1. Department of Electrical Engineering Eindhoven University of Technology P.O. Box 513 Eindhoven MB 5600 The Netherlands
2. Institute of Energy and Climate Research Forschungszentrum Jülich (IEK‐9) D‐52425 Jülich Germany
3. Institute of Physical Chemistry RWTH Aachen University D‐52074 Aachen Germany
4. Centre for Clean Energy Technology University of Technology Sydney Broadway Sydney NSW 2007 Australia