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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
  • 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.
  • Covalent Organic Framework Membranes and Water Treatment

    Muhammad Bilal Asif, Seokjin Kim, Thien S Nguyen, Javeed Mahmood, Cafer T Yavuz
    J. Am. Chem. Soc. 2024, 146, 6, 3567–3584
    2024
    Covalent Organic Framework Membranes and Water Treatment
    Covalent organic frameworks (COFs) are an emerging class of highly porous crystalline organic polymers comprised entirely of organic linkers connected by strong covalent bonds. Due to their excellent physicochemical properties (e.g., ordered structure, porosity, and stability), COFs are considered ideal materials for developing state-of-the-art separation membranes. In fact, significant advances have been made in the last six years regarding the fabrication and functionalization of COF membranes. In particular, COFs have been utilized to obtain thin-film, composite, and mixed matrix membranes that could achieve effective rejection (mostly above 80%) of organic dyes and model organic foulants (e.g., humic acid). COF-based membranes, especially those prepared by embedding into polyamide thin-films, obtained adequate rejection of salts in desalination applications. However, the claims of ordered structure and separation mechanisms remain unclear and debatable. In this perspective, we analyze critically the design and exploitation of COFs for membrane fabrication and their performance in water treatment applications. In addition, technological challenges associated with COF properties, fabrication methods, and treatment efficacy are highlighted to redirect future research efforts in realizing highly selective separation membranes for scale-up and industrial applications.
  • 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
    J. Am. Chem. Soc. 2024, 146, 4, 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.
  • Boronization of Nickel Foam for Sustainable Electrochemical Reduction of Nitrate to Ammonia

    Zhong-Hua Xue, Han-Cheng Shen, Peirong Chen, Guang-Xue Pan, Wei-Wei Zhang, Wei-Meng Zhang, Shi-Nan Zhang, Xin-Hao Li, Cafer T Yavuz
    ACS Energy Letters, 8, 3843-3851
    2023
    Boronization of Nickel Foam for Sustainable Electrochemical Reduction of Nitrate to Ammonia
    Electrochemical reduction of aqueous nitrates has emerged as a sustainable and practical approach in combining water treatment and ammonia fertilizer synthesis. However, the development of highly integrated catalytic electrodes with consistently high activity from non-noble metals remains a challenging issue despite the potential to greatly decrease costs and promote real-world applications. Here, we report a high-performance electrode with electron-abundant surfaces obtained from direct boronization of nickel foam, rendering a stable ammonia yield rate of 19.2 mg h–1 cm–2 with high Faradaic efficiency of 94% for NO3–-to-NH3 conversion. The microprocessing lowers the work function and initiates a local electric field for the nickel foam by converting acid-stable surface nickel oxides into dyadic nanosheets composed of metallic nickel and amorphous nickel borates, thus promoting the adsorption and transformation of nitrate anions. Furthermore, the spent electrode enables a rapid and effective regeneration by undergoing another round of boronization, which ensures a long lifetime for the practical application of our electrode design.
  • Catalysts for dry reforming and methods of producing the same

    US20240050933A1
    Cafer Tayyar Yavuz, Seokjin Kim, Aadesh Harale, Bandar Al-Solami, Aqil Jamal
    The disclosure relates to catalysts for dry reforming, methods of producing the catalysts, and methods of using the catalysts in dry reforming. The catalysts contain nickel, molybdenum and a metal oxide. The methods of producing the catalysts include adding a solvent to precipitate the catalyst, followed by removing the solvent. The solvent addition and removal steps can be repeated as desired.
    Pending
  • Solvent-linked porous covalent organic polymers and method of preparing the same

    US Patent 11,535,701,2022
    Cafer T Yavuz, Vepa Rozyyev, Joo Sung Lee
    Solvent-linked porous covalent organic polymers (COPs) and a method of preparing the same are described. The porous covalent organic polymers are linked by a solvent and are thus suitable for the transportation and storage of natural gas. A method of preparing the porous covalent organic polymers by conducting alkylation polymerization between an aromatic monomer and a chlorine-based solvent in the presence of a Lewis acid catalyst is described. Porous stretchable covalent organic polymers having pores with various sizes can be synthesized simply and quickly at room temperature and atmospheric pressure without a heating or purification step. The covalent organic polymers have very high natural gas storage capacity due to the flexible porous network structure thereof and thus are suitable for storage and transportation of natural gas and useful as a natural gas adsorbent.
    Granted
  • Electroless plating solution and electroless plating method for recovering precious metal adsorbed on porous porphyrin polymer

