Up to now, platinum and its alloys are dominantly used as catalysts for the electro-reduction of oxygen because of its high chemical stability and activity in acidic media. Development of cost-saving alternatives has to face the requirement that the new materials have to be oxidatively stable in acids.

The lecture introduces two promising material systems, based on molecular cobalt – iron – nitrogen centres integrated in a graphite matrix as well as stabilized ruthenium particles.

Catalytically active cobalt and iron centres can be protected from oxidation by anchorage of the metal ions in a chelate-type structure. In the case of ruthenium a decoration of the surfaces of the nanoparticles using chalcogen such as sulphur or selenium leads to a stabilisation and a significant enhancement of reactivity.

Furthermore, In contrast to carbon-supported platinum catalysts where nano-sized particles coalesce after short operation time under fuel cell conditions, surface stabilized ruthenium particles remain separated.

In the talk, the following topics will be addressed:

- preparation strategies and synthesis of non-platinum electrocatalysts;

- elucidation of structure and of electronic state of the catalysts using

a) synchrotron radiation (in-situ X-ray Absorption Fine Structure XAFS and Anomalous Small Angle X-ray Scattering ASAXS analyses),

b) Mößbauer spectroscopy and c) Electron Paramagnetic Resonance EPR;

- structure–activity relationship combining electrochemical and structural findings.

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1. Activation of Methanol-Tolerant Carbon-Supported RuSe_x Electrocatalytic Nanoparticles Towards More Efficient Oxygen Reduction