06 mars 2010

Energetic profile of the reduction reaction of protons to yield hydrogen.

Using hydrogen as a power resource requires transforming it into electricity, and vice-versa. These reactions are usually catalyzed by platinum, a noble and rare metal. The iRTSV, associated with Liten and Iramis, has proposed compounds based on nickel as an alternative. Thanks to ab initio calculations, we have demonstrated that the catalytic activity of these compounds could be greatly improved by slightly changing their structure.


For several years CEA/DSV has developed molecules based on non-noble metals, with bio-inspired molecules structured from enzymes. Some of these molecules have shown a catalytic activity towards hydrogen production and its dissociation in a fuel cell. Based on theoretical chemistry ab initio methods, we have developed with Liten a multi-scale model to understand the electrochemical mechanisms at stake with these Ni-containing bio-inspired molecules. For the first time, full reaction mechanisms have been identified. From this understanding, suggestions for structural modifications have been made in order to increase the yield of theses systems and their stability.


From the thermodynamic parameters thus obtained, a chemically kinetic model of these reactions has been developed and integrated into a calculation code, used for the simulation of a completely operational fuel cell. The results obtained are in very good quantitative agreement with experiments performed on real cells by Liten and iRTSV. The simulation also predicts that a pollutant such as CO has less impact on the efficiency of these new molecules than on pure platinum.


Further reading: A. Kachmar et al., J. Phys. Chem. A 114 (2010) 11861


Maj : 17/02/2014 (944)


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