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Publications

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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
  • Nanoporous networks as effective stabilisation matrixes for nanoscale zero valent iron and groundwater pollutant removal

    D. Mines, J. Byun, Y. Hwang, H. A. Patel, H. R. Andersen, C. T. Yavuz
    Mater. Chem. A, 4, 632-639
    2016
    Nanoporous networks as effective stabilisation matrixes for nanoscale zero valent iron and groundwater pollutant removal
    Nanoscale zero-valent iron (nZVI), with its reductive potentials and wide availability, offers degradative remediation of environmental contaminants. Rapid aggregation and deactivation hinder its application in real-life conditions. Here, we show that by caging nZVI into the micropores of porous networks, in particular Covalent Organic Polymers (COPs), we dramatically improved its stability and adsorption capacity, while still maintaining its reactivity. We probed the nZVI activity by monitoring azo bond reduction and Fenton type degradation of the naphthol blue black azo dye. We found that depending on the wettability of the host COP, the adsorption kinetics and dye degradation capacities changed. The hierarchical porous network of the COP structures enhanced the transport by temporarily holding azo dyes giving enough time and contact for the nZVI to act to break them. nZVI was also found to be more protected from the oxidative conditions since access is gated by the pore openings of COPs.
  • Insights of CO2 Adsorption Performance of Amine Impregnated Mesoporous Silica (SBA-15) at Wide Range Pressure and Temperature Conditions

    R. Ullah, M. Atilhan, A. Canlier, S. Aparicio, C. T. Yavuz
    Int. J. Greenh. Gas Control
    2015
    Insights of CO2 Adsorption Performance of Amine Impregnated Mesoporous Silica (SBA-15) at Wide Range Pressure and Temperature Conditions
    Beside IGCC, efficient storage and transportation of CO2 and other gases require pressurize conditions. CO2 and other gases adsorption on solid sorbents at high pressure and various temperatures are extremely important as long as the environmental purification via gas capture and separation and gas transpiration are concern. The main objective of the present research was to investigate the effect of amine impregnation on the CO2, methane and nitrogen adsorption capacity of mesoporous silica (SBA-15). Ordered mesoporous silica (SBA-15) was prepared and modified with ammonium hydroxide solution to introduce NH2 functional groups within the pores of materials to produce modified SBA-15 (MSBA-15). The newly prepared materials were characterized with X-ray diffraction analysis, thermogravimetric analysis (TGA), Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM) and Brunauer-Emmett-Teller (BET) analysis were performed to measure pore volume as well as the surface area of both the unmodified and modified samples. Results revealed that the crystal structures of SBA-15 were matched with that of MSBA15; yet, pore volume of the modified material was almost reduced to 50% of the pristine material indicating amine loading into the pore channels. Importantly, gas sorption capacity was investigated at 200bars and three different temperatures of 318K, 328K, and 338K by using state-of-the-art gravimetric Rubotherm® magnetic suspension sorption apparatus. Gas sorption experiments showed that modified mesoporous silica adsorbed 1.6164mmol/g of CO2 at 1bar which is almost double than that of 0.6462mmol/g adsorbed by unmodified material. Quantitative selectivity of both the materials varied as CO2>CH4>N2
  • Covalent organic polymer framework with C-C bonds as a fluorescent probe for selective iron detection

    E. Ozdemir, D. Thirion, C. T. Yavuz
    RSC Adv., 5, 69010-69015
    2015
    Covalent organic polymer framework with C-C bonds as a fluorescent probe for selective iron detection
    A new carbon–carbon bonded nanoporous polymer network was synthesized via efficient and catalyst free Knoevenagel-like condensation polymerization in near quantitative yields. The obtained polymer network, Covalent Organic Polymer – COP-100 possesses strong fluorescent properties and designed solubility in polar aprotic solvents, which shows promise for use as a metal-sensing material in solution. COP-100 exhibited high selectivity towards Fe2+ and Fe3+ in the presence of other common metal cations (Al3+, Ag+, Cd2+, Co2+, Cr3+, Cu2+, Hg2+, Mg2+, Mn2+, Na+, Ni2+, Zn2+) as the fluorescence of the polymer was significantly quenched even at very low concentrations. In the range from 2.5 × 10−6 to 2 × 10−4 M, a linear fluorescence emission response with equipment limited detection minimum of 2.13 × 10−7 M and 2.45 × 10−7 M for Fe2+ and Fe3+, respectively, was observed. These results suggest that COP-100 is a promising material as a selective fluorescence sensor for iron ions.
  • Systematic investigation of the effect of polymerization routes on the gas sorption properties of nanoporous azobenzene polymers

