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Description:
Our energy system and the energy market have changed radically with the use of energies from the renewable sources solar and wind due to their highly fluctuating power generation. The share of renewable energies in the energy mix can therefore only be further increased, if economically viable solutions for the storage of energy are considered. In the concept of the hydrogen economy, hydrogen will be used as the main energy carrier. The sustainable production of hydrogen achieved by the electrochemical splitting of water into hydrogen and oxygen and their later utilization in fuel cells include the exchange of electrons on an electrode. Due to the fast kinetics of the hydrogen related reactions, the catalysis of the electrochemical oxygen reactions become the actual bottleneck, namely the oxygen evolution reaction—OER (water electrolysis) and the oxygen reduction reaction—ORR (fuel cells). By enlarging the electrochemically usable electrode surface area, the efficiency of these reactions can be increased. In the present thesis, ultrashort laser pulses (shorter than a few picoseconds) were used to generate various surface-rich structures on metal electrodes. For this purpose, the first systematic study of the surface area enlargement of platinum electrodes using the laser-induced surface structures LIPSS, CLP and black metal was examined. Especially, the black metal surface structure exhibited an exceptionally high surface area increase of 1500 times compared to a polished platinum surface. Subsequently, the black metal surface structure was transferred to less expensive electrode materials, especially to nickel. In order to prevent oxidation of the material during the process and therefore to ensure good electrical conductivity of the electrode, the laser structuring was carried out in argon atmosphere. During the investigations, a new highly porous surface structure was discovered and it was called laser-induced nano-foam (LINF). Therefore, a nickel electrode was scanned with a laser beam in a line pattern. ...