Behavior of a Cu-Peptide complex under water oxidation conditions – Molecular electrocatalyst or precursor to nanostructured CuO films?

Lukács, Dávid; Németh, Miklós; Szyrwiel, Łukasz; Illés, Levente; Pécz, B.; Shen, Shaohua; Pap, József S.

doi:10.1016/j.solmat.2019.110079

Cited by 9 publications

(7 citation statements)

References 47 publications

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“…We propose CuO x as a plausible contributor to the observed high-performance catalysis. Recently, the design and synthesis of copper molecular catalysts have attracted significant attention. − The following findings shed new light on the assessment of Cu-complexes and related molecular agents as OER catalysts. Our combined approach of advanced microscopy techniques and complementary spectroscopic investigations is intended to inspire a thorough operando revision of other key homogeneous molecular-catalyst systems to establish their true active species.…”

Section: Introductionmentioning

confidence: 97%

“…Water splitting is a sustainable approach to energy storage and conversion. − The oxygen-evolution reaction (OER) is the bottleneck for water splitting, and many metal compounds have been used as OER catalysts. − Among the wide range of homogeneous OER catalysts, copper(II) complexes are particularly promising. − However, the mechanisms of OER assisted by copper(II) complexes are very complicated. − ,− In some cases, in the presence of copper(II) complexes, copper oxide is detected. − ,− In 1981, Cu complexes with bipyridyl or sulfonated phthalocyanines were first shown to be efficient OER catalysts − in the presence of Ru(bpy) 3 3+ in both alkaline and weakly acidic media . However, Du’s group first revealed that nanosized electrodeposited copper oxides were the true catalysts for OER in the presence of a mononuclear copper(II) complex ([Cu II (TPA)H 2 O](ClO 4 ) 2 (TPA = tris(2-pyridylmethyl)amine)) during long-time operations and in alkaline conditions .…”

Section: Introductionmentioning

confidence: 99%

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Mechanistic Understanding of Water Oxidation in the Presence of a Copper Complex by In Situ Electrochemical Liquid Transmission Electron Microscopy

Balaghi

Mehrabani

Mousazade

et al. 2021

ACS Appl. Mater. Interfaces

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The design of molecular oxygen-evolution reaction (OER) catalysts requires fundamental mechanistic studies on their widely unknown mechanisms of action. To this end, copper complexes keep attracting interest as good catalysts for the OER, and metal complexes with TMC (TMC = 1,4,8,11-tetramethyl-1,4,8,11-tetraazacyclotetradecane) stand out as active OER catalysts. A mononuclear copper complex, [Cu(TMC)(H2O)](NO3)2 (TMC = 1,4,8,11-tetramethyl-1,4,8,11-tetraazacyclotetradecane), combined both key features and was previously reported to be one of the most active copper-complex-based catalysts for electrocatalytic OER in neutral aqueous solutions. However, the functionalities and mechanisms of the catalyst are still not fully understood and need to be clarified with advanced analytical studies to enable further informed molecular catalyst design on a larger scale. Herein, the role of nanosized Cu oxide particles, ions, or clusters in the electrochemical OER with a mononuclear copper(II) complex with TMC was investigated by operando methods, including in situ vis-spectroelectrochemistry, in situ electrochemical liquid transmission electron microscopy (EC-LTEM), and extended X-ray absorption fine structure (EXAFS) analysis. These combined experiments showed that Cu oxide-based nanoparticles, rather than a molecular structure, are formed at a significantly lower potential than required for OER and are candidates for being the true OER catalysts. Our results indicate that for the OER in the presence of a homogeneous metal complex-based (pre)catalyst, careful analyses and new in situ protocols for ruling out the participation of metal oxides or clusters are critical for catalyst development. This approach could be a roadmap for progress in the field of sustainable catalysis via informed molecular catalyst design. Our combined approach of in situ TEM monitoring and a wide range of complementary spectroscopic techniques will open up new perspectives to track the transformation pathways and true active species for a wide range of molecular catalysts.