    O. Buyukcakir, S. H. Je, J. Park, H. A. Patel, Y. Jung, C. T. Yavuz, A. Coskun
    Chem. Eur. J., 21 (43), 15320–15327
    2015
    Systematic investigation of the effect of polymerization routes on the gas sorption properties of nanoporous azobenzene polymers
    Same but different: Chemically similar nanoporous azobenzene polymers that are synthesized by using different polymerization routes show completely different gas-sorption characteristics (see figure). Pore widths of 6–8 Å and small particle sizes are very critical for high CO2/N2 selectivity. Furthermore, N2 phobicity is associated with the azo linkages and is realized at warm temperatures.
  • Highly optimized CO2 capture by inexpensive nanoporous covalent organic polymers and their amine composites

    H. A. Patel, C. T. Yavuz
    Faraday Discuss., 183, 401-412
    2015
    Highly optimized CO2 capture by inexpensive nanoporous covalent organic polymers and their amine composites
    Carbon dioxide (CO2) storage and utilization requires effective capture strategies that limit energy penalties. Polyethylenimine (PEI)-impregnated covalent organic polymers (COPs) with a high CO2 adsorption capacity are successfully prepared in this study. A low cost COP with a high specific surface area is suitable for PEI loading to achieve high CO2 adsorption, and the optimal PEI loading is 36 wt%. Though the adsorbed amount of CO2 on amine impregnated COPs slightly decreased with increasing adsorption temperature, CO2/N2 selectivity is significantly improved at higher temperatures. The adsorption of CO2 on the sorbent is very fast, and a sorption equilibrium (10% wt) was achieved within 5 min at 313 K under the flow of simulated flue gas streams. The CO2 capture efficiency of this sorbent is not affected under repetitive adsorption–desorption cycles. The highest CO2 capture capacity of 75 mg g−1 at 0.15 bar is achieved under dry CO2 capture however it is enhanced to 100 mg g−1 in the mixed gas flow containing humid 15% CO2. Sorbents were found to be thermally stable up to at least 200 °C. TGA and FTIR studies confirmed the loading of PEIs on COPs. This sorbent with high and fast CO2 sorption exhibits a very promising application in direct CO2 capture from flue gas.
  • Nanoporous networks as caging supports for uniform, surfactant-free Co3O4 nanocrystals and their applications in energy storage and conversion

    J. Byun, H. A. Patel, D. J. Kim, C. H. Jung, J. Y. Park, J. W. Choi, C. T. Yavuz
    J. Mater. Chem. A, 3, 15489 - 15497
    2015
    Nanoporous networks as caging supports for uniform, surfactant-free Co3O4 nanocrystals and their applications in energy storage and conversion
    We report a new, surfactant-free method to produce Co3O4 nanocrystals with controlled sizes and high dispersity by caging templation of nanoporous networks. The morphologies of Co3O4 nanoparticles differ from wires to particulates by simply varying solvents. The composites of nanoparticles within network polymers are highly porous and are promising for many applications where accessible surface and aggregation prevention are important. The electrochemical performance of the composites demonstrates superior capacity and cyclic stability at a high current density (∼980 mA h g−1 at the 60th cycle at a current density of 1000 mA g−1). In a catalytic oxidation reaction of carbon monoxide, the composites exhibit a remarkable stability (in excess of 35 hours) and catalytic performance (T100 = 100 °C).

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