Massive production of graphene oxide from expanded graphite

In a deviation from the conventional Hummers method, a spontaneous expansion approach was introduced with expanded graphite as the precursors. The intercalating agent (H2SO4) was able to penetrate into the expanded graphite; this had further expanded the graphite and as a result, a foam-like intermediate was produced. The foam-like graphite was more easily oxidized in reaction with the oxidant (KMnO4) to form graphene oxide (GO). Fully exfoliated GO was obtained with expanded graphite having the median diameter ~ 15 {\mu}m as the precursors. This procedure was much safer and productive in scalable applications than the conventional Hummers methods

Effect of encapsulated graphene oxide on alginate-based bead adsorption to remove acridine orange from aqueous solutions

Environmentally-benign high-performance graphene oxide (GO)/alginate-based absorbents were prepared to eliminate acridine orange selected as a typical dye. Characterizations demonstrated GO well encapsulated and its promotion of pore formation on structure. Kinetic studies exhibited that the addition of GO shortened the adsorption equilibrium time, raised the initial rate and the adsorption capacity. Isotherm studies indicated the adsorptive behavior followed Langmuir type, and higher maximum capacity was obtained in the presence of GO. The adsorption positively responded to pH increased from acidic to weakly alkaline. At low pH, GO would contribute dominantly to the adsorption, whereas alginate component was inhibited

CNTs/TiC Reinforced Titanium Matrix Nanocomposites via Powder Metallurgy and Its Microstructural and Mechanical Properties

By using pure titanium powder coated with unbundled multiwall carbon nanotubes (MWCNTs) via wet process, powder metallurgy (P/M) titanium matrix composite (TMC) reinforced with the CNTs was prepared by spark plasma sintering (SPS) and subsequently hot extrusion process. The microstructure and mechanical properties of P/M pure titanium and reinforced with CNTs were evaluated. The distribution of CNTs and in situ formed titanium carbide (TiC) compounds during sintering was investigated by optical and scanning electron microscopy (SEM) equipped with EDS analyzer. The mechanical properties of TMC were significantly improved by the additive of CNTs. For example, when employing the pure titanium composite powder coated with CNTs of 0.35 mass%, the increase of tensile strength and yield stress of the extruded TMC was 157 MPa and 169 MPa, respectively, compared to those of extruded titanium materials with no CNT additive. Fractured surfaces of tensile specimens were analyzed by SEM, and the uniform distribution of CNTs and TiC particles, being effective for the dispersion strengthening, at the surface of the TMC were obviously observed

Facile synthesis of graphene sheets intercalated by carbon spheres for high-performance supercapacitor electrodes

The composites consisting of graphene oxides (GOs) and carbon spheres (CSs), which were hydrothermally derived from the aqueous solution of glucose with average diameter of 200 nm, were mechanically mixed, and the GOs/CSs (GCSs) were thermally treated at high temperatures in the range of 700–900 °C. In the GCS composites, the CSs as spacers located between the GO sheets prevent the aggregation and restacking of graphene sheets. The GCS composites (GO/CS = 1) treated at 800 °C (GCS@800) have the high specific capacitances of 272.8 and 197.5 F g−1 in a three-electrode cell at the current density of 0.2 and 10 A g−1, respectively, in 6 M KOH aqueous solution, and demonstrated high rate capability and good cycling stability. The excellent electrochemical performance of the GCS@800 electrode is attributed to its structure with hierarchical porous structures including overwhelming micropores and a few of macropores. This work provides an effective and simple technique by integrating CSs and graphene sheets into composite structures for high-performance energy storage devices

Chemical and electrochemical study of fabrics coated with reduced graphene oxide

Polyester fabrics coated with reduced graphene oxide (RGO) have been obtained and later characterized by means of chemical and electrochemical techniques. X-ray photoelectron spectroscopy showed a decrease of the oxygen content as well as an increase of the sp2 fraction after chemical reduction of graphene oxide (GO). The electrical conductivity was measured by electrochemical impedance spectroscopy (EIS) and showed a decrease of 5 orders of magnitude in the resistance (¿) when GO was reduced to RGO. The phase angle also changed from 90° for PES-GO (capacitative behavior) to 0° for RGO coated fabrics (resistive behavior). In general an increase in the number of RGO layers produced an increase of the conductivity of the fabrics. EIS measurements in metal/sample/electrolyte configuration showed better electrocatalytic properties and faster diffusion rate for RGO specimens. Scanning electrochemical microscopy was employed to test the electroactivity of the different fabrics obtained. The sample coated with GO was not conductive since negative feedback was obtained. When GO was reduced to RGO the sample behaved like a conducting material since positive feedback was obtained. Approach curves indicated that the redox mediator had influence on the electrochemical response. The Fe(CN)63¿/4¿ redox mediator produced a higher electrochemical response than Ru(NH3)63+/2+ one.Authors thank to the Spanish Ministerio de Ciencia e Innovacion (contract CTM2011-23583) and Universitat Politecnica de Valencia (Vicerrectorado de Investigacion PAID-06-10 contract 003-233) for the financial support. J. Molina is grateful to the Conselleria d'Educacio (Generalitat Valenciana) for the FPI fellowship. A.I. del Rio is grateful to the Spanish Ministerio de Ciencia y Tecnologia for the FPI fellowship. J.C. Galvan is gratefully acknowledged for help with EIS measurements and data analysis.Molina Puerto, J.; Fernández Sáez, J.; Del Río García, AI.; Bonastre Cano, JA.; Cases Iborra, FJ. (2013). Chemical and electrochemical study of fabrics coated with reduced graphene oxide. Applied Surface Science. 279:46-54. https://doi.org/10.1016/j.apsusc.2013.04.020S465427

