Influence of the spatial distribution of copper sites on the selectivity of the oxygen reduction reaction.

Moving towards a hydrogen economy raises the demand for affordable and efficient catalysts for the oxygen reduction reaction. Cu-bmpa (bmpa = bis(2-picolyl)amine) is shown to have moderate activity, but poor selectivity for the 4-electron reduction of oxygen to water. To enhance the selectivity towards water formation, the cooperative effect of three Cu-bmpa binding sites in a single trinuclear complex is investigated.

Pinpointing the active species of the Cu(DAT) catalyzed oxygen reduction reaction.

Dinuclear CuII complexes bearing two 3,5-diamino-1,2,4-triazole (DAT) ligands have gained considerable attention as a potential model system for laccase due to their low overpotential for the oxygen reduction reaction (ORR). In this study, the active species for the ORR was investigated. The water soluble dinuclear copper complex (Cu(DAT)) was obtained by mixing a 1 : 1 ratio of Cu(OTf)2 and DAT in water.

In operando studies on the electrochemical oxidation of water mediated by molecular catalysts.

Homogeneous reactions in general are relatively easy to study with respect to heterogeneous systems since all catalytic sites are uniform and can be addressed simultaneously. The latter feature is fully out of the window in an electrochemical context, where only the few catalytic species that are sufficiently close to the electrode undergo redox reactions. Especially in the water oxidation reaction where harsh reaction conditions are employed, a clear picture of what is the active species, what products are formed, how one can steer this, and how it all depends on the exact reaction conditions is important to be able to fully unravel the key reaction paths.

Early stages of catalyst aging in the iridium mediated water oxidation reaction.

When exposed to a potential exceeding 1.5 V versus RHE for several minutes the molecular iridium bishydroxide complex bearing a pentamethylcyclopentadienyl and a N-dimethylimidazolin-2-ylidene ligand spontaneously adsorbs onto the surface of glassy carbon and gold electrodes. Simultaneously with the adsorption of the material on the electrode, the evolution of dioxygen is detected and modifications of the catalyst structure are observed.

Evaluation of iron-based electrocatalysts for water oxidation - an on-line mass spectrometry approach.

Using on-line mass spectrometry in combination with classical electroanalytical techniques makes it possible to reliably determine onset potentials and to distinguish between competing reactions such as oxygen evolution and carbon dioxide formation. Using these on-line MS methods, catalytic water oxidation activity was demonstrated for cis-[Fe(cyclam)Cl2]Cl (1) and [Fe(cyclamacetate)Cl] (2).

Challenges in reduction of dinitrogen by proton and electron transfer.

Ammonia is an important nutrient for the growth of plants. In industry, ammonia is produced by the energy expensive Haber-Bosch process where dihydrogen and dinitrogen form ammonia at a very high pressure and temperature. In principle one could also reduce dinitrogen upon addition of protons and electrons similar to the mechanism of ammonia production by nitrogenases.