Scott Holdren

Johns Hopkins University Applied Physics Laboratory

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Michael R. Zachariah

University of California, Riverside

Bryan W. Eichhorn

University of Maryland, College Park

Tao Wu

Laboratoire d'Analyse et d'Architecture des Systèmes

Yong Yang

Institute of New Materials

Kenan P. Fears

United States Naval Research Laboratory

Haiyang Wang

Xi'an Jiaotong University

Maija M. Kuklja

University of Maryland, College Park

Jeffrey C. Owrutsky

United States Naval Research Laboratory

Xizheng Wang

Tianjin University of Traditional Chinese Medicine

Roman Tsyshevsky

University of Maryland, College Park

Cooperative Institutions

University of Maryland, College Park

Park University

Lawrence Berkeley National Laboratory

Johns Hopkins University

Chinese Academy of Sciences

University of California, Riverside

Lund University

Berkeley College

Johns Hopkins University Applied Physics Laboratory

United States Naval Research Laboratory

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Quantitative determination of calcium, magnesium, and zinc in fingernails by laser-induced breakdown spectroscopy

Talanta (2013)

David A. Rusak Ann E. Zeleniak Jillian L. Obuhosky Scott Holdren Craig A. Noldy

Laser-induced breakdown spectroscopy

10.1016/j.talanta.2013.08.022

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Citations (25)

Vapor-Phase Strategy to Pillaring of Two-Dimensional Zeolite

Journal of the American Chemical Society (2019)

Lu Wei Kechen Song Wei Wu Scott Holdren Guanghui Zhu

Two-dimensional (2D) layered zeolites are new forms of 3D zeolite frameworks. They can be pillared to form more open porous structures with increased access for reactants that are too big for the micropores of zeolites. The current pillaring procedure, however, requires intercalation of pillaring precursors by dispersing 2D zeolite in an alkoxide liquid and hydrolizing entrapped alkoxide to form inorganic oxide pillars in an aqueous alkaline solution. Both steps use excess solvents, generate significant waste, and require multiple synthesis and separation steps. Here we report a vapor-phase pillarization (VPP) process to produce pillared zeolites from 2D layered zeolite structures. The VPP process has ∼100% efficiency of alkoxide usage in the intercalation step, requires less (and, in some cases, zero) water addition in the hydrolysis step, does not require separation for product recovery, and generates no liquid waste. Furthermore, synthesis of pillared zeolites via the VPP process can be accomplished within a single apparatus with one-time operation. The pillared zeolite prepared by the VPP method preserved the zeolitic layered structure as well as acidity and showed enhancement in catalytic alkylation of mesitylene with benzyl alcohol compared to 2D layered zeolite without pillarization treatment.

Alkoxide

Mesitylene

Benzyl alcohol

10.1021/jacs.9b03479

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Citations (27)

Rapid Carbothermal Shock Enhances the Double-Layer Response of Graphene Oxide–Carbon Nanotube Electrodes

Energy & Fuels (2021)

Jesse S. Ko Po Yu Meng Hadas Elazar-Mittelman James K. Johnson Zhiyong Xia

Graphene oxide and carbon nanotube composites are considered to be an ideal electrode for electrochemical energy storage and conversion. Herein, we prepare electrodes via a green synthesis that yields a binderless, flexible, and free-standing electrode. To improve the performance of these electrodes comprising graphene oxide and carbon nanotubes (GO–CNT), we carry out carbothermal shock (CTS), which reduces graphene oxide in a rapid (millisecond time scale) and tunable manner (1000–2000 K). When CTS is employed, the specific capacitance of GO–CNT increases by 50%, from 30 to 45 F g–1, for reduced GO–CNT (GO–CNT_CTS). When benchmarking against activated carbon, both GO–CNT and GO–CNT_CTS outperform in terms of capacitance and rate capability. We then examine impedance spectroscopy data in the form of two-dimensional color-mapped surface plots to analyze the dependence of the real and imaginary capacitance and the phase angle as a function of both frequency and potential. This analysis provides key mechanistic insight into the electrochemical double-layer response, such as the characteristic relaxation time and charge-transfer resistance. This analysis shows that, upon CTS, the relaxation times of GO–CNT-based electrodes are 70% faster than that of activated carbon and charge-transfer resistances are reduced dramatically.

Double-layer capacitance

10.1021/acs.energyfuels.1c02450

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Citations (6)

Corrigendum to “Carbon addition lowers initiation and iodine release temperatures from iodine oxide-based biocidal energetic materials” [Carbon 130 (2018) 410–415]

Carbon (2019)

Tao Wu Xizheng Wang Jeffery B. DeLisio Scott Holdren Michael R. Zachariah

Carbon fibers

10.1016/j.carbon.2018.02.096

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Citations (0)

Combustion of 3D printed 90 wt% loading reinforced nanothermite

Combustion and Flame (2020)

Jin Shen Haiyang Wang Dylan J. Kline Yong Yang Xizheng Wang

Polystyrene

Polypropylene

10.1016/j.combustflame.2020.01.021

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Citations (46)

Ignition of Nanoscale Titanium/Potassium Perchlorate Pyrotechnic Powder: Reaction Mechanism Study

The Journal of Physical Chemistry C (2018)

