TY  - JOUR
A1  - Schindler, Dorothee
A1  - Meza-Chincha, Anna-Lucia
A1  - Roth, Maximilian
A1  - Würthner, Frank
T1  - Structure-Activity Relationship for Di- up to Tetranuclear Macrocyclic Ruthenium Catalysts in Homogeneous Water Oxidation
JF  - Chemistry—A European Journal
N2  - Two di- and tetranuclear Ru(bda) (bda: 2,2′-bipyridine-6,6′-dicarboxylate) macrocyclic complexes were synthesized and their catalytic activities in chemical and photochemical water oxidation investigated in a comparative manner to our previously reported trinuclear congener. Our studies have shown that the catalytic activities of this homologous series of multinuclear Ru(bda) macrocycles in homogeneous water oxidation are dependent on their size, exhibiting highest efficiencies for the largest tetranuclear catalyst. The turnover frequencies (TOFs) have increased from di- to tetranuclear macrocycles not only per catalyst molecule but more importantly also per Ru unit with TOF of 6 \(^{-1}\) to 8.7 \(^{-1}\) and 10.5 s\(^{-1}\) in chemical and 0.6 s\(^{-1}\) to 3.3 \(^{-1}\) and 5.8 \(^{-1}\) in photochemical water oxidation per Ru unit, respectively. Thus, for the first time, a clear structure–activity relationship could be established for this novel class of macrocyclic water oxidation catalysts.
KW  - homogeneous catalysis
KW  - water oxidation
KW  - ruthenium catalysts
KW  - renewable fuels
KW  - metallomacrocycles
Y1  - 2021
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-256792
VL  - 27
IS  - 68
ER  - 
TY  - JOUR
A1  - Schindler, Dorothee
A1  - Gil‐Sepulcre, Marcos
A1  - Lindner, Joachim O.
A1  - Stepanenko, Vladimir
A1  - Moonshiram, Dooshaye
A1  - Llobet, Antoni
A1  - Würthner, Frank
T1  - Efficient Electrochemical Water Oxidation by a Trinuclear Ru(bda) Macrocycle Immobilized on Multi‐Walled Carbon Nanotube Electrodes
JF  - Advanced Energy Materials
N2  - Catalytic water splitting is a viable process for the generation of renewable fuels. Here it is reported for the first time that a trinuclear supramolecular Ru(bda) (bda: 2,2′‐bipyridine‐6,6′‐dicarboxylate) catalyst, anchored on multi‐walled carbon nanotubes and subsequently immobilized on glassy carbon electrodes, shows outstanding performance in heterogeneous water oxidation. Activation of the catalyst on anodes by repetitive cyclic voltammetry (CV) scans results in a catalytic current density of 186 mA cm\(^{−2}\) at a potential of 1.45 V versus NHE. The activated catalyst performs water oxidation at an onset overpotential of 330 mV. The remarkably high stability of the hybrid anode is demonstrated by X‐ray absorption spectroscopy and electrochemically, revealing the absence of any degradation after 1.8 million turnovers. Foot of the wave analysis of CV data of activated electrodes with different concentrations of catalyst indicates a monomolecular water nucleophilic attack mechanism with an apparent rate constant of TOFmax (turnover frequency) of 3200 s\(^{−1}\).
KW  - electrocatalysis
KW  - heterogeneous catalysis
KW  - renewable fuels
KW  - ruthenium bda complexes
KW  - water splitting
Y1  - 2020
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-218381
VL  - 10
IS  - 43
ER  -