ORCID Profile
0000-0001-5852-0808
Current Organisations
KU Leuven
,
University of Dublin Trinity College
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Publisher: IOP Publishing
Date: 03-05-2012
DOI: 10.1088/0957-4484/23/21/215601
Abstract: Boron nitride nanotube (BNNT) films were grown on silicon/silicon dioxide (Si/SiO(2)) substrates by a catalytic chemical vapor deposition (CVD) method in a horizontal electric furnace. The effects of growth temperature and catalyst concentration on the morphology of the films and the structure of in idual BNNTs were systematically investigated. The BNNT films grown at 1200 and 1300 °C consisted of a homogeneous dispersion of separate tubes in random directions with average outer diameters of ~30 and ~60 nm, respectively. Meanwhile, the films grown at 1400 °C comprised of BNNT bundles in a flower-like morphology, which included thick tubes with average diameters of ~100 nm surrounded by very thin ones with diameters down to ~10 nm. In addition, low catalyst concentration led to the formation of BNNT films composed of entangled curly tubes, while high catalyst content resulted in very thick tubes with diameters up to ~350 nm in a semierect flower-like morphology. Extensive transmission electron microscopy (TEM) investigations revealed the diameter-dependent growth mechanisms for BNNTs namely, thin and thick tubes with closed ends grew by base-growth and tip-growth mechanisms, respectively. However, high catalyst concentration motivated the formation of filled-with-catalyst BNNTs, which grew open-ended with a base-growth mechanism.
Publisher: American Chemical Society (ACS)
Date: 16-04-2014
DOI: 10.1021/NN501306Y
Abstract: Simple preparation methods of chemically versatile and highly functionalizable surfaces remain rare and present a challenging research objective. Here, we demonstrate a simultaneous electropolymerization and electro-click functionalization process (SEEC) for one-pot self-construction of aniline- and naphthalene-based functional polymer films where both polymerization and click functionalization are triggered by applying electrochemical stimuli. Cyclic voltammetry (CV) can be applied for the simultaneous oxidation of 4-azidoaniline and the reduction of Cu(II) ions, resulting in polymerization of the former, and the Cu(I)-catalyzed alkyne/azide cycloaddition ("click" chemistry). Properties of the films obtained can be tuned by varying their morphology, their chemically "clicked" content, or by postconstruction functionalization. To demonstrate this, the CV scan rates, component monomers, and "clicked" molecules were varied. Covalent postconstruction immobilization of horseradish peroxidase was also performed. Consequently, pseudocapacitance and enzyme activity were affected. SEEC provides surface scientists an easy access to a wide range of functionalization possibilities in several fields including sensors, fuel cells, photovoltaics, and biomaterials.
Publisher: Elsevier BV
Date: 12-2022
Publisher: Royal Society of Chemistry (RSC)
Date: 2012
DOI: 10.1039/C2JM15109J
Publisher: Wiley
Date: 03-04-2014
Publisher: Royal Society of Chemistry (RSC)
Date: 2014
DOI: 10.1039/C3CS60260E
Abstract: Recent years have witnessed many breakthroughs in research on two-dimensional (2D) nanomaterials, among which is hexagonal boron nitride (h-BN), a layered material with a regular network of BN hexagons. This review provides an insight into the marvellous nano BN flatland, beginning with a concise introduction to BN and its low-dimensional nanostructures, followed by an overview of the past and current state of research on 2D BN nanostructures. A comprehensive review of the structural characteristics and synthetic routes of BN monolayers, multilayers, nanomeshes, nanowaves, nanoflakes, nanosheets and nanoribbons is presented. In addition, electronic, optical, thermal, mechanical, magnetic, piezoelectric, catalytic, ecological, biological and wetting properties, applications and research perspectives for these novel 2D nanomaterials are discussed.
Publisher: Royal Society of Chemistry (RSC)
Date: 2016
DOI: 10.1039/C6TA03311C
Abstract: All polymeric yolk–shell nanocapsules offer tunable platforms for nanostructured catalyst design including hierarchical architectures, allowing the on-demand synthesis of catalysts.
