| 1. |
- Dürr, Robin N., et al.
(author)
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Robust and Efficient Screen-Printed Molecular Anodes with Anchored Water Oxidation Catalysts
- 2021
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In: ACS Applied Energy Materials. - : American Chemical Society (ACS). - 2574-0962. ; 4:10, s. 10534-10541
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Journal article (peer-reviewed)abstract
- In this work, we present the preparation and performance of screen-printed anodes for electrochemical water splitting in neutral media. With the combination of printed electrodes and molecular water oxidation catalysts, we successfully take advantage of a low-cost and up-scalable fabrication method of graphitic electrodes with the outstanding catalytic activity and stability of oligomeric ruthenium-based molecular water oxidation catalysts, offering a promising electroanode for water oxidation applications.
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| 2. |
- Grammatico, Domenico, et al.
(author)
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Heterogenised Molecular Catalysts for Sustainable Electrochemical CO 2 Reduction
- 2022
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In: Angewandte Chemie International Edition. - : John Wiley & Sons. - 1433-7851 .- 1521-3773. ; 61:38
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Research review (peer-reviewed)abstract
- There has been a rapid rise in interest regarding the advantages of support materials to protect and immobilise molecular catalysts for the carbon dioxide reduction reaction (CO2RR) in order to overcome the weaknesses of many well-known catalysts in terms of their stability and selectivity. In this Review, the state of the art of different catalyst-support systems for the CO2RR is discussed with the intention of leading towards standard benchmarking for comparison of such systems across the most relevant supports and immobilisation strategies, taking into account these multiple pertinent metrics, and also enabling clearer consideration of the necessary steps for further progress. The most promising support systems are described, along with a final note on the need for developing more advanced experimental and computational techniques to aid the rational design principles that are prerequisite to prospective industrial upscaling.
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| 3. |
- Howe, Andrew, 1995-, et al.
(author)
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Carbanion Ruthenium Complexes for Water Oxidation
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Other publication (other academic/artistic)abstract
- A novel carbanion complex, [RuIII(dpa)(4,4’-bypridine)2], (dpa = ((5-methyl-1,3-phenylene)bis(pyridine-6,2-diyl))bis(hydroxy(l1-oxidaneyl)phosphine oxide),), has been prepared, characterised and incorporated as a coordination oligomer to form II@MWCNT@GC. Once incorporated in a coordination oligomer, this otherwise inert and stable diphosphonate complex has the ability to engage in electrocatalysis, with Faradaic efficiency (FE) of up to 85%. Scanning electron microscopy (SEM), energy-dispersive X-ray (EDX) spectroscopy and XPS was used to confirm anchoring onto the graphitic surface.
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| 4. |
- Zamader, Afridi, et al.
(author)
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Electrode Integration of Synthetic Hydrogenase as Bioinspired and Noble Metal-Free Cathodes for Hydrogen Evolution
- 2023
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In: ACS Catalysis. - : American Chemical Society (ACS). - 2155-5435. ; 13:2, s. 1246-1256
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Journal article (peer-reviewed)abstract
- Diiron complexes mimicking the H-cluster of [FeFe]-hydrogenases have been extensively studied as (electro-)catalysts for proton reduction under homogeneous conditions. The incorporation of such complexes as "active sites" within macromolecular scaffolds such as organic polymers is receiving increasing attention as this strategy allows controlling the environment, that is, the outer coordination sphere, around the molecular catalytic center, to tune its performance as well as its stability. Here, we report on the synthesis and characterization of a library of metallo-copolymers featuring a bioinspired diiron active site and internal proton relays based on a previous report [Brezinski et al. Angew. Chem. Int. Ed. 2018, 57, 11898-11902]. The polymers are further functionalized with various amounts of pyrene groups for efficient noncovalent anchoring onto multi-walled carbon nanotubes (MWNTs), enabling the preparation of molecularly engineered electrode materials. The addition of pyrene anchors resulted in improved activity and stability, with a pyrene loading of about similar to 8% corresponding to an optimized balance between polymer hydrophilicity and surface affinity. The best material displayed an average turnover frequency (TOFH2) of 4.3 +/- 0.6 s(-1) and a conservative turnover number for H-2 production (TONH2) of 3.1 +/- 0.4 x 10(5) after 20 h of continuous bulk electrolysis in aqueous conditions at 0.39 V overpotential. Interestingly, comparing such activities with an analogous diiron site deprived from polymeric scaffold revealed that latter could only show TONH2 of similar to 4 +/- 2 x 10(3) and TOFH2 of 0.06 +/- 0.02 s(-1) in 20 h under the same conditions. Post operando analysis of the modified electrodes suggests that electrode inactivation occurs via leaching of the diiron core from MWNT. In addition, a life cycle assessment was carried out to evaluate the performance of the engineered electrode materials not only from a technical perspective but also from an environmental point of view.
