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In this paper, we combine the atomic layer deposition synthesis method of inverse opal with the hydrothermal growth of nanorods. From 460 nm polystyrene nanospheres opal crystals were produced using vertical deposition on Si wafers. The opal templates were covered with ZnO by atomic layer deposition. High temperature annealing was used to remove the polystyrene nanospheres to obtain the inverse opal structure. For the hydrothermal growth of ZnO nanorods, two production routes were analysed: hydrothermal reaction before and after the removal of the template. The two paths produced two distinct structures, one with plate like formations and one with nanorods, respectively. Also, the sample modified by the hydrothermal growth after the annealing showed slight differences in optical properties compared to the regular inverse opal. Morphology, composition and structure of the samples were explored using SEM, EDX and XRD. Optical properties were investigated with reflectance UV–Vis spectroscopy. Thermal stability of the polystyrene opal was determined using TG.

In this study we investigated the material properties of ZnO thin film of ≈ 300 nm thickness, grown on glass and silicon substrates by using atomic layer deposition (ALD) technique. Structural characterization was carried out using incident X-ray diffraction pattern. The microstructural evolution was accompanied by the grain size measurement. A key element of this study was to prove that it is practically impossible to attribute the optical energy gap Eg and the refractive index n dependence to any typical thin film material because these parameters depend on the deposition condition and the program used for determination. Two different values (3.32 and 3.36 eV) for the optical energy gap Eg, and (2.29–2.27) for the refractive index, have been reported and analyzed for ZnO thin film due to the type of behavior of absorbance, transmittance and reflectance. The dielectric characteristics and the AC conductivity were also measured at temperature ranging from (303–413 K0 ) and at frequency range of (1 K Hz to 1 MH). The data of the AC conductivity was analyzed by the universal power law. It was found that the corelated barrier hopping model (CBH) model is the predominate conduction mechanism. This article contains recent advances in the modified ZnO metal oxide prepared by (ALD), for efficient approach for sensor device fabrication depending mainly on the estimated parameters.

In this article, the performance of brass electrode was investigated in a Zn-air (charcoal-based cathode) rechargeable battery. The construction of the battery was carried out with biodegradable materials, namely a cotton cloth diaphragm and carboxymethyl cellulose sodium salt (CMC-Na) viscosity modifier, while the battery skeleton was printed by 3D printing technology. The brass acted as a collector and a preferable surface for the metallic Zn deposition on the brass anode surface. The electrochemical behavior of the brass anode was investigated by cyclic voltammetry (CV). Cyclic performance tests were carried out, which showed stable cell operation even in the presence or absence of additives up to more than 100 cycles. Furthermore, high energy (Eeff) and Coulomb (Ceff) efficiencies, 80% (Eeff), 95% (Ceff), 75% (Eeff), and 95% (Ceff) were obtained, respectively. The Shepherd model was applied to describe the discharging processes of the Zn-air battery containing brass as anode in the presence of additive-free electrolyte or electrolyte with CMC-Na salt additive. It was found that the Shepherd equation described only approximately the resulting discharge curves. In order to attain a more precise mathematical description, stretched exponential function was implemented into the last term of the Shepherd equation. The need for such a correction shows the complexity of the electrochemical processes occurring in these systems. In addition, the surface of the brass anode was also investigated by scanning electron microscopy (SEM) and the composition of the brass alloys was determined by X-ray fluorescence spectroscopy (XRF). Importantly, the formation of dendritic deposition was successfully suppressed and a smooth and uniform surface was obtained after the cycling tests.

The maximization of the number of exposed edges of layered MoS2-type transition metal dichalcogenides of general formula MX2 (M = Mo, W; X = S, Se) is difficult yet meaningful way to improve their electrochemical and electrocatalytic performance. In this work, an all-solid ball milling method for simultaneous introduction of defects and their hybridization through binding of ammonia borane (NH3BH3) to defect sites of MX2 is demonstrated. The milling conditions leads to partial separation and nanosizing of MX2 layers, simultaneously extensively introducing defects (cracks, vacancies, strains, voids etc.), while the detailed analysis revealed the functionalization of the material by binding of NH3BH3 to defect sites, which results in highly improved electrocatalytic performance of thus obtained composites with respect to MX2 for hydrogen evolution reaction. The mechanochemical approach thus enables preparation of MoS2-type materials with improved, highly tunable activity, potentially relevant for energy conversion and storage.