Publisher: IEEE
Date: 04-2015
Publisher: Elsevier BV
Date: 06-2012
Publisher: Springer Science and Business Media LLC
Date: 30-11-2012
Publisher: Springer Science and Business Media LLC
Date: 02-01-2013
Abstract: Multiwalled boron nitride nanotubes (BNNTs) have very attractive mechanical and thermal properties, e.g., elasticity, tensile strength, and high resistance to oxidation, and may be considered as ideal reinforcing agents in lightweight metal matrix composites. Herein, for the first time, Al-BNNT ribbons with various BNNT contents (up to 3 wt.%) were fabricated via melt spinning in an argon atmosphere. BNNTs were randomly dispersed within a microcrystalline Al matrix under ribbon casting and led to more than doubling of room-temperature ultimate tensile strength of the composites compared to pure Al ribbons produced at the similar conditions.
Publisher: American Chemical Society (ACS)
Date: 13-07-2021
Publisher: American Chemical Society (ACS)
Date: 22-07-2011
DOI: 10.1021/NN201838W
Abstract: The growth, structure, and properties of two-dimensional boron nitride (BN) nanostructures synthesized by a thermal chemical vapor deposition method have been systematically investigated. Most of the BN nanosheets (BNNSs) were less than 5 nm in thickness, and their purity was confirmed by X-ray energy dispersive spectroscopy, X-ray photoelectron spectroscopy, electron energy loss spectroscopy, and Raman spectroscopy. The effects of the process variables on the morphology and roughness of the coatings were studied using atomic force microscopy and scanning electron microscopy. A smooth BN coating was obtained at 900 °C, while compact BNNS coatings composed of partially vertically aligned nanosheets could be achieved at 1000 °C and higher temperatures. These nanosheets were mostly separated and exhibited high surface area especially at higher synthesis temperatures. The nonwetting properties of the BNNS coatings were independent of the water pH and were examined by contact angle goniometry. The present results enable a convenient growth of pure BNNS coatings with controllable levels of water repellency, ranging from partial hydrophilicity to superhydrophobicity with contact angles exceeding 150°.
Publisher: American Chemical Society (ACS)
Date: 16-12-2016
Abstract: Construction of cellular architectures has been expected to enhance materials' mechanical tolerance and to stimulate and broaden their efficient utilizations in many potential fields. However, hitherto, there have been rather scarce developments in boron nitride (BN)-type cellular architectures because of well-known difficulties in the syntheses of BN-based structures. Herein, cellular-network multifunctional foams made of interconnective nanotubular hexagonal BN (h-BN) architectures are developed using carbothermal reduction-assisted in situ chemical vapor deposition conversion from N-doped tubular graphitic cellular foams. These ultralight, chemically inert, thermally stable, and robust-integrity (supporting about 25,000 times of their own weight) three-dimensional-BN foams exhibit a 98.5% porosity, remarkable shape recovery (even after cycling compressions with 90% deformations), excellent resistance to water intrusion, thermal diffusion stability, and high strength and stiffness. They remarkably reduce the coefficient of thermal expansion and dielectric constant of polymeric poly(methyl methacrylate) composites, greatly contribute to their thermal conductivity improvement, and effectively limit polymeric composite softening at elevated temperatures. The foams also demonstrate high-capacity adsorption-separation and removal ability for a wide range of oils and organic chemicals in oil/water systems and reliable recovery under their cycling usage as organic adsorbers. These created multifunctional foams should be valuable in many high-end practical applications.
Publisher: Thomas Telford Ltd.
Date: 03-2013
DOI: 10.1680/SI.12.00007
Abstract: This study begins with a brief discussion on the high-temperature chemical vapor deposition synthesis of transparent boron nitride nanosheet films on silicon/silicon dioxide substrates. The compact nanosheets grew perpendicular to the substrate surface, and the majority of them had thicknesses of less than 5 nm. Ultraviolet-visible spectroscopy measurements demonstrated a wide optical band gap of ∼5·6 eV of nanosheets, and cathodoluminescence spectroscopy showed their strong luminescence emission in the ultraviolet region. The nanorough surface morphology of the films induced nonwetting and self-cleaning features with water-contact angles reaching ∼153°. Such transparent superhydrophobic films can be utilized for the preparation of nonwetting ultraviolet light-emitting surfaces for optoelectronics applications, antifouling surfaces on marine vessels or oil–water separation equipments.
