A gallium-based probe, a preparation method thereof and application thereof in alkali metal ion detection

Abstract

The present application relates to a kind of gallium-based probes and its preparation method and application in alkali metal ion detection, belong to probe technical field.The present application uses the metal wire inside the honeycomb capillary as geometric template, removes metal wire completely by etching, obtains the hollow capillary with size defined by metal wire;The surface state of hollow capillary inner wall is regulated by gas phase silanization treatment, then high surface tension, low volatile metal gallium is injected under the condition of protective atmosphere, and metal gallium forms end face stable, calibratable and renewable ion functional working surface in geometrically controllable hollow channel, using the reversible alloying and dealloying reaction between gallium and alkali metal ion, the alkali metal ion concentration information is converted into the current, charge detection signal suitable for scanning electrochemical microscope, which can be quantitatively collected.

Description

Technical Field

[0001] This invention belongs to the field of probe technology, and particularly relates to a gallium-based probe, its preparation method, and its application in alkali metal ion detection. Background Technology

[0002] In mainstream battery systems such as lithium-ion and sodium-ion batteries, the transport behavior of alkali metal ions at the electrolyte phase and electrode interface has a decisive impact on battery capacity, rate performance, cycle life, and safety performance. Especially during the deposition and dissolution reactions of the metal anode, the transport and local concentration distribution of alkali metal ions at the interface significantly affect metal nucleation and deposition behavior, and are closely related to interface evolution processes such as non-uniform deposition, dendrite growth, and dead metal formation. Therefore, developing a technology that enables in-situ, quantitative, and high spatial resolution detection of alkali metal ions at the interface under real electrolyte conditions has extremely high research value and engineering significance for the performance optimization and technological iteration of various alkali metal batteries.

[0003] Currently, among the ion-sensitive scanning electrochemical microscope probes used for alkali metal ion detection, mercury-based probes utilize the reversible amalgamation fusion and stripping reaction between mercury and alkali metals to convert changes in alkali metal ion concentration into collectable current or charge signals, thus enabling effective ion concentration detection. However, mercury itself has drawbacks such as high toxicity, high volatility, and easy environmental pollution, placing stringent requirements on probe preparation processes, experimental procedures, and subsequent waste liquid treatment. Furthermore, existing mercury-based microprobes generally employ a method of electrodepositing mercury within a recessed structure at the tip of a locally etched solid metal probe. Relying on the recessed structure and interfacial forces to fix the mercury phase, under vertical operation or near-field scanning conditions, the mercury phase is highly susceptible to morphological distortion, loss, or even complete detachment due to factors such as gravity, external disturbances, and changes in interfacial wetting state.

[0004] Due to the poor stability of the mercury phase, existing mercury-based probes cannot be designed with large opening sizes, and the effective mercury phase volume is also greatly limited. This significantly reduces the probe's amalgamation working capacity and the detection range of alkali metal ion concentration, making it difficult to meet the actual needs of quantitative detection of high concentrations and wide ranges of alkali metal ions in battery organic electrolytes. Overall, the application limitations are quite prominent.

[0005] Compared to mercury, gallium has unique advantages such as low toxicity, low vapor pressure, excellent conductivity, injection molding capability, and high surface tension. It can also undergo reversible alloying and dealloying reactions with various alkali metals such as lithium, sodium, and potassium. Its material properties and detection principles are well-suited for alkali metal ion detection scenarios, making it an ideal material to replace mercury in the preparation of high-performance alkali metal ion detection probes. It has good potential for industrialization and scientific research applications.

[0006] However, current gallium microelectrodes are mainly fabricated using techniques such as tip-dipping gallium or direct infusion of gallium material into drawn glass capillaries. The probe tip size and microstructure are highly susceptible to the influence of drawing process parameters, making it impossible to guarantee the uniformity and stability of the effective working area of ​​different probes or the same probe at different stages of use. Furthermore, gallium readily forms dense surface oxide films in aqueous and oxygen-containing environments. After the probe completes its detection operation, its end face is easily covered by interfacial films and reaction byproducts, significantly altering the true active area and interfacial reaction state of the gallium electrode's working surface. This makes it difficult to establish a stable and repeatable alkali metal ion concentration calibration system for existing gallium probes, hindering accurate in-situ quantitative detection of alkali metal ions in organic electrolyte environments.

