ORCID Profile
0000-0001-9081-2325
Current Organisation
Pacific Northwest National Laboratory
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Electronic and magnetic properties of condensed matter; superconductivity | Condensed matter physics | Functional materials | Mechanical Engineering | Control Systems, Robotics and Automation | Microelectromechanical Systems (MEMS) | Condensed matter characterisation technique development
Industrial Instruments | Medical Instruments | Expanding Knowledge in Engineering |
Publisher: American Chemical Society (ACS)
Date: 18-03-2010
DOI: 10.1021/JP911099R
Publisher: Elsevier BV
Date: 03-2022
Publisher: Royal Society of Chemistry (RSC)
Date: 2011
DOI: 10.1039/C0NR00689K
Abstract: Fast, sensitive and discriminating detection of hydrogen at room temperature is crucial for storage, transportation, and distribution of hydrogen as an energy source. One dimensional nanowires of SnO2 are potential candidates for improved H2 sensor performance. The single directional conducting continuous nanowires can decrease electrical noise, and their large active surface area could improve the response and recovery time of the sensor. In this work we discuss synthesis and characterization of nanowire arrays made using nanosecond ultraviolet wavelength (266 nm) laser interference processing of ultrathin SnO2 films on SiO2 substrates. The laser energy was chosen to be above the melting point of the films. The results show that the final nanowire formation is dominated by preferential evaporation as compared to thermocapillary flow. The nanowire height (and hence wire aspect ratio) increased with increasing initial film thickness h0 and with increasing laser energy density Eo. Furthermore, a self-limiting effect was observed where-in the wire formation ceased at a specific final remaining thickness of SnO2 that was almost independent of h0 for a given Eo. To understand these effects, finite element modeling of the nanoscale laser heating was performed. This showed that the temperature rise under laser heating was a strong non-monotonic function of film thickness. As a result, the preferential evaporation rate varies as wire formation occurs, eventually leading to a shut-off of evaporation at a characteristic thickness. This results in the stoppage of wire formation. This combination of nanosecond pulsed laser experiments and thermal modeling shows that several unique synthesis approaches can be utilized to control the nanowire characteristics.
Publisher: Royal Society of Chemistry (RSC)
Date: 2011
DOI: 10.1039/C0NR00980F
Abstract: We predict that the presence of extended defects can reduce the mechanical strength of a ceria nanorod by 70%. Conversely, the pristine material can deform near its theoretical strength limit. Specifically, atomistic models of ceria nanorods have been generated with full microstructure, including: growth direction, morphology, surface roughening (steps, edges, corners), point defects, dislocations and grain-boundaries. The models were then used to calculate the mechanical strength as a function of microstructure. Our simulations reveal that the compressive yield strengths of ceria nanorods, ca. 10 nm in diameter and without extended defects, are 46 and 36 GPa for rods oriented along [211] and [110] respectively, which represents almost 10% of the bulk elastic modulus and are associated with yield strains of about 0.09. Tensile yield strengths were calculated to be about 50% lower with associated yield strains of about 0.06. For both nanorods, plastic deformation was found to proceed via slip in the {001} plane with direction --a primary slip system for crystals with the fluorite structure. Dislocation evolution for the nanorod oriented along [110] was nucleated via a cerium vacancy present at the surface. A nanorod oriented along [321] and comprising twin-grain boundaries with {111} interfacial planes was calculated to have a yield strength of about 10 GPa (compression and tension) with the grain boundary providing the vehicle for plastic deformation, which slipped in the plane of the grain boundary, with an associated slip direction. We also predict, using a combination of atomistic simulation and DFT, that rutile-structured ceria is feasible when the crystal is placed under tension. The mechanical properties of nanochains, comprising in idual ceria nanoparticles with oriented attachment and generated using simulated self-assembly, were found to be similar to those of the nanorod with grain-boundary. Images of the atom positions during tension and compression are shown, together with animations, revealing the mechanisms underpinning plastic deformation. For the nanochain, our simulations help further our understanding of how a crystallising ice front can be used to 'sculpt' ceria nanoparticles into nanorods via oriented attachment.
Publisher: American Chemical Society (ACS)
Date: 18-02-2020
Publisher: Wiley
Date: 11-2010
Publisher: Royal Society of Chemistry (RSC)
Date: 2015
DOI: 10.1039/C5RA18450A
Abstract: For the first time, we report a facile strategy for the synthesis of ultra-fine blue-green emitting fluorescent magnesium nanoparticles–protein complex (MgNC) which shows excellent photo stability and also stain cell nuclei with high specificity.
