1. School of Chemistry, University of Hyderabad, Hyderabad 500046, India
2. School of Electronic Science and Engineering, and State Key Laboratory of Electronic Thin Films and Integrated Devices, University of Electronic Science and Technology of China, Chengdu 610054, P.R. China
3. Department of Inorganic Chemistry, University of Madras, Chennai 600025, India
4. School of Science, and Institute of Oxygen Supply, Tibet University, Lhasa 850000, P.R. China