[0007] Based on this, the present invention is proposed. Summary of the Invention

[0008] Therefore, the technical problem to be solved by the present invention is to overcome the problems of poor controllability of the geometry of gallium-based probes, easy interference of the end face by oxide film, and difficulty in realizing quantitative detection of alkali metal ions in the prior art.

[0009] To address the aforementioned technical problems, this invention provides a gallium-based probe, its preparation method, and its application in alkali metal ion detection. The method uses a metal wire inside a honeycomb-shaped capillary as a geometric template. The metal wire is completely removed by etching, resulting in a hollow capillary whose dimensions are defined by the wire. The surface state of the inner wall of the hollow capillary is then controlled through vapor-phase silanization. Subsequently, gallium, with its high surface tension and low volatility, is injected under a protective atmosphere. This allows the gallium to form a stable, calibrable, and renewable ion functional working surface within the geometrically controllable hollow channel. The reversible alloying between gallium and alkali metal ions is then utilized. The dealloying reaction converts alkali metal ion concentration information into quantitative current and charge detection signals suitable for scanning electrochemical microscopy.

[0010] The first objective of this invention is to provide a method for preparing a gallium-based probe, comprising the following steps: S1. The insulating capillary is drawn to obtain a honeycomb-shaped capillary. S2. Insert a metal wire into the tail end of the honeycomb-shaped capillary described in S1, and let it fall to the needle tip area by gravity. After sealing, a composite capillary is obtained. S3. Grind and polish the tip area of ​​the composite capillary described in S2 until the internal metal wire is exposed to obtain a metal probe. S4. Remove the metal wire in the metal probe described in S3 by etching with an etching solution, and obtain a hollow capillary after washing and drying. S5. The hollow capillary described in S4 is subjected to gas-phase silanization treatment with a silanizing agent and dried to obtain a silanized composite capillary. S6. Under a protective atmosphere, metallic gallium is injected into the tail end of the silanized composite capillary described in S5 until the tip region is filled. A wire is then connected to the tail end and the capillary is encapsulated to obtain the gallium-based probe.

[0011] In one embodiment of the present invention, in S1, the insulating capillary is selected from a glass capillary or a quartz capillary.

[0012] In one embodiment of the present invention, in S2, the metal wire is selected from copper wire, gold wire, silver wire, platinum wire or nickel wire; And / or, the diameter of the metal wire is smaller than the inner diameter of the insulating capillary.

[0013] In one embodiment of the present invention, in S2, the sealing process involves first heating at 75°C-85°C for 28-32 seconds, and then continuing to heat under vacuum conditions for another 28-32 seconds.

[0014] In one embodiment of the present invention, in S3, the grinding and polishing is performed by sequentially grinding and polishing the needle tip area with diamond grinding material, diamond grinding material and silicon dioxide polishing material.

[0015] In one embodiment of the present invention, in S4, the concentration of FeCl3 in the etching solution is 1.2 mol / L-1.8 mol / L, and the concentration of HCl is 0.8 mol / L-1.2 mol / L.

[0016] In one embodiment of the present invention, in S5, the silanizing agent is selected from one or more of hexamethyldisilazane, trimethylchlorosilane, octadecyltrichlorosilane, methyltrimethoxysilane, and aminopropyltriethoxysilane. By regulating the surface energy of the inner wall of the glass through the silanizing agent, the wetting state between metallic gallium and the inner wall of the insulating capillary is changed, thereby enhancing the interface confinement effect of gallium in the hollow channel, improving the channel confinement effect and end face retention ability of liquid gallium, and suppressing irregular crawling of gallium along the inner wall of the glass, end face morphology fluctuations, and the shedding of the liquid metal phase at the front end.

[0017] In one embodiment of the present invention, in S5, the temperature of the gas phase silanization treatment is 50°C-70°C, and the time is 1h-3h.

[0018] A second objective of this invention is to provide a gallium-based probe prepared by the method described.

[0019] A third objective of this invention is to provide an application of the gallium-based probe in the detection of alkali metal ions; the gallium functional working surface of the gallium-based probe is capable of reversibly alloying with alkali metal ions. The dealloying reaction outputs a current or charge response related to ion concentration. After the probe is used, the gallium that has reacted or become contaminated at the front end can be pushed out of the channel by means of a syringe or pressure drive, so that the new gallium is exposed to the probe end face, thus realizing the renewal of the working surface.

