Electrical Conductivity of Films Formed by Few-Layer Graphene Structures Obtained by Plasma-Assisted Electrochemical Exfoliation of Graphite

Current-voltage characteristics of few-layer graphene structures (FLGS) obtained by plasma-assisted electrochemical exfoliation of graphite in Na2SO4 solution were measured. FLGS are shown to possess electronic conductivity, which indicates the predominant functionalization of the edges of graphene planes and the preservation of the structure of basal planes in obtained nanostructures as in the source graphite. The effect of humidity on the conductivity of FLGS films was studied. The resistance of films was found to increase with an increase in the relative humidity of the environment due to the shielding of FLGS flakes by a film of water. The effect of different solvents on the current-voltage characteristics of FLGS was analyzed. The conductivity of films significantly decreased in vapors of polar protic solvents, while there was a minor effect of nonpolar aprotic solvents on the conductivity of FLGS films

Plasma Electrochemical Synthesis of Graphene-Phosphorene Composite and Its Catalytic Activity towards Hydrogen Evolution Reaction

For the first time, graphene-phosphorene structures were synthesized using the plasma-assisted electrochemical method. The catalytic activity of the composite obtained in the electrolytic plasma mode and its mixtures with few-layer graphene structures toward the hydrogen evolution reaction was studied. A substantial increase in the catalytic activity of the phosphorene structures towards the hydrogen evolution reaction was realized by mixing them with few-layer graphene structures. The catalyst demonstrates excellent activity towards the hydrogen evolution reaction in alkaline media with a low overpotential of 940 mV at a current density of 10 mA·cm−2 and a small Tafel slope of 130 mV dec−1

Plasma Electrochemical Synthesis of Graphene-Phosphorene Composite and Its Catalytic Activity towards Hydrogen Evolution Reaction

For the first time, graphene-phosphorene structures were synthesized using the plasma-assisted electrochemical method. The catalytic activity of the composite obtained in the electrolytic plasma mode and its mixtures with few-layer graphene structures toward the hydrogen evolution reaction was studied. A substantial increase in the catalytic activity of the phosphorene structures towards the hydrogen evolution reaction was realized by mixing them with few-layer graphene structures. The catalyst demonstrates excellent activity towards the hydrogen evolution reaction in alkaline media with a low overpotential of 940 mV at a current density of 10 mA·cm−2 and a small Tafel slope of 130 mV dec−1

Unexpected Room Temperature Ferromagnetism of a Ball-Milled Graphene Oxide—Melamine Mixture

Nitrogen-doped carbon nanomaterial (NDCNM) was synthesized by grinding a mixture of graphene oxide and melamine in a planetary mill with both balls and milling chamber of zirconium dioxide. In the electron spin resonance spectrum of NDCNM, a broad signal with g = 2.08 was observed in addition to a narrow signal at g = 2.0034. In the study using a vibrating-sample magnetometer, the synthesized material is presumably a ferromagnet with a coercive force of 100 Oe. The specific magnetization at 10,000 Oe is approximately 0.020 and 0.055 emu/g at room temperature and liquid nitrogen temperature, respectively

A Facile Synthesis of Noble-Metal-Free Catalyst Based on Nitrogen Doped Graphene Oxide for Oxygen Reduction Reaction

A simple method for the mechanochemical synthesis of an effective metal-free electrocatalyst for the oxygen reduction reaction was demonstrated. A nitrogen-doped carbon material was obtained by grinding a mixture of graphene oxide and melamine in a planetary ball mill. The resulting material was characterized by XPS, EPR, and Raman and IR spectroscopy. The nitrogen concentration on the N-bmGO surface was 5.5 at.%. The nitrogen-enriched graphene material (NbmGO has half-wave potential of −0.175/−0.09 V and was shown to possess high activity as an electrocatalyst for oxygen reduction reaction. The electrocatalytic activity of NbmGO can be associated with a high concentration of active sites for the adsorption of oxygen molecules on its surface. The high current retention (93% for 12 h) after continuous polarization demonstrates the excellent long-term stability of NbmGO

Reduced Graphene Oxide Aerogel inside Melamine Sponge as an Electrocatalyst for the Oxygen Reduction Reaction

A graphene oxide aerogel (GOA) was formed inside a melamine sponge (MS) framework. After reduction with hydrazine at 60 °C, the electrical conductive nitrogen-enriched rGOA-MS composite material with a specific density of 20.1 mg/cm3 was used to fabricate an electrode, which proved to be a promising electrocatalyst for the oxygen reduction reaction. The rGOA-MS composite material was characterized by elemental analysis, scanning electron microscopy, X-ray photoelectron spectroscopy, and Raman spectroscopy. It was found that nitrogen in the material is presented by different types with the maximum concentration of pyrrole-like nitrogen. By using Raman scattering it was established that the rGOA component of the material is graphene-like carbon with an average size of the sp2-domains of 5.7 nm. This explains a quite high conductivity of the composite obtained