Multiple C–C bond formation upon electrocatalytic reduction of CO<sub>2</sub> by an iron-based molecular macrocycle

Dong, Si-Thanh; Xu, Chen; Lassalle‐Kaiser, Benedikt

doi:10.1039/d2sc04729b

Cited by 12 publications

(38 citation statements)

References 44 publications

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“…The low activation energies for more reduced complexes, on the other hand, indicate that H 2 is produced over PcFe("0") and PcFe("-I"). Therefore, H 2 is, in line with experimental evidence, 16 likely to be formed at applied potentials lower than −0.7 V.…”

Section: ■ Computational Detailssupporting

confidence: 83%

“…Therefore, more negative potentials shift the selectivity from CO toward post-CO products, which is observed experimentally. 16 PcFe−COH formation is unlikely due to the very low potential of almost −2.10 V independent of the formal oxidation state (see Supporting Information). The hydrogenation of PcFe−CO to form PcFe−CHO has a potential of approximately 0 V for all oxidation states (Figure 4; right arrow).…”

Section: ■ Computational Detailsmentioning

confidence: 99%

“…This is, however, contrary to the experiment, which indicates that, irrespective of the applied potential, always the amount of CO is significantly higher than that of post-CO products. 16 Thus, the activation energy cannot solely explain the observed selectivity. Indeed, the proton supply is highly limited by the very low concentration of H 3 O + at pH = 7 ([H + ] = 10 −7 ).…”

Section: ■ Computational Detailsmentioning

confidence: 99%

“…However, our previous study 16 surprisingly demonstrated that C 2+ products can also be formed over single-atom molecular catalysts like iron phthalocyanine (PcFe) albeit with a very low faradaic efficiency, while these systems are wellknown to only produce C1 products. 17,18 Based on the abovementioned study, 16 PcFe is capable of producing light hydrocarbons such as C 2 H 4 and C 3 H 6 through the electrocatalytic CO 2 reduction in aqueous solutions under neutral pH conditions. Based on their experimental evaluations, we suggested that CO is an essential reactant in the pathways of CO 2 reduction to C 2+ .…”

Section: ■ Introductionmentioning

confidence: 99%

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Mechanism of CO₂ Electroreduction to Multicarbon Products over Iron Phthalocyanine Single-Atom Catalysts

Khakpour,

Farshadfar,

Dong

et al. 2024

J. Phys. Chem. C

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Carbon dioxide reduction reaction (CO 2 RR) is a promising method for converting CO 2 into value-added products. CO 2 RR over single-atom catalysts (SACs) is widely known to result in chemical compounds such as carbon monoxide and formic acid that contain only one carbon atom (C1). Indeed, at least two active sites are commonly believed to be required for C−C coupling to synthesize compounds, such as ethanol and propylene (C 2+ ), from CO 2 . However, experimental evidence suggests that iron phthalocyanine (PcFe), which possesses only a single metal center, can produce a trace amount of C 2+ products. To the best of our knowledge, the mechanism by which C 2+ products are formed over a SAC such as PcFe is still unknown. Using density functional theory (DFT), we analyzed the mechanism of the CO 2 RR to C1 and C 2+ products over PcFe. Due to the high concentration of bicarbonate at pH 7, CO 2 RR competes with HCO 3 − reduction. Our computations indicate that bicarbonate reduction is significantly more favorable. However, the rate of this reaction is influenced by the H 3 O + concentration. For the formation of C 2+ products, our computations reveal that C−C coupling proceeds through the reaction between in situ-formed CO and PcFe("0")−CH 2 or PcFe("-I")−CH 2 intermediates. This reaction step is highly exergonic and requires only low activation energies of 0.44 and 0.24 eV for PcFe("0")−CH 2 and PcFe("-I")−CH 2 . The DFT results, in line with experimental evidence, suggest that C 2+ compounds are produced over PcFe at low potentials whereas CH 4 is still the main post-CO product.

