Glass was used as substrates for the synthesis of ZnS/PbS heterostructure using simply one-step t... more Glass was used as substrates for the synthesis of ZnS/PbS heterostructure using simply one-step thermal evaporation method. The surface morphology and structural studies were carefully researched using various characterization methods such as scanning electron microscopy (SEM), high-resolution transmission electron microscopy (HRTEM), X-ray diffraction (XRD) techniques, X-ray Photoelectron Spectroscopy (XPS), and micro-photoluminescence (PL). Our results indicate that the obtained nanostructures are composed mainly of nanorods with length of few microns and thickness of up 100 nm. The ZnS/PbS nanocrystalline consists of cubic phase and polycrystalline in nature. The photoluminescence performance of the system was investigated. At least one luminescence center gives a red emission under 488 nm excitation is identified. Another luminescence center at 1350 nm could be assigned to the PbS quantum dots, which can be utilized to produce infrared solar cells. Produce efficient infrared solar cells.
ABSTRACT The purpose of this research was to use polyamino carboxylic acids (PACAs) and their com... more ABSTRACT The purpose of this research was to use polyamino carboxylic acids (PACAs) and their combination with sodium hypophosphite (NaH2PO2) as a flame-retardant finishing system for cotton fabrics. Flammability of cotton fabric was evaluated by 45� flammability test, differential scanning calorimetry and measuring the char yield. The combination of polyamino carboxylic acids and sodium hypophosphite as a phosphorus-containing catalyst reduces the flammability of cotton. The pyrolysis properties and the results of char yield of the finished cotton show that with increasing amount of catalyst, the flame retardancy increases. Fastness against multiple laundering, whiteness and tensile strength of the cotton finished with PACAs/NaH2PO2 to multiple standard laundering have been studied, too. The flame retardancy effect has an acceptable washing fastness. Whiteness and tensile strength of the finished cotton do not change significantly.
Zinc sulfide (ZnS) and zinc sulfide/lead sulfide (ZnS/PbS) nanorods were grown on glass substrate... more Zinc sulfide (ZnS) and zinc sulfide/lead sulfide (ZnS/PbS) nanorods were grown on glass substrates using a thermal evaporation method. The morphology of the prepared samples has been studied by transmission electron microscopy (TEM), field-emission scanning electron microscopy (FE-SEM) and Scanning Electron Microscopy (SEM). Both differences and similarities in morphology between the samples have been discovered. In the ZnS/PbS sample, ZnS nanorods were formed with diameter less than 50 nm and length between 2000 and 3000 nm. The pure ZnS sample has dense structure and its thickness was about 200 nm. Samples were studied in detail using energy-dispersive X-ray spectroscopy (EDX). The surface chemical compositions of the samples were confirmed by means of X-ray photoelectron spectroscopy (XPS). The determination of the crystal structure using the X-ray diffraction revealed that two phases of ZnS, blende and wurtzite, are present in the sample after adding Pb, while only blende is identified in the pure ZnS sample.
In this work, the possibility of using nano-porous materials for the separation and storage of no... more In this work, the possibility of using nano-porous materials for the separation and storage of noble gases from the off-gas steam generated during the operation of nuclear reprocessing units was theoretically explored. To this end, simulations using the Grand Canonical Monte Carlo (GCMC) method were performed on a wide range of pressure to predict isothermal adsorption at the unit working temperature (323 K) and room temperature (298 K) for a gas mixture of Xe, Kr, N 2 and Ar in eight different materials, which all vary in metal ions, pore size and available surface area. This allows us to have a detailed insight at the molecular level of adsorption mechanisms. Results can be used to help designing multi-stage membrane, where only one noble gas will be captured and stored in each stage.
In this work, the storage of pure CO 2 and CH 4 gases and separation of their binary mixture in n... more In this work, the storage of pure CO 2 and CH 4 gases and separation of their binary mixture in new type of nanostructured materials called boron imidazolate frameworks (BIFs) have been investigated using atomistic simulation to provide information for material selection in adsorbent designs. Adsorption isotherms and adsorption selectivities were computed using grand canonical Monte Carlo (GCMC). Our results showed that BIFs exhibit significantly higher selectivities for separation of CO 2 from CH 4 compared to other widely studied metal organic framework (MOF) materials.
