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As nanomaterials find applications in an increasingly diverse range of fields such as wastewater treatment, biotechnology and flexible electronics, the demand for nanomaterials with specific proper...

Metal organic frameworks (MOFs) are fast emerging as a new class of crystalline hybrid porous materials originating from inorganic (metal) nodes connected by organic linkers. MOFs have gained tremendous interest in the materials science community owing to their versatile functionalities as a result of tailorable chemical activity, porosity, and morphology. In spite of the wide classes of MOF structures synthesized in recent years, rapid yet environmentally friendly fabrication strategies that allow precise morphological and structural control of these frameworks is still challenging. Herein, we report a facile route using high-energy laser ablation synthesis in solution (LASiS) to produce highly crystalline zeolitic imidazolate framework-67 (ZIF-67) structures by ablating Co targets in 2-methylimidazole (Hmim) solutions. Synthesis protocols presented here demonstrate for the first time the ability of LASiS to rationally tailor the sizes and shapes of MOF structures by adjusting solution-phase (reagent concentration and temperature) and laser parameters (ablation time). Our findings indicate that while the average MOF size is controlled by varying the organic linker to LASiS-generated metal ion stoichiometric ratio, tailoring of its morphology occurs via precise control of synthesis temperature and duration of ablation. Finally, a mechanistic picture for MOF formation via LASiS is presented.

The laser ablation synthesis in solution (LASiS) method has been widely utilized due to its significant prospects in laser microprocessing of nanomaterials. In this study, the LASiS method with the addition of different surfactant charges (cationic CTAB, nonionic TX-100, and anionic SDS) was used to produce Au NPs. An Nd:YAG laser system at 532 nm excitation with some synthetic parameters, including different laser fluences, ablation times, and surfactant concentrations was performed. The obtained Au NPs were characterized by UV-Vis spectroscopy, transmission electron microscopy, and zeta potential analyzer. The Au NPs exhibited the maximum absorption peak at around 520 nm for all samples. The color of Au NPs was changed from red to reddish by increasing the laser fluence. The surfactant charges also played different roles in the Au NPs’ growth during the synthesis process. The average sizes of Au NPs were found to be 8.5 nm, 5.5 nm, and 15.5 nm with the medium containing CTAB, TX-100, and SDS, respectively. Besides, the different surfactant charges induced different performances to protect Au NPs from agglomeration. Overall, the SDS and CTAB surfactants exhibited higher stability of the Au NPs compared to the Au NPs with TX-100 surfactant.

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.

Designing bioactive materials, with controlled metal ion release, exerting a significant biological action and associated to low toxicity for humans, is nowadays one of the most important challenges for our community. The most looked-for nanoantimicrobials are capable of releasing metal species with defined kinetic profiles, either by slowing down or inhibiting bacterial growth and pathogenic microorganism diffusion. In this study, laser ablation synthesis in solution (LASiS) has been used to produce bioactive Ag-based nanocolloids, in isopropyl alcohol, which can be used as water-insoluble nano-reservoirs in composite materials like poly(3-hydroxybutyrate-co-3-hydroxyvalerate). Infrared spectroscopy was used to evaluate the chemical state of pristine polymer and final composite material, thus providing useful information about synthesis processes, as well as storage and processing conditions. Transmission electron microscopy was exploited to study the morphology of nano-colloids, along with UV-Vis for bulk chemical characterization, highlighting the presence of spheroidal particles with average diameter around 12 nm. Electro-thermal atomic absorption spectroscopy was used to investigate metal ion release from Ag-modified products, showing a maximum release around 60 ppb, which ensures an efficient antimicrobial activity, being much lower than what recommended by health institutions. Analytical spectroscopy results were matched with bioactivity tests carried out on target microorganisms of food spoilage.

New developments in laser ablation have shown great potential as nanofabrication methodologies, offering many significant advantages over more traditional methods. Herein, we have developed a method for applying two of these techniques, confined atmospheric pulsed-laser (CAP) deposition and laser ablation synthesis in solution (LASiS), to the fabrication of a nanostructured sensor platform. Following deposition, additional steps were then used to crosslink the deposited nanostructures and fabricate counter and reference electrodes. Chronoamperometry and cyclic voltammetry (CV) were used to assess the effects of these crosslinking steps on the properties of the sensor surfaces. These experiments resulted in the development of a simple, inexpensive and readily scalable process for the fabrication of 3-electrode sensor systems. As an example of a readily measurable surface interaction, electrochemical impedance spectroscopy (EIS) was applied to demonstrate the use of these systems in the detection of 6-mercaptohexanol. This interaction was examined in real-time by measuring the change in the EIS of the sensor system over time following its exposure to the thiol. This experiment clearly showed a measurable EIS response, demonstrating the effectiveness of these newly fabricated sensors for the detection of a simple surface interaction and suggesting the future potential of these laser based methods as the basis for an inexpensive, facile, rapid and scalable sensor fabrication process.

