Proceedings
Proceedings
Proceedings

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How Reproducible are Surface Areas Calculated from the BET Equation?
How Reproducible are Surface Areas Calculated from the BET Equation?
Extensive Screening of Solvent-linked Porous Polymers through Friedel-Crafts Reaction for Gas Adsorption
Extensive Screening of Solvent-linked Porous Polymers through Friedel-Crafts Reaction for Gas Adsorption
Alkyl-linked porphyrin porous polymers for gas capture and precious metal adsorption
Alkyl-linked porphyrin porous polymers for gas capture and precious metal adsorption
Quantifying the nitrogen effect on CO2 capture using isoporous network polymers
Quantifying the nitrogen effect on CO2 capture using isoporous network polymers
Direct Access to Primary Amines and Particle Morphology Control in Nanoporous CO2 Sorbents
Direct Access to Primary Amines and Particle Morphology Control in Nanoporous CO2 Sorbents
Enhanced Sorption Cycle Stability and Kinetics of CO2 on Lithium Silicates Using the Lithium Ion Channeling Effect of TiO2 Nanotubes
Enhanced Sorption Cycle Stability and Kinetics of CO2 on Lithium Silicates Using the Lithium Ion Channeling Effect of TiO2 Nanotubes
  • Low-overpotential overall water splitting by a cooperative interface of cobalt-iron hydroxide and iron oxyhydroxide

    Pravin Babar, Komal Patil, Javeed Mahmood, Seok-jin Kim, Jin Hyeok Kim, Cafer T Yavuz
    Cell Reports Physical Science,3, 2, 100762
    2022
    Low-overpotential overall water splitting by a cooperative interface of cobalt-iron hydroxide and iron oxyhydroxide
    Interface engineering is a powerful strategy for modulating electronic structure and enhancing intrinsic activity of electrocatalysts for water splitting. Here, we grow two-dimensional cobalt-iron hydroxide (CoFe-OH) nanosheets on nickel foam substrates and deposit FeOOH nanoparticles in a rapid and scalable wet chemical approach. The CoFe-OH@FeOOH nanocomposite features abundant active sites and high surface area, allowing fast kinetics for electrochemical water splitting. The electrode has a low overpotential value of 200 mV at 50 mA cm−2 for oxygen evolution. When used as both anode and cathode for overall water splitting, CoFe-OH@FeOOH provides a low cell voltage of 1.56 V to deliver 10 mA cm−2 current density. The synergistic activity is presumed to be from the seamless interface of CoFe-OH and FeOOH, improving conductivity and mass transfer. We envision that this simple approach may offer a new direction for designing efficient electrodes for energy conversion applications.
  • Optimizing bromide anchors for easy tethering of amines, nitriles and thiols in porous organic polymers towards enhanced CO2 capture

    V. Rozyyev, M. S. Yavuz, D. Thirion, T. S. Nguyen, T. P. N. Nguyen, A. Emwas, C. T. Yavuz
    Micropor. Mesopor. Mater., 328, 111450
    2021
    Optimizing bromide anchors for easy tethering of amines, nitriles and thiols in porous organic polymers towards enhanced CO2 capture
    Porous organic polymers with labile leaving groups offer direct access to reactive functional groups, otherwise not permissible during network formation. In a one-step, open air, self-coupling reaction of tris bromomethyl benzene, we report highly porous, bromine rich C–C bonded porous polymers. Due to the steric nature of the monomer, restrictive crosslinking allowed pendent bromine groups to remain unreacted and provided rapid exchange into amines, nitriles, and thiols. This simple but powerful strategy yielded two isostructural but varying porosity and pendent group density polymers, allowing a comparative gas uptake study. Despite having lower surface area, the porous polymer formed at low temperature showed higher amination due to higher density of bromine groups. The polymers with more pendant groups resulted better CO2 uptake performances than higher porosity polymers with less pendant groups. Although post-modification decreased surface area of materials, amine functionalization greatly improved the CO₂ uptake capacity. The ethylenediamine appended version exhibited 4.7 times increase in CO₂ uptake capacity with highest CO₂/N₂ selectivity of 729 (298 K), and with an isosteric heat of 97 kJ mol−1 at zero coverage.
  • Design of low cost, scalable, and high-performance TiS2 thermoelectric materials via wet ball-milling process

