In-situ electrolytic cell device for measuring molecular force spectra at solid-liquid interfaces using an atomic force microscope

Abstract

The present invention discloses an atomic force microscope in-situ electrolytic cell device for measuring the molecular force spectrum of a solid-liquid interface. The structure includes a working electrode, a reference electrode, a counter electrode, and an electrolytic cell. The cell body is sequentially composed of an optical glass window, a flange top cover, a Teflon substrate, a sealing ring, a metal sample support sheet, a central through-hole Teflon support sheet, a magnetic coil plate, a spring gasket, and a flange base from top to bottom. The center of the Teflon substrate is provided with an opening, and the top is sequentially fixed with a flange top cover and an optical glass window from bottom to top. The bottom is respectively composed of a sealing ring, a metal sample support sheet, a central through-hole Teflon support sheet, a magnetic coil plate, and a flange base from top to bottom. An external signal source drives the magnetic coil, and the interaction between the magnetic probe and the molecular / ion clusters inside the interface double layer is used to realize sub-nanometer real-space imaging of the solid-liquid interface structure in the electrochemical process. The present invention can assist in the needs of material electrochemical testing and atomic force microscope data acquisition.

Description

Technical Field

[0001] The invention relates to the technical field of electrochemistry, in particular to an atomic force microscope in-situ electrolytic cell device for measuring solid-liquid interface molecular force spectrum. Background Art

[0002] Molecular force spectroscopy techniques for solid-liquid interfaces include atomic force microscopy (AFM), surface force instrumentation (SFA), quartz crystal microbalance (QCM), optical tweezers, and confocal Raman microscopy (Confocal Raman Microscopy). Each method has its own advantages and limitations. SFA precisely measures the forces between two surfaces and is suitable for liquid media, but is limited by surface parallelism and transparency requirements. QCM offers high sensitivity and can detect mass changes, but struggles to distinguish between adsorption molecules. Optical tweezers enable contactless manipulation of microparticles and are suitable for single-molecule studies, but require high-precision optical systems. Confocal Raman microscopy provides chemical composition information, but has relatively low spatial resolution. The recently developed dynamic frequency modulation (DFM) force spectroscopy offers high spatial resolution and is suitable for measuring local mechanical properties. It has become a key technique for investigating the structure and mechanical properties of solid-liquid interfaces. Generally speaking, the interaction between the AFM probe and molecular / ionic clusters within the interfacial double layer allows for subnanometer-scale real-space imaging of solid-liquid interface structures during electrochemical processes. However, the currently applicable in-situ electrolytic cells for atomic force microscopy all utilize the mechanical drive principle of conventional piezoelectric ceramics, or the photothermal drive method. The mechanical vibration method will drive the resonance of various components of the electrolytic cell, resulting in a large noise signal, making it difficult to obtain a clear probe vibration resonance spectrum, and greatly limiting the minimum feature size of the device characterization; the photothermal drive method uses a laser to heat the probe to localize the probe vibration, which improves the signal-to-noise ratio, but also introduces thermal disturbances and a complex optical path system. Therefore, developing an AFM in-situ electrolytic cell with localized drive capability is a core challenge to improve the interfacial force spectrum and study the molecular structure of the electrochemical solid-liquid interface. Summary of the Invention

[0003] The purpose of the present invention is to provide an atomic force microscope in-situ electrolytic cell device for measuring solid-liquid interface molecular force spectra, which is magnetically driven and suitable for atomic force microscope testing. It can realize in-situ online measurement of dynamic interface force spectra based on atomic force microscope during the electrochemical process, and observe the double-layer molecular / ion adsorption arrangement structure and interface structure evolution process at the electrode-electrolyte interface in real time in liquid electrolyte.

[0004] The technical solution adopted in the present invention is:

