The synthesis of large area micro- and nano-structured ZnO surfaces has been successfully achieved through a two-step process. It involves the irradiation of Zn metal sheets with femtosecond laser pulses (350 fs at 1030 nm) at high repetition rates (100-500 kHz), and fast scanning speeds (cm/s). Subsequently, the irradiated sheets are thermally treated in an Argon flux at 380 degrees C, a temperature significantly lower than that typically required for growing micro- and nanostructures in ZnO. Fs-laser irradiation promotes the initial development of topography and the localized oxidation of the metal. This enables the further growth of micro- and nanostructures at preferential sites with good crystalline quality and luminescent properties. Analysis of the material at different processing steps shows that the initial laser-induced oxidation is crucial in defining ZnO growth mechanisms upon thermal treatment, and determining the final properties. We have tested the potential use of these structures as reusable photocalyst. The ease of catalyst recovery in photocatalysis experiments and the degree of degradation achieved may be considered as key performance indicators. Photocatalytic activity tests performed with a Rhodamine B solution showed degradation values up to 43 % over 90 min. The morphology of the samples remains unaltered after photocatalysis experiments.

This paper reports interesting effects on the heterostructures as a function of morphology and electrical properties. The porous silicon layers were synthesized by electrochemical anodization. Different etching times were used to study the properties. Silicon nanocrystals were obtained from the porous silicon by scratching and casting in methanol. The heterostructures were obtained by depositing the nanocrystals on the porous silicon by spin coating. SEM showed the thickness of the porous silicon and the pore size. TEM images showed the size and shape of the nanocrystals. AFM images also showed the nanocrystals. Structural characterization showed the formation of silicon nanocrystals and some silicon oxides. Luminescence spectra showed interesting peaks in different regions of the visible spectrum. Finally, the electrical characterization revealed different behaviors such as ohmic and rectifying an unusual photovoltaic effect. Moreover, the transport mechanism was analyzed and found in the Space Charge Limit Current.

This work focuses on synthesizing neodymium-doped ZnO nano- and microstructures using the vapor-solid method. The efficiency of Nd incorporation into the ZnO lattice has been analyzed. The characterization was carried out using X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), cathodoluminescence (CL), mu-photoluminescence (mu-PL) and Raman Spectroscopy (RS). The formation of the solid solution corresponding to a hexagonal wurtzite phase of ZnO was observed for the samples doped with 1% and 5% wt. Additional phases related to neodymium oxides were also detected in the samples doped with 10% wt. The incorporation of Nd in the Zn lattice has been monitored by means of EDS, CL and XRD. The main changes observed are the increase of the lattice parameter as the Nd content increases, the changes in the morphology of micro- and nanostructures, and the influence on the luminescent properties with higher intensity of Nd intraionic lines.

In recent years, the rapid emergence of antibiotic-resistant bacteria has become a significant concern in the healthcare field, and although bactericidal dressings loaded with various classes of antibiotics have been used in clinics, in addition to other anti-infective strategies, this alarming issue necessitates the development of innovative strategies to combat bacterial infections and promote wound healing. Electrospinning technology has gained significant attention as a versatile method for fabricating advanced wound dressings with enhanced functionalities. This work is based on the generation of polyvinylpyrrolidone (PVP)-based dressings through electrospinning, using a DomoBIO4A bioprinter, and incorporating graphene oxide (GO)/zinc oxide (ZnO) nanocomposites as a potent antibacterial agent. GO and ZnO nanoparticles offer unique properties, including broad-spectrum antibacterial activity for improved wound healing capabilities. The synthesis process was performed in an inexpensive one-pot reaction, and the nanocomposites were thoroughly characterized using XRD, TEM, EDX, SEM, EDS, and TGA. The antibacterial activity of the dispersions was demonstrated against E. coli and B. subtilis, Gram-negative and Gram-positive bacteria, respectively, using the well diffusion method and the spread plate method. Bactericidal mats were synthesized in a rapid and cost-effective manner, and the fiber-based structure of the electrospun dressings was studied by SEM. Evaluations of their antibacterial efficacy against E. coli and B. subtilis were explored by the disk-diffusion method, revealing an outstanding antibacterial capacity, especially against the Gram-positive strain. Overall, the findings of this research contribute to the development of next-generation wound dressings that effectively combat bacterial infections and pave the way for advanced therapeutic interventions in the field of wound care.

