Oxidation resistance of graphene-coated Cu and Cu/Ni alloy

The ability to protect refined metals from reactive environments is vital to many industrial and academic applications. Current solutions, however, typically introduce several negative effects, including increased thickness and changes in the metal physical properties. In this paper, we demonstrate for the first time the ability of graphene films grown by chemical vapor deposition to protect the surface of the metallic growth substrates of Cu and Cu/Ni alloy from air oxidation. SEM, Raman spectroscopy, and XPS studies show that the metal surface is well protected from oxidation even after heating at 200 \degree C in air for up to 4 hours. Our work further shows that graphene provides effective resistance against hydrogen peroxide. This protection method offers significant advantages and can be used on any metal that catalyzes graphene growth

Transparent self-assembled films of reduced graphene oxide platelets

Transparent conducting films have been fabricated in one step, combining self-assembly and chemical reduction of graphene oxide platelets dispersed in water. The films are of centimeter scale and their thickness can be controlled by the concentration of the graphene oxide suspension. The optical transmittance values at a wavelength of 550 nm were 87% and 96% for the films made from 1.5 and 0.5 mg/ml suspensions, respectively, and have sheet resistances of 11.3 and 31.7 k/square. Scanning and transmission electron microscopy, atomic force microscopy, and x-ray photoelectron spectroscopy were used to characterize the films

Catalyst-Free Synthesis and Characterization of Metastable Boron Carbide Nanowires

Catalyst-free growth of boron carbide nanowires is achieved by pyrolysis of diborane and methane at 650-750 degrees C and around 500 mTorr in a quartz tube furnace. Electron-diffraction analysis using a novel diffraction-scanning transmission electron microscopy (D-STEM) technique indicates that the crystalline nanowires are single-crystal orthorhombic boron carbide. TEM images show that the nanowires are covered by a 1-3 nm thick amorphous layer of carbon. Elemental analysis by electron energy loss spectroscopy (EELS) shows only boron and carbon while energy-dispersive X-ray spectroscopy (EDX) and X-ray photoelectron spectroscopy (XPS) show the presence of oxygen as well as boron and carbon

Hydrazine-reduction of graphite-and graphene oxide

A B S T R A C T We prepared hydrazine-reduced materials from both graphite oxide (GO) particles, which were not exfoliated, and completely exfoliated individual graphene oxide platelets, and then analyzed their chemical and structural properties by elemental analysis, XPS, TGA, XRD, and SEM. Both reduced materials showed distinctly different chemical and structural properties from one another. While hydrazine reduction of graphene oxide platelets produced agglomerates of exfoliated platelets, the reduction of GO particles produced particles that were not exfoliated. The degree of chemical reduction of reduced GO particles was lower than that of reduced graphene oxide and the BET surface area of reduced GO was much lower than that of reduced graphene oxide

Hydrazine-reduction of graphite- and graphene oxide

We prepared hydrazine-reduced materials from both graphite oxide (GO) particles, which were not exfoliated, and completely exfoliated individual graphene oxide platelets, and then analyzed their chemical and structural properties by elemental analysis, XPS, TGA, XRD, and SEM. Both reduced materials showed distinctly different chemical and structural properties from one another. While hydrazine reduction of graphene oxide platelets produced agglomerates of exfoliated platelets, the reduction of GO particles produced particles that were not exfoliated. The degree of chemical reduction of reduced GO particles was lower than that of reduced graphene oxide and the BET surface area of reduced GO was much lower than that of reduced graphene oxide

Microwave assisted exfoliation and reduction of graphite oxide for ultracapacitors

We report a simple yet versatile method to simultaneously achieve the exfoliation and reduction of graphite oxide. By treating graphite oxide powders in a commercial microwave oven, reduced graphite oxide materials could be readily obtained within 1 min. Extensive characterizations showed that the as-prepared materials consisted of crumpled, few-layer thick and electronically conductive graphitic sheets. Using the microwave exfoliated graphite oxide as electrode material in an ultracapacitor cell, specific capacitance values as high as 191 F/g have been demonstrated with KOH electrolyte

Chemical analysis of graphene oxide films after heat and chemical treatments by X-ray photoelectron and Micro-Raman spectroscopy

Several nanometer-thick graphene oxide films deposited on silicon nitride-on silicon substrates were exposed to nine different heat treatments (three in Argon, three in Argon and Hydrogen, and three in ultra-high vacuum), and also a film was held at 70 degrees C while being exposed to a vapor from hydrazine monohydrate. The films were characterized with atomic force microscopy to obtain local thickness and variation in thickness over extended regions. X-ray photoelectron spectroscopy was used to measure significant reduction of the oxygen content of the films; heating in ultra-high vacuum was particularly effective. The overtone region of the Raman spectrum was used, for the first time, to provide a "fingerprint" of changing oxygen content