Publisher: Elsevier BV
Date: 03-2018
DOI: 10.1016/J.JCIS.2017.11.064
Abstract: Catalytically active in idual gold (Au) and cerium oxide (CeO
Publisher: Elsevier BV
Date: 2020
DOI: 10.1016/J.SCITOTENV.2019.134133
Abstract: The series of breakthroughs that have occurred within the realm of nanotechnology have been the source of several new products and technological interventions. One of the most salient ex les in this regard is the widespread employment of titanium dioxide (TiO
Publisher: American Chemical Society (ACS)
Date: 14-12-2011
DOI: 10.1021/JP209345W
Publisher: Bentham Science Publishers Ltd.
Date: 17-07-2019
DOI: 10.2174/1389200220666181122124458
Abstract: Biomedical applications of Magnetic Nanoparticles (MNPs) are creating a major impact on disease diagnosis and nanomedicine or a combined platform called theranostics. A significant progress has been made to engineer novel and hybrid MNPs for their multifunctional modalities such as imaging, biosensors, chemotherapeutic or photothermal and antimicrobial agents. MNPs are successfully applied in biomedical applications due to their unique and tunable properties such as superparamagnetism, stability, and biocompatibility. Approval of ferumoxytol (feraheme) for MRI and the fact that several Superparamagnetic Iron Oxide Nanoparticles (SPIONs) are currently undergoing clinical trials have paved a path for future MNPs formulations. Intensive research is being carried out in designing and developing novel nanohybrids for multiple applications in nanomedicine. The objective of the present review is to summarize recent developments of MNPs in imaging modalities like MRI, CT, PET and PA, biosensors and nanomedicine including their role in targeting and drug delivery. Relevant theory and ex les of the use of MNPs in these applications have been cited and discussed to create a thorough understanding of the developments in this field. MNPs have found widespread use as contrast agents in imaging modalities, as tools for bio-sensing, and as therapeutic and theranostics agents. Multiple formulations of MNPs are in clinical testing and may be accepted in clinical settings in near future.
Publisher: Wiley
Date: 15-12-2021
Abstract: Prostate cancer (PCa) is one of the most commonly diagnosed cancers and is the fifth common cause of cancer‐related mortality in men. Current methods for PCa treatment are insufficient owing to the challenges related to the non‐specificity, instability and side effects caused by the drugs and therapy agents. These drawbacks can be mitigated by the design of a suitable drug delivery system that can ensure targeted delivery and minimise side effects. Silica based nanoparticles (SBNPs) have emerged as one of the most versatile materials for drug delivery due to their tunable porosities, high surface area and tremendous capacity to load various sizes and chemistry of drugs. This review gives a brief overview of the diagnosis and current treatment strategies for PCa outlining their existing challenges. It critically analyzes the design, development and application of pure, modified and hybrid SBNPs based drug delivery systems in the treatment of PCa, their advantages and limitations.
Publisher: Springer Science and Business Media LLC
Date: 08-02-2019
DOI: 10.1557/JMR.2018.490
Publisher: Elsevier BV
Date: 11-2010
Publisher: American Scientific Publishers
Date: 07-2006
DOI: 10.1166/JNN.2006.364
Abstract: One dimensional spiral titania nanostructures were obtained by anodization of pure titanium from fluoride containing solutions of phosphoric acid. The formation of nanotubes was found to be dependant on current density. Field Emission Scanning Electron Microscopy (FESEM) shows the diameter of tubes around 70-100 nm which is consistent with the High Resolution Transmission Electron Micrographs (HRTEM) and Atomic Force Microscopy (AFM) images. HRTEM showed the one dimensional growth as spiral in nature which was also supported by AFM images. This anisotropic growth is compared with the possible growth mechanisms.
Publisher: Elsevier BV
Date: 02-2008
Publisher: IEEE
Date: 08-2011
Publisher: American Chemical Society (ACS)
Date: 07-02-2018
Publisher: American Chemical Society (ACS)
Date: 22-11-2010
DOI: 10.1021/NN102246A
Abstract: Ultralight multiwalled carbon nanotube (MWCNT) aerogel is fabricated from a wet gel of well-dispersed pristine MWCNTs. On the basis of a theoretical prediction that increasing interaction potential between CNTs lowers their critical concentration to form an infinite percolation network, poly(3-(trimethoxysilyl) propyl methacrylate) (PTMSPMA) is used to disperse and functionalize MWCNTs where the subsequent hydrolysis and condensation of PTMSPMA introduces strong and permanent chemical bonding between MWCNTs. The interaction is both experimentally and theoretically proven to facilitate the formation of a MWCNT percolation network, which leads to the gelation of MWCNT dispersion at ultralow MWCNT concentration. After removing the liquid component from the MWCNT wet gel, the lightest ever free-standing MWCNT aerogel monolith with a density of 4 mg/cm(3) is obtained. The MWCNT aerogel has an ordered macroporous honeycomb structure with straight and parallel voids in 50-150 μm separated by less than 100 nm thick walls. The entangled MWCNTs generate mesoporous structures on the honeycomb walls, creating aerogels with a surface area of 580 m(2)/g which is much higher than that of pristine MWCNTs (241 m(2)/g). Despite the ultralow density, the MWCNT aerogels have an excellent compression recoverable property as demonstrated by the compression test. The aerogels have an electrical conductivity of 3.2 × 10(-2) S·cm(-1) that can be further increased to 0.67 S·cm(-1) by a high-current pulse method without degrading their structures. The excellent compression recoverable property, hierarchically porous structure with large surface area, and high conductivity grant the MWCNT aerogels exceptional pressure and chemical vapor sensing capabilities.