    US Patent App. 17/413,559, 2022
    Jong-In Han, SON JiEun, Cafer Yavuz, HONG Youngran
    The present invention relates to a method for recovering a precious metal selectively adsorbed on a porous porphyrin polymer, and to an electroless plating method capable of recovering a precious metal in a film form by desorbing and leaching the precious metal without an additional oxidizing agent and using same as a plating solution to reduce the precious metal on the surface of a substrate without an additional reducing agent.
    Pending
  • The electrochemical plating apparatus for recovering a noble metal adsorbed to the porous polymeric porphyrin

    App # 10-2018-0162180, 2018.
    C. T. Yavuz, Y. Hong
    The present invention relates to an apparatus and a method of electrochemical plating for recovering precious metals adsorbed on a porous porphyrin polymer, wherein precious metals selectively adsorbed on a porous porphyrin polymer is leached into an electrolyte to be collected in a film shape on a surface of a reducing electrode through electrochemical reduction reaction.COPYRIGHT KIPO 2020
    Registered
  • Natural gas storage utilizing the elastic organic polymer covalent bond which is connected to the solvent

    App # 10-2019-0058296, 2019.
    C. T. Yavuz, V. Rozyyev
    The present invention relates to solvent linked porous covalent organic polymers and a method for preparing the same. More particularly, the present invention relates to porous covalent organic polymers linked by a solvent, thereby being suitable for transport and storage of natural gas, and to a method for preparing the porous covalent organic polymers by adding an aromatic monomer and a chlorine-based solvent in the presence of a Lewis acid catalyst, followed by alkylation. Under the conditions of room temperature and room pressure, it is possible to synthesize porous, elastic and covalent organic polymers having pores of various sizes simply and quickly without a heating step or a purification step. Also, the covalent organic polymers can be used in various ways as an adsorbent for natural gas because the storage capacity of natural gas is very high due to a flexible porous network structure of the covalent organic polymers, thereby being suitable for transport and storage of natural gas.COPYRIGHT KIPO 2021
    Registered
  • Magnetic Purification of a Sample

    US 7,938,969. May 10, 2011.
    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
  • Engineered nanoparticles for water treatment application

    J. Byun, C. T. Yavuz
    2016
    Chapter 2 in Engineered Nanoparticles and the Environment: Biophysicochemical Processes and Toxicity, Edited by B. Xing, C. D. Vecitis, N. Senesi. WILEY-IUPAC Series in Biophysico-Chemical Processes in Environmental Systems Published by John Wiley & Sons, Inc. In this chapter, water treatment processes using nanoparticles and studies related to the removal of waterborne contaminants, such as anionic, cationic, and organic pollutants, will be reviewed.
    Engineered nanoparticles for water treatment application
  • Nano Rust

    Cafer T. Yavuz
    2008
    My first book was recently published via VDM Verlag. Thanks to Gabriel Caruntu for hooking me up with them. If you're interested in buying please click here, it's only $116(!). Here's the blurb from the back: This work describes the first size dependent magneticseparation in nanoscale by using rust like iron oxide. Magnetite (Fe3O4) nanocrystals of high quality and uniform size (4 nm to 33 nm) were synthesized. Batch synthesis was shown to go up to 20 grams which is more than 10 times of a standard nanocrystal synthesis, without loosing the quality and monodispersity. Reactor design for mass (1 gram per hour) production of magnetite nanocrystals isreported for the first time. A green synthesis thatutilizes rust and edible oils was developed. The cost of a kg of magnetite nanocrystals was brought down from $2600 to $22. Size dependency of magnetism was shown in nanoscale for the first time. Reversible aggregation theory was developed to explain the low field magnetic separation and solution behavior of magnetite nanocrystals. Arsenic was removed from drinking water with magnetite nanocrystals 200 times better than commercial adsorbents. Silica coating was successfully applied and magnetite - silica nanoshells were functionalized with amino groups. For the first time, silver was coated on the magnetite -silica nanoshells to produce triple multishells.
    Nano Rust
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