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Challenges in Water Electrolyzer
Challenges in Water Electrolyzer
Ru-Embedded Carbon Fabric
Ru-Embedded Carbon Fabric
Amine Chemistry of Porous CO2 Adsorbents
Amine Chemistry of Porous CO2 Adsorbents
Boronization of Nickel Foam for Sustainable Electrochemical Reduction of Nitrate to Ammonia
Boronization of Nickel Foam for Sustainable Electrochemical Reduction of Nitrate to Ammonia
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
  • Highly Selective and Scalable Molecular Fluoride Sensor for Naked-Eye Detection

    Zakir Ullah, Saravanan Subramanian, Haeseong Lim, Nesibe A. Dogan, Joo Sung Lee, Thien S. Nguyen*, Cafer T. Yavuz*
    ACS Applied Materials & Interfaces,
    2024
    Highly Selective and Scalable Molecular Fluoride Sensor for Naked-Eye Detection
    Fluoride is widely present in nature, and human exposure to it is generally regarded as inevitable. High levels of fluoride intake induce acute and chronic illnesses. To reduce potential harm to the general public, it is essential to create selective fluoride detectors capable of providing a colorimetric response for naked-eye detection without the need for sophisticated equipment. Here, we report a one-pot synthesis of four different diaminomaleonitrile-derived Schiff base sensors. The terephthalaldehyde adduct provided a strong color change visible to the naked eye at a F– concentration level as low as 2 ppm. From the evaluation against other anions, such as CN–, I–, Br–, Cl–, NO3–, PO43–, OAc–, and HSO4–, the molecular sensor displayed a visible color change exclusively upon exposure to fluoride, underscoring exceptional selectivity. As a key intermediate for understanding the mechanism, HF2– was confirmed by 19F nuclear magnetic resonance. Theoretical calculations suggested a deprotonation-triggered bathochromic shift brought about by the unique electronic structure of the sensor. Furthermore, the simple synthetic protocol from economically accessible materials allowed for the preparation of the compound on a large scale, rendering it a highly practical visual fluoride sensor.
  • Enhancing Ammonia Synthesis on Co3Mo3N via Metal Support Interactions on a Single-crystalline MgO Support

    Rohit K. Rai, Raghu Maligal-Ganesh, Walid Al Maksoud, Seok-Jin Kim, Yuvraj Vaishnav, Cafer T. Yavuz*, Yoji Kobayashi*
    ChemCatChem, 16, e202301579
    2024
    Enhancing Ammonia Synthesis on Co3Mo3N via Metal Support Interactions on a Single-crystalline MgO Support
    Co3Mo3N has been reported to have activity for the synthesis of ammonia surpassing that of industrial Fe catalysts under certain conditions. However, so far the research has largely focused on unsupported Co3Mo3N. We report a comprehensive study on the catalytic activity of Co3Mo3N when supported on two distinct MgO substrates. Our findings reveal that the method of MgO preparation plays a crucial role in influencing surface basicity. Remarkably, Co3Mo3N supported on single-crystalline MgO demonstrates significantly enhanced catalytic activity, achieving a 162.0 mmol g−1metal h−1 rate. This surpasses the performance on commercial MgO support (41.2 mmol g−1metal h−1) and unsupported Co3Mo3N (15.0 mmol g−1metal h−1). While kinetic analyses show no substantial differences between the two supported catalysts, spectroscopic studies employing CO2 and N2 temperature-programmed desorption (TPD) reveal a richer array of basic sites and adsorption/desorption phenomena on the single-crystalline MgO support. These catalysts exhibit exceptional stability. The drastically reduced Co/Mo loading amounts in comparison to the bulk form, make the commercialization of Co3Mo3N catalysts more practical.
  • Ionic Covalent Organic Framework-Based Membranes for Selective and Highly Permeable Molecular Sieving

    Xin Liu, Jinrong Wang, Yuxuan Shang, Cafer T. Yavuz, Niveen M. Khashab*
    Journal of American Chemical Society, 146, 2313–2318
    2024
    Ionic Covalent Organic Framework-Based Membranes for Selective and Highly Permeable Molecular Sieving
    Two-dimensional covalent organic frameworks (COFs) with uniform pores and large surface areas are ideal candidates for constructing advanced molecular sieving membranes. However, a fabrication strategy to synthesize a free-standing COF membrane with a high permselectivity has not been fully explored yet. Herein, we prepared a free-standing TpPa-SO3H COF membrane with vertically aligned one-dimensional nanochannels. The introduction of the sulfonic acid groups on the COF membrane provides abundant negative charge sites in its pore wall, which achieve a high water flux and an excellent sieving performance toward water-soluble drugs and dyes with different charges and sizes. Furthermore, the COF membrane exhibited long-term stability, fouling resistance, and recyclability in rejection performance. We envisage that this work provides new insights into the effect of ionic ligands on the design of a broad range of COF membranes for advanced separation applications.
  • Challenges in Electrolyzer Performance Evaluation for Green Hydrogen Production

