1. Guangzhou Institute of Energy Conversion, Chinese Academy of Sciences, Guangzhou 510640, P. R. China
2. Key Laboratory of Renewable Energy, Chinese Academy of Sciences, Guangzhou 510640, P. R. China
3. Guangdong Key Laboratory of New and Renewable Energy Research and Development, Guangzhou 510640, P. R. China
4. University of Chinese Academy of Sciences, Beijing 100049, P. R. China
5. College of Materials and Energy, South China Agricultural University, Guangzhou 510642, P. R. China