Nano-sized metal-organic frameworks: Synthesis and applications

Cai, Xuechao; Xie, Zhongxi; Li, Dandan; Kassymova, Meruyert; Zang, Shuang‐Quan; Jiang, Hai‐Long

doi:10.1016/j.ccr.2020.213366

“…Co porphyrins are active and robust for electrocatalytic ORR, which is a significant process in many new energy conversion technologies, including fuel cells and metal–air batteries [34–41] . Through ligand exchange, [42–45] we can graft Co porphyrins on MOF surfaces (Figure 1 c), considering the following benefits of using MOFs as supports [46–53] . First, with different metals and organic linkers, the compositions of MOFs can be modified to make diverse hybrids.…”

Section: Figurementioning

confidence: 99%

Metal–Organic‐Framework‐Supported Molecular Electrocatalysis for the Oxygen Reduction Reaction

Liang

¹

,

Guo

²

,

Zhou

³

et al. 2021

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Synthesizing molecule@support hybrids is appealing to improve molecular electrocatalysis. We report herein metal–organic framework (MOF)‐supported Co porphyrins for the oxygen reduction reaction (ORR) with improved activity and selectivity. Co porphyrins can be grafted on MOF surfaces through ligand exchange. A variety of porphyrin@MOF hybrids were made using this method. Grafted Co porphyrins showed boosted ORR activity with large (>70 mV) anodic shift of the half‐wave potential compared to ungrafted porphyrins. By using active MOFs for peroxide reduction, the number of electrons transferred per O2 increased from 2.65 to 3.70, showing significantly improved selectivity for the 4e ORR. It is demonstrated that H2O2 generated from O2 reduction at Co porphyrins is further reduced at MOF surfaces, leading to improved 4e ORR. As a practical demonstration, these hybrids were used as air electrode catalysts in Zn‐air batteries, which exhibited equal performance to that with Pt‐based materials.

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“…[1][2][3][4][5][6][7][8][9][10] In virtue of many well-developed construction strategies, hundreds of thousands of MOFs are obtained through direct or post-synthetic approaches, contributing enormous structural and functional diversity. [11][12][13][14] Despite a few robust MOFs, such as the famous UiO, [15,16] ZIF, [17,18] MOF, [19][20][21][22] MIL, [23,24] PCN, [25][26][27] and NU series, [28,29] most of existing MOFs are far away from practical use due to their relatively weak stability. Therefore, developing methods to stabilize labile MOFs would help remove the limitation on their application scope imposed by the framework fragility, and thus unlock more possibilities for the MOF community.…”

Section: Introductionmentioning

confidence: 99%

In Situ Porphyrin Substitution in a Zr(IV)‐MOF for Stability Enhancement and Photocatalytic CO₂ Reduction

Kong

¹

,

He

²

,

Zhou

³

et al. 2021

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Despite numerous inherent merits of metal-organic frameworks (MOFs), structural fragility has imposed great restrictions on their wider involvement in many applications, such as in catalysis. Herein, a strategy for enhancing stability and enabling functionality in a labile Zr(IV)-MOF has been proposed by in situ porphyrin substitution. A size-and geometry-matched robust linear porphyrin ligand 4,4′-(porphyrin-5,15-diyl)dibenzolate (DCPP 2− ) is selected to replace the 4,4′-(1,3,6,8-tetraoxobenzo[lmn][3,8]phenanthroline-2,7(1H,3H,6H,8H)-diyl)dibenzoate (NDIDB 2− ) ligand in the synthesis of BUT-109(Zr), affording BUT-110 with varied porphyrin contents. Compared to BUT-109(Zr), the chemical stability of BUT-110 series is greatly improved. Metalloporphyrin incorporation endows BUT-110 MOFs with high catalytic activity in the photoreduction of CO 2 , in the absence of photosensitizers. By tuning the metal species and porphyrin contents in BUT-110, the resulting BUT-110-50%-Co is demonstrated to be a good photocatalyst for selective CO 2 -to-CO reduction, via balancing the chemical stability, photocatalytic efficiency, and synthetic cost. This work highlights the advantages of in situ ligand substitution for MOF modification, by which uniform distribution and high content of the incoming ligand are accessible in the resulting MOFs.More importantly, it provides a promising approach to convert unstable MOFs, which mainly constitute the vast MOF database but have always been neglected, into robust functional materials.

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“…[34][35][36][37][38][39][40][41] Through ligand exchange, [42][43][44][45] we can graft Co porphyrins on MOF surfaces (Figure 1 c), considering the following benefits of using MOFs as supports. [46][47][48][49][50][51][52][53] First, with different metals and organic linkers, the compositions of MOFs can be modified to make diverse hybrids. Second, the shape and size of MOFs can be tuned to optimize electron transfer and mass transportation for electrocatalysis.…”

mentioning

confidence: 99%

Metal–Organic‐Framework‐Supported Molecular Electrocatalysis for the Oxygen Reduction Reaction

Liang

¹

,

Guo

²

,

Zhou

³

et al. 2021

View full text Add to dashboard Cite

Synthesizing molecule@support hybrids is appealing to improve molecular electrocatalysis. We report herein metal–organic framework (MOF)‐supported Co porphyrins for the oxygen reduction reaction (ORR) with improved activity and selectivity. Co porphyrins can be grafted on MOF surfaces through ligand exchange. A variety of porphyrin@MOF hybrids were made using this method. Grafted Co porphyrins showed boosted ORR activity with large (>70 mV) anodic shift of the half‐wave potential compared to ungrafted porphyrins. By using active MOFs for peroxide reduction, the number of electrons transferred per O2 increased from 2.65 to 3.70, showing significantly improved selectivity for the 4e ORR. It is demonstrated that H2O2 generated from O2 reduction at Co porphyrins is further reduced at MOF surfaces, leading to improved 4e ORR. As a practical demonstration, these hybrids were used as air electrode catalysts in Zn‐air batteries, which exhibited equal performance to that with Pt‐based materials.

show abstract

Nano-sized metal-organic frameworks: Synthesis and applications

Cited by 214 publications

References 200 publications

Metal–Organic‐Framework‐Supported Molecular Electrocatalysis for the Oxygen Reduction Reaction

Metal–Organic‐Framework‐Supported Molecular Electrocatalysis for the Oxygen Reduction Reaction

In Situ Porphyrin Substitution in a Zr(IV)‐MOF for Stability Enhancement and Photocatalytic CO₂ Reduction

Metal–Organic‐Framework‐Supported Molecular Electrocatalysis for the Oxygen Reduction Reaction

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Nano-sized metal-organic frameworks: Synthesis and applications

Cited by 214 publications

References 200 publications

Metal–Organic‐Framework‐Supported Molecular Electrocatalysis for the Oxygen Reduction Reaction

Metal–Organic‐Framework‐Supported Molecular Electrocatalysis for the Oxygen Reduction Reaction

In Situ Porphyrin Substitution in a Zr(IV)‐MOF for Stability Enhancement and Photocatalytic CO2 Reduction

Metal–Organic‐Framework‐Supported Molecular Electrocatalysis for the Oxygen Reduction Reaction

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Product

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In Situ Porphyrin Substitution in a Zr(IV)‐MOF for Stability Enhancement and Photocatalytic CO₂ Reduction