    Seok-Jin Kim, Javeed Mahmood, Phil Woong Kang, Zhonghua Xue, and Cafer T. Yavuz*
    ACS Materials Letters 6, 7, 3168–3175
    2024
    Challenges in Electrolyzer Performance Evaluation for Green Hydrogen Production
    The transition to sustainable energy increasingly relies on hydrogen gas produced by water electrolysis. Current performance metrics for electrolyzers, typically measured in megawatts or kilowatts, inadequately capture the full scope of the system efficiency and hydrogen output rates. The gap between academic and industrial evaluations can distort the perceived effectiveness of these technologies. This Perspective proposes a refined dual-metric evaluation system that integrates both energy efficiency (kWh/kg H2) and production rate (Nm3/h) to provide a balanced view of performance. A standardized framework similar to that for photovoltaic technologies is suggested to enable transparent comparisons and support advancements in electrolyzer design. Emphasizing the need for consistent testing conditions, the framework aims to ensure that the evaluations of the electrodes, stacks, and overall systems remain reliable across various operational scenarios. Adopting such a comprehensive evaluation approach is essential for accurately communicating the capabilities of water electrolyzers and propelling the widespread use of green hydrogen.
  • Scalable Design of Ru-Embedded Carbon Fabric Using Conventional Carbon Fiber Processing for Robust Electrocatalysts

    Ga-Hyeun Lee, Jung-Eun Lee, Javeed Mahmood, Gao-Feng Han, Inkyung Baek, Changbeom Jeon, Minjung Han, Hwakyung Jeong, Cafer T. Yavuz*, Han Gi Chae*, and Jong-Beom Baek*
    Journal of the American Chemical Society, 146, 13142–13150
    2024
    Scalable Design of Ru-Embedded Carbon Fabric Using Conventional Carbon Fiber Processing for Robust Electrocatalysts
    Metal–carbon composites are extensively utilized as electrochemical catalysts but face critical challenges in mass production and stability. We report a scalable manufacturing process for ruthenium surface-embedded fabric electrocatalysts (Ru-SFECs) via conventional fiber/fabric manufacturing. Ru-SFECs have excellent catalytic activity and stability toward the hydrogen evolution reaction, exhibiting a low overpotential of 11.9 mV at a current density of 10 mA cm–2 in an alkaline solution (1.0 M aq KOH solution) with only a slight overpotential increment (6.5%) after 10,000 cycles, whereas under identical conditions, that of commercial Pt/C increases 6-fold (from 1.3 to 7.8 mV). Using semi-pilot-scale equipment, a protocol is optimized for fabricating continuous self-supported electrocatalytic electrodes. Tailoring the fiber processing parameters (tension and temperature) can optimize the structural development, thereby achieving good catalytic performance and mechanical integrity. These findings underscore the significance of self-supporting catalysts, offering a general framework for stable, binder-free electrocatalytic electrode design.
  • Highly efficient micropollutant decomposition by ultrathin amorphous cobalt-iron oxide nanosheets in peroxymonosulfate-mediated membrane-confined catalysis

    Muhammad Bilal Asif, Seok-Jin Kim, Thien S Nguyen, Javeed Mahmood, Cafer T Yavuz
    Chemical Engineering Journal, 149352,485
    2024
    Highly efficient micropollutant decomposition by ultrathin amorphous cobalt-iron oxide nanosheets in peroxymonosulfate-mediated membrane-confined catalysis
    Applications of advanced oxidation processes (AOPs) in water treatment require addressing technological challenges such as developing low-cost techniques for nanocatalyst synthesis, overcoming mass transfer limitations, and enhancing the yield of reactive oxygen species (ROS). This study employs a simple sodium borohydride (NaBH4)-based reduction technique for synthesizing ultrathin amorphous cobalt-iron oxide nanosheets (A/Co3-Fe ONS) to activate peroxymonosulfate (PMS). These nanosheets were found to outperform crystalline nanosheets due to their abundant reactive sites, oxygen vacancies, and capability to produce ROS through O–O and S–O bond cleavage. Due to the nanoconfinement effect, converting A/Co3-Fe ONS into a lamellar membrane significantly enhances reactivity and efficacy (1290 times) compared to batch PMS-mediated AOP reactors. Quenching experiments, solid-state and solution-based electron paramagnetic resonance (EPR) spectroscopy facilitated delineation of the reaction mechanisms involving both radical and nonradical pathways. Finally, the A/CoFeOx membrane achieved efficient removal (>95 %) of various organic micropollutants (OMPs), ultrafast destruction (318 ms), and excellent stability (48 h) through redox-recycling facilitated by the redox-potential difference and oxygen vacancies. This strategy offers a low-temperature cost-effective alternative and may be considered for scale-up in water treatment.
  • Disulfide-Linked Covalent Organic Polymers and Method of Preparing the Same

    US 9,346,918. May 24, 2016
    H. A. Patel, C. T. Yavuz
    A disulfide-linked covalent organic polymer and a preparation method thereof are described, and more particularly a disulfide-linked covalent organic polymer prepared by a disulfide formation reaction, a preparation method thereof, and the use of the organic polymer as an organic solvent absorbent. A disulfide-linked covalent organic polymer prepared according to the disclosure may be used as an absorbent capable of selectively absorbing various organic solvents in aqueous solutions or wastewater.
    Granted
  • 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

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