Laser-ablation-assisted SF6 decomposition for extensive and controlled fluorination of graphene

Abstract

We present a safe, clean, convenient, and easy-to-control method for extensive fluorination of graphene using laser-ablation-assisted decomposition of gaseous SF 6 molecules. The decomposition process is based on irradiation of a silicon target using a Nd:YAG laser (532 nm) in an SF 6 atmosphere. The reactive species produced in the plume above the silicon target are consequently responsible for fluorination of graphene placed in proximity to the plume.The applicability of the proposed method is demonstrated on fluorination of CVD-grown graphene on copper foil. Samples with different fluorination levels were evaluated using Xray photoelectron spectroscopy and Raman spectroscopy. The influence of the applied number of laser pulses on the nature of the C-F bonds, fluorine, and sulphur concentrations, as well as graphene damage, is discussed. The method enables control of fluorine content by simple counting of laser pulses. We show that a fluorination level corresponding to a stoichiometry up to CF1.4 can be achieved. The fluorination does not lead to the formation of Cu-F in contrast to previously published approaches.

Recent Advances in Fluorinated Graphene from Synthesis to Applications: Critical Review on Functional Chemistry and Structure Engineering

“…Recently, a series of plasma sources like SF 6 , CF 4 , and F 2 were employed in the plasma fluorination. [100,[126][127][128][129][130][131][132] Wang et al developed the synthesis of FG by using CF 4 plasma to fluorinate the unilaminar graphene nanosheets from chemical vapor deposition (CVD) method. By controlling the reaction conditions, FGs with different fluorine coverage were produced and the fluorine distribution on graphene was highly heterogenous.…”

“…Compared with the fluorination of graphene by directly using CF 4 plasma, this method was performed more gently and the consumption of fluorine sources was much smaller. [128] Xu et al utilized SF 6 plasma fluorine source to fluorinate the CVD-grown graphene and directly constructed the FG/Si heterojunction for photodetection (Figure 5C). [100] Yang et al investigated the fluorination process of graphene under the SF 6 plasma exposure with a layer-dependent characteristic.…”

“…The fluorine content is the simplest and fundamental character of FG, which has been introduced in the above intrinsic properties section. [94,104,122,123,128,130,236] Herein, we mainly aim at the recent processes about the engineering of other structural characters such as fluorine distribution, fluorine type, radicals, interlayer structure, and present how do the corresponding performances and applications be regulated and optimized.…”

“…Recently, a series of plasma sources like SF 6 , CF 4 , and F 2 were employed in the plasma fluorination. [ 100,126–132 ] Wang et al. developed the synthesis of FG by using CF 4 plasma to fluorinate the unilaminar graphene nanosheets from chemical vapor deposition (CVD) method.…”

“…Reproduced with permission. [ 128 ] Copyright 2019, Elsevier. C) Schematic diagram of the fluorination procedure and the corresponding XPS spectra and Raman spectra.…”