[0020] The technical solution of the present invention has the following advantages compared with the prior art: (1) The gallium-based probe of the present invention uses a metal wire inside a honeycomb-shaped capillary as a geometric template. After etching to remove the metal wire, a hollow insulating microtube is formed. The size of the gallium working surface is limited by the diameter of the metal wire, which can obtain a geometrically controllable gallium working area with a regular end face morphology, effectively improving the consistency of preparation between different probes, and improving the reliability of quantitative calibration and the feasibility of electrochemical model analysis.

[0021] (2) In the preparation method of the present invention, before injecting metallic gallium into the hollow capillary, the hollow capillary is subjected to vapor-phase silanization treatment to regulate the surface energy of the inner wall of the capillary and the gallium content. The wetting state of the glass interface inhibits the irregular spreading, creeping, end-face morphology fluctuations, and shedding of the liquid metal phase at the front end of the gallium metal inside the microtube, thus stably confining the gallium metal within the hollow channel and facilitating the formation of a stable gallium working surface.

[0022] (3) The preparation method described in this invention completes the injection filling of metallic gallium under a protective atmosphere, which reduces the probability of gallium forming a dense oxide film and avoids the interference of the oxide film on the true active area of ​​the probe, the interface impedance and the alloying / dealloying response of alkali metal ions, thereby improving the quantitative detection performance of gallium-based probes for alkali metal ions.

[0023] (4) The gallium-based probe of the present invention relies on the structural features of the continuous gallium phase inside the hollow channel, and the probe end face can be updated in situ by means of syringe or pressure driving method. When the gallium working surface at the front end of the probe is covered by oxide film, interface film, electrolyte decomposition products or alloying reaction products, the gallium metal phase inside the hollow channel can be pushed to discharge the gallium that has been used at the tip, so that the new gallium is exposed at the tip of the probe, and the updated gallium working surface is obtained.

[0024] (5) The gallium-based probe of the present invention combines the geometrically controllable gallium working surface with the reversible alloying / dealloying reaction of alkali metal ions. The probe is no longer limited to serving as a common conductive microelectrode or a qualitative ion response element. Based on the calibration relationship established between peak current, deposited charge, stripped charge and ion concentration, in-situ quantitative detection of alkali metal ions such as lithium ions, sodium ions, and potassium ions can be achieved in organic battery electrolyte systems.

[0025] (6) The gallium-based probe of the present invention uses gallium, which has low toxicity, low vapor pressure, high conductivity and high surface tension, as the active metal phase. This reduces the risks of material toxicity, volatilization and environmental pollution, and also reduces the side reactions caused by the introduction of multi-metal components into the battery electrolyte, eliminating the uncertainty of signal attribution. Thanks to the excellent confinement effect of the geometrically controllable hollow channel treated with silanization on liquid gallium, the probe opening size is no longer strictly constrained by the problem of easy shedding of the liquid active phase, and a gallium working area with a larger diameter and larger effective volume can be constructed. Attached Figure Description

[0026] To make the content of this invention easier to understand, the invention will be further described in detail below with reference to specific embodiments and accompanying drawings, wherein: Figure 1 Microscopic images showing the overall morphology and cross-section of the metal probe, hollow glass capillary, and gallium-based probe of this invention. Figure 2 The figures show the cyclic voltammetry and approximation curves of the gallium-based probe of the present invention; wherein, the left figure is the cyclic voltammetry curve of the gallium-based probe in a non-aqueous electrolyte containing a reversible redox mediator, and the right figure is the scanning electrochemical microscope approximation curve of the gallium-based probe; Figure 3 The graphs show the cyclic voltammetric response and peak current-lithium ion concentration calibration relationship of the gallium-based probe in electrolytes with different bulk lithium ion concentrations. The left graph shows the cyclic voltammetric response curve of the gallium-based probe at different lithium ion concentrations, and the right graph shows the linear calibration relationship between the peak current and lithium ion concentration of the gallium-based probe. Figure 4 This is a graph showing the calibration relationship between different electrochemical signals of the gallium-based probe and lithium-ion concentration; the left graph shows the peak current. Lithium-ion concentration calibration curve, the middle graph shows the deposited charge. The lithium-ion concentration calibration curve, the right figure shows the stripped charge. Lithium-ion concentration calibration curve; Figure 5 The images show the actual object and concentration imaging of the gallium-based probe used for in-situ detection of alkali metal ions at the negative electrode interface of a battery according to the present invention. The left image is a physical image of the gallium-based probe performing in-situ detection at the negative electrode interface of a copper substrate, and the right image is a two-dimensional scanning imaging of the lithium ion concentration above the negative electrode interface during lithium deposition. Detailed Implementation

[0027] The present invention will be further described below with reference to the accompanying drawings and specific embodiments, so that those skilled in the art can better understand and implement the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. It should be understood that the specific embodiments are only used to explain the present invention, but the embodiments are not intended to limit the present invention.

