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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
  • An electrocatalytic iodine oxidations-based configuration for hydrogen and I2/I3− co-productions driven by the Zn-air/iodine battery

    Chang Chen, Libo Zhu, Javeed Mahmood, Zhong-Hua Xue, Xu Yu, Qin Li, Ziwei Chang, Han Tian, Fantao Kong, Haitao Huang, Cafer T. Yavuz, Xiangzhi Cui, Jianlin Shi
    Energy Storage Materials
    2024
    An electrocatalytic iodine oxidations-based configuration for hydrogen and I2/I3− co-productions driven by the Zn-air/iodine battery
    Electrochemical water splitting and energy storage are key for a sustainable energy future, despite the challenges related to undesirable overpotentials and high voltage requirements. Herein, we introduce a synergistic approach between a low overpotential hydrogen evolution reaction (HER) and a low voltage zinc-air/iodine battery (ZAIB) by coupling with iodide oxidation half reactions. By developing a Pt/Co3O4 electrocatalyst in two steps and with under 2% Pt loading, we achieve an unprecedented low full cell potential for hydrogen generation at 0.574 V, exhibiting an ultra-high reduction of energy consumption of 64.7%. The Pt/Co3O4 electrode also enables ZAIB to record a power density of 154 mW cm−2 at an ultra-low charging potential of 1.68 V. Mechanistic studies and DFT calculations of the novel electrode confirm an electron rich Pt-Co interface and favorable Pt-I interactions, facilitating both HER and IOR reactions. Our design provides critical technology for potential large-scale renewable energy projects.
  • Ultrahigh Single Au Atoms Loaded Porous Aromatic Frameworks for Enhanced Photocatalytic Hydrogen Evolution

    Yuting Yang, Yang Xiao, Li Jiang, Jiahui Li, Jialu Li, Jiangtao Jia, Cafer T. Yavuz, Fengchao Cui, Xiaofei Jing*, Guangshan Zhu*
    Advanced Materials,
    2024
    Ultrahigh Single Au Atoms Loaded Porous Aromatic Frameworks for Enhanced Photocatalytic Hydrogen Evolution
    Supported single-atom catalysts (SACs) are promising in heterogeneous catalysis because of their atom economy, unusual transformations, and mechanistic clarity. The metal SAs loading, however, limits the catalytic efficiency. Herein, an in situ pre-metallated monomer-based preparation strategy is shown to achieve ultrahigh Au SAs loading in catalyst formations. The polymerization of single-atom loaded monomers yield a new porous aromatic framework (PAF-164) with Au SAs loading up to a record high 45.3 wt.%. SACs of Au-PAFs exhibit excellent photocatalytic activity in hydrogen (H2) evolution, and the H2 evolution rate of Au100%-SAs-PAF-164 can reach 4.82 mmol g−1 h−1 with great recyclability.
  • Catalytic enantioselective intramolecular hydroamination of alkenes using chiral aprotic cyclic urea ligand on manganese (II)

    Bin Cui, Yuting Zheng, Hui Sun*, Huijian Shang, Man Du, Yuxuan Shang, Cafer T. Yavuz*
    Nature Communications, 15, 6647
    2024
    Catalytic enantioselective intramolecular hydroamination of alkenes using chiral aprotic cyclic urea ligand on manganese (II)
    Asymmetric catalysis for enantioselective intramolecular hydroamination of alkenes is a critical method in the construction of enantioenriched nitrogen-containing rings, often prevalent in biologically active compounds and natural products. Herein, we demonstrate a facile enantioselective intramolecular hydroamination of alkenes for the synthesis of chiral pyrrolidine, piperidine, and indoline moieties, using a manganese (II) chiral aprotic cyclic urea catalyst. The cyclic ligand hinders the inversion of the N atom of the urea and effectively discriminate between the enantiomers of substrates. High-resolution mass spectrometry, deuterium labeling experiments, and molecular orbital energy analysis clearly reveal the intermediates and mechanism of the transformation. As a key step, oxygen coordination by chiral aprotic urea presents a robust control over the asymmetric intra-HA reaction through the involvement of a convergent assembly of two vital intermediates (Mn-N and C-Mn-Br), providing access to chiral cyclic amine systems in high yields with excellent enantioselectivity.
  • Sunlight-boosted recovery of precious metal ions from E-waste using tannin-grafted mesoporous silica

