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Protective ceramic coatings are frequently the most common solutions for problems like corrosion and wear. Polymer derived ceramics technology is suitable for the preparation of ceramic coatings by pyrolysis in a furnace but requires high temperatures for the ceramization. To overcome this restriction a Nd:YVO 4 laser (λ = 1064 nm) as energy source was used to process a novel ceramic coating system composed of an organosilazane with zirconia and alumina particles specially to protect magnesium. The resulting dense ceramic coating with a thickness up to 20 µm exhibits very good adhesion (25.9 ± 2.7 MPa) to the magnesium substrate, exceptionally high hardness (19.79 ± 1.90 GPa), an outstanding thermal shock stability but also a low coefficient of friction (0.21 ± 0.02) and a very good wear protection towards a SiC counter body. Furthermore, the coating protects the magnesium substrate effectively against corrosion (5 wt% aqueous NaCl solution). [ABSTRACT FROM AUTHOR]

TiO2 nanoparticles (NPs) doped with W (W:TiO2), double-doped with W and V (W&V:TiO2), and loaded with noble metals (W:TiO2 @Pt/Pd/Ag and W&V:TiO2@Pt/Pd/Ag) were synthesized by laser pyrolysis followed by chemical impregnation and reduction. Due to its exceptional properties, TiO2 is considered a key material being used in a wide range of applications. To improve its detection activity, the increase in the specific surface of the material, and the presence of defects in its structure play a decisive role. Doped and double-doped TiO2 nanoparticles with dimensions in the range of 25–30 nm presented a mixture of phases corresponding to titania, with the anatase phase accounting for the majority (95%). By loading these nanoparticles with small particles of noble metals, a significant increase in the specific surface area by three or even five times the original values was achieved. Sensitive thin films for surface acoustic wave (SAW) sensors were made with the NPs, embedded in polyethyleneimine (PEI) polymer and deposited by spin-coating. Each sensor was tested at CH4 concentrations between 0.4 and 2%, at room temperature, and the best results were obtained by the sensor with NPs doped with V and decorated with Pd, with a limit of detection (LOD) of 17 ppm, due to the strong catalytic effect of Pd. [ABSTRACT FROM AUTHOR]

The polymer precursor derived ceramics route is one of the important ways for the preparation of ceramics, and pyrolysis is absolutely necessary in the process. The traditional thermal pyrolysis suffers from slow heating/cooling rate, long processing time, and high energy consumption. In recent years, new technologies, including laser pyrolysis, microwave treatment, and discharge plasma sintering, have attracted the attention in the researchers due to the advantages of fast heating/cooling rate and low energy consumption. This paper summarizes the research progress in rapid pyrolysis in PDCs. The advantages of the new technologies in the preparation of high-performance ceramics are also discussed. [ABSTRACT FROM AUTHOR]

To solve such global problems as climate stabilization and reducing greenhouse gas luminescences requires an integrated approach, including a strategic analysis of the problem and the development of criteria for selecting proposed solutions, a natural scientific research on the possibilities and ways to implement the assigned tasks, as well as an economic justification for the feasibility of implementing the developed measures. The present publication is an attempt to apply this approach to the problem of hydrogen energy via proposing the production of hydrogen by pyrolysis of natural gas in laser plasma as one of the ways to its solution. Therewith, the main attention is focused on the chemical processes that occur in laser plasma, as well as on the nature of the transformations that occur in the solid pyrolysis product. [ABSTRACT FROM AUTHOR]

Efficient and durable electrocatalysts are instrumental in enabling next‐generation fuel cell technologies. At present, expensive precious metals are used as state‐of‐the‐art catalysts. In this report, cost‐effective nanosized tantalum‐based alternatives are synthesized for the first time via a green and scalable laser pyrolysis method as bifunctional catalysts for direct peroxide–peroxide fuel cells. This rapid laser pyrolysis strategy allows for the production of nanoparticles at a laboratory scale of grams per hour, compatible with a detailed exploration of the functional properties of as‐synthesized nanoparticles. By varying the precursor ratio between ammonia and tantalum ethanolate, five tantalum‐based nanomaterials (TaNOC) are prepared with crystalline phases of Ta2O5, Ta4N5, Ta3N5, and TaN in tunable ratios. Electrochemical studies in neutral and alkaline conditions demonstrate that Ta4N5 is the active component for both H2O2 oxidation and reduction. Kinetic isotope effect studies show that protons are involved at or before the rate‐determining step. Long‐term stability studies indicate that Ta3N5 grants surfactant‐free TaNOC‐enhanced longevity during electrocatalytic operations. Taken together, bifunctional TaNOC can act as active and robust electrocatalysts for H2O2 reduction and oxidation. Laser pyrolysis is envisioned to produce refractory metal nanomaterials with boosted corrosion resistance for energy catalysis. [ABSTRACT FROM AUTHOR]

