A single-particle particle size measurement method based on liquid / liquid interface ion transfer shielding effect
By utilizing the ion transfer shielding effect at the liquid/liquid interface, the particle size of nanoparticles is measured through particle collisions within micro/nano glass tubes. This overcomes the limitations of traditional methods, enabling efficient and accurate measurement of conductor, semiconductor, and insulator particles, and expanding the measurement range.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- SUN YAT SEN UNIV
- Filing Date
- 2023-06-27
- Publication Date
- 2026-05-01
AI Technical Summary
Existing technologies have limitations in measuring the size of individual micro and nanoparticles, especially the cumbersome pretreatment and poor reproducibility of traditional solid-state microelectrodes. Furthermore, the liquid/liquid interface is a single research object, and the measurement signal mainly comes from ion transfer caused by the collision of droplets with the interface, lacking effective single-particle characterization methods.
A method based on the ion transfer shielding effect at the liquid/liquid interface was adopted. The particle size was measured by the ion transfer changes in nanoparticles and the interface within a micro/nano glass tube. The current shielding effect was analyzed using an Ag/AgCl electrode and a CHI electrochemical workstation in combination with a specific solution system.
It improves the accuracy and reliability of nanoparticle size measurement, expands the range of measurable particles, including conductors, semiconductors and insulators, reduces charging current and ohmic loss, enhances the effect of diffusion, and is applicable to a variety of nanoparticle types.
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Figure CN116773424B_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of electrochemistry, and specifically to a method for measuring the particle size of a single particle based on the ion transfer shielding effect at the liquid / liquid interface. Background Technology
[0002] Spectroscopy, including single-molecule fluorescence microscopy, infrared nanospectroscopy, localized surface plasmon resonance, and Raman spectroscopy, has become a primary method for studying single molecules and nanoparticles. However, spectroscopic methods are often limited by chemoselectivity (e.g., limitation to specific molecules) or spatial resolution (e.g., diffraction limit). Therefore, electrochemical methods are being developed as an alternative / supplementary technique for studying single particles, such as scanning electrochemical microscopy (SECM) or scanning electrochemical cell microscopy (SECCM). Given the wide range of applications of electrochemistry in the study of nanostructured materials, its applications range from batteries and electrocatalysis to biochemical sensing.
[0003] Monomer collision electrochemistry (SECE) has become an important branch of modern electroanalytical chemistry, providing us with a wealth of useful information, such as the size, concentration, and catalytic reaction process (structure-function relationship) of individual hard or soft particles. This technique has been widely applied to various analytes, from organic / inorganic nanoparticles, macromolecules such as DNA and proteins, to complex biological entities such as viruses, vesicles, and cells. In 2004, Lemay et al. first reported the discrete adsorption of 1 μm diameter carboxylate-stabilized latex microspheres and 25 nm diameter carboxylated CdSe quantum dot nanoparticles on solid-state ultramicroelectrodes, pioneering SECE based on the "shielding effect" of electron transfer as an indicator reaction (BM Quinn, PG van't Hof, SGLemay. Time-Resolved Electrochemical Detection of Discrete Adsorption Events. J. Am. Chem. Soc. 2004, 126, 8360–8361). Subsequently, more scholars have used the collision of single particles with traditional solid-state microelectrodes to obtain changes in electrical signals to characterize information such as particle size and concentration. However, the cumbersome electrode pretreatment and relatively poor reproducibility have limited its practical application. Liquid / liquid interfaces, on the other hand, have advantages such as molecular-level smoothness, ease of preparation, and good reproducibility, and are expected to complement traditional solid-state electrodes as another ideal platform for single-particle collision measurements.
[0004] In summary, when using solid-state microelectrodes for SECE via the "shielding effect" mode, the analyte is limited to insulator particles. Meanwhile, SECE work based on micro / nano liquid / liquid interfaces primarily focuses on soft particles—droplets (work on Faraday counters and plasmas can also be broadly categorized into this type). The research object is singular, and the measured electrical signals mainly originate from ion or accelerated ion transfer signals during collisions between (single, multiple, or aggregated) droplets and the micro / nano liquid / liquid interface. Therefore, developing techniques for characterizing individual micro / nano-scale particles at the liquid / liquid interface is essential for understanding and further fine-tuning particle properties. Summary of the Invention
[0005] To overcome the shortcomings of the prior art, the present invention provides a method for measuring the particle size of a single particle based on the ion transfer shielding effect at the liquid / liquid interface.
[0006] To achieve the above objectives, the technical solution adopted by the present invention is as follows:
[0007] A method for measuring the size of a single particle based on the ion transfer shielding effect at the liquid / liquid interface includes the following steps:
[0008] (1) The capillary glass tube was immersed in the piranha solution, then the capillary glass tube was soaked and rinsed with water, dried and then drawn to obtain the micro-nano glass tube.
[0009] (2) Fill the micro-nano glass tube with an aqueous solution, insert the Ag / AgCl electrode into it, and then insert the micro-nano glass tube and the counter / reference electrode into an electrolytic cell containing an oil solution. Then place the electrolytic cell in a shielded box, start the CHI electrochemical workstation, and measure the steady-state current before the collision.
[0010] (3) Add the particles to be tested to the aqueous solution, then repeat step (2), measure the steady-state current after the collision, and obtain the particle size according to the following formula: In the formula, r p R represents the radius of the particle to be measured. pipet Indicates the inner diameter of the micro / nano glass tube described in step (1), i ss The steady-state current before the collision, Δi ss This represents the difference between the steady-state current after the collision and the steady-state current before the collision, i.e., the height of the drop in step current during the shielded collision experiment.
[0011] The aqueous phase solution contains at least one of chlorides and at least one of lithium salts; the lithium salt is at least one of lithium perchlorate and lithium tetrafluoroborate; the oil phase solution is a trifluorotoluene solution containing ammonium bis(triphenylphosphine)tetra(pentafluorophenyl)borate.
[0012] Preferably, in step (1), the capillary glass tube is immersed in the piranha solution for 0.8-1.2 hours.
[0013] Preferably, in step (1), the water soaking is done with ultrapure water.
[0014] Preferably, in step (1), the soaking time in water is ≥12h.
[0015] In step (1) of this invention, the capillary glass tube is soaked and rinsed with water, and the pH of the capillary glass tube after rinsing is in the neutral range after soaking in water for 2 minutes.
[0016] Preferably, in step (1), the ratio of the inner diameter of the micro-nano glass tube to the particle size to be measured follows the rule of thumb of one-tenth: inner diameter of micro-nano glass tube / particle size to be measured ≤ 10:1; if the inner diameter of the glass tube is 250-350nm, then particles with a diameter ≥ 25-35nm can be measured.
[0017] Preferably, in steps (2) and (3), when testing the steady-state current before and after the collision, the potential of the steady-state current region of -0.18V to -0.4V is selected as the potential of the current shielding region.
[0018] Preferably, the particles to be tested in step (3) include at least one of conductor particles, semiconductor particles, and insulator particles; more preferably, the conductor particles include gold nanoparticles and platinum nanoparticles; the semiconductor particles include titanium dioxide; and the insulator particles include silicon dioxide and polystyrene microspheres.
[0019] Preferably, the chloride is at least one selected from lithium chloride, hydrogen chloride, sodium chloride, and magnesium chloride; more preferably, the chloride is lithium chloride.
[0020] Preferably, the chloride concentration is 8-12 mmol / L; more preferably, the chloride concentration is 9-11 mmol / L.
[0021] Preferably, the lithium salt is lithium perchlorate.
[0022] Preferably, the lithium salt concentration is 8-12 mmol / L; more preferably, the lithium salt concentration is 9-11 mmol / L.
[0023] In some specific embodiments of the present invention, a 100 mmol / L lithium salt and a 100 mmol / L chloride aqueous solution can be prepared first, and diluted as needed before use.
[0024] Preferably, the oil phase solution contains 4-6 mmol / L ammonium bis(triphenylphosphine)tetra(pentafluorophenyl)borate; more preferably, the oil phase solution contains 4.5-5.5 mmol / L ammonium bis(triphenylphosphine)tetra(pentafluorophenyl)borate.
[0025] Compared with the prior art, the beneficial effects of the present invention are:
[0026] This invention employs a micro / nano liquid / liquid interface two-electrode system, utilizing two-phase ion transfer as an indicator reaction to achieve single-particle shielding effect collisional electrochemistry. When nanoparticles in an aqueous solution within a micro / nano glass tube randomly collide with the interface, a portion of the liquid / liquid interface region is occupied, thus partially blocking ion transfer. At this point, setting a potential within the diffusion-limited steady-state ion transfer current region allows for the observation of a reduced step current signal (e.g., ...) in the it plot. Figure 1 The method of this invention significantly reduces charging current and high ohmic drop of organic solvents at the liquid / liquid interface supported by micro / nano glass tubes. Furthermore, since the analyte is located inside the tube, and ions in the solution diffuse primarily via semi-infinite linear diffusion, they are less affected by the radial distribution of diffusion flux. Due to the reduced "edge effect," the accuracy of nanoparticle size measurement is greatly improved. This invention expands the measurable particle range of traditional shielding-effect collisional electrochemistry, which uses solid / liquid interface electron transfer as an indicator reaction, to include not only insulator particles but also conductor and semiconductor particles. Attached Figure Description
[0027] Figure 1 This is a diagram illustrating the shielding effect during ion transfer.
[0028] Figure 2 The image shows the current-time curve and detailed magnification of the shielding effect at the w / TFT interface after adding 10 pM platinum nanoparticles in Example 1.
[0029] Figure 3 In Example 1, the particle size distribution of 10 pM platinum nanoparticles in deionized water and 10 mM LiCl + 10 mM LiClO4 aqueous solution was measured using dynamic light scattering (DLS), and the particle size distribution of 10 pM platinum nanoparticles in 10 mM LiCl + 10 mM LiClO4 aqueous solution was calculated using the shielding effect.
[0030] Figure 4 The current-time curve and detailed magnified image of the shielding effect at the w / TFT interface after adding 1pM gold nanoparticles in Example 2;
[0031] Figure 5In Example 2, the particle size distribution of 1 pM gold nanoparticles in deionized water and 10 mM LiCl + 10 mM LiClO4 aqueous solution was measured using DLS, and the particle size distribution of 1 pM gold nanoparticles in 10 mM LiCl + 10 mM LiClO4 aqueous solution was calculated using the shielding effect.
[0032] Figure 6 The current-time curve and detailed magnified image of the shielding effect at the w / TFT interface after adding 500pM silica microspheres in Example 3;
[0033] Figure 7 In Example 3, the particle size distribution of 500 pM silica microspheres in a 10 mM LiCl + 10 mM LiClO4 aqueous solution was measured using DLS, and the particle size distribution of 500 pM silica microspheres in a 10 mM LiCl + 10 mM LiClO4 aqueous solution was calculated using the shielding effect. Detailed Implementation
[0034] The specific embodiments of the present invention will be further described below. It should be noted that these descriptions are for the purpose of aiding understanding the present invention, but do not constitute a limitation thereof. Furthermore, the technical features involved in the various embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.
[0035] Unless otherwise specified, the experimental methods used in the following embodiments are conventional methods, and the experimental materials used in the following embodiments are all available through conventional commercial channels.
[0036] Example 1
[0037] Current shielding effect of platinum nanoparticles
[0038] 1. Cleaning, preparation and characterization of micro / nano glass tubes
[0039] First, the borosilicate glass capillary was immersed in a piranha solution for one hour, then placed in a beaker filled with ultrapure water and immersed for more than twelve hours. Afterward, the glass capillary was removed and its inner and outer walls were rinsed with a large amount of ultrapure water. The rinsed glass capillary was placed in a clean 500mL beaker filled with ultrapure water and immersed for 2 minutes. The pH of the water was then tested with pH paper to ensure it was within the neutral range. If not, the glass capillary was rinsed with ultrapure water repeatedly until the pH value met the requirements. Finally, it was dried in an oven for later use. The glass tubes were drawn using a PC-100 programmable vertical glass tube drawing machine (PC-100 drawing machine). First, the drawing was performed according to the parameters set in the process. Then, the tube diameter was measured and recorded using a digital optical microscope or scanning electron microscope before being placed in an electrode box for later use. The inner diameter of the micro / nano glass tubes used in this experiment was 250-350nm.
[0040] 2. Synthesis of the oil-phase electrolyte bis(triphenylphosphine)tetra(pentafluorophenyl)borate ammonium (BATB)
[0041] The method for preparing BATB is as follows: First, weigh 3.2674 g of the bis(triphenylphosphine)tetra(pentafluorophenyl)borate lithium diethyl ether complex (LiTB·2.5C4H) into two beakers. 10 O) and 2.1526 g of bis(triphenylphosphine)ammonium chloride (BACl) solid powder were both added to 75 mL of a methanol-deionized water solution (50 mL methanol, 25 mL deionized water, volume ratio 2:1). After complete dissolution, the solution containing LiTB·2.5C4H was added using a clean glass dropper. 10 One droplet of O in a methanol-water solution is added dropwise to another beaker containing a methanol-water solution of BACl. A double displacement reaction occurs, and the reaction can be accelerated by continuous stirring with a glass rod. After the addition is complete, the mixture can be left to stand overnight to increase the yield. The product is then transferred to a vacuum filtration flask and filtered through an organic membrane. Simultaneously, excess lithium chloride is dissolved in ultrapure water. The crude product obtained on the organic membrane is dried in an oven. Next, the crude product is purified by recrystallization using pure acetone, maintaining an oil bath temperature of 50–60°C. The acetone is added dropwise until complete dissolution and recrystallization takes 20 minutes. The container is then sealed with sealing film, and crystals will precipitate at room temperature. The container is then refrigerated at 4°C overnight. Finally, BATB is washed with plenty of deionized water to obtain higher purity BATB. The final product is transferred to a clean sample vial and dried in a desiccator for storage.
[0042] 3. Preparation of aqueous and organic phase solutions
[0043] The aqueous phase solution is a lithium chloride + lithium perchlorate solution, and the organic phase solution is a 5 mM bis(triphenylphosphine)tetra(pentafluorophenyl)borate (BATB) trifluorotoluene solution. Preparation method of lithium chloride + lithium perchlorate solution: Weigh 0.106 g of lithium perchlorate solid powder and 0.042 g of lithium chloride solid powder into separate sample vials, add 10 mL of deionized water to dissolve, tighten the vials, seal with sealing film, and vortex vigorously for 30 s to obtain 100 mM lithium chloride and 100 mM lithium perchlorate aqueous solutions. Dilute according to requirements when different concentration gradients are needed. When preparing an aqueous phase solution containing water-soluble nanoparticles, considering that transition metal nanoparticles may aggregate due to excessively high ion concentrations in the aqueous phase solution, prepare an ion solution of appropriate concentration first, and then add the nanoparticle solution to the solution using a pipette. Preparation of 5 mM BATB trifluorotoluene solution: Weigh 0.0304 g of bis(triphenylphosphine)tetra(pentafluorophenyl)borate ammonium (BATB) into a sample vial, add 5 mL of trifluorotoluene to dissolve it, tighten the cap, seal with sealing film, place in a vortex mixer and vortex vigorously for 30 seconds, then let stand until ready for use. The preparation of other organic phase solutions is similar.
[0044] 4. Construction of liquid / liquid interfaces
[0045] The Ag / AgCl electrode was rinsed with ultrapure water and then carefully wiped with lint-free paper (avoiding scraping off AgCl powder). Aqueous solution was poured into the micro / nano glass tube using a syringe with a micro-needle (ensuring no air bubbles), and the Ag / AgCl working electrode was inserted into it. The micro / nano glass tube and the counter / reference electrode were then inserted into an electrolytic cell containing organic solution. The electrolytic cell was then placed in an ultra-micro current shielded box, and the CHI electrochemical workstation was started with parameters set for the experiment. After completing a scan of one electrolytic cell, the aqueous solution was replaced, and the above steps were repeated.
[0046] 5. Selection of collision potential
[0047] Cyclic voltammetry was first performed using a 10 mM lithium chloride + 10 mM lithium perchlorate aqueous solution as the aqueous phase and a trifluorotoluene solution as the organic phase as the research system. A steady-state current plateau of -0.18 V to -0.4 V was selected from the cyclic voltammogram as the current shielding region, corresponding to a current of approximately -70 pA. A higher steady-state current is beneficial for resolving collision signals. In the negative potential region of the potential window, perchlorate ions migrate from the aqueous phase to the oil phase. Negatively charged nanoparticles were selected along the electric field direction of the double layer, and the particles moved towards the interface along the direction of the electric field. Furthermore, the current-time curve and detailed magnified image of the shielding effect at the w / TFT interface after adding 10 pM platinum nanoparticles are shown below. Figure 2 As shown, a constant voltage of -0.25V is applied, and the tube diameter is 270nm.
[0048] 6. Data processing and analysis
[0049] In previous research by Professor Bard's group, it was found that Δi ss With steady-state current i ss The ratio is equal to the radius r of the microelectrode. UME The square of the number of particles and the radius of the circle projected onto the electrode surface (r) p The ratio of the squares of (references: Dick, JE; Renault, C.; Bard, AJ, Observation of Single-Protein and DNA Macromolecule Collisions on Ultramicroelectrodes. J. Am. Chem. Soc. 2015, 137, 8376-8379). Therefore, the inner radius (r) of the glass tube electrode is known. pipet ), the change in steady-state current before and after the collision (Δi) ss ) and the steady-state current value before the collision (i ss From this, we can obtain a simple expression for the radius of the colliding particles: This invention utilizes the shielding effect to calculate the particle size distribution of 10 pM platinum nanoparticles in a 10 mM LiCl + 10 mM LiClO4 aqueous solution, such as... Figure 3 The bar chart is shown. The comparison results of DLS of this sample in deionized water and 10mM LiCl + 10mM LiClO4 aqueous solution are also shown. Figure 3 DLS measurements showed that the particle size of platinum nanoparticles in deionized water was mainly in the range of 50–60 nm, with a dispersibility index (PDI) of 0.066, consistent with the parameters at the time of purchase. However, when platinum nanoparticles were dispersed in a 10 mM LiCl + 10 mM LiClO4 solution, the particle size was mainly distributed in the range of 120–500 nm. This is because in ionic solutions, due to chemically induced instability and the interaction of electrostatic bilayers and van der Waals forces between particles, the particle size of platinum nanoparticles increases significantly. The particle size of platinum nanoparticles calculated using formula (1) based on a single current step obtained by the shielding effect was mainly distributed between 60 and 300 nm. Considering that the electrochemical collision experiment and the sample preparation time for DLS characterization are not completely consistent, there is a certain error. However, the measurement of the particle size of a single particle using the ion current shielding effect still has a certain reference value.
[0050] Example 2
[0051] Current shielding effect of gold nanoparticles
[0052] The specific experimental steps are the same as in Example 1, except that platinum nanoparticles are replaced with gold nanoparticles. Data processing and analysis are as follows:
[0053] The current-time curve and its detailed magnified image of the shielding effect at the w / TFT interface after adding 1pM gold nanoparticles are shown below. Figure 4 As shown, a constant voltage of -0.25V is applied, and the tube diameter is 300nm.
[0054] like Figure 5 As shown, the particle size distribution of 1 pM gold nanoparticles in deionized water and 10 mM LiCl + 10 mM LiClO4 aqueous solution was measured using DLS, and the particle size distribution of 1 pM gold nanoparticles in 10 mM LiCl + 10 mM LiClO4 aqueous solution was calculated using the shielding effect. DLS measurements showed that the particle size of gold nanoparticles in deionized water was mostly concentrated in the range of 10 nm to 50 nm, with a dispersibility index (PDI) of 0.2536, less than 0.3, indicating good colloidal stability of the gold nanoparticles. In the experiment, the colloidal solution of gold nanoparticles was diluted to obtain an aqueous solution of 10 mM LiCl + 10 mM LiClO4 + 1 pM gold nanoparticles before DLS testing. At this time, the particle size of the gold nanoparticles in the solution was mainly distributed in the range of 70–200 nm, with a dispersibility index (PDI) of 0.475. The particle size of the gold nanoparticles calculated using formula (1) based on a single current step obtained using the shielding effect was mainly distributed between 70 and 300 nm. It can be seen that the addition of lithium chloride and lithium perchlorate affects the dispersibility of gold nanoparticles and leads to a certain degree of aggregation, but the results of the ion current shielding effect are basically consistent with the results of dynamic light scattering measurement.
[0055] Example 3
[0056] Current shielding effect of silica microspheres
[0057] The specific experimental steps are the same as in Example 1, except that platinum nanoparticles are replaced with silica microspheres. Data processing and analysis are as follows:
[0058] Unlike platinum and gold nanoparticles, which are derived from stable colloidal solutions, silica microspheres are difficult to disperse in aqueous solutions and tend to settle at the bottom, forming large particles. Therefore, a higher particle concentration was chosen when preparing the silica microsphere solution, followed by sonication, settling, and further dilution of the supernatant. The current-time curve and detailed magnified image of the shielding effect at the w / TFT interface after adding 500 pM silica microspheres are shown below. Figure 6 As shown, a constant voltage of -0.25V is applied, and the tube diameter is 300nm.
[0059] like Figure 7As shown, the particle size distribution of 500 pM silica microspheres in a 10 mM LiCl + 10 mM LiClO4 aqueous solution was measured using DLS, and the particle size distribution of 500 pM silica microspheres in a 10 mM LiCl + 10 mM LiClO4 aqueous solution was calculated using the shielding effect. The particle size of silica microspheres in deionized water measured by DLS was mainly concentrated between 70 and 200 nm. The particle size was mainly distributed between 50 and 230 nm according to the single current step obtained by the ion current shielding effect and calculated using formula (1). Under the same solution conditions, the DLS results were used as a control, and it can be seen that the first peak is basically consistent with the calculation results of the ion current shielding effect. Considering that the ion current shielding effect is carried out in a 300 nm glass tube for collision experiments, while the DLS characterization uses a large-capacity (mL-level) cuvette, the second intensity peak in the DLS results may be caused by the sedimentation of silica microspheres in the solution.
[0060] The embodiments of the present invention have been described in detail above, but the present invention is not limited to the described embodiments. For those skilled in the art, various changes, modifications, substitutions, and variations can be made to these embodiments without departing from the principles and spirit of the present invention, and these variations still fall within the protection scope of the present invention.
Claims
1. A method for measuring the particle size of a single particle based on the ion transfer shielding effect at the liquid / liquid interface, characterized in that, Includes the following steps: (1) The capillary glass tube was immersed in the piranha solution, then the capillary glass tube was soaked and rinsed with water, dried and then drawn to obtain the micro-nano glass tube. (2) Fill the micro-nano glass tube with an aqueous solution, insert the Ag / AgCl electrode into it, and then insert the micro-nano glass tube and the counter / reference electrode into an electrolytic cell containing an oil solution. Then place the electrolytic cell in a shielded box, start the CHI electrochemical workstation, and measure the steady-state current before the collision. (3) Add the test particles to the aqueous solution, wherein the test particles include at least one of conductor particles, semiconductor particles and insulator particles; then repeat step (2) to measure the steady-state current after the collision, and obtain the particle size according to the following formula: In the formula, r p R represents the radius of the particle to be measured. pipet Indicates the inner diameter of the micro / nano glass tube described in step (1), i ss The steady-state current before the collision, Δi ss The difference between the steady-state current after the collision and the steady-state current before the collision is represented by the height of the step current drop in the shielded collision experiment; the ratio of the inner diameter of the micro-nano glass tube to the particle size to be measured follows the one-tenth empirical rule, and the ratio of the inner diameter of the micro-nano glass tube to the particle size to be measured is ≤10:
1. In steps (2) and (3), when testing the steady-state current before and after the collision, the potential of the steady-state current region of –0.18 V ~ –0.4 V is selected as the potential of the current shielding region. The aqueous phase solution contains at least one of chlorides and at least one of lithium salts; the lithium salt is at least one of lithium perchlorate and lithium tetrafluoroborate; the oil phase solution is a trifluorotoluene solution containing ammonium bis(triphenylphosphine)tetra(pentafluorophenyl)borate.
2. The single-particle size measurement method based on the ion transfer shielding effect at the liquid / liquid interface according to claim 1, characterized in that, In step (1), the capillary glass tube is immersed in the piranha solution for 0.8-1.2 h.
3. The single-particle size measurement method based on the ion transfer shielding effect at the liquid / liquid interface according to claim 1, characterized in that, In step (1), the soaking time in water is ≥12 h.
4. The single-particle size measurement method based on the ion transfer shielding effect at the liquid / liquid interface according to claim 1, characterized in that, The conductor particles include gold nanoparticles and platinum nanoparticles; the semiconductor particles include titanium dioxide; and the insulator particles include silicon dioxide and polystyrene microspheres.
5. The single-particle size measurement method based on the ion transfer shielding effect at the liquid / liquid interface according to claim 1, characterized in that, The chloride is at least one of lithium chloride, hydrogen chloride, sodium chloride, and magnesium chloride; the concentration of the chloride is 8-12 mmol / L.
6. The single-particle size measurement method based on the ion transfer shielding effect at the liquid / liquid interface according to claim 1, characterized in that, The lithium salt concentration is 8-12 mmol / L.
7. The single-particle size measurement method based on the ion transfer shielding effect at the liquid / liquid interface according to claim 1, characterized in that, The oil phase solution contains 4-6 mmol / L of ammonium bis(triphenylphosphine)tetra(pentafluorophenyl)borate.