1. Department of NanoEngineering, University of California San Diego, La Jolla, California 92093, United States
2. Department of Physics, Florida A&M University, Tallahassee, Florida 32307, United States
3. Center for Functional Nanomaterials, Brookhaven National Laboratory, Upton, New York 11973, United States
4. Key Laboratory of Material Physics, Ministry of Education, Department of Physics and Engineering, Zhengzhou University, Zhengzhou 450052, China
5. Department of Chemical Engineering, Columbia University, New York, New York 10027, United States
6. Chemistry Division, Brookhaven National Laboratory, Upton, New York 11973, United States
7. Program of Chemical Engineering, University of California San Diego, La Jolla, California 92093, United States