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The rational combination of plasmonic and all-dielectric concepts within hybrid nanomaterials provides a promising route toward devices with ultimate performance and extended modalities. Spectral matching of plasmonic and Mie-type resonances for such nanostructures can only be achieved for their dissimilar characteristic sizes, thus making the resulting hybrid nanostructure geometry complex for practical realization and large-scale replication. Here, we produced amorphous TiO2 nanospheres decorated and doped with Au nanoclusters via single-step nanosecond-laser irradiation of commercially available TiO2 nanopowders dispersed in aqueous HAuCl4. Fabricated hybrids demonstrate remarkable light-absorbing properties (averaged value ≈96%) in the visible and near-IR spectral range mediated by bandgap reduction of the laser-processed amorphous TiO2 as well as plasmon resonances of the decorating Au nanoclusters. The findings are supported by optical spectroscopy, electron energy loss spectroscopy, transmission electron microscopy, and electromagnetic modeling. Light-absorbing and plasmonic properties of the produced hybrids were implemented to demonstrate catalytically passive SERS biosensor for identification of analytes at trace concentrations and solar steam generator that permitted to increase water evaporation rate by 2.5 times compared with that of pure water under identical 1 sun irradiation conditions.

In the present work, bismuth-based nanoparticles of various compositions were obtained by pulsed laser ablation of a metallic bismuth target in water and air using a Q-switch Nd:YAG laser (wavelength of 1064 nm, pulse duration of 7 ns, frequency of 20 Hz, and pulse energy of 160 mJ). Then the samples were annealed in air at temperatures up to 600°C. A comparative analysis of the obtained powders was carried out using methods of X-ray diffraction, transmission electron microscopy, specific surface area measurements, IR-Fourier and UV-Vis Spectroscopy. The photocatalytic activity of the synthesized materials in the process of Rhodamine B decomposition under irradiation of a LED source (375 nm) was also studied.

Here, we demonstrate formation of spherical-shaped amorphous titania (TiO2) nanoparticles decorated with Au nanoclusters via nanosecond pulse ablation (7-ns, 532-nm wavelength) of commercially available TiO2 nanopowders dispersed in an aqueous solution of chloroauric acid (HAuCl4). Generation of such hybrid nanostructures was found to be caused by laser-induced remelting of the initial TiO2 nanoparticles, stimulated by Au nanoclusters that can adsorbed on their surface and boost light-to-heat conversion process in optically transparent titania. The morphology and chemical composition of the obtained hybrid nanomaterials were studied in detail via scanning electron microscopy, Raman spectroscopy and Energy Dispersive X-ray spectroscopy. The average size and number of Au nanoclusters reduced on the TiO2 nanoparticle surface was shown to be tuned by varying the initial nanoparticles/HAuCl4 concentration ratio. Spectroscopic measurements of single hybrid nanoparticles scattering, as well as the corresponding numerical calculations of electromagnetic fields structure near their surface indicate synthesized functional nanomaterials as extremely promising for numerous applications of modern optics, optoelectronics and nanophotonics, e.g., realization of advanced chemo-and biosensing platforms, as well as of new-generation solar cells.

Antibacterial composites based on linen and NPs obtained by pulsed laser ablation of a zinc target in air were synthesized at various concentrations of the active component (ZnO NPs). The surface morphology and optical properties of ZnO/linen composites were investigated by scanning electron microscopy and UV-visible spectroscopy. The antibacterial activity of ZnO/linen composites was tested on S.aureus in accordance with ISO 20743:2013. It was found that the antibacterial activity depends on the concentration of ZnO NPs. High antibacterial activity of the composites was achieved when the concentration of the active component was of 0.25 mg/cm2. At a concentration of 0.1 mg/cm2 the composites showed only a bacteriostatic effect. The use of photoactivation of composites by LED radiation of 365 nm for 10 min led to an increase in antibacterial activity about 1.5 times for the samples in both concentrations.

Highly active and stable catalysts are very crucial for boosting the oxygen evolution reaction (OER) and converting water into clean fuel. Here, we adopt the laser ablation in liquid technique to p...

Bifunctional electrocatalysts for both hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) are very crucial for converting water into clean fuel through overall water splitting. H...

