1. Department of Chemistry and Bio-X, Stanford University, Stanford, CA 94305
2. Department of Chemical Engineering, National Chung Cheng University, Chia-Yi 62102, Taiwan
3. Department of Electrical Engineering, National Chung Cheng University, Chia-Yi 62102, Taiwan
4. Department of Chemical Engineering, National Taiwan University of Science and Technology, Taipei 10607, Taiwan
5. National Synchrotron Radiation Research Center, Hsinchu 30076, Taiwan
6. Department of Electrical and Electronic Engineering, The University of Hong Kong, Hong Kong 999077, China