Ruthenium nanodendrites on reduced graphene oxide: an efficient water and 4-nitrophenol reduction catalyst

A green and efficient protocol is reported for the elegant design of reduced graphene oxide (rGO)-supported Ru nanodendrites for promotion of electrochemical water reduction in a wide pH range as well as for environmental remediation.

Porous Fiber Processing and Manufacturing for Energy Storage Applications

The objective of this article is to provide an overview on the current development of micro- and nanoporous fiber processing and manufacturing technologies. Various methods for making micro- and nanoporous fibers including co-electrospinning, melt spinning, dry jet-wet quenching spinning, vapor deposition, template assisted deposition, electrochemical oxidization, and hydrothermal oxidization are presented. Comparison is made in terms of advantages and disadvantages of different routes for porous fiber processing. Characterization of the pore size, porosity, and specific area is introduced as well. Applications of porous fibers in various fields are discussed. The emphasis is put on their uses for energy storage components and devices including rechargeable batteries and supercapacitors.

Hierarchical Electrospun and Cooperatively Assembled Nanoporous Ni/NiO/MnOx/Carbon Nanofiber Composites for Lithium Ion Battery Anodes

A facile method to fabricate hierarchically structured fiber composites is described based on the electrospinning of a dope containing nickel and manganese nitrate salts, citric acid, phenolic resin, and an amphiphilic block copolymer. Carbonization of these fiber mats at 800 °C generates metallic Ni-encapsulated NiO/MnOx/carbon composite fibers with average BET surface area (150 m(2)/g) almost 3 times higher than those reported for nonporous metal oxide nanofibers. The average diameter (∼900 nm) of these fiber composites is nearly invariant of chemical composition and can be easily tuned by the dope concentration and electrospinning conditions. The metallic Ni nanoparticle encapsulation of NiO/MnOx/C fibers leads to enhanced electrical conductivity of the fibers, while the block copolymers template an internal nanoporous morphology and the carbon in these composite fibers helps to accommodate volumetric changes during charging. These attributes can lead to lithium ion battery anodes with decent rate performance and long-term cycle stability, but performance strongly depends on the composition of the composite fibers. The composite fibers produced from a dope where the metal nitrate is 66% Ni generates the anode that exhibits the highest reversible specific capacity at high rate for any composition, even when including the mass of the nonactive carbon and Ni(0) in the calculation of the capacity. On the basis of the active oxides alone, near-theoretical capacity and excellent cycling stability are achieved for this composition. These cooperatively assembled hierarchical composites provide a platform for fundamentally assessing compositional dependencies for electrochemical performance. Moreover, this electrospinning strategy is readily scalable for the fabrication of a wide variety of nanoporous transition metal oxide fibers.

Evaporation-induced Self-assembly Process Controlled for Obtaining Highly Ordered Mesoporous Materials with Demanded Morphologies

A large number of periodic mesoporous materials have been reported using amphiphilic organic molecules with increasing development of synthetic methods for mesostructural, morphological, and compositional designs. The evaporation-induced self-assembly (ESIA) process to fabricate ordered mesoporous films is one of the most essential synthetic methods, which has extensively been applied for obtaining a wide variety of samples (e.g., films and monoliths, including powders). It contains complicated physical variations and chemical reactions, but has been simply explained by several research groups. However, a current, exact understanding of such complicated systems should be given with respect to all the variations and reactions. In this article, I have mainly surveyed the exact EISA process by considering the difference between simple and controlled EISA processes on the basis of my own experiments. I believe that the insights are consequently helpful for obtaining highly ordered mesoporous materials with demanded morphologies.