1. Energy Research & Technology Group, CSIR-Central Mechanical Engineering Research Institute, Durgapur 713209, West Bengal, India
2. Department of Physics, Indian Institute of Technology Guwahati, Guwahati 781039, Assam, India
3. Nanocatalysis Area, Light Stock Processing Division, CSIR-Indian Institute of Petroleum, Dehradun 248005, Uttarakhand, India
4. Centre for Nano Technology, Indian Institute of Technology Guwahati, Guwahati 781039, Assam, India