1. Department of Chemical and Petroleum Engineering, University of Pittsburgh, Pittsburgh, Pennsylvania 15261, United States
2. Department of Mechanical Engineering and Materials Science, University of Pittsburgh, Pittsburgh, Pennsylvania 15261, United States
3. Department of Materials Science and Engineering, The Ohio State University, Columbus, Ohio 43210, United States
4. Environmental TEM Catalysis Consortium (ECC), University of Pittsburgh, Pittsburgh, Pennsylvania 15261, United States
5. Department of Physics, University of Washington, Seattle, Washington 98195, United States
6. Department of Physics and Astronomy, University of Pittsburgh, Pittsburgh, Pennsylvania 15261, United States