Multifunctional Macroassembled Graphene Nanofilms with High Crystallinity.

Peng, Li; Han, Ying; Wang, Meihui; Cao, Xiaoxue; Gao, Junfeng; Liu, Yingjun; Chen, Xianjue; Wang, Bin et al. · Adv Mater · 2021

basic_science · Level V

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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<sup>-1</sup> , thermal conductivity of 2027-2820 W m<sup>-1</sup> K<sup>-1</sup> , 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<sup>-2</sup> . A THz metasurface fabricated from nMAG has a light response of 8.2% for 0.159 W mm<sup>-2</sup> 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.