[0005] The invention discloses an atomic force microscope in-situ electrolytic cell device for measuring molecular force spectrum at solid-liquid interface, which comprises an in-situ electrolytic cell with a driving magnetic coil, a working electrode, a reference electrode and a counter electrode; the in-situ electrolytic cell comprises an optical glass window, a flange top cover, a Teflon substrate, a sealing ring, a metal sample support sheet, a central through-hole Teflon support sheet, a magnetic coil plate, a spring gasket and a flange base; a through hole is provided in the center of the Teflon substrate, a first sealing ring, a flange top cover and an optical glass window are fixed to the top of the Teflon substrate in order from bottom to top, and a second sealing ring, a metal sample support sheet, a central through-hole Teflon support sheet, a magnetic coil plate and a flange base are fixed to the bottom of the Teflon substrate in order from top to bottom; The electrode, reference electrode and counter electrode are distributed at different positions of the flange top cover and the flange base; the Teflon base and the flange top cover are connected by an inherent threaded connection, and the first sealing ring is sandwiched between the Teflon base and the flange top cover in a sandwich structure, thereby playing a sealing role; the spring gasket passes through the magnetic coil plate and the center through-hole Teflon support plate to connect the flange base and the metal sample support plate, supporting the metal sample support plate, and the second sealing ring is sandwiched between the Teflon base and the flange base in a sandwich structure to prevent electrolyte leakage; the working electrode is connected to the flange base, and is connected to the metal sample support plate through the spring gasket, and the metal sample support plate is connected to the conductive sample through the conductive silver paste.

[0006] Furthermore, the driving magnetic coil has different rolling numbers, and the operating frequency of the magnetic coil is adjusted by an external signal generator; the excitation magnetic field is generated by the magnetic wire to drive the magnetic probe to vibrate with small amplitude in the liquid, and the localized small amplitude vibration is used to accurately detect the molecular-level interaction force of the interface.

[0007] Furthermore, an electrolyte is injected into the Teflon matrix, and the electrolyte is an acidic solution, an alkaline solution or an organic solution.

[0008] Furthermore, the working electrode, reference electrode, and counter electrode are connected to an electrochemical workstation.

[0009] Furthermore, the flange top cover and flange bottom cover are formed of corrosion-resistant plastic or corrosion-resistant insulating metal, the inner wall of the flange top cover is provided with an annular thread, and the side of the flange top cover is provided with a through hole for the reference electrode and the counter electrode to connect to the interior of the electrolytic cell.

[0010] Furthermore, the optical glass window is made of sapphire glass, quartz glass or calcium fluoride, and the thickness of the optical glass window is adjustable.

[0011] Furthermore, the outer wall of the boss of the Teflon base is threaded and matches the inner wall thread of the flange top cover. A first sealing ring is provided between the two. The first sealing ring is compacted by screwing the two together to prevent leakage of the electrolyte.

[0012] Furthermore, the Teflon base and the flange base are connected by bolts, and the bolts are connected to the Teflon base through the threads provided on the flange base, and the second sealing ring, the metal sample support plate, the center through-hole Teflon support plate and the magnetic coil plate are sandwiched between the Teflon base and the flange base in a sandwich structure; the bolts are adjusted to compact the second sealing ring to prevent leakage of the electrolyte.

[0013] Furthermore, the sealing rings are all national standard sealing rings.

[0014] Furthermore, two through holes and a working electrode interface are provided on the side of the flange base, and the two through holes are used for connecting the magnetic coil plate in the electrolytic cell with wires.

[0015] The present invention adopts the above technical solution, embeds a magnetic coil inside the electrochemical electrolytic cell, and utilizes the AFM probe vibration mode driven by the magnetic coil to have highly localized, small-amplitude magnetic and wide-band characteristics, which can achieve high-precision measurement of the interaction force at the interface molecular level, which is of great significance for studying the arrangement structure imaging of double-layer molecules / ion clusters at the solid-liquid interface and the analysis of electrochemical processes.

[0016] The present invention has the following beneficial effects: (1) The present invention designs the electrolytic cell structure, cooperates with in-situ electrochemical atomic force microscopy scanning, and can effectively localize the driving force of the probe through the magnetic coil drive reserved inside the electrolytic cell. The interaction between the magnetic probe and the molecular / ion clusters inside the interface double layer is used to achieve sub-nanometer-scale real-space imaging of the solid-liquid interface structure in the electrochemical process, thereby improving the signal-to-noise ratio and having important significance for studying the electrochemical reaction mechanism. (2) The present invention has a simple and reasonable structural design, streamlined parts, low price, and easy operation. It can well assist in the needs of material electrochemical testing and atomic force microscopy data acquisition, and has broad application and promotion prospects. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] The present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments;

[0018] Figure 1 This is an exploded view of the structure of the electrolytic cell device in Example 1 of the present invention;

[0019] Figure 2 yes Figure 1 Frontal view of;

[0020] Figure 3 This is a diagram of an electrolytic cell device according to embodiment 1 of the present invention;

[0021] Figure 4 is a cross-sectional view of an electrolytic cell device according to embodiment 1 of the present invention;

[0022] Figure 5A bottom view of the flange cover according to the first embodiment of the present invention;

[0023] Figure 6 A top view of the Teflon substrate according to the first embodiment of the present invention;

[0024] Figure 7 Measured graphs of the resonance peaks of the magnetically driven probe in air and liquid in an embodiment of the present invention.

