1. Division of Chemistry and Biological Chemistry, School of Chemistry, Chemical Engineering and Biotechnology, Nanyang Technological University, 21 Nanyang Link, Singapore 637371, Singapore
2. School of Chemistry and Chemical Engineering, Yangzhou University, Yangzhou, 25002 P. R. China
3. Institute of Materials Research and Engineering, The Agency for Science, Technology and Research (A*STAR), 2 Fusionopolis Way, #08-03, Innovis, Singapore 138634, Singapore
4. Centre for Hydrogen Innovations, National University of Singapore, E8, 1 Engineering Drive 3, Singapore 117580, Singapore