scholarly journals Catching the Reversible Formation and Reactivity of Surface Defective Sites in Metal–Organic Frameworks: An Operando Ambient Pressure-NEXAFS Investigation

2021 ◽  
Vol 12 (37) ◽  
pp. 9182-9187
Author(s):  
Luca Braglia ◽  
Francesco Tavani ◽  
Silvia Mauri ◽  
Raju Edla ◽  
Damjan Krizmancic ◽  
...  
Keyword(s):  
Ambient Pressure ◽  
Metal Organic Frameworks ◽  
Metal Organic ◽  
Reversible Formation ◽  
Defective Sites

scholarly journals Band Gap Modulation in Zirconium-Based Metal-Organic Frameworks by Defect Engineering

2019 ◽  
Author(s):  
Marco Taddei ◽  
Giulia M. Schukraft ◽  
Michael E. A. Warwick ◽  
Davide Tiana ◽  
Matthew McPherson ◽  
...  
Keyword(s):  
Band Gap ◽  
Gas Phase ◽  
Metal Organic Framework ◽  
Metal Organic Frameworks ◽  
Benzoic Acids ◽  
Defect Engineering ◽  
Metal Organic ◽  
Band Gap Modulation ◽  
Valence Band Energy ◽  
Defective Sites

We report a defect-engineering approach to modulate the band gap of zirconium-based metal-organic framework UiO-66, enabled by grafting of a range of amino-functionalised benzoic acids at defective sites. Defect engineered MOFs were obtained by both post-synthetic exchange and modulated synthesis, featuring band gap in the 4.1-3.3 eV range. Ab-initio calculations suggest that shrinking of the band gap is mainly due to an upward shift of the valence band energy, as a result of the presence of light-absorbing monocarboxylates. The photocatalytic properties of defect-engineered MOFs towards CO<sub>2</sub> reduction to CO in the gas phase and degradation of Rhodamine B in water were tested, observing improved activity in both cases, in comparison to a defective UiO-66 bearing formic acid as the defect-compensating species.

scholarly journals Band Gap Modulation in Zirconium-Based Metal-Organic Frameworks by Defect Engineering

2019 ◽  
Author(s):  
Marco Taddei ◽  
Giulia M. Schukraft ◽  
Michael E. A. Warwick ◽  
Davide Tiana ◽  
Matthew McPherson ◽  
...  
Keyword(s):  
Band Gap ◽  
Gas Phase ◽  
Metal Organic Framework ◽  
Metal Organic Frameworks ◽  
Benzoic Acids ◽  
Defect Engineering ◽  
Metal Organic ◽  
Band Gap Modulation ◽  
Valence Band Energy ◽  
Defective Sites

We report a defect-engineering approach to modulate the band gap of zirconium-based metal-organic framework UiO-66, enabled by grafting of a range of amino-functionalised benzoic acids at defective sites. Defect engineered MOFs were obtained by both post-synthetic exchange and modulated synthesis, featuring band gap in the 4.1-3.3 eV range. Ab-initio calculations suggest that shrinking of the band gap is mainly due to an upward shift of the valence band energy, as a result of the presence of light-absorbing monocarboxylates. The photocatalytic properties of defect-engineered MOFs towards CO<sub>2</sub> reduction to CO in the gas phase and degradation of Rhodamine B in water were tested, observing improved activity in both cases, in comparison to a defective UiO-66 bearing formic acid as the defect-compensating species.

scholarly journals Pressure Promoted Low-Temperature Melting of Metal-Organic Frameworks

2018 ◽  
Author(s):  
Remo N. Widmer ◽  
Giulio I. Lampronti ◽  
Simone Anzellini ◽  
Romain Gaillac ◽  
Stefan Farsang ◽  
...  
Keyword(s):  
High Pressure ◽  
Elevated Temperatures ◽  
Ambient Pressure ◽  
Metal Organic Frameworks ◽  
Temperature Phase ◽  
Guest Molecules ◽  
Complex Behaviour ◽  
Metal Organic ◽  
The Stability ◽  
Liquid States

Metal-organic frameworks (MOFs) are microporous materials with huge potential as host structures for chemical processes, including retention, catalytic reaction, or separation of guest molecules. Structural collapse at high-pressure, and unusual behaviours at elevated temperatures, such as melting and transitions to liquid states, have recently been observed in the family. Here, we show that the effect of the application of simultaneous high-pressure and -temperature on a MOF can be understood in terms of silicate analogues, with crystalline, amorphous and liquid states occurring across the pressure - temperature phase diagram. The response of ZIF-62, the MOF on which we focus, to simultaneous pressure and temperature reveals a complex behaviour with distinct high- and low- density amorphous phases occurring over different regions of the pressure-temperature space. In-situ powder X-ray diffraction, Raman spectroscopy and optical microscopy reveal that the stability of the liquid MOF-state expands significantly towards lower temperatures at intermediate, industrially achievable pressures. Our results imply a novel route to the synthesis of functional MOF glasses at low temperatures, avoiding decomposition upon heating at ambient pressure.

