during electron beam irradiation: experimental evidence and theoretical insights

Pereira

Andrés

San-Miguel

et al. 2015

Phys. Chem. Chem. Phys.

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Why and how Ag is formed when electron beam irradiation takes place on a-Ag 2 WO 4 in a vacuum transmission electron microscopy chamber? To find an answer, the atomic-scale mechanisms underlying the formation and growth of Ag on a-Ag 2 WO 4 have been investigated by detailed in situ transmission electron microscopy (TEM) and field emission scanning electron microscopy (FE-SEM) studies, density (100) surface, are the most energetically favorable to undergo the diffusion process to form metallic Ag.Ab initio molecular dynamics simulations and the nudged elastic band (NEB) method were used to investigate the minimum energy pathways of these Ag atoms from positions in the first slab layer to outward sites on the (100) surface of a-Ag 2 WO 4 . The results point out that the injection of electrons decreases the activation barrier for this diffusion step and this unusual behavior results from the presence of a lower energy barrier process.

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Direct in situ observation of the electron-driven synthesis of Ag filaments on α-Ag2WO4 crystals

Cited by 109 publications

References 17 publications

Potentiated Electron Transference in α-Ag₂WO₄ Microcrystals with Ag Nanofilaments as Microbial Agent

Potentiated Electron Transference in α-Ag₂WO₄ Microcrystals with Ag Nanofilaments as Microbial Agent

A novel ozone gas sensor based on one-dimensional (1D) α-Ag₂WO₄ nanostructures

Elucidating the real-time Ag nanoparticle growth on α-Ag₂WO₄during electron beam irradiation: experimental evidence and theoretical insights

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Direct in situ observation of the electron-driven synthesis of Ag filaments on α-Ag2WO4 crystals

Cited by 109 publications

References 17 publications

Potentiated Electron Transference in α-Ag2WO4 Microcrystals with Ag Nanofilaments as Microbial Agent

Potentiated Electron Transference in α-Ag2WO4 Microcrystals with Ag Nanofilaments as Microbial Agent

A novel ozone gas sensor based on one-dimensional (1D) α-Ag2WO4 nanostructures

Elucidating the real-time Ag nanoparticle growth on α-Ag2WO4during electron beam irradiation: experimental evidence and theoretical insights

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Potentiated Electron Transference in α-Ag₂WO₄ Microcrystals with Ag Nanofilaments as Microbial Agent

Potentiated Electron Transference in α-Ag₂WO₄ Microcrystals with Ag Nanofilaments as Microbial Agent

A novel ozone gas sensor based on one-dimensional (1D) α-Ag₂WO₄ nanostructures

Elucidating the real-time Ag nanoparticle growth on α-Ag₂WO₄during electron beam irradiation: experimental evidence and theoretical insights