1. Energy Research Institute, Nanyang Technological University, Singapore 637553
2. School
of Physical and Mathematical Sciences, Nanyang Technological University, Singapore 637371
3. Institute of Materials Research and Engineering, 3 Research Link, Singapore 117602
4. School of Materials Science and Engineering, Nanyang Technological University, Singapore 637553
5. Singapore-Berkeley Research Initiative for Sustainable Energy (SinBeRISE), 1 Create Way, Singapore 138602