Atomic force microscope in-situ electrolytic tank device for measuring solid-liquid interface molecular force spectrum

Abstract

The invention discloses an atomic force microscope in-situ electrolytic tank device for measuring a solid-liquid interface molecular force spectrum, which structurally comprises a working electrode, a reference electrode, a counter electrode and an electrolytic tank, an optical glass window, a flange top cover, a Teflon base body, a sealing ring, a metal sample supporting sheet, a central through hole Teflon supporting sheet, a magnetic coil plate, a spring gasket and a flange base are sequentially arranged on the cell body from top to bottom; an opening is formed in the center of the Teflon base body, a flange top cover and an optical glass window are sequentially fixed to the top of the Teflon base body from bottom to top, and a sealing ring, a metal sample supporting piece, a center through hole Teflon supporting piece, a magnetic coil plate and a flange base are arranged at the bottom of the Teflon base body from top to bottom. An external signal source drives the magnetic coil, and solid-liquid interface structure sub-nano-scale real space imaging in the electrochemical process is achieved through the interaction between the magnetic probe and molecule / ion clusters in the interface double electrode layer. The device can assist in 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 a molecular force spectrum at a solid-liquid interface. Background Art

[0002] Solid-liquid interface molecular force spectroscopy testing technologies include atomic force microscopy (AFM), surface force instrument (SFA), quartz crystal microbalance (QCM), optical tweezers and confocal Raman microscopy. Each method has its own advantages and limitations. SFA can accurately measure the force between two surfaces and is suitable for liquid media, but is limited by the surface parallelism and transparency requirements; QCM has high sensitivity and can detect mass changes, but it is difficult to distinguish between adsorption of different molecules; optical tweezers can manipulate particles without contact and are suitable for single molecule research, but require a high-precision optical system; confocal Raman microscopy can provide chemical composition information, but the spatial resolution is relatively low; the dynamic frequency modulation AFM force spectroscopy developed in recent years has high spatial resolution and is suitable for the measurement of local mechanical properties. It has become one of the important technical means to explore the solid-liquid interface structure and mechanical information of materials. Generally speaking, the interaction between the AFM probe and the molecular / ion clusters inside the interface double layer can achieve sub-nanometer real-space imaging of the solid-liquid interface structure in the electrochemical process. However, the currently applicable in-situ electrolytic cells for atomic force microscopes all use 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, which greatly limits the minimum feature size of the device characterization; the photothermal drive method uses laser heating to localize the probe vibration, which improves the signal-to-noise ratio, but also introduces thermal disturbances and complex optical path systems. 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 spectrum, which is magnetically driven and suitable for atomic force microscope testing; it can realize in-situ online measurement of dynamic interface force spectrum based on atomic force microscope during the electrochemical process, and observe the double-layer molecular / ion adsorption arrangement structure and interface structure evolution process on the electrode-electrolyte interface in real time in liquid electrolyte.

[0004] The technical solution adopted by the present invention is: 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 on the top of the Teflon substrate in sequence 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 in sequence 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 substrate and the flange top cover are connected by an inherent threaded connection, and the first sealing ring is sandwiched between the Teflon substrate 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 central through-hole Teflon support sheet to connect the flange base and the metal sample support sheet, and plays a supporting role for the metal sample support sheet. The second sealing ring is sandwiched between the Teflon substrate 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 sheet through the spring gasket, and the metal sample support sheet is connected to the conductive sample through the conductive silver paste.

[0005] Furthermore, 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 a small amplitude in the liquid, and the localized small amplitude vibration is used to accurately detect the molecular-level interaction force of the interface.

[0006] Furthermore, an electrolyte is injected into the Teflon matrix, and the electrolyte is an acidic solution, an alkaline solution or an organic solution.

[0007] Furthermore, the working electrode, reference electrode and counter electrode are connected to an electrochemical workstation.

[0008] 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 inside of the electrolytic cell.

[0009] 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.

[0010] Furthermore, the outer wall of the boss of the Teflon substrate is threaded and matches the inner wall thread of the flange top cover. A first sealing ring is arranged between the two. The first sealing ring is compacted by screwing the two together to prevent leakage of the electrolyte.

