A Pyrolysis‐Free Covalent Organic Polymer for Oxygen Reduction

Guo, Jianing; Lin, Chih Kuang; Xia, Zhaoqiang; Xiang, Zhonghua

doi:10.1002/ange.201808226

Cited by 29 publications

(11 citation statements)

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“…Carbon-based catalysts with nitrogen-coordinated single transition metal atoms as active sites have emerged as promising systems for catalytic processes because of their maximal atom utilization and highly catalytic activity (1)(2)(3)(4)(5)(6)(7)(8). As revealed both experimentally and theoretically, the nitrogen-coordinated single transition metal moieties supported in carbon provide versatile active sites, while the carbon matrix ensures a large specific area and efficient mass transport, provides a stable matrix for the metal atoms, and affects the electronic density owing to strong intermolecular interactions (9)(10)(11)(12)(13)(14)(15)(16). Currently, reported strategies to prepare the N-coordinated single-atom catalysts (SACs) dominantly depend on high-temperature pyrolysis, which highly demands the rigorous manipulation of the carbonization process and precise elemental ratio of precursors (17)(18)(19)(20)(21).…”

Section: Introductionmentioning

confidence: 99%

A pyrolysis-free path toward superiorly catalytic nitrogen-coordinated single atom

et al. 2019

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Nitrogen-coordinated single-atom catalysts (SACs) have emerged as a frontier for electrocatalysis (such as oxygen reduction) with maximized atom utilization and highly catalytic activity. The precise design and operable synthesis of SACs are vital for practical applications but remain challenging because the commonly used high-temperature treatments always result in unpredictable structural changes and randomly created single atoms. Here, we develop a pyrolysis-free synthetic approach to prepare SACs with a high electrocatalytic activity using a fully π-conjugated iron phthalocyanine (FePc)–rich covalent organic framework (COF). Instead of randomly creating Fe-nitrogen moieties on a carbon matrix (Fe-N-C) through pyrolysis, we rivet the atomically well-designed Fe-N-C centers via intermolecular interactions between the COF network and the graphene matrix. The as-synthesized catalysts demonstrate exceptional kinetic current density in oxygen reduction catalysis (four times higher than the benchmark Pt/C) and superior power density and cycling stability in Zn-air batteries compared with Pt/C as air electrodes.

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Section: Introductionmentioning

confidence: 99%

A pyrolysis-free path toward superiorly catalytic nitrogen-coordinated single atom

et al. 2019

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“…Recently, organic materials have attracted attention as promising electrocatalysts because of their multielement composition, high atomic precision, and structural tunability. − Among them, the crystalline porous covalent organic frameworks (COFs) have been synthesized during the last 10 years. − The structural tunability and regularity and desired porosity of COFs with advisible building blocks enable them to present potential applications in renewable energy fields − such as photocatalysis, electrocatalysis, and energy storage. Exploiting metal-free COF electrocatalysts with responsive ORR-active heterocyclic structures could precisely confirm the active centers and intrinsic ORR catalytic mechanism derived from defects and heteroatoms.…”

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confidence: 99%

Metal-Free Thiophene-Sulfur Covalent Organic Frameworks: Precise and Controllable Synthesis of Catalytic Active Sites for Oxygen Reduction

et al. 2020

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Defective or heteroatom-doped metal-free carbon materials (MFCMs) have been regarded as efficient oxygen reduction reaction (ORR) catalysts in the past decade. However, the active centers for ORR in MFCMs are hard to confirm precisely and synthesize controllably through common methods such as high-temperature pyrolysis or heteroatom doping. To verify the precise structure acting as the active center for the ORR, we first report two crystalline metal-free thiophene-sulfur covalent organic frameworks (MFTS-COFs) as ORR catalysts. The MFTS-COFs show more positive catalytic capability than the thiophenefree COF, indicating that pentacyclic thiophene-sulfur building blocks act as active centers to induce ORR catalytic activity. MFTS-COFs with higher contents of thiophene-sulfur exhibit better ORR performance. The experimental identification is supported by density functional theory calculations. These results thus demonstrate that rational design and precise synthesis of metal-free crystalline organic materials can promote the development of new ORR catalysts.

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“…3a and b). [48][49][50][51] The XPS after the deconvolution shows the pristine CNF and DqDaTp display the C1s peak at 284.5 and 284.8 eV respectively (Supporting Information, Figure S26). However, the XPS profile of the DqDaTp-CNF hybrid shows a C1s peak at 285.9 eV.…”

Section: Resultsmentioning

confidence: 99%

Weak Intermolecular Interactions in Covalent Organic Framework-Carbon Nanofiber Based Crystalline yet Flexible Devices

Mohammed

Vijayakumar

Halder

et al. 2019

ACS Appl. Mater. Interfaces

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The redox-active and porous structural backbone of covalent organic frameworks (COFs) can facilitate high-performance electrochemical energy storage devices. However, the utilities of such 2D-materials as supercapacitor electrodes in advanced self power-pack systems have been obstructed due to the poor electrical conductivity and subsequent indigent performance. Herein, we report an effective strategy to enhance the electrical conductivity of COF thin sheets through the in situ solid-state inclusion of carbon nanofiber (CNF) into the COF precursor matrix. The obtained COF-CNF hybrids possess a significant intermolecular ••• interaction between COF and the graphene layers of the CNF. As a result, these COF-CNF hybrids (DqTp-CNF and DqDaTp-CNF) exhibit good electrical conductivity (0.25×10 -3 Scm -1 ), as well as high performance in electrochemical energy storage (DqTp-CNF: 464 mFcm -2 at 0.25 mAcm -2 ). Also, the fabricated, mechanically strong quasi-solid-state supercapacitor (DqDaTp-CNF SC) delivered an ultra-high device capacitance of 167 mFcm -2 at 0.5 mAcm -2 . Furthermore, we integrated a monolithic photovoltaic self-charging power-pack by assembling DqDaTp-CNF SC with a perovskite solar cell. The fabricated self power-pack delivered excellent performance in the areal capacitance (42 mFcm -2 ) at 0.25 mAcm -2 after photo charging for 300 seconds.

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A Pyrolysis‐Free Covalent Organic Polymer for Oxygen Reduction

Cited by 29 publications

References 50 publications

A pyrolysis-free path toward superiorly catalytic nitrogen-coordinated single atom

A pyrolysis-free path toward superiorly catalytic nitrogen-coordinated single atom

Metal-Free Thiophene-Sulfur Covalent Organic Frameworks: Precise and Controllable Synthesis of Catalytic Active Sites for Oxygen Reduction

Weak Intermolecular Interactions in Covalent Organic Framework-Carbon Nanofiber Based Crystalline yet Flexible Devices

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