Currently, most of the red colored glasses are still produced using cadmium sulfoselenide, despite its high toxicity. Alternative solutions, more environmentally friendly, have been sought, most of them going through the use of gold or copper nanoparticle, the color being obtained by striking. This work presents a new methodology for production of a red colored glass by the incorporation of gold nanoparticles in the melt, trying to take advantage of an amorphous silica layer involving the nanoparticles. Gold nanoparticles (AuNP) were produced by laser ablation synthesis in solution (LASiS), using a solution of tetraethyl orthosilicate (TEOS) and isopropanol (IPA). A xerogel was prepared using the TEOS:IPA:AuNp suspension, mixed with a alkaline-earth aluminosilicate colorless glass and melted at 1350 °C producing a glass with an intense and homogeneous ruby red color without the need of a striking stage.

As nanomaterials find applications in an increasingly diverse range of fields such as wastewater treatment, biotechnology and flexible electronics, the demand for nanomaterials with specific properties has increased. This increase is coupled with an increasing emphasis on nanomaterials with highly specific properties for specialised applications. Industrially, nanomaterials are produced via wet- chemical techniques which employ the use of solvents and reagents which are environmentally harmful. As we move forward with the use of nanomaterials, the ability to produce nanomaterials in a sustainable manner has become a topic of great significance. Towards this end, Laser Ablation Synthesis in Solution (LASiS) is a physical production technique capable of producing tailored nanomaterial colloids in a sustainable manner. These colloids are produced by ablating a solid target immersed in a solvent using a laser. Typically, LASiS is conducted in a batch process and in small volumes limiting commercial viability. To overcome this, there has been a move towards the use of continuous production via LASiS using flow systems. This allows an increase in nanomaterial yield, resulting in colloid concentrations approaching those of commer- cial colloids. This work investigates a new production technique incorporating a laminar recirculatory flow system to produce stable high concentration nano-silver colloids.

Driven by an ever-increasing demand for nanomaterials with specific functionalities, physical synthesis techniques such as Laser Ablation Synthesis in Solution (LASiS) have gained significant interest over in recent years. Commercial wet chemical synthesis methods, while having significantly higher nanomaterial yields than LASiS, typically have considerable negative environmental impact through the use of harmful reagents and solvents. LASiS therefore represents a route towards the sustainable “green” production of nanomaterials however the significant challenge to its commercialization is that of comparably low nanomaterial yields. Significant effort has been made towards increasing the production rates of LASiS, however many of the reported advances have relied on the use of high power (>20 W) or short pulse (

Porous graphene (PG) was obtained using one step laser process. Synthesis was carried out by laser ablation of nickel-graphite target under ultra-high flow of argon gas. The field emission scanning electron microscopy (FE-SEM) results showed the formation of a porous structure and the transmission electron microscopy (TEM) revealed that the porosity of PGs increase under intense laser irradiation. Structural characterization study using Raman spectroscopy, X-ray powder diffraction (XRD) and selected area electron diffraction (SAED) technique showed that the obtained PGs display high crystalline structure in the form of few layer rhombohedral graphitic arrangement that can be interpreted as the phase prior to the formation of other carbon nanostructures.

In the recent past, gold nanoparticles synthesized using pulsed laser ablation in biocompatible mediums has attracted scientific and technological interest. In this work, it is found that the gold nanoparticles prepared using laser ablation of gold target in water is inherently non-toxic. These particles have shown that they are photothermally active when excited with 532 nm laser line, in conjunction with the plasmon band. The surface charge of these nanoparticles is found to be negative. The X-ray photoelectron spectroscopy measurements indicated the possibility of partial oxidation of the surfaces of these gold nanoparticles and electron micrographs indicated that the surfaces of these particles are relatively smooth. Raman measurements made with crystal violet as probe molecules using these nanoparticles as substrates and Raman spectra from L929 cells after incubation with these gold nanoparticles have shown that they can enhance the scattered Raman signal.

