1. Solid State and Structural Chemistry Unit, Indian Institute of Science, Bangalore 560012, India
2. Department of Physics, Indian Institute of Science, Bangalore 560012, India
3. Renewable and Sustainable Energy Institute, University of Colorado Boulder, Boulder, Colorado 80309, United States
4. School of Chemistry and Biochemistry, Georgia Institute of Technology, Atlanta, Georgia 30332-0400, United States
5. Department of Chemical and Biological Engineering and Department of Chemistry, University of Colorado Boulder, Boulder, Colorado 80309, United States
6. Centre for Nano Science and Engineering, Indian Institute of Science, Bangalore 560012, India