Coupling TiO2 nanofibers with other semiconductor metal oxides can effectively extend the light absorbability of TiO2 to the visible range of the electromagnetic spectrum. This study demonstrates the synthesis of TiO2–MoO3 composite nanofibers via electrospinning using Ti and Mo water-soluble precursors. Aqueous solutions of these precursors were added to a PVP solution in N–N dimethylformamide. The mixture was electrospun, followed by annealing in air at 600 °C obtaining oxide nanofibers. The fibers were characterized via thermogravimetry and differential thermal analysis, X-ray photoelectron spectroscopy, scanning electron microscopy and energy-dispersive X-ray spectroscopy, transmission electron microscopy, Fourier-transform infrared spectroscopy, X-ray diffraction, and Raman spectroscopy. The diameter of the TiO2–MoO3 fibers was between 90 and 110 nm after annealing, Furthermore, methylene blue dye was used to investigate the photocatalytic activity of the fibers in visible light. TiO2–MoO3 fibers showed the best photocalaytic activity with a rate constant of 0.0018 min−1 while pure TiO2 and MoO3 nanofibers had 0.0009 min−1 and 0.0008 min−1 respectively.

In the recent decades, nanomaterials are in the forefront of investigations in the field materials science, due to their beneficial size-dependent properties in many instances. The goal of this work was the development of atomistic models and new computer simulation techniques to describe a phase separation in nanoparticles. For this, new Stochastic kinetic mean-field (SKMF) model was developed. In order to better understand the asymmetric miscibility gap of binary systems the gradient energy coefficient-composition function κ(c) was calculated from the interaction energy V (c) of a solution. This improved SKMF model was applied to simulate a spinodal decomposition and nucleation in Ag-Cu alloy and nanoparticles. The simulations results were compared with experimental observations of Ag-Cu nanoparticles. It was shown that the surface composition values are close to the ones calculated from a single-layer Fowler-Guggenheim approximation. I also demonstrated that this method is able to reproduce the Gibbs-Thomson effect. In addition, a new quantitative multiscale procedure based on the SKMF and phase field models was developed to study the nucleation-growth-coarsening process in alloys., Au cours des dernières décennies, les nanomatériaux sont au premier plan des recherches dans le domaine de la science des matériaux, ceci étant du à leurs propriétés intéressantes liées à leur taille. L’objectif de ce travail a été le développement de modèles atomistiques et de nouvelles techniques de simulations numériques pour décrire la décomposition spinodale dans les nanoparticules. Pour cela, un nouveau modèle stochastique de champ moyen cinétique (Stochastic Kinetic Mean-Field, SKMF) a été développé. Afin de mieux comprendre l’asymétrie de la lacune de miscibilité dans les systèmes binaires Ag-Cu, le coefficient dans l’énergie d’interface κ(c) entre les deux phases en coexistence, dépendant de la concentration, a été calculé à partir de l’énergie d’interaction V(c) de la solution. Ce nouveau modèle SKMF a été appliqué pour simuler une décomposition spinodale et la germination croissance dans d’un alliage Ag-Cu ainsi que dans une nanoparticule. Les résultats de la simulation ont été comparés avec les observations expérimentales de nanoparticules d’Ag-Cu. Il a été montré que la composition de la surface est proche de celle calculée pour une approximation de Fowler-Guggenheim sur une seule couche. Il a aussi été démontré que cette méthode est capable de reproduire l’effet de Gibbs-Thomson. De plus, une nouvelle méthode quantitative multi-échelle basée sur les modèles SKMF et de champ de phase a été développée pour étudier les processus de germination, croissance et coalescence dans les alliages binaires.