    P. Veluswamy, S. Subramanian, M. Hassan, C. T. Yavuz, H. J. Ryu, B. J. Cho
    J. Mater. Sci.: Mater. Electron.,
    2021
    Thermoelectric (TE) materials could provide an efficient means for recovering waste heat energy if a low cost, scalable, and high figure-of-merit material could be fabricated. Here, we report, for the first time, a wet ball-milling method to achieve high-performance two-dimensional (2D) semi-metallic TiS2 nanoplatelets. TiO2 is milled, annealed, and sintered with sulfur under high pressure. The addition of a small amount of sulfur (S) powder during the annealing period prevents sulfur deficiency in the sintered compact, resulting in the formation of a near-stoichiometric TiS2 composition. The formation of 2D TiS2 nanoplatelets was confirmed by X-ray diffraction, field emission scanning electron microscopy with energy-dispersive spectroscopy, and X-ray photoelectron spectroscopy. The TE properties were measured in the temperature range of 25–100 °C. Further, we obtain that the prepared TiS2 has as high figure of merit as 0.35 at 100 °C. Novel wet ball mill processing strategies for the development of high-performance 2D materials such as TiS2 make it possible to incorporate these materials for scaled-up device fabrication.
  • Rapid access to ordered mesoporous carbons for chemical hydrogen storage

    U. Jeong§, H. Kim§, S. Ramesh, N. A. Dogan, S. Wongwilawan, S. Kang, J. Park, E. S. Cho, C. T. Yavuz. §: Equal contribution
    Angew. Chem. Int. Ed., 60, 22478–22486
    2021
    Ordered mesoporous carbon materials offer robust network of organized pores for energy storage and catalysis applications, but suffer from time-consuming and intricate preparations hindering their widespread use. Here we report a new and rapid synthetic route for a N-doped ordered mesoporous carbon structure through a preferential heating of iron oxide nanoparticles by microwaves. A nanoporous covalent organic polymer is first formed in situ covering the hard templates of assembled nanoparticles, paving the way for a long-range order in a carbonaceous nanocomposite precursor. Upon removal of the template, a well-defined cubic mesoporous carbon structure was revealed. The ordered mesoporous carbon was used in solid state hydrogen storage as a host scaffold for NaAlH4, where remarkable improvement in hydrogen desorption kinetics was observed. The state-of-the-art lowest activation energy of dehydrogenation as a single step was attributed to their ordered pore structure and N-doping effect.
  • Solvent Vapor Annealing, Defect Analysis, and Optimization of Self-Assembly of Block Copolymers Using Machine Learning Approaches

    G. Ginige, Y. Song, B. C. Olsen, E. J. Luber, C. T. Yavuz, J. M. Buriak
    ACS Appl. Mater. Interfaces, 13, 24, 28639–28649
    2021
    Solvent Vapor Annealing, Defect Analysis, and Optimization of Self-Assembly of Block Copolymers Using Machine Learning Approaches
    Self-assembly of block copolymers (BCPs) is an alternative patterning technique that promises high resolution and density multiplication with lower costs. The defectivity of the resulting nanopatterns remains too high for many applications in microelectronics and is exacerbated by small variations of processing parameters, such as film thickness, and fluctuations of solvent vapor pressure and temperature, among others. In this work, a solvent vapor annealing (SVA) flow-controlled system is combined with design of experiments (DOE) and machine learning (ML) approaches. The SVA flow-controlled system enables precise optimization of the conditions of self-assembly of the high Flory–Huggins interaction parameter (χ) hexagonal dot-array forming BCP, poly(styrene-b-dimethylsiloxane) (PS-b-PDMS). The defects within the resulting patterns at various length scales are then characterized and quantified. The results show that the defectivity of the resulting nanopatterned surfaces is highly dependent upon very small variations of the initial film thicknesses of the BCP, as well as the degree of swelling under the SVA conditions. These parameters also significantly contribute to the quality of the resulting pattern with respect to grain coarsening, as well as the formation of different macroscale phases (single and double layers and wetting layers). The results of qualitative and quantitative defect analyses are then compiled into a single figure of merit (FOM) and are mapped across the experimental parameter space using ML approaches, which enable the identification of the narrow region of optimum conditions for SVA for a given BCP. The result of these analyses is a faster and less resource intensive route toward the production of low-defectivity BCP dot arrays via rational determination of the ideal combination of processing factors. The DOE and machine learning-enabled approach is generalizable to the scale-up of self-assembly-based nanopatterning for applications in electronic microfabrication.
  • Bisphenol–based cyanide sensing: Selectivity, reversibility, facile synthesis, bilateral “OFF-ON” fluorescence, C2ν structural and conformational analysis

    Z. Ullah, P. A. Sonawane, T. S. Nguyen, M. Garai, D. G. Churchill, C. T. Yavuz
    Spectrochim. Acta A, 259, 119881
    2021
    A structurally characterized novel dual–pocketed tetra–conjugated bisphenol–based chromophore (fluorescence = 652 nm) was synthesized in gram scale in ~90% yield from its tetraaldehyde. Highly selective, naked-eye detection of CN− (DMSO/H2O) was confirmed by interferent testing. A detection limit of 0.38 µM, within the permissible limit of CN− concentration in drinking water was achieved as mandated by WHO. The “reversibility” study shows potential applicability and reusability of Sen. Moreover, cost-effective and on-site interfaces, application tools such as fabricated cotton swabs, plastic Petri dishes, and filter papers further demonstrated the specific selectivity of Sen for the toxic CN−. In addition, an easily available and handy smartphone-assisted “Color Picker” app was utilized to help estimate the concentration of CN− ion present. A dual phenol deprotonation mechanism is active and supported by 1H NMR spectroscopic data and DFT calculation results.
  • Dry reforming catalyst using metal oxide support, and method for preparing synthetic gas by using same

