12 research outputs found
Shaping of Metal–Organic Frameworks: From Fluid to Shaped Bodies and Robust Foams
The applications
of metal–organic frameworks (MOFs) toward industrial separation,
catalysis, sensing, and some sophisticated devices are drastically
affected by their intrinsic fragility and poor processability. Unlike
organic polymers, MOF crystals are insoluble in any solvents and are
usually not thermoplastic, which means traditional solvent- or melting-based
processing techniques are not applicable for MOFs. Herein, a continuous
phase transformation processing strategy is proposed for fabricating
and shaping MOFs into processable fluids, shaped bodies, and even
MOF foams that are capable of reversible transformation among these
states. Based on this strategy, a cup-shaped Cu-MOF composite and
hierarchically porous MOF foam were developed for highly efficient
catalytic C–H oxidation (conv. 76% and sele. 93% for cup-shaped
Cu-MOF composite and conv. 92% and sele. 97% for porous foam) with
ease of recycling and dramatically improved kinetics. Furthermore,
various MOF-based foams with low densities (<0.1 g cm<sup>–3</sup>) and high MOF loadings (up to 80 wt %) were obtained via this protocol.
Imparted with hierarchically porous structures and fully accessible
MOFs uniformly distributed, these foams presented low energy penalty
(pressure drop <20 Pa, at 500 mL min<sup>–1</sup>) and showed
potential applications as efficient membrane reactors
In Situ Growth of MOFs on the Surface of Si Nanoparticles for Highly Efficient Lithium Storage: Si@MOF Nanocomposites as Anode Materials for Lithium-Ion Batteries
A simple
yet powerful one-pot strategy is developed to prepare
metal–organic framework-coated silicon nanoparticles via in
situ mechanochemical synthesis. After simple pyrolysis, the thus-obtained
composite shows exceptional electrochemical properties with a lithium
storage capacity up to 1050 mA h g<sup>–1</sup>, excellent
cycle stability (>99% capacity retention after 500 cycles) and
outstanding
rate performance. These characteristics, combined with their high
stability and ease of fabrication, make such Si@MOF nanocomposites
ideal alternative candidates as high-energy anode materials in lithium-ion
batteries
Modulated Connection Modes of Redox Units in Molecular Junction Covalent Organic Frameworks for Artificial Photosynthetic Overall Reaction
The precise tuning of components, spatial orientations,
or connection
modes for redox units is vital for gaining deep insight into efficient
artificial photosynthetic overall reaction, yet it is still hard achieve
for heterojunction photocatalysts. Here, we have developed a series
of redox molecular junction covalent organic frameworks (COFs) (M-TTCOF-Zn, M = Bi, Tri, and Tetra) for artificial photosynthetic
overall reaction. The covalent connection between TAPP-Zn and multidentate
TTF endows various connection modes between water photo-oxidation
(multidentate TTF) and CO2 photoreduction (TAPP-Zn) centers
that can serve as desired platforms to study the possible interactions
between redox centers. Notably, Bi-TTCOF-Zn exhibits
a high CO production rate of 11.56 μmol g–1 h–1 (selectivity, ∼100%), which is more
than 2 and 6 times higher than those of Tri-TTCOF-Zn and Tetra-TTCOF-Zn, respectively. As revealed by theoretical calculations, Bi-TTCOF-Zn facilitates a more uniform distribution of energy-level
orbitals, faster charge transfer, and stronger *OH adsorption/stabilization
ability than those of Tri-TTCOF-Zn and Tetra-TTCOF-Zn
Modulated Connection Modes of Redox Units in Molecular Junction Covalent Organic Frameworks for Artificial Photosynthetic Overall Reaction
The precise tuning of components, spatial orientations,
or connection
modes for redox units is vital for gaining deep insight into efficient
artificial photosynthetic overall reaction, yet it is still hard achieve
for heterojunction photocatalysts. Here, we have developed a series
of redox molecular junction covalent organic frameworks (COFs) (M-TTCOF-Zn, M = Bi, Tri, and Tetra) for artificial photosynthetic
overall reaction. The covalent connection between TAPP-Zn and multidentate
TTF endows various connection modes between water photo-oxidation
(multidentate TTF) and CO2 photoreduction (TAPP-Zn) centers
