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The water oxidation in alkaline media is a kinetically sluggish process and it requires an active electrocatalyst for overall water splitting which is a challenging task to date. Herein, we formulate a platform for the design of efficient NiCo2S4/C nanocomposite using earth abundant and nonprecious materials. The nanocomposites are prepared by scale up hydrothermal method using different carbon contents from acid dehydrated sucrose. They are structurally and morphologically characterized by various analytic techniques. The scanning electron microscopy has shown few microns flower-like morphology of nanocomposite and hexagonal crystalline phase is identified by X-ray diffraction (XRD). Further, high-resolution transmission electron microscopy supported the XRD results, and C, Ni, Co and O elements were found in the composition nanocomposite as investigated by energy-dispersive spectroscopy. The most active nanocomposite reaches a current density of 20 mA·cm−2 at potential of 285 mV vs reversible hydrogen electrode. The nanocomposite is kinetically supported by 61 mV·dec−1 as small Tafel slope. The nanocomposite is stable and durable for 40 h. The electrochemical impedance spectroscopy described a small charge transfer resistance of 188.4 Ω. These findings suggest that the NiCo2S4/C nanocomposite could be used as a promising material for an extended range of applications particularly in energy technology.

The purpose of this study is the assessment of the properties of compound SnmOn clusters (m=1, 2, 3, 4 and n=1,..,10) and is justified by the theoretical and practical importance of the crystalline stannic oxides and of the related silicon-oxygen systems. The optimized structure is obtained from the minimization of the total energy evaluated using the Density Functional Theory. The quantities analyzed are the cluster structure, its binding energy, the spatial distribution of the electronic charge and the density of states. This analysis indicates that the cluster structure consists on two approximately separate sublattices. In agreement with this central feature, the size dependence of the parameters of the electronic charge is well described by superposing the corresponding values for the elemental clusters.

In this work we present a study of the properties of defective nanostructures. The material chosen to this purpose, i.e. SnO2, has practical applications and many of them rely on the spontaneous formation of vacancies. Therefore, crystalline grains with shape and size comparable to the experimental ones have been considered. According to the bulk properties, the grains lattice has the rutile structure and may also include vacancy defects. The calculations describe the effects of the structural grain parameters, i.e. size and shape, as well as of the defect type, on the grain cohesion and are based on a Tight Binding method. The comparison with Density Functional calculations, also carried out in the course of this study, illustrates the limits of both methods when used for these complex structures.

The development of tunable spherical aberration (Cs) imaging correctors for medium-voltage transmission electron microscopes (TEM) offers new opportunities for atomic-scale in-vestigations of materials. A very interesting class of microstructures regarding a variety of dif-ferent physical properties are the transition metal dichalcogenide misfit layer compounds exhibit-ing a high density of incommensurate interfaces due to their stacked nature. In the present study, the benefits coming along with the set-up of negative CS imaging (NCSI) conditions (in TEM) are demonstrated by means of different examples regarding local inhomogeneities in (PbS)1.14NbS2 crystals that can not be dissected in such detail by averaging x-ray techniques.

The focus of this study is on the adsorption properties of the nanocrystalline materials and SnO2 has been chosen as the appropriate example. Therefore model structures consisting on SnO2 grains with a rutile lattice and a size comparable with the experimental ones have been considered and the adsorbed system is generated by depositing a CO molecule above a tin or oxygen atom on the grain surface. The calculations, based on semi-empirical Hartree-Fock and scattering theories, illustrate the dependence of the binding and adsorption energies of grains on their size and shape and show the effects of these energies on the grain conductance.