1. Centre for Nanotechnology, Indian Institute of Technology Guwahati, Guwahati, 781039 Assam, India
2. Department of Electronics and Electrical Engineering, Indian Institute of Technology Guwahati, Guwahati, 781039 Assam, India
3. Department of Chemical Engineering, Indian Institute of Technology Guwahati, Guwahati, 781039 Assam, India