that can serve as desired platforms to study the possible interactions
between redox centers. Notably, Bi-TTCOF-Zn exhibits
a high CO production rate of 11.56 μmol g–1 h–1 (selectivity, ∼100%), which is more
than 2 and 6 times higher than those of Tri-TTCOF-Zn and Tetra-TTCOF-Zn, respectively. As revealed by theoretical calculations, Bi-TTCOF-Zn facilitates a more uniform distribution of energy-level
orbitals, faster charge transfer, and stronger *OH adsorption/stabilization
ability than those of Tri-TTCOF-Zn and Tetra-TTCOF-Zn
Modulated Connection Modes of Redox Units in Molecular Junction Covalent Organic Frameworks for Artificial Photosynthetic Overall Reaction
The precise tuning of components, spatial orientations,
or connection
modes for redox units is vital for gaining deep insight into efficient
artificial photosynthetic overall reaction, yet it is still hard achieve
for heterojunction photocatalysts. Here, we have developed a series
of redox molecular junction covalent organic frameworks (COFs) (M-TTCOF-Zn, M = Bi, Tri, and Tetra) for artificial photosynthetic
overall reaction. The covalent connection between TAPP-Zn and multidentate
TTF endows various connection modes between water photo-oxidation
(multidentate TTF) and CO2 photoreduction (TAPP-Zn) centers
that can serve as desired platforms to study the possible interactions
between redox centers. Notably, Bi-TTCOF-Zn exhibits
a high CO production rate of 11.56 μmol g–1 h–1 (selectivity, ∼100%), which is more
than 2 and 6 times higher than those of Tri-TTCOF-Zn and Tetra-TTCOF-Zn, respectively. As revealed by theoretical calculations, Bi-TTCOF-Zn facilitates a more uniform distribution of energy-level
orbitals, faster charge transfer, and stronger *OH adsorption/stabilization
ability than those of Tri-TTCOF-Zn and Tetra-TTCOF-Zn
Modulated Connection Modes of Redox Units in Molecular Junction Covalent Organic Frameworks for Artificial Photosynthetic Overall Reaction
The precise tuning of components, spatial orientations,
or connection
modes for redox units is vital for gaining deep insight into efficient
artificial photosynthetic overall reaction, yet it is still hard achieve
for heterojunction photocatalysts. Here, we have developed a series
of redox molecular junction covalent organic frameworks (COFs) (M-TTCOF-Zn, M = Bi, Tri, and Tetra) for artificial photosynthetic
overall reaction. The covalent connection between TAPP-Zn and multidentate
TTF endows various connection modes between water photo-oxidation
(multidentate TTF) and CO2 photoreduction (TAPP-Zn) centers
that can serve as desired platforms to study the possible interactions
between redox centers. Notably, Bi-TTCOF-Zn exhibits
a high CO production rate of 11.56 μmol g–1 h–1 (selectivity, ∼100%), which is more
than 2 and 6 times higher than those of Tri-TTCOF-Zn and Tetra-TTCOF-Zn, respectively. As revealed by theoretical calculations, Bi-TTCOF-Zn facilitates a more uniform distribution of energy-level
orbitals, faster charge transfer, and stronger *OH adsorption/stabilization
ability than those of Tri-TTCOF-Zn and Tetra-TTCOF-Zn
Modulated Connection Modes of Redox Units in Molecular Junction Covalent Organic Frameworks for Artificial Photosynthetic Overall Reaction
The precise tuning of components, spatial orientations,
or connection
modes for redox units is vital for gaining deep insight into efficient
artificial photosynthetic overall reaction, yet it is still hard achieve
for heterojunction photocatalysts. Here, we have developed a series
of redox molecular junction covalent organic frameworks (COFs) (M-TTCOF-Zn, M = Bi, Tri, and Tetra) for artificial photosynthetic
overall reaction. The covalent connection between TAPP-Zn and multidentate
TTF endows various connection modes between water photo-oxidation
(multidentate TTF) and CO2 photoreduction (TAPP-Zn) centers
that can serve as desired platforms to study the possible interactions
between redox centers. Notably, Bi-TTCOF-Zn exhibits
a high CO production rate of 11.56 μmol g–1 h–1 (selectivity, ∼100%), which is more
than 2 and 6 times higher than those of Tri-TTCOF-Zn and Tetra-TTCOF-Zn, respectively. As revealed by theoretical calculations, Bi-TTCOF-Zn facilitates a more uniform distribution of energy-level