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| 5. |
- Zamader, Afridi, et al.
(author)
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Non‐Covalent Integration of a [FeFe]‐Hydrogenase Mimic to Multiwalled Carbon Nanotubes for Electrocatalytic Hydrogen Evolution
- 2022
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In: Chemistry - A European Journal. - : Wiley-Blackwell. - 0947-6539 .- 1521-3765. ; 28:69
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Journal article (peer-reviewed)abstract
- Surface integration of molecular catalysts inspired from the active sites of hydrogenase enzymes represents a promising route towards developing noble metal-free and sustainable technologies for H2 production. Efficient and stable catalyst anchoring is a key aspect to enable this approach. Herein, we report the preparation and electrochemical characterization of an original diironhexacarbonyl complex including two pyrene groups per catalytic unit in order to allow for its smooth integration, through π-interactions, onto multiwalled carbon nanotube-based electrodes. In this configuration, the grafted catalyst could reach turnover numbers for H2 production (TONH2) of up to 4±2×103 within 20 h of bulk electrolysis, operating at neutral pH. Post operando analysis of catalyst functionalized electrodes revealed the degradation of the catalytic unit occurred via loss of the iron carbonyl units, while the anchoring groups and most part of the ligand remained attached onto multiwalled carbon nanotubes.
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| 6. |
- Zamader, Afridi, et al.
(author)
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Synthetic styrene-based bioinspired model of the [FeFe]-hydrogenase active site for electrocatalytic hydrogen evolution
- 2023
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In: Sustainable Energy & Fuels. - : Royal Society of Chemistry. - 2398-4902. ; 7:19, s. 4967-4976
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Journal article (peer-reviewed)abstract
- Integration of molecular catalysts inside polymeric scaffolds has gained substantial attention over the past decade, as it provides a path towards generating systems with enhanced stability as well as enzyme-like morphologies and properties. In the context of solar fuels research and chemical energy conversion, this approach has been found to improve both rates and energy efficiencies of a range of catalytic reactions. However, system performance still needs to be improved to reach technologically relevant currents and stability, parameters that are heavily influenced by the nature of the incorporated molecular catalyst. Here, we have focused on the integration of a biomimetic {Fe2(μ-adt)(CO)6} (–CH2NHCH2S–, azadithiolate or adt2−) based active site (“[2Fe2S]adt”), inspired by the catalytic cofactor of [FeFe] hydrogenases, within a synthetic polymeric scaffold using free radical polymerization. The resulting metallopolymers [2Fe2S]adtk[DMAEMA]l[PyBMA]m (DMAEMA = dimethylaminoethyl methacrylate as water soluble monomer; PyBMA = 4-(pyren-1-yl)-butyl methacrylate as hydrophobic anchor for heterogenization) were found to be active for electrochemical H2 production in neutral aqueous media. The pyrene content was varied to optimize durability and activity. Following immobilization on multiwalled carbon nanotubes (MWNT) the most active metallopolymer, containing ∼2.3 mol% of PyBMA, could reach a turnover number for hydrogen production (TONH2) of ∼0.4 ×105 over 20 hours of electrolysis at an overpotential of 0.49 V, two orders of magnitude higher than the isolated catalyst counterpart. The study provides a synthetic methodology for incorporating catalytic units featuring second coordination sphere functional groups, and highlights the benefit of the confinement within the polymer matrix for catalytic performance.
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