An entry from the Cambridge Structural Database, the world's repository for small molecule cr... more An entry from the Cambridge Structural Database, the world's repository for small molecule crystal structures. The entry contains experimental data from a crystal diffraction study. The deposited dataset for this entry is freely available from the CCDC and typically includes 3D coordinates, cell parameters, space group, experimental conditions and quality measures.
An entry from the Cambridge Structural Database, the world's repository for small molecule cr... more An entry from the Cambridge Structural Database, the world's repository for small molecule crystal structures. The entry contains experimental data from a crystal diffraction study. The deposited dataset for this entry is freely available from the CCDC and typically includes 3D coordinates, cell parameters, space group, experimental conditions and quality measures.
The catalytic activity and stability of metal nanocatalysts toward agglomeration and detachment d... more The catalytic activity and stability of metal nanocatalysts toward agglomeration and detachment during their preparation on a support surface are major challenges in practical applications. Herein, we report a novel, one-step, synchronized electro-oxidation-reduction "bottom-up" approach for the preparation of small and highly stable Cu nanoparticles (NPs) supported on a porous inorganic (TiO2@SiO2) coating with significant catalytic activity and stability. This unique embedded structure restrains the sintering of CuNPs on a porous TiO2@SiO2 surface at a high temperature and exhibits a high reduction ratio (100% in 60 s) and no decay in activity even after 30 cycles (>98% conversion in 3 min). This occurs in a model reaction of 4-nitrophenol (4-NP) hydrogenation, far exceeding the performance of most common catalysts observed to date. More importantly, nitroarene, ketone/aldehydes, and organic dyes were reduced to the corresponding compounds with 100% conversion. Density functional theory (DFT) calculations of experimental model systems with six Cu, two Fe, and four Ag clusters anchored on the TiO2 surface were conducted to verify the experimental observations. The experimental results and DFT calculations revealed that CuNPs not only favor the adsorption on the TiO2 surface over those of Fe and AgNPs but also boost the adsorption energy and activity of 4-NP. This strategy has also been extended to the preparation of other single-atom catalysts (e.g., FeNPs-TiO2@SiO2 and AgNPs-TiO2@SiO2), which exhibit excellent catalytic performance.
An entry from the Cambridge Structural Database, the world's repository for small molecule cr... more An entry from the Cambridge Structural Database, the world's repository for small molecule crystal structures. The entry contains experimental data from a crystal diffraction study. The deposited dataset for this entry is freely available from the CCDC and typically includes 3D coordinates, cell parameters, space group, experimental conditions and quality measures.
Practical methods for hydrogen storage are still a prime challenge in the realization of an energ... more Practical methods for hydrogen storage are still a prime challenge in the realization of an energy economy based on Hydrogen. Metal organic frameworks (MOFs) are crystalline ultra-porous materials with ability to trap and store voluminous amounts of gas molecules. MOFs represent an encouraging storage method relying on their enormous surface area. However, MOFs show reduced hydrogen uptake at room temperature due to low adsorption energy of hydrogen. To increase the adsorption uptake of MOFs at room temperature, the adsorption energy must be increased. In this contribution, materials exhibiting higher adsorption energy and enhanced hydrogen adsorption, namely MIL-53 (Al) and MOF-74, have been investigated using molecular dynamics (MD) simulation. MD simulations were performed within the density functional based tight binding method (DC-SCC-DFTB). Our results demonstrate that DC-SCC-DFTB method predicts structural parameters, adsorption sites, adsorption energies and diffusion factor...
