1. Department of Chemical Engineering, Stanford University, Stanford, CA 94305, USA.
2. Department of Electrical Engineering, Stanford University, Stanford, CA 94305, USA.
3. Stanford Synchrotron Radiation Lightsource, SLAC National Accelerator Laboratory, Menlo Park, CA 94025, USA.
4. Department of Civil and Environmental Engineering, Stanford University, Stanford, CA 94305, USA.
5. Samsung Advanced Institute of Technology, Yeongtong-gu, Suwon-si, Gyeonggi-do 443-803, South Korea.