Homogeneous and heterogeneous molecular catalysts for electrochemical reduction of carbon dioxide

Abdinejad, Maryam; Hossain, M. Nur; Kraatz, Heinz‐Bernhard

doi:10.1039/d0ra07973a

Cited by 26 publications

(21 citation statements)

References 164 publications

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“…Because of the intimate contact and interaction between the catalyst molecules and that between the catalyst molecule and electrode, the inhomogeneity at the reaction interface allows many factors to affect the catalytic reactivity of heterogenized molecules. This intrinsic complexity opens up opportunities for using interdisciplinary approaches to bridge the gap between homogeneous and heterogeneous catalysis, as has been demonstrated in recent studies of immobilized molecules achieving superior catalytic performance. − …”

Section: Introductionmentioning

confidence: 99%

Heterogeneous Molecular Catalysts of Metal Phthalocyanines for Electrochemical CO₂ Reduction Reactions

2021

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Metrics & MoreArticle Recommendations CONSPECTUS: Molecular catalysts, often deployed in homogeneous conditions, are favorable systems for structure−reactivity correlation studies of electrochemical reactions because of their well-defined active site structures and ease of mechanistic investigation. In pursuit of selective and active electrocatalysts for the CO 2 reduction reactions which are promising for converting carbon emissions to useful fuels and chemical products, it is desirable to support molecular catalysts on substrates because heterogeneous catalysts can afford the high current density and operational convenience that practical electrolyzers require. Herein, we share our understanding in the development of heterogenized metal phthalocyanine catalysts for the electrochemical reduction of CO 2 . From the optimization of preparation methods and material structures for the electrocatalytic activity toward CO 2 reduction to CO, we find that molecular-level dispersion of the active material and high electrical conductivity of the support are among the most important factors controlling the activity. The molecular nature of the active site enables mechanism-based optimization. We demonstrate how electron-withdrawing and -donating ligand substituents can be utilized to modify the redox property of the molecule and improve its catalytic activity and stability. Adjusting these factors further allows us to achieve electrochemical reduction of CO 2 to methanol with appreciable activity, which has not been attainable by conventional molecular catalysts. The six-electron reduction process goes through CO as the key intermediate. Rapid and continuous electron delivery to the active site favors further reduction of CO to methanol. We also point out that, in homogeneous electrocatalysis where the catalyst molecules are dissolved in the electrolyte solution, even if the molecular structure remains intact, the actual catalysis may be dominated by molecules permanently adsorbed on the electrode surface and is thus heterogeneous in nature. This account uses our research on CO 2 electroreduction reactions catalyzed by metal phthalocyanine molecules to illustrate our understanding about heterogeneous molecular electrocatalysis, which is also applicable to other electrochemical systems.

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Section: Introductionmentioning

confidence: 99%

Heterogeneous Molecular Catalysts of Metal Phthalocyanines for Electrochemical CO₂ Reduction Reactions

2021

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“…3 To subvert activity and selectivity challenges for CO2 reduction, researchers have developed numerous classes of catalysts. Two classes frequently used and modified are: bulk transition metals, 4 and molecular catalysts 5,6 . Both seek to activate the linear CO2 molecule towards a desired product at enhanced reaction rates, while simultaneously limiting the electrochemical activity of the competing HER.…”

Section: Introductionmentioning

confidence: 99%

CO₂ Electrolysis via Surface-Engineering Electrografted Pyridines on Silver Catalysts

et al. 2022

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The electrochemical reduction of carbon dioxide (CO2) to value-added materials has received considerable attention. Both bulk transition metal catalysts, and molecular catalysts affixed to conductive non-catalytic solid supports, represents a promising approach towards electroreduction of CO2. Here, we report a combined silver (Ag) and pyridine catalyst through a green and irreversible electrografting process, which demonstrates enhanced CO2 conversion versus the individual counterparts. We find by tailoring the pyridine carbon chain length, a 200 mV shift in the onset potential is obtainable compared to the bare silver electrode. A 10-fold activity enhancement at -0.7 V vs RHE is then observed with demonstratable higher partial current densities for CO indicating a co-catalytic effect is attainable through the integration of the two different catalytic structures. We extended performance to a flow cell operating at 150 mA/cm 2 , demonstrating the approach's potential for substantial adaption with various transition metals as supports, and electrografted molecular co-catalysts.

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“…1 Electrocatalytic carbon dioxide reduction reactions (CO 2 RRs) to value added materials such as formic acid (HCOOH), carbon monoxide (CO), methane (CH 4 ), methanol (CH 3 OH), and ethanol (C 2 H 5 OH), have drawn significant attention to mitigate climate change. [2][3][4][5][6][7][8] Formate, in particular, is valued as an ideal candidate for hydrogen storage and fuel cell processes. 9,10 However, due to the complexity of its multi-electron reaction pathway and competition with hydrogen evolution reactions (HERs), the reaction is sluggish and hindered by a large activation overpotential.…”

Section: Introductionmentioning

confidence: 99%

Electroreduction of carbon dioxide to formate using highly efficient bimetallic Sn–Pd aerogels

et al. 2022

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Homogeneous and heterogeneous molecular catalysts for electrochemical reduction of carbon dioxide

Abstract: Electroreduction of CO2 to CO using molecular catalysis.

Cited by 26 publications

References 164 publications

Heterogeneous Molecular Catalysts of Metal Phthalocyanines for Electrochemical CO₂ Reduction Reactions

Heterogeneous Molecular Catalysts of Metal Phthalocyanines for Electrochemical CO₂ Reduction Reactions

CO₂ Electrolysis via Surface-Engineering Electrografted Pyridines on Silver Catalysts

Electroreduction of carbon dioxide to formate using highly efficient bimetallic Sn–Pd aerogels

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Homogeneous and heterogeneous molecular catalysts for electrochemical reduction of carbon dioxide

Abstract: Electroreduction of CO2 to CO using molecular catalysis.

Cited by 26 publications

References 164 publications

Heterogeneous Molecular Catalysts of Metal Phthalocyanines for Electrochemical CO2 Reduction Reactions

Heterogeneous Molecular Catalysts of Metal Phthalocyanines for Electrochemical CO2 Reduction Reactions

CO2 Electrolysis via Surface-Engineering Electrografted Pyridines on Silver Catalysts

Electroreduction of carbon dioxide to formate using highly efficient bimetallic Sn–Pd aerogels

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Product

Resources

About

Heterogeneous Molecular Catalysts of Metal Phthalocyanines for Electrochemical CO₂ Reduction Reactions

Heterogeneous Molecular Catalysts of Metal Phthalocyanines for Electrochemical CO₂ Reduction Reactions

CO₂ Electrolysis via Surface-Engineering Electrografted Pyridines on Silver Catalysts