Abstract As a vital chemical, ammonia (NH3) plays an irreplaceable role in many fields such as chemical synthesis and energy storage. Green renewable biomass can be converted into biofuels, but its nitrogen resources are underused throughout. Laser‐driven pyrolysis is envisaged to debuts as a bridge to connect them to realize the direct conversion from nitrogen‐rich biomass into ammonia. The pulsed laser‐induced local‐transient thermal effect recognized the biological nitrogen resources conversion, such as cheap and plentiful yeasts, to small gaseous molecules and achieved spectacular ammonia production rate up to 260.4 mg/h, an order of magnitude higher performance than thermochemical ammonia synthesis. Simultaneously, the tiny hot point generated by a low‐energy laser (20 W) guarantees the whole ammonia synthesis reaction system is in a mild environment of low temperature and normal pressure. Additionally, the remaining solid residue after laser‐driven pyrolysis also can be further exploited as a highly active catalyst for electrocatalytic nitrate reduction reaction (NIRR).

TiO2 nanoparticles (NPs) doped with W (W:TiO2), double-doped with W and V (W&V:TiO2), and loaded with noble metals (W:TiO2 @Pt/Pd/Ag and W&V:TiO2@Pt/Pd/Ag) were synthesized by laser pyrolysis followed by chemical impregnation and reduction. Due to its exceptional properties, TiO2 is considered a key material being used in a wide range of applications. To improve its detection activity, the increase in the specific surface of the material, and the presence of defects in its structure play a decisive role. Doped and double-doped TiO2 nanoparticles with dimensions in the range of 25–30 nm presented a mixture of phases corresponding to titania, with the anatase phase accounting for the majority (95%). By loading these nanoparticles with small particles of noble metals, a significant increase in the specific surface area by three or even five times the original values was achieved. Sensitive thin films for surface acoustic wave (SAW) sensors were made with the NPs, embedded in polyethyleneimine (PEI) polymer and deposited by spin-coating. Each sensor was tested at CH4 concentrations between 0.4 and 2%, at room temperature, and the best results were obtained by the sensor with NPs doped with V and decorated with Pd, with a limit of detection (LOD) of 17 ppm, due to the strong catalytic effect of Pd.

Abstract Efficient and durable electrocatalysts are instrumental in enabling next‐generation fuel cell technologies. At present, expensive precious metals are used as state‐of‐the‐art catalysts. In this report, cost‐effective nanosized tantalum‐based alternatives are synthesized for the first time via a green and scalable laser pyrolysis method as bifunctional catalysts for direct peroxide–peroxide fuel cells. This rapid laser pyrolysis strategy allows for the production of nanoparticles at a laboratory scale of grams per hour, compatible with a detailed exploration of the functional properties of as‐synthesized nanoparticles. By varying the precursor ratio between ammonia and tantalum ethanolate, five tantalum‐based nanomaterials (TaNOC) are prepared with crystalline phases of Ta2O5, Ta4N5, Ta3N5, and TaN in tunable ratios. Electrochemical studies in neutral and alkaline conditions demonstrate that Ta4N5 is the active component for both H2O2 oxidation and reduction. Kinetic isotope effect studies show that protons are involved at or before the rate‐determining step. Long‐term stability studies indicate that Ta3N5 grants surfactant‐free TaNOC‐enhanced longevity during electrocatalytic operations. Taken together, bifunctional TaNOC can act as active and robust electrocatalysts for H2O2 reduction and oxidation. Laser pyrolysis is envisioned to produce refractory metal nanomaterials with boosted corrosion resistance for energy catalysis.

The purpose of this study was to investigate the synthesis of iron oxide nanoparticles under two different conditions, namely high and low gas flow rates, using laser pyrolysis and to examine the influence of laser power. The attained nanoparticles have been characterised regarding their stability and hydrodynamic dimensions by dispersive light scattering analysis (DLS), structure–X-ray diffraction (XRD), elemental composition–energy-dispersive X-ray spectroscopy (EDS) and X-ray photoelectron spectroscopy (XPS), and morpho-structural characterisation achieved by transmission electron microscopy (TEM) and selected-area electron diffraction (SAED). For a better understanding of the laser power influence, the residence time was also calculated. [ABSTRACT FROM AUTHOR]

Flexible patterned metal halide perovskites (MHPs) are promising to improve the perovskite‐based optoelectronic devices for applications in healthcare monitoring, flexible displays, solar cells, etc. However, their poor environmental stability and device robustness are the main obstacles for commercialization. Herein, a laser pyrolysis assisted process is developed to fabricate flexible patterned CsPbBr3 structures with high stability and flexibility. A CO2 laser is applied to micromachine the designed patterns on the flexible polydimethylsiloxane (PDMS) substrates by inducing the pyrolysis of PDMS. The CsPbBr3 quantum dots (QDs) solution is precisely filled into the patterned PDMS substrates, and subsequently sealed by another layer of PDMS on the top. To ensure the surface smoothness of the patterned PDMS for CsPbBr3 QDs embedment, the mechanism of the laser pyrolysis process is investigated by characterizing the PDMS pyrolysis products obtained at different laser energy densities. To demonstrate the high stability of the fabricated flexible patterned CsPbBr3 structures, the photoluminescent (PL) spectra of the samples are monitored for 60 days both in air and in the water. The flexibility of the fabricated structures is estimated by monitoring their PL emission under applied tension and bending. These flexible patterned CsPbBr3 structures are promising for applications in flexible optical/optoelectronic devices. [ABSTRACT FROM AUTHOR]