Y0.8−xGdxF3:Yb/Er mesocrystals with a biocompatible surface and diverse morphological characteristics were successfully synthesized using chitosan-assisted solvothermal processing. Their structural properties, studied using X-ray powder diffraction, Fourier transform infrared spectroscopy, scanning and transmission electron microscopy and energy dispersive X-ray analysis, were further correlated with the up-conversion emission (λexc = 976 nm) recorded in function of temperature. Based on the change in the visible green emissions originating from the thermally coupled 2H11/2 and 4S3/2 levels of Er3+, the corresponding LIR was acquired in the physiologically relevant range of temperatures (25–50 °C). The detected absolute sensitivity of about 0.0042 °C−1, along with the low cytotoxicity toward both normal human lung fibroblasts (MRC-5) and cancerous lung epithelial (A549) cells, indicate a potential for use in temperature sensing in biomedicine. Additionally, their enhanced internalization in cells, without suppression of cell viability, enabled in vitro labeling of cancer and healthy cells upon 976 nm laser irradiation.

One-dimensional (1D) nanomaterials have garnered significant scientific and technological attention due to their potential applications in electronics devices, gas sensing, energy conversion, and photocatalysis. However, the development of a simple and low-cost technique for 1D nanostructure synthesis remains a challenge. The doping of ZnO nanostructures has proven to be an effective way to improve their internal properties. In this work, one-dimensional ZnO and Ce-doped ZnO nanorods and nanonails were synthesized by a simple thermal evaporation method using different weight ratios of ZnS and CeO2 precursor powders in a catalyst-free process. The effects of cerium doping concentration on the structural, morphological, and optical properties of the as-prepared samples were investigated. XRD analysis confirmed that the crystal structure was converted from the cubic ZnS phase to the hexagonal ZnO phase with increasing annealing temperatures. The UV-Vis spectra showed that the optical absorption edge of Ce-doped ZnO samples was slightly red-shifted. Additionally, the band gap energy decreases with increasing cerium concentration. SEM images showed that the morphology of the structures obtained changed from nanorods to nanonails as the Ce content increased. The incorporation of Ce ions into the ZnO matrix has been successfully confirmed by HRTEM, Raman, and EDX analysis. Photocatalytic activity studies showed that Ce-doped ZnO samples exhibited significantly enhanced photocatalytic performance compared to pure ZnO for the degradation of rhodamine B under UV radiation. These results may suggest the use of heterogeneous photocatalysis as an efficient, cheap, and environment-friendly alternative for the removal of pollutants from water and the use of Ce-doped ZnO as a promising candidate.

Nanostructured ZnO: Nd nanoparticles (NPs) codoped with lithium at low temperature and short synthesis time were prepared using the polyol method, and the influence of different lithium contents at constant atomic concentration of Nd was evaluated. The resulting materials were analyzed by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), Brunauer-Emmett-Teller analysis (BET), X-ray photoelectron spectroscopy (XPS), and optical spectroscopies (photoluminescence (PL), cath-odoluminescence (CL) and Raman). X-ray diffraction patterns demonstrate that the materials are polycrystalline with a wurtzite structure with no secondary phases in the concentrations evaluated. The unit cell parameters were determined, and the crystallite size was calculated considering the three most intense diffraction peaks. TEM shows that the particles are polycrystalline with no amorphization. Raman analysis further confirms the wurtzite hexagonal structure of the particles. Morphological and size studies using SEM and TEM show that the most remarkable change is the evolution from hemispherical ZnO NPs to spindle-shaped particles for Li-Nd doped ZnO. The surface chemistry, as studied by X-ray photoelectron spectroscopy (XPS), confirms the incor-poration of Nd3+. The study of the photocatalytic behavior of the Li-Nd codoped ZnO NPs reveals that the ZNL0.5 sample exhibits the highest photocatalytic activity using a solution of Rhodamine B (2.5 ppm) as a reference.

