TY  - JOUR
A1  - Schlossarek, Tim
A1  - Stepanenko, Vladimir
A1  - Beuerle, Florian
A1  - Würthner, Frank
T1  - Self‐assembled Ru(bda) Coordination Oligomers as Efficient Catalysts for Visible Light‐Driven Water Oxidation in Pure Water
JF  - Angewandte Chemie International Edition
N2  - Water‐soluble multinuclear complexes based on ruthenium 2,2′‐bipyridine‐6,6′‐dicarboxylate (bda) and ditopic bipyridine linker units are investigated in three‐component visible light‐driven water oxidation catalysis. Systematic studies revealed a strong enhancement of the catalytic efficiency in the absence of organic co‐solvents and with increasing oligomer length. In‐depth kinetic and morphological investigations suggest that the enhanced performance is induced by the self‐assembly of linear Ru(bda) oligomers into aggregated superstructures. The obtained turnover frequencies (up to 14.9 s\(^{−1}\)) and turnover numbers (more than 1000) per ruthenium center are the highest reported so far for Ru(bda)‐based photocatalytic water oxidation systems.
KW  - artificial photosynthesis
KW  - coordination oligomer
KW  - photocatalysis
KW  - Ruthenium complexes
KW  - water oxidation
Y1  - 2022
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-312184
VL  - 61
IS  - 52
ER  - 
TY  - JOUR
A1  - Karak, Suvendu
A1  - Stepanenko, Vladimir
A1  - Addicoat, Matthew A.
A1  - Keßler, Philipp
A1  - Moser, Simon
A1  - Beuerle, Florian
A1  - Würthner, Frank
T1  - A Covalent Organic Framework for Cooperative Water Oxidation
JF  - Journal of the American Chemical Society
N2  - The future of water-derived hydrogen as the “sustainable energy source” straightaway bets on the success of the sluggish oxygen-generating half-reaction. The endeavor to emulate the natural photosystem II for efficient water oxidation has been extended across the spectrum of organic and inorganic combinations. However, the achievement has so far been restricted to homogeneous catalysts rather than their pristine heterogeneous forms. The poor structural understanding and control over the mechanistic pathway often impede the overall development. Herein, we have synthesized a highly crystalline covalent organic framework (COF) for chemical and photochemical water oxidation. The interpenetrated structure assures the catalyst stability, as the catalyst’s performance remains unaltered after several cycles. This COF exhibits the highest ever accomplished catalytic activity for such an organometallic crystalline solid-state material where the rate of oxygen evolution is as high as ∼26,000 μmol L\(^{–1}\) s\(^{–1}\) (second-order rate constant k ≈ 1650 μmol L s\(^{–1}\) g\(^{–2}\)). The catalyst also proves its exceptional activity (k ≈ 1600 μmol L s\(^{–1}\) g\(^{–2}\)) during light-driven water oxidation under very dilute conditions. The cooperative interaction between metal centers in the crystalline network offers 20–30-fold superior activity during chemical as well as photocatalytic water oxidation as compared to its amorphous polymeric counterpart.
KW  - water oxidation
KW  - sustainable energy source
KW  - covalent organic framework
KW  - catalyst
KW  - crystalline
KW  - catalysis
KW  - nanoparticles
Y1  - 2022
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-287591
UR  - https://pubs.acs.org/doi/10.1021/jacs.2c07282
SN  - 0002-7863
VL  - 144
IS  - 38
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  -