TiO2 nanoparticles were synthesized by laser pyrolysis from TiCl4 vapor in air in the presence of ethylene as sensitizer at different working pressures (250–850 mbar) with and without further calcination at 450 °C. The obtained powders were analyzed by energy-dispersive X-ray spectroscopy, X-ray photoelectron spectroscopy, X-ray diffractometry, and transmission electron microscopy. Also, specific surface area and photoluminescence with optical absorbance were evaluated. By varying the synthesis parameters (especially the working pressure), different TiO2 nanopowders were obtained, whose photodegradation properties were tested compared to a commercial Degussa P25 sample. Two series of samples were obtained. Series “a” includes thermally treated TiO2 nanoparticles (to remove impurities) that have different proportions of the anatase phase (41.12–90.74%) mixed with rutile and small crystallite sizes of 11–22 nm. Series “b” series represents nanoparticles with high purity, which did not require thermal treatment after synthesis (ca. 1 atom % of impurities). These nanoparticles show an increased anatase phase content (77.33–87.42%) and crystallite sizes of 23–45 nm. The TEM images showed that in both series small crystallites form spheroidal nanoparticles with dimensions of 40–80 nm, whose number increases with increasing the working pressure. The photocatalytic properties have been investigated regarding the photodegradation of ethanol vapors in Ar with 0.3% O2 using P25 powder as reference under simulated solar light. During the irradiation H2 gas production has been detected for the samples from series “b”, whereas the CO2 evolution was observed for all samples from series “a”.

The structural and magnetic properties of iron oxide nanoparticles (NPs) synthesized by laser pyrolysis, as well as their chitosan-stabilized aqueous suspensions were studied in regards to the ratio between O2 and Ar. During the synthesis, the flow of Fe(CO)5 precursor vapors and C2H4 sensitizer molecules was kept constant, while the ratio between O2 and Ar in the reactive mixture was increased (1:4, 1:2, 1:1, and 2:1). The formation of small particles (under 4 nm in size) was observed at lower O2 concentrations, whereas their mean crystallite size increased to ∼14 nm for those formed from the richest O2 content, which also induced the formation of particles with the highest magnetization saturation (101.4 emu/g). Maghemite and/or magnetite phases were identified as the main components in all samples, while a small amount of α iron/iron carbides presence was detected with the exception of sample obtained at 1:1 O2 to Ar ratio. The formation of these minor phases reveals the interplay between oxidative and reductive processes which depend on O2 content and C2H4 reactivity at different temperatures. After chitosan loading, all aqueous suspensions presented excellent stability (zeta potential values over 76 mV). Moreover, the samples stabilized using low polymer concentration (0.05 g/l) displayed relatively low hydrodynamic sizes (110–125 nm).

Laser pyrolysis, an aerosol nanosynthesis technique, uses a 10.6 μm CO2 laser to rapidly heat precursors to induce decomposition and particle nucleation. A photosensitizing agent, usually SF6, absorbs the laser beam and transfers energy to the precursors. Here, we exploit the presence of SF6 in the system and use it as a safe source of fluorine to synthesize NaYF4 nanocrystals in a single-step process. NaYF4 is an excellent host for rare-earth ions to create upconverting nanocrystals (UCNCs) that absorb infrared photons and emit at shorter wavelength. We thus dope the NaYF4 nanocrystals during synthesis with ytterbium as a sensitizer and erbium, thulium, or holmium as an upconversion emitter. Each emitter produces upconversion emission at specific wavelengths in the visible spectral range after near-infrared light (∼980 nm peaked emission from laser diode) is absorbed by ytterbium followed by energy transfer to emitter. We then show that calcining these materials, in a simple second step, dramatically increases upconversion emission intensity. Finally, we optimize the laser pyrolysis process and postsynthesis calcination to produce the most intense emission at each emission color. We also show that these laser-synthesized UCNCs can be dispersed in a broad range of solvents and retain their visible upconversion emission. This dispersibility could be particularly valuable in creating inks for printing in anticounterfeiting applications. Proof-of-concept use of the synthesized UCNC for anticounterfeiting applications was demonstrated by drop-casting a dispersion of UCNC in stencils on paper, to create various luminescent patterns that were visible under irradiation by a 980 nm laser diode. Overall, this study demonstrates a promising vapor-phase route to rapid, single-step, continuous synthesis of lanthanide-doped fluoride nanomaterials for anticounterfeiting and related applications. [ABSTRACT FROM AUTHOR]

