Porous, Crystalline, Covalent Organic Frameworks
18 Nov 2005-Science (American Association for the Advancement of Science)-Vol. 310, Iss: 5751, pp 1166-1170
TL;DR: Covalent organic frameworks (COFs) have been designed and successfully synthesized by condensation reactions of phenyl diboronic acid and hexahydroxytriphenylene to form rigid porous architectures with pore sizes ranging from 7 to 27 angstroms.
Abstract: Covalent organic frameworks (COFs) have been designed and successfully synthesized by condensation reactions of phenyl diboronic acid {C6H4[B(OH)2]2} and hexahydroxytriphenylene [C18H6(OH)6]. Powder x-ray diffraction studies of the highly crystalline products (C3H2BO)6.(C9H12)1 (COF-1) and C9H4BO2 (COF-5) revealed expanded porous graphitic layers that are either staggered (COF-1, P6(3)/mmc) or eclipsed (COF-5, P6/mmm). Their crystal structures are entirely held by strong bonds between B, C, and O atoms to form rigid porous architectures with pore sizes ranging from 7 to 27 angstroms. COF-1 and COF-5 exhibit high thermal stability (to temperatures up to 500 degrees to 600 degrees C), permanent porosity, and high surface areas (711 and 1590 square meters per gram, respectively).
Citations
More filters
TL;DR: A comprehensive review of the COF field is targeted, providing a historic overview of the chemistry, the advances in the topology design and synthetic reactions, illustrate the structural features and diversities, and scrutinize the development and potential of various functions through elucidating structure-function correlations.
Abstract: Covalent organic frameworks (COFs) are a class of crystalline porous organic polymers with permanent porosity and highly ordered structures. Unlike other polymers, a significant feature of COFs is that they are structurally predesignable, synthetically controllable, and functionally manageable. In principle, the topological design diagram offers geometric guidance for the structural tiling of extended porous polygons, and the polycondensation reactions provide synthetic ways to construct the predesigned primary and high-order structures. Progress over the past decade in the chemistry of these two aspects undoubtedly established the base of the COF field. By virtue of the availability of organic units and the diversity of topologies and linkages, COFs have emerged as a new field of organic materials that offer a powerful molecular platform for complex structural design and tailor-made functional development. Here we target a comprehensive review of the COF field, provide a historic overview of the chemistry of the COF field, survey the advances in the topology design and synthetic reactions, illustrate the structural features and diversities, scrutinize the development and potential of various functions through elucidating structure-function correlations based on interactions with photons, electrons, holes, spins, ions, and molecules, discuss the key fundamental and challenging issues that need to be addressed, and predict the future directions from chemistry, physics, and materials perspectives.
1,447 citations
TL;DR: The state-of-the-art progress toward mechanisms, new materials, and novel device designs for supercapacitors is summarized and key technical challenges are highlighted regarding further research in this thriving field.
Abstract: Notably, many significant breakthroughs for a new generation of supercapacitors have been reported in recent years, related to theoretical understanding, material synthesis and device designs. Herein, we summarize the state-of-the-art progress toward mechanisms, new materials, and novel device designs for supercapacitors. Firstly, fundamental understanding of the mechanism is mainly focused on the relationship between the structural properties of electrode materials and their electrochemical performances based on some in situ characterization techniques and simulations. Secondly, some emerging electrode materials are discussed, including metal–organic frameworks (MOFs), covalent organic frameworks (COFs), MXenes, metal nitrides, black phosphorus, LaMnO3, and RbAg4I5/graphite. Thirdly, the device innovations for the next generation of supercapacitors are provided successively, mainly emphasizing flow supercapacitors, alternating current (AC) line-filtering supercapacitors, redox electrolyte enhanced supercapacitors, metal ion hybrid supercapacitors, micro-supercapacitors (fiber, plane and three-dimensional) and multifunctional supercapacitors including electrochromic supercapacitors, self-healing supercapacitors, piezoelectric supercapacitors, shape-memory supercapacitors, thermal self-protective supercapacitors, thermal self-charging supercapacitors, and photo self-charging supercapacitors. Finally, the future developments and key technical challenges are highlighted regarding further research in this thriving field.
1,397 citations
TL;DR: The fundamental relationships between electronic structure, adsorption energy, and apparent activity for a wide variety of 2D electrocatalysts are described with the goal of providing a better understanding of these emerging nanomaterials at the atomic level.
