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McCarthy, B. D., Beiler, A. M., Johnson, B. A., Liseev, T., Castner, A. T. & Ott, S. (2020). Analysis of electrocatalytic metal-organic frameworks. Coordination chemistry reviews, 406, Article ID 213137.
Open this publication in new window or tab >>Analysis of electrocatalytic metal-organic frameworks
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2020 (English)In: Coordination chemistry reviews, ISSN 0010-8545, E-ISSN 1873-3840, Vol. 406, article id 213137Article, review/survey (Refereed) Published
Abstract [en]

The electrochemical analysis of molecular catalysts for the conversion of bulk feedstocks into energy-rich clean fuels has seen dramatic advances in the last decade. More recently, increased attention has focused on the characterization of metal-organic frameworks (MOFs) containing well-defined redox and catalytically active sites, with the overall goal to develop structurally stable materials that are industrially relevant for large-scale solar fuel syntheses. Successful electrochemical analysis of such materials draws heavily on well-established homogeneous techniques, yet the nature of solid materials presents additional challenges. In this tutorial-style review, we cover the basics of electrochemical analysis of electroactive MOFs, including considerations of bulk stability, methods of attaching MOFs to electrodes, interpreting fundamental electrochemical data, and finally electrocatalytic kinetic characterization. We conclude with a perspective of some of the prospects and challenges in the field of electrocatalytic MOFs. 

Place, publisher, year, edition, pages
ELSEVIER SCIENCE SA, 2020
Keywords
Metal-organic frameworks, Electrochemistry, Electrocatalysis, Electroactive thin films
National Category
Inorganic Chemistry Physical Chemistry
Identifiers
urn:nbn:se:uu:diva-407107 (URN)10.1016/j.ccr.2019.213137 (DOI)000510959500004 ()
Funder
EU, European Research Council, ERC-CoG2015-681895_MOFcatSwedish Energy AgencyStiftelsen Olle Engkvist Byggmästare
Available from: 2020-03-19 Created: 2020-03-19 Last updated: 2020-03-19Bibliographically approved
Materna, K. L., Lalaoui, N., Laureanti, J. A., Walsh, A. P., Pettersson-Rimgard, B., Lomoth, R., . . . Hammarström, L. (2020). Using Surface Amide Couplings to Assemble Photocathodes for Solar Fuel Production Applications. ACS Applied Materials and Interfaces, 12(4), 4501-4509
Open this publication in new window or tab >>Using Surface Amide Couplings to Assemble Photocathodes for Solar Fuel Production Applications
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2020 (English)In: ACS Applied Materials and Interfaces, ISSN 1944-8244, E-ISSN 1944-8252, Vol. 12, no 4, p. 4501-4509Article in journal (Refereed) Published
Abstract [en]

A facile surface amide-coupling method was examined to attach dye and catalyst molecules to silatrane-decorated NiO electrodes. Using this method, electrodes with a push-pull dye were assembled and characterized by photoelectrochemistry and transient absorption spectroscopy. The dye-sensitized electrodes exhibited hole injection into NiO and good photoelectrochemical stability in water, highlighting the stability of the silatrane anchoring group and the amide linkage. The amide-coupling protocol was further applied to electrodes that contain a molecular proton reduction catalyst for use in photocathode architectures. Evidence for catalyst reduction was observed during photoelectrochemical measurements and via photocathodes.

Place, publisher, year, edition, pages
AMER CHEMICAL SOC, 2020
Keywords
solar fuels, photocathode, nickel oxide, silatrane, amide coupling
National Category
Physical Chemistry
Identifiers
urn:nbn:se:uu:diva-406495 (URN)10.1021/acsami.9b19003 (DOI)000510532000032 ()31872996 (PubMedID)
Funder
Swedish Energy Agency, 11674-8
Available from: 2020-03-11 Created: 2020-03-11 Last updated: 2020-03-11Bibliographically approved
Wang, S., Pullen, S., Weippert, V., Liu, T., Ott, S., Lomoth, R. & Hammarström, L. (2019). Direct Spectroscopic Detection of Key Intermediates and Turnover Process in Catalytic H2 Formation by a Biomimetic Diiron Catalyst. Chemistry - A European Journal, 25(47), 11135-11140
Open this publication in new window or tab >>Direct Spectroscopic Detection of Key Intermediates and Turnover Process in Catalytic H2 Formation by a Biomimetic Diiron Catalyst
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2019 (English)In: Chemistry - A European Journal, ISSN 0947-6539, E-ISSN 1521-3765, Vol. 25, no 47, p. 11135-11140Article in journal (Refereed) Published
Abstract [en]