Ce doped ZnO structures were successfully synthesized by a simple thermal evaporation method, with compacted mixtures of ZnS-CeO2 powders at 1000 °C in a catalyst-free process. The effects of Ce doping on the structural, morphological, and optical properties of the as-prepared samples were investigated. XRD analysis confirmed that high temperature annealing leads to phase transformation from cubic ZnS to hexagonal ZnO. The Uv-Vis spectra showed that the optical absorption edge of Ce doped ZnO samples is slightly red shifted; likewise, the bandgap energy decreases with increasing Ce content. SEM images showed that the morphology of the structures changed from nanorods to nanonails as the Ce concentration increased. HRTEM, Raman, and EDX analysis confirmed the presence of Ce in the ZnO matrix. The results showed that Ce doped ZnO samples exhibited significantly enhanced photocatalytic performance than pure ZnO.

Multi-Wall Carbon Nanotubes (MWCNTs) were analyzed on crystalline silicon substrates (type P) under optimal temperature conditions, using different synthesis times (2, 3, 4, 5, 10, 20, 30, 60, 120, and 180 min) in order to examine the effect on the structural quality and length of the CNTs produced by ultrasonic spray pyrolysis, using pure toluene and ferrocene as precursor solutions under argon flow. Structural, optical, and morphological differences of the MWCNTs grown were analyzed. Raman spectroscopy evidenced the MWCNTs' high quality, noted by the ID/IG (from 0.41 to 0.68) and I2D/IG intensity ratios around 0.75. Morphological differences of the MWCNTs grow evaluated by Field Emission Scanning Electron Microscopy (FE-SEM); the micrographs examined the thickness of CNTs' layers. High-Resolution Transmission Electron Microscopy (HRTEM) technique was used to determine the diameters of CNTs, which were found from 15 to 140 nm. X-Ray Diffraction (XRD) showed two characteristic peaks around 26 degrees and 44 degrees, which corroborated that the MWCNTs were well-graphitized. The influence of the time in these CNTs demonstrated that the final length of these nanotubes could easily reach micrometers. The alienation was better as time increased, and the graphitization extent is good in most cases compared to other more expensive synthesis methods.

In this work, we aim to highlight the increasing interest in semiconductors, particularly ZnO. A revision of the evolution of the scientific production on three selected topics has been conducted. As an indicator of scientific production, the number of publications indexed in the Web of Science Data Base has been used. The search terms selected range from the general to the particular: semiconductors, oxide semiconductors, and ZnO. The period considered is from 1 January 1900 to 6 June 2023. The importance of doping processes in tailoring the properties of these materials, and the relevance of the most recently derived applications are also revised. Since many of the most recent applications that have been developed or are under development refer to optoelecronic properties, doping with rare earth elements has a central role. This was the reason behind choosing the system ZnO doped with Rare Earth elements (Eu, Gd, and Ce) and codoped with Ru to illustrate the materials’ tuning potential of doping processes. Morphology, crystal structure, and luminescent properties have been investigated. Upon doping, both the Near Band Edge and the Deep Level emissions show a remarkable difference due to the change in the relative weight of the components constituting these bands. The spectra in all cases extend over the whole visible range, with a main emission in the violet-blue region corresponding to the Near Band Edge, and a broad band extending from the blue-green to orange-red region associated with the presence of different defects.

There is a general need for alternative structural materials to improve power plants’ efficiency and reduce CO 2 emissions. Within this framework, two new compositions of temperature-resistant sintered ODS ferritic steels (14Cr-5Al-3W), strengthened by a fine dispersion of precipitates (5·10 22 ox. /m 3 ), have been developed. This work focuses on creep properties and microstructure evolution. The creep resistance (at 650°C) could be improved by prior microstructural optimisation, thanks to the consolidation by spark plasma sintering and the tailoring on precipitates’ nature when a single compound introduces the oxide-forming elements (Y-Ti-Zr-O) synthesised for this purpose. To this end, the initial pre-alloyed ferritic powder was mechanically alloyed with the synthetized compound and sintered by spark plasma sintering (SPS). Afterwards, EBSD and TEM characterization were employed to study the microstructures. Small punch creep tests (SPCT) were performed on the steels to study their creep performance. These showed an exceptional enhancement of the creep resistance in the steels containing the Y-Ti-Zr-O additions.