This short communication reports on the facile and scalable synthesis and characterization of molybdenum carbides/carbon nanocomposites prepared by laser pyrolysis in a one-step process. Water and commercial molybdenum oxide were used as low-cost environmentally friendly precursors. The nanocomposites are mainly composed of two types of carbides with different apparent crystallite sizes, 21 ± 1 nm and 9 ± 1 nm for Mo2C and MoC 1 − x , respectively. Thanks to a simple annealing at 500 °C under argon, it was possible to increase the specific surface area around 50 m2/g without changing the morphology of the nanocomposite. [ABSTRACT FROM AUTHOR]

Laser-assisted pyrolysis of aerosols containing phthalocyanine and pyridine yields the direct formation of Fe single atoms dispersed in nitrogen-doped carbon matrixes that can be successfully applied to the oxygen reduction reaction. [Display omitted] • Fe-single atoms dispersed on a N-doped C network are obtained by laser pyrolysis. • Nebulization of phthalocyanines and pyridine provides an excellent precursor for SACs generation. • Thermal activation post-treatments improve the electrochemical response of Fe-N/C catalysts. • These catalysts display high ORR activity in acidic and alkaline electrolytes. Single-Atom Catalysts (SACs) have emerged as the ultimate solutions in challenging systems bridging the gap between homogeneous and heterogeneous catalysts. However, feasible synthesis methods are necessary to stabilize single metal atoms, increase catalyst loadings and scale up the synthesis. Due to its sluggish kinetics, the oxygen reduction reaction (ORR) is the main source of irreversibility in proton exchange membrane fuel cells (PEMFC). The most promising candidates to replace Pt-based catalysts for the ORR in fuel cells are the so-called Fe-N/C catalysts. These catalysts display high ORR activity in acidic and alkaline electrolytes. In this work, we propose a laser-driven pyrolysis approach to generate Fe-N/C SACs that involves decomposition of aerosolized iron-phthalocyanines. The resulting catalyst displays ORR activity in acidic and alkaline electrolytes, with competitive half-potential and kinetic current density values in comparison with state-of-the-art electrocatalysts. [ABSTRACT FROM AUTHOR]

Aluminum and their alloys are particularly suitable for structural components due to their high specific strength and stiffness. However, the low surface hardness and wear resistance limits the lifetime and the use of aluminum. To increase the surface hardness, ceramic-based coatings are frequently the most suitable solutions. A suitable method for the preparation of ceramic coating is the precursor technology. Nevertheless, the required high temperature for the ceramization of the precursor-based coatings in a furnace limits this approach to high temperature-resistant substrates. Laser radiation as a heat source for the pyrolysis of the preceramic polymer is an approach to overcome this restriction. In this paper, we report on a coating system for an aluminum substrate, consisting of a polysilazane (Durazane 2250) bond-coat and a hard top-coat composed of an organosilazane (Durazane 1800) with tetragonal ZrO 2 and aluminum fillers pyrolyzed using Nd:YVO 4 laser. The bond-coat was applied by dip-coating and thermally cross-linked at 150 °C. Afterwards, the top-coat was applied by spraying. The coatings were subsequently ceramized by using laser radiation. Therefore, the laser parameters were adjusted with regard to the low-melting aluminum substrate. The laser irradiation led to pyrolysis of the silazane and to a predominantly dendritic solidification structure, indicating complete melting of the used fillers. Despite the high temperatures within the coating, thermally-activated processes in the aluminum substrate as a result of laser irradiation could be excluded by determining the tensile strength and Young's modulus both before and after laser irradiation. The laser-treated coatings exhibited good adhesion to the substrate. Even under bending load, the coating showed good adhesion and no spalling occurred. Finally, hardness was investigated and compared with coatings of conventional manufacturing processes. These investigations showed that the coatings exhibited very high hardness and are therefore suitable for wear protection. [ABSTRACT FROM AUTHOR]

Protective ceramic‐based coatings are frequently the most suitable solutions for problems like corrosion and wear. It has been shown that the precursor technology is suitable for the preparation of ceramic coatings by pyrolysis in a furnace. However, the required high temperature for the preparation of the ceramic coatings limits this approach to high temperature‐resistant substrates. A very innovative approach to overcome this restriction is the use of laser radiation as a thermal source for the pyrolysis of the preceramic polymer. In this paper, we report on a coating system, for steel substrates, consisting of a polysilazane (Durazane 2250) bond coat and a hard and dense top‐coat composed of an organosilazane (Durazane 1800) with tetragonal ZrO2 particles and aluminum flakes as fillers pyrolyzed using Nd:YVO4 laser. The aluminum fillers led to a significant increase in absorption of the laser energy leading to the formation of a dense coating with a thickness up to 20 μm and a mainly cellular/columnar‐dendritic microstructure. The microstructure, mechanical, and tribological behaviors of these composite coatings are reported and compared to those of laser pyrolyzed glass/ZrO2‐filled polysilazane‐based coatings reported in the literature. [ABSTRACT FROM AUTHOR]

