Lele Duan

Isolated Seven-Coordinate Ru(IV) Dimer Complex with [HOHOH]− Bridging Ligand as an Intermediate for Catalytic Water Oxidation

With the inspiration from an oxygen evolving complex (OEC) in Photosystem II (PSII), a mononuclear Ru(II) complex with a tetradentate ligand containing two carboxylate groups has been synthesized and structurally characterized. This Ru(II) complex showed efficient catalytic properties toward water oxidation by the chemical oxidant cerium(IV) ammonium nitrate. During the process of catalytic water oxidation, Ru(III) and Ru(IV) species have been successfully isolated as intermediates. To our surprise, X-ray crystallography together with HR-MS revealed that the Ru(IV) species is a seven-coordinate Ru(IV) dimer complex containing a [HOHOH](-) bridging ligand. This bridging ligand has a short O...O distance and is hydrogen bonded to two water molecules. The discovery of this very uncommon seven-coordinate Ru(IV) dimer together with a hydrogen bonding network may contribute to a deeper understanding of the mechanism for catalytic water oxidation. It will also provide new possibilities for the design of more efficient catalysts for water oxidation, which is the key step for solar energy conversion into hydrogen by light-driven water splitting, the ultimate challenge in artificial photosynthesis.

A photoelectrochemical device for visible light driven water splitting by a molecular ruthenium catalyst assembled on dye-sensitized nanostructured TiO2

A photoelectrochemical device with a molecular Ru catalyst assembled via pH-modified Nafion on a dye-sensitized nanostructured TiO(2) film as anode and a Pt foil as cathode has been successfully demonstrated to split water into O(2) and H(2) driven by visible light.

Chemical and Light‐Driven Oxidation of Water Catalyzed by an Efficient Dinuclear Ruthenium Complex

Chemical and light-driven oxidation of water catalyzed by an efficient dinuclear ruthenium complex

Visible light driven hydrogen production from a photo-active cathode based on a molecular catalyst and organic dye-sensitized p-type nanostructured NiO

A molecular device with a photocathode for hydrogen generation has been successfully demonstrated, based on an earth abundant and inexpensive p-type semiconductor NiO, an organic dye P1 and a cobalt catalyst Co1.

Structural Modifications of Mononuclear Ruthenium Complexes: A Combined Experimental and Theoretical Study on the Kinetics of Ruthenium‐Catalyzed Water Oxidation

Structural Modifications of Mononuclear Ruthenium Complexes : A Combined Experimental and Theoretical Study on the Kinetics of Ruthenium-Catalyzed Water Oxidation

Highly efficient and robust molecular ruthenium catalysts for water oxidation

Water oxidation catalysts are essential components of light-driven water splitting systems, which could convert water to H2 driven by solar radiation (H2O + hν → 1/2O2 + H2). The oxidation of water (H2O → 1/2O2 + 2H+ + 2e-) provides protons and electrons for the production of dihydrogen (2H+ + 2e- → H2), a clean-burning and high-capacity energy carrier. One of the obstacles now is the lack of effective and robust water oxidation catalysts. Aiming at developing robust molecular Ru-bda (H2bda = 2,2′-bipyridine-6,6′-dicarboxylic acid) water oxidation catalysts, we carried out density functional theory studies, correlated the robustness of catalysts against hydration with the highest occupied molecular orbital levels of a set of ligands, and successfully directed the synthesis of robust Ru-bda water oxidation catalysts. A series of mononuclear ruthenium complexes [Ru(bda)L2] (L = pyridazine, pyrimidine, and phthalazine) were subsequently synthesized and shown to effectively catalyze CeIV-driven [CeIV = Ce(NH4)2(NO3)6] water oxidation with high oxygen production rates up to 286 s-1 and high turnover numbers up to 55,400.

A New Dinuclear Ruthenium Complex as an Efficient Water Oxidation Catalyst

A dinuclear ruthenium complex, which acts as a molecular catalyst for water oxidation, has been synthesized and characterized. The electronic and electrochemical properties were studied by UV-vis spectroscopy and cyclic voltammetry. The oxidation potentials of the complex are significantly lowered by introducing a negatively charged carboxylate ligand, in comparison with those of the reported complexes that have neutral ligands. The catalytic activity of the complex toward water oxidation using Ce(NH(4))(2)(NO(3))(6) as a chemical oxidant was investigated by means of an oxygen electrode and mass spectrometry. The turnover number of this catalyst with Ce(IV) as the chemical oxidant was found to be ca. 1700. The mass spectroscopic analysis of the isotopomer distribution in oxygen evolved from (18)O-labeled water indicates that O atoms in the evolved oxygen originate from water.

Evolution of O2 in a Seven-Coordinate RuIV Dimer Complex with a [HOHOH]- Bridge: A Computational Study

Evolution of O-2 in a Seven-Coordinate Ru-IV Dimer Complex with a [HOHOH] (-) Bridge : A Computational Study

Visible light-driven water oxidation catalyzed by a highly efficient dinuclear ruthenium complex

Visible light-driven water oxidation has been achieved by the dinuclear ruthenium complex 1 with a high turnover number of 1270 in a homogeneous system in the presence of a Ru polypyridine complex photosensitizer.

Ru complexes containing pyridine dicarboxylate ligands: electronic effects on their catalytic activity toward water oxidation

Two series of mononuclear ruthenium complexes [Ru(pdc)L3] (H2pdc = 2,6-pyridinedicarboxylic acid; L = 4-methoxypyridine, 1; pyridine, 2; pyrazine, 3) and [Ru(pdc)L2(dmso)] (dmso = dimethyl sulfoxide; L = 4-methoxypyridine, 4; pyridine, 5) were synthesized and spectroscopically characterized. Their catalytic activity toward water oxidation has been examined using Ce(IV) (Ce(NH4)2(NO3)6) as the chemical oxidant under acidic conditions. Complexes 1, 2 and 3 are capable of catalyzing Ce(IV)-driven water oxidation while 4 and 5 are not active. Electronic effects on their catalytic activity were illustrated: electron donating groups increase the catalytic activity.