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Zinc oxide nanoparticles (ZnONPs) synthesis was studied in multiscale modeling, proposing a reaction-diffusion system based on its three-stage reaction mechanism by the hydrothermal method: (1) dissociation of the precursor, (2) formation of the anion complex, and (3) obtaining the ZnO nanoparticle. Chemical compounds present in the reaction mechanism were evaluated under the Density Functional Theory (DFT) to find its reactivity through the B3LYP/6–311+G method. Reaction-diffusion model Computational simulation and numerical solution allow reproducing ZnONPs three-dimensional morphologies reported experimentally, such as rods, spheres, pseudo-spheres, octahedral, sheet-like, nut-like, and hollow spheres.

This work is focused on making a correlation between results obtained by using spectroscopy and microscopy techniques from single and twofold-layer Silicon-Rich Oxide (SRO) films. SRO films single-layer and twofold-layer characterizations were compared considering the conditions as-grown and with thermal treatment at 1100 &deg, C for 60 min in a nitrogen atmosphere. The thickness of the single-layer film is 324.7 nm while for the twofold-layer film it is 613.2 nm, after heat-treated, both thicknesses decreased until 28.8 nm. X-ray Photoelectron Spectroscopy shows changes in the excess-silicon in single-layer SRO films, with 10% in as-grown films and decreases to 5% for the heat-treated films. Fourier Transform Infrared Spectroscopy (FTIR) exhibits three characteristic vibrational modes of SiO2, as well as, the vibrating modes associated with the Si-H bonds, which disappear after the heat treatment. With UV&ndash, Vis spectroscopy results we obtained the absorbance and the absorption coefficient for the SRO films in order to calculate the optical bandgap energy (Egopt), which increased with heat-treatment. The energy peaks of the photoluminescence spectra were used to calculate the silicon nanocrystal size, obtaining thus an average size of 1.89 &plusmn, 0.32 nm for the as-grown layer, decreasing the size to 1.64 &plusmn, 0.01 nm with the thermal treatment. On the other hand, scanning electron microscopy and high-resolution transmission electron microscopy images confirm the thickness of the twofold-layer SRO films as 628 nm for the as-grown layer and 540 nm for the layer with heat-treatment, and the silicon nanocrystal size of 2.3 &plusmn, 0.6 nm for the films with thermal treatment.

Thin films of nanocomposite of zinc oxide&ndash, reduced graphene oxide (ZnO-rGO) deposited on soda-lime glass substrates were prepared using ultrasonic spray pyrolysis (USP) at 460 &deg, C. The preparation process does not use harsh acids and is environmentally friendly. The deposition period of 2, 3.5 and 5 min resulted in compact, uniform samples with thicknesses of 148, 250 and 365 nm, respectively. After performing structural, morphological, optical and electrical characterization of the prepared nanocomposite, an influence of the deposition time on the physical properties of the obtained films was determined. TEM analyses indicate that the ZnO-rGO nanocomposite presents ZnO nanoparticles anchored on graphene sheets, while XRD, X-ray Photoelectron Spectroscopy (XPS) and Raman results show the presence of a ZnO phase in the ZnO-rGO films. HR-SEM studies showed changes of the ZnO-rGO thin films morphology due to the incorporation of graphene into the ZnO films. Here, the particles of ZnO are similar to small grains of rice and graphene films have the appearance of a little &ldquo, rose&rdquo, As the thickness of the film increases with deposition time, it reduces the structure of resistance of the nanocomposite thin films to 135 &Omega, In addition, the optical transmission of the thin films in the visible region resulted affected. Here, we report a simple methodology for the preparation of ZnO-rGO nanocomposite thin films.

In this work, a novel route is discussed to produce in one step ZnO/Burkeite powders by the modified solution combustion method. The ZnO particles enhance the photocatalytic activity in the degradation of Rhodamine B, in which Burkeite mineral acts as a support due to the pH-dependent morphology of the particle aggregates of the as-synthesized powders. The X-ray diffraction (XRD) characterization shows the presence of a heterostructure: ZnO/Burkeite. The Scanning Electron Microscopy (SEM) image shows a morphological dependence with the pH of the solution used for the synthesis. The results show that the system with the highest degradation (92.4%) corresponds to the case in which ZnO/Burkeite heterostructure was synthesized with a pH 11.

Dilute aqueous solutions of triblock copolymer Pluronic P103 were used to synthesize silver nanoparticles (Ag-NPs) by chemical reduction of silver nitrate (AgNO3) with sodium borohydride (NaBH4). This copolymer was used as a structural agent since monomers act as a stabilizer and micelles act as nanoreactors for nucleation and growth of Ag-NPs. The growth of the nanoparticles (NPs) was monitored by UV-visible spectroscopy on the basis of measuring surface plasmon resonance absorption over a temperature range of 25 to 70°C. Shape and size of hybrid silver/P103 nanomaterials were tuned by varying the micellar structure of Pluronic P103 using a simple synthesis procedure. Dynamic Light Scattering (DLS) and Transmission Electron Microscopy (TEM) were used to study the size and shape of the hybrid nanomaterials. It was observed that Ag-NPs synthesized without Pluronic P103 at 25°C exhibited a great variety of sizes. However, when Pluronic P103 was used below its critical micellar concentration (CMC), spherical-shaped Ag-NPs with uniform size were formed, suggesting that the copolymer had a stabilizing effect. On the other hand, when Ag-NPs were prepared with Pluronic P103 above the CMC, NPs with similar sizes as the micelles were detected, suggesting that the copolymer functioned as a nanoreactor. Furthermore, as temperature reached 35°C, oval-shaped micelles were formed and small NPs were incorporated into the crown of the micelles. Independent Ag-NPs were not observed since they used the surface of the micelles as a soft template. Therefore, it was possible to obtain tiny Ag-NPs with homogeneous size.

The search for novel materials and the development of improved processes for water purification have attracted the interest of researchers worldwide and the use of titanium dioxide in photocatalytic processes for the degradation of organic pollutants contained in water has been one of the benchmarks. Compared to crystalline titanium dioxide (cTiO2), the amorphous material has the advantages of having a higher adsorption capacity and being easier to dope with metal and non-metal elements. In this work, we take advantage of these two features to improve its photocatalytic properties in the degradation of Rhodamine B. The structural characterization by XRD analysis gives evidence of its amorphous nature and the SEM micrographs portray the disc morphology of 300 nm in diameter with heterogeneous grain boundaries. The degradation of Rhodamine B tests with the amorphous TiO2 using visible light confirm its improved catalytic activity compared to that of a commercial product, Degussa P25, which is a well-known crystalline material.

The fundamental aspects of the manufacturing of gold nanoparticles (AuNPs) are discussed in this review. In particular, attention is devoted to the development of a simple and versatile method for the preparation of these nanoparticles. Eco-friendly synthetic routes, such as wet chemistry and biosynthesis with the aid of polymers, are of particular interest. Polymers can act as reducing and/or capping agents, or as soft templates leading to hybrid nanomaterials. This methodology allows control of the synthesis and stability of nanomaterials with novel properties. Thus, this review focus on a fundamental study of AuNPs properties and different techniques to characterize them, e.g., Transmission Electron Microscopy (TEM), Atomic Force Microscopy (AFM), UV-Visible spectroscopy, Dynamic Light Scattering (DLS), X-Ray Diffraction (XRD), X-Ray Photoelectron Spectroscopy, Small-angle X-Ray Scattering (SAXS), and rheology. Recently, AuNPs obtained by “green” synthesis have been applied in catalysis, in medicine, and as antibacterials, sensors, among others.