In this paper, we demonstrate two-dimensional nanohole array substrates prepared using the visible laser ablation technique. We fabricated Au/polymer hybrid thin films where the Au nanoparticles were fixed onto the block copolymer substrate, which was used as the microphase-separated structure. The film was coated with a thin layer of poly(methyl acrylate), and was then irradiated with a nanosecond 532 nm pulsed laser light. The light excited the resonant plasmon absorption band of the Au nanoparticles. The nanoparticles underwent explosive vaporization via a superheated state, resulting in the formation of two-dimensional nanohole arrays on the film surface. The relevant mechanism aspects of the nanohole formation process and the relationship with laser fluence are presented.

In this paper, we investigate experimentally the effect of electric field on the size, optical properties and crystal structure of colloidal nanoparticles (NPs) of aluminum prepared by nanosecond Pulsed Laser Ablation (PLA) in deionized water. The experiments were conducted for two different conditions, with and without the electric field parallel to the laser beam path and the results were compared. To study the influence of electric field, two polished parallel aluminum metals plates perpendicular to laser beam path were used as the electrodes. The NPs were synthesized for target in negative, positive and neutral polarities. The colloidal nanoparticles were characterized using the scanning electron microscopy (SEM), UV–vis absorption spectroscopy and X-ray Diffraction (XRD). The results indicate that initial charge on the target has strong effect on the size properties and concentration of the synthesized nanoparticles. The XRD patterns show that the structure of produced NPs with and without presence of electric field is Boehmite (AlOOH).

Preparation of doped ZnO nanoparticles (NPs) represents a challenging task due to the tendency of self-compensation of the introduced defects by the intrinsic ones. One of the possible ways of achieving reliable p-doping in ZnO is dual acceptor doping, i.e. simultaneous introduction of two types of acceptors. In the present paper the capabilities of laser ablation and post-irradiation processes for preparation of N-doped and Ag-, N-co-doped ZnO NPs were investigated. In order to obtain doped ZnO NPs, Nd:YAG laser ablation of Zn in ammonium nitrate (NH4NO3) solution and sequential laser ablation of Ag and Zn in ammonium nitrate solution were used. The composition, structure and morphology of the prepared NPs were controlled through an additional treatment of the colloids by the second harmonic of the Nd:YAG laser. The influence of the ablation processes sequence and additional laser irradiation parameters on the morphology, structural, optical characteristics and chemical composition of the synthesized NPs was examined. The results obtained reveal that the doping takes place after laser ablation of zinc in ammonium nitrate and silver target in the ZnO colloid in NH4NO3 solution that was confirmed by X-ray photoelectron spectroscopy analysis indicating the substitution of N at O site.

The synthesis processes of metallic nanoparticles have seen a growing interest in recent years, mainly by the potential applications of the phenomenon of localized surface plasmon resonance associated with metallic nanoparticles. This paper shows a fast method to synthesize silver, gold and silver/gold alloy nanoparticles coated with a porous silica shell by the assisted laser ablation method in three steps. The method involves a redox chemical reaction where the reducing agent is supplied in nanometric form by laser ablation. In the first step, a silicon target immersed in water is ablated for several minutes. Later, AgNO3 and HAuCl4 aliquots are added to the solution. The redox reaction between the silver and gold ions and products resulting from ablation process can produce silver, gold or silver/gold alloy nanoparticles coated with a porous silica shell. The influence of the laser pulse energy, ablation time, Ag+ and Au3+ concentration, as well as the Ag+/Au3+ ratio, on optical and structural properties of the nanostructures was investigated. This work represents a step forward in the study of reaction mechanisms that take place during the synthesis of nanoscale materials by the assisted laser ablation technique.

Extended colloidal stability and high dispersion degree of nanolubricants are required to avoid nanoparticle deposition in combustion engines and to reduce friction and wear. In this study, the simple and rapid one-step technique of pulsed laser ablation in liquids is employed to synthesize precursor-free and highly-dispersed gold nanoparticles while the colloidal stability is measured by optical spectroscopy and transmission electron microscopy. We determine a remarkable colloidal stability at engine-like (2 h circulation, 150 °C, 6 bar) and ambient conditions for 9 months in terms of constant primary particle size. In contrast to additive-free oils, almost no agglomeration is observed, which might be attributed to the attachment of engine oil additives or pyrolyzed/oxidized molecules to the nanoparticles preventing attractive nanoparticle interactions.

