One-step Laser Ablation Research Articles

Rhodium nanospheres for ultraviolet and visible plasmonics.

The development and understanding of alternative plasmonic materials are crucial steps for leveraging new plasmonic technologies. Although gold and silver nanostructures have been intensively studied, the promising plasmonic, chemical and physical attributes of rhodium remain poorly investigated. Here, we report the synthesis and plasmonic response of spherical Rh nanoparticles (NPs) with sizes in the 20-40 nm range. Due to the high cohesive energy of this metal, synthesis and experimental investigations of Rh nanospheres in this size range have not been reported; yet, it becomes possible here using a green and one-step laser ablation in liquid method. The localized surface plasmon (LSP) of Rh NPs falls in the ultraviolet spectral range (195-255 nm), but the absorption tail in the visible region increases significantly upon clustering of the nanospheres. The surface binding ability of Rh NPs towards thiolated molecules is equivalent to that of Au and Ag NPs, while their chemical and physical stability at high temperatures and in the presence of strong acids such as aqua regia is superior to those of Au and Ag NPs. The plasmonic features are well described by classical electrodynamics, and the results are comparable to Au and Ag NPs in terms of extinction cross-section and local field enhancement, although blue shifted. This allowed, for instance, their use as an optical nanosensor for the detection of ions of toxic metals in aqueous solution and for the surface enhanced Raman scattering of various compounds under blue light excitation. This study explores the prospects of Rh NPs in the realms of UV and visible plasmonics, while also envisaging a multitude of opportunities for other underexplored applications related to plasmon-enhanced catalysis and chiroplasmonics.

Tunning Silver@Gold core@shell incorporated in poly (vinyl alcohol) via laser ablation: Antibacterial activity and cell viability behavior for wound healing

This study aims to bio-modulate Poly (vinyl alcohol) crosslinked by silver and gold nanoparticles fabricated by one-step laser ablation. The optical, cell viability, and antibacterial characterization of the fabricated films have been studied via different techniques. FTIR and XRD were used to investigate the molecular structures of the polymer matrix of Polyvinyl Alcohol incorporating gold and silver (Ag-Au NPs) created by laser ablation. XRD data illustrate the semicrystalline structure of PVA, with two hump peaks at 2θ = 8.52° and 2θ = 20.17° that are decreased when loaded with Ag-Au nanoparticles at different laser ablation times. The FT-IR spectra demonstrated a variation in the intensity of different peaks compared to the spectrum of the Polyvinyl Alcohol. This suggests that PVA and Ag-Au nanoparticles interacted and complexed in semicrystalline areas. The optical energy gap (Eg) reduces from 5.55 eV to 5.00 eV during direct transition and from 4.79 eV to 3.10 eV during indirect transition. The cell viability value for sample S2 was 91.7 ± 5.8%, indicating that both nanocomposites are biocompatible. S2 represents the high values of the inhibition zone, which make it preferred in antibacterial applications. The results demonstrate that Polyvinyl Alcohol/metal composite materials have excellent cell viability and antibacterial properties, implying that they may be suggested in antibacterial utilizations.

One-step laser ablation synthesis of magnetic nanoparticles with carbon coating for tribological applications

Among different materials able to reduce wear and friction in tribological couplings, there are lubricant nanofluids obtained by dispersing suitable nanoparticles into a host fluid. Carbon-based nanomaterials are known to be effective additives, but their efficiency can be further improved by combination with magnetic compounds. Unfortunately, the preparation of such bifunctional materials often require complex syntheses or need post-synthesis functionalization processes, thus increasing costs and reducing reliability. Herein, a simple and cost-effective one-step synthesis method, based on laser ablation in solution, is used to produce magnetic responsive nanoparticles surrounded by a carbon matrix to be exploited as lubricating additives. The lubricating colloidal solutions are thus easily obtained without the use of surfactants nor multi-step processes, which can contaminate the final product or increase production costs. They exhibit a very good stability and reduce the wear coefficient of almost 50% in presence of an applied magnetic field in respect to the base fluid alone. The importance of the presence of the carbon matrix surrounding the magnetic core to develop a positive tribological behaviour has been proved.