Publisher: IEEE
Date: 08-2012
Publisher: Royal Society of Chemistry (RSC)
Date: 2015
DOI: 10.1039/C5TA08134C
Abstract: New boron nitride porous monoliths with high efficiency and excellent adsorption applications were successfully fabricated by a brand-new and template-free method.
Publisher: American Chemical Society (ACS)
Date: 17-04-2013
DOI: 10.1021/LA4004356
Abstract: Designing geometrical structures is an effective route to tailoring the wettability of a surface. BN-based hierarchical nano- and microstructures, in particular, vertically aligned and randomly distributed tubes and cones, were synthesized and employed as a platform for studying the influence of surface morphology on their static and dynamic interactions with water droplets. The variation of the contact angle in different hierarchical BN films is attributed to the combined effects of surface roughness and partial liquid-solid contact at the interface. Moreover, the impact response of water droplets impinging on BN arrays with different wetting properties is distinct. In the case of superhydrophobic films, the water droplet bounces off the surface several times whereas in less hydrophobic films it does not rebound and remains pinned to the surface. These results provide a facile route for the selective preparation of hierarchical BN nanostructure array films and a better understanding of their tunable water-repelling behavior, for which a number of promising applications in microelectronics and optics can be envisaged.
Publisher: Wiley
Date: 11-02-2022
DOI: 10.1111/GCB.16060
Abstract: Research in global change ecology relies heavily on global climatic grids derived from estimates of air temperature in open areas at around 2 m above the ground. These climatic grids do not reflect conditions below vegetation canopies and near the ground surface, where critical ecosystem functions occur and most terrestrial species reside. Here, we provide global maps of soil temperature and bioclimatic variables at a 1-km
Publisher: American Chemical Society (ACS)
Date: 09-10-2014
DOI: 10.1021/NN5041729
Abstract: Today many aspects of science and technology are progressing into the nanoscale realm where surfaces and interfaces are intrinsically important in determining properties and performances of materials and devices. One familiar phenomenon in which interfacial interactions play a major role is the wetting of solids. In this work we use a facile one-step plasma method to control the wettability of boron nitride (BN) nanostructure films via covalent chemical functionalization, while their surface morphology remains intact. By tailoring the concentration of grafted hydroxyl groups, superhydrophilic, hydrophilic, and hydrophobic patterns are created on the initially superhydrophobic BN nanosheet and nanotube films. Moreover, by introducing a gradient of the functional groups, directional liquid spreading toward increasing [OH] content is achieved on the films. The resulting insights are meant to illustrate great potentials of this method to tailor wettability of ceramic films, control liquid flow patterns for engineering applications such as microfluidics and biosensing, and improve the interfacial contact and adhesion in nanocomposite materials.
Publisher: IOP Publishing
Date: 20-07-2012
DOI: 10.1088/0953-8984/24/31/314205
Abstract: An improved 'chemical blowing' route presuming atmospheric-pressure pre-treatment and moderate heating rate of designated precursors was developed to synthesize ultra-thin boron nitride (BN) nanosheets with high yield and large lateral dimensions. The yield reached as high as 40 wt% with respect to raw materials (ammonia borane). The strong oxygen-related ultraviolet luminescence together with a blue emission of these BN nanosheets was then documented and analyzed. This implies potential applications in solid-state lighting, ultraviolet lasing and full-color luminescence. Mechanical strength of different polymeric composites with a small fraction of BN nanosheet fillers was dramatically increased by tens of per cent, while high transparency of composite materials was still maintained in the visible optical range. The increased yield and reduced cost of BN nanosheets should promote their wide practical applications in various composites.
Publisher: Elsevier BV
Date: 02-2013
No related grants have been discovered for Amir Pakdel.