Different methods (the wetness impregnation of Ag and Pd precursors dissolved in water or acetonitrile solution, and the double solvent impregnation technique) were employed to immobilize Ag&ndash, Pd nanoparticles (NPs) into the pores of the microporous zirconium-based metal-organic framework known as UiO-66. The obtained materials were characterized by using nitrogen adsorption-desorption at &minus, 196 &deg, C, powder X-ray diffraction, UV-Vis diffusion reflectance spectroscopy, and transition electron microscopy measurements. Special attention was paid to the acid and redox properties of the obtained materials, which were studied by using temperature-programmed desorption of ammonia (TPD-NH3) and temperature-programmed reduction (TPR-H2) methods. The use of a drying procedure prior to reduction was found to result in metallic NPs which, most likely, formed on the external surface and were larger than corresponding voids of the metal-organic framework. The formation of Ag&ndash, Pd alloy or monometallic Ag and Pd depended on the nature of both metal precursors and the impregnation solvent used. Catalytic activity of the AgPd/UiO-66 materials in propylene glycol oxidation was found to be a result of synergistic interaction between the components in AgPd alloyed NPs immobilized in the pore space and on the external surface of UiO-66. The key factor for consistent transformation of propylene glycol into lactic acid was the proximity between redox and acid-base species.

This study reports the differences in toxic action between cadmium sulfide (CdS) and zinc sulfide (ZnS) nanoparticles (NPs) prepared by recently developed xanthate-mediated method. The aquatic toxicity of the synthesized NPs on four marine microalgae species was explored. Growth rate, esterase activity, membrane potential, and morphological changes of microalgae cells were evaluated using flow cytometry and optical microscopy. CdS and ZnS NPs demonstrated similar level of general toxicity and growth-rate inhibition to all used microalgae species, except the red algae P. purpureum. More specifically, CdS NPs caused higher inhibition of growth rate for C. muelleri and P. purpureum, while ZnS NPs were more toxic for A. ussuriensis and H. akashiwo species. Our findings suggest that the sensitivity of different microalgae species to CdS and ZnS NPs depends on the chemical composition of NPs and their ability to interact with the components of microalgal cell-wall. The red microalga was highly resistant to ZnS NPs most likely due to the presence of phycoerythrin proteins in the outer membrane bound Zn2+ cations defending their cells from further toxic influence. The treatment with CdS NPs caused morphological changes and biochemical disorder in all tested microalgae species. The toxicity of CdS NPs is based on their higher photoactivity under visible light irradiation and lower dissociation in water, which allows them to generate more reactive oxygen species and create a higher risk of oxidative stress to aquatic organisms. The results of this study contribute to our understanding of the parameters affecting the aquatic toxicity of semiconductor NPs and provide a basis for further investigations.

In the present study, a mesoporous photocatalyst based on Au–Pd nanoparticles incorporated into g-C3N4 was prepared by a coassembly method using melamine as the carbon and nitrogen source, polyvinyl pyrrolidone as the dispersing agent, and pulse laser ablation in liquid technique for preparing gold nanoparticles and subsequent decoration with Pd nanoparticles. At the final stage, Au–Pd/g-C3N4 nano-photocatalyst was obtained via low-ramping pyrolysis in an argon atmosphere. The activity of the catalyst was related to its structure, which was characterized by high-resolution transmission electron microscopy, field-emission scanning electron microscopy, X-ray photoelectron spectroscopy, energy-dispersive X-ray spectroscopy, and Brunauer–Emmett–Teller analysis. The results demonstrated that the Au–Pd-containing catalyst exhibited superior performance compared to its counterparts containing monometallic nanoparticles. The influence of variables such as reaction temperature, time of irradiation, amount of hydro...

Laser ablation in liquid was used to prepare homogeneous copper–zinc alloy catalysts that exhibited excellent selectivity for C2H4 in CO2 electroreduction, with faradaic efficiency values as high as 33.3% at a potential of −1.1 V (vs reversible hydrogen electrode). The high proximity of Cu and Zn atoms on the surface of the catalyst was found to facilitate both stabilization of the CO* intermediate and its transfer from Zn atoms to their Cu neighbors, where further dimerization and protonation occur to give rise to a large amount of ethylene product. The new homogeneous nanocatalyst, along with the mechanism proposed for its performance, may be very helpful for in-depth understanding of processes related to carbon dioxide electroreduction and conversion.

Mixed oxides of Zn and Sn are of interest for gas sensing and diverse optoelectronic applications, and therefore new approaches to prepare such nanomaterials are anticipated. This study reports, for the first time, on the use of laser ablation in liquid applied to a Sn-Zn alloy and describes obtained products. Core@shell Sn@SnO and ZnO nanoparticles are shown to be produced by millisecond pulsed laser upon ablating eutectic Sn-Zn alloy in water. The as-prepared materials were found to contain surface hydroxide layers which were dehydrated to SnOx and ZnO when higher laser energy fluence was applied or when the products were post-treated at 200C in air. The morphology, shape and size distribution, phase and chemical composition of prepared nanoparticles were studied as a function of laser parameters used during their preparation. Increase in pulse energy was found to result in fabrication of finer particles. It was found that while both metallic Sn and SnOx were presented in the product, zinc was always oxidized to its oxide ZnO. In addition, when properly annealed, the produced nanomaterial demonstrated gas sensing response towards ammonia at room temperature.