One-step laser ablation of Fe clusters supported on Ti3C2Tx nanosheets for enhanced NH3 sensing at room temperature

Supported metal clusters, different from single-atom and large metal-nanoparticle catalysts, possess distinct geometric and electronic structures and effective catalytic sites and thus exhibit unique catalytic activity. Here, an environment-friendly and effective method of using one-step pulsed laser ablation in liquid is reported for synthesizing the emerging gas-sensing materials of the Fe clusters supported on Ti3C2Tx MXene (L-Fe-Ti3C2Tx). Then, the sensors based on the L-Fe-Ti3C2Tx nanosheets are subsequently developed for the real-time detection of ammonia at room temperature. Moreover, it was found that the response of the L-Fe-Ti3C2Tx-232 sensor (in a synthesis condition) toward 10 ppm NH3 is improved to 64.03%, yet remains 39.19%, and exhibits significant repeatability even at high humidity, which makes it become a promising candidate in some special scenarios such as agriculture or human health applications. The excellent NH3-sensing properties can be attributed to the abundance of defective sites with stronger adsorption and the catalysis of the Fe clusters supported on the Ti3C2Tx nanosheets. This work may provide an effective methodology for the confinement of non-noble metal clusters on two-dimensional (2D) materials to further improve the performance of the gas sensors based on 2D materials.

Physical characterization and dielectric properties of chitosan incorporated by zinc oxide and graphene oxide nanoparticles prepared via laser ablation route

Zinc oxide and graphene oxide nanoparticles have been inserted into chitosan using a one-step laser ablation technique. Physical analysis of the prepared samples was carried out using various techniques. XRD patterns demonstrate the semicrystalline nature of Cs, with three hump peaks at 2θ = 11.52°, 2θ = 18.19°, and 2θ = 22.41° that were reduced when loaded with ZnO/GO nanoparticles at different laser ablation periods. The Fourier transform infrared (FTIR) spectra revealed a difference in the intensity of several bands when compared to the intensity of chitosan bands pure polymer. For this reason, it is possible that ZnO/GO nanoparticles interacted and bonded with Cs in semicrystalline regions. The optical energy gap was computed using UV–Vis measurements. The distribution of ZnO/GO NPs in the host polymer (chitosan) has manifested as white spots on the surfaces of the films, as shown by FE-SEM images. The A.C electrical conductivity, dielectric constant, and dielectric loss of Cs/ZnO/GO improved as the concentration of ZnO/GO NPs in the films increased. According to the studies, chitosan/zinc oxide nanoparticles have good optical properties, which could be employed in the development of novel energy devices.

Bioinspired microgroove arrays with drag reduction and hydrophobic properties

Reducing energy consumption is one of the most effective ways to solve the problem of energy shortage. In this work, nature-inspired paint microgroove arrays with different periods were fabricated using a one-step laser ablation method. A wind tunnel experiment was performed at two wind speeds, 27.7 and 33.3 m/s, to collect drag force data on smooth and structured paint coatings. The results showed that microgroove arrays oriented perpendicular to the flow direction were beneficial to drag reduction, and a drag reduction rate of up to 7.2% was obtained. Meanwhile, the microgroove arrays induced by laser ablation changed the wettability of the paint surface to hydrophobicity. The contact angle shows a slightly decreasing trend with an increase in the periodic scale. Furthermore, the anticorrosion properties of these microgrooves make them advantageous in harsh environments. The fabricated drag-reducing paint microstructures, with the features of self-cleaning and durability, have the potential to be applied on vehicles to realize speed improvement and energy saving.

Optical, thermal, and electrical conductivity strength of ternary CMC/PVA/Er2O3 NPs nanocomposite fabricated via pulsed laser ablation

By one-step Laser Ablation of a erbium plate dipped in Carboxymethyl cellulose/Polyvinyl alcohol (CMC/PVA ((50/50 wt %) solution, Er2O3NBs were fabricated. The Physical characterization of the produced nanocomposite films were performed via different technique. In addition. The electrical conductivity and dielectric properties for the prepared CMC/PVA/ErO3NPs have been investigated. FT-IR showed rapidly decreased in most peaks intensities after embedded of ErO3, which approve the complexationbetween CMC/PVA and Er2O3 NPs. The values of energygap were decreased by increasing the content of Er2O3NPs in CMC/PVA and increasing the laser ablation duration to 20 min, achieving 3.29 eV and 1.51 eV, respectively. AC results confirms the modification after the incorporation of Er2O3 NPs. The results show that using Er2O3 NPs make improvement in both electrical, thermal, and optical characteristics of the composite.

