Influence of the spatial distribution of copper sites on the selectivity of the oxygen reduction reaction

Smits, Nicole W. G.; Rademaker, Dana; Коновалов, А. И.; Siegler, Maxime A.; Hetterscheid, Dennis G. H.

doi:10.1039/d1dt03296h

Cited by 21 publications

(38 citation statements)

References 82 publications

(120 reference statements)

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“…In addition to the ORR, the catalytic activity of [Cu 2 L(μ-OH)] 3+ for the hydrogen peroxide reduction reaction (HPRR) is of interest because H 2 O 2 is found as a detectable intermediate in the aqueous electrochemical ORR mechanism of other copper complexes with tetradentate pyridylamine ligands that is formed after the two-electron reduction of oxygen. 36,39,41,53,54 In the presence of 1.1 mM H 2 O 2 , which is the same concentration as the maximum solubility of oxygen in PB, a catalytic wave was observed with a slightly earlier onset than the ORR (Figure 3b). As this earlier onset is only present in the first scan, we contribute this occurrence to the weak binding of H 2 O 2 to the oxidized form of the catalyst, although such a species could not be detected by other techniques like NMR.…”

Section: Cyclic Voltammetry Of [Cu 2 L(μ-oh)] 3+mentioning

confidence: 99%

“…On the other hand, electrochemical studies that have reported the ORR activity of homogeneous metal complexes with two [36][37][38] or even three 37,39,40 copper atoms in aqueous solutions all lack evidence that direct cooperativity between the copper centers takes place during catalysis. The lack of cooperativity can be explained by the fact that covalently linking copper sites will not invariably result in synergy between the metal centers.…”

Section: Introductionmentioning

confidence: 99%

“…For instance, not all metal centers might participate during catalysis, 37 the copper sites can turn away from each other, 36 the catalyst can decompose during electrocatalysis, 38 or multiple copper centers in close proximity will result in a change of selectivity, but not due to direct metal-metal cooperativity. 39 An exception is a study by Yu and co-workers, in which three copper centers are forced closely together improving the selectivity of the ORR, although a full characterization of the active species and a catalytic mechanism are absent. 40 To address our research question, we set out to study the ORR activity of a complex with a rigid ligand framework that can coordinate two copper atoms in close proximity and, in addition, to study in detail the nature of the active species along the catalytic cycle.…”

Section: Introductionmentioning

confidence: 99%

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Mechanistic Investigations into the Selective Reduction of Oxygen by a MCO T3 site-inspired Copper Complex

Langevelde

Kounalis

Killian

et al. 2022

Preprint

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Understanding how multicopper oxidases (MCOs) efficiently and selectively reduce oxygen in the trinuclear copper cluster (TNC) is of great importance. Previously it was reported that when the T2-site is removed from the TNC, all O2 binding activity at the dinuclear T3-site is lost. Computational studies attribute this loss of activity to the flexibility of the protein active site, where the T3-copper centers move apart to minimize electrostatic repulsions. To address the question if and how a more constrained T3-site will catalyze the reduction of oxygen, we herein report a mechanistic investigation into the oxygen reduction reaction (ORR) activity of the dinuclear copper complex [Cu2L(μ-OH)]3+ (L=2,7-bis[bis(2-pyridylmethyl)aminomethyl]-1,8-naphthyridine). This T3-inspired complex confines the Cu centers in a rigid scaffold in close proximity instead of the flexible scaffold found in the protein active site and we demonstrate that under these constraints the dinuclear copper site displays ORR activity. Compared to the ORR mechanism of MCOs, we show that electrochemical reduction of [Cu2L(μ-OH)]3+ follows a similar pathway as the reduction of the resting enzyme due to the presence of the Cu-OH-Cu motif. By identification of key intermediates along the catalytic cycle of [Cu2L(μ-OH)]3+ we provide for the first time evidence that metal-metal cooperativity takes place during electrocatalysis of the ORR by a copper-based catalyst, which is achieved by the ability of the rigid ligand framework to bind two copper atoms in close proximity. Electrochemical studies show that the mechanisms of the ORR and hydrogen peroxide reduction reaction (HPRR) found for [Cu2L(μ-OH)]3+ are different from the ones found for analogous mononuclear copper catalysts. In addition, the metal-metal cooperativity results in an improved selectivity for the four-electron ORR of more than 70%. This selectivity is achieved by better stabilization of reaction intermediates between both copper centers, which is also essential for the ORR mechanism observed in MCOs. Overall, the mechanism of the [Cu2L(μ-OH)]3+-catalyzed ORR in this work gives insight into the ORR activity of a T3-site and contributes to understanding of how the ORR activity and selectivity are established in MCOs.