Zinc oxide is a cost-efficient and eco-friendly material for solar-to-chemical energy conversion. However, the relatively wide band gap and poor stability restrict its practical applications. Herein, we report on the modification of ZnO nanosheets with a porous atomically thin ZnS overlayer. The as-prepared ZnS/ZnO/ZnS sandwich nanosheets exhibit a reduced band gap (2.72 eV) and yet a slightly elevated conduction band minimum, which remarkably broadens the wavelength range for light absorption and generates electrons with enough reducing capability. At the same time, the newly-prepared sandwich nanosheets possess alternatively exposed ZnS and ZnO surface patches, which attract and accommodate photo-generated holes and electrons, respectively. In addition, the ZnS overlayer catalyzes and accelerates hole-consumption reactions, thus preserving electrons for efficient water splitting. As a result, the ZnS/ZnO/ZnS sandwich nanosheets demonstrate intensive light absorption, fast charge separation, long electron lifetime, and eventually the highest hydrogen production rate reported for oxide catalysts so far. This work proves that passivation with an ultrathin layer is a potent approach for energy-band engineering, and semiconductor sandwich nanostructures are promising for highly efficient water splitting under sunlight.

Understanding the effect of reactive oxygen species (ROS), such as singlet oxygen molecule and atomic oxygen, on polyimide (PI) film properties, such as wettability, morphology, and chemical bonding state, is essential for further development of PI-based surfaces. We investigated the effect of different ROS generated during ultraviolet (UV) and plasma treatment in oxygen gas on surface modification of Kapton PI. Different surface modification techniques, UV and plasma treatment, are known to generate different ROS. In this work, we demonstrate the effect of different ROS on PI surface modification. From the diagnostics of ROS by means of electron spin resonance and optical emission spectroscopy, we confirmed that during UV treatment, excited singlet oxygen molecules are the main ROS, while plasma treatment mainly generated atomic oxygen. The wettability of PI surface treated by UV and plasma resulted in hydrophilic PI surfaces. XPS results show that the wettability of PI samples is mainly determined by their surface O/C ratio. However, chemical bonding states were different: while UV treatment tended to generate C=O bonds, while plasma treatment tended to generate both C―O and C=O bonds. Singlet oxygen molecules are concluded to be the main oxidant during UV treatment, and their main reaction with PI was concluded to be of the addition type, leading to an increase of C=O groups on the surface of PI film. Meanwhile, atomic oxygen species were the main oxidant during plasma treatment, reacting with the PI surface through both etching and addition reaction, resulting in a wider variety of bonds, including both C―O and C=O groups.

Owing to their high extinction coefficient and moderate band gap, cadmium chalcogenides are known as common semiconductors for photoelectric conversion. Nevertheless, no ideal cadmium chalcogenide with proper band structure is available yet for photoelectrochemical hydrogen evolution. In this work, we modified the band structure of CdTe via alloying with Se to achieve a ternary compound (CdSe0.8Te0.2) with n-type conduction, a narrower band gap, and a more negative band position compared to those of CdSe and CdTe. This novel material exhibits strong light absorption over a wider spectrum range and generates more vigorous electrons for hydrogen reduction. As a result, a photoelectrode based on nanoflake arrays of the new material could achieve a photocurrent density 2 times that of its CdSe counterpart, outperforming similar materials previously reported in the literature. Moreover, the quick transfer of holes achieved in the novel material was found to depress photocorrosion processes, which led to improv...

In this paper, we report a new, simple method for the synthesis of CdS and ZnS nanoparticles (NPs) prepared in a basic aqueous medium using metal xanthate as the sulfur source. The structure, morphology, size distribution, optical band gap, and photocatalytic properties of the newly obtained nanomaterials were investigated by UV-Vis spectroscopy, X-ray diffraction, and transmission electron microscopy. The results show that both CdS and ZnS crystallized in cubic phase and formed NPs with average sizes of 7.0 and 4.2 nm for CdS and ZnS, respectively. A blue shift of UV-Vis absorbance band and higher energy band gap values were observed for both materials in comparison with their bulk counterparts, which is in accordance with the quantum confinement effect. The as-prepared nanomaterials were tested in visible-light driven photocatalytic decomposition of methylene blue (MB). After irradiation for 180 min, the degradation rate of MB with a concentration of 8 &times, 10&minus, 6 mol/L mixed with a photocatalyst (CdS or ZnS, both 10 mg in 100 mL solution of MB) was found to be 72% and 61%, respectively. The CdS NPs showed better photocatalytic activity than ZnS, which could be explained by their lower energy band gap and thus the ability to absorb light more efficiently when activated by visible-light irradiation.

