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1.
ACS Appl Mater Interfaces ; 14(18): 21050-21058, 2022 May 11.
Artigo em Inglês | MEDLINE | ID: mdl-35476406

RESUMO

Photocatalytic CO2 reduction is one of the most cost-effective and environmentally friendly techniques of converting CO2 into high-value compounds and/or fuels. However, the performance of most current photocatalytic CO2 reduction catalysts is less than satisfactory for practical applications. Here, we synthesized a heterogeneous structure by integrating Cu2O and a porphyrin hydrogen-bonded organic framework (PFC-45), which was then fabricated into a thin-film catalyst on carbolic paper (CP) using a facile electrophoretic deposition technology. With improved electron-hole separation efficiency and visible-light-harvesting ability, this film (PFC-45/Cu2O@CP) significantly enhanced CO2-to-CO photoreduction, exceeding 2.4 and 3.2 times that of PFC-45@CP and PFC-45/Cu2O particles, respectively. Remarkably, PFC-45/Cu2O@CP also exhibited high selectivity (99%) and outstanding activity (11.81 µmol g-1 h-1) for photocatalytic CO2 reduction in pure water without any sacrificial agent. This work demonstrates a new strategy to design photocatalysts for efficient CO2 reduction.

2.
Angew Chem Int Ed Engl ; : e202203955, 2022 Apr 19.
Artigo em Inglês | MEDLINE | ID: mdl-35441462

RESUMO

In natural photosynthesis, the architecture of multiproteins integrates more chromophores than redox centers and simultaneously creates a well-controlled environment around the active site. Herein, we demonstrate that these features can be emulated in a prototype hydrogen-bonded organic framework (HOF) through simply varying the proportion of metalated porphyrin in the structure. Further studies demonstrate that changing the metalloporphyrin content not only realizes a fine tuning of the photosensitizer/catalyst ratio, but also alters the microenvironment surrounding the active site and the charge separation efficiency. As a result, the obtained material achieves the challenging overall CO2 reduction with a high HCOOH production rate (29.8 µmol g-1 h-1 , scavenger free), standing out from existing competitors. This work unveils that the degree of metalation is vital to the catalytic activity of the porphryinic framework, presenting as a new strategy to optimize the performance of heterogeneous catalysts.

3.
Small ; 18(16): e2200407, 2022 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-35266311

RESUMO

Previous studies on syntheses of metal-organic frameworks (MOFs) for photocatalytic CO2 reduction are mainly focused on the exquisite control over the net topology and the functionality of metal clusters/organic building blocks. This contribution demonstrates that the rational design of MOF-based photocatalyst can be further extended to the hierarchical structure at micrometer scales well beyond the conventional MOF design at the molecular level. By taking advantage of the disparity of two selective MOFs in nucleation kinetics, a hierarchical core-shell MOF@MOF structure is successfully constructed through a simple one-pot synthesis. Besides inheriting the high porosity, crystallinity, and robustness of parent MOFs, the obtained heterojunction exhibits extended photoresponse, optimized band alignment with large overpotential, and greatly enhanced photogenerated charge separation, which would be hardly realized by the merely molecular-level assembly. As a result, the challenging overall CO2 photoreduction is achieved, which generates a record high HCOOH production (146.0 µmol/g/h) without using any sacrificial reagents. Moreover, the core-shell structure exhibits a more effective use of photogenerated electrons than the individual MOFs. This work shows that harnessing the hierarchical architecture of MOFs present a new and effective alternative to tuning the photocatalytic performance at a mesoscopic level.

4.
Angew Chem Int Ed Engl ; 61(6): e202115854, 2022 Feb 01.
Artigo em Inglês | MEDLINE | ID: mdl-34877789

RESUMO

Under topological guidance, the self-assembly process based on a tetratopic porphyrin synthon results in a hydrogen-bonded organic framework (HOF) with the predicted square layers topology (sql) but unsatisfied stability. Strikingly, simply introducing a transition metal in the porphyrin center does not change the network topology but drastically causes noticeable change on noncovalent interaction, orbital overlap, and molecular geometry, therefore ultimately giving rise to a series of metalloporphyrinic HOFs with high surface area, and excellent stability (intact after being soaked in boiling water, concentrated HCl, and heated to 270 °C). On integrating both photosensitizers and catalytic sites into robust backbones, this series of HOFs can effectively catalyze the photoreduction of CO2 to CO, and their catalytic performances greatly depend on the chelated metal species in the porphyrin centers. This work enriches the library of stable functional HOFs and expands their applications in photocatalytic CO2 reduction.

