1. Department of Chemistry and Nebraska Center for Materials and Nanoscience, University of Nebraska—Lincoln, Lincoln, Nebraska 68588, United States
2. School of Science and Engineering of Materials, Hefei University of Technology, Hefei, Anhui 230009, China
3. Department of Physics, Tsinghua University, Beijing 100084, China
4. Department of Materials Science and Engineering and Hefei National Lab for Physical Materials at Microscale, University of Science and Technology of China, Hefei, Anhui 230026, China