orbitals, faster charge transfer, and stronger *OH adsorption/stabilization
ability than those of Tri-TTCOF-Zn and Tetra-TTCOF-Zn
Interpenetrating 3D Covalent Organic Framework for Selective Stilbene Photoisomerization and Photocyclization
The
selective photoisomerization or photocyclization
of stilbene
to achieve value upgrade is of great significance in industry applications,
yet it remains a challenge to accomplish both of them through a one-pot
photocatalysis strategy under mild conditions. Here, a sevenfold interpenetrating
3D covalent organic framework (TPDT-COF) has been synthesized
through covalent coupling between N,N,N,N-tetrakis(4-aminophenyl)-1,4-benzenediamine
(light absorption and free radical generation) and 5,5′-(2,1,3-benzothiadiazole-4,7-diyl)bis[2-thiophenecarboxaldehyde]
(catalytic center). The thus-obtained sevenfold interpenetrating structure
presents a functional pore channel with a tunable photocatalytic ability
and specific pore confinement effect that can be applied for selective
stilbene photoisomerization and photocyclization. Noteworthily, it
enables photogeneration of cis-stilbene or phenanthrene
with >99% selectivity by simply changing the gas atmosphere under
mild conditions (Ar, SeleCis. > 99%, SelePhen. 2, SeleCis. Phen. > 99%). Theoretical calculations prove that different
gas atmospheres possess varying influences on the energy barriers
of reaction intermediates, and the pore confinement effect plays a
synergistically catalytic role, thus inducing different product generation.
This study might facilitate the exploration of porous crystalline
materials in selective photoisomerization and photocyclization
Modulated Connection Modes of Redox Units in Molecular Junction Covalent Organic Frameworks for Artificial Photosynthetic Overall Reaction
The precise tuning of components, spatial orientations,
or connection
modes for redox units is vital for gaining deep insight into efficient
artificial photosynthetic overall reaction, yet it is still hard achieve
for heterojunction photocatalysts. Here, we have developed a series
of redox molecular junction covalent organic frameworks (COFs) (M-TTCOF-Zn, M = Bi, Tri, and Tetra) for artificial photosynthetic
overall reaction. The covalent connection between TAPP-Zn and multidentate
TTF endows various connection modes between water photo-oxidation
(multidentate TTF) and CO2 photoreduction (TAPP-Zn) centers
that can serve as desired platforms to study the possible interactions
between redox centers. Notably, Bi-TTCOF-Zn exhibits
a high CO production rate of 11.56 μmol g–1 h–1 (selectivity, ∼100%), which is more
than 2 and 6 times higher than those of Tri-TTCOF-Zn and Tetra-TTCOF-Zn, respectively. As revealed by theoretical calculations, Bi-TTCOF-Zn facilitates a more uniform distribution of energy-level
orbitals, faster charge transfer, and stronger *OH adsorption/stabilization
ability than those of Tri-TTCOF-Zn and Tetra-TTCOF-Zn
Modulated Connection Modes of Redox Units in Molecular Junction Covalent Organic Frameworks for Artificial Photosynthetic Overall Reaction
The precise tuning of components, spatial orientations,
or connection
modes for redox units is vital for gaining deep insight into efficient
artificial photosynthetic overall reaction, yet it is still hard achieve
for heterojunction photocatalysts. Here, we have developed a series
of redox molecular junction covalent organic frameworks (COFs) (M-TTCOF-Zn, M = Bi, Tri, and Tetra) for artificial photosynthetic
overall reaction. The covalent connection between TAPP-Zn and multidentate
TTF endows various connection modes between water photo-oxidation
(multidentate TTF) and CO2 photoreduction (TAPP-Zn) centers
that can serve as desired platforms to study the possible interactions
between redox centers. Notably, Bi-TTCOF-Zn exhibits
a high CO production rate of 11.56 μmol g–1 h–1 (selectivity, ∼100%), which is more
than 2 and 6 times higher than those of Tri-TTCOF-Zn and Tetra-TTCOF-Zn, respectively. As revealed by theoretical calculations, Bi-TTCOF-Zn facilitates a more uniform distribution of energy-level
orbitals, faster charge transfer, and stronger *OH adsorption/stabilization
ability than those of Tri-TTCOF-Zn and Tetra-TTCOF-Zn