Publisher: Royal Society of Chemistry
Date: 2019
Publisher: Wiley
Date: 14-10-2020
Abstract: Carbon nitride (CN), a 2D material composed of only carbon (C) and nitrogen (N), which are linked by strong covalent bonds, has been used as a metal-devoid and visible-light-active photocatalyst owing to its magnificent optoelectronic and physicochemical properties including suitable bandgap, adjustable energy-band positions, tailor-made surface functionalities, low cost, metal-free nature, and high thermal, chemical, and mechanical stabilities. CN-based materials possess a lot of advantages over conventional metal-based inorganic photocatalysts including ease of synthesis and processing, versatile functionalization or doping, flexibility for surface engineering, low cost, sustainability, and recyclability without any leaching of toxic metals from photocorrosion. Carbon nitrides and their hybrid materials have emerged as attractive candidates for CO
Publisher: Informa UK Limited
Date: 14-03-2022
Publisher: Wiley
Date: 03-2008
DOI: 10.1002/SIA.2726
Abstract: Nanostructured materials are increasingly subject to nearly every type of chemical and physical analysis possible. Due to their small sizes, there is a significant focus on tools with high spatial resolution. It is also natural to characterize nanomaterials using tools designed to analyze surfaces, because of their high surface area. Regardless of the approach, nanostructured materials present a variety of obstacles to adequate, useful, and needed analysis. Case studies of measurements on ceria and iron metal‐core/oxide‐shell nanoparticles are used to introduce some of the issues that frequently need to be addressed during analysis of nanostructured materials. We use a combination of tools for routine analysis including X‐ray photoelectron spectroscopy (XPS), transmission electron microscopy (TEM), and x‐ray diffraction (XRD) and apply several other methods as needed to obtain essential information. The ex les provide an introduction to other issues and complications associated with the analysis of nanostructured materials including particle stability, probe effects, environmental effects, specimen handling, surface coating, contamination, and time. Copyright © 2008 John Wiley & Sons, Ltd.
Publisher: Elsevier BV
Date: 10-2011
Publisher: Elsevier BV
Date: 10-2019
Publisher: Royal Society of Chemistry (RSC)
Date: 2016
DOI: 10.1039/C6CP00855K
Abstract: Adsorption of trimethylacetic acid on the surface of stoichiometric and oxygen deficient cerium oxide studied using in situ XPS show that the dissociative adsorption is preferred on oxygen deficient cerium oxide (111) surface.
Publisher: Elsevier BV
Date: 2015
DOI: 10.1016/J.CIS.2014.11.004
Abstract: Quantum dots are a group of inorganic nanomaterials exhibiting exceptional optical and electronic properties which impart distinct advantages over traditional fluorescent organic dyes in terms of tunable broad excitation and narrow emission spectra, signal brightness, high quantum yield and photo-stability. Aqueous solubility and surface functionalization are the most common problems for QDs employed in biological research. This review addresses the recent research progress made to improve aqueous solubility, functionalization of biomolecules to QD surface and the poorly understood chemistry involved in the steps of bio-functionalization of such nanoparticles.
Publisher: Springer Science and Business Media LLC
Date: 26-04-2021
Publisher: Royal Society of Chemistry (RSC)
Date: 2020
DOI: 10.1039/D0CS00075B
Abstract: This review highlights the recent progress in porous materials (MOFs, zeolites, POPs, nanoporous carbons, and mesoporous materials) for CO 2 capture and conversion.
