| 1. |
- Howe, Andrew, 1995-, et al.
(författare)
-
Carbanion Ruthenium Complexes for Water Oxidation
-
Annan publikation (övrigt vetenskapligt/konstnärligt)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.
|
|
| 2. |
- Howe, Andrew, 1995-
(författare)
-
Immobilisation of Ru-Based Molecular Catalysts for Electrochemical Water Oxidation
- 2022
-
Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Artificial photosynthesis requires catalysts for efficient and selective conversions of small molecules. Molecular catalysts are advantageous to use in these instances as they offer precise control over chemical reactivity. They are synthetically tuneable, and their catalytic mechanisms are often well documented and more readily understood than those of solid-state catalysts. In this thesis, the synthetic incorporation of molecular catalysts into heterogenised molecular anodes for water oxidation are evaluated. The catalysts are incorporated as structural linkers into porous metal-organic framework (MOF) structures, and as coordination oligomers stacked onto graphitic surfaces. The preparation of MOF/molecular catalyst hybrid materials of two topologies, UiO (UiO = Universitet i Oslo) and NU-1000 (NU = Northwestern University), were investigated. Multiple synthetic methods for the incorporation of molecular ruthenium-based catalysts into MOFs were examined in papers I and II. In paper III of this thesis, a Ru-bda type molecular complex was successfully used in the solvothermal synthesis of a new MOF. The resulting material is the first of its kind that is built exclusively from molecular water oxidation catalyst linkers. It is shown that MOF incorporation greatly enhances the structural stability of the catalyst linker in chemical water oxidation experiments, giving rise to higher turnover numbers compared to that of a homogenous reference system. Finally, paper IV describes a stable and inert molecular ruthenium complex, which possesses a flexible adaptative multidentate equatorial (FAME) type equatorial ligand with a carbanion on the equatorial ligand that forms a C-Ru bond. This molecular complex is studied in homogeneous phase, and subsequently incorporated into a coordination oligomer, which can be activated for water oxidation catalysis. This finding broadens the field of molecular catalysis significantly, and proves that supramolecular interactions can be used to promote electrocatalysis in complexes which are otherwise too inert and stable to engage in electrocatalytic reactions.
|
|
| 3. |
- Howe, Andrew, 1995-, et al.
(författare)
-
Synthesis of a Metal-Organic Framework Made Entirely of the Molecular Ruthenium Water Oxidation Complex
-
Annan publikation (övrigt vetenskapligt/konstnärligt)abstract
- A new type of metal-organic framework (MOF) is described, with the linker moeities made entirely from Ru water oxidation catalyst with the formula [(RuII(bda)(py(PhCOOH)2)], 1, (bda = [2,2′-bipyridine]-6,6′-dicarboxylate and; py(PhCOOH)2 = (4,4'-(pyridine-3,5-diyl)dibenzoic acid), that is based on the Ru-bda family of water oxidation catalysts has been prepared and characterised. Due to its fixed equatorial ligand, with no features that can negatively influence the solvothermal synthesis, A MOF was preapred using 1 as the sole linker, producing a Zr-based framework, 2, that can be prepared in bulk or on a thin-film and characterised. The MOF formation was confirmed by powder X-ray diffraction (PXRD) and scanning electron microscopy (SEM), and Ru linker incorporation was shown by energy-dispersive X-ray (EDX) spectroscopies, X-ray photoelectron spectroscopy (XPS) and inductively coupled plasma optical emission spectroscopy (ICP-OES) analyses. Clear redox couples associated with 1 can be observed upon electrochemical characterisation using cyclic voltammetry (CV) and differential pulse voltammetry (DPV). This provides an interesting study of the electrochemical behaviour of a molecular water oxidation catalysts when it is an integral, structural component of a framework, which has found certain supramolecular, non-covalent, anionic and steric conditions need to be met in order to obtain effective catalysis when using Ru-bda type of catalyst.
|
|
