1. Institute of Surface Chemistry and CatalysisUlm University 89069 Ulm Germany
2. Hefei National Laboratory for Physical Sciences at the MicroscaleKey Laboratory of Surface and Interface Chemistry and Energy Catalysis of Anhui Higher Education Institutes and Department of Chemical PhysicsUniversity of Science and Technology of China 230026 Hefei P. R. China
3. Central Facility for Electron MicroscopyUlm University 89069 Ulm Germany