Synthesis of an ordered mesoporous carbon with graphitic characteristics and its application for dye adsorption

An ordered mesoporous carbon (OMC) was prepared by a chemical vapor deposition technique using liquid petroleum gas (LPG) as the carbon source. During synthesis, LPG was effectively adsorbed in the ordered mesopores of SBA-15 silica and converted to a graphitic carbon at 800 °C. X-ray diffraction and nitrogen adsorption/desorption data and high-resolution transmission electron microscopy (HRTEM) of the OMC confirmed its ordered mesoporous structure. The OMC was utilized as an adsorbent in the removal of dyes from aqueous solution. A commercial powder activated carbon (AC) was also investigated to obtain comparative data. The efficiency of the OMC for dye adsorption was tested using acidic dye acid orange 8 (AO8) and basic dyes methylene blue (MB) and rhodamine B (RB). The results show that adsorption was affected by the molecular size of the dye, the textural properties of carbon adsorbent and surface-dye interactions. The adsorption capacities of the OMC for acid orange 8 (AO8), methylene blue (MB) and rhodamine B (RB) were determined to be 222, 833, and 233 mg/g, respectively. The adsorption capacities of the AC for AO8, MB, and RB were determined to be 141, 313, and 185 mg/ g, respectively. The OMC demonstrated to be an excellent adsorbent for the removal of MB from wastewater.Web of Scienc

Photocatalytic fabrics based on reduced graphene oxide and TiO2 coatings

Supplementary data associated with this article can be found, in the online version, at: http://dx.doi.org/10.1016/j.mseb.2015.04.013The purpose of this work is to obtain photocatalytic fabrics based on reduced graphene oxide (RGO) and TiO2 coatings on polyester fabrics. The influence of the applied number of RGO coatings on properties such as light absorption, conductivity, electroactivity and photocatalytic properties of the fabrics was established. An improvement of these properties with the number of RGO coatings applied was obtained. FESEM, EDX, XPS and FTIR-ATR showed the incorporation of the TiO2 nanoparticles on the fabrics. FTIR-ATR showed the formation of a bidentate carboxylic ligand with titanium atoms. The photocatalytic properties of the fabrics were tested with Rhodamine B dye solutions. Photocatalytic efficiency increased with the number of RGO coatings, due to the increased light absorption, and better electrical properties. The charge transfer resistance (Rct) and its time constant (τ) decreased, indicating a better electron transfer which helps to increase the lifetime of the pair electron/hole.Authors wish to thank to the Spanish Ministerio de Ciencia e Innovación (contract CTM2011-23583) for the financial sup port. J. Molina is grateful to the Conselleria d’Educació, Formació i Ocupació (Generalitat Valenciana) for the Programa VALi+D Postdoctoral Fellowship. Electron Microscopy Service of the UPV (Universitat Politècnica de València) is gratefully acknowledged for help with FESEM and EDX characterization. Timothy Vickers is gratefully acknowledged for help with English revision.info:eu-repo/semantics/publishedVersio

Graphene-based fabrics and their applications: a review

[EN] Graphene has emerged as a revolutionary material in different fields of science and engineering due to its extraordinary properties such as: high electron mobility, high thermal conductivity, mechanical properties, easy functionalization, etc. The field of textiles is continuously integrating new materials to provide fabrics with new functionalities, hence its incorporation on fabrics was a logical step. Its application to the field of textiles has been recently reported, which has allowed the development of textiles with different functionalities such as: antistatic, UV-protecting, electroconductive, photocatalytic, antibacterial, thermal conductivity, energy storage in flexible supercapacitors, electrodes for batteries, sensors, etc. Up to date no review has been written regarding graphene-based fabrics and their applications. The present review aims to fill the existing gap and provide perspectives into the preparation and applications of graphene-based fabrics and yarns.J. Molina wishes to thank to the Spanish Ministerio de Ciencia e Innovacion (contract CTM2011-23583) for the financial support. J. Molina is grateful to the Conselleria d'Educacio, Formacio i Ocupacio (Generalitat Valenciana) for the Programa VALi + D Postdoctoral Fellowship (APOSTD/2013/056).Molina Puerto, J. (2016). Graphene-based fabrics and their applications: a review. RSC Advances. 6:68261-68291. https://doi.org/10.1039/c6ra12365aS6826168291