Publisher: Elsevier BV
Date: 02-2021
Publisher: Elsevier BV
Date: 03-2022
DOI: 10.1016/J.ENVPOL.2021.118726
Abstract: Engineered nanomaterials (ENMs) are at the forefront of many technological breakthroughs in science and engineering. The extensive use of ENMs in several consumer products has resulted in their release to the aquatic environment. ENMs entering the aquatic ecosystem undergo a dynamic transformation as they interact with organic and inorganic constituents present in aquatic environment, specifically abiotic factors such as NOM and clay minerals, and attain an environmental identity. Thus, a greater understanding of ENM-abiotic factors interactions is required for an improved risk assessment and sustainable management of ENMs contamination in the aquatic environment. This review integrates fundamental aspects of ENMs transformation in aquatic environment as impacted by abiotic factors, and delineates the recent advances in bioavailability and ecotoxicity of ENMs in relation to risk assessment for ENMs-contaminated aquatic ecosystem. It specifically discusses the mechanism of transformation of different ENMs (metals, metal oxides and carbon based nanomaterials) following their interaction with the two most common abiotic factors NOM and clay minerals present within the aquatic ecosystem. The review critically discusses the impact of these mechanisms on the altered ecotoxicity of ENMs including the impact of such transformation at the genomic level. Finally, it identifies the gaps in our current understanding of the role of abiotic factors on the transformation of ENMs and paves the way for the future research areas.
Publisher: Wiley
Date: 03-2020
Publisher: Springer Science and Business Media LLC
Date: 12-2005
Publisher: Springer Science and Business Media LLC
Date: 21-06-2021
Publisher: Wiley
Date: 04-07-2018
DOI: 10.1002/SIA.6490
Publisher: Springer Science and Business Media LLC
Date: 07-2006
Publisher: American Chemical Society (ACS)
Date: 11-11-2013
DOI: 10.1021/JP4068747
Publisher: IOP Publishing
Date: 18-01-2007
DOI: 10.1088/0957-4484/18/7/075303
Abstract: A room temperature, template-free, wet chemical synthesis of ceria nanoparticles and their long term ageing characteristics are reported. High resolution transmission electron microscopy and UV-visible spectroscopy techniques are used to observe the variation in size, structure and oxidation state, respectively as a function of time. The morphology variation and the hierarchical assembly (octahedral superstructure) of nanostructures are imputed to the inherent structural aspects of cerium oxide. It is hypothesized that the 3-5 nm in idual building blocks will undergo an intra-agglomerate re-orientation to attain the low energy configuration. This communication also emphasizes the need for long term ageing studies of nanomaterials in various solvents for multiple functionalities.
Publisher: Elsevier BV
Date: 02-2011
Publisher: The Chemical Society of Japan
Date: 15-04-2021
Publisher: Springer Science and Business Media LLC
Date: 05-09-2007
Publisher: Royal Society of Chemistry (RSC)
Date: 2010
DOI: 10.1039/C0JM01072C
Publisher: Public Library of Science (PLoS)
Date: 26-10-2012
Publisher: Elsevier BV
Date: 06-2011
Publisher: American Chemical Society (ACS)
Date: 08-11-2011
DOI: 10.1021/JZ201243T
Publisher: Wiley
Date: 31-07-2008
Abstract: The formation of nanorods, driven by the physicochemical phenomena during the freezing and after the aging of frozen ceria nanoparticle suspensions, is reported. During freezing of a dilute aqueous solution of CeO2 nanocrystals, some nuclei remain in solution while others are trapped inside micro- and nanometer voids formed within the growing ice front. Over time (2-3 weeks) the particles trapped within the nanometer-wide voids in the ice combine by an oriented attachment process to form ceria nanorods. The experimental observations are consistent with molecular dynamics simulations of particle aggregation in constrained environments. These observations suggest a possible strategy for the templated formation of nanostructures through self-assembly by exploiting natural phenomena, such as voids formed during freezing of water. This research suggests a very simple, green chemical route to guide the formation of one- and three-dimensional self-assembled nanostructures.
Publisher: IOP Publishing
Date: 02-07-2012
Publisher: American Chemical Society (ACS)
Date: 23-05-2007
DOI: 10.1021/JP0700736
Publisher: American Chemical Society (ACS)
Date: 09-11-2016
DOI: 10.1021/ACS.LANGMUIR.6B03022
Abstract: Cerium oxide nanoparticles (CeNPs) have gathered much attention in the biomedical field due to its unique antioxidant property. It can protect cells and tissues from oxidative stress induced damage due to its autoregenerative redox cycle. Our study explores the antioxidant and antigenotoxic behavior of PEGylated CeNPs toward oxidative insult produced by buthionine sulfoximine (BSO) in human keratinocytes (HaCaT cells). BSO inhibits the γ-glutamylcysteinesynthetase (γ-GCS) enzyme and thus acts as a glutathione (GSH) depleting agent to modulate the cellular redox potential. GSH is a natural ROS scavenger present in the mammalian cells, and its depletion causes generation of reactive oxygen species (ROS). In this study, we challenged HaCaT cells (keratinocytes) with BSO to alter the redox potential within the cell and monitored toxicity, ROS generation, and nuclear fragmentation. We also followed changes in expressions of related proteins and genes. We found that PEGylated CeNPs can protect HaCaT cells from BSO-induced oxidative damage. BSO-exposed cells, preincubated with PEGylated CeNPs, showed better cell survival and significant decrease in the intracellular levels of ROS. We also observed decrease in lactate dehydrogenase (LDH) release and nuclear fragmentation in CeNP-treated cells that were challenged with BSO as compared to treatment with BSO alone. Exposure of HaCaT cells with BSO leads to altered expression of antioxidant genes and proteins, i.e., thioredoxin reductase (TrxR) and peroxiredoxin 6 (Prx6) whereas, in our study, pretreatment of PEGylated CeNPs reduces the need for induction of genes that produce enzymes involved in the defense against oxidative stress. Since, growing evidence argued the involvement of ROS in mediating death of mammalian cells in several ailments, our finding reinforces the use of PEGylated CeNPs as a potent pharmacological agent under the lower cellular GSH/GSSG ratios for the treatment of diseases mediated by free radicals.