[0025] Wherein: 1: first connecting nut, 2: quartz glass window, 3: flange top cover, 4: reference and counter electrode interface, 5: reference electrode and counter electrode, 6: first sealing ring, 7: Teflon matrix, 8: negative electrode interface, 9: Teflon matrix thread, 10: sample to be tested, 11: second sealing ring, 12: metal sample support plate, 13: spring gasket, 14: center through hole Teflon support plate, 15: magnetic coil plate, 16: flange base, 17: magnetic coil interface, 18: working electrode interface, 19: first connecting nut, 20: working electrode, 21: internal thread of flange top cover, 22: center through hole, 23: reaction cell. Implementation Method

[0026] In order to make the purpose, technical solutions and advantages of the embodiments of the present application clearer, the technical solutions in the embodiments of the present application will be clearly and completely described below in conjunction with the drawings in the embodiments of the present application.

[0027] like Figures 1 to 7 As shown in FIG1 , the present invention discloses an atomic force microscope in-situ electrolytic cell device for measuring the molecular force spectrum of the solid-liquid interface.

[0028] like Figure 1 Figure 1 shows an atomic force microscope electrolytic cell device for measuring intermolecular interaction forces at a solid-liquid interface. The device includes a working electrode, a reference electrode, a counter electrode, and an electrolytic cell. The electrolytic cell comprises an optical glass window 2, a flange cover 3, a first sealing ring 6, a Teflon substrate 7, a second sealing ring 11, a metal sample support sheet 12, a spring washer 13, a central through-hole Teflon support sheet 14, a magnetic coil plate 15, and a flange base 16.

[0029] like Figure 2 、 3As shown, the center of the Teflon substrate 7 is provided with a through hole, and the top is fixed with a first sealing ring 6, a flange top cover 3 and an optical glass window 2 in sequence from bottom to top. The optical window glass material 2 is made of quartz glass with excellent corrosion resistance, and its thickness can be adjusted. The top of the electrolytic cell device in this embodiment can allow the atomic force microscope probe to enter the interior of the Teflon substrate 7 from the optical window 2 and contact or focus on the sample to be measured 10. The optical window 2 is placed on the flange top cover 3, and the optical window 2 and the flange top cover 3 are each provided with four through holes in the same position. The first connecting screw 1 is used to pass through the four through holes and is connected and fixed with the first connecting nut. An annular thread is provided on the inner wall of the flange top cover 3, which can be connected with the thread on the outer wall of the boss of the Teflon substrate 7. A first sealing ring 6 is provided between the flange top cover 3 and the Teflon substrate 7. The first sealing ring 6 is compacted by screwing the two together to prevent leakage of the electrolyte.

[0030] like Figure 2 、 3 As shown, the bottom of the Teflon substrate 7 comprises, from top to bottom, a second sealing ring 11, a metal sample support sheet 12, a spring washer 13, a central through-hole Teflon support sheet 14, a magnetic coil plate 15, and a flange base 16. The spring washer 13 supports the metal sample support sheet 12 and passes through the central through-hole Teflon support sheet 14 and the magnetic coil plate 15, abutting against the flange base 16. The operating frequency of the magnetic coil plate 15 is adjusted by an external signal generator to drive the magnetic probe for magnetically driven tapping mode imaging. Signals detected at the resonant frequency are amplified. The magnetic coil plate 15 can have different numbers of coils. The flange base 16 and the Teflon substrate 7 are threaded and bolted together, forming a sandwich structure between the flange base 16 and the Teflon substrate 7. The adjusting bolt squeezes the second sealing ring 11 to achieve a sealing effect and prevent leakage of the electrolyte.

[0031] like Figure 4 、 5 As shown in Figures 6 and 7, two through holes 4 are provided on the side of the flange top cover 3 for the reference electrode and the counter electrode to be connected to the inside of the electrolytic cell. Two through holes 17 and a working electrode interface 18 are provided on the side of the flange base 16. The two through holes 17 are magnetic coil interfaces for connecting the magnetic coil plate in the electrolytic cell with wires. The working electrode is connected to the flange base 16 and can be connected to the metal sample support plate 12 through the spring gasket 13. The working electrode, reference electrode and counter electrode are distributed in different positions of the flange top cover 3 and the flange base 16. The metal sample support plate 12 is connected to the sample to be tested 10 through conductive silver paste.