This study presents the advances in the field of ZnO/Ag catalysts from the synthesis of hierarchical ZnO nanowires (NWs) decorated with Ag nanoparticles, prepared by a facile solvothermal method at 120 degrees C. It evaluates the photocatalytic efficiency from studying the time reaction of Ag/Zn concentration ratio and the presence of cetyltrimethylammonium bromide (CTAB) as an organic dispersant. X-ray diffraction, scanning electron microscopy, and analytical/high-resolution transmission electron microscopy results confirmed the presence of homogeneous cylindrical ZnO nanowires and quasi-spherical Ag crystals. ZnO NWs exhibited hexagonal wurtzite structure and cubic FCC symmetry in Ag nanoparticles (NPS). Two types of nanostructures, including homogeneous cylindrical ZnO NWs in the absence of Ag and simultaneous presence of ZnO NWs and Ag NPs, formed depending on experimental conditions. The photocatalytic activity was evaluated by studying methylene blue (MB) degradation time under UV light excitation. Diffuse reflectance UV-Vis spectrophotometry (UV-Vis DRS) allowed identifying the ZnO absorption band at similar to 393 nm. Crystal size varied depending on the reaction time and the addition of CTAB. Synthesis time increased bandgap values, getting better photocatalytic performance in samples synthesized in intermediate times (6 h), higher Ag+/Zn2+ molar ratio (0.2/1.0), and CTAB. According to HRTEM observations, the presence of silver nanocrystals with high content of defects (twinning, stacking faults) could play an essential role in the photocatalytic response. In this context, the specific synthesis conditions of Ag/ZnO might be more appropriate for their use in organic dyes degradation in water and the potential use in protective treatments against materials biodeterioration processes.

This paper reports on the synthesis of Ce-doped ZnO (CZO) nanoparticles (NPs) by an alternative polyol method at low temperature. The method, facile and rapid, uses acetate-based precursors, ethylene glycol as solvent, and polyvinylpyrrolidone as capping agent. The effects of the Ce-doping concentration (ranging from 0 to 8.24 atomic%) on the structural, morphological, compositional, optical, luminescence, and photocatalytic properties of the NPs were investigated by several techniques. The structural findings confirmed that the CZO NPs have a typical hexagonal wurtzite-type structure with a preferred orientation along the (101) plane. The results obtained by Field Emission Scanning Electron Microscopy (FESEM) and Transmission Electron Microscopy (TEM) revealed that the NPs size decreased (from ~30 to ~16 nm) with an increase in the Ce-doping concentration. Energy Dispersive X-Ray Spectroscopy (EDS) and High Resolution Transmission Microscopy (HRTEM) results confirmed the incorporation of Ce ions into the ZnO lattice. Ce-doping influences the photoluminescence (PL) emission compared to that of pure ZnO. The PL emission is related to the presence of different kinds of defects, which could take part in charge transfer and/or trapping mechanisms, hence playing an essential role in the photocatalytic activity (PCA). In fact, in this work we report an enhancement of PCA as a consequence of Ce-doping. In this sense, the best results were obtained for samples doped with 3.24 atomic%, that exhibited a photocatalytic degradation efficiency close to 99% after 60 min ultraviolet (UV) illumination, thus confirming the viability of Ce-doping for environmental applications.

