1. Department of Chemical and Biomolecular Engineering, National University of Singapore, 4 Engineering Drive 4, Singapore 117585, Singapore
2. Joint School of National University of Singapore and Tianjin University, International Campus of Tianjin University, Binhai New City, Fuzhou 350207, China
3. Department of Chemistry, National University of Singapore, 3 Science Drive 3, Singapore 117543, Singapore
4. Eco-materials and Renewable Energy Research Center (ERERC), College of Engineering and Applied Sciences, Nanjing University, No. 22 Hankou Road, Nanjing 210093, China
5. Jiangsu Key Laboratory for Nano Technology, National Laboratory of Solid-State Microstructures, Department of Physics, Nanjing University, No. 22 Hankou Road, Nanjing 210093, China