1. School of Materials and Energy, Chongqing Key Laboratory for Advanced Materials and Technologies of Clean Energies Southwest University Chongqing 400715 P. R. China
2. Department of Mechanical Engineering National University of Singapore Singapore 117575 Singapore
3. School of Physical and Mathematical Sciences Nanyang Technological University Singapore 637371 Singapore
4. Key Laboratory of Luminescent and Real‐Time Analytical Chemistry (Southwest University), Ministry of Education Southwest University Chongqing 400715 P. R. China
5. Department of Physics National University of Singapore Singapore 117542 Singapore