Miles C. Rehwoldt Yong Yang Haiyang Wang Scott Holdren Michael R. Zachariah

The reaction mechanism and ignition characteristics of the pyrotechnic composite of titanium nanoparticles and micron-sized potassium perchlorate was investigated under rapid heating conditions (∼5 × 105 K/s) by temperature jump (T-Jump) time-of-flight mass spectrometry. X-ray photoelectron spectroscopy surface analysis and transmission electron microscopy (TEM) characterization of titanium nanoparticles show a reactive oxide layer (∼6 nm) composed of amorphous TiO2 and roughly 20% crystalline TiN and titanium oxynitride. The T-Jump and thermogravimetric analysis reveals the oxide layer to be responsible for catalysis of oxygen release from KClO4, resulting in ignition temperatures as low as 720 K in atmospheric pressure argon. Fast and slow in situ heating TEM corroborate the findings of oxygen atmosphere ignition characteristics, which illustrate KClO4 melting and coating of titanium nanoparticles immediately before oxidizer decomposition and titanium oxidation. Unlike aluminum, which has been shown to have a rapid loss of surface area before combustion as a result of sintering, Ti retained its high surface area. A combination of a reactive shell and the preservation of titanium nanostructure under rapid heating may lead to enhanced oxygen diffusion and increased potential for transient energy release.

Thermogravimetric analysis

Titanium oxide

10.1021/acs.jpcc.8b03164

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Citations (38)

Fixed Feed Temperature-Programmed Modulation—A Quantitative Method To Obtain Thermophysical Parameters: Application to Chemical Warfare Agent Adsorbents

The Journal of Physical Chemistry C (2019)

William T. Gibbons Scott Holdren Junkai Hu Bryan W. Eichhorn Michael R. Zachariah

Assessing the interaction between an adsorbate and a surface is essential for optimal engineering and design of adsorbents. For low-vapor-pressure adsorbates, which also exhibit relatively weak adsorption behavior (physisorption), both the sample and the system (manifolding, reactor, etc.) demonstrate similar affinities for the probe molecule. To minimize errors, researchers often use large sample masses, which are not often convenient to obtain, particularly for new lab-generated materials. To circumvent this issue, we demonstrate an approach where we fix the thermodynamic state of the system, and then thermally perturb a small sample under fixed feed conditions, thus eliminating the impact of the system response. By varying the thermal modulation rate, various regimes for analyzing adsorption, desorption, and reactions are possible, which enables the extraction of thermophyiscal parameters. In this paper, we first validate the fixed feed temperature-programmed modulation (FFTPM) method against a common adsorbate/adsorbent (methanol/BPL carbon) and then extend the technique to dimethyl methyl phosphonate (DMMP)/carbon systems. We demonstrate the utility of such an approach for quantitatively assessing adsorption capacities, differential heats of adsorption, isosteric heats of adsorption, and adsorption kinetics parameter estimation for DMMP on carbon adsorbents. The FFTPM method is well-suited for rapidly screening and characterizing adsorbents, reactive sorbents, and other systems which exhibit physisorption phenomena.

Physisorption

Carbon fibers

10.1021/acs.jpcc.8b08991

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Citations (2)

Spectroscopic and Computational Studies of Room-Temperature Decomposition of a Chemical Warfare Agent Simulant on Copper Oxide

Lena Trotochaud Roman Tsyshevsky Scott Holdren Kenan P. Fears Ashley R. Head

Copper oxide

Source

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Ultrafast, scalable laser photothermal synthesis and writing of uniformly dispersed metal nanoclusters in polymer films

Nanoscale (2019)

Pankaj Ghildiyal Yong Yang Dylan J. Kline Scott Holdren Michael R. Zachariah

This paper presents a fast CO2 laser synthesis and writing technique - laser photothermal synthesis and writing (LPSW) - to generate and write a high concentration of unaggregated, spherical sub-10 nm metal nanoparticles (sMNPs). The method is generic, and we demonstrate the fabrication of Ni, Cu, and Ag directly in polymer thin films. A partly IR-absorbing thin polymer film can be heated by the laser to high temperatures in a short time, triggering metal-reduction, nucleation, and growth. Rapid quenching of polymer films suppresses particle diffusion and traps the generated sMNPs in the polymer film. As a result, these particles are immobilized in the laser illuminated spot ("written" by the laser) on quenching. Here, Ag-polymer films are used as a model to demonstrate how laser parameters - pulse duration, laser energy flux, and number of pulses (pulsed thermal load) - can be varied to tune particle size distributions of metal sMNPs. Using this approach, we have been able to generate 4-12 nm Ag sMNPs with thermal pulses as short as 35 ms. Fast heating timescales employed in this approach allow for the scalable manufacturing of high yields of metal sMNPs, which we estimate to be around 1 g min-1. This rapid, general synthesis and writing technique may have potentially important applications in fast, large-scale additive manufacturing and patterning of metal-loaded polymer multilayers, flexible electronics, and sensors.

Nanoclusters

Photothermal effect

10.1039/c9nr02839k

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Citations (6)

Preparation and combustion of laminated iodine containing aluminum/polyvinylidene fluoride composites

Combustion and Flame (2018)

Haiyang Wang Scott Holdren Michael R. Zachariah

Polyvinylidene fluoride

Reactivity

Deposition

10.1016/j.combustflame.2018.05.016

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Citations (33)