    US App 16321028. June 6, 2019. Also filed in 12 other countries
    C. T. Yavuz, E. Ozdemir, Y. Song, A. Harale, B. Fadhel
    The present invention relates to a dry reforming catalyst in which an active material is impregnated on the surface of a metal oxide support and the active material is surrounded by a surfactant, a method of preparing the same, and a method of producing a synthetic gas using the catalyst. Since the surfactant on the surface of the active material prevents the active material from being sintered and the active material surface from being covered with carbon, the dry reforming catalyst exhibits high activity at high temperature for a long period of time without having to use a precious metal, and thus is useful for the production of a synthetic gas.
    Pending
  • Porous porphyrin polymer and method of recovering precious metal elements using the same

    US App 16212052, June 27, 2019. Also filed in Japan.
    C. T. Yavuz, Y. Hong, D. Thirion, S. Subramanian
    A porous porphyrin polymer and a method of recovering precious metal elements using the same are described. A porous porphyrin polymer represented by Formula 1 has high selectivity for precious metal elements and a high ability to adsorb precious metal elements, and can be applied to the recovery of precious metal elements either from metal leachates of waste electronic products or from river water or seawater.
    Granted
  • Metal Oxide Nanocrystal Composition and Methods

    WO/2008/136855,November 13, 2008.
    C. T. Yavuz, V. L. Colvin
    Improved methods of making magnetic nanocrystals are provided. According to certain embodiments, a method of making magnetic nanocrystals is provided, the method comprising: providing a metal component comprising at least one metal component selected from the group consisting of: a metal oxide; a metal hydroxide; a metal hydrate; and any combination thereof; providing an oil comprising a free acid; and reacting the metal component and the oil comprising a free acid at a temperature sufficient to form metal oxide nanocrystals.
    Granted
  • Methods for Separating Magnetic Nanoparticles

    WO/2008/136853,November 13, 2008.
    C. T. Yavuz, V. L. Colvin, W. W. Yu, J. T. Mayo
    Methods for separating magnetic nanoparticles are provided. In certain embodiments, a method is provided for separating magnetic nanoparticles comprising: providing a sample comprising a plurality of magnetic nanoparticles; passing the sample through a first magnetic field; at least partially isolating nanoparticles of the first nanoparticle size desired; altering the strength of the first magnetic field to produce a second magnetic field; and at least partially isolating nanoparticles of the second nanoparticle size desired.
    Granted
  • Method for manufacturing alkaline earth metal hexaferrite nano-particles, g alkaline earth metal hexaferrite nano-particles manufactured by the same, and shield material for ultra high frequence wave comprising the same

    KR 10-1355964,Jan 21, 2014.
    C. T. Yavuz, H. A. Patel, J. Byun
    Provided are a method for preparing alkaline earth hexaferrite nanoparticles, and alkaline earth metal hexaferrite nanoparticles prepared thereby, and a microwave shielding material including the same. Alkaline earth metal hexaferrite nanoparticle manufacturing method according to an embodiment of the present invention comprises the steps of mixing the first mixture and the carboxylic acid group-containing compound in a solvent to form a second mixture; And a first heat treatment of the second mixture to prepare alkaline earth metal hexaferrite nanoparticles. According to the present invention, a single crystal of barium hexaferrite (BHF) and strontium hexaferrite (SHF) and The same alkaline earth hexaferrite nanoparticles can be obtained by pyrolysis of metal-carboxylates. The alkaline earth metal hexaferrite nanoparticles thus obtained show a single domain structure and can be effectively used for microwave shielding.
    Registered
  • Barium Hexaferrite Nanofiber Filter and Method for Removing Heavy Metals and Separating Magnetic Nano Particles Using the Same

    KR 10-1433332,Aug 18, 2014.
    C. T. Yavuz, H. A. Patel, J. Byun
    The present invention relates to a barium hexaferrite nanofiber filter and a method for removing heavy metals using the same and, more specifically, to a method for separating, from aqueous media, magnetite having arsenic adsorbed thereto using barium hexaferrite nanofiber which shows the highest level of saturable magnetism of nanofibers. The barium hexaferrite nanofiber according to the present invention can separate magnetite particles completely from aqueous media owing to high magnetism, and can have high possibility of commercialization as the barium hexaferrite nanofiber can be woven in the shape of a filter and a continuous process method can be introduced. In addition, the barium hexaferrite nanofiber can be used practically in a water treatment site and thus can be supplied at low costs to some developing countries that have serious arsenic intoxication problems, as the barium hexaferrite nanofiber is easy to synthesize, and material costs and production costs are very low.
    Granted

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