| 1. |
- Datta, Abheek, et al.
(författare)
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Single Nanoparticle Activities in Ensemble : A Study on Pd Cluster Nanoportals for Electrochemical Oxygen Evolution Reaction
- 2019
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Ingår i: The Journal of Physical Chemistry C. - : AMER CHEMICAL SOC. - 1932-7447 .- 1932-7455. ; 123:43, s. 26124-26135
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Tidskriftsartikel (refereegranskat)abstract
- Comprehensive understanding of the electrochemical activity of single nanoparticles (NPs) is in critical need for opening new avenues in the broad field of electrochemistry. Published reports on single-NP electrocatalysts typically include complicated and difficult methods of synthesis and characterization; moreover, these methods usually fail to provide a reliable way to measure the activities of individual NPs within larger ensembles of particles, i.e., in real-life nanocatalyst systems. In the present work, we synthesized from the gas phase Pd NPs that act as nanoportals for electron transfer within surface-oxidized Mg thin films. The physical synthesis method provided excellent control over the deposition density and, hence, enabled the design of a system where each individual open nanoportal forms an independent active single-NP electrode (SNPE). Being uncoupled from one another, these SNPEs contribute separately toward the total electrocatalytic activity while simultaneously providing a measure of their average, individual activities. We were thus able to fabricate a stable, steady-state electrode for the electrochemical oxygen evolution reaction (OER) and to study the activity and stability of the SNPEs over a period of 20 days; the former depended on the size of the NPs, while the latter depended on the SNPEs' resistance to aerial oxidation. The remarkable stability of the ensemble catalysts under OER conditions proves that this concept can be used for further studies on the activities of different single NPs in numerous real-life systems.
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| 2. |
- Ghabboun, Jamal, et al.
(författare)
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Mapping of Embedded Functionalized Carbon Nanotubes in Poly(vinyl alcohol)/Nanotube Composite Using Electrostatic Force Microscopy
- 2012
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Ingår i: IJPAC. International journal of polymer analysis and characterization. - : Taylor & Francis. - 1023-666X .- 1563-5341. ; 17:4, s. 268-277
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Tidskriftsartikel (refereegranskat)abstract
- In the present study, electrostatic force microscopy (EFM) was used as a nondestructive tool for mapping individual functionalized single-wall carbon nanotubes (SWCNTs) incorporated in a poly(vinyl alcohol) (PVA)/CNT composite. The nanocomposite film was prepared using a spin-coating technique. The FT-IR results show esterification between the PVA and the functionalized CNTs. Furthermore, AFM images show that SWCNTs are embedded inside the PVA film. The distribution and orientation of the embedded CNTs were mapped using EFM phase imaging through investigation of the polarizability signal elicited from the CNTs. Results show that polarized SWCNTs are dispersed and oriented in different directions at different depths in the PVA matrix.
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| 3. |
- Singh, Vidyadhar, et al.
(författare)
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Assembly of tantalum porous films with graded oxidation profile from size-selected nanoparticles
- 2014
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Ingår i: Journal of nanoparticle research. - : Springer Science and Business Media LLC. - 1388-0764 .- 1572-896X. ; 16:5
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Tidskriftsartikel (refereegranskat)abstract
- Functionally graded materials offer a way to improve the physical and chemical properties of thin films and coatings for different applications in the nanotechnology and biomedical fields. In this work, design and assembly of nanoporous tantalum films with a graded oxidation profile perpendicular to the substrate surface are reported. These nanoporous films are composed of size-selected, amorphous tantalum nanoparticles, deposited using a gas-aggregated magnetron sputtering system, and oxidized after coalescence, as samples evolve from mono- to multi-layered structures. Molecular dynamics computer simulations shed light on atomistic mechanisms of nanoparticle coalescence, which govern the films porosity. Aberration-corrected (S) TEM, GIXRD, AFM, SEM, and XPS were employed to study the morphology, phase and oxidation profiles of the tantalum nanoparticles, and the resultant films. Design and assembly of tantalum nanoparticle porous films with a graded oxidation profile perpendicular to the substrate surface were fabricated by magnetron-sputter inert-gas aggregation system. At the top-most layers of the film, the larger free-surface areas of nanoparticles enable the formation of thermodynamically stable Ta2O5.
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| 4. |
- Sowwan, Mukhles, et al.
(författare)
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Growth of 2,2-Biimidazole-Based Nanorods on Mica Substrate
- 2010
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Ingår i: Journal of Nanomaterials. - : Hindawi Publishing Corporation. - 1687-4110 .- 1687-4129. ; 2010
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Tidskriftsartikel (refereegranskat)abstract
- The synthesis of a one-dimensional single-stranded helix using the crystallization of silver (I) nitrate and 2,2-biimidazole has promising potential for use in the area of nanotechnology mainly because of its unique electrical properties and its structural similarity to naturally occurring nucleic acids. In this study, we report a new method for the deposition and growth of 2,2-biimidazole- based nanorods on mica substrates by employing a complex solution of silver nitrate (I) and 2,2-biimidazole. The morphology and electrical polarizability of the prepared nanorods are investigated by tapping mode atomic force microscopy (AFM) and noncontact electrostatic force microscopy (EFM). The experimental results show highly polarizable and singly separated nanorods oriented in three preponderant directions. In addition, we show that the active K+ ions on the mica surface are required for the formation of these nanorods. Additionally, these potassium ions are a critical factor in controlling the nucleation and morphology of nanostructures.
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