Impact of Laser Energy on Features of Carbon Nanostructure Materials Prepared by A One-Step Pulsed Laser Ablation in Water

Carbon nanoparticles (CNPs) formed by one-step laser ablation in deionized water were carefully studied. Scanning electron microscopy, atomic force microscopy, Raman spectroscopy, and UV–V spectroscopy were used to obtain morphological, chemical, and optical properties of CNPs. SEM outcomes established that the synthesized nanoparticles are semi-spherical with a wide particle size distribution. Raman investigation showed two typical and expected peaks ~ (1300 - 2700) cm−1, which are confirming to transverse and longitudinal modes of the carbon structure. The absorption spectra proved that the intensity of spectra increases as particle size and concentration increase.

Antibacterial Activity of TiO2 Nanoparticles Prepared by One-Step Laser Ablation in Liquid

Laser ablation in liquid was utilized to prepare a TiO2 NP suspension in in deionized distilled water using Q-switch Nd: YAG laser at various laser energies and ablation times. The samples were characterized using UV–visible absorption spectra obtained with a UV–visible spectrophotometer (UV-Vis,) Fourier transform infrared (FTIR), X-ray diffraction (XRD), and transmission electron microscope (TEM). While, UV-Vis spectra showed the characteristic band-to-band absorption peak of TiO2 NPs in the UV range. FTIR analysis showed the existence of O-Ti-O bond. XRD patterns indicated the presence of (101) and (112) plane crystalline phases of TiO2. TEM images showed a spherical-like structure of TiO2 NPs with various size distributions depending on the ablation period. It was also found that there is a relationship between laser ablation time and TiO2 NP size distribution, where longer ablation times led to the smaller size distribution. The antibacterial activity of TiO2 NPs was evaluated with different species of bacteria such as Escherichia coli, Pseudomonas aeruginosa, Proteus vulgaris, and Staphylococcus aureus, using the liquid approach. The optimum activity of TiO2 NPs is found to be against E. coli at 1000 μg mL−1. Furthermore, adding, TiO2 NPs (1000 μg mL−1) in the presence of amoxicillin has a synergic effect on E. coli and S. aureus growth, as measured by the well diffusion method. However, both E. coli (11.6 ± 0.57mm) and S. aureus (13.3 ± 0.57mm) were inhibited by this process.

Bioinspired Geometry-Gradient Metal Slippery Surface by One-Step Laser Ablation for Continuous Liquid Directional Self-Transport.

Liquid directional self-transport on the functional surface plays an important role in both industrial and academic fields. Inspired by the natural cactus spine and pitcher plant, we have successfully designed a kind of geometry-gradient slippery surface (GGSS) based on aluminum alloy materials which could actively achieve directional self-movement and also antigravity self-movement of various liquid droplets by topography gradient. The mechanism of liquid directional self-transport was theoretically explored through the mechanical analysis of the triple contact line, which was mainly related to the competition between the driven force induced by Laplace pressure and the adhesive force induced by viscous resistance. The adhesive force between the droplet and the surface was quantitatively measured using a homemade experimental apparatus and the results showed that the lateral adhesive force on the GGSS is much smaller than that on the original surface. Additionally, a series of quantitative experiments were conducted to explore the influence of droplet volume and vertex angle on the transport distance and velocity. Finally, we achieved the antigravity self-transport of the droplet on the inclined GGSS to further verify the self-transport ability of the GGSS. We believe that the proposed GGSS with liquid directional self-transport ability in the present work would provide some potential opportunities in modern tribo-systems to optimize the lubricating qualities, especially the lubrication and friction at the extreme contact interface.

Kinetically Stable Nonequilibrium Gold-Cobalt Alloy Nanoparticles with Magnetic and Plasmonic Properties Obtained by Laser Ablation in Liquid.

