Covalent organic frameworks based on electroactive naphthalenediimide as active electrocatalysts toward oxygen reduction reaction

Martínez-Fernández, Marcos; Martínez‐Periñán, Emiliano; Royuela, Sergio; Martínez, José I.; Zamora, Félix; Lorenzo, Encarnación; Segura, José L.

doi:10.1016/j.apmt.2022.101384

Cited by 19 publications

(13 citation statements)

References 92 publications

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“…The highest isosurface map distribution of Azo‐COF will be beneficial to the adsorption of electrophilic oxygen intermediates (Figure 6d, Right) [30] . The density of states (DOS) shows that the Azo‐COF endows the narrowest band gap around the Fermi level, revealing its excellent semiconductor property (Figure 6e) [31] . We then performed ORR free energy of possible active sites of the COFs (Figure 6f).…”

Section: Resultsmentioning

confidence: 99%

“…[30] The density of states (DOS) shows that the Azo-COF endows the narrowest band gap around the level, revealing its excellent semiconductor property (Figure 6e). [31] We then performed ORR free energy of possible active sites of the COFs (Figure 6f). It was found that the overpotentials of para-positioning group C=N (C) of Azo-COF (0.52 eV) and Vinyl-COF (0.53 eV) influenced by the UBs are lower than those of UBs-free Py-COF (0.56 eV).…”

Section: Angewandte Chemiementioning

confidence: 99%

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An Unsaturated Bond Strategy to Regulate Active Centers of Metal‐Free Covalent Organic Frameworks for Efficient Oxygen Reduction

et al. 2022

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Unsaturated environment is the key to affect catalytic activity of the oxygen reduction reaction (ORR). Unveiling the effect of unsaturated sites toward ORR activity is of importance due to the vague unsaturated states. Reported here is a proof‐of‐concept strategy on the evaluation of unsaturated bonds (UBs) on adjacent carbon environment by precisely developing two metal‐free vinyl‐/azo‐decorated covalent organic frameworks (Vinyl‐COF and Azo‐COF) as catalysts. The as‐prepared UB‐COFs exhibit good performance than the control Py‐COF and comparable to the most reported carbon catalysts. Supported by theory calculations and in situ Raman spectra‐electrochemistry, it is revealed that the UBs in organic catalysts can produce para‐activation, identifying the para C=N groups as active centers. Importantly, the intrinsic UBs can induce local charge redistribution, and make the molecular skeleton possess high isosurface map distribution, with an efficient affinity for oxygen intermediates.

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Section: Resultsmentioning

confidence: 99%

Section: Angewandte Chemiementioning

confidence: 99%

An Unsaturated Bond Strategy to Regulate Active Centers of Metal‐Free Covalent Organic Frameworks for Efficient Oxygen Reduction

et al. 2022

View full text Add to dashboard Cite

show abstract

“…[30] The density of states (DOS) shows that the Azo-COF endows the narrowest band gap around the Fermi level, revealing its excellent semiconductor property (Figure 6e). [31] We then performed ORR free energy of possible active sites of the COFs (Figure 6f). It was found that the overpotentials of para-positioning group C=N (C) of Azo-COF (0.52 eV) and Vinyl-COF (0.53 eV) influenced by the UBs are lower than those of UBs-free Py-COF (0.56 eV).…”

Section: Methodsmentioning

confidence: 99%

An Unsaturated Bond Strategy to Regulate Active Centers of Metal‐Free Covalent Organic Frameworks for Efficient Oxygen Reduction

et al. 2022

View full text Add to dashboard Cite

Unsaturated environment is the key to affect catalytic activity of the oxygen reduction reaction (ORR). Unveiling the effect of unsaturated sites toward ORR activity is of importance due to the vague unsaturated states. Reported here is a proof-of-concept strategy on the evaluation of unsaturated bonds (UBs) on adjacent carbon environment by precisely developing two metal-free vinyl-/azo-decorated covalent organic frameworks (Vinyl-COF and Azo-COF) as catalysts. The as-prepared UB-COFs exhibit good performance than the control Py-COF and comparable to the most reported carbon catalysts. Supported by theory calculations and in situ Raman spectra-electrochemistry, it is revealed that the UBs in organic catalysts can produce para-activation, identifying the para C=N groups as active centers. Importantly, the intrinsic UBs can induce local charge redistribution, and make the molecular skeleton possess high isosurface map distribution, with an efficient affinity for oxygen intermediates.

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“…DAF-COF with an MG-bound biphenyl structure (and therefore larger electron delocalization for superior conductivity) exhibits better catalytic activity than the twisted MGconstructed MBD-COF, which is among the highest activities of the currently reported metal-free COF-based electrocatalysts. [10][11][12][13][14][15][16][17][18][19][20] The uniform morphology with a good surface area and typical donor-acceptor (D-A) properties enables effective charge transfer, promoting the ORR process. This strategy to decorate MGs into COFs in a controllable manner, and understand the valence bond regulation mechanism provides an efficient and facile way for the site-specific design of novel electrochemical electrode materials.…”

Section: Introductionmentioning

confidence: 99%

Metal‐Free Carbon‐Based Covalent Organic Frameworks with Heteroatom‐Free Units Boost Efficient Oxygen Reduction

et al. 2022

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Accurate identification of carbon‐based metal‐free electrocatalyst (CMFE) activity and enhancing their catalytic efficiency for O2 conversion is an urgent and challenging task. This study reports a promising strategy to simultaneously develop a series of covalent organic frameworks (COFs) with well‐defined heterocyclic‐free biphenyl or fluorenyl units. Unlike heteroatom doping, the developed method not only supplies methyl‐induced molecular configuration to promote activity, but also provides a direct opportunity to identify heteroatom‐free carbon active centers. The introduction of methyl groups (MGs) with reversible valence bonds into a pristine biphenyl‐based COF results in an excellent performance with a half‐wave potential of 0.74 V versus the reversible hydrogen electrode (RHE), which is among the highest values for CMFE‐COFs as oxygen reduction reaction (ORR) electrocatalysts. Combined with in situ Raman spectra and theoretical calculations, the MG‐bound skeleton (DAF‐COF) is found to produce ortho activation, confirming the ortho carbon (site‐5) adjacent to MGs as active centers. This may be attributed to the opening and binding of MGs, which effectively regulate the molecular configuration and charge redistribution, as well as improve charge transfer and reduce the energy barrier. This study provides insight into the design of highly efficient metal‐free organic electrocatalysts via the regulation of valence bonds.

show abstract

Covalent organic frameworks based on electroactive naphthalenediimide as active electrocatalysts toward oxygen reduction reaction

Cited by 19 publications

References 92 publications

An Unsaturated Bond Strategy to Regulate Active Centers of Metal‐Free Covalent Organic Frameworks for Efficient Oxygen Reduction

An Unsaturated Bond Strategy to Regulate Active Centers of Metal‐Free Covalent Organic Frameworks for Efficient Oxygen Reduction

An Unsaturated Bond Strategy to Regulate Active Centers of Metal‐Free Covalent Organic Frameworks for Efficient Oxygen Reduction

Metal‐Free Carbon‐Based Covalent Organic Frameworks with Heteroatom‐Free Units Boost Efficient Oxygen Reduction

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