Laser ablation of Zn target in water, ammonium nitrate and cetyltrimethyl ammonium bromide (CTAB) was carried out to synthesize spherical, nanoflakes, nanosquares, nanoflowers and branched nanorods ZnO structures. Morphology of the ZnO nanostructures is controlled by varying ambient condition around laser generated plasma by means of either liquid temperature or addition of surfactant CTAB. In situ heating at temperature to 45, 65 and 85 C resulted in morphology variation from spherical to nanoflakes while ex situ heating at 65 C resulted in aggregation of spherical nanoparticles into nanosquares. Finally, simultaneous variation of CTAB and temperature (in situ and ex situ) generated nanoflakes, nanoflowers, nanosquares and branched nanorods. Highly anisotropic nano-flakes, nano-flowers, nano-squares and branched-nanorods structures display distinct optical absorption and emission behavior.

Effects of laser fluence on the characteristics of copper sulfide (CuS) nanoparticles (NPs), produced by laser ablation method have been investigated experimentally. CuS nanoparticles were synthesized by the pulsed laser ablation of a high purity copper bulk in dimethyl sulfoxide (DMSO). Pulses of a Q-switched Nd:YAG laser of 1064 nm wavelength at 7 ns pulse width and different fluences were employed to irradiate the Cu solid target in DMSO. The Effects of laser fluence on the size, morphology, and structure of produced nanoparticles have been studied. Results show that the size distribution of the generated CuS nanoparticles was augmented by increasing the laser fluence. The rate of CuS nanoparticles production was increased by increasing the laser fluence. The bandgap energy for CuS nanoparticles was calculated to be 3.77–3.94 eV.

Silicon carbide (SiC) has been widely used in various technological applications, including power devices, light-receiving devices, and light-emitting devices. Several methods for fabricating SiC particles with nanometer dimensions have been reported, including carbo-thermal reduction of silica, chemical vapor deposition, laser pyrolysis, and microwave irradiation. To develop a new and simple method for fabricating SiC nanoparticles, we investigated the possibility of using femtosecond-laser ablation. In this paper, we report the formation of SiC nanoparticles by femtosecond-laser ablation on silicon immersed in hexane. By using a high-peak-power laser that can achieve extremely high temperatures and pressures on the silicon surface, SiC nanoparticles were successfully fabricated via ablation in hexane. In our experiments, femtosecond pulses from a Yb-fiber laser were used to irradiate to silicon single crystal. The laser was focused onto a spot on the silicon surface. After ablation, we evaluated the particles on the target substrate and particles in the irradiated hexane. Scanning electron microscopy revealed that the particles range in size from 100 to 400 nm. X-ray diffraction analysis indicated that the nanoparticles might be SiC. The characteristic X-ray photoelectron spectroscopy peaks of nanoparticles were Si-2p (100.1 eV) and C-1s (282.9 eV), which are identical to the characteristic peaks of SiC (John et al. in Handbook of X-ray photoelectron spectroscopy, Physical Electronics, Eden Prairie, 1995; Hijikata et al. in Appl Surf Sci 184:161–166, 2001; Shen et al. in Chem Phys Lett 375:177–184, 2003). We also used transmission electron microscopy and electron energy-loss spectroscopy to evaluate particles from the irradiated hexane. Such a simple method of fabricating SiC nanoparticles by femtosecond-laser ablation may open new possibilities in the development of growth techniques for SiC.

Nanomaterials of titanium oxide were prepared by pulsed laser ablation of a titanium metal target in distilled water. The ablation was performed at different laser energy (fluence) using a nanosecond pulsed Nd:YAG laser output of 1064 and 532 nm. A post-irradiation of titanium oxide nanocolloids obtained by ablation using 532 nm was carried out to explore its effects on the structure and properties. Analysis of morphology, crystalline phase, elemental composition, chemical state, optical and luminescent properties were performed using Transmission Electron Microscopy (TEM), X-Ray Diffraction (XRD), X-Ray Photoelectron Spectroscopy (XPS), UV–-vis absorption spectroscopy and room temperature photoluminescence spectroscopy. It was found that titanium oxide nanomaterial morphologies and optical properties were determined by ablation wavelength and fluence. Further, nanocolloids prepared by 532 nm ablation showed a crystalline phase change by laser post-irradiation. The results showed that pulsed laser ablation in liquid as well as post-irradiation were effective in modifying the final structure and properties of titanium oxide nanocolloids.

