1. Department of Materials Science and Engineering, City University of Hong Kong, Hong Kong SAR 999077, P. R. China
2. Physical Sciences and Engineering Division, Advanced Membranes and Porous Materials (AMPM) Center, King Abdullah University of Science and Technology (KAUST), Thuwal 23955-6900, Saudi Arabia
3. Center of Super-Diamond and Advanced Films (COSDAF), City University of Hong Kong, Hong Kong SAR 999077, P. R. China
4. Department of Chemistry, City University of Hong Kong, Hong Kong SAR 999077, P. R. China