[0028] In this invention, unless otherwise stated, the technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains.

[0029] In this invention, unless otherwise stated, the term "and / or" as used herein includes any and all combinations of one or more of the associated listed items.

[0030] In this invention, unless otherwise specified, the experimental methods used in the embodiments of this invention are conventional methods, and the materials and reagents used are commercially available unless otherwise specified.

[0031] In this invention, unless otherwise stated, the silicate glass capillary used in the embodiments is a silicate glass capillary with an outer diameter of 1.5 mm, an inner diameter of 0.5 mm, and a length of 100 mm.

[0032] In this invention, unless otherwise stated, the copper wire used in the embodiments has a diameter of 25 μm and a purity of 99.9%.

[0033] In this invention, unless otherwise stated, the purity of gallium used in the embodiments is 99.99%.

[0034] Example 1 Reference Figure 1 As shown, the gallium-based probe and its preparation method in this embodiment specifically include the following steps: S1. Take a glass capillary tube and clean it with acetone and deionized water for 20 minutes each. Then dry it thoroughly in an oven at 80℃ for later use. S2. Referring to Table 1, the glass capillary is installed on the HL-1000 programmable horizontal needle puller for pulling to obtain a honeycomb-shaped glass capillary. Table 1

[0035] S3. A copper wire is inserted into the end of a honeycomb-shaped glass capillary tube and falls to the bottom of the needle tip by gravity. The copper wire is then transferred to a vertical needle puller and the temperature is set to 80℃ for 30 seconds to soften the capillary tube and adhere it to the copper wire. The capillary tube is then heated again for 30 seconds under vacuum to seal the needle tip and then cooled naturally to obtain a composite glass capillary tube. S4. Fix the composite glass capillary to a precision grinding instrument, and successively grind and polish the tip of the composite electrode with 1μm diamond abrasive, 0.5μm diamond abrasive, and 0.02μm silica polishing material until the internal copper wire is exposed, thus obtaining a metal probe. S5. Dissolve FeCl3 and HCl in water to obtain an etching solution with FeCl3 concentration of 1.5 mol / L and HCl concentration of 1.0 mol / L. Place the metal probe in the etching solution to etch away all the copper wires. After etching, the hollow capillary obtained is ultrasonically cleaned with deionized water and acetone for 20 min each, and then dried at 80℃ for 2 h to obtain a hollow glass capillary. S6. Place the hollow glass capillary in a sealed desiccator, place hexamethyldisilazane at the bottom of the container, so that the hollow glass capillary is suspended above the reagent and does not come into direct contact with the reagent. Perform gas-phase silanization treatment at 60°C for 2 hours, and then dry at 80°C for 1 hour to obtain silanized composite glass capillary. S7. The silanized composite glass capillary is transferred into an argon atmosphere glove box with water and oxygen contents of ≤0.01ppm. A syringe is used to seal the end of the hollow glass microtube through a connecting tube. Positive pressure is applied by injecting gas. Under the combined action of pressure drive and capillary confinement, metallic gallium is caused to migrate towards the tip of the needle until a small amount of metallic gallium overflows from the tip. Then, a silver-plated copper wire is inserted into the end of the hollow glass microtube to achieve electrical conduction with the liquid gallium. Finally, it is encapsulated to obtain a gallium-based probe.

[0036] Test Example 1 Optical microscopy was used to characterize the metal probe, hollow glass capillary, and gallium-based probe, acquiring images of the overall morphology of the probe tip and its cross-sectional surface. The results are as follows: Figure 1 As shown. From Figure 1 It can be seen that the metal probe with a flat and smooth copper working surface, the hollow glass capillary, and the gallium-based probe have matching circular end face contours. The lateral dimension of the gallium working surface is limited by the original copper wire diameter. This indicates that by using the fabrication process of first preparing the composite glass capillary and then etching away the metal wire, the hollow channel of the hollow glass capillary can inherit the geometric dimensions of the metal wire. This structure provides a reliable structural basis for the consistent preparation, quantitative calibration, and end face renewal of the gallium working surface.