Engineering surface structure of catalysts is an efficient way towards high catalytic performance. Here, we report on the synthesis of regular iridium nanospheres (Ir NSs), with abundant atomic steps prepared by a laser ablation technique. Atomic steps, consisting of one-atom level covering the surface of such Ir NSs, were observed by aberration-corrected high-angle annular dark-field scanning transmission electron microscopy (HAADF-STEM). The prepared Ir NSs exhibited remarkably enhanced activity both for oxygen evolution reaction (OER) and hydrogen evolution reaction (HER) in acidic medium. As a bifunctional catalyst for overall water splitting, they achieved a cell voltage of 1.535 V @ 10 mA/cm2, which is much lower than that of Pt/C-Ir/C couple (1.630 V @ 10 mA/cm2).

We demonstrate a multi-purpose plasmonic sensor based on a nanovoid array fabricated via inexpensive and highly-reproducible direct femtosecond laser patterning of thin glass-supported Au films. The proposed nanovoid array exhibits near-IR surface plasmon (SP) resonances, which can be excited under normal incidence and optimised for specific applications by tailoring the array periodicity, as well as the nanovoid geometric shape. The fabricated SP sensor offers competitive sensitivity of &asymp, 1600 nm/RIU at a figure of merit of 12 in bulk refractive index tests, as well as allows for identification of gases and ultra-thin analyte layers, making the sensor particularly useful for common bioassay experiments. Moreover, isolated nanovoids support strong electromagnetic field enhancement at lattice SP resonance wavelength, allowing for label-free molecular identification via surface-enhanced vibration spectroscopy.

Niobium oxide films prepared via anodic oxidation are known to exhibit various colors. These colors are affected by the voltage during anodizing treatment to produce such thick film. The anodic oxidation reaction stops when the applied voltage reaches its saturation value. At this point the film stops growing, its thickness of the internal oxide layer being proportional to the applied voltage. Therefore, this study aims to clarify the relationship between the oxidation state inside the anodized film and its thickness. We also attempted to anodize a polyimide (PI) film, which is a flexible resin material. Because such a PI film is nonconductive, it was sputter-coated with an intermediate layer of niobium before anodization. To enable adhesion to the PI film, the Nb-sputtered film was subjected to surface modification via oxygen plasma treatment. Finally, the Nb-coated PI film was subjected to anodization. Detailed optical comparison was performed between the anodized Nb-coated PI substrate and anodized Nb plate substrate.

The work reports on the use of laser ablation and irradiation in acetone and water to prepare copper and zinc oxide nanoparticles (NPs) as potential components for photovoltaic applications. Optical and morphological properties of the products were studied by absorption spectroscopy and transmission and scanning electron microscopy. The possibility of controlled modification of produced NPs and their characteristics by additional laser irradiation was demonstrated. As demonstration of potential of such laser-generated NPs for photovoltaic applications, heterojunction interface was fabricated by spin-coating of p-CuO and n-ZnO thin films onto indium-tin oxide substrate, after which electrical properties of the as-prepared device were evaluated.

A new approach to fabricate TiNi surfaces combining the advantages of both monolithic and porous materials for implants is used in this work. New materials were obtained by depositing a porous TiNi powder onto monolithic TiNi plates followed by sintering at 1200 °C. Then, further modification of the material surface with a high-current-pulsed electron beam (HCPEB) was carried out. Three materials obtained (one after sintering and two after subsequent beam treatment by 30 pulses with different pulse energy) were studied by XRD, SEM, EDX, surface profilometry, and by means of electrochemical measurements, including OCP and EIS. Structural and compositional changes caused by HCPEB treatment were investigated. Surface properties of the samples during their storage in saline for 10 days were studied and a model experiment with cell growth (MCF-7) was carried out for the unmodified sample with an electron beam to detect cell appearance on different surface locations.

In this study, nanomaterials prepared via laser ablation of tin in water are systematically studied and compared. Tin targets were ablated by both millisecond and nanosecond pulsed lasers, resulting in core@shell product nanostructures with different chemistries and morphologies. Depending on laser fluence, the obtained core@shell nanoparticles had either Sn or SnO cores and SnOx shells with varied surface hydration degree. Optical emission spectra of laser-generated plasmas were taken, giving additional support to nanoparticle formation mechanisms. Finally, gas sensing at room temperature is demonstrated as one of the potential applications for such nanostructures.