[0011] Furthermore, 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 in a sandwich structure; the bolts are adjusted to compact the second sealing ring to prevent leakage of the electrolyte.

[0012] Furthermore, the sealing rings are all national standard sealing rings.

[0013] 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.

[0014] The present invention adopts the above technical scheme, 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-frequency domain characteristics, which can achieve high-precision measurement of the interaction force at the interface molecular level, which is of great significance for studying the imaging of the arrangement structure of double-layer molecules / ion clusters at the solid-liquid interface and the analysis of electrochemical processes.

[0015] The present invention has the following beneficial effects: (1) The present invention designs the structure of the electrolytic cell, cooperates with the in-situ electrochemical atomic force microscope 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 realize the sub-nanometer real-space imaging of the solid-liquid interface structure in the electrochemical process, improve the signal-to-noise ratio, and is important for studying the mechanism of electrochemical reactions. (2) The present invention has a simple and reasonable structural design, streamlined parts, low price, and easy operation. It can well assist the needs of material electrochemical testing and atomic force microscope data acquisition, and has broad application and promotion prospects. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] The present invention is further described in detail below with reference to the accompanying drawings and specific embodiments; Figure 1 This is a structural exploded view of the electrolytic cell device in Embodiment 1 of the present invention; Figure 2 yes Figure 1 Front view of; Figure 3 This is a diagram of an electrolytic cell device according to Embodiment 1 of the present invention; Figure 4 is a cross-sectional view of an electrolytic cell device according to Embodiment 1 of the present invention; Figure 5 A bottom view of the flange top cover according to the first embodiment of the present invention; Figure 6 A top view of a Teflon substrate according to Embodiment 1 of the present invention; Figure 7 It is a measured diagram of the resonance peak of the magnetically driven probe in the embodiment of the present invention in air and liquid.

[0017] 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

[0018] 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.

[0019] like Figures 1 to 7 As shown in one, the present invention discloses an atomic force microscope in-situ electrolytic cell device for measuring the molecular force spectrum of a solid-liquid interface. like Figure 1 As shown, an atomic force microscope electrolytic cell device for measuring the interaction force between molecules at the solid-liquid interface includes a working electrode, a reference electrode, a counter electrode, and an electrolytic cell. The electrolytic cell includes an optical glass window 2, a flange top cover 3, a first sealing ring 6, a Teflon substrate 7, a second sealing ring 11, a metal sample support sheet 12, a spring gasket 13, a central through-hole Teflon support sheet 14, a magnetic coil plate 15, and a flange base 16.

[0020] like Figure 2 , 3 As 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 allows 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 tested 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 of 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, and the first sealing ring 6 is compacted by screwing and fitting the two to prevent leakage of the electrolyte.

[0021] like Figure 2 , 3 As shown, the bottom of the Teflon substrate 7 is respectively composed of the second sealing ring 11, the metal sample support sheet 12, the spring gasket 13, the central through hole Teflon support sheet 14, the magnetic coil plate 15 and the flange base 16 from top to bottom. The spring gasket 13 supports the metal sample support sheet 12, passes through the central through hole Teflon support sheet 14 and the magnetic coil plate 15, and abuts against the flange base 16. The working frequency of the magnetic coil plate 15 is adjusted by an external signal generator, so as to drive the magnetic probe to perform magnetic drive tapping mode imaging. The signal detected at the resonance frequency will be amplified. The magnetic coil plate 15 can be selected with different numbers of coils. The flange base 16 and the Teflon substrate 7 are provided with threads, and the flange base 16 and the Teflon substrate 7 are connected by bolts, so that the second sealing ring 11, the metal sample support sheet 12, the central through hole Teflon support sheet 14 and the magnetic coil plate 15 are sandwiched 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.

[0022] 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 sheet 12 through the spring gasket 13. The working electrode, the reference electrode and the counter electrode are distributed in different positions of the flange top cover 3 and the flange base 16. The metal sample support sheet 12 is connected to the sample to be tested 10 through conductive silver paste.

[0023] 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, so as to extend the service life of the electrolytic cell.