[0037] Test Example 2 Electrochemical performance verification and probe approach behavior testing of the gallium-based probe were performed. A three-electrode system was assembled using the gallium-based probe as the working electrode, a platinum wire as the counter electrode, and polypyrrole as the reference electrode. A propylene carbonate solution containing 5 mmol / L ethyl viologen bis(hexafluorophosphate) and 0.1 mol / L tetrabutylammonium hexafluorophosphate was used as the electrolyte, and the scan rate was set to 20 mV. s -1 At 2.7V-2.1V (vs. Li +Cyclic voltammetry was performed within the / Li) voltage window, and the cyclic voltammetry curves were recorded. Then, the gallium-based probe potential was set in the ethyl viologen diffusion control plateau region, and the gallium-based probe was slowly moved vertically towards the substrate. The normalized probe current was collected as a function of the probe-substrate normalized distance. The results are as follows: Figure 2 As shown. From Figure 2 As can be seen, the cyclic voltammogram yields a diffusion-controlled steady-state current response consistent with the characteristics of a micrometer-scale working electrode, confirming that the gallium working surface possesses good conductivity. This probe can be used as a scanning electrochemical microscope probe for electrochemical testing. In the approximation curve, when the normalized distance is large and the probe is far from the substrate surface, the normalized current remains relatively stable. When the normalized distance decreases and the probe approaches the substrate surface, the normalized current changes rapidly. This approximation curve can reflect the current change pattern when the probe approaches the substrate and can be used to determine the spatial distance between the probe end face and the substrate, providing a positioning basis for subsequent in-situ detection of the battery negative electrode interface.

[0038] Test Example 3 Lithium-ion quantitative calibration tests were performed on the gallium-based probe from Example 1. A three-electrode electrochemical testing system was constructed in an argon atmosphere glove box with water and oxygen contents both ≤0.01ppm. The gallium-based probe was used as the working electrode, platinum wire as the counter electrode, and polypyrrole as the quasi-reference electrode. LiPF6 standard electrolytes with lithium-ion concentrations of 0 mmol / L, 10 mmol / L, 20 mmol / L, 50 mmol / L, 75 mmol / L, and 100 mmol / L were prepared using propylene carbonate as the solvent and 100 mmol / L tetrabutylammonium hexafluorophosphate as the supporting electrolyte. Before testing, the probe was subjected to cyclic voltammetry pre-cycling until the peak shape stabilized. The scan potential was set to 2.50V-0.10V (vs. Li). + / Li), with a scan rate of 0.10 V / s, cyclic voltammetry tests were performed on standard electrolytes with different lithium-ion concentrations. The dealloying peak current signal was extracted and the blank background corresponding to 0 mmol / L electrolyte was subtracted. Linear fitting was performed with lithium-ion concentration as the x-axis and the corrected peak current as the y-axis. The results are as follows: Figure 3 As shown. From Figure 3 It can be seen that as the concentration of lithium ions in the electrolyte increases, the absolute value of the peak current of the alloying reduction peak gradually increases. The peak shapes of the voltammetric curves corresponding to different concentrations are complete and distinguishable. At the same time, the peak current of the probe and the concentration of lithium ions in the electrolyte show a good linear correspondence. This proves that the gallium-based probe can use the alloying response signal to feedback the concentration of lithium ions in the electrolyte and has the ability to quantitatively detect lithium ions in the concentration range of 0-100 mmol / L.

[0039] Test Example 4 Cyclic voltammetry was performed using the same potential window and scan rate as in Test Example 3. The response signals for peak current, deposited charge, and stripped charge were extracted. Signal correction was performed using the response of 0 mmol / L LiPF6 electrolyte as a blank background. Linear fitting was performed with the corrected peak current, deposited charge, and stripped charge as the ordinate, with the lithium ion concentration as the x-axis. The results are shown below. Figure 4 As shown. From Figure 4 It can be seen that the deposition charge, stripping charge, and peak current of the gallium-based probe all increase linearly with the increase of the lithium ion concentration. All three electrochemical signals have a good linear correlation with the lithium ion concentration and can be used to construct a quantitative calibration curve for lithium ions.

