PtCo3/C catalysts for oxygen reduction were prepared and heat-treated between 350 and 1000 °C under reductive conditions. The catalysts were activated by cyclic voltammetry, which resulted in the partial oxidative leaching of cobalt. Subsequent rotating disk electrode measurements showed a maximum mass activity for samples tempered at 800 °C, which yielded a 2.4 times higher activity than commercial PtCo x /C. TEM images revealed that the particle size of the PtCo3/C catalysts remains almost constant until a temperature of 600 °C is reached; a further temperature increase leads to a noticeable particle growth and a broadening of the particle size distribution. XRD measurements showed that heat treatment leads to the formation of fcc-Pt, Pt3Co, fct-PtCo, fcc-PtCo, and cobalt. The fct- and fcc-PtCo phases are present in samples with the highest catalytic activities.

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In this paper, we report on the outcome of a German network project conducted with 12 partners from universities and research institutes on the material development of dye solar cells (DSC). We give an overview in the field and evaluate the concept of monolithic DSC further with respect to upscaling and producibility on glass substrates. We have developed a manufacturing process for monolithic DSC modules which is entirely based on screen printing. Similar to our previous experience gained in the sealing of standard DSC, the encapsulation of the modules is achieved in a fusing step by soldering of glass frit layers. For use in monolithic DSC, a platinum free, conductive counter electrode layer, showing a charge transfer resistance of R CT < 1Á5 V cm 2 , has been realized by firing a graphite/carbon black composite under an inert atmosphere. Glass frit sealed monolithic test cells have been prepared using this platinum-free material. A solar efficiency of 6% on a 2Á0 cm 2 active cell area has been achieved in this case. Various types of non-volatile imidazolium-based binary ionic liquid electrolytes have been synthesized and optimized with respect to diffusion-limited currents and charge transfer resistances in DSC. In addition, quasi-solid-state electrolytes have been successfully tested by applying inorganic (SiO 2 ) physical gelators. For the use in semi-transparent DSC modules, a polyol process has been developed which resulted in the preparation of screen printed, transparent catalytic platinum layers showing an extremely low charge transfer resistance (0Á25 V cm 2 ).