Aerogels Based on Graphene Oxide with Addition of Carbon Nanotubes: Synthesis and Properties

Nowadays numerous sorbents based on graphene and other carbon nanomaterials have been synthesized for the removal or collecting of oil remains due to its unique physico-chemical properties. Obtaining of aerogels based on graphene oxide and carbon nanotubes with addition of chitosan solution as a binder component is shown in this paper. Aerogels were synthesized by reduction of aqueous dispersion of graphene oxide using the reducing agents, followed by ultrasonic and thermal treatment. Ultrasound destroys the graphene layers, decreasing them in size, thereby exposing new layers to form edges that already have no stabilizing carboxyl groups, which are located at the edges, and participate in the formation of bonds. The surface morphology of obtained aerogels was studied by SEM. The study of the sorption capacity showed that graphene/CNTs aerogel is characterized by short absorption time and high sorption ability that depend on densities of the used solvents. All experimental results show the possibility of using the aerogels based on graphene and CNTs as sorbents for collection of oil residues

Sum Frequency Generation Spectroscopy Study of an Ionic Liquid at a Graphene-BaF₂ (111) Interface

Sum frequency generation (SFG) vibrational spectroscopy and contact angle measurements of an ionic liquid, 1-butyl-3-methylimidazolium dicyanamide [BMIM]­[DCA], at solid–liquid interfaces are reported. Bare solid single crystal BaF₂ (111) surface, a single and few layer graphene-coated BaF₂ (111) surface are used as the solid substrates. The SFG results indicate that both [BMIM]⁺ and [DCA]⁻ can be detected specifically on the graphene-coated BaF₂ (111) surface, without coating only [DCA]⁻ are observed. [DCA]⁻ anions are attracted to the positively charged BaF₂ (111) surface and occupy the first layer at the solid–liquid interface. The graphene coating shields the charged crystal surface and allows both cations and anions to exist at the interface. Furthermore, increase in the contact angle of BaF₂ surface after graphene layers deposition suggests that the graphene coating lowers the surface energy

Molecular response of 1-butyl-3-methylimidazolium dicyanamide ionic liquid at the graphene electrode interface investigated by sum frequency generation spectroscopy and molecular dynamics simulations

The ion distribution at the charged three layer graphene-ionic liquid (1-butyl-3-methylimidazolium dicyanamide, [BMIM][DCA]) interface is probed by sum frequency generation spectroscopy (SFG), cyclic voltammetry (CV), and electrochemical impedance spectroscopy (EIS). The SFG results show the presence of both [BMIM]+ cations and [DCA]- anions at the charged graphene surface, where the anion signal increased with the increasing external potential and the cation signal was little influenced by the external potential. The CV and EIS results suggest that ions form an electrically stable double layer at the charged graphene surface. Molecular dynamics simulations of [BMIM][DCA] near the charged graphene surface suggest that the interface consists of alternating layers of cations and anions that restructure with external potential variation. The experimental data can be interpreted by a double-layer model where the anionic and cationic layers interchange position with each other at the surface depending on the applied potential