Affiliation: | a Institute of Energy and Environment Materials, School of Physics and Engineering, Sun Yat-Sen University, 135 Xingang West, Guangzhou 510275, PR China b Department of Physics and Materials Sciences, City University of Hong Kong, 83 Tat Chee Avenue, Kowloon, Hong Kong c School of Mechanical and Production Engineering, Nanyang Technology University, North Sprine 639798, Singapore |