1. Institute for Clean Energy and Advanced Materials; Faculty of Materials and Energy; Southwest University; Chongqing 400715 China
2. Division of Physics and Applied Physics; School of Physical and Mathematical Sciences; Nanyang Technological University; Singapore 637371 Singapore
3. Chongqing Key Laboratory for Advanced Materials and Technologies of Clean Energies; Chongqing 400715 China
4. Institute of Materials Science and Devices; Suzhou University of Science and Technology; Suzhou 215011 China