Nonequilibrium nanoalloys are metastable solids obtained at the nanoscale under nonequilibrium conditions that allow the study of kinetically frozen atoms and the discovery of new physical and chemical properties. However, the stabilization of metastable phases in the nanometric size regime is challenging and the synthetic route should be easy and sustainable, for the nonequilibrium nanoalloys to be practically available. Here we report on the one-step laser ablation synthesis in solution (LASiS) of nonequilibrium Au-Co alloy nanoparticles (NPs) and their characterization on ensembles and at the single nanoparticle level. The NPs are obtained as a polycrystalline solid solution stable in air and water, although surface cobalt atoms undergo oxidation to Co(II). Since gold is a renowned plasmonic material and metallic cobalt is ferromagnetic at room temperature, these properties are both found in the NPs. Besides, surface conjugation with thiolated molecules is possible and it was exploited to obtain colloidally stable solutions in water. Taking advantage of these features, an array of magnetic-plasmonic dots was obtained and used for surface-enhanced Raman scattering experiments. Overall, this study confirms that LASiS is an effective method for the formation of kinetically stable nonequilibrium nanoalloys and shows that Au-Co alloy NPs are appealing magnetically responsive plasmonic building blocks for several nanotechnological applications.

High-responsivity hybrid α-Ag2S/Si photodetector prepared by pulsed laser ablation in liquid.

We report the synthesis of α-Ag2S nanoparticles (NPs) by one-step laser ablation of a silver target in aqueous solution of thiourea (Tu, CH4N2S) mixed with cationic cetyltrimethylammonium bromide (CTAB) as surfactant. The effect of the CTAB surfactant on the structural, morphological, optical, and elemental composition of Ag2S NPs was evaluated using X-ray diffraction (XRD), transmission electron microscopy (TEM), scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDX), and UV–vis spectroscopy. The optical absorption decreased and the optical energy gap of α-Ag2S increased from 1.5 to 2 eV after the CTAB surfactant was added to the Tu solution. XRD studies revealed that the synthesized Ag2S NPs were polycrystalline with a monoclinic structure and that crystallinity of the nanoparticles was improved after adding CTAB. Raman studies revealed the presence of peaks related to Ag–S bonds (Ag modes) and the longitudinal optical phonon 2LO mode. Scanning electron microscopy investigations confirmed the production of monodisperse Ag2S NPs when using the CTAB surfactant. The optoelectronic properties of α-Ag2S/p-Si photodetector, such as current–voltage characteristics and responsivity in the dark and under illumination, were also improved after using the CTAB surfactant. The responsivity of the photodetector increases from 0.64 to 1.85 A/W at 510 nm after adding CTAB. The energy band diagram of the α-Ag2S/p-Si photodetector under illumination was constructed. The fabricated photodetectors exhibited reasonable stability after three weeks of storage under ambient conditions with a responsivity of 70% of the initial value.

A fluorescent and colorimetric probe of carbyne nanocrystals coated Au nanoparticles for selective and sensitive detection of ferrous ions

Dual-functional nanosensors for fluorescent and colorimetric detection of metal ions are generally shown in organic materials or complex organic-inorganic hybrid structures, and there are much few reports about dual-functional sensors made of pure and simple inorganic nanomaterials. Here, we report a fluorescent and colorimetric probe of the hybrid gold-carbyne nanocrystals structure for selective and sensitive detection of ferrous ions. We fabricate fluorescent carbyne nanocrystals (inorganic nanocrystals) capped with gold nanoparticles (CNCs@AuNPs) via a convenient one-step laser ablation in liquids. We demonstrate that, with involvement of ferrous ions, CNCs@AuNPs show fluorescence-quenching and color-producing properties, which make them be a double-channel platform for chemical and biomedical detection. With remarkably high selectivity towards ferrous ions over other metals, the fluorescent and colorimetric methods of the fabricated probe exhibit a detection limit of 14 μM and 1.2 μM, respectively. We also establish that the electron transferring plays an important role in facilitating these novel effects. These findings expand the applications of inorganic nanomaterials in chemical and biomedical sensing.