[FeFe(Cl-2-bdt)(CO)(6)] (1; Cl-2-bdt=3,6-dichlorobenzene-1,2-dithiolate), inspired by the active site of FeFe-hydrogenase, shows a chemically reversible 2 e(-) reduction at -1.20 V versus the ferrocene/ferrocenium couple. The rigid and aromatic bdt bridging ligand lowers the reduction potential and stabilizes the reduced forms, compared with analogous complexes with aliphatic dithiolates; thus allowing details of the catalytic process to be characterized. Herein, time-resolved IR spectroscopy is used to provide kinetic and structural information on key catalytic intermediates. This includes the doubly reduced, protonated complex 1H(-), which has not been previously identified experimentally. In addition, the first direct spectroscopic observation of the turnover process for a molecular H-2 evolving catalyst is reported, allowing for straightforward determination of the turnover frequency.

National Category
Physical Chemistry
Identifiers
urn:nbn:se:uu:diva-380278 (URN)10.1002/chem.201902100 (DOI)000479841700001 ()31210385 (PubMedID)
Funder
Swedish Research Council, 2016-04271Stiftelsen Olle Engkvist Byggmästare, 2016/3
Available from: 2019-03-26 Created: 2019-03-26 Last updated: 2019-10-31Bibliographically approved
Roy, S., Huang, Z., Bhunia, A., Castner, A., Gupta, A. K., Zou, X. & Ott, S. (2019). Electrocatalytic Hydrogen Evolution from a Cobaloxime-Based Metal-Organic Framework Thin Film. Journal of the American Chemical Society, 141(40), 15942-15950
Open this publication in new window or tab >>Electrocatalytic Hydrogen Evolution from a Cobaloxime-Based Metal-Organic Framework Thin Film
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2019 (English)In: Journal of the American Chemical Society, ISSN 0002-7863, E-ISSN 1520-5126, Vol. 141, no 40, p. 15942-15950Article in journal (Refereed) Published
Abstract [en]

Molecular hydrogen evolution catalysts (HECs) are synthetically tunable and often exhibit high activity, but they are also hampered by stability concerns and practical limitations associated with their use in the homogeneous phase. Their incorporation as integral linker units in metal-organic frameworks (MOFs) can remedy these shortcomings. Moreover, the extended three-dimensional structure of MOFs gives rise to high catalyst loadings per geometric surface area. Herein, we report a new MOF that exclusively consists of cobaloximes, a widely studied HEC, that act as metallo-linkers between hexanuclear zirconium clusters. When grown on conducting substrates and under applied reductive potential, the cobaloxime linkers promote electron transport through the film as well as function as molecular HECs. The obtained turnover numbers are orders of magnitude higher than those of any other comparable cobaloxime system, and the molecular integrity of the cobaloxime catalysts is maintained for at least 18 h of electrocatalysis. Being one of the very few hydrogen evolving electrocatalytic MOFs based on a redox-active metallo-linker, this work explores uncharted terrain for greater catalyst pathways.

Place, publisher, year, edition, pages
AMER CHEMICAL SOC, 2019
National Category
Physical Chemistry
Identifiers
urn:nbn:se:uu:diva-396719 (URN)10.1021/jacs.9b07084 (DOI)000490358900028 ()31508946 (PubMedID)
Funder
EU, European Research Council, ERC-CoG2015-681895_MOFcatSwedish Research Council, 2017-04321Swedish Energy AgencyKnut and Alice Wallenberg Foundation, 2016.0072Wenner-Gren Foundations
Available from: 2019-11-08 Created: 2019-11-08 Last updated: 2019-11-08Bibliographically approved
Liu, T., Tyburski, R., Wang, S., Fernandez-Teran, R., Ott, S. & Hammarström, L. (2019). Elucidating Proton-Coupled Electron Transfer Mechanisms of Metal Hydrides with Free Energy- and Pressure-Dependent Kinetics. Journal of the American Chemical Society, 141(43), 17245-17259
Open this publication in new window or tab >>Elucidating Proton-Coupled Electron Transfer Mechanisms of Metal Hydrides with Free Energy- and Pressure-Dependent Kinetics
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2019 (English)In: Journal of the American Chemical Society, ISSN 0002-7863, E-ISSN 1520-5126, Vol. 141, no 43, p. 17245-17259Article in journal (Refereed) Published
Abstract [en]

