Graphene Growth on Electroformed Copper Substrates by Atmospheric Pressure CVD.

Chemical vapor deposition (CVD) is regarded as the most promising technique for the mass production of graphene. CVD synthesis under vacuum is the most employed process, because the slower kinetics give better control on the graphene quality, but the requirement for high-vacuum equipment heavily affects the overall energy cost. In this work, we explore the possibility of using electroformed Cu substrate as a catalyst for atmospheric-pressure graphene growth. Electrochemical processes can produce high purity, freestanding metallic films, avoiding the surface defects that characterize the rolled foils. It was found that the growth mode of graphene on the electroformed catalyst was related to the surface morphology, which, in turn, was affected by the preliminary treatment of the substrate material. Suitable conditions for growing single layer graphene were identified.

Electrochemical Characterization of Magnetite (Fe3O4) Nanoaggregates in Acidic and Alkaline Solutions.

The electrochemical behavior of magnetite (Fe3O4) aggregates with submicrometric size is investigated. Specifically, cyclic voltammetry tests were performed in both acidic (pH ∼ 4.5) and alkaline (pH ∼ 12.8) solutions, exploiting a conventional three-electrode cell. In the first case, the working electrode was made of a glassy carbon substrate loaded with magnetite nanoaggregates, forming a continuous film. In a second configuration, magnetite nanoaggregates were dispersed in solution, kept under stirring, as a fluidized electrode. The latter approach showed an increase in the electrochemical response of the particles, otherwise limited by the reduced active area as in the former case. Electrochemical-atomic force microscopy (EC-AFM) investigation was carried out in an acidic environment, showing the topography evolution of nanoaggregates during the electrochemical characterization. X-ray diffraction (XRD) analysis was carried out to evaluate the microstructural variation in the Fe3O4 electrodes after cathodic polarization tests in an alkaline environment.

Electrochemical scanning probe analysis used as a benchmark for carbon forms quality test.

Carbon forms (graphite, pyrolytic graphite, highly oriented pyrolytic graphite (HOPG), glassy carbon, carbon foam, graphene, buckypaper, etc) are a wide class of materials largely used in technology and energy storage. The huge request of carbon compounds with reliable and tunable physical and chemical properties is tackled by contriving new production protocols and/or compound functionalizations. To achieve these goals, new samples must be tested in a trial-and-error strategy with techniques that provide information in terms of both specimen quality and properties. In this work, we prove that electrochemical scanning probe techniques allow testing the performances of carbon compounds when are used as an electrode inside an electrochemical cell. Comparing the results with a reference sample (namely, HOPG) gives an insight on defects in the specimen structure, performances, and possible applications of the new samples. In this study, we concentrate on traditional carbon forms already employed in many fields versus new recently-developed specimens, in view of possible applications to the field of energy storage.