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Section: ■ Computational Detailssupporting

confidence: 83%

Section: ■ Computational Detailsmentioning

confidence: 99%

Section: ■ Computational Detailsmentioning

confidence: 99%

Section: ■ Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Mechanism of CO₂ Electroreduction to Multicarbon Products over Iron Phthalocyanine Single-Atom Catalysts

Khakpour,

Farshadfar,

Dong

et al. 2024

J. Phys. Chem. C

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“…Furthermore, recent examples of C 2+ products stemming from molecular catalysts opens routes to tune multicarbon selectivity through ligand and metal modifications. 84 Aside from CO-based tandem pathways common to Cu catalysts, other metals have recently demonstrated C 2 -C 4 production in cascade pathways stemming from formate-pathway intermediates rather than those that generate CO, and could therefore be utilised in tandem catalysis based on alternative primary products. [85][86][87] When comparing multi-cell with single-cell tandems, there are a number of different considerations.…”

Section: Nanoscale Minireviewmentioning

confidence: 99%

Multiscale effects in tandem CO₂ electrolysis to C₂₊ products

Cousins,

Creissen

2024

Nanoscale

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Operando Spectroelectrochemistry Unravels the Mechanism of CO₂ Electrocatalytic Reduction by an Fe Porphyrin

Salamé,

Hon Cheah,

Bonin

et al. 2024

Angewandte Chemie

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Iron porphyrins are molecular catalysts recognized for their ability to electrochemically and photochemically reduce carbon dioxide (CO2). The main reduction product is carbon monoxide (CO). CO holds significant industrial importance as it serves as a precursor for various valuable chemical products containing either a single carbon atom (C1), like methanol or methane, or multiple carbon atoms (Cn), such as ethanol or ethylene. Despite the long‐established efficiency of these catalysts, optimizing their catalytic activity and stability and comprehending the intricate reaction mechanisms remain a significant challenge. This article presents a comprehensive investigation of the mechanistic aspects of the selective electroreduction of CO2 to CO using an iron porphyrin substituted with four trimethylammonium groups in the para position [(pTMA)FeIII‐Cl]4+. By employing infrared and UV‐Visible spectroelectrochemistry, changes in the electronic structure and coordination environment of the iron center can be observed in real‐time as the electrochemical potential is adjusted, offering new insights into the reaction mechanisms. Catalytic species were identified, and evidence of a secondary reaction pathway was uncovered, potentially prompting a re‐evaluation of the nature of the catalytically active species.

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Multiple C–C bond formation upon electrocatalytic reduction of CO₂ by an iron-based molecular macrocycle

Abstract: Molecular macrocycles are very promising electrocatalysts for the reduction of carbon dioxide into value-added chemicals. Up to now, most of these catalysts produced only C1 products. We report here that...

Cited by 12 publications

References 44 publications

Mechanism of CO₂ Electroreduction to Multicarbon Products over Iron Phthalocyanine Single-Atom Catalysts

Mechanism of CO₂ Electroreduction to Multicarbon Products over Iron Phthalocyanine Single-Atom Catalysts

Multiscale effects in tandem CO₂ electrolysis to C₂₊ products

Operando Spectroelectrochemistry Unravels the Mechanism of CO₂ Electrocatalytic Reduction by an Fe Porphyrin

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Multiple C–C bond formation upon electrocatalytic reduction of CO2 by an iron-based molecular macrocycle

Abstract: Molecular macrocycles are very promising electrocatalysts for the reduction of carbon dioxide into value-added chemicals. Up to now, most of these catalysts produced only C1 products. We report here that...

Cited by 12 publications

References 44 publications

Mechanism of CO2 Electroreduction to Multicarbon Products over Iron Phthalocyanine Single-Atom Catalysts

Mechanism of CO2 Electroreduction to Multicarbon Products over Iron Phthalocyanine Single-Atom Catalysts

Multiscale effects in tandem CO2 electrolysis to C2+ products

Operando Spectroelectrochemistry Unravels the Mechanism of CO2 Electrocatalytic Reduction by an Fe Porphyrin

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Multiple C–C bond formation upon electrocatalytic reduction of CO₂ by an iron-based molecular macrocycle

Mechanism of CO₂ Electroreduction to Multicarbon Products over Iron Phthalocyanine Single-Atom Catalysts

Mechanism of CO₂ Electroreduction to Multicarbon Products over Iron Phthalocyanine Single-Atom Catalysts

Multiscale effects in tandem CO₂ electrolysis to C₂₊ products

Operando Spectroelectrochemistry Unravels the Mechanism of CO₂ Electrocatalytic Reduction by an Fe Porphyrin