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O: Fachverband Oberflächenphysik

O 75: Particles and clusters

O 75.7: Vortrag

Donnerstag, 29. März 2012, 17:30–17:45, MA 041

How do metal clusters split water?
Towards a theoretical understanding of co-catalysts for water oxidation — •Harald Oberhofer and Karsten Reuter — TU Munich, Garching, Germany

Efficient, sustainable production of molecular hydrogen—a promising alternative to batteries in terms of energy storage—is still an unsolved problem. Implementation of direct water splitting using only sunlight and suitable photo-catalysts so far has been hampered by poor photon absorption properties of the materials and low reaction efficiencies. One ansatz of overcoming the latter obstacle is the use of small metal clusters as co-catalysts, a method that yielded promising results in experiments. Yet, the actual effect of co-catalysts on the reaction is poorly understood. In our contribution we discuss our DFT-based efforts towards a microscopic understanding of small metal clusters as co-catalysts. We present our studies, based on a thermodynamic approach pioneered by Nørskov and Rossmeisl [J. Phys. Chem. B 108, 17886 (2004)], of the water oxidation reaction on various metal clusters in the non-scalable size regime (less than 20 atoms) and compare with the extended surface. On top of these results we discuss the influence of solvent on the reaction as well as the stabilisation of electron holes necessary for the reaction. Conclusions of the presented work will in the future be used to postulate micro-kinetic reaction pathways and determine reaction rates comparable with experiment.