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Section: Cyclic Voltammetry Of [Cu 2 L(μ-oh)] 3+mentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Mechanistic Investigations into the Selective Reduction of Oxygen by a MCO T3 site-inspired Copper Complex

Langevelde

Kounalis

Killian

et al. 2022

Preprint

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“…The electronic structure and electrochemical characterization can be changed, which is beneficial for the ORR performance. [6][7][8] In recent years, covalent triazine frameworks (CTFs) have been utilized for a broad range of applications, including gas separation and storage, chemical sensing and catalysts, owing to their unique physicochemical properties. 9,10 In addition, most CTF materials have a porous structure, abundant heteroatomic sites and a large proportion of nitrogen species, which gives CTF materials potential for use as efficient ORR electrocatalysts.…”

Section: Introductionmentioning

confidence: 99%

“…The electronic structure and electrochemical characterization can be changed, which is beneficial for the ORR performance. 6–8…”

Section: Introductionmentioning

confidence: 99%

Heteroatom-doped carbon materials derived from covalent triazine framework@MOFs for the oxygen reduction reaction

Zhang

Lan

et al. 2022

Dalton Trans.

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Oxygen reduction catalysis by [Cu(cyclen)Cl]Cl·H₂O: The relationship of selectivity to proton in nonaqueous solution and aqueous solution

Zhang,

Qi,

Yang

et al. 2023

Applied Organom Chemis

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The reaction of 1,4,7,10‐tetraazacyclododecane (cyclen) with CuCl2·2H2O results in a novel five‐coordinated mononuclear copper complex, [Cu(cyclen)Cl]Cl·H2O, which has been characterized using physicochemical and spectroscopic methods. This copper complex can serve as a catalyst for oxygen reduction reactions (ORRs). The selectivity for 4e−/4H+ reduction to H2O νersus 2e−/2H+ reduction to H2O2 is determined by the relationship of the pKa value of the proton donor in nonaqueous solutions. The dissociation of Cl− from [Cu(cyclen)Cl]Cl·H2O creates an empty position on the copper centre, enabling to binding of dioxygen (O2) to form Cu(II)‐superoxo intermediate, which further reacts with a strong acid as a proton donor to form H2O and with a weak acid as a proton donor to form H2O2. Moreover, the faradaic efficiency for H2O2 production increases in an aqueous environment with the increase of pH.

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Influence of the spatial distribution of copper sites on the selectivity of the oxygen reduction reaction

Abstract: Moving towards a hydrogen economy raises the demand for affordable and efficient catalysts for the oxygen reduction reaction. Cu-bmpa (bmpa = bis(2-picolyl)amine) is shown to have moderate activity, but poor...

Cited by 21 publications

References 82 publications

Mechanistic Investigations into the Selective Reduction of Oxygen by a MCO T3 site-inspired Copper Complex

Mechanistic Investigations into the Selective Reduction of Oxygen by a MCO T3 site-inspired Copper Complex

Heteroatom-doped carbon materials derived from covalent triazine framework@MOFs for the oxygen reduction reaction

Oxygen reduction catalysis by [Cu(cyclen)Cl]Cl·H₂O: The relationship of selectivity to proton in nonaqueous solution and aqueous solution

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Influence of the spatial distribution of copper sites on the selectivity of the oxygen reduction reaction

Abstract: Moving towards a hydrogen economy raises the demand for affordable and efficient catalysts for the oxygen reduction reaction. Cu-bmpa (bmpa = bis(2-picolyl)amine) is shown to have moderate activity, but poor...

Cited by 21 publications

References 82 publications

Mechanistic Investigations into the Selective Reduction of Oxygen by a MCO T3 site-inspired Copper Complex

Mechanistic Investigations into the Selective Reduction of Oxygen by a MCO T3 site-inspired Copper Complex

Heteroatom-doped carbon materials derived from covalent triazine framework@MOFs for the oxygen reduction reaction

Oxygen reduction catalysis by [Cu(cyclen)Cl]Cl·H2O: The relationship of selectivity to proton in nonaqueous solution and aqueous solution

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Oxygen reduction catalysis by [Cu(cyclen)Cl]Cl·H₂O: The relationship of selectivity to proton in nonaqueous solution and aqueous solution