It is fascinating and challenging to endow conventional materials with unprecedented properties. For instance, cadmium sulfide (CdS) is an important semiconductor with excellent light response; however, its potential in gas-sensing was underestimated owing to relatively low chemical activity and poor electrical conductivity. Herein, we demonstrate that an ideal architecture, ultrathin nanoflake arrays (NFAs), can improve significantly gas-sensing properties of CdS material. The CdS NFAs are grown directly on the interdigitated electrode to expose large surface area. Their thickness is reduced below the double Debye length of CdS, permitting to achieve a full depletion of carriers. Particularly, the prepared CdS nanoflakes are enclosed with high-energy {0001} facets exposed, which provides more active sites for gas adsorption. Moreover, the NFAs exhibit the light-trapping effect, which further enhances their gas sensitivity. As a result, the as-prepared CdS NFAs demonstrate excellent gas-sensing and light-response properties, thus being capable of dual gas and light detection.

Zinc-air fuel cells (ZAFCs) present a promising energy source with a competing potential with the lithium-ion battery and even with proton-exchange membrane fuel cells (PEMFCs) for applications in next generation electrified transport and energy storage. The regeneration of zinc is essential for developing the next-generation, i.e., electrochemically rechargeable ZAFCs. This review aims to provide a comprehensive view on both theoretical and industrial platforms already built hitherto, with focus on electrode materials, electrode and electrolyte additives, solution chemistry, zinc deposition reaction mechanisms and kinetics, and electrochemical zinc regeneration systems. The related technological challenges and their possible solutions are described and discussed. A summary of important R&D patents published within the recent 10 years is also presented.

Porous ceramic materials of SiC were synthesized from carbon matrices obtained via pyrolysis of natural cork as precursor. We propose a method for the fabrication of complex-shaped porous ceramic hardware consisting of separate parts prepared from natural cork. It is demonstrated that the thickness of the carbon-matrix walls can be increased through their impregnation with Bakelite phenolic glue solution followed by pyrolysis. This decreases the material's porosity and can be used as a way to modify its mechanical and thermal characteristics. Both the carbon matrices (resulted from the pyrolysis step) and the resultant SiC ceramics are shown to be pseudomorphous to the structure of initial cork. Depending on the synthesis temperature, 3C-SiC, 6H-SiC, or a mixture of these polytypes, could be obtained. By varying the mass ratio of initial carbon and silicon components, stoichiometric SiC or SiC:C:Si, SiC:C, and SiC:Si ceramics could be produced. The structure, as well as chemical and phase composition of the prepared materials were studied by means of Raman spectroscopy and scanning electron microscopy.

The development of flexible and low-cost methods of surface functionalization to fight infection at the early stage is an urgent scientific task. Herein, polymerization in low-pressure plasma rich in COOH species and carbodiimide chemistry methods were utilized to immobilize four different therapeutic agents (antibiotic (gentamicin), antimicrobial peptide (indolicidin), anti-adhesive molecules (heparin) and nitroxide radicals (2,2,5,5-tetramethyl-3-carboxyl-pyrrolidine-1-oxyl)) on the surface of nanostructured biocompatible TiCaPCON films to impart antibacterial characteristics. The polymers deposited from COOH-rich plasma showed decent stability in phosphate-buffered saline solution and were successfully used for the immobilization of different therapeutic agents via ionic or covalent bond. The bactericide attachment was proved by FTIR spectroscopy and XPS analysis. All samples with grafted therapeutic agents were hydrophilic with water contact angle values in the range of 26–56°. Bactericide release tests indicated the maximum concentration of therapeutic agents in the case of ionic immobilization. In case of covalent immobilization, fast initial release observed over 24 h was followed by slower leaching in the next 24 h (indolicidin), 48 h (heparin), and 96 h (gentamicin). The pH-sensitive COOH plasma polymer degradation and gentamicin release were demonstrated. The bactericide-linked films showed noticeable reduction of the antibiotic-sensitive E. coli U20 strain and, except indolicidin-immobilized samples, effectively inhibited growth of the antibiotic-resistant E. coli K261 strain at their initial concentration of 104 CFU/mL. The films with nitroxide radicals not only exhibited the highest antibacterial activity against E. coli K261 cells (100% after 8 h), but also prevented the biofilm formation.

Core-shell nanoparticles (NPs) have attracted tremendous attention due to their tunable properties and numerous potential applications. However, preparation of uniform and size-controlled core-shell nanomaterials of ZnO with graphene oxide (GO) is still considered as a challenging task even after years of research. In this work, we report on a facile one-pot organics-free method for preparation of GO-wrapped ZnO NPs. Laser ablation of zinc and carbon targets in water medium at ambient atmosphere resulted in formation of spherical ZnO core and GO shell, respectively. According to Raman active modes, the GO shell was layered and the ZnO core was polycrystalline. Both Raman spectra and X-ray diffraction patterns revealed that formation of layered GO increased stress inside the ZnO core. Surface layers reduced the density of defects and disorders in the ZnO crystal lattice and enhanced the phonon lifetime. Also, the minimal interfacial disorder between the layered GO and ZnO core resulted in continuous formation of a GO layer. Thus, laser ablation in liquid is demonstrated to provide stable and uniform core-shell GO@ZnO NPs with controlled GO layer that can find applications in biomedical and sensing fields.