Summary In this study structural characteristics of several carbon based nanostructures and organ... more Summary In this study structural characteristics of several carbon based nanostructures and organic frameworks as metal organic frameworks (MOF) and covalent organic frameworks (COF) on the hydrogen abundance in the material are investigated with the quantized liquid density functional theory (QLDFT), Molecular Dynamics (MD) and Grand Canonical Monte Carlo (GCMC). We applied these theories to evaluate the hydrogen storage capacities of nanoporous materials: Compact storage of hydrogen is the key challenge facing adoption of hydrogen as fuel for mobile applications. A promising approach to increase the storage densities is the adsorption of molecular hydrogen in porous environments. We have studied in detail the role of the host structure, the pressure and temperature dependence as well as the importance of quantum effects on the hydrogen storage capacity of a broad range of materials. A critical comparison with available experimental data is also given
The chemical and physical features of metal organic frameworks (MOFs) at a molecular level are of... more The chemical and physical features of metal organic frameworks (MOFs) at a molecular level are of great merit to understand structure–property relationships and, consequently, to aid in the design of improved high value products. This paper reports on the processing of one MOF-type material, namely MIL-101(Cr), by γ-ray irradiation at low doses up to 30 kGy. The optimum dose is determined to be 15 kGy, at which an increase in the adsorption of iodine of more than 40% is achieved in comparison with thermally activated un-irradiated MIL-101(Cr). Scanning electron microscopy, X-ray diffraction and the Brunauer−Emmett−Teller (BET) isotherms indicate a significant particle agglomeration and a preservation of both the unit cell topology as well as the mesoporous structure of MOF. Two-dimensional correlation Fourier transformation infrared and X-ray diffraction reveals that orientation is the driving force for structural alterations including water type, bonding and contents. These effects...
International Journal of Hydrogen Energy, May 1, 2011
A multiscale approach is used to investigate the hydrogen adsorption in nanoporous Zeolite Imidaz... more A multiscale approach is used to investigate the hydrogen adsorption in nanoporous Zeolite Imidazolate Frameworks (ZIFs) on varying geometries and organic linkers. Ab initio calculations are performed at the MP2 level to obtain correct interaction energies between hydrogen molecules and the ZIF structures. Subsequently, classical grand canonical Monte-Carlo (GCMC) simulations are carried out to obtain the hydrogen uptake of ZIFs at different thermodynamic conditions of pressure and temperature.
Glass was used as substrates for the synthesis of ZnS/PbS heterostructure using simply one-step t... more Glass was used as substrates for the synthesis of ZnS/PbS heterostructure using simply one-step thermal evaporation method. The surface morphology and structural studies were carefully researched using various characterization methods such as scanning electron microscopy (SEM), high-resolution transmission electron microscopy (HRTEM), X-ray diffraction (XRD) techniques, X-ray Photoelectron Spectroscopy (XPS), and micro-photoluminescence (PL). Our results indicate that the obtained nanostructures are composed mainly of nanorods with length of few microns and thickness of up 100 nm. The ZnS/PbS nanocrystalline consists of cubic phase and polycrystalline in nature. The photoluminescence performance of the system was investigated. At least one luminescence center gives a red emission under 488 nm excitation is identified. Another luminescence center at 1350 nm could be assigned to the PbS quantum dots, which can be utilized to produce infrared solar cells. Produce efficient infrared solar cells.
ABSTRACT The purpose of this research was to use polyamino carboxylic acids (PACAs) and their com... more ABSTRACT The purpose of this research was to use polyamino carboxylic acids (PACAs) and their combination with sodium hypophosphite (NaH2PO2) as a flame-retardant finishing system for cotton fabrics. Flammability of cotton fabric was evaluated by 45� flammability test, differential scanning calorimetry and measuring the char yield. The combination of polyamino carboxylic acids and sodium hypophosphite as a phosphorus-containing catalyst reduces the flammability of cotton. The pyrolysis properties and the results of char yield of the finished cotton show that with increasing amount of catalyst, the flame retardancy increases. Fastness against multiple laundering, whiteness and tensile strength of the cotton finished with PACAs/NaH2PO2 to multiple standard laundering have been studied, too. The flame retardancy effect has an acceptable washing fastness. Whiteness and tensile strength of the finished cotton do not change significantly.