Publisher: American Chemical Society (ACS)
Date: 19-08-2009
DOI: 10.1021/NN900403H
Publisher: Royal Society of Chemistry (RSC)
Date: 2010
DOI: 10.1039/B922024K
Publisher: Elsevier BV
Date: 07-2007
Publisher: Public Library of Science (PLoS)
Date: 22-02-2011
Publisher: Elsevier BV
Date: 08-2021
Publisher: American Scientific Publishers
Date: 10-2010
Abstract: Doped ceria has been considered for high oxygen ion conductivity for solid oxide fuel cells. In the present study, 20 mole% samarium doped nano ceria powder was prepared by wet chemical synthesis and sintered at different temperatures to retain submicron grains (> 92-96% density). ionic conductivity of the sintered pellets was measured using impedance spectroscopy as a function of temperature (200-800 degrees C). The total maximum conductivity was 1.0 x 10(-2)S.cm(-1) (at 600 degrees C) for s les sintered at 1200 degrees C. The activation energy at higher test temperature decreases with the decrease in the sintering temperature (by 25%). The grain boundary, grain interior conductivity and activation energy of the electrolyte were correlated to the resulting microstructure. It has been demonstrated that use of doped nano ceria powder as precursor not only reduced the sintering temperature but also provided segregation free grain boundary for engineering higher conductivity dense electrolytes.
Publisher: Elsevier BV
Date: 12-2022
Publisher: American Chemical Society (ACS)
Date: 06-2008
DOI: 10.1021/NN800065G
Abstract: Nanomaterials synthesized from nanobuilding blocks promise size-dependent properties, associated with in idual nanoparticles, together with collective properties of ordered arrays. However, one cannot position nanoparticles at specific locations rather innovative ways of coaxing these particles to self-assemble must be devised. Conversely, model nanoparticles can be placed in any desired position, which enables a systematic enumeration of nanostructure from model nanobuilding blocks. This is desirable because a list of chemically feasible hypothetical structures will help guide the design of strategies leading to their synthesis. Moreover, the models can help characterize nanostructure, calculate (predict) properties, or simulate processes. Here, we start to formulate and use a simulation strategy to generate atomistic models of nanomaterials, which can, potentially, be synthesized from nanobuilding block precursors. Clearly, this represents a formidable task because the number of ways nanoparticles can be arranged into a superlattice is infinite. Nevertheless, numerical tools are available to help build nanoparticle arrays in a systematic way. Here, we exploit the "rules of crystallography" and position nanoparticles, rather than atoms, at crystallographic sites. Specifically, we explore nanoparticle arrays with cubic, tetragonal, and hexagonal symmetries together with primitive, face centered cubic and body centered cubic nanoparticle "packing". We also explore binary nanoparticle superlattices. The resulting nanomaterials, spanning CeO(2), Ti-doped CeO(2), ZnO, ZnS, MgO, CaO, SrO, and BaO, comprise framework architectures, with cavities interconnected by channels traversing (zero), one, two and three dimensions. The final, fully atomistic models comprise three hierarchical levels of structural complexity: crystal structure, microstructure (i.e., grain boundaries, dislocations), and superlattice structure.
Publisher: Springer Science and Business Media LLC
Date: 03-2008
Publisher: American Scientific Publishers
Date: 09-2007
DOI: 10.1166/JNN.2007.872
Abstract: Room temperature sensing of hydrogen using randomly oriented tin oxide nanowires has been demonstrated successfully. The role of surface functionalization of nanowires with platinum catalyst in rapid hydrogen detection is also studied. These nanowires were successfully incorporated into a micro-electro-mechanical (MEMS) device. The device can successfully detect hydrogen gas (as low as 500 ppm) with response time as low as 10 sec. Effect of aspect ratio of the nanowires on diffusion of hydrogen molecules in the tin oxide nanowires is elucidated in detail.
