Oratie uitgesproken door Prof. dr. Ineke van der Ham bij de aanvaarding van het ambt van hoogleraar met als leeropdracht Technologische vernieuwingen in de neuropsychologie aan de Universiteit... Show moreOratie uitgesproken door Prof. dr. Ineke van der Ham bij de aanvaarding van het ambt van hoogleraar met als leeropdracht Technologische vernieuwingen in de neuropsychologie aan de Universiteit Leiden op vrijdag 1 december 2023 Show less
Inaugural lecture delivered by Prof. Dr. Ineke van der Ham upon acceptance of the position of professor with the chair Technological innovations in neuropsychology at Leiden University on Friday,... Show moreInaugural lecture delivered by Prof. Dr. Ineke van der Ham upon acceptance of the position of professor with the chair Technological innovations in neuropsychology at Leiden University on Friday, December 1, 2023 Show less
Upon the electrochemical reduction of an in situ generated 5-diazo-1,10-phenanthroline ion, phenanthroline was covalently attached to a gold electrode. The grafted molecules act as a ligand when... Show moreUpon the electrochemical reduction of an in situ generated 5-diazo-1,10-phenanthroline ion, phenanthroline was covalently attached to a gold electrode. The grafted molecules act as a ligand when brought in contact with a copper-containing electrolyte solution. As the ligands are limited in spatial movement, the exclusive formation of the active species with only one phenanthroline ligand coordinated was expected. The in situ generated complexes have been investigated for activity in the oxygen reduction reaction, for which an overpotential of 800 mV is observed. During catalysis, initially a thick copper layer is formed on top of an organic layer that is still present on the gold surface. Upon deterioration of the organic layer underneath the copper over time, the amount of copper on the electrode and thereby the electrocatalytic activity decreases. Show less
Mulder, H.; Oudgenoeg-Paz, O.; Verhagen, J.; Ham, C.J.M. van der; Stigchel, S. van der 2022
Based on previous work that identified iridium(III) Cp* complexes containing a C,N-bidentate chelating triazolylidene-pyridyl ligand (Cp* = pentamethylcyclopentadienyl, C5Me5-) as efficient... Show moreBased on previous work that identified iridium(III) Cp* complexes containing a C,N-bidentate chelating triazolylidene-pyridyl ligand (Cp* = pentamethylcyclopentadienyl, C5Me5-) as efficient molecular water oxidation catalysts, a series of new complexes based on this motif has been designed and synthesized in order to improve catalytic activity. Modifications include specifically the introduction of electron-donating substituents into the pyridyl unit of the chelating ligand (H, a; 5-OMe, b; 4-OMe, c; 4-tBu, d; 4-NMe2, e), as well as electronically active substituents on the triazolylidene C4 position (H, 8; COOEt, 9; OEt, 10; OH, 11; COOH, 12). Chemical oxidation using cerium ammonium nitrate (CAN) indicates a clear structure-activity relationship with electron-donating groups enhancing catalytic turnover frequency, especially when the donor substituent is positioned on the triazolylidene ligand fragment (TOFmax = 2500 h(-)(1) for complex 10 with a MeO group on pyr and a OEt-substituted triazolylidene, compared to 700 h(-)(1) for the parent benchmark complex without substituents). Electrochemical water oxidation does not follow the same trend, and reveals that complex 8b without a substituent on the triazolylidene fragment outperforms complex 10 by a factor of 5, while in CAN-mediated chemical water oxidation, complex 10 is twice more active than 8b. This discrepancy in catalytic activity is remarkable and indicates that caution is needed when benchmarking iridium water oxidation catalysts with chemical oxidants, especially when considering that application in a potential device will most likely involve electrocatalytic water oxidation. Show less
Before the large scale use of renewable energy sources can be implemented in our society, the storage of electrical energy needs to be tackled. Storage the energy as hydrogen via the reduction of... Show moreBefore the large scale use of renewable energy sources can be implemented in our society, the storage of electrical energy needs to be tackled. Storage the energy as hydrogen via the reduction of protons is a good option. In order to form a closed electrochemical cycle an oxidation reaction need to be used. The water oxidation reaction is a good candidate as second reaction. When the energy is released, the oxygen reduction reaction is used to reduce the oxygen produced in the water oxidation reaction. This thesis focusses on heterogenized water oxidation and oxygen reduction catalysts. Water oxidation occurs under highly oxidizing potentials. This causes many molecular catalysts to degrade. In this thesis an example is given of two pyridyl-triazolylidene iridium precatalysts which have different rates of activation and deposition formation under reactive conditions. A copper-based catalyst has two different activation processes, an oxidative and a reductive pathway, which stress the importance of choosing the right reaction conditions before the start of catalysis. A copper complex with 1,10-phenanthroline ligands only forms an active oxygen reduction catalyst when one 1,10-phenanthroline ligand is coordinated to the copper ion. By immobilizing the 1,10-phenanthroline ligand on the electrode, an active heterogenized catalyst is formed. Show less
Ham, C.J.M. van der; Isik, F.; Verhoeven, T.W.G.M.; Niemantsverdriet, J.W.; Hetterscheid, D.G.H. 2017