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Section: Introductionmentioning

confidence: 97%

Section: Introductionmentioning

confidence: 99%

Mechanistic Understanding of Water Oxidation in the Presence of a Copper Complex by In Situ Electrochemical Liquid Transmission Electron Microscopy

Balaghi

Mehrabani

Mousazade

et al. 2021

ACS Appl. Mater. Interfaces

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“…The complexfree Nf-DC@ITO or FTO electrodes exhibited minimal current at this potential (inset of Figure 4a). When 2-ED@FTO has been applied as the working electrode, the reaction was stopped after 3.5 h (the 1st run in the inset of Figure 4d), and a sample was taken from the headspace, and the evolved O 2 gas was quantified by gas chromatography (for technical details, see our earlier publications [25,29,32]). The overall passed charge was 16.4 C; thus, the theoretical maximum for O 2 was 42.4 µmol (n = Q/4F).…”

Section: Performance Of the Differently Fabricated Immobilized Samples Of 1 And 2 In Water Oxidationmentioning

confidence: 99%

Electrodeposition of Fe-Complexes on Oxide Surfaces for Efficient OER Catalysis

et al. 2021

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Progress in non-covalent/self-assembled immobilization methods on (photo)electrode materials for molecular catalysts could broaden the scope of attainable systems. While covalent linkage (though considered more stable) necessitates functional groups introduced by means of often cumbersome synthetic procedures, non-covalent assemblies require sufficient propensity of the molecular unit for surface adsorption, thus set less rigorous pre-requisites. Herein, we report efficient electrodeposition (ED) of two Fe(III) complexes prepared with closely related NN’N pincer ligands yielding stable and active ad-layers for the electrocatalysis of the oxygen-evolving reaction (OER). The ED method is based on the utilization of a chloride precursor complex [FeIIICl2(NN’N)], which is dissolved in an organic electrolyte undergoes chloride/aqua ligand exchange upon addition of water. ED provides patchy distribution of a chloride-depleted catalyst layer on indium tin oxide (ITO) and fluorine-doped tin oxide (FTO) surfaces, which can be applied for long periods as OER electrocatalysts. Compared to drop-casting or layering of [FeIIICl2(NN’N)] with Nafion (a commonly used support for molecular electrocatalysts), the surface modification by ED is a material saving and efficient method to immobilize catalysts.

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“…This mechanism may be conceived as that shown in Scheme 19 (cycle on the bottom). In the key step, the 2e − oxidized form, Cu III -O • attacks a hydroxyl group on the coordinated (HO) 3 BO − ligand providing an energetically favorable pathway for the O−O bond formation.In the presence of different N-donor ligands (for example, 2,2'-bypyridine, various tripeptides and a dinucleating peptidomimetic ligand) borate was also reported to coordinate to copper(Huang et al 2017;Lukács et al 2019;Ruan et al 2021). However, the outcome of the electrochemical oxidation seems to depend strongly on the ancillary ligand.…”

mentioning

confidence: 99%

“…However, the outcome of the electrochemical oxidation seems to depend strongly on the ancillary ligand. In the case of mononucleating tripeptides the formation of [LCu III -OOB(OH) 3 ] 2− has been proposed upon electrochemical oxidation, leading to complex degradation and in situ 'CuO' deposition(Lukács et al 2019). As for the di-copper complex formed with the peptidomimetic ligand results implied that borate coordination occurred upon Cu II →Cu III oxidation(Ruan et al 2021).…”

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confidence: 99%

Perspectives of Redox-Active Ligands in Artificial Photosynthesis

Benkó

Lukács

et al. 2022

Preprint

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Organic ancillary ligands can cooperate with metal centers in different ways in molecular catalysts of the very important oxygen evolving reaction. In this overview, we focus on what can be gained of such a cooperation and bring examples on the possible useful outcomes of redox state changes in ancillary ligands. Analogies are also highlighted if apply, with the cooperation between the natural oxygen evolving complex and the redox-mediating Tyrosine-Histidine pairs found in photosystem II.

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Behavior of a Cu-Peptide complex under water oxidation conditions – Molecular electrocatalyst or precursor to nanostructured CuO films?

Cited by 9 publications

References 47 publications

Mechanistic Understanding of Water Oxidation in the Presence of a Copper Complex by In Situ Electrochemical Liquid Transmission Electron Microscopy

Mechanistic Understanding of Water Oxidation in the Presence of a Copper Complex by In Situ Electrochemical Liquid Transmission Electron Microscopy

Electrodeposition of Fe-Complexes on Oxide Surfaces for Efficient OER Catalysis

Perspectives of Redox-Active Ligands in Artificial Photosynthesis

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