1. Materials Science and Engineering Program, University of California, San Diego, La Jolla, CA 92093, USA.
2. Department of Mechanical and Aerospace Engineering, University of California, San Diego, La Jolla, CA 92093, USA.
3. Department of NanoEngineering, University of California, San Diego, La Jolla, CA 92093, USA.
4. Sustainable Power and Energy Center, University of California, San Diego, La Jolla, CA 92093, USA.