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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
  • Covalent amine tethering on ketone modified porous organic polymers for enhanced CO2 capture

    P. Jorayev, I. Tashov, V. Rozyyev, T. S. Nguyen, N. A. Dogan, C. T. Yavuz
    ChemSusChem, 13, 6433-6441
    2020
    Covalent amine tethering on ketone modified porous organic polymers for enhanced CO2 capture
    Effective removal of excess greenhouse gas CO2 necessitates new adsorbents that can overcome the shortcomings of the current capture methods. To achieve that, porous materials are often modified post-synthetically with reactive amine functionalities but suffer from significant surface area losses. Herein, we report a successful amine post-functionalization of a highly porous covalent organic polymer, COP-130, without losing much porosity. By varying the amine substituents, we recorded a remarkable increase in CO2 uptake and selectivity. Ketone functionality, a rarely accessible functional group for porous polymers, was inserted prior to amination and led to covalent tethering of amines. Interestingly, aminated polymers demonstrated relatively low heats of adsorption, which is useful for the rapid recyclability of materials, due to the formation of suspected intramolecular hydrogen bonding.
  • Precious metal recovery from electronic waste by a porous porphyrin polymer

    Hong, D. Thirion, S. Subramanian, M. Yoo, H. Choi, H. Y. Kim, J. F. Stoddart, C. T. Yavuz
    Proc. Natl. Acad. Sci., 117 (28), 16174-16180
    2020
    Urban mining of precious metals from electronic waste, such as printed circuit boards (PCB), is not yet feasible because of the lengthy isolation process, health risks, and environmental impact. Although porous polymers are particularly effective toward the capture of metal contaminants, those with porphyrin linkers have not yet been considered for precious metal recovery, despite their potential. Here, we report a porous porphyrin polymer that captures precious metals quantitatively from PCB leachate even in the presence of 63 elements from the Periodic Table. The nanoporous polymer is synthesized in two steps from widely available monomers without the need for costly catalysts and can be scaled up without loss of activity. Through a reductive capture mechanism, gold is recovered with 10 times the theoretical limit, reaching a record 1.62 g/g. With 99% uptake taking place in the first 30 min, the metal adsorbed to the porous polymer can be desorbed rapidly and reused for repetitive batches. Density functional theory (DFT) calculations indicate that energetically favorable multinuclear-Au binding enhances adsorption as clusters, leading to rapid capture, while Pt capture remains predominantly at single porphyrin sites.
  • Gold recovery from e-waste by porous porphyrin-phenazine network polymers

    T. S. Nguyen, Y. Hong, N. A. Dogan, C. T. Yavuz
    Chem. Mater., 32, 12, 5343–5349
    2020
    Gold recovery from e-waste by porous porphyrin-phenazine network polymers
    Gold recovery from electronic waste could prevent excessive mining with toxic extractants and provide a sustainable path for recycling precious metals. Unfortunately, no viable recycling is practiced, except burning electronic circuit boards in underdeveloped countries, mainly because of the lack of chemical scavengers as adsorbents. Here, we report the synthesis of a family of porphyrin–phenazine-based polymers and their gold-capturing properties as well as application in gold recovery from actual e-waste. The polymers show high selectivity toward gold as well as other precious metals. The Au(III) adsorption isotherms were well-fitted to the Langmuir adsorption model and proportionality between porosity and uptake capacity was observed. Solution pH values and illumination conditions were shown to have influences on the performance of the adsorbents with the highest capacity of 1.354 g/g obtained in acidic pH and under continuous UV irradiation. Such a remarkable capacity of 7 times the theoretical estimate was achieved through photochemical adsorption–reduction mechanism supported by the observed suppressing effect of oxidant on gold-capturing ability. The adsorbents are robust and recyclable, a significant advantage over other emerging materials.
  • Direct Z-scheme Tannin-TiO2 Heterostructure for Photocatalytic Gold Ion Recovery from Electronic Waste

    K. R. Kim, S. Choi, C. T. Yavuz, Y. S. Nam
    ACS Sustain. Chem. Eng., 8, 19, 7359–7370
    2020
    Direct Z-scheme Tannin-TiO2 Heterostructure for Photocatalytic Gold Ion Recovery from Electronic Waste
    Precious-metal recovery from industrial wastewater has received considerable attention because of rapidly increasing amounts of electronic waste. Existing technologies have yet to be widely applied due to their high cost and low selectivity toward precious-metal ions. Herein, we report a direct Z-scheme tannin–TiO2 heterostructure for selective gold adsorption from electronic waste under solar irradiation. The tannin-coated TiO2 nanoparticles were prepared by a simple dipping method, and under light illumination, both tannin and TiO2 can serve as photosensitive components for the reduction of metal ions, with metal-to-ligand charge transfer from TiO2 to tannin extending the lifetime of the excited electrons. Moreover, no additional electron donors are required because the tannin layer scavenges the reactive oxygen species generated by the holes from the light-activated TiO2 surface. The heterostructure allows for the highly efficient photocatalytic recovery of gold ions, with 11 times higher adsorption capacity in the light compared to the dark. High selectivity toward gold ions was also demonstrated using a metal ion mixture including nine different metal ions that are commonly found in electronic waste. Our findings suggest that the Z-scheme heterostructure of polyphenol and semiconductor provides a promising photochemical pathway for efficient and selective metal ion recovery from electronic waste.
  • The redox and non-redox CO2 utilization: Dry reforming of methane and catalytic cyclic carbonate formation

