Recent advances in electrocatalytic CO2 reduction with molecular complexes

Fernández, Sergio Gómez; Bandomo, Geyla C. Dubed; Lloret‐Fillol, Julio

doi:10.1016/bs.adioch.2022.01.001

Cited by 5 publications

(3 citation statements)

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“…Incorporating catalytic units into reticular frameworks is an attractive strategy to maximize the number of active sites supported on an electrode and enhance the electrocatalytic activity compared with that of solution-based molecular electrocatalysts and other monolayer immobilization strategies. − In addition, the molecular design of covalent organic frameworks (COFs) allows outstanding control over the chemical environment of the catalytic sites in confined spaces with the aim to stabilize key reaction intermediates and control the activity and selectivity of catalytic processes. Several efforts have been oriented toward the rational design of COFs by varying the size, shape, connectivity, and electronic structures of their molecular building blocks. ,,,− In particular, tuning the electronic structure of the building blocks can strongly influence the COF performance, mimicking the crucial role of ligands in molecular catalysis.…”

Section: Introductionmentioning

confidence: 99%

“…In the field of electrocatalytic reduction of CO 2 to value-added chemicals, extensive work has been focused on catalyst incorporation to tune the catalytic performances of reticular systems. ,− Yaghi and co-workers have demonstrated the ability to tune the CO 2 reduction properties of catalytic sites located at the corners of a COF by modifying the electronic properties of the linkers, indicating that a long-range electronic effect can efficiently promote the tuning of catalytic properties . Bipyridines have also proven to be functional building blocks for COFs in electrocatalysis, similarly to porphyrins. − For example, Marinescu and co-workers evaluated a COF with both metalloporphyrin (Co and Fe) and metal bipyridine (Re) moieties for electrocatalytic CO 2 reduction, highlighting the effect of building blocks on the electrocatalytic properties of COFs and the importance of studying the catalytic activity–structure relationships of these reticular materials …”

Section: Introductionmentioning

confidence: 99%

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Toward the Understanding of the Structure–Activity Correlation in Single-Site Mn Covalent Organic Frameworks for Electrocatalytic CO₂ Reduction

Dubed Bandomo,

Franco,

Liu

et al. 2024

ACS Appl. Energy Mater.

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The encapsulation of organometallic complexes into reticular covalent organic frameworks (COFs) represents an effective strategy for the immobilization of molecular electrocatalysts. In particular, well-defined polypyridyl Mn sites embedded into a crystalline COF backbone (COF bpyMn ) were found to exhibit higher selectivity and activity toward electrochemical CO 2 reduction compared to the parent molecular derivative noncovalently immobilized on carbon electrodes. In situ mechanistic studies revealed that the electronic and steric features of the reticular framework strongly affect the redox mechanism of the Mn sites, stabilizing the formation of a mononuclear Mn(I) radical anion intermediate over the most common off-cycle Mn 0 −Mn 0 dimer. Herein, we report the study of a Mn-based COF (COF PTMn ), introducing a larger phenanthroline building block, to explore how tuning the structural and electronic properties of the lattice may affect the catalytic CO 2 reduction performance and the mechanism at the molecular level of the reticular system. The Mn sites encapsulated into the reticular COF PTMn exhibited a remarkable enhancement in the intrinsic catalytic CO 2 reduction activity at near-neutral pH compared to that of the corresponding noncovalently immobilized molecular derivative. On the other hand, the poor crystallinity and porosity of COF PTMn , likely introduced by the lattice expansion and spatial dynamics of the phenanthroline linker, were found to limit its catalytic performances compared to those of the bipyridyl COF bpyMn analogue. ATR-IR spectroelectrochemistry revealed that the higher spatial mobility of the Mn sites does not completely suppress the Mn 0 −Mn 0 dimerization upon the electrochemical reduction of the Mn sites at the COF bpyMn . This work highlights the positive role of the reticular structure of the material in enhancing its catalytic activity versus that of its molecular counterpart and provides useful hints for the future design and development of efficient reticular frameworks for electrocatalytic applications.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Toward the Understanding of the Structure–Activity Correlation in Single-Site Mn Covalent Organic Frameworks for Electrocatalytic CO₂ Reduction

Dubed Bandomo,

Franco,

Liu

et al. 2024

ACS Appl. Energy Mater.

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“…Several organometallic complexes based on earth-abundant transition metals have been found to selectively convert CO 2 into carbon monoxide (CO), acting as homogeneous electrocatalysts in organic media . Molecular catalysts have also shown promising performances when implemented in aqueous electrolyzers as heterogenized systems on carbon supports . For some catalysts, the predominant formation of formate (HCOO – ) has been reported depending on the ligand structure or the reaction conditions, albeit a selective CO 2 conversion to HCOO – is achieved only in a few cases .…”

