1. Centre for Materials Science and Nanotechnology, Department of Chemistry, University of Oslo, P. O. Box 1033, Blindern, 0315 Oslo, Norway, http://www.mn.uio.no/kjemi/personer/vit/helmerf/
2. SINTEF Materials and Chemistry, P. O. Box 124, Blindern, 0314 Oslo, Norway
3. Institute for Energy Technology, 2027 Kjeller, Norway