Laser drilling sub-10 nm holes on an island-shaped indium thin film

High-density nanohole arrays have a great value in many fields. However, fabrication of a sub-10 nm nanohole array in a simple and low-cost manner is extremely challenging using existing techniques. In this work, we present a one-step laser ablation method to prepare sub-10 nm nanohole arrays on the island-shaped indium thin film in the atmosphere condition with facile, low-cost and high-producing features. Induced by nanosecond laser irradiation, the center of an indium nano-island has a higher temperature than the edge region, and the nanohole forms on the top of each indium nano-island based on the shape-dependent thermal effect. The nanohole number on unit area can reach to 416/μm2 due to the dense distribution. This simple method can achieve a 3 nm nanohole that is the smallest nanohole obtained by laser fabrication technologies up to now as far as we know, reaching to λ/135 far beyond the optical diffraction limit. A primarily shape-dependent ablation mechanism is proposed and briefly explains the nanohole formation.

Nanosecond laser ablation assisted the enhancement of antibacterial activity of copper oxide nano particles embedded though Polyethylene Oxide/Polyvinyl pyrrolidone blend matrix

Via one-step Laser Ablation process, different contributions of copper oxide nanoparticles (CuONPs) were scattered through Polyethylene Oxide (PEO)/Polyvinyl pyrrolidone (PVP) blend matrix. The obtained films were characterized via XRD and FTIR. Their micro-structural features and morphological behaviors were investigated using TEM and FESEM. The CuONPs were formed in a spherical shapes with dimensions around 50 nm in case of processing time 5.0 min, while their size was deteriorated at t = 25.0 min to be around 30 nm upon TEM micrographs. In addition, surface roughness average was enhanced from 26.0 nm at no contribution of CuONPs reaching to 37.0 nm at the highest content. The composite films displayed antibacterial activity against E. coli and S. aureus upon CuONPs contribution. The antibacterial activity jumped from no effect at no contribution of CuONPs to be around 89 ± 4% and 82 ± 3% against E. coli and S. aureus respectively at their highest contribution. Therefore, it could be seen that these films were carried out using facile method and displayed a great effectiveness through biological environment which could encourage more investigations for these compositions to be suggested for wound healing applications.

Laser—synthesised Ag2S nanoparticles in liquid: effect of laser fluence on structural and optical properties

In this study, we report for the first time the preparation and characterization of silver sulfide nanoparticles (NPs) by one-step laser ablation of the silver target in thiourea aqueous solution without using a catalyst. The effect of laser fluence on the crystal structure, morphology, size and elemental composition of Ag2S NPs was investigated. X-ray diffraction (XRD) results show Ag2S NPs are polycrystalline with monoclinic phase and the variation in laser fluence affects the crystallinity of the synthesized NPs. The optical energy gap decreases from 2.2 eV to 1.6 eV as the laser fluence increases from 2.38 Jcm−2 to 6.77 Jcm−2. Transmission electron microscope (TEM) investigation confirms the formation of spherical Ag2S NPs and nanosheets morphologies and the particle size is found increases from 30 nm to 65 nm when the laser fluence increases from 2.38 Jcm−2 to 6.77 Jcm−2. The Raman spectra of Ag2S NPs show the presence of six active Raman peaks and their intensity increased with laser fluence.

Ambient Electrosynthesis of Ammonia Using Core-Shell Structured Au@C Catalyst Fabricated by One-Step Laser Ablation Technique.

This work reports the synthesis of core-shell structured Au@C composite through a simple one-step laser ablation technique. The results demonstrate that the Au@C with a mean nanosphere size of ∼8.0 nm is composed of a spherical shaped Au core and 1-2 layered graphitic carbon shell with abundant defects. As a nitrogen reduction reaction (NRR) electrocatalyst, the Au@C gives a large NH3 yield rate of 241.9 μg h-1 mgcat.-1 with a high faradaic efficiency of 40.5% at -0.45 V versus reversible hydrogen electrode in a 0.1 M Na2SO4 electrolyte (pH = 6.3) under ambient conditions, surpassing the performances of most aqueous-based NRR electrocatalysts recently reported. The 15N labeling experimental results demonstrate that the produced NH3 is undoubtedly originated from the NRR process catalyzed by Au@C. The superior NRR performance of Au@C can be ascribed to the ultrathin carbon layer, effectively inhibiting the aggregation of Au nanospheres during the NRR, and the abundant defects such as carbon vacancies existed in the ultrathin carbon layer, providing additional NRR catalytic active sites. Our theoretical calculation results further confirm the role of carbon vacancies in the electrocatalytic NRR.