[0024] In this embodiment, a method for using an atomic force microscope electrolytic cell device for measuring the interaction force between molecules at a solid-liquid interface includes the following steps: (1) First, bond the sample to be tested to the metal support plate and make sure 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 substrate from bottom to top. Lead out two insulated wires from the magnetic coil. The sample to be tested now passes upward through the window of the substrate 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 tighten the bolts at the bottom of the flange to connect it to the electrolytic cell substrate, 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.

[0025] (2) Cut a ring-shaped lithium strip as the negative electrode and wrap it around the thread of the electrolytic cell substrate. Note that the winding position should cover the through hole so that the reference electrode and counter electrode connected later can contact and squeeze the lithium strip. After winding the lithium strip, put on the sealing ring, connect the flange top cover, screw it to the electrolytic cell substrate, and squeeze the sealing ring to prevent leakage. Finally, screw the quartz glass window on the top cover with bolts to prevent electrolyte leakage.

[0026] (3) After installing the electrolytic cell, insert the reference electrode and the counter electrode to squeeze the pre-embedded lithium bar as the negative electrode during the charge and discharge process. Insert the working electrode and connect it to the film to be tested 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.

[0027] (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 to quantify the amplitude / force coefficient. In-situ measurement of the physical and chemical processes of the surface of the sample under test during the electrochemical charge and discharge process. Figure 7 As shown, the measured graphs of the resonance peaks of the magnetically driven probe in the embodiment of the present invention in the air and in the liquid.

[0028] (5) After the test is completed, turn off the instrument, turn off the power, and end the test.

[0029] The present invention adopts the above technical scheme, and excites the magnetic probe to perform localized small-amplitude vibration through the magnetic coil at the bottom of the electrolytic cell to improve the imaging signal-to-noise ratio of the interface molecular force spectrum. The magnetic coil is embedded in the electrochemical electrolytic cell, and the AFM probe vibration mode driven by the magnetic coil has 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 imaging of the arrangement structure of double-layer molecules / ion clusters at the solid-liquid interface and the analysis of electrochemical processes.

[0030] The present invention has the following beneficial effects: (1) The present invention designs the structure of the electrolytic cell, cooperates with the in-situ electrochemical atomic force microscope 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 realize the sub-nanometer real-space imaging of the solid-liquid interface structure in the electrochemical process, improve the signal-to-noise ratio, and is important for studying the mechanism of electrochemical reactions. (2) The present invention has a simple and reasonable structural design, streamlined parts, low price, and easy operation. It can well assist the needs of material electrochemical testing and atomic force microscope data acquisition, and has broad application and promotion prospects.

[0031] 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 claimed 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 of the art without making creative work are within the scope of protection of the present application.

Claims

1. An atomic force microscope in-situ electrolytic cell device for measuring the molecular force spectrum of a solid-liquid interface, characterized in that: 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 in sequence 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 in sequence from top to bottom; the working electrode, the reference electrode and the counter electrode are respectively The flange top cover and the flange base are arranged at different positions; the Teflon substrate and the flange top cover are connected by an inherent threaded connection, and the first sealing ring is sandwiched between the Teflon substrate 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 central through-hole Teflon support sheet to connect the flange base and the metal sample support sheet, thereby supporting the metal sample support sheet, and the second sealing ring is sandwiched between the Teflon substrate and the flange base in a sandwich structure to prevent leakage of the electrolyte; the working electrode is connected to the flange base, and is connected to the metal sample support sheet through the spring gasket, and the metal sample support sheet is connected to the conductive sample through the conductive silver paste.

2. The atomic force microscope in-situ electrolytic cell device for measuring solid-liquid interface molecular force spectrum according to claim 1, characterized in that: 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.

3. The atomic force microscope in-situ electrolytic cell device for measuring solid-liquid interface molecular force spectrum 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.

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

5. The atomic force microscope in-situ electrolytic cell device for measuring solid-liquid interface molecular force spectrum 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.

6. The atomic force microscope in-situ electrolytic cell device for measuring solid-liquid interface molecular force spectrum 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.

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

8. The atomic force microscope in-situ electrolytic cell device for measuring solid-liquid interface molecular force spectrum 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 central 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.

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

10. The atomic force microscope in-situ electrolytic cell device for measuring solid-liquid interface molecular force spectrum 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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