Heterogeneous Water Oxidation Catalysts for Molecular Anodes and Photoanodes

Sheridan, Matthew V.; Sherman, Benjamin D.; Xie, Yi; Wang, Ying

doi:10.1002/solr.202000565

Cited by 6 publications

(6 citation statements)

References 116 publications

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“…Past research on catalytic water oxidation has generally focused on the development of heterogeneous and homogeneous (molecular) WOCs, [10–13] with the latter exhibiting certain vital advantages over the former:…”

Section: Introductionmentioning

confidence: 99%

“…Past research on catalytic water oxidation has generally focused on the development of heterogeneous and homogeneous (molecular) WOCs, [10][11][12][13] with the latter exhibiting certain vital advantages over the former: (1) The redox and electronic properties of the metal center in molecular WOCs (MWOCs) can be fine-tuned by ligand structure modification. [7,14,15] (2) Homogeneous solutions enable the elucidation of catalytic mechanisms using spectroscopic techniques, which benefits the design of ideal catalysts.…”

Section: Introductionmentioning

confidence: 99%

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Homogeneous Water Oxidation Catalyzed by First‐Row Transition Metal Complexes: Unveiling the Relationship between Turnover Frequency and Reaction Overpotential

Wang

Hsu

2022

ChemSusChem

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The utilization of earth‐abundant low‐toxicity metal ions in the construction of highly active and efficient molecular catalysts promoting the water oxidation reaction is important for developing a sustainable artificial energy cycle. However, the kinetic and thermodynamic properties of the currently available molecular water oxidation catalysts (MWOCs) have not been comprehensively investigated. This Review summarizes the current status of MWOCs based on first‐row transition metals in terms of their turnover frequency (TOF, a kinetic property) and overpotential (η, a thermodynamic property) and uses the relationship between log(TOF) and η to assess catalytic performance. Furthermore, the effects of the same ligand classes on these MWOCs are discussed in terms of TOF and η, and vice versa. The collective analysis of these relationships provides a metric for the direct comparison of catalyst systems and identifying factors crucial for catalyst design.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Homogeneous Water Oxidation Catalyzed by First‐Row Transition Metal Complexes: Unveiling the Relationship between Turnover Frequency and Reaction Overpotential

Wang

Hsu

2022

ChemSusChem

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“…As such, research into the development and Current catalysts do not satisfy the need for cost efficiency, activity, and stability for this endergonic reaction; currently available catalysts suffer from limited catalytic activity due to significant overpotentials (≥400 mV). As such, research into the development and design of sufficiently stable and efficient catalysts capable of facilitating solar−driven water oxidation has grown significantly in recent years [10][11][12][13][14][15][16].…”

Section: Introductionmentioning

confidence: 99%

Computational Analysis of Structure–Activity Relationships in Highly Active Homogeneous Ruthenium−Based Water Oxidation Catalysts

Bury

Pushkar

2022

Catalysts

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Linear free−energy scaling relationships (LFESRs) and regression analysis may predict the catalytic performance of heterogeneous and recently, homogenous water oxidation catalysts (WOCs). This study analyses thirteen homogeneous Ru−based catalysts—some, the most active catalysts studied: the Ru(tpy−R)(QC) and Ru(tpy−R)(4−pic)2 complexes, where tpy is 2,2’;6’,2”terpyridine, QC is 8−quinolinecarboxylate and 4−pic is 4−picoline. Typical relationships studied among heterogenous catalysts cannot be applied to homogeneous catalysts. The selected group of structurally similar catalysts with impressive catalytic activity deserves closer computational and statistical analysis of multiple reaction step energetics correlating with measured catalytic activity. We report general methods of LFESR analysis yield insufficiently robust relationships between descriptor variables. However, volcano−plot−based analysis grounded in Sabatier’s principle reveals ideal relative energies of the RuIV = O and RuIV−OH intermediates and optimal changes in free energies of water nucleophilic attack on RuV = O. A narrow range of RuIV−OH to RuV = O redox potentials corresponding with the highest catalytic activities suggests facile access to the catalytically competent high−valent RuV = O state, often inaccessible from RuIV = O. Our work incorporates experimental oxygen evolution rates into approaches of LFESR and Sabatier−principle−based analysis, identifying a narrow yet fertile energetic landscape to bountiful oxygen evolution activity, leading to future rational design.