[0032] The material of the flange top cover 3 and the flange base 16 can be corrosion-resistant plastic such as Teflon matrix 7 polytetrafluoroethylene (PTFE) or corrosion-resistant insulating metal to extend the service life of the electrolytic cell.

[0033] In this embodiment, a method for using an atomic force microscope electrolytic cell device for measuring the intermolecular interaction force at a solid-liquid interface includes the following steps:

[0034] (1) First, bond the sample to be tested to the metal support plate and ensure that the sample to be tested and the metal support plate are conductive. Place the flange bottom at the bottom and install the magnetic coil plate, the center through-hole Teflon support plate, the spring, the metal support plate, the sealing ring and the Teflon base from bottom to top. Lead out two insulated wires from the magnetic coil. The sample to be tested is now passed upward through the window of the base so that it is located in the center of the electrolytic cell window. Ensure that the surface of the sample to be tested is flat and connect the electrolytic cell base by tightening the bolts at the bottom of the flange so that the sealing ring and spring on the metal support plate are squeezed to achieve the functions of sealing and connection respectively. At this time, use a multimeter to measure that the metal support plate and the flange bottom should be in a conductive state, that is, the working electrode can be inserted to conduct with the sample.

[0035] (2) Cut a circular lithium strip as the negative electrode and wrap it around the thread of the electrolytic cell base. Be careful to wrap it over the through hole so that the reference electrode and counter electrode connected later can contact and squeeze the lithium strip. After wrapping the lithium strip, put on the sealing ring, connect the flange top cover, screw it to the electrolytic cell base, and squeeze the sealing ring to prevent leakage. Finally, screw the quartz glass window on the top cover with bolts to prevent electrolyte leakage.

[0036] (3) After installing the electrolytic cell, insert the reference electrode and the counter electrode, and squeeze the pre-embedded lithium bar to serve as the negative electrode during the charge and discharge process. Insert the working electrode and connect it to the film to be tested, which serves as the positive electrode during the charge and discharge process. Then, inject the electrolyte into the electrolytic cell, making sure that the electrolyte level submerges the height of the lithium bar.

[0037] (4) Install the electrolytic cell on the sample stage of the atomic force microscope, connect the working electrode, reference electrode, and counter electrode to the electrochemical workstation, connect the wires from the magnetic coil to the phase-locked amplifier, scan the resonant frequency and set the dynamic lock, and quantify the amplitude / force coefficient. In situ measurement of the physical and chemical process of the surface of the sample to be tested during the electrochemical charge and discharge process. Figure 7 As shown in FIG. 1 , the measured resonance peaks of the magnetically driven probe in the embodiment of the present invention in air and liquid.

[0038] (5) After the test is completed, turn off the instrument, turn off the power, and end the test.

[0039] The present invention adopts the above technical solution, using a magnetic coil at the bottom of the electrolytic cell to excite a magnetic probe into localized, small-amplitude vibrations, thereby improving the signal-to-noise ratio of interfacial molecular force spectroscopy imaging. Embedding a magnetic coil within the electrochemical cell allows the AFM probe to vibrate in a highly localized, small-amplitude, and broadband manner, enabling high-precision measurement of interfacial molecular-level interaction forces. This is of great significance for studying the structural imaging of molecular / ion clusters in the double layer at solid-liquid interfaces and for analyzing electrochemical processes.

[0040] The present invention has the following beneficial effects: (1) The present invention designs the electrolytic cell structure, cooperates with in-situ electrochemical atomic force microscopy scanning, and can effectively localize the driving force of the probe through the magnetic coil drive reserved inside the electrolytic cell. The interaction between the magnetic probe and the molecular / ion clusters inside the interface double layer is used to achieve sub-nanometer-scale real-space imaging of the solid-liquid interface structure in the electrochemical process, thereby improving the signal-to-noise ratio and having important significance for studying the electrochemical reaction mechanism. (2) The present invention has a simple and reasonable structural design, streamlined parts, low price, and easy operation. It can well assist in the needs of material electrochemical testing and atomic force microscopy data acquisition, and has broad application and promotion prospects.

[0041] Obviously, the described embodiments are part of the embodiments of the present application, rather than all of the embodiments. In the absence of conflict, the embodiments in the present application and the features in the embodiments can be combined with each other. The components of the embodiments of the present application generally described and shown in the drawings here can be arranged and designed in various different configurations. Therefore, the detailed description of the embodiments of the present application is not intended to limit the scope of the application for protection, but merely represents the selected embodiments of the present application. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of this application.