[0040] Test Example 5 A four-electrode in-situ detection system was constructed, using the gallium-based probe from Example 1 as the working electrode, a copper substrate as the base electrode, a platinum wire as the counter electrode, and polypyrrole as the reference electrode. A propylene carbonate solution containing 0.1 mol / L lithium hexafluorophosphate and 0.1 mol / L tetrabutylammonium hexafluorophosphate was used as the electrolyte. An epoxy resin-covered area and an exposed copper area were formed on the surface of the copper substrate. The epoxy resin-covered area suppressed interfacial electrochemical reactions, while the exposed copper area served as the lithium deposition reaction region. First, the gallium-based probe was tested in an electrolyte containing a reversible redox mediator to obtain an approximation curve, thereby determining the detection height between the probe and the substrate. The gallium-based probe was controlled to maintain this detection height, and the probe was moved to the area above the epoxy resin-covered area, the exposed copper area, and the interface between the two. A potential that allows lithium-ion reduction deposition was applied to the copper substrate. During the lithium deposition process, the alloying peak current signal corresponding to different positions of the probe was collected, and combined with the previously established peak current... The local lithium-ion concentration at each location was obtained by converting the lithium-ion concentration calibration relationship, and a two-dimensional imaging of the lithium-ion concentration above the negative electrode interface was completed. The results are as follows: Figure 5 As shown. From Figure 5 As can be seen, the two-dimensional concentration imaging results show obvious spatial concentration differences. The peak current intensity is different at different locations, and the color depth in the imaging image represents the lithium ion concentration. It can intuitively reflect the spatial distribution characteristics of lithium ion concentration above the negative electrode interface during the lithium deposition process.

[0041] Obviously, the above embodiments are merely illustrative examples for clear explanation and are not intended to limit the implementation. Those skilled in the art will recognize that other variations or modifications can be made based on the above description. It is neither necessary nor possible to exhaustively list all possible implementations here. However, obvious variations or modifications derived therefrom are still within the scope of protection of this invention.

Claims

1. A method for preparing a gallium-based probe, characterized in that, Includes the following steps: S1. The insulating capillary is drawn to obtain a honeycomb-shaped capillary. S2. Insert a metal wire into the tail end of the honeycomb-shaped capillary described in S1, and let it fall to the needle tip area by gravity. After sealing, a composite capillary is obtained. S3. Grind and polish the tip area of ​​the composite capillary described in S2 until the internal metal wire is exposed to obtain a metal probe. S4. Remove the metal wire in the metal probe described in S3 by etching with an etching solution, and obtain a hollow capillary after washing and drying. S5. The hollow capillary described in S4 is subjected to gas-phase silanization treatment with a silanizing agent and dried to obtain a silanized composite capillary. S6. Under a protective atmosphere, metallic gallium is injected into the tail end of the silanized composite capillary described in S5 until the tip region is filled. A wire is then connected to the tail end and the capillary is encapsulated to obtain the gallium-based probe.

2. The method for preparing a gallium-based probe according to claim 1, characterized in that, In S1, the insulating capillary is selected from glass capillary or quartz capillary.

3. The method for preparing a gallium-based probe according to claim 1, characterized in that, In S2, the metal wire is selected from copper wire, gold wire, silver wire, platinum wire, or nickel wire; And / or, the diameter of the metal wire is smaller than the inner diameter of the insulating capillary.

4. The method for preparing a gallium-based probe according to claim 1, characterized in that, In S2, the sealing process involves first heating at 75°C-85°C for 28-32 seconds, and then continuing heating under vacuum conditions for another 28-32 seconds.

5. The method for preparing a gallium-based probe according to claim 1, characterized in that, In S3, the grinding and polishing involves sequentially grinding and polishing the needle tip area with diamond grinding material, diamond grinding material, and silicon dioxide polishing material.

6. The method for preparing a gallium-based probe according to claim 1, characterized in that, In S4, the concentration of FeCl3 in the etching solution is 1.2 mol / L-1.8 mol / L, and the concentration of HCl is 0.8 mol / L-1.2 mol / L.

7. The method for preparing a gallium-based probe according to claim 1, characterized in that, In S5, the silanizing agent is selected from one or more of hexamethyldisilazane, trimethylchlorosilane, octadecyltrichlorosilane, methyltrimethoxysilane, and aminopropyltriethoxysilane.

8. The method for preparing a gallium-based probe according to claim 1, characterized in that, In S5, the temperature of the gas-phase silanization treatment is 50℃-70℃, and the time is 1h-3h.

9. A gallium-based probe prepared by the method of any one of claims 1-8.

10. The application of the gallium-based probe as described in claim 9 in the detection of alkali metal ions.

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