The process of oxidation of a copper surface coated by a layer of graphene in water-saturated air at 50 °C was studied where it was observed that oxidation started at the graphene edge and was complete after 24 h. Isotope labeling of the oxygen gas and water showed that the oxygen in the formed copper oxides originated from water and not from the oxygen in air for both Cu and graphene-coated Cu, and this has interesting potential implications for graphene as a protective coating for Cu in dry air conditions. We propose a reaction pathway where surface hydroxyl groups formed at graphene edges and defects induce the oxidation of Cu. DFT simulation shows that the binding energy between graphene and the oxidized Cu substrate is smaller than that for the bare Cu substrate, which facilitates delamination of the graphene. Using this process, dry transfer is demonstrated using poly­(bisphenol A carbonate) (PC) as the support layer. The high quality of the transferred graphene is demonstrated from Raman maps, XPS, STM, TEM, and sheet resistance measurements. The copper foil substrate was reused without substantial weight loss to grow graphene (up to 3 cycles) of equal quality to the first growth after each cycle. It was found that dry transfer yielded graphene with less Cu impurities as compared to methods using etching of the Cu substrate. Using PC yielded graphene with less polymeric residue after transfer than the use of poly­(methyl methacrylate) (PMMA) as the supporting layer. Hence, this dry and clean delamination technique for CVD graphene grown on copper substrates is highly advantageous for the cost-effective large-scale production of graphene, where the Cu substrate can be reused after each growth.

The direct formation of CN and CO bonds from inert gases is essential for chemical/biological processes and energy storage systems. However, its application to carbon nanomaterials for improved energy storage remains technologically challenging. A simple and very fast method to form CN and CO bonds in reduced graphene oxide (RGO) and carbon nanotubes (CNTs) by an ultrasonic chemical reaction is described. Electrodes of nitrogen- or oxygen-doped RGO (N-RGO or O-RGO, respectively) are fabricated via the fixation between N or O carrier gas molecules and ultrasonically activated RGO. The materials exhibit much higher capacitance after doping (133, 284, and 74 F g for O-RGO, N-RGO, and RGO, respectively). Furthermore, the doped 2D RGO and 1D CNT materials are prepared by layer-by-layer deposition using ultrasonic spray to form 3D porous electrodes. These electrodes demonstrate very high specific capacitances (62.8 mF cm and 621 F g at 10 mV s for N-RGO/N-CNT at 1:1, v/v), high cycling stability, and structural flexibility.

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The development of new materials, having exceptional properties in comparison to existing materials is highly required for bringing advancement in electronic and optoelectronic technologies. Keeping this fact, we investigated structural, electronic, and optical properties of zincblende GaN doped with selected Zn concentrations (6.25%, 12.50%, and 18.70%), using the first-principle calculations based on density functional theory with GGA + U. We conducted the entire study using the WIEN2K code. In this study, we calculated various significant parametric quantities such as cohesive energies, formation energies, bulk moduli, and lattice constants along with the study of optical and electronic properties by substituting Ga atoms with Zn atoms in 1 × 2 × 2 supercell. The structural stability is confirmed by studying the phonon dispersion curves which suggest that Zn:GaN material is stable against the 6.25% and 18.70% Zn concentrations while for 12.50%, it shows instability. The Hubbard values U = 0, 2, 4, 6 eV were added to GGA and the electronic properties were improved with the U = 6 eV. Optical absorption was blue shifted while the refractive index and dielectric constant were increased with increasing the Zn concentrations. Electronic properties are enhanced due to the prime contribution of cations (Zn) 3d states. The optical and electronic properties are further discussed in detail in the entire study.

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