[1
]Department of NanoEngineering, University of California San Diego, 9500 Gilman Drive,
La Jolla, California 92093, United States
[2
]Research Institute for Sustainable Energy (RISE), TCG Centres for Research and Education
in Science and Technology (TCG CREST), Sector V, Salt Lake, Kolkata 700091, India
[3
]School of Physical Sciences, University of Chinese Academy of Sciences; Laboratory
for Advanced Materials & Electron Microscopy, Institute of Physics, Chinese Academy
of Sciences, Beijing 100190, China