1. Engineering Research Center of Nano‐Geomaterials of Ministry of EducationFaculty of Materials Science and ChemistryChina University of Geosciences Wuhan 430074 China
2. Department of Electronic EngineeringThe Chinese University of Hong Kong Shatin, New Territories, 999077 Hong Kong SAR China
3. Department of Materials Science and Engineering and Centre for Functional Photonics (CFP)City University of Hong Kong Kowloon Hong Kong SAR 999077 China
4. School of Materials Science and EngineeringGeorgia Institute of Technology Atlanta GA 30332 USA