1. Building Energy Research Group Department of Building and Real Estate The Hong Kong Polytechnic University Hung Hom Kowloon Hong Kong 999077 China
2. School of Mechanical Engineering Beijing Institute of Technology Beijing 100081 China
3. State Key Laboratory of Automotive Safety and Energy Tsinghua University Beijing 100084 China
4. Department of Materials Science and Engineering City University of Hong Kong 83 Tat Chee Avenue Kowloon Hong Kong 999077 China
5. Department of NanoEngineering University of California San Diego La Jolla CA 92093 USA
6. Sustainable Power and Energy Center (SPEC) University of California San Diego La Jolla CA 92093 USA