Publisher: Wiley
Date: 06-08-2021
Abstract: Research on cerium oxide nanoparticles (nanoceria) has captivated the scientific community due to their unique physical and chemical properties, such as redox activity and oxygen buffering capacity, which made them available for many technical applications, including biomedical applications. The redox mimetic antioxidant properties of nanoceria have been effective in the treatment of many diseases caused by reactive oxygen species (ROS) and reactive nitrogen species. The mechanism of ROS scavenging activity of nanoceria is still elusive, and its redox activity is controversial due to mixed reports in the literature showing pro‐oxidant and antioxidant activity. In light of its current research interest, it is critical to understand the behavior of nanoceria in the biological environment and provide answers to some of the critical and open issues. This review critically analyzes the status of research on the application of nanoceria to treat diseases caused by ROS. It reviews the proposed mechanism of action and shows the effect of surface coatings on its redox activity. It also discusses some of the crucial issues in deciphering the mechanism and redox activity of nanoceria and suggests areas of future research.
Publisher: Royal Society of Chemistry (RSC)
Date: 2018
DOI: 10.1039/C8CC08355J
Abstract: Enzymatic activity of cerium oxide nanoparticles modified by phosphine ligands.
Publisher: American Chemical Society (ACS)
Date: 21-09-2009
DOI: 10.1021/JA9051087
Publisher: American Scientific Publishers
Date: 12-2009
Publisher: IEEE
Date: 08-2012
Publisher: American Vacuum Society
Date: 27-08-2013
DOI: 10.1116/1.4818423
Abstract: This review examines characterization challenges inherently associated with understanding nanomaterials and the roles surface and interface characterization methods can play in meeting some of the challenges. In parts of the research community, there is growing recognition that studies and published reports on the properties and behaviors of nanomaterials often have reported inadequate or incomplete characterization. As a consequence, the true value of the data in these reports is, at best, uncertain. With the increasing importance of nanomaterials in fundamental research and technological applications,it is desirable that researchers from the wide variety of disciplines involved recognize the nature of these often unexpected challenges associated with reproducible synthesis and characterization of nanomaterials, including the difficulties of maintaining desired materials properties during handling and processing due to their dynamic nature. It is equally valuable for researchers to understand how characterization approaches (surface and otherwise) can help to minimize synthesis surprises and to determine how (and how quickly) materials and properties change in different environments. Appropriate application of traditional surface sensitive analysis methods (including x-ray photoelectron and Auger electron spectroscopies, scanning probe microscopy, and secondary ion mass spectroscopy) can provide information that helps address several of the analysis needs. In many circumstances, extensions of traditional data analysis can provide considerably more information than normally obtained from the data collected. Less common or evolving methods with surface selectivity (e.g., some variations of nuclear magnetic resonance, sum frequency generation, and low and medium energy ion scattering) can provide information about surfaces or interfaces in working environments (operando or in situ) or information not provided by more traditional methods. Although these methods may require instrumentation or expertise not generally available, they can be particularly useful in addressing specific questions, and ex les of their use in nanomaterial research are presented.
Publisher: American Chemical Society (ACS)
Date: 22-06-2012
DOI: 10.1021/JP300725S
Publisher: IEEE
Date: 08-2011
Publisher: American Chemical Society (ACS)
Date: 16-05-2012
DOI: 10.1021/NN301316J
Abstract: Semiconductor nanoparticles conjugated with organic- and dye-molecules to yield high efficiency visible photoluminescence (PL) hold great potential for many future technological applications. We show that folic acid (FA)-conjugated to nanosize TiO(2) and CeO(2) particles demonstrates a dramatic increase of photoemission intensity at wavelengths between 500 and 700 nm when derivatized using aminopropyl trimethoxysilane (APTMS) as spacer-linker molecules between the metal oxide and FA. Using density-functional theory (DFT) and time-dependent DFT calculations we demonstrate that the strong increase of the PL can be explained by electronic transitions between the titania surface oxygen vacancy (OV) states and the low-energy excited states of the FA/APTMS molecule anchored onto the surface oxygen bridge sites in close proximity to the OVs. We suggest this scenario to be a universal feature for a wide class of metal oxide nanoparticles, including nanoceria, possessing a similar band gap (∼3 eV) and with a large surface-vacancy-related density of electronic states. We demonstrate that the molecule-nanoparticle linker can play a crucial role in tuning the electronic and optical properties of nanosystems by bringing optically active parts of the molecule and of the surface close to each other.
