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Malakoutikhah T, Hashemifar SJ, Alaei M. Novel First-Principles Insights into Graphene Fluorination. J Chem Phys 2022; 157:054706. [DOI: 10.1063/5.0091279] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Fluorination of graphene sheets with Xenon difluoride leads to the formation of the widest band gap Gr derivative, namely Fluorographene. Accurate experimental observations distinguish a two stages mechanism in the fluorination procedure, the half-fluorination stage wherein one side of the Gr sheet is rapidly fluorinated and then the full-fluorination stage involving much slower fluorination of the opposite side of the sheet [Nature Comm. 5, 1 (2014)]. Here, we perform comprehensive density functional calculations to illustrate accurate microscopic insights into the much slower rate of the full-fluorination stage, compared with the half-fluorination one. The calculated minimum energy paths for the half- and full-fluorination processes demonstrate much enhanced fluorine adsorption after the half-fluorination stage, which sounds inconsistent with the experimental picture. This ambiguity is explained in terms of significant chemical activation of the graphene sheet after half-fluorination, which remarkably facilitates the formation of chemical contaminants in the system and thus substantially slows down the full-fluorination procedure. After considering the binding energy and durability of the relevant chemical species, including hydrogen, oxygen, and nitrogen molecules and xenon atom, it is argued that oxygen-fluorine ligands are the most likely chemical contaminants opposing the complete fluorination of a graphene sheet. Then, we propose an oxygen desorption mechanism to carefully explain much enhanced rate of the full-fluorination procedure at elevated temperatures. The potential photocatalytic application of the pristine and defected samples in water splitting and carbon dioxide reduction reactions are also discussed.
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Affiliation(s)
| | | | - Mojtaba Alaei
- Isfahan University of Technology, Iran, Islamic Republic of
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Synthesis and Applications of Graphene Oxide. MATERIALS 2022; 15:ma15030920. [PMID: 35160865 PMCID: PMC8839209 DOI: 10.3390/ma15030920] [Citation(s) in RCA: 71] [Impact Index Per Article: 35.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 12/06/2021] [Revised: 01/12/2022] [Accepted: 01/21/2022] [Indexed: 01/27/2023]
Abstract
Thanks to the unique properties of graphite oxides and graphene oxide (GO), this material has become one of the most promising materials that are widely studied. Graphene oxide is not only a precursor for the synthesis of thermally or chemically reduced graphene: researchers revealed a huge amount of unique optical, electronic, and chemical properties of graphene oxide for many different applications. In this review, we focus on the structure and characterization of GO, graphene derivatives prepared from GO and GO applications. We describe GO utilization in environmental applications, medical and biological applications, freestanding membranes, and various composite systems.
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de los Reyes C, Smith McWilliams AD, Hernández K, Walz-Mitra KL, Ergülen S, Pasquali M, Martí AA. Adverse Effect of PTFE Stir Bars on the Covalent Functionalization of Carbon and Boron Nitride Nanotubes Using Billups-Birch Reduction Conditions. ACS OMEGA 2019; 4:5098-5106. [PMID: 31459687 PMCID: PMC6648908 DOI: 10.1021/acsomega.8b03677] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 12/30/2018] [Accepted: 02/21/2019] [Indexed: 06/10/2023]
Abstract
The functionalization of nanomaterials has long been studied as a way to manipulate and tailor their properties to a desired application. Of the various methods available, the Billups-Birch reduction has become an important and widely used reaction for the functionalization of carbon nanotubes (CNTs) and, more recently, boron nitride nanotubes. However, an easily overlooked source of error when using highly reductive conditions is the utilization of poly(tetrafluoroethylene) (PTFE) stir bars. In this work, we studied the effects of using this kind of stir bar versus using a glass stir bar by measuring the resulting degree of functionalization with 1-bromododecane. Thermogravimetric analysis studies alone could deceive one into thinking that reactions stirred with PTFE stir bars are highly functionalized; however, the utilization of spectroscopic techniques, such as Fourier transform infrared spectroscopy and X-ray photoelectron spectroscopy, tells otherwise. Furthermore, in the case of CNTs, we determined that using Raman spectroscopy alone for analysis is not sufficient to demonstrate successful chemical modification.
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Affiliation(s)
- Carlos
A. de los Reyes
- Department
of Chemistry, Department of Chemical and Biomolecular Engineering, Department of Materials
Science and NanoEngineering, Department of Bioengineering,
and Smalley-Curl Institute
for Nanoscale Science and Technology, Rice
University, Houston, Texas 77005, United States
| | - Ashleigh D. Smith McWilliams
- Department
of Chemistry, Department of Chemical and Biomolecular Engineering, Department of Materials
Science and NanoEngineering, Department of Bioengineering,
and Smalley-Curl Institute
for Nanoscale Science and Technology, Rice
University, Houston, Texas 77005, United States
| | - Katharyn Hernández
- Department
of Chemistry, Department of Chemical and Biomolecular Engineering, Department of Materials
Science and NanoEngineering, Department of Bioengineering,
and Smalley-Curl Institute
for Nanoscale Science and Technology, Rice
University, Houston, Texas 77005, United States
| | - Kendahl L. Walz-Mitra
- Department
of Chemistry, Department of Chemical and Biomolecular Engineering, Department of Materials
Science and NanoEngineering, Department of Bioengineering,
and Smalley-Curl Institute
for Nanoscale Science and Technology, Rice
University, Houston, Texas 77005, United States
| | - Selin Ergülen
- Department
of Chemistry, Department of Chemical and Biomolecular Engineering, Department of Materials
Science and NanoEngineering, Department of Bioengineering,
and Smalley-Curl Institute
for Nanoscale Science and Technology, Rice
University, Houston, Texas 77005, United States
| | - Matteo Pasquali
- Department
of Chemistry, Department of Chemical and Biomolecular Engineering, Department of Materials
Science and NanoEngineering, Department of Bioengineering,
and Smalley-Curl Institute
for Nanoscale Science and Technology, Rice
University, Houston, Texas 77005, United States
| | - Angel A. Martí
- Department
of Chemistry, Department of Chemical and Biomolecular Engineering, Department of Materials
Science and NanoEngineering, Department of Bioengineering,
and Smalley-Curl Institute
for Nanoscale Science and Technology, Rice
University, Houston, Texas 77005, United States
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