This study refers to the application of in-situ electrochemical synthesis as an alternative method to improve the properties of porous materials against harmful external agents that deteriorate them. It is oriented to an un-derstanding of the effects of crystallisation on the pore structure of different compounds commonly used in the restoration and conservation of porous materials (historical ceramics, building walls, sculptures, or biomedical applications). It analyses the microstructural, chemical details, and stability of the neo-formed phases that modify the pore network. The electrochemical synthesis was carried out at ambient temperature (20 degrees C), over high porous sandstone for crystallising Ca carbonate, Mg carbonate, Ca phosphate, and Ca oxalate compounds. Based on the neo-formed minerals, a comparison was made depending on their specific properties defining how they affected the pore structure. The characterisation included polarised light optical microscopy, environmental and field-emission scanning electron microscopy, digital image analysis, cathodoluminescence (CL-ESEM),en-ergy-dispersive X-ray spectroscopy, and X-ray microdiffraction. Aragonite, hydromagnesite, hydroxyapatite, and whewellite were identified as the majority phases depending on the treatment. Phase transformation, dehy-dration, and dissolution-re-precipitation processes suggested different degrees of stability, including aragonite/ calcite (CaCO3 treatment) and hydromagnesite/magnesite (MgCO3 treatment) transformations and simulta-neous crystallisation of brushite/hydroxyapatite ((Ca-3(PO4)(2) treatment). Electrocrystallisation induced changes in inter-granular porosity, the development of secondary porosity inherent to the minerals, and differences in pore cementation depending on its mineralogy. Among the treatments, Mg carbonate reduced porosity most effectively, followed in descending order by calcium carbonate and calcium phosphate, being the calcium oxalate the less effective.

Electroprecipitation can be considered as a novel consolidation technique that can compete with commercial consolidation treatments, since it allows reduction of its accessible porosity, both superficially and in-depth, increasing considerably its mechanical properties and precipitating a compound chemically compatible with the material to be treated. The purpose of this study is to assess the effectiveness of the electroprecipitation of four different inorganic compounds constituted by magnesium and calcium carbonate, calcium phosphate, and calcium oxalate, in 6 cm thick specimens of quartz-arenite. The suitability of the treatment was assessed in samples treated and aged for 4 years under environmental conditions, comparing the changes caused in structural properties (measuring the ultrasonic pulse velocity, anisotropy, tortuosity, pore size distribution, and mercury accessible porosity), mechanical properties (superficial hardness, uniaxial compressive strength, and drilling resistance) and aesthetic properties (color). In addition, the morphology and composition of the compound precipitated were assessed by XRD and SEM-EDX. This study found that the precipitation of the insoluble compounds by this technique (I) takes place in a homogeneous way, reducing the anisotropy of the material and its tortuosity, which increases the durability of the material against the action of external agents, such as water, soluble salts, and pollutants; (II) increases the mechanical properties and causes a considerable increase in the ultrasonic wave transmission; (III) allows filling almost completely the pores where it precipitates, which reduces the damage risk caused by crystallization pressures; (IV) produced, under these treatment conditions (environmental conditions, confined space and forced precipitation by an electric field), the precipitated phases magnesite, hydromagnesite, calcite, hydroxyapatite, and wewhellite. However, the color changes detected indicate that it is necessary to carry out previous studies in the laboratory to reduce this aesthetic problem, before applying it on-site on a certain material, especially in heritage constructions.

Two electric-arc furnace flue dusts, a waste generated during the steel production process, were characterized and their photocatalytic activity was assessed. Chemical composition by X-ray fluorescence (XRF) analysis identified that both dusts were principally formed by iron, zinc and chromium oxides. Structural characterization carried out by X-ray diffraction patterns (XRD), and micro-Raman measurements demonstrated that ZnFe2O4 (zinc ferrite), FeCr2O4 (chromite) and ZnO (zincite) are present in both waste dusts as majority phases. Scanning electron microscopy (SEM) images showed that both dusts are formed by nanoparticles with a globular and octahedral morphology characteristic of the type of flue dusts formation and the obtained phases. Cathodoluminescence (CL) spectra show the characteristics bands of spinel structure (ZnFe2O4) and Fe3+ emission. X-ray photoelectron spectroscopy (XPS) measurements indicate that Fe ions could be present in 2+ and 3+ oxidation state in the spinel structure, while zinc and chromium ions are in 2+ and 3+, respectively. In addition, the photocatalytic experiments demonstrated that the analyzed samples could be useful as photocatalyzed showing a degradation percentage above 75 %.

