We have investigated the storage capability of microporous carbon materials for gaseous hydrogen both theoretically and experimentally. In the grand canonical Monte Carlo calculation the hydrogen molecules are physisorbed by van der Waals interactions with the surface atoms of carbon slitpores and carbon nanotubes. At room temperature the optimum pore geometry is a slitpore consisting of two graphite platelets separated by a distance that corresponds approximately to two times the diameter of a hydrogen molecule. In this case for a storage pressure of 10 MPa a maximum adsorbed hydrogen density of 14 kg/m 3 can be reached, which corresponds to a gravimetric storage capacity of 1.3 wt %. Only for low gas pressure a cylindrical geometry like that in carbon nanotubes can exceed the storage density of carbon slitpores owing to capillary forces.

Recent research indicates a severe discrepancy between oxygen evolution reaction catalysts dissolution in aqueous model systems and membrane electrode assemblies. This questions the relevance of the widespread aqueous testing for real world application. In this study, we aim to determine the processes responsible for the dissolution discrepancy. Experimental parameters known to diverge in both systems are individually tested for their influence on dissolution of an Ir-based catalyst. Ir dissolution is studied in an aqueous model system, a scanning flow cell coupled to an inductively coupled plasma mass spectrometer. Real dissolution rates of the Ir OER catalyst in membrane electrode assemblies are measured with a specifically developed, dedicated setup. Overestimated acidity in the anode catalyst layer and stabilization over time in real devices are proposed as main contributors to the dissolution discrepancy. The results shown here lead to clear guidelines for anode electrocatalyst testing parameters to resemble realistic electrolyzer operating conditions.

The direct carbon fuel cell (DCFC) is a special type of high temperature fuel cell which allows direct conversion of the chemical energy of different carbon materials into electricity. The thermodynamic efficiency of this process is high, and thus the overall conversion efficiency has the potential to exceed these of other fuel cell concepts. Until now the most developed DCFC-systems are based on molten carbonate or hydroxide as electrolyte. In this publication we show that also for a system with a solid electrolyte such as in solid oxide fuel cells (SOFC), which suffers, in principle, from limited contact between the solid fuel and the solid electrolyte, significant conversion rates can be achieved at such interfaces. The principal aspects of the direct electrochemical conversion of carbon powders in an SOFC-system have been investigated in the temperature range of 800 C to 1000 C. It has been shown that using a flat planar anode, carbon conversion rates exceeding 100 mA cm À2 are possible. Different solid fuels have been investigated in order to determine the influence of carbon properties on the electrochemical conversion.

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