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“…Recently, research efforts have focused on the preparation of supported electrocatalysts by anchoring molecular catalysts directly to an electrode or to a carbon support using covalent and noncovalent attachment methods. − Several examples have been reported for the synthesis of cobalt-heterogenized catalysts for water oxidation via van der Waals interactions between a cobalt complex with long alkyl chains and fluorine-doped tin oxide (FTO) or carbon electrodes (see, for example, g in Scheme ). − Supported Co II phthalocyanine complexes are efficient molecular water oxidation electrocatalysts at pH 7 when physiosorbed onto FTO ( h , Scheme ) or at basic pH (1 M KOH) when π–π-stacked onto carbon nanotubes .…”

Section: Introductionmentioning

confidence: 99%

Immobilization of “Capping Arene” Cobalt(II) Complexes on Ordered Mesoporous Carbon for Electrocatalytic Water Oxidation

et al. 2021

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We report the synthesis, characterization, and electrocatalytic water oxidation activity of two cobalt complexes, (6-FP)Co(NO 3 ) 2 (1) (6-FP = 8,8′-(1,2phenylene)diquinoline) and (5-FP)Co(NO 3 ) 2 (2) (5-FP = 1,2-bis(N-7-azaindolyl)benzene), containing "capping arene" bidentate ligands with nitrogen atom donors. The cobalt complexes 1 and 2 were supported on ordered mesoporous carbon (OMC) by π−π stacking, resulting in heterogenized cobalt materials 6-FP-Co-OMC-1 and 5-FP-Co-OMC-2, respectively, and studied for electrocatalytic water oxidation. We find that 6-FP-Co-OMC-1 exhibits an overpotential of 355 mV for a current density of 10 mA cm −2 and a turnover frequency (TOF) of ∼0.53 s −1 at an overpotential of 400 mV at pH 14. 6-FP-Co-OMC-1 exhibits activity that is ∼1.6 times that of 5-FP-Co-OMC-2, which gives a TOF of 0.32 s −1 at 400 mV overpotential. The structural stability of the single-atom Co site was demonstrated for 6-FP-Co-OMC-1 using X-ray absorption spectroscopy for the molecular complex supported on OMC, but slow degradation in catalyst activity can be attributed to eventual formation of Co oxide clusters. DFT computations of electrocatalytic water oxidation using the molecular complexes as models provide a description of the catalytic mechanism. These studies reveal that the mechanism for O−O bond formation involves an intermediate Co IV oxo complex that undergoes an intramolecular reductive O−O coupling to form a Co II − OOH species. Further, the calculations predict that the molecular 6-FP-Co structure is more active for electrocatalytic water oxidation than 5-FP-Co, which is consistent with experimental studies of 6-FP-Co-OMC-1 and 5-FP-Co-OMC-2, highlighting the possibility that the ligand structure influences the catalytic activity of the supported molecular catalysts.

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Heterogeneous Water Oxidation Catalysts for Molecular Anodes and Photoanodes

Cited by 6 publications

References 116 publications

Homogeneous Water Oxidation Catalyzed by First‐Row Transition Metal Complexes: Unveiling the Relationship between Turnover Frequency and Reaction Overpotential

Homogeneous Water Oxidation Catalyzed by First‐Row Transition Metal Complexes: Unveiling the Relationship between Turnover Frequency and Reaction Overpotential

Computational Analysis of Structure–Activity Relationships in Highly Active Homogeneous Ruthenium−Based Water Oxidation Catalysts

Immobilization of “Capping Arene” Cobalt(II) Complexes on Ordered Mesoporous Carbon for Electrocatalytic Water Oxidation

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