Proton-coupled electron transfer (PCET) was studied in a series of tungsten hydride complexes with pendant pyridyl arms ([(PyCH2Cp)WH(CO)(3)], PyCH2Cp = pyridyl methyl cyclopentadienyl), triggered by laser flash-generated Ru-III-tris-bipyridine oxidants, in acetonitrile solution. The free energy dependence of the rate constant and the kinetic isotope effects (KIEs) showed that the PCET mechanism could be switched between concerted and the two stepwise PCET mechanisms (electron-first or proton-first) in a predictable fashion. Straightforward and general guidelines for how the relative rates of the different mechanisms depend on oxidant and base are presented. The rate of the concerted reaction should depend symmetrically on changes in oxidant and base strength, that is on the overall Delta G(PCET)(0), and we argue that an "asynchronous" behavior would not be consistent with a model where the electron and proton tunnel from a common transition state. The observed rate constants and KIEs were examined as a function of hydrostatic pressure (1-2000 bar) and were found to exhibit qualitatively different dependence on pressure for different PCET mechanisms. This is discussed in terms of different volume profiles of the PCET mechanisms as well as enhanced proton tunneling for the concerted mechanism. The results allowed for assignment of the main mechanism operating in the different cases, which is one of the critical questions in PCET research. They also show how the rate of a PCET reaction will be affected very differently by changes of oxidant and base strength, depending on which mechanism dominates. This is of fundamental interest as well as of practical importance for rational design of, for example, catalysts for fuel cells and solar fuel formation, which operate in steps of PCET reactions. The mechanistic richness shown by this system illustrates that the specific mechanism is not intrinsic to a specific synthetic catalyst or enzyme active site but depends on the reaction conditions.

Place, publisher, year, edition, pages
AMER CHEMICAL SOC, 2019
National Category
Physical Chemistry
Identifiers
urn:nbn:se:uu:diva-397587 (URN)10.1021/jacs.9b08189 (DOI)000493866300030 ()31587555 (PubMedID)
Funder
Swedish Research Council, 2016-04271Stiftelsen Olle Engkvist Byggmästare, 2016/3
Available from: 2019-11-25 Created: 2019-11-25 Last updated: 2019-11-25Bibliographically approved
McCarthy, B. D., Liseev, T., Beiler, A. M., Materna, K. L. & Ott, S. (2019). Facile Orientational Control of M2L2P SURMOFs on < 100 > Silicon Substrates and Growth Mechanism Insights for Defective MOFs. ACS Applied Materials and Interfaces, 11(41), 38294-38302
Open this publication in new window or tab >>Facile Orientational Control of M2L2P SURMOFs on < 100 > Silicon Substrates and Growth Mechanism Insights for Defective MOFs
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2019 (English)In: ACS Applied Materials and Interfaces, ISSN 1944-8244, E-ISSN 1944-8252, Vol. 11, no 41, p. 38294-38302Article in journal (Refereed) Published
Abstract [en]

Layer-by-layer growth of Cu-2(bdc)(2)(dabco) surface-mounted metal organic frameworks (SURMOFs) was investigated on silicon wafers treated with different surface anchoring molecules. Well-oriented growth along the [100] and [001] directions could be achieved with simple protocols: growth along the [100] direction was achieved by substrate pretreatment with 80 degrees C piranha, while growth along the [001] direction was enabled by only rinsing silicon with absolute ethanol. Growth along the [001] direction produced more homogeneous SURMOF films. Optimization to enhance [001]-preferred orientation growth revealed that small changes in the SURMOF growth sequence (the number of rinse steps and linker concentrations) have a noticeable impact on the final film quality and the number of misaligned crystals. This new straightforward protocol was used to successfully grow other layer pillar-type SURMOFs, including the growth of Cu-2(bdc)(2)(bipy) with simultaneous suppression of framework interpenetration.