Magnesium oxide nanoparticles were deposited by laser pyrolysis process. Three types of lasers were employed CW CO2, Q-switched Nd-YAG (short pulses) and long pulses Nd-YAG lasers. The size and density of nanoparticles vary with laser energy, power, pulse duration and the scanning speed of the laser. In this method, MgO nanoparticles were deposited by a laser beam on a quartz substrate from aqueous solution of magnesium nitrate. AFM images reveal formation of small nanoparticle size of 24.5 nm with surface roughness 6.97nm by Q-switched Nd-YAG laser (10 ns) when the energy was 1J. While for CO2 laser, the smallest size was 18.8 nm at 0.4mm/s scanning speed with surface roughness 5.21nm at the same scanning speed. Moreover, long Nd-YAG pulses laser produces relatively larger average size of 37.5nm at 0.8ms pulse duration. The absorption spectra from UV-Visible spectroscopy were also conducted. The best absorption intensity was obtained at a wavelength ranging between 420-430 nm for both lasers. Finally, Thermal analysis using COMSOL Multiphysics software for the deposition process reveals that maximum temperature about 440Kfor Q-Switched Nd-YAG laser at 1J laser energy. While for RF CO2 laser, the maximum temperature obtained at 0.4mm/s scanning speed is 850K.This work provides a good knowledge for the deposition of nanoparticles using laser beams.

The preparation of graphene foams via laser pyrolysis of polyimides has gained success due to its ease and speed of processing. Established applications of laser-induced graphene (LIG) involve micro-supercapacitors, batteries, sensors, and water treatment. However, to the best of our knowledge, only a few studies have focused on potential applications of LIG in proton-exchange membrane fuel cells (PEM-FCs). In this study, we demonstrate that LIG obtained from SPEEK films (LIG-S) presents all the key features required of a PEM-FC electrode. Moreover, electrochemical tests in rotating disk and half-cell setups highlight the intrinsic catalytic activity of LIG towards the oxygen reduction reaction. This activity is attributed to structural defects in the LIG lattice and sulfur doping incorporated from the SPEEK precursor, and it may lower the catalyst loading required to reach competitive cell performance.

This paper presents a critical review of laser pyrolysis. Although this technology is almost 60 years old, in literature many researchers, both from academia and industry, are still developing and improving it. On the contrary industrial applications are struggling to take off, if not in very restricted areas, although the technology has undoubted advantages that justify future development. The aim of this work consists in analysing a representative pool of scientific papers (230) and patents (121), from the last 20 years, to have an overview about the evolution of the method and try to understand the efforts spent to improve this technology effectively in academia and in industry. This study is important to provide a complete review about the argument, still missing in the literature. The objective is to provide an overview sufficiently broad and representative in the sources and to capture all the main ways in which laser pyrolysis has been used and with what distribution. The main focuses of the study are the analyses of the functions carried out by laser technologies, the application fields, and the types of used laser (i.e. models, power and fluence). Among the main results, the study showed that the main use of laser pyrolysis is to produce nanoparticles and coatings, the main materials worked by laser pyrolysis are silicon and carbon dioxide and the main searched properties in the products of laser pyrolysis are catalysts activity and electrical conductivity. CO2 lasers are the most used and the have high versatility compared to others. In conclusion, the study showed that laser pyrolysis is a consolidated technology within its main application fields (nanoparticles and coatings) for several years. Within this context, the technology has been developed on very different sizes and processes, obtaining a very wide range of results. Finally, these results may also have stimulated new areas of experimentation that emerged mainly in recent years and which concern biomedical applications, additive manufacturing, and waste disposal. [ABSTRACT FROM AUTHOR]

Proton exchange membrane fuel cells (PEMFCs) are operated in a range of different environments including near-dry operating conditions. When a PEMFC operates under low relative humidity (RH) conditions, performance degradation rapidly occurs because of the decreased ionic conductivity of dehydrated membrane electrode assemblies (MEAs). As such, securing additional water inside the MEA is important for achieving a high-performance PEMFC under low RH operating conditions. Herein, amorphous carbon-encapsulated carbon nano-onions (AC-CNOs) were prepared by laser pyrolysis method. The hydrophilicity of AC-CNOs varied on the basis of particle size, which affected the amount of oxygen functional groups attached to the amorphous carbon. To confirm the water retention effect of the AC-CNOs, three different catalysts were incorporated into the MEA of the anode electrode, and a Pt@AC–CNO–3 with an average AC-CNO size of ∼164 nm exhibited a significantly improved performance under low RH condition. Moreover, to achieve a synergetic effect from both the anode and cathode, an additional AC-CNO layer was introduced on the cathode catalyst layer. The dual-side MEA with the hydrophilic catalyst layer at the anode and an additional carbon covering layer at the cathode showed significantly increased performance relative to the reference MEA, i.e., >80.2% under RH44%@90 °C conditions. [Display omitted] • AC-CNOs are prepared by irradiating a laser to hydrocarbons flame capable of mass continuous production. • The MEA with anode of Pt@AC–CNO–3, which is the most hydrophilic, shows the best performance under low humidity. • The carbon covering layer with AC-CNO-1 on the cathode plays an important role in water retention. • The synergistic effect of these layers significantly improves device performance under low humidity. [ABSTRACT FROM AUTHOR]