    Jeonga Kim, Kimoon Lee, Cafer T. Yavuz, Yoon Sung Nam*
    Chemical Engineering Journal, 2024, 487, 150529
    2024
    Sunlight-boosted recovery of precious metal ions from E-waste using tannin-grafted mesoporous silica
    The escalating demand and dwindling reserves of precious metals request efficient recycling techniques from electron waste. Addressing this need, we introduce a new method utilizing tannin-grafted mesoporous silica for the sunlight-boosted recovery of precious metals. Our strategy leverages the inherent photoreactivity of tannins, enabling metal–ligand complexation and plasmonic enhancement of chemical reduction. The result is a marked increase in the adsorption capacity and the high selectivity towards precious metal ions in electronic waste. Our robust covalent bonding approach concentrated tannic acids onto silica at a high density (500,000 per square micrometer), which significantly boosted the adsorption of gold ions up to an 11-fold increase, even amidst a mixture of nine other metal species. Impressively, we achieved a maximum adsorption capacity of 68.4 mmol per gram, equivalent to 13.4 g of gold per gram of adsorbent. Also, the adsorption rates for platinum and palladium ions were enhanced by 2.6 and 3.0 times, respectively. The underlying mechanism includes the visible-light-driven plasmonic hot electron transfer that affords nearly perfect selectivity for gold ions (approximately 99%). These findings not only advance the field of metal recovery from electronic waste but also offer an environmentally benign and cost-effective solution that harnesses renewable solar energy.
  • Evolution of Oxygen Vacancy Sites in Ceria-Based High-Entropy Oxides and Their Role in N2 Activation

    Omer Elmutasim, Aseel G. Hussien, Abhishek Sharan, Sara AlKhoori, Michalis A. Vasiliades, Inas Magdy Abdelrahman Taha, Seokjin Kim, Messaoud Harfouche, Abdul-Hamid Emwas, Dalaver H. Anjum, Angelos M. Efstathiou, Cafer T. Yavuz, Nirpendra Singh* Kyriaki Po
    ACS Applied Materials & Interfaces, 16, 23038-23053
    2024
    Evolution of Oxygen Vacancy Sites in Ceria-Based High-Entropy Oxides and Their Role in N2 Activation
    In this work, a relatively new class of materials, rare earth (RE) based high entropy oxides (HEO) are discussed in terms of the evolution of the oxygen vacant sites (Ov) content in their structure as the composition changes from binary to HEO using both experimental and computational tools; the composition of HEO under focus is the CeLaPrSmGdO due to the importance of ceria-related (fluorite) materials to catalysis. To unveil key features of quinary HEO structure, ceria-based binary CePrO and CeLaO compositions as well as SiO2, the latter as representative nonreducible oxide, were used and compared as supports for Ru (6 wt % loading). The role of the Ov in the HEO is highlighted for the ammonia production with particular emphasis on the N2 dissociation step (N2(ads) → Nads) over a HEO; the latter step is considered the rate controlling one in the ammonia production. Density functional theory (DFT) calculations and 18O2 transient isotopic experiments were used to probe the energy of formation, the population, and the easiness of formation for the Ov at 650 and 800 °C, whereas Synchrotron EXAFS, Raman, EPR, and XPS probed the Ce–O chemical environment at different length scales. In particular, it was found that the particular HEO composition eases the Ov formation in bulk, in medium (Raman), and in short (localized) order (EPR); more Ov population was found on the surface of the HEO compared to the binary reference oxide (CePrO). Additionally, HEO gives rise to smaller and less sharp faceted Ru particles, yet in stronger interaction with the HEO support and abundance of Ru–O–Ce entities (Raman and XPS). Ammonia production reaction at 400 °C and in the 10–50 bar range was performed over Ru/HEO, Ru/CePrO, Ru/CeLaO, and Ru/SiO2 catalysts; the Ru/HEO had superior performance at 10 bar compared to the rest of catalysts. The best performing Ru/HEO catalyst was activated under different temperatures (650 vs 800 °C) so to adjust the Ov population with the lower temperature maintaining better performance for the catalyst. DFT calculations showed that the HEO active site for N adsorption involves the Ov site adjacent to the adsorption event.
  • Sustainable Gas Storage: CO2 Activation of Edge-Functionalized Graphitic Nanoplatelets

    Seok-Jin Kim, Min Hui Kim, Se Jung Lee, Cafer T. Yavuz*, In-Yup Jeon*
    ChemSusChem, 17, e202301145
    2024
    Sustainable Gas Storage: CO2 Activation of Edge-Functionalized Graphitic Nanoplatelets
    Graphitic nanoplatelets (GnPs), edge-selectively carboxylated graphitic nanoplatelets (ECGnPs), are functionalized with a carboxylic acid at the edge increasing their surface area, and are highly dispersible in various solvents. However, there is a limit in that the basal plane remains intact because it is functionalized only in the part where the radical is generated at the edge. Here, we activate ECGnPs to have porous structures by flowing CO2 at 900 °C. Etching of the ECGnPs structure was performed through the Boudouard reaction, and the surface area increased from 579 m2 g−1 to a maximum of 2462 m2 g−1. In addition, the pore structure was investigated with various adsorption gases (CH4, Ar, CO2, H2, and N2) according to the reaction time. This study provides the overall green chemistry in that it utilizes CO2 from manufacturing to activation compared to the process of activating with conventional chemical treatment.
  • 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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