Publisher: Elsevier BV
Date: 02-2010
Publisher: Elsevier BV
Date: 09-2020
Publisher: American Chemical Society (ACS)
Date: 14-08-2009
DOI: 10.1021/LA901298Q
Abstract: Enhancing the optical emission of cerium oxide nanoparticles is essential for potential biomedical applications. In the present work, we report a simple chemical precipitation technique to synthesize europium-doped cerium oxide nanostructures to enhance the emission properties. Structural and optical properties showed an acute dependence on the concentration of oxygen ion vacancy and trivalent cerium, which, in turn, could be modified by dopant concentration and the annealing temperature. Results from X-ray photoelectron spectroscopy showed an increase in tetravalent cerium concentration to 85% on annealing at 900 degrees C. The concentration of oxygen ion vacancy increased from 1.7x10(20) cm(-3) to 4.1x10(20) cm(-3) with the increase in dopant concentration. Maximum emission at room temperature was obtained for 15 mol % Eu-doped ceria, which improved with annealing temperature. The role of oxygen ion vacancies and trivalent cerium in modifying the emission properties is discussed.
Publisher: Elsevier BV
Date: 06-2022
Publisher: Elsevier BV
Date: 06-2008
Publisher: Informa UK Limited
Date: 20-07-2022
Publisher: American Chemical Society (ACS)
Date: 19-08-2020
Publisher: American Vacuum Society
Date: 2022
DOI: 10.1116/6.0001460
Abstract: An in-depth understanding of charge transfer processes at the electrochemical interfaces is a critical knowledge gap impeding the design of energy storage materials. X-ray photoelectron spectroscopy plays an important role in analyzing electronic structures of heterogeneous interfaces, such as electrode-electrolyte interphases. Correspondingly, ex situ studies based on postmortem analysis of electrode materials using x-ray techniques are widely reported in the literature but often fail to capture intermediate and transient species, which are critical for a predictive understanding of the charge transfer process. The lack of extensive in situ/operando x-ray analysis of buried interfaces in energy storage systems can be mainly attributed to technical limitations, such as the requirement of high vacuum conditions. However, in the past decade, considerable efforts have been devoted to overcoming these technical barriers and enable investigation of the solid/solid and solid/liquid interfaces. This review catalogs some of the recent progresses and new experimental designs in the application of in situ and operando x-ray photoelectron spectroscopy toward characterizing interfacial processes and emergent properties, which can help build the design strategy for advanced batteries. The remaining challenges and future research directions are also discussed, as potential paths forward in this field.
Publisher: American Chemical Society (ACS)
Date: 05-02-2010
DOI: 10.1021/LA904285G
Publisher: Elsevier BV
Date: 05-2020
Publisher: Wiley
Date: 21-08-2021
Abstract: Mesoporous carbon nitrides with C 3 N 5 and C 3 N 6 stoichiometries created a new momentum in the field of organic metal‐free semiconductors owing to their unique band structures and high basicity. Here, we report on the preparation of a novel graphitic microporous carbon nitride with a tetrazine based chemical structure and the composition of C 3 N 5.4 using ultra‐stable Y zeolite as the template and aminoguanidine hydrochloride, a high nitrogen‐containing molecule, as the CN precursor. Spectroscopic characterization and density functional theory calculations reveal that the prepared material exhibits a new molecular structure, which comprises two tetrazines and one triazine rings in the unit cell and is thermodynamically stable. The resultant carbon nitride shows an outstanding surface area of 130.4 m 2 g −1 and demonstrates excellent CO 2 adsorption per unit surface area of 47.54 μmol m −2 , which is due to the existence of abundant free NH 2 groups, basic sites and microporosity. The material also exhibits highly selective sensing over water molecules (151.1 mmol g −1 ) and aliphatic hydrocarbons due to its unique microporous structure with a high amount of hydrophilic nitrogen moieties and recognizing ability towards small molecules.
Publisher: Royal Society of Chemistry (RSC)
Date: 2010
DOI: 10.1039/C0MB00014K
Publisher: No publisher found
Date: 2020
Publisher: Wiley
Date: 27-01-2011
Abstract: Application of inorganic nanoparticles in diagnosis and therapy has become a critical component in the targeted treatment of diseases. The surface modification of inorganic oxides is important for providing ersity in size, shape, solubility, long-term stability, and attachment of selective functional groups. This Minireview describes the role of polyethylene glycol (PEG) in the surface modification of oxides and focuses on their biomedical applications. Such a PEGylation of surfaces provides "stealth" characteristics to nanomaterials otherwise identified as foreign materials by human body. The role of PEG as structure-directing agent in synthesis of oxides is also presented.
Publisher: Royal Society of Chemistry (RSC)
Date: 2015
DOI: 10.1039/C4CP04961F
Abstract: Experimental and theoretical investigations were performed to investigate the effect of water on optical properties of nanoceria as a function of Ce 3+ concentration.