scholarly journals Templated fabrication of hierarchically porous metal–organic frameworks and simulation of crystal growth

2019 ◽  
Vol 1 (3) ◽  
pp. 1062-1069 ◽  
Author(s):  
Chongxiong Duan ◽  
Hang Zhang ◽  
Minhui Yang ◽  
Feier Li ◽  
Yi Yu ◽  
...  
Keyword(s):  
Crystal Growth ◽  
Growth Mechanism ◽  
Room Temperature ◽  
Ambient Pressure ◽  
Metal Organic Frameworks ◽  
Porous Metal ◽  
Double Salt ◽  
Hierarchically Porous ◽  
Metal Organic

Hierarchically porous MOF materials were rapidly synthesized in a (Cu, Zn) hydroxy double salt (HDS) solution using a novel surfactant as template at room temperature and ambient pressure, and their growth mechanism was disclosed via mesodynamics (MesoDyn) simulation.

Establishing upper bounds on CO2 swing capacity in sub-ambient pressure swing adsorption via molecular simulation of metal–organic frameworks

2017 ◽  
Vol 5 (24) ◽  
pp. 12258-12265 ◽  
Author(s):  
Jongwoo Park ◽  
Ryan P. Lively ◽  
David S. Sholl
Keyword(s):  
Molecular Simulation ◽  
Pressure Swing Adsorption ◽  
Ambient Pressure ◽  
Metal Organic Frameworks ◽  
Upper Bounds ◽  
Nanoporous Materials ◽  
Metal Organic ◽  
Pressure Swing

Nanoporous materials are identified with CO2 swing capacities up to 40 mol kg−1 using a pressure swing from 0.1 bar to 2.0 bar at subambient conditions.

scholarly journals Band Gap Modulation in Zirconium-Based Metal-Organic Frameworks by Defect Engineering

2019 ◽  
Author(s):  
Marco Taddei ◽  
Giulia M. Schukraft ◽  
Michael E. A. Warwick ◽  
Davide Tiana ◽  
Matthew McPherson ◽  
...  
Keyword(s):  
Band Gap ◽  
Gas Phase ◽  
Metal Organic Framework ◽  
Metal Organic Frameworks ◽  
Benzoic Acids ◽  
Defect Engineering ◽  
Metal Organic ◽  
Band Gap Modulation ◽  
Valence Band Energy ◽  
Defective Sites

We report a defect-engineering approach to modulate the band gap of zirconium-based metal-organic framework UiO-66, enabled by grafting of a range of amino-functionalised benzoic acids at defective sites. Defect engineered MOFs were obtained by both post-synthetic exchange and modulated synthesis, featuring band gap in the 4.1-3.3 eV range. Ab-initio calculations suggest that shrinking of the band gap is mainly due to an upward shift of the valence band energy, as a result of the presence of light-absorbing monocarboxylates. The photocatalytic properties of defect-engineered MOFs towards CO<sub>2</sub> reduction to CO in the gas phase and degradation of Rhodamine B in water were tested, observing improved activity in both cases, in comparison to a defective UiO-66 bearing formic acid as the defect-compensating species.

scholarly journals Pressure Promoted Low-Temperature Melting of Metal-Organic Frameworks

2018 ◽  
Author(s):  
Remo N. Widmer ◽  
Giulio I. Lampronti ◽  
Simone Anzellini ◽  
Romain Gaillac ◽  
Stefan Farsang ◽  
...  
Keyword(s):  
High Pressure ◽  
Elevated Temperatures ◽  
Ambient Pressure ◽  
Metal Organic Frameworks ◽  
Temperature Phase ◽  
Guest Molecules ◽  
Complex Behaviour ◽  
Metal Organic ◽  
The Stability ◽  
Liquid States

Metal-organic frameworks (MOFs) are microporous materials with huge potential as host structures for chemical processes, including retention, catalytic reaction, or separation of guest molecules. Structural collapse at high-pressure, and unusual behaviours at elevated temperatures, such as melting and transitions to liquid states, have recently been observed in the family. Here, we show that the effect of the application of simultaneous high-pressure and -temperature on a MOF can be understood in terms of silicate analogues, with crystalline, amorphous and liquid states occurring across the pressure - temperature phase diagram. The response of ZIF-62, the MOF on which we focus, to simultaneous pressure and temperature reveals a complex behaviour with distinct high- and low- density amorphous phases occurring over different regions of the pressure-temperature space. In-situ powder X-ray diffraction, Raman spectroscopy and optical microscopy reveal that the stability of the liquid MOF-state expands significantly towards lower temperatures at intermediate, industrially achievable pressures. Our results imply a novel route to the synthesis of functional MOF glasses at low temperatures, avoiding decomposition upon heating at ambient pressure.