    S. Subramanian, Y. Song, D. Kim, C. T. Yavuz
    ACS Energy Lett., 5, 5, 1689–1700
    2020
    The redox and non-redox CO2 utilization: Dry reforming of methane and catalytic cyclic carbonate formation
    CO₂ emissions are too large to tackle with a single process, but a combination of avoidance with chemical utilization may be able to slow global warming. In this Focus Review, we identify two large-scale CO₂ conversion processes based on their viability and opposite energy requirements. In the high-energy, stationary path, CO₂ reforming of methane could provide gigatons of CO₂ utilization through synthesis gas. The main problem is the lack of a durable, effective, low-cost dry reforming catalyst. The exothermic cyclic carbonate formation from CO₂ and organic epoxides offers a low-energy, mobile, nonredox route. The catalysts, however, must be metal-free and robust, have a high surface area, and be low-cost while being easily scalable. These two processes could potentially address at least a quarter of all current CO₂ emissions.
  • Triazatruxene Based Ordered Porous Polymer: High Capacity CO2, CH4, H2 Capture, Heterogeneous Suzuki-Miyaura Catalytic Coupling and Thermoelectric Properties

    A. E. Sadak, E. Karakuş, Y. Chumakov, N. A. Dogan, C. T. Yavuz
    ACS Appl. Energy Mater., 3, 5, 4983–4994
    2020
    Triazatruxene Based Ordered Porous Polymer: High Capacity CO2, CH4, H2 Capture, Heterogeneous Suzuki-Miyaura Catalytic Coupling and Thermoelectric Properties
    A hypercrosslinked ultramicroporous and ordered organic polymer network was synthesized from a planar trimer indole building block called triazatruxene (TAT) through anhydrous FeCl3 catalyzed Friedel–Crafts alkylation using methylal as a crosslinker. The polymer network is stable in a variety of chemicals and thermally durable. The hypercrosslinked network TATHCP shows a high BET (Brunauer–Emmet–Teller) specific surface area of 997 m2 g–1 with CO₂ uptake capacity of 12.55 wt % at 273 K, 1.1 bar. Gas selectivities of 38.4 for CO₂/N₂, 7.8 for CO₂/CH₄, 40.6 for CO₂/O₂, and 32.1 for CO₂/CO were achieved through IAST calculation. The PXRD analysis has revealed that TATHCP has a fully eclipsed structure in full agreement with Pawley refinement. The ordered 2D layers provide anisotropy that could be used in catalysis and thermoelectric measurements. After loading with Pd(II), TATHCP-Pd showed high catalytic activity in Suzuki–Miyaura cross coupling reaction with a wide range of reagents and excellent reaction yields of 90–98% with good recyclability. The structure of TATHCP-Pd was found to have two independent molecules of Pd(OAc)2 in the asymmetric unit cell which are arranged between two TATHCP layers. Thermoelectric properties of TATHCP showed a high Seebeck coefficient and ZT, a first and promising example in HCPs with applications in all-organic thermal energy recovery devices.
  • Metal Oxide Supported Catalyst for Dry Reforming and Method of Preparing Syngas Using the Same

    App# 10-2016-0100271 and 10-2017-0099675, 2016.
    C. T. Yavuz, Y. Song, E. Ozdemir
    he present invention relates to: a dry reforming catalyst in which an active material is impregnated on the surface of a metal oxide support, wherein the active material is surrounded by a surfactant; a method for preparing the same; and a method for preparing a synthetic gas by using the catalyst. Since the surfactant on the surface of the active material prevents sintering of the active material and a phenomenon of covering the active surface with carbon, the dry reforming catalyst exhibits high activity for a long time at a high temperature without using a noble metal, thereby being useful in the preparation of a synthesis gas.
    Registered
  • Electroless for efficient recovery of the adsorbed noble metal in the porphyrin polymer-coated porous method

    App # 10-2017-0170184 and 10-2018-0129227 and 10-2018-0162181, 2017.
    C. T. Yavuz, Y. Hong
    he present invention relates to a porous porphyrin polymer and a method for recovering precious metal elements using the same, wherein the porous porphyrin polymer of chemical formula 1, having high selectivity and adsorptivity with respect to precious metal elements, can be applied to the recovery of precious metal elements from a metal leachate of electronic product waste, river water or sea water.
    Registered
  • Novel heterogeneous organic catalyst with pyridyl salicylimine for selective cyclic carbonate formation

    App # 10-2019-0021112, 2019.
    C. T. Yavuz, S. Subramanian
    he present invention relates to a heterogeneous organic catalyst with pyridyl salicylimine and a method for producing a cyclic carbonate using the same. More particularly, it is possible to selectively and continuously synthesize a cyclic carbonate from carbon dioxide and epoxy compounds by using a heterogeneous organic polymer with a novel pyridyl salicylimine functional group as a catalyst, under a relatively mild condition of normal pressure and mild temperature, without additives such as a solvent or a cocatalyst.
    Unexamined

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