We report on high-quality infrared (IR)-resonant plasmonic nanoantenna arrays fabricated on a thin gold film by tightly focused femtosecond (fs) laser pulses coming at submegahertz repetition rates at a printing rate of 10 million elements per second. To achieve this, the laser pulses were spatially multiplexed by fused silica diffractive optical elements into 51 identical submicrometer-sized laser spots arranged into a linear array at periodicity down to 1 μm. The demonstrated high-throughput nanopatterning modality indicates fs laser maskless microablation as an emerging robust, flexible, and competitive lithographic tool for advanced fabrication of IR-range plasmonic sensors for environmental sensing, chemosensing, and biosensing.

Here, we demonstrate a simple direct maskless laser-based approach for fabrication of back-reflector-coupled plasmonic nanorings arrays. The approach is based on delicate ablation of an upper metal film of a metal-insulator-metal (MIM) sandwich with donut-shaped laser pulses followed by argon ion-beam polishing. After being excited with a radially polarized beam, the as-prepared MIM configuration of the nanorings permitted to realize efficient nanofocusing of constructively interfering plasmonic waves excited in the gap area between the nanoring and back-reflector mirror. For optimized geometric parameters of such MIM structure, substantial enhancement of the electromagnetic near-fields at the center of the ring within a single focal spot with the size of 0.37$\lambda^{2}$ can be achieved, which is confirmed by Finite Difference Time Domain (FDTD) calculations, as well as by detection of enhanced PL signal from adsorbed organic dye molecules. The simple large-scale and cost-efficient fabrication procedure used, along with relatively good tolerance to excitation beam misalignment, make the proposed structures promising for realization of various nanophotonic and biosensing platforms that utilize cylindrical vector beam as a pump source., Comment: 7 pages, 3 figures

Nanophotonics based on resonant nanostructures and metasurfaces made of halide perovskites have become a prospective direction for efficient light manipulation at the subwavelength scale in advanced photonic designs. One of the main challenges in this field is the lack of large-scale low-cost technique for subwavelength perovskite structures fabrication preserving highly efficient luminescence. Here, unique properties of halide perovskites addressed to their extremely low thermal conductivity (lower than that of silica glass) and high defect tolerance to apply projection femtosecond laser lithography for nanofabrication with precise spatial control in all three dimensions preserving the material luminescence efficiency are employed. Namely, with CH3 NH3 PbI3 perovskite highly ordered nanoholes and nanostripes of width as small as 250 nm, metasurfaces with periods less than 400 nm, and nanowire lasers as thin as 500 nm, corresponding to the state-of-the-art in multistage expensive lithographical methods are created. Remarkable performance of the developed approach allows to demonstrate a number of advanced optical applications, including morphology-controlled photoluminescence yield, structural coloring, optical- information encryption, and lasing.

This article reports on fabrication of activated TiO2 and gold decorated TiO2 prepared by irradiation with millisecond laser and on their gas sensing properties. Commercially available anatase TiO2 was used as starting material whose nanoparticles were modified and decorated upon irradiating its water suspension by pulsed laser. Formation of Au nanoparticles was achieved by laser-induced reduction of Au(III) ions, followed by their deposition onto TiO2 nanoparticle surface. In order to evaluate the effect of gold concentration in Au@TiO2 nanocomposites on their sensing properties, two gold-containing samples with 1 and 5 wt% of Au were prepared. All nanomaterials were characterized by XRD, XPS and SEM methods and then tested as gas sensing devices towards a number of volatile compounds. XPS analysis revealed formation of oxygen vacancies and Ti3+ ions on the TiO2 surface upon laser irradiation, while the latter defects disappeared after decoration with gold. Depending on the degree of Au loading, the samples demonstrated selectivity towards ammonia, acetaldehyde or benzene.