Keywords
MOFs, SURMOFs, silicon, methodology, surface anchoring molecules, silatranes
National Category
Materials Chemistry
Identifiers
urn:nbn:se:uu:diva-397122 (URN)10.1021/acsami.9b12407 (DOI)000491219700097 ()31549498 (PubMedID)
Funder
EU, European Research Council, ERC-CoG2015-681895_MOFcatSwedish Energy AgencyStiftelsen Olle Engkvist Byggmästare
Available from: 2019-11-15 Created: 2019-11-15 Last updated: 2019-11-15Bibliographically approved
Queyriaux, N., Swords, W. B., Agarwata, H., Johnson, B. A., Ott, S. & Hammarström, L. (2019). Mechanistic insights on the non-innocent role of electron donors: reversible photocapture of CO2 by Ru-II-polypyridyl complexes. Dalton Transactions, 48(45), 16894-16898
Open this publication in new window or tab >>Mechanistic insights on the non-innocent role of electron donors: reversible photocapture of CO2 by Ru-II-polypyridyl complexes
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2019 (English)In: Dalton Transactions, ISSN 1477-9226, E-ISSN 1477-9234, Vol. 48, no 45, p. 16894-16898Article in journal (Refereed) Published
Abstract [en]

The ability of [Ru-II((t)Butpy)(dmbpy)(MeCN)](2+) (1-MeCN) to capture CO2, with the assistance of triethanolamine (TEOA), has been assessed under photocatalytically-relevant conditions. The photolability of 1-MeCN has proven essential to generate a series of intermediates which only differ by the nature of their monodentate ligand. In DMF, ligand photoexchange of 1-MeCN to give [Ru-II((t)Butpy)(dmbpy)(DMF)](2+) (1-DMF) proceeds smoothly with a quantum yield of 0.011. However, in the presence of TEOA, this process was disrupted, leading to the formation of a mixture of 1-DMF and [Ru-II((t)Butpy)(dmbpy)(TEOA)](+) (1-TEOA). An equilibrium constant of 3 was determined. Interestingly, 1-TEOA demonstrated an ability to reversibly catch and release CO2 making it a potentially crucial intermediate towards CO2 reduction.

Place, publisher, year, edition, pages
ROYAL SOC CHEMISTRY, 2019
National Category
Inorganic Chemistry
Identifiers
urn:nbn:se:uu:diva-400006 (URN)10.1039/c9dt03461g (DOI)000498690100006 ()31642825 (PubMedID)
Funder
Swedish Energy Agency, 11674-8Stiftelsen Olle Engkvist Byggmästare, 2016/3NordForsk
Available from: 2019-12-19 Created: 2019-12-19 Last updated: 2019-12-19Bibliographically approved
Fluch, U., McCarthy, B. D. & Ott, S. (2019). Post synthetic exchange enables orthogonal click chemistry in a metal organic framework. Dalton Transactions, 48(1), 45-49
Open this publication in new window or tab >>Post synthetic exchange enables orthogonal click chemistry in a metal organic framework
2019 (English)In: Dalton Transactions, ISSN 1477-9226, E-ISSN 1477-9234, Vol. 48, no 1, p. 45-49Article in journal (Refereed) Published
Abstract [en]

Biphenyl-4,4'-dicarboxylic acid derivatives containing either azide or acetylene functional groups were inserted into UiO-67 metal organic frameworks (MOFs) via post synthetic linker exchange. Sequential and orthogonal click reactions could be performed on these modified MOFs by incubating the crystals with small molecule substrates bearing azide or acetylene groups in the presence of a copper catalyst. H-1 NMR of digested MOF samples showed that up to 50% of the incorporated linkers could be converted to their "clicked" triazole products. Powder X-ray diffraction confirmed that the UiO-67 structure was maintained throughout all transformations. The click reaction efficiency is discussed in context of MOF crystallite size and pore size. As the incorporation of clicked linkers could be controlled by post synthetic exchange, this work introduces a powerful method of quickly introducing orthogonal modifications into known MOF architectures.