Claims

1. An atomic force microscope in-situ electrolytic cell device for measuring molecular force spectra at solid-liquid interfaces, characterized by: The invention comprises an in-situ electrolytic cell with a driving magnetic coil, a working electrode, a reference electrode and a counter electrode; the in-situ electrolytic cell comprises an optical glass window, a flange top cover, a Teflon substrate, a sealing ring, a metal sample support sheet, a central through-hole Teflon support sheet, a magnetic coil plate, a spring gasket and a flange base; a through hole is provided in the center of the Teflon substrate, a first sealing ring, a flange top cover and an optical glass window are fixed on the top of the Teflon substrate from bottom to top, and a second sealing ring, a metal sample support sheet, a central through-hole Teflon support sheet, a magnetic coil plate and a flange base are fixed on the bottom of the Teflon substrate from top to bottom; the working electrode, the reference electrode and the counter electrode are distributed at different positions of the flange top cover and the flange base; the Teflon substrate and the flange top cover are connected by an inherent thread, the first sealing ring The sealing ring is sandwiched between the Teflon base and the flange top cover in a sandwich structure, thereby playing a sealing role; the spring gasket passes through the magnetic coil plate and the center through-hole Teflon support plate to connect the flange base and the metal sample support plate, supporting the metal sample support plate. The second sealing ring is sandwiched between the Teflon base and the flange base in a sandwich structure to prevent electrolyte leakage; the working electrode is connected to the flange base and connected to the metal sample support plate through the spring gasket, and the metal sample support plate is connected to the sample through the conductive silver paste; the driving magnetic coil has different rolling numbers, and the working frequency of the magnetic coil is adjusted by an external signal generator; the excitation magnetic field is generated by the magnetic wire to drive the magnetic probe to vibrate with small amplitude in the liquid, and the localized small amplitude vibration is used to accurately detect the molecular-level interaction force of the interface.

2. The atomic force microscope in-situ electrolytic cell device for measuring solid-liquid interface molecular force spectroscopy according to claim 1, characterized in that: An electrolyte is injected into the Teflon base, and the electrolyte is an acidic solution, an alkaline solution or an organic solution.

3. The atomic force microscope in-situ electrolytic cell device for measuring solid-liquid interface molecular force spectroscopy according to claim 1, characterized in that: The working electrode, reference electrode and counter electrode are connected to an electrochemical workstation.

4. The atomic force microscope in-situ electrolytic cell device for measuring solid-liquid interface molecular force spectroscopy according to claim 1, characterized in that: The flange top cover and flange bottom cover are formed of corrosion-resistant plastic or corrosion-resistant insulating metal. The inner wall of the flange top cover is provided with an annular thread, and the side of the flange top cover is provided with a through hole for the reference electrode and the counter electrode to connect to the inside of the electrolytic cell.

5. The atomic force microscope in-situ electrolytic cell device for measuring solid-liquid interface molecular force spectroscopy according to claim 1, characterized in that: The optical glass window is made of sapphire glass, quartz glass or calcium fluoride, and the thickness of the optical glass window is adjustable.

6. The atomic force microscope in-situ electrolytic cell device for measuring solid-liquid interface molecular force spectroscopy according to claim 1, characterized in that: The outer wall of the boss of the Teflon base is threaded and matches the inner wall thread of the flange top cover. A first sealing ring is set between the two. The first sealing ring is compacted by screwing the two together to prevent leakage of electrolyte.

7. The atomic force microscope in-situ electrolytic cell device for measuring solid-liquid interface molecular force spectroscopy according to claim 1, characterized in that: The Teflon base and the flange base are connected by bolts, and the bolts are connected to the threads provided on the Teflon base through the flange base, and the second sealing ring, the metal sample support plate, the center through-hole Teflon support plate and the magnetic coil plate are sandwiched between the Teflon base and the flange base; the bolts are adjusted to compact the second sealing ring to prevent leakage of the electrolyte.

8. The atomic force microscope in-situ electrolytic cell device for measuring solid-liquid interface molecular force spectroscopy according to claim 1, characterized in that: The sealing rings are all national standard sealing rings.

9. The atomic force microscope in-situ electrolytic cell device for measuring solid-liquid interface molecular force spectroscopy according to claim 1, characterized in that: The side surface of the flange base is provided with two through holes and a working electrode interface, and the two through holes are used for connecting the magnetic coil plate in the electrolytic cell with wires.

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