1. Department of Physics and Astronomy University of California, Irvine Irvine CA 92697 USA
2. Institute for New Energy Materials & Low-Carbon Technologies and Tianjin Key Lab of Photoelectric Materials & Devices School of Materials Science and Engineering Tianjin University of Technology Tianjin 300384 China
3. Department of Mining and Materials Engineering McGill University Montreal H3A 0C5 Canada
4. Chemistry Division Brookhaven National Laboratory Upton NY 11973 USA
5. Institute of Industrial Catalysis College of Chemical Engineering Zhejiang University of Technology Hangzhou China
6. School of Materials Science and Engineering Xi'an University of Technology Xi'an 710048 China
7. State Key Laboratory of Coal Conversion Institute of Coal Chemistry Chinese Academy of Sciences Taiyuan 030001 China