Publisher: Royal Society of Chemistry (RSC)
Date: 2013
DOI: 10.1039/C3TB20204F
Publisher: Springer Science and Business Media LLC
Date: 22-09-2017
Publisher: Informa UK Limited
Date: 07-05-2022
Publisher: Royal Society of Chemistry (RSC)
Date: 2022
DOI: 10.1039/D2TB01135B
Abstract: Nanoceria prepared with different Ce 3+ /Ce 4+ ratios show different oxidase mimetic activities. The activity is enhanced selectively in presence of fluoride ions and used for glutathione detection.
Publisher: Royal Society of Chemistry (RSC)
Date: 2010
DOI: 10.1039/B919677N
Abstract: Reactive oxygen and nitrogen species play a critical role in many degenerative diseases and in aging. Nanomaterials, especially modified fullerenes and cerium oxide nanoparticles, have been shown to effectively protect mammalian cells against damage caused by increased reactive oxygen or nitrogen species, likely through their direct reaction with superoxide radical, since each of these materials has been shown to act as effective superoxide dismutase mimetics in vitro. This critical review discusses the chemistry of these nanomaterials and the context in which their radical scavenging activities have been studied in biological model systems. Current studies are focused on determining the uptake, metabolism, distribution, toxicity and fate of these nanomaterials in cell and animal model systems. Ultimately if shown to be safe, these nanomaterials have the potential to be used to reduce the damaging effects of radicals in biological systems (101 references).
Publisher: Elsevier BV
Date: 05-2017
DOI: 10.1016/J.COLSURFB.2017.02.004
Abstract: Fe
Publisher: Wiley
Date: 18-04-2012
DOI: 10.1002/SIA.5006
Publisher: Elsevier BV
Date: 12-2019
DOI: 10.1016/J.ENVPOL.2019.113313
Abstract: Copper oxide nanoparticles (CuO NPs) is one of the most commonly used metal oxide nanoparticles for commercial and industrial products. An increase in the manufacturing and use of the CuO NPs based products has increased the likelihood of their release into the aquatic environment. This has attracted major attention among researchers to explore their impact in human as well as environmental systems. CuO NPs, once released into the environment interact with the biotic and abiotic constituents of the ecosystem. Hence the objective of the study was to provide a holistic understanding of the effect of abiotic factors on the stability and aggregation of CuO NPs and its correlation with their effect on the development of zebrafish embryo. It has been observed that the bioavailability of CuO NPs decrease in presence of humic acid (HA) and heteroagglomeration of CuO NPs occurs with clay minerals. CuO NPs, CuO NPs + HA and CuO NPs + Clay significantly altered the expression of genes involved in development of dorsoventral axis and neural network of zebrafish embryos. However, the presence of HA with clay showed protective effect on zebrafish embryo development. These findings provide new insights into the interaction of NPs with abiotic factors and combined effects of such complexes on developing zebrafish embryos genetic markers.
Publisher: Springer Science and Business Media LLC
Date: 06-06-2014
DOI: 10.1038/CDD.2014.72
Publisher: Elsevier BV
Date: 10-2015
DOI: 10.1016/J.JCIS.2015.06.015
Abstract: Gold nanoparticles (AuNPs) are known to possess intrinsic biological peroxidase-like activity that has applications in development of numerous biosensors. The reactivity of the Au atoms at the surface of AuNPs is critical to the performance of such biosensors, yet little is known about the effect of biomolecules and ions on the peroxidase-like activity. In this work, the effect of ATP and other biologically relevant molecules and ions over peroxidase-like activity of AuNPs are described. Contrary to the expectation that nanoparticles exposed to biomolecules may lose the catalytic property, ATP and ADP addition enhanced the peroxidase-like activity of AuNPs. The catalytic activity was unaltered by the addition of free phosphate, sulphate and carbonate anions however, addition of ascorbic acid to the reaction mixture diminished the intrinsic peroxidase-like activity of AuNPs, even in the presence of ATP and ADP. In contrast to AuNPs, ATP did not synergize and improve the peroxidase activity of the natural peroxidase enzyme, horseradish peroxidase.
Publisher: American Chemical Society (ACS)
Date: 04-02-2009
DOI: 10.1021/CG801358Z
Publisher: Elsevier BV
Date: 09-2019
Publisher: American Chemical Society (ACS)
Date: 30-10-2007
DOI: 10.1021/JP076164K
Publisher: Elsevier BV
Date: 08-2022
Location: United States of America
Start Date: 07-2023
End Date: 07-2024
Amount: $1,310,536.00
Funder: Australian Research Council
View Funded ActivityStart Date: 10-2021
End Date: 10-2023
Amount: $183,437.00
Funder: Australian Research Council
View Funded Activity