Abstract: Over the past few decades, the design and development of advanced electrocatalysts for efficient energy conversion technologies have been subjects of extensive study. With the discovery of graphene, two-dimensional (2D) nanomaterials have emerged as some of the most promising candidates for heterogeneous electrocatalysts due to their unique physical, chemical, and electronic properties. Here, we review 2D-nanomaterial-based electrocatalysts for selected electrocatalytic processes. We first discuss the unique advances in 2D electrocatalysts based on different compositions and functions followed by specific design principles. Following this overview, we discuss various 2D electrocatalysts for electrocatalytic processes involved in the water cycle, carbon cycle, and nitrogen cycle from their fundamental conception to their functional application. We place a significant emphasis on different engineering strategies for 2D nanomaterials and the influence these strategies have on intrinsic material performance, ...
1,363 citations
TL;DR: CMPs are unique in that they allow the complementary utilization of π-conjugated skeletons and nanopores for functional exploration and have shown great potential for challenging energy and environmental issues, as exemplified by their excellent performance in gas adsorption, heterogeneous catalysis, light emitting, light harvesting and electrical energy storage.
Abstract: Conjugated microporous polymers (CMPs) are a class of organic porous polymers that combine π-conjugated skeletons with permanent nanopores, in sharp contrast to other porous materials that are not π-conjugated and with conventional conjugated polymers that are nonporous. As an emerging material platform, CMPs offer a high flexibility for the molecular design of conjugated skeletons and nanopores. Various chemical reactions, building blocks and synthetic methods have been developed and a broad variety of CMPs with different structures and specific properties have been synthesized, driving the rapid growth of the field. CMPs are unique in that they allow the complementary utilization of π-conjugated skeletons and nanopores for functional exploration; they have shown great potential for challenging energy and environmental issues, as exemplified by their excellent performance in gas adsorption, heterogeneous catalysis, light emitting, light harvesting and electrical energy storage. This review describes the molecular design principles of CMPs, advancements in synthetic and structural studies and the frontiers of functional exploration and potential applications.
1,335 citations
TL;DR: In this paper, the authors classified solid CO2-adsorbents into three types according to their sorption/desorption temperatures: low-, intermediate-and high-temperature adsorbents with temperatures ranging from below 200 °C, between 200-400 °C and above 400 °C.
Abstract: In the last few years there has been a rapid growth in governmental funding and research activities worldwide for CO2 capture, storage and utilization (CSU), due to increasing awareness of the link between CO2 accumulation in the atmosphere and global warming. Among the various technologies and processes that have been developed and are emerging for CSU of CO2, solid CO2-adsorbents are widely applied. In this review, these solid CO2-adsorbents are classified into three types according to their sorption/desorption temperatures: low-, intermediate- and high-temperature adsorbents with temperatures ranging from below 200 °C, between 200–400 °C and above 400 °C, respectively. For each type of solid CO2-adsorbent, the synthesis, interaction mechanism with CO2 and sorption performance, potential applications and problems are reviewed. In the last section, several representative CO2-sorption-enhanced catalytic reactions are discussed. It is expected that this review will not only summarize the main research activities in this area, but also find possible links between fundamental studies and industrial applications.
1,326 citations
References
More filters
Book•
05 Oct 1998
TL;DR: In this paper, the authors provide an introductory review of the various theoretical and practical aspects of adsorption by powders and porous solids with particular reference to materials of technological importance.
Abstract: The declared objective of this book is to provide an introductory review of the various theoretical and practical aspects of adsorption by powders and porous solids with particular reference to materials of technological importance. The primary aim is to meet the needs of students and non-specialists, who are new to surface science or who wish to use the advanced techniques now available for the determination of surface area, pore size and surface characterization. In addition, a critical account is given of recent work on the adsorptive properties of activated carbons, oxides, clays and zeolites. Key Features * Provides a comprehensive treatment of adsorption at both the gas/solid interface and the liquid/solid interface * Includes chapters dealing with experimental methodology and the interpretation of adsorption data obtained with porous oxides, carbons and zeolites * Techniques capture the importance of heterogeneous catalysis, chemical engineering and the production of pigments, cements, agrochemicals, and pharmaceuticals
3,128 citations
"Porous, Crystalline, Covalent Organ..." refers background in this paper
...At higher pressures, a slow rise in the isotherm occurs because of the existence of a small population of external mesopores between the crystallites; this feature is not uncommon for particles with platelet morphologies (19)....