We demonstrated silicon nanoparticle synthesis using a novel CO2 laser pyrolysis reactor. The reactor was designed to have an elongated reaction zone more than 10 times longer than conventional laser pyrolysis systems by aligning the laser beam and precursor gas stream in the same direction within the simple tubular reactor. Experimental results showed that the elongated reaction zone contributed to production of silicon nanoparticles using SiH4 gas and influenced the size distribution of nanoparticles. Since the proposed reactor utilized the laser beam more efficiently without focusing the laser beam, it would be beneficial to large-scale production tolerating higher power CO2 lasers. Silicon nanoparticle synthesis mechanisms using a proposed reactor and synthesized nanoparticles were discussed in detail based on X-ray diffraction and transmission electron microscopy measurements. [ABSTRACT FROM AUTHOR]

TiO2 has been investigated as an alternative anode material candidate for lithium‐ion batteries for several years now due to its advantageous safety and rate capability in combination with its nontoxicity and abundance. Herein, the synthesis via laser pyrolysis is reported, which allows the single‐step, industrial‐scale realization of carbon‐coated TiO2 nanoparticles. The modification of the synthesis parameters enables the variation of the rutile‐to‐anatase phase ratio. Following comprehensive physicochemical and electrochemical characterization, both the higher and lower rutile‐to‐anatase ratios show very stable cycling in lithium battery half cells, whereas the extended presence of the rutile phase limits the achievable specific capacity and lowers the apparent lithium‐ion diffusion coefficient, which leads to relatively lower capacities at elevated current densities. [ABSTRACT FROM AUTHOR]

Zn/F co-doped SnO2 nanoparticles with a mean diameter of less than 15 nm and a narrow size distribution were synthesized by a one-step laser pyrolysis technique using a reactive mixture containing tetramethyltin (SnMe4) and diethylzinc (ZnEt2) vapors, diluted Ar, O2 and SF6. Their structural, morphological, optical and electrical properties are reported in this work. The X-ray diffraction (XRD) analysis shows that the nanoparticles possess a tetragonal SnO2 crystalline structure. The main diffraction patterns of stannous fluoride (SnF2) were also identified and a reduction in intensity with increasing Zn percentage was evidenced. For the elemental composition estimation, energy dispersion X-ray spectroscopy (EDX) and X-ray photoelectron spectroscopy (XPS) measurements were performed. In general, both analyses showed that the Zn percentage increases with increasing ZnEt2 flow, accompanied at the same time by a decrease in the amount of F in the nanopowders when the same SF6 flow was employed. The Raman spectra of the nanoparticles show the influence of both Zn and F content and crystallite size. The fluorine presence is due to the catalytic partial decomposition of the SF6 laser energy transfer agent. In direct correlation with the increase in the Zn doping level, the bandgap of co-doped nanoparticles shifts to lower energy (from 3.55 to 2.88 eV for the highest Zn dopant concentration).

The conditions of the laser-stimulated synthesis reaction of silicon-carbide nanoparticles are determined and their characterization is performed. The laser synthesis reaction of SiC particles in the gas phase is observed with the SiH4/C2H2 flow ratio in the range of 1.6–3.2. The temperature in the reaction-zone region is ~1400–1500°C. Silicon-carbide nanoparticles ~6 nm in diameter are fabricated and their composition is investigated. [ABSTRACT FROM AUTHOR]

Laser pyrolysis employs a laser to selectively heat and decompose nanoparticle precursors, inducing particle formation. While gaseous precursors are most common, liquid precursors would reduce cost and safety issues. Sufficiently volatile liquids can be delivered from a bubbler, but such precursors are unavailable for many metals. Spray-based delivery can accommodate both pure liquids and solutions of solid precursors. Here, we demonstrate low-cost ultrasonic spray delivery of precursor solutions for laser pyrolysis synthesis of zinc-containing nanomaterials. Using zinc acetate and thiourea produced nitrogen-doped ZnS nanoparticles in both wurtzite- and sphalerite-rich phases, while sub-10 nm zinc sulfide and zinc oxide nanoparticles were produced from zinc acetate and thioacetamide, or zinc acetate alone, respectively. Finally, we produced spherical and rod-like zinc fluoride nanoparticles under conditions where the photosensitizer, SF 6 , decomposes. These results demonstrate the potential of ultrasonic spray laser pyrolysis to produce materials of varied composition, crystal structure, and morphology. Unlabelled Image • A low-cost atomizer is designed to spray precursor solutions for laser pyrolysis. • ZnO and pristine ZnS nanoparticles below 10 nm diameter are synthesized. • Two different spherical and rod-like morphologies of ZnF 2 are produced. • N-doped ZnS nanospheres of tunable phase are synthesized in a one step process. [ABSTRACT FROM AUTHOR]