Zinc sulfide (ZnS) and zinc sulfide/lead sulfide (ZnS/PbS) nanorods were grown on glass substrate... more Zinc sulfide (ZnS) and zinc sulfide/lead sulfide (ZnS/PbS) nanorods were grown on glass substrates using a thermal evaporation method. The morphology of the prepared samples has been studied by transmission electron microscopy (TEM), field-emission scanning electron microscopy (FE-SEM) and Scanning Electron Microscopy (SEM). Both differences and similarities in morphology between the samples have been discovered. In the ZnS/PbS sample, ZnS nanorods were formed with diameter less than 50 nm and length between 2000 and 3000 nm. The pure ZnS sample has dense structure and its thickness was about 200 nm. Samples were studied in detail using energy-dispersive X-ray spectroscopy (EDX). The surface chemical compositions of the samples were confirmed by means of X-ray photoelectron spectroscopy (XPS). The determination of the crystal structure using the X-ray diffraction revealed that two phases of ZnS, blende and wurtzite, are present in the sample after adding Pb, while only blende is identified in the pure ZnS sample.
In this work, the possibility of using nano-porous materials for the separation and storage of no... more In this work, the possibility of using nano-porous materials for the separation and storage of noble gases from the off-gas steam generated during the operation of nuclear reprocessing units was theoretically explored. To this end, simulations using the Grand Canonical Monte Carlo (GCMC) method were performed on a wide range of pressure to predict isothermal adsorption at the unit working temperature (323 K) and room temperature (298 K) for a gas mixture of Xe, Kr, N 2 and Ar in eight different materials, which all vary in metal ions, pore size and available surface area. This allows us to have a detailed insight at the molecular level of adsorption mechanisms. Results can be used to help designing multi-stage membrane, where only one noble gas will be captured and stored in each stage.
In this work, the storage of pure CO 2 and CH 4 gases and separation of their binary mixture in n... more In this work, the storage of pure CO 2 and CH 4 gases and separation of their binary mixture in new type of nanostructured materials called boron imidazolate frameworks (BIFs) have been investigated using atomistic simulation to provide information for material selection in adsorbent designs. Adsorption isotherms and adsorption selectivities were computed using grand canonical Monte Carlo (GCMC). Our results showed that BIFs exhibit significantly higher selectivities for separation of CO 2 from CH 4 compared to other widely studied metal organic framework (MOF) materials.
An entry from the Cambridge Structural Database, the world's repository for small molecule cr... more An entry from the Cambridge Structural Database, the world's repository for small molecule crystal structures. The entry contains experimental data from a crystal diffraction study. The deposited dataset for this entry is freely available from the CCDC and typically includes 3D coordinates, cell parameters, space group, experimental conditions and quality measures.
An entry from the Cambridge Structural Database, the world's repository for small molecule cr... more An entry from the Cambridge Structural Database, the world's repository for small molecule crystal structures. The entry contains experimental data from a crystal diffraction study. The deposited dataset for this entry is freely available from the CCDC and typically includes 3D coordinates, cell parameters, space group, experimental conditions and quality measures.
The catalytic activity and stability of metal nanocatalysts toward agglomeration and detachment d... more The catalytic activity and stability of metal nanocatalysts toward agglomeration and detachment during their preparation on a support surface are major challenges in practical applications. Herein, we report a novel, one-step, synchronized electro-oxidation-reduction "bottom-up" approach for the preparation of small and highly stable Cu nanoparticles (NPs) supported on a porous inorganic (TiO2@SiO2) coating with significant catalytic activity and stability. This unique embedded structure restrains the sintering of CuNPs on a porous TiO2@SiO2 surface at a high temperature and exhibits a high reduction ratio (100% in 60 s) and no decay in activity even after 30 cycles (>98% conversion in 3 min). This occurs in a model reaction of 4-nitrophenol (4-NP) hydrogenation, far exceeding the performance of most common catalysts observed to date. More importantly, nitroarene, ketone/aldehydes, and organic dyes were reduced to the corresponding compounds with 100% conversion. Density functional theory (DFT) calculations of experimental model systems with six Cu, two Fe, and four Ag clusters anchored on the TiO2 surface were conducted to verify the experimental observations. The experimental results and DFT calculations revealed that CuNPs not only favor the adsorption on the TiO2 surface over those of Fe and AgNPs but also boost the adsorption energy and activity of 4-NP. This strategy has also been extended to the preparation of other single-atom catalysts (e.g., FeNPs-TiO2@SiO2 and AgNPs-TiO2@SiO2), which exhibit excellent catalytic performance.
