^aKey Laboratory for Intelligent Nano Materials and Devices of the Ministry of Education, State Key Laboratory of Mechanics and Control of Mechanical Structures, Nanjing University of Aeronautics and Astronautics, Nanjing 210016, China

^bDepartment of Applied Physics, The Hong Kong Polytechnic University, Hong Kong, China

^cSchool of Physics, Southeast University, Nanjing 211189, China

^dCollege of Jincheng, Nanjing University of Aeronautics and Astronautics, Nanjing 211156, China

^eSchool of Physics and Technology, Nanjing Normal University, Nanjing 210023, China

^fDepartment of Chemistry, National University of Singapore, Singapore 117543, Singapore

^gInstitute of Materials Research and Engineering, Agency for Science, Technology and Research (A*STAR), Innovis 138634, Singapore

^hGlobal Innovative Centre for Advanced Nanomaterials, College of Engineering, Science and Environment, The University of Newcastle, Newcastle NSW 2308, Australia