This study fabricated a portable, high-performance, and reagentless electrochemical devices using CO 2 laser-scribing process, which allowed localized carbonization of a non-conductive and low-cost polymer platform, i.e., phenolic-paper. The carbonized material was extensively characterized by Raman spectroscopy, XPS, XRD, SEM, and electrochemical impedance spectroscopy. The carbon-based electrodes were obtained from the photothermal process induced by CO 2 laser radiation and subsequently subjected to electrochemical treatment to fabricate a functional material with excellent conductivity and low charge-transfer resistance. Additionally, the laser-scribed electrodes presented a porous structure with graphene-like domains, thus indicating both potential for on-site electroanalytical applications and better performance than conventional carbon electrodes. Image 1 [ABSTRACT FROM AUTHOR]

We propose a concept of hybrid nanoelectronic-magnetic device made of magnetic Fe–C core–shell nanoparticles deposited onto prepatterned Si (111) substrate with basic circuitry made of metallic conductive lines. The synthesis of magnetic material and the creation of nanoelectronic prepatterned interdigitated die are reported and to prove the effectiveness in devices, their magnetotransport properties are investigated. Magnetic Fe/FeC nanoparticles, 11 nm diameter, with a core–shell structure have been prepared by laser pyrolysis. Two different layouts of prepatterned interdigitated die, have been conceived using e-beam lithography, with various geometries. A range of microscopy techniques, transmission electron, scanning and optical, were employed for morphological characterization of the as-obtained structures. Magnetic and magnetotransport characterization using SQUID magnetometry has been performed onto both the core–shell nanoparticles and onto the hybrid device obtained by depositing centrifugated and dispersed core–shell nanoparticles from liquid carrier solutions. From magnetotransport measurements, it has been revealed that the hybrid device made of Fe/FeC nanosized materials on prepatterned interdigitated die exhibit a large giant magnetoresistive (GMR) effect of about 8% at 300 K. This result is promising in view of the use of such devices as arrays of nanosensors and in spintronic applications. [ABSTRACT FROM AUTHOR]

Silicon‐germanium nanostructures are promising anode materials for high stability, high capacity, and fast cycling Li‐ion batteries. In this work, we report on the outstanding performance of new SiGe/Si core@shell nanoparticle heterostructures synthetized in one step by laser pyrolysis of silane and germane. By tuning the silane to germane ratio, the composition of Si100‐xGex alloy was readily adjusted. Nanoparticles with x=0, 20, 47, 77, and 100 were investigated and the composition of each alloy (including internal mixed phases) was confirmed by X‐ray diffraction and energy‐dispersive X‐ray spectroscopy. The electrochemical performances of the Si100‐xGex alloys were evaluated by cycling half cell batteries from C/5 to 5 C. The optimal trade‐off between stability and capacity was obtained in Si53Ge47 core shell nanoparticles alloy. This material exhibits the best performance reported so far for SiGe compounds, with a reversible specific capacity of 1695 mAh.g−1 after 60 cycles (90 % of its initial value). The (de)alloying properties of this optimal Si53Ge47 heterostructure were followed by operando synchrotron WAXS measurements, suggesting sequential lithiation of the various phases present in the material. The alloying process, combined with the realization of peculiar nanostructures composed of a Ge‐rich core and a Si‐rich shell, therefore allow to reach electrochemical properties suited for a practical application in energy storage device. [ABSTRACT FROM AUTHOR]

Typically, molybdenum dioxide (MoO2), as a promising anode material for LIBs, has triggered much attention owing to its high theoretical capacity, low electrical resistivity, high density, affordable cost and it has excellent physico-chemical properties. This report presents a bibliographic study on the synthesis of MoO2 and some results concerning a preliminary study of catalytic MoO2/Co materials synthesis by laser pyrolysis. The objective was to demonstrate the possibility to obtain molybdenum oxide nanoparticles from the laser pyrolysis method. In addition, the photocatalytic activity of the MoO2 nanospheres is investigated. [ABSTRACT FROM AUTHOR]

Pyrolytic carbon microelectrodes (PCMEs) are a promising alternative to their conventional metallic counterparts for various applications. Thus, methods for the simple and inexpensive patterning of PCMEs are highly sought after. Here, we demonstrate the fabrication of PCMEs through the selective pyrolysis of SU-8 photoresist by irradiation with a low-power, 806 nm, continuous wave, semiconductor-diode laser. The SU-8 was modified by adding Pro-Jet 800NP (FujiFilm) in order to ensure absorbance in the 800 nm range. The SU-8 precursor with absorber was successfully converted into pyrolytic carbon upon laser irradiation, which was not possible without an absorber. We demonstrated that the local laser pyrolysis (LLP) process in an inert nitrogen atmosphere with higher laser power and lower scan speed resulted in higher electrical conductance. The maximum conductivity achieved for a laser-pyrolyzed line was 14.2 ± 3.3 S/cm, with a line width and thickness of 28.3 ± 2.9 µm and 6.0 ± 1.0 µm, respectively, while the narrowest conductive line was just 13.5 ± 0.4 µm wide and 4.9 ± 0.5 µm thick. The LLP process seemed to be self-limiting, as multiple repetitive laser scans did not alter the properties of the carbonized lines. The direct laser writing of adjacent lines with an insulating gap down to ≤5 µm was achieved. Finally, multiple lines were seamlessly joined and intersected, enabling the writing of more complex designs with branching electrodes and the porosity of the carbon lines could be controlled by the scan speed.

