1. Institute of Advanced Synthesis, Nanjing Tech University, 30 Puzhu South Road, Nanjing 211800, P. R. China
2. School of Materials Science and Engineering, Nanyang Technological University, 50 Nanyang Avenue, 639798 Singapore
3. Nanyang Environment and Water Research Institute (NEWRI), Interdisciplinary Graduate School (IGS), Nanyang Technological University, 1 Cleantech Loop, CleanTech One, 637141 Singapore
4. Solar Fuels Laboratory, Nanyang Technological University, 50 Nanyang Avenue, 639798 Singapore
5. Institute of Chemical and Engineering Sciences A*STAR, 1 Pesek Road, 627833 Singapore