Products formed in laser ablation of single-crystal silicon beneath a water layer under irradiation with nanosecond pulses from a fiber-optic ytterbium laser have been studied. SEM images of structures deposited by dewatering of the colloid solution formed in the course of the ablation are presented. IR spectroscopy and Raman spectroscopy were used to determine their chemical composition and structural features.

Laser ablation of silver nanoparticles (NPs) was studied with laser post-ionization (LPI) time-of-flight mass spectrometry (TOF MS). Silver NPs containing ∼15 000 Ag atoms (4 nm radius) were deposited by soft landing (energy 3 eV/atom) onto indium tin oxide (ITO)/glass substrates. Laser ablation was performed using frequency-doubled Ti:sapphire nanosecond pulsed laser irradiation at three different wavelengths (371, 401, and 421 nm), whereas for post-ionization, pulses from an F2 laser were used. Laser fluences and time delay dependencies of Ag and In signals were obtained. Using these data, the temperature of the desorption source as well as its time duration were calculated. It was found that the peak temperature of NPs was above their melting point and they cooled down slowly, with temperature decay time of several hundreds of nanoseconds. This anomalous behavior was explained based on a model where the semiconducting ITO substrate is initially transparent to the desorption laser radiation but starts t...

The distinctive feature of upconverting compounds to absorb and emit light in the near-infrared region has made upconverting nanoparticles of great interest in various application fields. Nevertheless, these colloids show a highly hydrophobic behavior, and therefore, the use of a proper stabilizing agent is necessary in most cases. Although few chemical techniques for colloid stabilization are available, it is still difficult to achieve a fully reproducible synthesis method for stable upconverting nanoparticle colloids. In this work, upconversion 18 %Yb:1 %Er:NaYF4 nanoparticles were produced by ultrafast pulsed laser ablation in a water and 2-[2-(2-methoxyethoxy)- ethoxy]acetic acid (MEEAA) environment to assess the stabilization effect of the surfactant on the nanoparticle colloid properties. The effects of the laser fluence and MEEAA concentration on the nanoparticles′ properties were investigated by TEM, EDS, and emission spectra analyses. The results show that ultrashort pulsed laser ablation in liquid allows generating highly spherical nanoparticles with conserved stoichiometry and optical properties. Moreover, it is possible to obtain colloids with significantly higher stability and preserved optical properties by one-step PLAL processes directly in the MEEAA environment.

We report the electrochemistry of gold nanoparticles (AuNPs), prepared by Laser Ablation Synthesis in Solution (LASiS), via the electrocatalytic oxidation of glucose upon single nanoparticle collisions at inert microelectrodes. Spherical AuNPs with diameters in the range 20–30 nm, as determined by transmission electron microscopy, were synthesized by LASiS of a gold plate immersed in water. Nanoparticle collisions were electrochemically detected through the AuNP-catalysed oxidation of glucose at carbon fiber microelectrodes in alkaline solution, enabling the electrocatalytic detection of single AuNPs. This approach provides a basis for detecting and understanding the electrocatalytic properties of pristine nanoparticles in aqueous solutions. Keywords: Gold nanoparticles, Laser ablation, Glucose, Electrocatalysis, Nano-impact

Colloidal solution of iron oxide nanoparticles is synthesized by nanosecond pulsed laser ablation (Nd:YAG laser, 1064 nm, 7 ns, and 180 mJ) of a metallic iron target in water, and nanocrystalline powder is prepared from this solution by vacuum drying. A composition and structure of the material obtained are investigated by methods of electron microscopy, x-ray diffraction, and optical spectroscopy. It is established that oxide particles with average size of about 5 nm and Fe3O4 magnetite structure are mainly formed during ablation. Preliminary investigation of magnetic properties of the prepared nanoparticle powders shows that they can be in ferromagnetic and/or superparamagnetic states.

Bare nanoparticles synthesized by laser ablation in water have found their application in catalysis, spectroscopy and biomedical research fields. In this perspective, how to efficiently produce stable nanoparticles with controllable size is an important topic and has attracted a lot of interests. Here, we introduce a multiple-pulse laser as the ablation source. By changing the number of sub-pulses, the average size of nanoparticles can be tuned in a broad range from ∼120 nm to ∼4 nm. The demonstration in this article may offer a new approach to fabricate ultrafine nanostructures and also help the scientific study of the mechanism in laser ablation.

Laser ablation in liquids is actively used for generation of clean colloidal nanoparticles with unique shapes and functionalities. The fundamental mechanisms of the laser ablation in liquids and the key processes that control the nanoparticle structure, composition, and size distribution, however, are not yet fully understood. In this paper, we report the results of first atomistic simulations of laser ablation of metal targets in liquid environment. A model combining a coarse-grained representation of the liquid environment (parameterized for water), a fully atomistic description of laser interactions with metal targets, and acoustic impedance matching boundary conditions is developed and applied for simulation of laser ablation of a thin silver film deposited on a silica substrate. The simulations, performed at two laser fluences in the regime of phase explosion, predict a rapid deceleration of the ejected ablation plume and the formation of a dense superheated molten layer at the water-plume interface. The water in contact with the hot metal layer is brought to the supercritical state and transforms into an expanding low density metal-water mixing region that serves as a precursor for the formation of a cavitation bubble. Two distinct mechanisms of the nanoparticle formation are predicted in the simulations: (1) the nucleation and growth of small (mostly ⩽10nm) nanoparticles in the metal-water mixing region and (2) the formation of larger (tens of nm) nanoparticles through the breakup of the superheated molten metal layer triggered by the emergence of complex morphological features attributed to the Rayleigh-Taylor instability of the interface between at the superheated metal layer and the supercritical water. The first mechanism is facilitated by the rapid cooling of the growing nanoparticles in the supercritical water environment, resulting in solidification of the nanoparticles located in the upper part of the mixing region on the timescale of nanoseconds. The computational prediction of the two mechanisms of nanoparticle formation yielding nanoparticles with different characteristic sizes is consistent with experimental observations of two distinct nanoparticle populations appearing at different stages of the ablation process.

The issue of multidrug resistance (MDR) has become an increasing threat to public health. One alternative strategy against MDR bacteria would be to construct therapeutic vectors capable of physically damaging these microorganisms. Gold nanoparticles hold great promise for the development of such therapeutic agents, since the nanoparticles exhibit impressive properties, of which the most important is the ability to convert light into heat. This property has scientific significance since is exploited to develop nano-photothermal vectors to destroy bacteria at a molecular level. The present paper summarizes the latest advancements in the field of nanotargeted laser hyperthermia of MDR bacteria mediated by gold nanoparticles.

This review article highlights the recent advances of the synthesis and application of metal nanoparticles (NPs) fabricated via pulsed laser ablation in liquid (PLAL) phase and also introduces relevant NP formation mechanisms. Although wet-chemical approaches have been well established to synthesize colloidal metal NPs with various components and structures, some inherent drawbacks, such as reaction residuals and/or contaminations, largely limit some of their applications. The PLAL method has recently been developed as an alternative approach and received increasing attention for colloidal NP preparation, without involving complicated chemical reactions. In certain cases, by using PLAL, ligand-free and surface-clean NPs can be obtained and well dispersed in liquid, leading to the formation of a "surface-clean" NP dispersion. This unique feature renders PLAL-synthesised metal NPs attractive candidates for many interesting applications in catalysis, biology, sensing, and clean energy generation and storage. We conclude this review by proposing several interesting research directions and future challenges, from PLAL fabrication to applications. We hope this review can serve as a good reference and help with the further development of PLAL-NPs and their diverse applications.

Cubic phase zinc peroxide nanoparticles (ZnO 2 NPs) with an average diameter of ca. 9–15 nm have been synthesized via a fast nanosecond pulse laser ablation in liquid technique (PLAL), using H 2 O 2 aqueous solution as the ablation media and a 532 nm pulsed laser as the irradiation source and low-cost zinc powder as the solid target. Both the laser energy and ablation time potentially have a substantial influence on the formation of ZnO 2 NPs. Due to its relatively high oxidation level as well as its hydrophilic wetting behavior, the as-synthesized ZnO 2 NPs exhibit efficient photocatalytic degradation ability of Rhodamine B (RB) whilst remaining stable to photodegradation. The possible mechanisms of the photocatalytic behavior have been discussed in what follows.

Titanium dioxide (TiO2) is a wide bandgap semiconductor that is chemically stable, non-toxic, and economical compared to other semiconductors and has been implemented in a wide range of applications such as photocatalysis, photovoltaics, and memristors. In this work we studied the femtosecond laser ablation of titanium dioxide powders (P25) dispersed either in water or deposited onto a fluoride-doped tin oxide (FTO) substrate. The process was used as a route to induce the phase-transformation of TiO2 nanoparticles which was governed by laser parameters such as ablation time and power. It was observed that upon increase of the ablation time of TiO2 dispersion in water a bandgap widening occurred, leading to the possibility of bandgap engineering of TiO2 using controlled laser parameter profiles.

Performance enhancements in next-generation electrochemical energy storage/conversion devices require the design of new classes of nanomaterials that exhibit unique electrocatalytic and supercapacitive properties. To this end, we report the use of laser ablation synthesis in solution (LASiS) operated with cobalt as the target in graphene oxide (GO) solution in tandem with two different post-treatments to manufacture three kinds of hybrid nanocomposites (HNCs) namely, (1) Co3O4 nanoparticle (NP)/reduced graphene oxide (rGO), (2) Co3O4 nanorod (NR)/rGO, and (3) Co3O4 NP/nitrogen-doped graphene oxide (NGO). FTIR and Raman spectroscopic studies indicate that both chemical and charge-driven interactions are partially responsible for embedding the Co3O4 NPs/NRs into the various GO films. We tune the selective functionalities of the as-synthesized HNCs as oxygen reduction reaction (ORR) catalysts and/or supercapacitors by tailoring their structure–property relationships. Specifically, the nitrogen doping in the NP/NGO HNC samples promotes higher electron conductivity while hindering aggregation between 0D CoO NPs that are partially reshaped into Co3O4 nanocubes due to induced surface strain energies. Our results indicate that such interfacial energetics and arrangements lead to superior ORR electrocatalytic activities. On the other hand, the interconnecting 1D nanostructures in the NR/rGO HNCs benefit charge transport and electrolyte diffusion at the electrode–electrolyte interfaces, thereby promoting their supercapacitive properties. The NP/rGO HNCs exhibit intermediate functionalities towards both ORR catalysis and supercapacitance.

The search for new plasmonic nanostructures has received significant attention recently, owing to applications in diverse fields of nanoscience and nanotechnology, and being of interest for the life sciences. Metallic nanoparticles (NP) can strongly absorb and scatter light due to their ability to support localized surface plasmon resonances (LSPR) and, therefore, play an important role in plasmonic-based techniques such as surface enhanced Raman scattering (SERS) and metal-enhanced fluorescence (MEF). Interestingly, most research in the field is still confined to Ag, Au, and less intensively Cu nanostructures, and there is an open field for the investigation of other elements such as the poor metals. In this work, we investigate plasmonic properties of different metal nanoparticles, including the post-transition metals Bi, In, Pb, and Sn; the metalloid Sb; the transition metals Ni and Co; and the metal alloy Terfenol-D. All these nanoparticles were experimentally tested for LSPR and SERS, and our results indicate SERS responses and enhancement factors comparable to the ones obtained with gold NP. The nanoparticles used in this study were produced via laser ablation synthesis in solution (LASiS) and characterized by UV-Vis optical absorption, dynamic light scattering (DLS), transmission electron microscopy (TEM), atomic force microscopy (AFM) and surface area electron diffraction (SAED). These laser-synthesized NP present increased LSPR in the near UV spectral region, yet also reveal multi-peak LSPR extending towards the visible, an interesting feature to be considered in the development of plasmonic sensors. For the Raman experiments, several organic and biological molecules were tested, and SERS activity was demonstrated for diverse combinations of NP and test-analytes at varying concentrations, down to single molecule detection.

We demonstrate the catalytic performance of perovskite-based oxygen reduction reaction (ORR) catalyst based on LaMnO 3+δ nanoparticles (LMO NPs) prepared using the laser ablation synthesis in solution method. The ORR catalytic activity of the post-annealed LMO NPs was similar to that of commercial Pt/C catalysts due to the increased surface area as well as the perovskite crystalline structure of the LMO NPs. The mass and specific activities of the LMO NP catalyst annealed at 800 °C were 20 and 2.2 times higher than those of the bulk LMO, respectively. In a chronoamperometric stability test, our LMO NP catalyst (annealed at 800 °C) outperformed the Pt/C catalyst.