Multifunctional Macroassembled Graphene Nanofilms with High Crystallinity
Li Peng, Ying Han, Meihui Wang, Xiaoxue Cao, Junfeng Gao, Yingjun Liu, Xianjue Chen, Bin Wang, Bo Wang, Chongyang Zhu, Xiao Wang, Ke Cao, Ming Huang, Benjamin V. Cunning, Jintao Pang, Wendao Xu, Yibin Ying, Zhen Xu, Wenzhang Fang, Yang Lü, Rodney S. Ruoff, Chao Gao
Abstract
Abstract A “cooling–contraction” method to separate large‐area (up to 4.2 cm in lateral size) graphene oxide (GO)‐assembled films (of nanoscale thickness) from substrates is reported. Heat treatment at 3000 °C of such free‐standing macroscale films yields highly crystalline “macroassembled graphene nanofilms” (nMAGs) with 16–48 nm thickness. These nMAGs present tensile strength of 5.5–11.3 GPa (with ≈3 µm gauge length), electrical conductivity of 1.8–2.1 MS m −1 , thermal conductivity of 2027–2820 W m −1 K −1 , and carrier relaxation time up to ≈23 ps. As a demonstration application, an nMAG‐based sound‐generator shows a 30 µs response and sound pressure level of 89 dB at 1 W cm −2 . A THz metasurface fabricated from nMAG has a light response of 8.2% for 0.159 W mm −2 and can detect down to 0.01 ppm of glucose. The approach provides a straightforward way to form highly crystallized graphene nanofilms from low‐cost GO sheets.