[1
]Guangdong Provincial Key Laboratory of New and Renewable Energy Research and Development,
Guangzhou 510640, P. R. China
[2
]University of Chinese Academy of Sciences, Beijing 100049, P. R. China
[3
]Nano Science and Technology Institute, University of Science and Technology of China,
Suzhou 215123, P. R. China
[4
]Tibet New Energy Research and Demonstration Centre, Lhasa, Tibet 850000, P. R. China