scholarly journals Computational Screening of Roles of Defects and Metal Substitution on Reactivity of Different Single- vs Double-Node Metal–Organic Frameworks for Sarin Decomposition

2019 ◽  
Author(s):  
MohammadReza MomeniTaheri ◽  
Christopher J. Cramer
Keyword(s):  
Heterogeneous Catalysts ◽  
Metal Organic Frameworks ◽  
Chemical Warfare Agent ◽  
Metal Substitution ◽  
Heterogeneous Catalytic ◽  
Computational Screening ◽  
Periodic Models ◽  
Metal Organic ◽  
Hydrolysis Of ◽  
Defective Sites

Understanding how different factors affect the electronic prop-erties of metal-organic frameworks (MOFs) is critical to under-standing their potential for catalysis and to serve as catalyst supports. In this work, periodic dispersion corrected PBE cal-culations are performed to assess the catalytic activity of dif-ferent Zr6 vs Zr12 metal-organic frameworks (MOFs) for the heterogeneous catalytic hydrolysis of the chemical warfare agent (CWA) sarin. Using a comprehensive series of extended periodic models capable of capturing long-range sar-in/water/framework interactions in both Zr6 and Zr12 MOFs, the effect of numbers and morphologies of defective sites as well as ZrIV substitution with heavier CeIV are thoroughly in-vestigated. Our calculations show that hydrogen bonds in-volving both metal-oxide nodes and organic linkers can play important roles in the catalysis. Insights derived from this work should inform the design and realization of more effec-tive and robust next-generation MOF-based heterogeneous catalysts.

scholarly journals Computational Screening of Roles of Defects and Metal Substitution on Reactivity of Different Single- vs Double-Node Metal–Organic Frameworks for Sarin Decomposition

2019 ◽  
Author(s):  
MohammadReza MomeniTaheri ◽  
Christopher J. Cramer
Keyword(s):  
Heterogeneous Catalysts ◽  
Metal Organic Frameworks ◽  
Chemical Warfare Agent ◽  
Metal Substitution ◽  
Heterogeneous Catalytic ◽  
Computational Screening ◽  
Periodic Models ◽  
Metal Organic ◽  
Hydrolysis Of ◽  
Defective Sites

Understanding how different factors affect the electronic prop-erties of metal-organic frameworks (MOFs) is critical to under-standing their potential for catalysis and to serve as catalyst supports. In this work, periodic dispersion corrected PBE cal-culations are performed to assess the catalytic activity of dif-ferent Zr6 vs Zr12 metal-organic frameworks (MOFs) for the heterogeneous catalytic hydrolysis of the chemical warfare agent (CWA) sarin. Using a comprehensive series of extended periodic models capable of capturing long-range sar-in/water/framework interactions in both Zr6 and Zr12 MOFs, the effect of numbers and morphologies of defective sites as well as ZrIV substitution with heavier CeIV are thoroughly in-vestigated. Our calculations show that hydrogen bonds in-volving both metal-oxide nodes and organic linkers can play important roles in the catalysis. Insights derived from this work should inform the design and realization of more effec-tive and robust next-generation MOF-based heterogeneous catalysts.

scholarly journals Pressure Promoted Low-Temperature Melting of Metal-Organic Frameworks

2018 ◽  
Author(s):  
Remo N. Widmer ◽  
Giulio I. Lampronti ◽  
Simone Anzellini ◽  
Romain Gaillac ◽  
Stefan Farsang ◽  
...  
Keyword(s):  
High Pressure ◽  
Elevated Temperatures ◽  
Ambient Pressure ◽  
Metal Organic Frameworks ◽  
Temperature Phase ◽  
Guest Molecules ◽  
Complex Behaviour ◽  
Metal Organic ◽  
The Stability ◽  
Liquid States

Metal-organic frameworks (MOFs) are microporous materials with huge potential as host structures for chemical processes, including retention, catalytic reaction, or separation of guest molecules. Structural collapse at high-pressure, and unusual behaviours at elevated temperatures, such as melting and transitions to liquid states, have recently been observed in the family. Here, we show that the effect of the application of simultaneous high-pressure and -temperature on a MOF can be understood in terms of silicate analogues, with crystalline, amorphous and liquid states occurring across the pressure - temperature phase diagram. The response of ZIF-62, the MOF on which we focus, to simultaneous pressure and temperature reveals a complex behaviour with distinct high- and low- density amorphous phases occurring over different regions of the pressure-temperature space. In-situ powder X-ray diffraction, Raman spectroscopy and optical microscopy reveal that the stability of the liquid MOF-state expands significantly towards lower temperatures at intermediate, industrially achievable pressures. Our results imply a novel route to the synthesis of functional MOF glasses at low temperatures, avoiding decomposition upon heating at ambient pressure.

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