Place, publisher, year, edition, pages
ROYAL SOC CHEMISTRY, 2019
National Category
Inorganic Chemistry
Identifiers
urn:nbn:se:uu:diva-372868 (URN)10.1039/c8dt04563a (DOI)000453681400006 ()30516766 (PubMedID)
Funder
EU, European Research Council, ERC-CoG2015-681895_MOFcatSwedish Energy Agency
Available from: 2019-01-10 Created: 2019-01-10 Last updated: 2019-01-10Bibliographically approved
Pullen, S., Maji, S., Stein, M. & Ott, S. (2019). Restricted rotation of an Fe(CO)(2)(PL3)-subunit in [FeFe]-hydrogenase active site mimics by intramolecular ligation. Dalton Transactions, 48(18), 5933-5939
Open this publication in new window or tab >>Restricted rotation of an Fe(CO)(2)(PL3)-subunit in [FeFe]-hydrogenase active site mimics by intramolecular ligation
2019 (English)In: Dalton Transactions, ISSN 1477-9226, E-ISSN 1477-9234, Vol. 48, no 18, p. 5933-5939Article in journal (Refereed) Published
Abstract [en]

A new series of homodinuclear iron complexes as models of the [FeFe]-hydrogenase active site was prepared and characterized. The complexes of the general formula [Fe-2(mcbdt)(CO)(5)PPh2R] (mcbdt = benzene-1,2-dithiol-3-carboxylic acid) feature covalent tethers that link the mcbdt ligand with the phosphine ligands which are terminally coordinated to one of the Fe centres. The synthetic feasability of the concept is demonstrated with the preparation of three novel complexes. A detailed theoretical investigation showes that by introducing a rigid covalent link between the phosphine and the bridging dithiolate ligands, the rotation of the Fe(CO)(2)P unit is hindered and higher rotation barriers were calculated compared to non-linked reference complexes. The concept of restricting Fe(L)(3) rotation is an approach to kinetically stabilize terminal hydrides which are reactive intermediates in catalytic proton reduction cycles of the enzymes.

Place, publisher, year, edition, pages
ROYAL SOC CHEMISTRY, 2019
National Category
Inorganic Chemistry
Identifiers
urn:nbn:se:uu:diva-390519 (URN)10.1039/c8dt05148h (DOI)000472449300009 ()30839992 (PubMedID)
Funder
Swedish Research CouncilKnut and Alice Wallenberg FoundationSwedish Energy Agency
Available from: 2019-08-14 Created: 2019-08-14 Last updated: 2019-08-14Bibliographically approved
Das, B., Thapper, A., Ott, S. & Colbran, S. B. (2019). Structural features of molecular electrocatalysts in multi-electron redox processes for renewable energy: recent advances. SUSTAINABLE ENERGY & FUELS, 3(9), 2159-2175
Open this publication in new window or tab >>Structural features of molecular electrocatalysts in multi-electron redox processes for renewable energy: recent advances
2019 (English)In: SUSTAINABLE ENERGY & FUELS, ISSN 2398-4902, Vol. 3, no 9, p. 2159-2175Article, review/survey (Refereed) Published
Abstract [en]

Understanding the structural features of molecular electrocatalysts for carbon dioxide reduction and water oxidation is essential for manufacturing next generation catalysts for renewable energy. We will discuss the crucial structural motifs of those catalysts that have shown novel characteristics in recent years in terms of electrocatalytic efficacy (high TON, TOF and low overpotential), product selectivity and mechanisms. Both inorganic and organic homogeneous catalysts are scrutinized in this review. We will also highlight electrocatalysts with dual activity (i.e. they are able to catalyze both water oxidation and CO2 reduction) as an interesting prospect from the point of view of a single catalyst electrolyzer: a possible design for future easy-to-manufacture effective electrolyzers. This discussion will enrich the overall knowledge on the electrocatalyst design, an important step towards the development of efficient catalysts with cutting edge designs for a renewable energy future and practical applications.

National Category
Other Chemistry Topics
Identifiers
urn:nbn:se:uu:diva-393759 (URN)10.1039/c9se00280d (DOI)000482057500001 ()
Funder
Australian Research Council, DP 160104383
Available from: 2019-09-27 Created: 2019-09-27 Last updated: 2019-09-27Bibliographically approved
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Identifiers
ORCID iD: ORCID iD iconorcid.org/0000-0002-1691-729X

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