Carbon fiber felt (CFF) is considered as a stable carbonaceous support for different applications such as absorbents and catalysts. Herein, a novel method for preparation of Au-Pd/CFF@TiO2 catalysts is presented. Structure, morphology, and performance of the novel nano-catalyst were characterized during different stages of their fabrication by means of structural, chemical and optical techniques. The results demonstrated that, compared with the other products, the Au-Pd/CFF@TiO2 composite pyrolyzed at 450 °C had the highest thermal and mechanical stability, as well as better textural features. It showed good catalytic activity in oxidation of benzene-to-phenol by hydrogen peroxide (25%) as eco-friendly oxidant under mild thermal conditions. The influence of different parameters on the oxidation process, such as reaction temperature, amounts of catalyst, oxidant/substrate molar ratio and condensation temperature, was investigated to optimize the catalyst. At the optimum set of conditions, the Au-Pd/CFF@TiO2-450 showed the values of yield and selectivity for phenol as the main product as high as 46% and 100%, respectively. The catalyst maintained its activity after eight cycles and thus looks very promising for direct conversion of benzene to phenol under mild conditions.

We developed a simple and efficient process, laser heating of nickel powder in ethanol, to produce carbon-encapsulated nickel microspheres. Long-pulse-width laser heated nickel powder suspended in pure ethanol into liquid droplets. In turn, the latter droplets became sphere-like, pyrolyzed surrounding ethanol and dissolved the produced carbon atoms. Because of their lower solubility in solid nickel, excess carbon atoms were then expelled from the metal core after solidification, thus forming graphite-like shells on the laser-modified Ni spheres. Hence, after pyrolysis the transformation of carbon was found to follow the dissolution-precipitation mechanism. The produced carbon-encapsulated nickel microspheres exhibited higher oxidation resistance compared with the initial nickel powder, while keeping their magnetic properties essentially unchanged.

Highly sensitive and selective detection of volatile organic compounds (VOCs) with fast response time is imperative based on safety requirements, yet often remains a challenge. Herein, we propose an effective solution, preparing a novel gas sensor comprised of amorphous nanoflake arrays (a-NFAs) with specific surface groups. The sensor was produced via an extremely simple process in which a-NFAs of CdO were deposited directly onto an interdigital electrode immersed in a chemical bath under ambient conditions. Upon exposure to a widely used VOC, diethyl ether (DEE), the sensor exhibits excellent performance, more specifically, the quickest response, lowest detection limit and highest selectivity ever reported for DEE as a target gas. The superior gas-sensing properties of the prepared a-NFAs are found to arise from their open trumpet-shaped morphology, defect-rich amorphous nature, and surface CO groups.

ZnO nanomaterials with controlled size, shape and surface chemistry are required for applications in diverse areas, such as optoelectronics, photocatalysis, biomedicine and so on. Here, we report on ZnO nanostructures with rod-like and spherical shapes prepared via laser ablation in liquid using a laser with millisecond-long pulses. By changing laser parameters (such as pulse width and peak power), the size or aspect ratio of such nanostructures could be tuned. The surface chemistry and defects of the products were also strongly affected by applied laser conditions. The preparation of different structures is explained by the intense heating of liquid media caused by millisecond-long pulses and secondary irradiation of already-formed nanostructures.

Molecular precursors are suitable starting compounds for preparation of semiconductor nanoparticles (NPs), which allow for control of atomic ratio, composition, monodispersity, and particle size of nanoscaled metal sulfides/oxides. In the present study, we carried out a one-pot synthesis of ZnS NPs in aqueous triethanolamine medium at room temperature, from molecular precursor zinc xanthate as a source of both Zn2+ and S2&minus, ions. Furthermore, we compared the products obtained from zinc ethylxanthate (Zn(C2H5OCS2)2) and zinc amylxanthate (Zn(C5H11OCS2)2). The as-prepared ZnS NPs were found to crystallize in cubic phase, which usually forms at low temperatures, with the dimension dependent on the xanthate precursor used. The long carbon-chain xanthate Zn(C5H11OCS2)2 gave spherically shaped NPs with an average diameter of 19 nm, while the NPs that originated from zinc ethylxanthate had a mean size of ~26 nm. Both nanomaterials had surface sulfur vacancies that extended their absorption spectra toward the visible region and reduced the band gap. This allowed both materials to demonstrate photocatalytic performance under visible-light irradiation. Photodegradation of methylene blue over newly prepared ZnS NPs was tested under visible light, demonstrating efficiency of 50%&ndash, 60% after 180 min.

Detection of ammonia by carbon nanotubes is an extensively studied area where tremendous progress was achieved so far in their sensing performance. In this paper, we focused on carbon nanotube network sensors of NH 3 aiming to develop better understanding of their gas detection behavior and improved sensing response. Our experiments showed improved sensing performance for single-walled carbon nanotubes of (6,5) chirality ultrasonically treated at high power and then forming bundled nanotube network upon thermal annealing. Two chemiresistive sensing pathways were observed for such networks resulting in increased and decreased resistance in presence of different ammonia concentrations from 10 2 to 10 4 ppm. This multidirectional chemiresistive response was comprehensively explained via various phenomena, such as partial and full neutralization of p-type conductivity of the nanotubes, change of the Schottky barrier, and dipoles at the interface between nanotubes and gold electrodes. The proposed sensing mechanisms are believed to provide strong support for further development of ammonia sensors with optimized performance.