The design or dimension of micro-supercapacitor electrodes is an important factor that determines their performance. In this study, a microsupercapacitor was precisely fabricated on a silicon substrate by irradiating an imprinted furan micropattern with a CO2 laser beam under ambient conditions. Since furan is a carbon-abundant polymer, electrically conductive and porous carbon structures were produced by laser-induced pyrolysis. While the pyrolysis of a furan film in a general electric furnace resulted in severe cracks and delamination, the laser pyrolysis method proposed herein yielded porous carbon films without cracks or delamination. Moreover, as the imprinting process already designated the furan area for laser pyrolysis, high-precision patterning was achieved in the subsequent laser pyrolysis step. This two-step process exploited the superior resolution of imprinting for the fabrication of a laser-pyrolyzed carbon micropattern. As a result, the technical limitations of conventional laser direct writing could be overcome. The laser-pyrolyzed carbon structure was employed for microsupercapacitor electrodes. The microsupercapacitor showed a specific capacitance of 0.92 mF/cm2 at 1 mA/cm2 with a PVA-H2SO4 gel electrolyte, and retained an up to 88% capacitance after 10,000 charging/discharging cycles.

C-encapsulated highly pure PtxCoy alloy nanoparticles have been synthesized by an innovative one-step in-situ laser pyrolysis. The obtained X-ray diffraction pattern and transmission electron microscopy images correspond to PtxCoy alloy nanoparticles with average diameters of 2.4 nm and well-established crystalline structure. The synthesized PtxCoy/C catalyst containing 1.5 wt% of PtxCoy nanoparticles can achieve complete CO conversion in the temperature range 125–175°C working at weight hourly space velocities (WHSV) of 30 L h−1g−1. This study shows the first example of bimetallic nanoalloys synthesized by laser pyrolysis and paves the way for a wide variety of potential applications and metal combinations.

Magnetic nanoparticles offer multiple utilization possibilities in biomedicine. In this context, the interaction with cellular structures and their biological effects need to be understood and controlled for clinical safety. New magnetic nanoparticles containing metallic/ carbidic iron and elemental silicon phases were synthesized by laser pyrolysis using Fe(CO)5 vapors and SiH4 gas as Fe and Si precursors, then passivated and coated with biocompatible agents, such as L-3,4-dihydroxyphenylalanine (L-DOPA) and sodium carboxymethyl cellulose (CMC-Na). The resulting magnetic nanoparticles were characterized by XRD, EDS, and TEM techniques. To evaluate their biocompatibility, doses ranging from 0-200 μg/mL hybrid Fe-Si nanoparticles were exposed to Caco2 cells for 24 and 72 h. Doses below 50 μg/mL of both L-DOPA and CMC-Na-coated Fe-Si nanoparticles induced no significant changes of cellular viability or membrane integrity. The cellular internalization of nanoparticles was dependent on their dispersion in culture medium and caused some changes of F-actin filaments organization after 72 h. However, reactive oxygen species were generated after exposure to 25 and 50 μg/mL of both Fe-Si nanoparticles types, inducing the increase of intracellular glutathione level and activation of transcription factor Nrf2. At nanoparticles doses below 50 μg/mL, Caco2 cells were able to counteract the oxidative stress by activating the cellular protection mechanisms. We concluded that in vitro biological responses to coated hybrid Fe-Si nanoparticles depended on particle synthesis conditions, surface coating, doses and incubation time. [ABSTRACT FROM AUTHOR]

A SiTiOC ceramic coating with outstanding tribological performance was prepared by laser scanning the organosilicon coating with different laser power. The composition and structure of the obtained SiTiOC ceramic coatings were analyzed by scanning electron microscopy (SEM), infrared spectroscopy (FTIR), Raman spectra, X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS) and transmission electron microscope (TEM). The tribological performance of the coatings was studied using a multi-functional reciprocating friction and wear tester. The results showed that the chemical structure (chemical bonding) of the coatings prepared at 0 W, 350 W, and 500 W laser powers included Si-O-Si, Si-C, and TiO 2 , while that prepared at 800 W was mainly composed of amorphous SiO 2 , indicating that the coating had higher ceramization. The SiTiOC ceramic coatings prepared by the present process effectively reduced the friction coefficient and wear volume of the steel substrate, which indicated that they had good anti-friction and wear resistance properties. [ABSTRACT FROM AUTHOR]