5.
Chemistry ; 27(42): 10957-10965, 2021 Jul 26.
Artigo em Inglês | MEDLINE | ID: mdl-33884685

RESUMO

Porous materials have been investigated as efficient photochromic platforms for detecting hazardous radiation, while the utilization of hydrogen bonded organic frameworks (HOFs) in this field has remained intact. Herein, two HOFs were synthesized through self-assembly of tetratopic viologen ligand and formic acid (PFC-25, PFC-26), as a new class of "all-organic" radiochromic smart material, opening a gate for HOFs in this field. PFC-26 is active upon both X-ray and UV irradiation, while PFC-25 is only active upon X-ray irradiation. The same building block yet different radiochromic behaviors of PFC-25 and PFC-26 allow us to gain a deep mechanistic understanding of the factors that control the detection specificity. Theoretical and experimental studies reveal that the degree of π-conjugation of viologen ligand is highly related to the threshold energy of triggering a charge transfer, therefore being a vital factor for the particularity of radiochromic materials. Thanks to its convenient processibility, nanoparticle size, and UV silence, PFC-25 can be further fabricated into a portable naked-eye sensor for X-ray detection, which shows obvious color change with the merits of high transmittance contrast, good sensitivity (reproducible dose threshold of 3.5 Gy), and excellent stability. The work exhibits the promising practical potentials of HOF materials in photochromic technology.


Assuntos
Hidrogênio , Viologênios , Ligação de Hidrogênio , Raios X
6.
J Am Chem Soc ; 142(28): 12515-12523, 2020 Jul 15.
Artigo em Inglês | MEDLINE | ID: mdl-32564596

RESUMO

The recombination of electron-hole pairs severely detracts from the efficiency of photocatalysts. This issue could be addressed in metal-organic frameworks (MOFs) through optimization of the charge-transfer kinetics via rational design of structures at atomic level. Herein, a pyrazolyl porphyrinic Ni-MOF (PCN-601), integrating light harvesters, active catalytic sites, and high surface areas, has been demonstrated as a superior and durable photocatalyst for visible-light-driven overall CO2 reduction with H2O vapor at room temperature. Kinetic studies reveal that the robust coordination spheres of pyrazolyl groups and Ni-oxo clusters endow PCN-601 with proper energy band alignment and ultrafast ligand-to-node electron transfer. Consequently, the CO2-to-CH4 production rate of PCN-601 far exceeds those of the analogous MOFs based on carboxylate porphyrin and the classic Pt/CdS photocatalyst by more than 3- and 20-fold, respectively. The reaction avoids the use of hole scavengers and proceeds in a gaseous phase which can take full advantage of the high gas uptake of MOFs. This work demonstrates that the rational design of coordination spheres in MOF structures not only reconciles the contradiction between reactivity and stability but also greatly promotes the interfacial charge transfer to achieve optimized kinetics, providing guidance for the design of highly efficient MOF photocatalysts.

7.
Chem Commun (Camb) ; 56(54): 7459-7462, 2020 Jul 07.
Artigo em Inglês | MEDLINE | ID: mdl-32495788

RESUMO

A facile method, post-synthetic exchange of modulators (PSEm), has been demonstrated here to prepare chiral metal-organic frameworks for enantioseparation. Based on this method, three chiral porous Zr-based metal-organic frameworks have been prepared through exchanging the coordinated modulators on metal clusters of MOFs with commercially available chiral carboxylic acid molecules. In addition, the obtained materials show enantioselectivity toward three different enantiomers, which presents a proof of concept for the design of MOF materials for enantioseparation by an easy and low-cost method.

8.
J Am Chem Soc ; 142(15): 7218-7224, 2020 Apr 15.
Artigo em Inglês | MEDLINE | ID: mdl-32212652

RESUMO

Hydrogen-bonded organic frameworks (HOFs) show great potential in many applications, but few structure-property correlations have been explored in this field. In this work, we report that self-assembly of a rigid and planar ligand gives rise to flat hexagonal honeycomb motifs which are extended into undulated two-dimensional (2D) layers and finally generate three polycatenated HOFs with record complexity. This kind of undulation is absent in the 2D layers built from a very similar but nonplanar ligand, indicating that a slight torsion of ligand produces overwhelming structural change. This change delivers materials with unique stepwise adsorption behaviors under a certain pressure originating from the movement between mutually interwoven hexagonal networks. Meanwhile, high chemical stability, phase transformation, and preferential adsorption of aromatic compounds were observed in these HOFs. The results presented in this work would help us to understand the self-assembly behaviors of HOFs and shed light on the rational design of HOF materials for practical applications.

