1. Department of Mechanical Engineering, The University of Hong Kong, Pokfulam, Hong Kong;
2. HKU-Zhejiang Institute of Research and Innovation (HKU-ZIRI), Hangzhou, Zhejiang 311300, China
3. Energy Research Institute, Shandong Academy of Sciences, Jinan, Shandong 250014, China
4. HKU-Zhejiang Institute of Research and Innovation (HKU-ZIRI), Hangzhou, Zhejiang 311300, China e-mail: