WO2016079681A1 - Procédé de production de colloïdes comprenant des nanoparticules - Google Patents

Procédé de production de colloïdes comprenant des nanoparticules Download PDF

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Publication number
WO2016079681A1
WO2016079681A1 PCT/IB2015/058901 IB2015058901W WO2016079681A1 WO 2016079681 A1 WO2016079681 A1 WO 2016079681A1 IB 2015058901 W IB2015058901 W IB 2015058901W WO 2016079681 A1 WO2016079681 A1 WO 2016079681A1
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nanoparticles
target
absorbance
metal
colloid
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PCT/IB2015/058901
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English (en)
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Chiara VERGARI
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Plasma Diagnostics And Technologies S.R.L.
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Publication of WO2016079681A1 publication Critical patent/WO2016079681A1/fr

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    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J13/00—Colloid chemistry, e.g. the production of colloidal materials or their solutions, not otherwise provided for; Making microcapsules or microballoons
    • B01J13/0004—Preparation of sols
    • B01J13/0043—Preparation of sols containing elemental metal
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J13/00—Colloid chemistry, e.g. the production of colloidal materials or their solutions, not otherwise provided for; Making microcapsules or microballoons
    • B01J13/0086—Preparation of sols by physical processes

Definitions

  • the present invention relates to the generation of metal nanoparticles, of pure metal or metal oxide, by means of ablation of a starting metal material with pulsed laser in the presence of a liquid, to obtain colloids.
  • ions of metal salts are used as reducing agents, such as sodium citrate or boron hydride salts in water.
  • the anions that derive from the metal salt dissolved in water, and those that derive from the reducing agents, are active as surfactants, reaching the goal that the resulting nanoparticles take a same electric charge that prevents them from aggregation.
  • a drawback of such methods is that there are many by-products generated by chemical reaction, that are deposited on the surface of the nanoparticles, affecting the activity of the nanoparticles changing the degree of purity of the colloids .
  • stabilizers for example polyethylene glycol (PEG) , which works as "spacer” between the nanoparticles .
  • PEG polyethylene glycol
  • a cellular toxicity of the colloids can derive owing to the presence of the stabilizers.
  • a pulsed laser with very high repetition frequency (lOkHz-100 MHz), which preferably has a duration of the repetition preferably between 0.1-10 ps and a pulse energy preferably between 1- 10 micro-Joule.
  • Other examples use a continuous flow of water for cooling the illumination region and a prism movable above the target.
  • the statistical distribution of the diameters of the nanoparticles (Fig. 4) is very dispersed and include spherical nanoparticles of big diameter (>20 nm) and smaller nanoparticles ( ⁇ 5nm) clearly elliptical.
  • the generated nanoparticles have a low stability, and consequently a stabilizer is added, for example a certain an amount of citrate. There is however a toxicity from the by-products of chemical reductions generated by the use of stabilizers.
  • a Nd:YAG laser source is used, with 25 picosecond pulse duration, 40 mJ pulse energy, at the essential wavelength of 1064 nm, and a 1kHz repetition frequency in said range of energy, focusing the laser beam with a 20cm lens.
  • a Nd:YAG laser source is used, with 25 picosecond pulse duration, 40 mJ pulse energy, at the essential wavelength of 1064 nm, and a 1kHz repetition frequency in said range of energy, focusing the laser beam with a 20cm lens.
  • Nd:YAG laser source prearranging a Nd:YAG laser source, with pulse duration comprised between 15 and 40 picoseconds, pulse energy comprised between 2 and 100 mJ, at the essential wavelength of 1064 nm or at the second harmonic of 532 nm or at the third harmonic of 355 nm, and repetition frequency up to a maximum of 1 kHz at said pulse energy;
  • the optical unit irradiates the target with focus of the laser beam located beyond the target, so that the target is irradiated in an illumination region of a predetermined diameter not less than 0.5 mm, this forming, starting from this region, a colloid with desired dimension, statistical distribution and concentration.
  • the illumination region of predetermined diameter is comprised between 0.5 mm and 5 mm, preferably between 0.5 mm and 2 mm.
  • the adjustment of the diameter of said illumination region is provided through said optical unit, such that nanoparticles are obtained of different size responsive to the diameter of the illumination region.
  • Said liquid solvent can be selected from the group consisting of: water, acetone, 2-propanol, PAMAM (polyamidoamine) , PEG (polyethylene glycol), oil for microscopy, whereas the target can be made of a metal or metal oxide, selected from the group consisting of: Au, Ag, Ti, T1O2, Cu, Fe and Pd, pure or in the form of alloys of the above described metals, as well as other metals, metal alloys and metal oxides.
  • a metal or metal oxide selected from the group consisting of: Au, Ag, Ti, T1O2, Cu, Fe and Pd, pure or in the form of alloys of the above described metals, as well as other metals, metal alloys and metal oxides.
  • the liquid solvent is double distilled water.
  • the double distilled water is preliminarily treated keeping it at a predetermined conditioning temperature and then sterilized.
  • the conditioning temperature is about 100°C and the sterilization temperature is about 120°C. This way, a high reproducibility of the process for ablation is obtained and a much higher stability with time of the colloids obtained.
  • the liquid solvent in the workspace has a fixed flow rate less than 10 ml/min.
  • the lens fluid flow is sufficient for not requiring cooling of the liquid and for limiting at most the turbulence of the liquid solvent, reducing at most the collisions between metal nanoparticles capable of forming aggregations which would change the final quality of the colloid.
  • Such a lens speed allows a non-turbulent conveyance of the liquid solvent and such slowness requires several minutes for a complete replacement of the liquid surrounding the target, avoiding to affect the process of stabilization of the nanoparticles and allowing to obtain spherical nanoparticles .
  • a cuvette is arranged in which the target is put.
  • the cuvette can be for example a transparent container with an inlet and an outlet to allow the solvent to enter and the colloid to exit .
  • the workspace is arranged in such a way that the target rests on a plane support and is covered by a column of liquid of height comprised between 1-2 cm .
  • the target has a translation movement having a speed with respect to the laser beam less than 0.1 cm/sec.
  • Such low speed allows, on the one hand, not to move the optical unit, and on the other hand allows a gradual detachment of the nanoparticles by the target, avoiding turbulences of the liquid and allowing an homogeneous dispersion of the nanoparticles in the liquid solvent, avoiding aggregations between the particles.
  • the target is mounted in a cuvette with a motor that makes it possible a stepped motion in the directions x, y, to obtain a desired ablation and avoiding a re-deposit of the nanoparticles or the production of oxide on the surface of the target.
  • the optical unit comprises at least one lens and a prism with anti reflective coating. This way, losses for reflection are eliminated during the movement beam entrance and exit surfaces of the prism.
  • the optical unit comprises a lens and a deflection mirror. This way, the deflection mirror avoids reflection losses the cost of a prism with anti- reflective coating.
  • the optical unit has a converging lens with focal length of 20-30 cm.
  • the optical unit is arranged for deflecting the laser beam for hitting perpendicularly the target. This way, a non-homogeneity of the distribution of energy due to refraction of the liquid of the laser beam in the illumination region is avoided.
  • the laser beam is converted from the essential harmonic at the second harmonic, which has an energy efficiency about 50% less, the second harmonic being used both for remodulating the shape of the nanoparticles and for limiting the size less than 4 nm and very narrow statistical distribution.
  • the second harmonic is used for Au in acetone or for Pd in 2-propanol.
  • the third harmonic can be used for similar purposes.
  • a spectroscopic system is arranged that provides an absorbance spectrum in situ of the colloid in the workspace downstream of the illumination region, the laser beam and the optical unit being adjusted responsive to the absorbance spectrum so that the absorbance spectrum in situ corresponds to a predetermined range of metal nanoparticles, in particular with an average diameter comprised between 1 and 10 nm, spherical shape, crystalline structure and substantial absence of aggregations.
  • the absorbance spectrum in situ corresponds to a range of nanoparticles with an average diameter comprised between 1 and 5 nm for biomedical applications.
  • the spectroscopic system operates with UV-Vis spectroscopy, and the absorbance spectrum is sampled for each pulse, in the range UV-Vis from 200 to 1100 nanometres.
  • UV-Vis the absorbance spectrum
  • the shape, size and statistical distribution can be determined for each pulse, and this is very useful when the pulse energy is larger than a certain ablation threshold, which depends upon the material and the size of the illumination region of the target invested by the laser.
  • the measurement in situ of the UV- Vis absorbance of the colloid for controlling the stability provides an analysis of the spectral position of the plasmonic resonance and an analysis of the width of the plasmonic resonance.
  • the absorbance is determined by means of optical fibres, ending with a collimator, which collimates a light beam coming from a UV-Vis lamp and crossing the colloid in the volume, until the light beam has been collected by another collimator connected, through optical fibres, to a low resolution wideband spectrometer which operates between 200 and 1100 nm.
  • the spectral distribution of the absorbance is computed by a program for controlling the concentration of the colloid measured by a "Mie fit" equation starting from the absorbance.
  • the admissible threshold of absorbance is less or equal to 10, in order to ensure optimal stability to the colloid.
  • the measurement in situ of the absorbance is carried out for values of absorbance between 1 and 2, whereas for values of absorbance between 3 and 10 a step is provided of collecting the colloid, and diluting it in an auxiliary container, which is crossed by the collimated light beam coming from the UV-Vis lamp for determining the absorbance .
  • the target is displaced of one step after a predetermined number of laser pulses according to a predetermined function according to values of recorded absorbance.
  • the function is configured for adjusting the movement of the cuvette in at least one of the directions x, y responsive to the absorbance, so that, if an incipient decrease of the absorbance is observed, or a stop in the growth of the absorbance, the target is displaced for presenting not ablated portions of the target, until the absorbance starts growing again.
  • the function provides a linear growth of the absorbance.
  • the colloid has shape, average diameter, statistical distribution and optimal concentration of the nanoparticles , and it is possible to obtain a production of nanoparticles in the colloid substantially proportional to the number of pulses and/or to the power, with total reproducibility of the desired quality substantially independent from the production rate, in the range of power between 2-100 mJ and frequency less than 1 kHz.
  • the production of the colloid is carried out in the ablated cloud of nanoparticles, so-called "plume”, in a time of about one hundred microseconds, the repetition frequency of the pulses must not exceed 1 kHz for not to affect the features of the colloid produced in a single pulse.
  • the frequency range of pulses is increased between 50-100 Hz under a same energy for pulse.
  • the frequency of the production rate i.e. the amount of nanoparticles delivered per time unit, is greater with respect to what can be obtained by increasing the number of pulses under a same nominal power.
  • the liquid solvent is acetone and the laser emits the second harmonic at 532 nm with pulse energy about 15 mJ and diameter of the illuminated region 0.5-5 mm, in particular 0.5-2 mm, such that nanoparticles are obtained with an average diameter of 2.5 nm with dispersivity within 10% of the average diameter.
  • the nanoparticles are obtained from a target of silver, where to the liquid solvent a solute is added selected from the group consisting of: Sodium chloride, Lithium chloride.
  • the solute is added to the liquid solvent up to a 10 ⁇ 3 molar concentration.
  • the nanoparticles are obtained from a titanium target and the laser has a pulse energy selected from the group consisting of:
  • T1O2 which with pulse energy between 2 and 10 mJ or between 50 and 100 mJ is in the Rutile form and with pulse energy between 10 and 50mJ is in the Anatase form.
  • the nanoparticles are obtained from an iron target.
  • colloidal suspensions are obtained of nanoparticles of Fe that include iron oxides in the form of magnetite with strong magnetic characteristics and a reversible behaviour in an external magnetic field.
  • the nanoparticles are obtained from a target of Palladium with 2-propanol as liquid solvent, and the laser emits the second harmonic at 532 nm with pulse energy between 5-40 mJ and diameter of the illuminated region 0.5-5 mm, such that nanoparticles are obtained with an average diameter of 2 nm and dispersivity within 10% of the average diameter.
  • the pulse energy is between 50- 100 mJ, such that nanoparticles of Pd metal are obtained dominating with respect to palladium nanoparticles oxide, PdO. This way, palladium nanoparticles are obtained that can be used in catalysis and hydrogen storage applications .
  • an apparatus that carries out said method, in any of its embodiments.
  • Fig. 1 diagrammatically shows a possible implementation of the method for making nanoparticles by laser ablation in a liquid according to the invention
  • Fig. 1A diagrammatically shows a possible implementation of the method for making nanoparticles by laser ablation of a target in a cuvette with liquid solvent in motion;
  • Fig. 2 shows the cuvette of Fig. 1A where the nanoparticles are generated associated with a system for controlling, for each pulse, the growth of the concentration of the colloid and its characteristics;
  • Fig. 3 diagrammatically shows a step of maintenance of the flow of the fluid through the above described cuvette of Fig. 1A and an auxiliary system for measuring the absorbance, after dilution, when the absorbance in the cuvette is larger than 1-2;
  • Fig. 4 shows the growth of the absorbance of a colloid of Au nanoparticles in double distilled water, responsive to the number of laser pulses produced by the waves of said laser at 1064 nm, and the growth of the plasmonic resonance, and below it shows the linear growth of the plasmonic peak and, accordingly, of the concentration, with diameter of the illuminated region 1.4 mm and pulse energy 15 mJ;
  • Fig. 5 above shows the growth of the absorbance during the production of nanoparticles of Ag when the flow circulation system is operating, and below it shows the cyclical change of the liquid in the cuvette ;
  • HRTEM high resolution
  • Fig. 10A is the crystalline structure
  • Fig. 11 shows the stability of a colloid of nanoparticles of Ag generated with said method in double distilled water with waves at 1064 nm of said laser, with diameter of the illuminated region 1.4 mm and pulse energy 8 mJ, where a first line is the absorbance spectrum of the sample during the production and the other line is the absorbance spectrum of the same sample after 2 years;
  • FIG. 12A-12E show a succession of interactions of nanoparticles of magnetite with an external magnetic field, where: 12A - just produced sample, 12B - after applying a magnetic field, 12C - after one night, 12D
  • Fig. 13 shows a comparison of the absorbance spectrum of a sample of magnetite just produced and of the same sample after the succession of steps of Fig. 12.
  • a method and a relative apparatus for making colloids consisting of metal nanoparticles, of metal or metal oxide provide the production, by a source 15, of a Nd:YAG laser beam 1, with pulse duration comprised between 15 and 40 picoseconds, pulse energy comprised between 2 and 100 mJ, at the essential wavelength of 1064 nm and repetition frequency up to a maximum of 1 kHz in the range of energy for pulse.
  • the source 15 can provide switching the generation of the laser beam 1 even at the second harmonic at 532 nm or at the third harmonic at 355 nm.
  • a metal target 7 made of metal or metal oxide, for example Au, Ag, Ti, Cu, Fe or Pd, pure or in the form of alloys of the above described metals, is immersed in a liquid solvent 5, for example acetone, 2- propanol, PAMAM, PEG, oil for microscopy, water, preferably double distilled water.
  • a liquid solvent 5 for example acetone, 2- propanol, PAMAM, PEG, oil for microscopy, water, preferably double distilled water.
  • An optical unit 11 is configured for deflecting and concentrating on target 7 the laser beam 1 emitted by the laser source 10.
  • Target 7 is irradiated with the laser beam 1, thus producing a colloid 14 of the metal nanoparticles in the liquid solvent 5.
  • optical unit 11 focalizes the laser beam 1 that irradiates target 7 with focus 12 of the laser beam 1 located beyond target 7, so that target 7 is irradiated in an illumination region 13 of predetermined diameter not less than 0.5 mm, thus producing the colloid 14 about the illumination region 13, with desired dimension, statistical distribution and concentration of the nanoparticles for the respective uses.
  • the morphology of the nanoparticles is easily controllable, for example spherical shape, which for many applications is preferred.
  • the energy of the laser beam is distributed in illumination region 13 in a homogeneous way, with a mechanism of production and stabilization of nanoparticles that is "gentler" than other known methods.
  • the production of nanoparticles is carried out without that phenomena capable of generating undesirable shock waves, cavitation bubbles or intense transmission of plasma are present, due to the concentration in a single point of the laser energy, which can generate an abundant ablation, but a disordered production of nanoparticles, which brings quickly to aggregations, which prevent a control of the dimension, statistical size distribution and concentration of the colloid.
  • the control of the morphology of the particles is jeopardized. Therefore, the known methods require specific additives to limit the aggregation and increase the stability.
  • the colloid is formed starting from the illumination region 13 and slow colloidal streams 14 parallel are generated that rise towards the above with very slow convective and non-turbulent movement against the flow direction of the laser beam 1 that hits the target.
  • the slowness of the convective movement allows keeping steady the characteristics of the colloid and attract fresh pure liquid solvent 5 that is present in workspace 6.
  • the ablation is carried out for mutual interaction of many phenomena, i.e. evaporation, thermionic transmission and ionization heat assisted by photons.
  • the ablated material is mainly consisting of ions and atoms that are surrounded by the liquid in a thin thickness of evaporated liquid solvent. Such zone surrounding the laser beam above the target in which move the detached nanoparticles is called "plume”.
  • the production of nanoparticles is carried out in the plume during the expansion and, actually, ends when the pressure of the plume is equal to the pressure of the environment.
  • the ablated material is mainly made up of ions and atoms.
  • the atoms are produced by phases of the expansion.
  • a certain amount of clusters is also produced during the evaporation .
  • the ratio between said species depends upon the energy of the pulse and upon the illumination region, i.e. by the fluence of the laser energy that hits the target at each pulse, since the duration of each laser pulse is always comprised between 15-40 picoseconds.
  • the density of the species is large enough to permit an aggregation forming the nanoparticles.
  • the ions and the atoms are attracted by each other by Van-der- Waals forces, like dipole-dipole links, including permanent dipoles and rotors, and ione-dipole links (permanent or rotors) .
  • the stabilization of the nanoparticles is attained during the expansion of the plume after each laser pulse so that the final characteristics of the colloid, i.e. the size and their statistical distribution and concentration, is obtained from the sum of nanoparticles formed in a single pulse multiplied by the number of pulses. After several hundreds of microseconds, no further significant formation of nanoparticles is observed. This is another evidence that the nanoparticles are stabilized during the expansion of the plume.
  • the diameter of the illuminated region 13 is preferably adjustable by optical unit 11, and an increase of the nanoparticle size can be obtained responsive to an increase of the diameter of the illumination region 13.
  • a possible exemplary embodiment of an apparatus for making nanoparticles with laser ablation provides a picosecond pulsed laser beam 1 focused by optical unit 11 that can comprise a lens 3 with a prism 4, directed towards target 7.
  • optical unit 11 can comprise a lens 3 with a prism 4, directed towards target 7.
  • the prism preferably an anti-reflective prism, a mirror or a path of mirrors can be used.
  • the diameter of the illumination region is preferably comprised between 0.5 mm and 5 mm, preferably between 0.5 mm and 2 mm.
  • the focus of the laser beam is located under target 7, which is immersed in liquid volume 5, for example defined in a cuvette 6.
  • the height of the liquid of volume 5 above target 7 is preferably set between 1 and 2 cm.
  • the adjustment of the illuminated region on target 7 can be set by a micrometric screw 2.
  • the volume of liquid can be in motion, for example between an inlet 8 and an outlet 9.
  • the flow between the ducts 8 and 9 is selected in such a way that in the workspace is has a fixed flow rate less than 10 ml/min, allowing a full liquid substitution in the cuvette within several minutes, and then the substantial absence of turbulence .
  • Cuvette 6 can be located on a platform 10 connected to a step motor (not shown) , controlled by computer, which can move platform 10 and, accordingly, the target directions x, y.
  • the step motor has been chosen in order to cause platform 10 to move not continuously but in a stepped way. Each step can be triggered after a certain number of laser pulses 1, which depends upon the repetition frequency of the laser source 15 and upon the material of target 7.
  • the motor of platform 10 can cause a transmission screw (not shown) to transmit a stepped motion in the direction x or y of about 1-2 mm, so that the target is struck by the laser beam 1 in a not ablated region, and to stop again.
  • Fig. 2 shows a detail of the above described cuvette 6 of Fig. 1 with an apparatus 20 for measuring the absorbance for each pulse.
  • the light 24 emitted by the UV- Vis lamp 23 is conveyed via a fibre and a collimator (not shown) through the liquid 5 and is collected by another collimator (not shown) connected to the fibre 25 with a spectrometer 26 broadband that covers a spectral range of 200-1100 nm.
  • the collected spectrum is treated by a personal computer 27 that operates also the laser 15 similar to that of Fig. 1.
  • the UV-Vis absorbance computed with a so-called Mie fit algorithm, a control of quality of the generated nanoparticles is attained.
  • the absorbance can be determined in an auxiliary system in fluid communication with the cuvette (see Fig. 3) .
  • a value of 10 of the absorbance corresponds to the maximum concentration which ensures stability of the colloid.
  • the growth of the absorbance makes it possible to control the amount of ablated material.
  • the oxidation of the surface of target 7, during the production of nanoparticles of Ag can slow down the ablation of material so, causing a grow of absorbance in a way less than linear.
  • the motor moves the target exposing in a zone not yet ablated and it stops.
  • FIG. 3 shown a possible exemplary embodiment of a system with liquid circulation is diagrammatically shown.
  • a container 31 contains at first the liquid solvent 5.
  • a peristaltic pump 32 fills cuvette 6 until the height of the column of liquid 5 reaches typically 1-2 cm.
  • An inlet valve 33 is open whereas an exit valve 35 is closed.
  • the laser 1 starts the ablation to form the colloid 14 (Fig. 1 or 1A) and said system measures in situ the growth of the absorbance.
  • the valve 5 opens and the peristaltic pump 36 generates a non- turbulent a flow, so that in the cuvette a flow rate less than 10 ml/min is attained.
  • auxiliary peristaltic pump 27 injects a fraction of liquid in an auxiliary cuvette 28 where the absorbance is determined with the same apparatus of Fig. 2, or with a similar apparatus, after controlled dilution .
  • Fig. 4 shows an example of the absorbance responsive to the number of pulses during the ablation of Au (upper box) .
  • the lower box shows the growth of the peak value of plasmonic resonance that has a clearly linear behaviour.
  • Fig. 5 shows the operation of the system of Fig. 3 during the production of nanoparticles of Ag.
  • the sawtooth shape of the diagram in the lower box defines the operation of the flow conveyance system as described in Fig. 3.
  • Figs. 6-6A-6B, 7-7A-7B, 8-8A-8B show the characterisation of Au nanoparticles generated in double distilled water with waves at 1064 nm of a Nd:YAG laser with 25 ps duration and repetition frequency 10 Hz, diameter of the illuminated region 1.4 mm.
  • the average diameter decreases when the pulse energy increases as expected on the basis of the previous description of the production method.
  • the delivered energy grows, the fraction of ions in the ablated material grows as well.
  • the number of nanoparticle seeds increases but, at the same time, the amount of neutral atoms available that is responsible to the growth of a nanoparticle about the seed decreases.
  • the statistical distribution of the diameters narrows down.
  • the diameter of the illuminated region between 0.5 mm and 5 mm, preferably between 0.5 mm and 2 mm, permits to limit the fluctuations of the amount of ablated material, which would be caused by the roughness of the target. More precisely, the diameter of the illuminated region has to be sufficiently large to mediate such roughness in such a way that the amount of ablated material is about the same in different zones of the target. Furthermore, the illuminated region is selected sufficiently large to manufacture a sufficient amount of material for each pulse.
  • the nanoparticles of gold (Au) generated in double distilled water, at 1064 nm wavelength, are essentially spherical and their average diameter decreases by increasing the energy for each pulse. Typical average diameters are 3-8 nm. Larger diameters are obtained by changing the illuminated region on the target and/or the energy for each pulse.
  • the Au nanoparticles in acetone, generated with the second harmonic of said laser to 532 nm, have spherical shape with an average diameter of 2.5 nm and are monodispersed (Fig. 10-lOA-lOB) .
  • Said nanoparticles can be transferred in double distilled water maintaining the same characteristics and without aggregation.
  • the nanoparticles of silver (Ag) are generated in double distilled water, with the 1064 nm wavelength, mainly with spherical shape with an average diameter 1-5 nm with pulse energy between 8-30 mJ. Owing to the strong tendency to the oxidation, larger than Au, the plasmonic resonance is shifted towards the red of about 10-20 nm with respect to the calculated value of 385 nm expected for metal Ag.
  • the surface of the silver nanoparticles can be functionalized, without loss of stability, by adding Lithium chloride or Sodium chloride for increasing bactericide and anti-mould characteristics of the colloid. Up to a 10-3 Molar concentration of the salt, the main mechanism relates to the change of hydroxylic ions with chloride ions. This increases the negative charge, and then the stability, of said nanoparticles and increases the active surface. A similar mechanism of activation surface occurs in the formation of bimetal nanoparticles for galvanic exchange.
  • Ti02 titanium target
  • the method according to the invention applied to a metal titanium target (Ti) can produce directly Ti02 nanoparticles , with waves at 1064 nm.
  • the oxidation of the ablated material is very quick and only a few nanoparticles of metal Ti can be observed.
  • Ti02 (Titania) is considered an effective catalyst, in particular in the Anatase crystalline form.
  • Nanoparticles of Ti02 can be generated, with said method, in a prevailing crystalline form, either Rutile or Anatase, simply changing the pulse energy.
  • the average diameter is 5 nm.
  • particles larger than 10 nm and with hollow structure can be produced.
  • the above described characteristics can be modulated by changing the diameter of the illuminated region between 0.5-5 mm, in particular 0.5-2 mm.
  • the palladium nanoparticles (Pd) can be generated with said method, at the wavelength of 1064 nm, in bi- distilled water where they are strongly oxidized and polydispersed with diameters of about 5-15 nm. The oxidation reduces the active surface and prevent their use in catalysis and hydrogen storage.
  • the Pd nanoparticles generated in 2-propanol, with the second harmonic at 532 nm of said picosecond laser have an average diameter of 2 nm and low dispersivity .
  • the metal Pd nanoparticles become largely dominating with respect to the of oxide PdO nanoparticles .
  • such nanoparticles are ideal for catalysis and hydrogen storage for their degree of purity and the big surface-volume ratio.
  • the metal Pd nanoparticles are steady for at least 4 months.
  • the concentration of Pd in the colloid can be controlled and calculated, from the value of the UV-Vis absorbance, after calibration by ICP.
  • the concentration of nanoparticles of magnetite can be controlled and calculated, from the value of the UV-Vis absorbance, after calibration by ICP.
  • the applications of said colloidal solutions range from the pharmaceutical industry, where the NPs can be used as carrier for detection of drugs (AuNP) or for making AgNP colloidal solutions as disinfectant, to the food industry, for example using the NPs in the packaging field for protecting the freshness of products in the packages, and to the agricultural industry, for example using the AgNPs for increasing the duration the cut flowers or as antiparasitic aid.
  • AuNP drugs
  • the NPs can be used as carrier for detection of drugs (AuNP) or for making AgNP colloidal solutions as disinfectant
  • the food industry for example using the NPs in the packaging field for protecting the freshness of products in the packages
  • the agricultural industry for example using the AgNPs for increasing the duration the cut flowers or as antiparasitic aid.

Abstract

L'invention concerne un procédé et un appareil de préparation de colloïdes constitués de nanoparticules métalliques, de métal ou d'oxyde métallique. Le procédé consiste à disposer au préalable une source (15) d'un faisceau laser (1) de Nd:YAG, présentant une durée d'impulsion comprise entre 15 et 40 picosecondes, une énergie d'impulsion comprise entre 2 et 100 mJ, à la longueur d'onde fondamentale de 1 064 nm ou à la deuxième harmonique de 532 nm ou à la troisième harmonique de 355 nm, et à une fréquence de répétition allant jusqu'à un maximum de 1 kHz dans la plage d'énergie pour l'impulsion. Ensuite, le procédé consiste à disposer au préalable une cible métallique (7) constituée de métal ou d'oxyde métallique dans un espace de travail (6) dans lequel est disposée ladite cible (7) immergée dans un solvant liquide (5). Une unité optique (11) est conçue pour dévier et concentrer le faisceau laser (1) émis par la source laser (10) sur la cible (7). La cible (7) est exposée à un rayonnement avec le faisceau laser (1), préparant ainsi un colloïde (14) des nanoparticules métalliques dans le solvant liquide (5). L'unité optique (11) expose la cible (7) à un rayonnement, le foyer (12) du faisceau laser (1) étant situé au-delà de la cible (7), de sorte que la cible (7) est exposée à un rayonnement dans une zone d'éclairage (13) de diamètre prédéfini qui est supérieur ou égal à 0,5 mm, afin de produire le colloïde (14) autour de la zone (13) avec une dimension, une distribution statistique et une concentration prédéfinie des nanoparticules.
PCT/IB2015/058901 2014-11-17 2015-11-17 Procédé de production de colloïdes comprenant des nanoparticules WO2016079681A1 (fr)

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Cited By (7)

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CN106077674A (zh) * 2016-06-16 2016-11-09 中国科学院合肥物质科学研究院 一种具有高效杀菌性能的银纳米颗粒胶体溶液
AT519146A1 (de) * 2016-10-05 2018-04-15 Univ Wien Tech Vorrichtung zur Analyse eines Feststoff-Probenmaterials
AT519146B1 (de) * 2016-10-05 2020-03-15 Univ Wien Tech Vorrichtung zur Analyse eines Feststoff-Probenmaterials
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CN106492715A (zh) * 2016-12-19 2017-03-15 广东工业大学 一种制备微粒的方法及装置
CN106492715B (zh) * 2016-12-19 2023-02-10 广东工业大学 一种制备微粒的方法及装置
CN112756938A (zh) * 2021-01-20 2021-05-07 深圳市鑫镭创科自动化科技有限公司 基于手机软件控制的双光束激光拆屏方法及装置
CN112756938B (zh) * 2021-01-20 2022-05-06 深圳市鑫镭创科自动化科技有限公司 基于手机软件控制的双光束激光拆屏方法及装置
CN114751649A (zh) * 2022-04-25 2022-07-15 哈尔滨工业大学 一种利用激光制备材料表面纳米颗粒的方法
CN114751649B (zh) * 2022-04-25 2023-08-25 哈尔滨工业大学 一种利用激光制备材料表面纳米颗粒的方法
CN115283684A (zh) * 2022-08-05 2022-11-04 大连理工大学 一种使用液相激光烧蚀法连续制备纳米颗粒的装置
CN115368894A (zh) * 2022-08-18 2022-11-22 北京科技大学 一种激光制备硫氧化物荧光粉的方法

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