1. Institute of Materials Chemistry, TU Wien, Getreidemarkt 9, 1060 Vienna, Austria.
2. University Service Center for Transmission Electron Microscopy, TU Wien, Wiedner Hauptstraße 8-10, 1040 Vienna, Austria.
3. Department of Physics and Competence Centre for Catalysis, Chalmers University of Technology, 41296 Göteborg, Sweden.