Gold nanoparticles were prepared by electrochemical deposition on highly oriented pyrolytic graphite (HOPG) and boron-doped, epitaxial 100-oriented diamond layers. Using a potentiostatic double pulse technique, the average particle size was varied in the range from 5 nm to 30 nm in the case of HOPG as a support and between <1 nm and 15 nm on diamond surfaces, while keeping the particle density constant. The distribution of particle sizes was very narrow, with standard deviations of around 20% on HOPG and around 30% on diamond. The electrocatalytic activity towards hydrogen evolution and oxygen reduction of these carbon supported gold nanoparticles in dependence of the particle sizes was investigated using cyclic voltammetry. For oxygen reduction the current density normalized to the gold surface (specific current density) increased for decreasing particle size. In contrast, the specific current density of hydrogen evolution showed no dependence on particle size. For both reactions, no effect of the different carbon supports on electrocatalytic activity was observed.

This paper presents an experimental validation of the implementation of a sensor-less control algorithm for a ultra-high permanent magnet synchronous motor by means of an extended Kalman filter, up to 240 000rpm. The considered application is the air compressor for a fuel-cell in an electric car. It is shown that the extended Kalman filter can be used for the ultra-high speed drives, without any loss in accuracy and robustness. Proper experimental results are shown regarding the rotor position accuracy and dynamics of accelerations. The extendibility of the presented algorithm to di erent machines is shown by its implementation with nine di erent motors. In the paper also additional aspects such as the sensitivity of the algorithm towards changes in the back-EMF constant and the impact of temperature variations are considered.

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