1. Nanotechnology Research Laboratory, College of Engineering and Computer Science, The Australian National University, ACT 2601, Australia
2. Laboratory of Advanced Nanomaterials for Sustainability, College of Engineering and Computer Science, The Australian National University, ACT 2601, Australia
3. Department of Applied Physics, The Hong Kong Polytechnic University, Hong Kong, Hong Kong Special Administrative Region of the People's Republic of China
4. Research School of Electrical, Energy and Materials Engineering, The Australian National University, ACT 2601, Australia