Tunable Synthesis of Predominant Semi-Ionic and Covalent Fluorine Bonding States on a Graphene Surface

Abstract

In this study, fluorinated graphene (FG) was synthesized via a hydrothermal reaction. Graphene oxides (GOs) with different oxygen bonding states and oxygen contents (GO(F), GO(P), and GO(HU)) were used as starting materials. GO(F) and GO(P) are commercial-type GOs from Grapheneall. GO(HU) was prepared using a modified Hummers method. The synthesized FGs from GO(F), GO(P), and GO(HU) are denoted as FG(F), FG(P), and FG(HU), respectively. The F atoms were bound to the graphene surface with predominantly semi-ionic or covalent bonding depending on the GO oxygen state. FG(F) and FG(HU) exhibited less extensive fluorination than FG(P) despite the same or higher oxygen contents compared with that in FG(P). This difference was attributed to the difference in the C=O content of GOs because the C=O bonds in GO primarily produce covalent C–F bonds. Thus, FG(F) and FG(HU) mainly exhibited semi-ionic C–F bonds. The doped F atoms were used to tune the electronic properties and surface chemistry of graphene. The fluorination reaction also improved the extent of reduction of GO.

Symmetrical Diacetylenes Outfitted with Ionic Liquid-like Groups: Structural, Polymerization, and Carbonization Studies

“…XPS measurements show that both elements are present in the sample. Three types of environments are found for sulfur, C–S–C, S–O, and C–SO x –C ( x = 2, 3), ,− and two kinds of environments are detected for fluorine, semi-ionic C–F and CF 3 . ,− Thus, the present work shows that carbonization of ionic diacetylenes may be an alternative method to introduce doping elements in a graphite structure …”

One-Stage Process of Reduction, Fluorination, and Doping with Nitrogen of Graphene Oxide Films

“…Peaks at 964 and 1538, 1602 and 1722 cm –1 , 1451 and in the range 2500–2950 cm –1 , as well as in the range 2950–3750 cm –1 are associated with vibrations of the carbon skeleton, CC bonds, vibrations of oxygen-containing functional groups CO, vibrations of carbon single bonds in sp 3 hybridization of C–H, CH, CH 2 , and CH 3 , as well as hydroxyl groups adsorbed on the sample surface, respectively . The new line at 1111 cm –1 is associated with the appearance of the C–F bond . It should be noted that the ratio of the intensities of the peaks associated with CC and CO vibrations is close to 1, which indicates a weak degree of removal of oxygen groups with a double bond when ascorbic acid is used to reduce RGOF.…”

“…44 The new line at 1111 cm −1 is associated with the appearance of the C−F bond. 45 It should be noted that the ratio of the intensities of the peaks associated with C�C and C�O vibrations is close to 1, which indicates a weak degree of removal of oxygen groups with a double bond when ascorbic acid is used to reduce RGOF.…”

“…XPS spectra of GO clearly show peaks at 285.3 eV (CC), 286 eV (C–C), 287.6 eV (CO/C–OH), and 289.1 eV (OC–OH) . In the RGOF sample, the peak at 288.6 eV is associated with fluorine groups . After replacing the ascorbic acid-reducing agent with hydrazine, one more peak appears in the spectra of the RGOFN samples: at 286.9 eV (C–N/CN). , …”

Fundamentals of Li/CFxbattery design and application

“…126 Lee et al compared three types of GOs with various O-group contents and demonstrated that O-groups featuring sp 3 -hybridised carbon, such as C–O–C and CO, favoured the formation of covalent C–F bonds via fluorination, whereas carboxyl and hydroxyl groups easily detached from the carbon skeleton and generated sp 2 -hybridised active centres, which promoted the formation of semi-ionic C–F bonds. 128…”