In this work, new oxide dispersion strengthened (ODS) ferritic steels have been produced by powder metallurgy using an alternative processing route and characterized afterwards by comparing them with a base ODS steel with Y2O3 and Ti additions. Different alloying elements like boron (B), which is known as an inhibitor of grain growth obtained by pinning grain boundaries, and complex oxide compounds (Y-Ti-Zr-O) have been introduced to the 14Cr prealloyed powder by using mechanical alloying (MA) and were further consolidated by spark employing plasma sintering (SPS). Techniques such as x-ray diffraction (XRD), electron backscatter diffraction (EBSD), and transmission electron microscopy (TEM) were used to study the obtained microstructures. Micro-tensile tests and microhardness measurements were carried out at room temperature to analyze the mechanical properties of the differently developed microstructures, which was considered to result in a better strength in the ODS steels containing the complex oxide Y-Ti-Zr-O. In addition, small punch (SP) tests were performed to evaluate the response of the material under high temperatures conditions, under which promising mechanical properties were attained by the materials containing Y-Ti-Zr-O (14Al-X-ODS and 14Al-X-ODS-B) in comparison with the other commercial steel, GETMAT. The differences in mechanical strength can be attributed to the precipitate’s density, nature, size, and to the density of dislocations in each ODS steel.

ZnO/MWCNT composite thin films were prepared on glass substrates by spray pyrolysis, and their structural and optical behavior were investigated. X-ray diffraction analysis revealed the films hexagonal wurtzite phase with a preferred (002) growth orientation. Photoluminescence spectra of the ZnO film showed two main bands, a UV emission band at 377 nm (3.28 eV) and a broad blue-yellow band at 439–546 nm with a band at 503 nm. Optical transmittance of 80–85% in the visible range was observed in all the films. In the I–V curves, conductivity was improved when incorporating the MWCNT into the zinc oxide. ZnO/MWCNT, at a value of 2 V and irradiated with visible light presented an increased current from 0.6 to 3.2 nA, and a similar pattern was observed when impinging UV light. Film thickness was measured by profilometry, obtaining thicknesses in the range from 143 to 257 nm.

Several phases with variable stoichiometry ZnxMn3−xO4 (with x = 0.25, 0.85 and 1) and ZnO have been obtained from the black mass, a widely generated residue of wasted alkaline batteries. The obtained samples have been characterized by X-ray diffraction (XRD) and Raman spectroscopy showing results consistent with the stoichiometry obtained from chemical analysis. The study of the degradation of methylene blue (MB) and rhodamine B (RhB) under UV radiation demonstrates the photocatalytic behavior in all samples obtained, reaching degradation percentages higher than 70% and 50%, respectively.

In this work, we report on the processing of PVP-capped ZnO nanoparticles employing a simple-polyol method, varying only the molar concentration (0.01 and 0.1 M) of Zn(CH3COO)2•2H2O used as zinc precursor. Synthesis is performed using ethylene glycol (EG) as solvent and polyvinylpyrrolidone (PVP) as capping agent. Physico-chemical characteristics of the as-synthesized particles were studied by X-Ray Diffraction (XRD), Fourier Transform Infrared (FT-IR) spectroscopy, Scanning Electron Microscopy (SEM) and Energy Dispersive Spectroscopy (EDS). SEM micrographs revealed formation of quasi-spherical secondary particles formed by aggregation of primary nanosized subunits crystallized from 0.01 M precursor. When precursor with a higher concentration is used, no aggregation occurs and only tiny primary particles in the nanosized range are obtained. XRD confirmed that ZnO nanoparticles have the hexagonal wurtzite-type structure. SEM, EDS and FT-IR showed that applied route produced ZnO nanoparticles with functionalized surface. Presented results imply clear dependence of the particles morphology and size from precursor concentration which could be used for rapid, continuous, single-step preparation of PVP-capped ZnO nanoparticles tailored in accordance to application demands.