9.
Angew Chem Int Ed Engl ; 59(11): 4385-4390, 2020 Mar 09.
Artigo em Inglês | MEDLINE | ID: mdl-31943675

RESUMO

Although many ionic metal-organic frameworks (MOFs) have been reported, little is known about how the charge of the skeleton affects the properties of the MOF materials. Herein we report how the chemical stability of MOFs can be substantially improved through embedding electrostatic interactions in structure. A MOF with a cationic skeleton is impervious to extremely acidic, oxidative, reductive, and high ionic strength conditions, such as 12 m HCl (301 days), aqua regia (86 days), H2 O2 (30 days), and seawater (30 days), which is unprecedented for MOFs. DFT calculations suggested that steric hinderance and the repulsive interaction of the cationic framework toward positively charged species in microenvironments protects the vulnerable bonds in the structure. Diverse functionalities can be bestowed by substituting the counterions of the charged framework with identically charged functional species, which broadens the horizon in the design of MOFs adaptable to a demanding environment with specific functionalities.

10.
Nanoscale ; 11(18): 9085-9090, 2019 May 09.
Artigo em Inglês | MEDLINE | ID: mdl-31026013

RESUMO

Ultrathin semiconductors have been proposed as an excellent platform to promote solar conversion due to their ultra-large specific surface area and unique surface structures. So far, the researchers designed and constructed some multi-component heterostructure photocatalysts, but they are still unable to avoid the recombination of photoexcited electron-hole pairs. This study introduces a built-in electric field in a one-component nanosheet to promote photo-generated carrier separation. For this reason, CdS nanosheets with both photocatalytic and piezoelectric properties were selected as research objects. The combination of these two properties renders CdS an excellent candidate for efficiently utilizing both light and vibrational energy for photocatalytic water splitting, without the need for coupling it to other materials or using an external bias. The result shows that the photocatalytic and piezoelectric coupling effect of CdS can make hydrogen production reach 633 µL h-1, which was more than twice the superposition of light and vibration. The development of this coupling effect contributes to the application of green energies, such as the use of natural sunlight and noise or vibration.

11.
Biosens Bioelectron ; 31(1): 439-44, 2012 Jan 15.
Artigo em Inglês | MEDLINE | ID: mdl-22143073

RESUMO

We have developed a biomimetic sensor for the detection of human immunodeficiency virus type 1 (HIV-1) related protein (glycoprotein 41, gp41) based on epitope imprinting technique. gp41 is the transmembrane protein of HIV-1 and plays an important role in membrane fusion between viruses and infected cells. It is an important index for determining the extent of HIV-1 disease progression and the efficacy of therapeutic intervention. In this work, dopamine was used as the functional monomer and polymerized on the surface of quartz crystal microbalance (QCM) chip in the presence of template, a synthetic peptide with 35 amino acid residues, analogous to residues 579-613 of the gp41. This process resulted in grafting a hydrophilic molecularly imprinted polymer (MIP) film on the QCM chip. QCM measurement showed that the resulting MIP film not only had a great affinity towards the template peptide, but also could bind the corresponding gp41 protein specifically. The dissociation constant (K(d)) of MIP for the template peptide was calculated to be 3.17 nM through Scatchard analysis, which was similar to those of monoclonal antibodies. Direct detection of the gp41 was achieved quantitatively using the resulting MIP-based biomimetic sensor. The detection limit of gp41 was 2 ng/mL, which was comparable to the reported ELISA method. In addition, the practical analytical performance of the sensor was examined by evaluating the detection of gp41 in human urine samples with satisfactory results.


Assuntos
Técnicas Biossensoriais/instrumentação , Mapeamento de Epitopos/instrumentação , Proteína gp41 do Envelope de HIV/análise , Sistemas Microeletromecânicos/instrumentação , Impressão Molecular/instrumentação , Desenho de Equipamento , Análise de Falha de Equipamento , Interações Hidrofóbicas e Hidrofílicas , Quartzo/química , Reprodutibilidade dos Testes , Sensibilidade e Especificidade
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