Exfoliation of 2D Materials for Energy and Environmental Applications

The fascinating properties of single-layer graphene isolated by mechanical exfoliation have inspired extensive research efforts toward two-dimensional (2D) materials. Layered compounds serve as precursors for atomically thin 2D materials (briefly, 2D nanomaterials) owing to their strong intraplane chemical bonding but weak interplane van der Waals interactions. There are newly emerging 2D materials beyond graphene, and it is becoming increasingly important to develop cost-effective, scalable methods for producing 2D nanomaterials with controlled microstructures and properties. The variety of developed synthetic techniques can be categorized into two classes: bottom-up and top-down approaches. Of top-down approaches, the exfoliation of bulk 2D materials into single or few layers is the most common. This review highlights chemical and physical exfoliation methods that allow for the production of 2D nanomaterials in large quantities. In addition, remarkable examples of utilizing exfoliated 2D nanomaterials in energy and environmental applications are introduced.     

Local duality theorem for q-ary 1-perfect codes

In this paper, we derive the relationship between local weight enumerator of q-ary 1-perfect code in a face and that in the orthogonal face. As an application of our result, we compute the local weight enumerators of a shortened, doubly-shortened, and triply-shortened q-ary 1-perfect code.     

Dielectric Spectroscopy as a Method for Testing Thin Vanadium Dioxide Films

Technical Physics - We have analyzed the dielectric spectra of thin (1200 Å) films of vanadium dioxide, a material with strong electron–electron correlations. We have tested both undoped...     

Effect of the modification of nanocrystalline MgO aerogels with vanadium and carbon on the destructive sorption of CF2Cl2 and CFCl3

The effect of the promotion of nanocrystalline MgO aerogels with small amounts of vanadium and carbon on the destructive sorption of the Freons CF₂Cl₂ and CFCl₃ was studied. It was found that the introduction of the promoters considerably shortened the induction period of the reaction. The pretreatment of samples modified with vanadium in an oxidizing or reducing atmosphere did not significantly affect the duration of the induction period. It was established that the acceleration of the reaction by fine-particle carbon did not depend on the mutual arrangement of carbon and MgO: on the surface of MgO nanoparticles, in the form of their mechanical mixture, or at separate positions in a reactor. It was concluded that the modifiers catalytically affect the interaction of MgO aerogels with Freons to accelerate the formation of active centers on the surface of their nanoparticles.     

Influence of the Ohmic Contact Structure on the Performance of GaAs/AlGaAs Photovoltaic Converters

A multilayer system of ohmic contacts for GaAs/AlGaAs photovoltaic converters has been developed. A method of ohmic contact blackening is suggested with the aim of improving the coefficient of optical signal reflection from an Ag/Au/Ag multilayer contact. Owing to blackening, the reflection coefficient has been decreased more than tenfold.     

Template‐free anion‐controlled synthesis of Pd (II) nano‐aggregates for the antifouling polymerization of CO and ethylene

The reaction of [(domppp) Pd (OAc)₂] [domppp = 1,3‐bis (di‐o‐methoxyphenylphosphino)propane] and imidazolium‐functionalized carboxylic acids containing various anions (Br^?, PF₆^?, SbF₆^? and BF₄^?) resulted in the formation of nano‐sized Pd (II) aggregates under template‐free conditions. The rate of formation of aggregates can be modulated by changing the anion, affecting the rate of polymerization of CO and olefins without fouling. Herein, we describe the analysis of Pd (II) catalysts by dynamic light scattering, atomic force microscopy, X‐ray photoelectron spectroscopy and X‐ray crystallography, and co‐ and terpolymerization results including the catalytic activity, and bulk density and molecular weight of polymers.