1. Key Laboratory of Synthetic and Natural Functional Molecule of the Ministry of Education College of Chemistry & Materials science Northwest University Xi'an 710127 P. R. China
2. Shaanxi Joint Lab of Graphene (NWU) Xi'an 710127 P. R. China
3. State Key Lab Incubation Base of Photoelectric Technology and Functional Materials International Collaborative Center on Photoelectric Technology and Nano Functional Materials Institute of Photonics & Photon‐Technology Northwest University Xi'an 710069 P. R. China