1. Energy Research Institute@NTU; Interdisciplinary Graduate School; Nanyang Technological University; 50 Nanyang Drive Singapore 637553 Singapore
2. School of Chemical and Biomedical Engineering; Nanyang Technological University; 62 Nanyang Drive Singapore 637459 Singapore
3. Key Laboratory of Macromolecular Science of Shaanxi Province; Shaanxi Key Laboratory for Advanced Energy Devices; Shaanxi Engineering Lab for Advanced Energy Technology; School of Materials Science and Engineering; Shaanxi Normal University; Xi'an 710062 P. R. China