Materials For Storage Applications Research Articles

Hydrothermal Method–Derived MnMoO4 Crystals: Effect of Cationic Surfactant on Microstructures and Electrochemical Properties

AbstractThe development of energy devices is becoming necessary to deal with the power crisis. Binary transition manganese molybdate (MnMoO4) is considered to be a well‐known material for storage applications. Electrochemical performance of anode electrode materials was tested with respect to the effect of cationic surfactant cetyltrimethylammonium bromide (C19H12BrN). The fundamental characterization studies such as X‐ray diffraction, photoluminescence, Raman, and Fourier transform infrared confirmed the presence of MnMoO4. The scanning electron microscopic (SEM) images revealed well‐grained micro/nanostructures. The electrochemical behavior was determined by cyclic voltammetry (CV), galvanostatic charge‐discharge (GCD), and electrochemical impedance spectroscopy studies. In this study, 0.2 M CTAB/MnMoO4 showed high 447.61 F/g specific capacitance from the CV analysis. The GCD studies showed that after 3000 cycles, the cycling stability was retained with 79.60% of capacitive retention.

(Invited) Low Pressure and Atmospheric Pressure Plasma Interactions with Molten Metals and Liquid Droplets for Materials Processing

Several grand challenges in energy storage and conversion need the discovery functional materials that many agree will be composed of complex compositions and nanoscale materials such as nanowires. In this regard, plasma based materials processing has been shown to be promising for combinatorial techniques and scalable processing. For example, our group has shown that gentle plasma excitation of gas phase will allow the use of non-catalytic, low melting metals for catalyzing nanowire growth. Furthermore, the use of plasma oxidation of liquid precursors allows for creation of metastable complex oxide particles with compositional control. A number of examples will be discussed in which the above two techniques are currently being used for accelerating the development of a variety of catalysts including electrocatalysts and materials for storage applications. This talk will highlight our efforts to understand the role of plasmas under two categories: (a) the synergistic effects hydrogen and nitrogen plasma interactions with molten metals; and (b) the oxygen plasma-liquid droplet interactions. To gain insights into these mechanisms we have studied the interaction of hydrogen and nitrogen plasmas with low melting point metals, primarily with gallium. Absorption/desorption experiments as well as theoretical-computational calculations were performed. Experiments have shown an increment of adsorbed gaseous species into the molten metal in the presence of plasmas; furthermore, Density Functional Theory (DFT) calculations suggest a strong interaction between atomic hydrogen and molten gallium that is described as a high absorption on the surface, rapid diffusion and a steady state concentration of the gas inside the bulk. In the case of oxygen plasma-liquid droplet interactions for creating complex oxides, the role of solvated electrons and oxygen radicals will be discussed. Acknowledgements Author acknowledge primary funding support from NSF Solar Project (DMS 1125909), NSF EPSCoR (1355438). Acknowledge with Dr. Miran Mozetic and Dr. Uros Cvelbar for helpful technical discussions regarding measurements. The presentation includes contributions from Dr. Maria Carreon who is currently at U. of Tulsa.

DESCRIPTION OF CHEMICALLY AND THERMALLY TREATED MULTI-WALLED CARBON NANOTUBES USING SEQUENTIAL DECOMPOSITION OF ADSORPTION ISOTHERMS

The effect of wet acid oxidation by means of sulfuric/nitric acid mixtures, and high-temperature treatment of commercial arc-discharge synthesized multi-walled carbon nanotubes (MWCNTs) was studied. In order to analyze the adsorption capacities of differently treated MWCNTs, we employed a multistep method that considers separately different pressure ranges (zones) on the experimentally obtained isotherms. The method is based on simple gas isotherm measurements (N2, CO2, CH4, etc.). Low pressure ranges can be described using Dubinin’s model, while high pressure regimes can be fitted using different models such as BET multilayer and Freundlich equations. This analysis allows to elucidate how different substrate treatments (chemical and thermal) can affect the adsorbate–adsorbent interactions; moreover, theoretical description of adsorbate–adsorbate interactions can be improved if a combination of adsorption mechanisms are used instead of a unique model. The results hereby presented also show that, while MWCNTs are a promising material for storage applications, gas separation applications should carefully consider the effect of wide nanotube size distribution present on samples after activation procedures.

A review of thin film media for magnetic recording

Thin film materials and deposition techniques used for the manufacturing of high density magnetic recording disks are reviewed. Novel metal alloys and oxide thin films developed for high density horizontal and vertical recording technologies are listed, and their manufacturing processes are compared. Electroless and electrolytic plating, and sputter deposition techniques are briefly described with emphasis on the advantages and limitations of each technology. A discussion of research areas with potential for future developments in materials for storage applications is also presented.