SA101GENOME-WIDE ASSOCIATION OF WORD READING: OVERLAP WITH RISK GENES FOR NEURODEVELOPMENTAL DISORDERS

High-density nanohole arrays have a great value in many fields. However, fabrication of a sub-10 nm nanohole array in a simple and low-cost manner is extremely challenging using existing techniques. In this work, we present a one-step laser ablation method to prepare sub-10 nm nanohole arrays on the island-shaped indium thin film in the atmosphere condition with facile, low-cost and high-producing features. Induced by nanosecond laser irradiation, the center of an indium nano-island has a higher temperature than the edge region, and the nanohole forms on the top of each indium nano-island based on the shape-dependent thermal effect. The nanohole number on unit area can reach to 416/μm2 due to the dense distribution. This simple method can achieve a 3 nm nanohole that is the smallest nanohole obtained by laser fabrication technologies up to now as far as we know, reaching to λ/135 far beyond the optical diffraction limit. A primarily shape-dependent ablation mechanism is proposed and briefly explains the nanohole formation.

Large Area α-Cu2S Particle-Stacked Nanorod Arrays by Laser Ablation in Liquid and Their Strong Structurally Enhanced and Stable Visible Photoelectric Performances.

A flexible route is developed for fabrication of large area α-Cu2S nanorod arrays (NRAs) on the basis of one-step laser ablation of a copper foil in CS2 liquid. It has been demonstrated that the obtained products are the high-temperature phase α-Cu2S and consist of the nanorods vertically standing on the Cu foil, exhibiting the array. The nanorods were about 1 μm in length and around 100 nm in thickness and built by stacking the nearly spherical and ⟨110⟩-oriented nanoparticles (NPs) up. Such array can be peeled off from the foil and remain freestanding. Further, it has been found that the ablation duration, the laser power, and the foil surface state are crucial to the formation of the Cu2S NRA. The formation of such oriented NP-stacked Cu2S NRAs is attributed to the laser-induced generation of α-Cu2S NPs and the NPs' deposition/oriented connection growth on the surface-vulcanized copper foil. Importantly, the visible photocurrent response of the α-Cu2S NRAs is 8 times higher than that of the Cu2S NPs' film with the equivalent thickness and also larger than that of previously reported Cu2S, showing significantly enhanced photoelectric performances. As an application, such NRAs have exhibited markedly enhanced visible photocatalytic activity and highly stable recycling performances, compared with the α-Cu2S NPs. Further studies have revealed that the enhanced performances are attributed to the structurally enhanced light trapping effect of the NRAs as well as short and smooth carrier diffusion path in the oriented NP-stacked nanorods. This work provides a new and simple method for fabrication of the large area Cu2S NRAs with high and stable photoelectric performances.

Ultraviolet lasing in Zn-rich ZnO microspheres fabricated by laser ablation.

Zinc (Zn) surface plasmons (SPs) have been widely reported for their impressive performance in improving the optical properties of semiconductors. Zn is an effective metal with SPs response in the ultraviolet region, but the disadvantage of strong metal activity limits the application mentioned above. Here, in order to ensure the stability of metal Zn, ZnO/Zn microspheres were synthesized by an one-step laser ablation method to distribute Zn nanoparticles simultaneously on both inner and outer surfaces of ZnO microspheres. Lasing performance enhancement and a lower threshold were obtained in the composite which originates from the coupling between Zn SPs and the excitation light source. Accompanied by the lasing emission measurements, the coupling mechanism was explained through time-resolved photoluminescence spectroscopy (TRPL) for the samples by rapid annealing in situ. This work displays the results of lasing enhancement and the physical process of Zn SPs resonance in the ZnO/Zn microsphere.