An entry from the Cambridge Structural Database, the world's repository for small molecule cr... more An entry from the Cambridge Structural Database, the world's repository for small molecule crystal structures. The entry contains experimental data from a crystal diffraction study. The deposited dataset for this entry is freely available from the CCDC and typically includes 3D coordinates, cell parameters, space group, experimental conditions and quality measures.
Practical methods for hydrogen storage are still a prime challenge in the realization of an energ... more Practical methods for hydrogen storage are still a prime challenge in the realization of an energy economy based on Hydrogen. Metal organic frameworks (MOFs) are crystalline ultra-porous materials with ability to trap and store voluminous amounts of gas molecules. MOFs represent an encouraging storage method relying on their enormous surface area. However, MOFs show reduced hydrogen uptake at room temperature due to low adsorption energy of hydrogen. To increase the adsorption uptake of MOFs at room temperature, the adsorption energy must be increased. In this contribution, materials exhibiting higher adsorption energy and enhanced hydrogen adsorption, namely MIL-53 (Al) and MOF-74, have been investigated using molecular dynamics (MD) simulation. MD simulations were performed within the density functional based tight binding method (DC-SCC-DFTB). Our results demonstrate that DC-SCC-DFTB method predicts structural parameters, adsorption sites, adsorption energies and diffusion factor...
Summary In this study structural characteristics of several carbon based nanostructures and organ... more Summary In this study structural characteristics of several carbon based nanostructures and organic frameworks as metal organic frameworks (MOF) and covalent organic frameworks (COF) on the hydrogen abundance in the material are investigated with the quantized liquid density functional theory (QLDFT), Molecular Dynamics (MD) and Grand Canonical Monte Carlo (GCMC). We applied these theories to evaluate the hydrogen storage capacities of nanoporous materials: Compact storage of hydrogen is the key challenge facing adoption of hydrogen as fuel for mobile applications. A promising approach to increase the storage densities is the adsorption of molecular hydrogen in porous environments. We have studied in detail the role of the host structure, the pressure and temperature dependence as well as the importance of quantum effects on the hydrogen storage capacity of a broad range of materials. A critical comparison with available experimental data is also given
The chemical and physical features of metal organic frameworks (MOFs) at a molecular level are of... more The chemical and physical features of metal organic frameworks (MOFs) at a molecular level are of great merit to understand structure–property relationships and, consequently, to aid in the design of improved high value products. This paper reports on the processing of one MOF-type material, namely MIL-101(Cr), by γ-ray irradiation at low doses up to 30 kGy. The optimum dose is determined to be 15 kGy, at which an increase in the adsorption of iodine of more than 40% is achieved in comparison with thermally activated un-irradiated MIL-101(Cr). Scanning electron microscopy, X-ray diffraction and the Brunauer−Emmett−Teller (BET) isotherms indicate a significant particle agglomeration and a preservation of both the unit cell topology as well as the mesoporous structure of MOF. Two-dimensional correlation Fourier transformation infrared and X-ray diffraction reveals that orientation is the driving force for structural alterations including water type, bonding and contents. These effects...
International Journal of Hydrogen Energy, May 1, 2011
A multiscale approach is used to investigate the hydrogen adsorption in nanoporous Zeolite Imidaz... more A multiscale approach is used to investigate the hydrogen adsorption in nanoporous Zeolite Imidazolate Frameworks (ZIFs) on varying geometries and organic linkers. Ab initio calculations are performed at the MP2 level to obtain correct interaction energies between hydrogen molecules and the ZIF structures. Subsequently, classical grand canonical Monte-Carlo (GCMC) simulations are carried out to obtain the hydrogen uptake of ZIFs at different thermodynamic conditions of pressure and temperature.
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Papers by Bassem Assfour