Halide perovskites are a family of materials with a high potential for realization of microlasers, due to their high luminescence quantum yield and broad spectral tunability. Here we demonstrate a single-step process for lasing microdisk fabrication from a thin film of methylammonium lead iodide (MAPbI3) perovskite through its patterning with tightly focused femtosecond (fs) laser pulses. By using kHz-scale pulse bursts destructive overheating of the material was suppressed. Perovskite microdisks fabricated under such optimized conditions showed stable lasing upon pumping with fs-laser both at lower (50kHz) and higher (80MHz) repetition rates and operation temperatures of 300K and 6K, respectively.

Biomorphic carbon matrices (BCMs) were produced by pyrolysis from wood species of different forest and garden trees, after which the as-prepared BCMs were converted to SiC ceramics through their impregnation with liquid silicon and further heat-treatment. Both types of obtained samples were studied by scanning electron microscopy (SEM), Raman scattering (RS), and electron spin resonance (ESR) methods. The SEM data reveal that all BCM samples contain large (10–50 μm) and small (1–5 μm) micro-pores with surface densities ∼109 m−2 and 1011 m−2, respectively. Analysis of RS allowed to estimate carbon cluster sizes of about 5–11 nm depending on the sample type. The study of the electronic structure using ESR spectroscopy is carried out for BCM and SiC ceramics samples. Using theoretical analysis of the ESR spectra, it was found that spin resonance in BCMs is due to the contribution of three spin systems: free electron spins, “pseudo-free” electron spins from the tail of density states below the conduction band, and localized spins at dangling carbon bonds (DCBs). Their contributions depend on the ratio of different structural phases such as sp2-hybridized graphite-like carbon network and amorphous carbon phase. For most BCM samples, the large ESR line width is dramatically narrowed when samples are pumped out due to the exclusion of the broadening effect of molecular oxygen. The transformation of BCM into SiC by impregnation with liquid silicon can be clearly traced in the Raman spectra and in the ESR spectra. It is established that the electronic properties of synthesized SiC ceramics are due to the presence of residual graphite-like carbon nanoclusters.Biomorphic carbon matrices (BCMs) were produced by pyrolysis from wood species of different forest and garden trees, after which the as-prepared BCMs were converted to SiC ceramics through their impregnation with liquid silicon and further heat-treatment. Both types of obtained samples were studied by scanning electron microscopy (SEM), Raman scattering (RS), and electron spin resonance (ESR) methods. The SEM data reveal that all BCM samples contain large (10–50 μm) and small (1–5 μm) micro-pores with surface densities ∼109 m−2 and 1011 m−2, respectively. Analysis of RS allowed to estimate carbon cluster sizes of about 5–11 nm depending on the sample type. The study of the electronic structure using ESR spectroscopy is carried out for BCM and SiC ceramics samples. Using theoretical analysis of the ESR spectra, it was found that spin resonance in BCMs is due to the contribution of three spin systems: free electron spins, “pseudo-free” electron spins from the tail of density states below the conduction band...

A new avenue for analyzing Ru deposition solution and depositing uniform nano-sized Ru structures on Pt substrates with enhanced reproducibility is shown in this work. UV–vis spectrophotometry in conjunction with electrochemical analysis shows that the deposition has a 5-day stability period between 2 and 6 days of its aging. During this stability period, UV–vis spectra showed that Ru(III) and Ru(IV) complexes of [Ru(H2O)Cl5]2−, [RuH2O(OH)2Cl3]− and Ru-sulfates are in equilibrium. Electrochemical and in situ STM analysis also revealed that Ru nano-structures can be reproducibly deposited onto Pt using a diffusion control potential range of −0.47 to −0.32 V/MSE found in this work. The presence of both metallic Ru and Ru oxides within the deposit from XPS analysis suggests that the different Ru complexes present in the aged solution are involved in multiple parallel reduction processes for Ru deposition.

In the present study, we demonstrate efficient detection of volatile organic vapors with improved sensitivity, exploiting the localized surface plasmon resonance of indium nanograins in the UV range (UV-LSPR). The sensitivity of deep-UV-LSPR measurements toward ethanol was observed to be 0.004 nm/ppm, which is 10 times higher than that of a previously reported visible-LSPR device based on Ag nanoprisms [Sensors 11, 8643 (2011)]. Although practical issues such as improving detection limits are still remaining, the results of the present study suggest that the new approach based on UV-LSPR may open new avenues to the detection of organic molecules in solid, liquid, and gas phases using plasmonic sensors.