Section: Introductionmentioning

confidence: 99%

Decoding the CO₂ Reduction Mechanism of a Highly Active Organometallic Manganese Electrocatalyst: Direct Observation of a Hydride Intermediate and Its Implications

et al. 2023

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A detailed mechanistic study of the electrochemical CO 2 reduction catalyzed by the fac-[Mn I (CO) 3 (bis-Me NHC)MeCN] + complex (1-MeCN + ) is reported herein by combining in situ FTIR spectroelectrochemistry (SEC), synthesis and characterization of catalytic intermediates, and DFT calculations. Under low proton concentrations, 1-MeCN + efficiently catalyzes CO 2 electroreduction with long catalyst durability and selectivity toward CO (ca. 100%). The [Mn -I (CO) 3 (bis-Me NHC)] − anion (1 − ) and the tetracarbonyl [Mn I (CO) 4 (bis-Me NHC)] + complex (1-CO + ) are key intermediates of the catalytic CO 2 -to-CO mechanism due to their impact on the selectivity and the reaction rate, respectively. Increasing the proton concentration increases formate production (up to 15% FE), although CO remains the major product. The origin of formate is ascribed to the competitive protonation of 1 − to form a Mn(I) hydride (1-H), detected by SEC in the absence of CO 2 . 1-H was also synthesized and thoroughly characterized, including by X-ray diffraction analysis. Stoichiometric reactivity studies of 1-H with CO 2 and labeled 13 CO 2 indicate a fast formation of the corresponding neutral Mn(I) formate species (1-OCOH) at room temperature. DFT modeling confirms the intrinsic capability of 1-H to undergo hydride transfer to CO 2 due to the strong σ-donor properties of the bis-Me NHC moiety. However, the large potential required for the HCOO − release from 1-OCOH limits the overall catalytic CO 2 -to-HCOO − cycle. Moreover, the experimentally observed preferential selectivity for CO over formate is dictated by the shallow kinetic barrier for CO 2 binding to 1 − compared to the Mn−H bond formation. The detailed mechanistic study highlights the reduction potential, pK a , and hydricity of the metal hydride intermediate as crucial factors affecting the CO 2 RR selectivity in molecular systems.

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Connecting Biological and Synthetic Approaches for Electrocatalytic CO₂ Reduction

Cobb,

Rodríguez‐Jiménez,

Reisner

2023

Angewandte Chemie

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Electrocatalytic CO2 reduction has developed into a broad field, spanning fundamental studies of enzymatic ‘model’ catalysts to synthetic molecular catalysts and heterogeneous gas diffusion electrodes producing commercially relevant quantities of product. This diversification has resulted in apparent differences and a disconnect between seemingly related approaches when using different types of catalysts. Enzymes possess discrete and well understood active sites that can perform reactions with high selectivity and activities at their thermodynamic limit. Synthetic small molecule catalysts can be designed with desired active site composition but do not yet display enzyme‐like performance. These properties of the biological and small molecule catalysts contrast with heterogeneous materials, which can contain multiple, often poorly understood active sites with distinct reactivity and therefore introducing significant complexity in understanding their activities. As these systems are being better understood and the continuously improving performance of their heterogeneous active sites closes the gap with enzymatic activity, this performance difference between heterogeneous and enzymatic systems begins to close. This convergence removes the barriers between using different types of catalysts and future challenges can be addressed without multiple efforts as a unified picture for the biological‐synthetic catalyst spectrum emerges.

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Recent advances in electrocatalytic CO2 reduction with molecular complexes

Cited by 5 publications

References 205 publications

Toward the Understanding of the Structure–Activity Correlation in Single-Site Mn Covalent Organic Frameworks for Electrocatalytic CO₂ Reduction

Toward the Understanding of the Structure–Activity Correlation in Single-Site Mn Covalent Organic Frameworks for Electrocatalytic CO₂ Reduction

Decoding the CO₂ Reduction Mechanism of a Highly Active Organometallic Manganese Electrocatalyst: Direct Observation of a Hydride Intermediate and Its Implications

Connecting Biological and Synthetic Approaches for Electrocatalytic CO₂ Reduction

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Recent advances in electrocatalytic CO2 reduction with molecular complexes

Cited by 5 publications

References 205 publications

Toward the Understanding of the Structure–Activity Correlation in Single-Site Mn Covalent Organic Frameworks for Electrocatalytic CO2 Reduction

Toward the Understanding of the Structure–Activity Correlation in Single-Site Mn Covalent Organic Frameworks for Electrocatalytic CO2 Reduction

Decoding the CO2 Reduction Mechanism of a Highly Active Organometallic Manganese Electrocatalyst: Direct Observation of a Hydride Intermediate and Its Implications

Connecting Biological and Synthetic Approaches for Electrocatalytic CO2 Reduction

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Toward the Understanding of the Structure–Activity Correlation in Single-Site Mn Covalent Organic Frameworks for Electrocatalytic CO₂ Reduction

Toward the Understanding of the Structure–Activity Correlation in Single-Site Mn Covalent Organic Frameworks for Electrocatalytic CO₂ Reduction

Decoding the CO₂ Reduction Mechanism of a Highly Active Organometallic Manganese Electrocatalyst: Direct Observation of a Hydride Intermediate and Its Implications

Connecting Biological and Synthetic Approaches for Electrocatalytic CO₂ Reduction