[...]
...These values surpass those of other layered materials, including graphite (10 m(2) g), clays (10 to 100 m(2) g), and pillared clays (50 to 300 m(2) g) and are in the range of the most porous zeolites and many porous carbons (19)....
[...]
...The total surface area was calculated to be 711 m(2) g, with a micropore contribution of 587 m(2) g (83%) and mesopore contribution of 124 m(2) g (17%) from de Boer statistical thickness (t-plot) analysis (19)....
[...]
TL;DR: The surfactant-mediated synthesis of an ordered benzene–silica hybrid material has an hexagonal array of mesopores and crystal-like pore walls that exhibit structural periodicity, and it is expected that other organosilicas and organo-metal oxides can be produced in a similar fashion, to yield a range of hierarchically ordered mesoporous solids with molecular-scale pore surface periodicity.
Abstract: Surfactant-mediated synthesis strategies are widely used to fabricate ordered mesoporous solids in the form of metal oxides, metals, carbon and hybrid organosilicas. These materials have amorphous pore walls, which could limit their practical utility. In the case of mesoporous metal oxides, efforts to crystallize the framework structure by thermal and hydrothermal treatments have resulted in crystallization of only a fraction of the pore walls. Here we report the surfactant-mediated synthesis of an ordered benzene-silica hybrid material; this material has an hexagonal array of mesopores with a lattice constant of 52.5 A, and crystal-like pore walls that exhibit structural periodicity with a spacing of 7.6 A along the channel direction. The periodic pore surface structure results from alternating hydrophilic and hydrophobic layers, composed of silica and benzene, respectively. We believe that this material is formed as a result of structure-directing interactions between the benzene-silica precursor molecules, and between the precursor molecules and the surfactants. We expect that other organosilicas and organo-metal oxides can be produced in a similar fashion, to yield a range of hierarchically ordered mesoporous solids with molecular-scale pore surface periodicity.
1,216 citations
TL;DR: In this paper, a unified approach to pore size characterization of microporous carbonaceous materials such as activated carbon and carbon fibers by nitrogen, argon, and carbon dioxide adsorption at standard temperatures, 77 K for N2 and Ar and 273 K for CO2, was presented.
Abstract: We present a unified approach to pore size characterization of microporous carbonaceous materials such as activated carbon and carbon fibers by nitrogen, argon, and carbon dioxide adsorption at standard temperatures, 77 K for N2 and Ar and 273 K for CO2. Reference isotherms of N2, Ar, and CO2 in a series of model slit-shaped carbon pores in the range from 0.3 to 36 nm have been calculated from the nonlocal density functional theory (NLDFT) using validated parameters of intermolecular interactions. Carbon dioxide isotherms have also been generated by the grand canonical Monte Carlo (GCMC) method based on the 3-center model of Harris and Yung. The validation of model parameters includes three steps: (1) prediction of vapor−liquid equilibrium data in the bulk system, (2) prediction of adsorption isotherm on graphite surface, (3) comparison of the NLDFT adsorption isotherms in pores to those of GCMC simulations, performed with the parameters of fluid-fluid interactions, which accurately reproduce vapor−liqui...
657 citations
TL;DR: In this paper, the pore size of MCM-41 materials was estimated based on geometrical considerations of the ratio of pore volume to pore wall volume for an infinite hexagonal array of cylindrical pores.
Abstract: Nitrogen adsorption measurements were performed over a wide range of relative pressures (10-6−0.995) for a series of siliceous MCM-41 samples obtained using alkyltrimethylammonium surfactants with different chain length. Both high- and low-pressure adsorption data were analyzed. The pore size was shown to increase in a regular way with the chain length of the surfactant used. Moreover, a very good correlation between the pore size and the interplanar spacing of the MCM-41 samples was observed. Methods used to calculate the pore diameter were critically compared, and a new procedure to estimate the pore size of MCM-41 materials was proposed. This new procedure is based on geometrical considerations of the ratio of the pore volume to the pore wall volume for an infinite hexagonal array of cylindrical pores. Adsorption measurements showed that the amount adsorbed in the low-pressure region increases with a decrease in the pore size of the samples probably because of the enhancement of the gas−surface interac...
465 citations