Capillary tube encapsulation system

Abstract

The application provides a capillary packaging system, which comprises an end cover, a threaded sleeve, a top cover and a capillary; the inner diameter of the threaded sleeve matches the outer diameter of the capillary; the end cover is in extrusion fit with the lower part of the threaded sleeve; and the top cover is in extrusion fit with the upper part of the threaded sleeve. The capillary packaging system provided by the application can realize direct sampling in the electrolyte in the near electrode area (<100 microns) and improve the spatial resolution.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of differential electrochemical mass spectrometry, in particular to a capillary packaging system. BACKGROUND

[0002] In the field of electrochemical research, it is necessary to test the products of electrochemical reactions qualitatively and quantitatively. Currently, common product testing methods include nuclear magnetic resonance, liquid chromatography, gas chromatography, etc. The response time of these technologies is usually long, and it is difficult to characterize the substances generated and consumed near the electrode surface in real time. In order to realize the real-time monitoring of the conversion of reactants near the electrode and the generation of products, many researchers have devoted themselves to the development of differential electrochemical mass spectrometry.

[0003] Differential electrochemical mass spectrometry (DEMS) realizes sampling near the electrode through differential sampling and maintains the pressure difference between the vacuum chamber and the sampling port through a pre-vacuum system, so that the gas pressure in the vacuum chamber is maintained within the appropriate working pressure range (10e -6 ~ 10e -5 hPa) of the mass spectrometer monitor. Since electrochemical reactions are usually carried out in a certain solvent (such as water), when designing the mass spectrometry sampling system, a filter membrane with certain permeation selectivity needs to be used to reduce the permeation of the solvent (such as water) as much as possible, increase the permeation of gaseous substances (such as carbon dioxide, ethylene, etc.) as much as possible, reduce the pressure of the vacuum system, and improve the sensitivity of the system. The current sampling method of differential electrochemical mass spectrometry is mainly through a differential vacuum system connected to the gas diffusion electrode of the electrochemical cell to realize sampling from the electrode. This sampling method samples the entire electrode and cannot achieve spatial resolution, and has many limitations on the structure of the electrochemical reaction cell. Through capillary sampling, spatial resolution can be improved, and it can be flexibly used in various configurations of electrochemical cells. SUMMARY

[0004] The purpose of the present application is to provide a capillary packaging system to realize direct sampling in the electrolyte near the electrode region (<100 microns) in differential electrochemical mass spectrometry testing and improve spatial resolution.

[0005] The first aspect of the present application provides a capillary packaging system, which comprises an end cap, a threaded sleeve, a top cap, a capillary, and a sealing membrane; the inner diameter of the threaded sleeve matches the outer diameter of the capillary; the sealing membrane covers the aperture of the lower end of the capillary; the end cap is extruded and matched with the lower part of the threaded sleeve; and the top cap is extruded and matched with the upper part of the threaded sleeve.

[0006] The capillary packaging system of the present application can realize direct sampling in the electrolyte near the electrode region (<100 microns), which is crucial for accurate analysis of gas substances generated in the electrochemical reaction process, improves the accuracy and sensitivity of the test, and makes the test results more true and reliable, thereby facilitating researchers to more deeply understand the reaction mechanism.

[0007] In some embodiments of the present application, the upper part of the end cap is cylindrical, and the lower part is a circular truncated cone; the upper part and the lower part of the threaded sleeve are circular truncated cones, and the middle part is cylindrical; the top cap is cylindrical, and the upper part of the top cap has a circular truncated cone-shaped inner cavity, and the lower part has a cylindrical inner cavity.

[0008] In some embodiments of the present application, the upper part of the end cap is provided with internal threads, the middle part of the threaded sleeve is provided with external threads, and the lower part of the cylindrical inner cavity of the top cap is provided with internal threads; the external threads and the internal threads are used in cooperation.

[0009] In some embodiments of the present application, the inner diameter of the capillary is 0.1-0.5 microns.

[0010] In some embodiments of the present application, the thickness of the sealing film is 0.03-0.1 mm.

[0011] The second aspect of the present application provides a use of the capillary packaging system provided in the first aspect of the present application for differential electrochemical mass spectrometry sampling.

[0012] The present application has the following beneficial effects:

[0013] The present application provides a capillary packaging system, which can realize direct sampling in the electrolyte near the electrode region (<100 microns) in differential electrochemical mass spectrometry testing through the design of the capillary end packaging structure, improves the accuracy and sensitivity of the test, and further realizes real-time and accurate monitoring of gas products in the electrochemical reaction process, so that researchers can observe the small changes and intermediate products in the reaction process and deeply understand the reaction mechanism. In addition, using the capillary packaging system for sampling can also reduce the limitation on the structure of the electrochemical reaction cell, and broaden the application range of the test.

[0014] Of course, implementing any product or method of the present application does not necessarily require achieving all the advantages described above at the same time. BRIEF DESCRIPTION OF DRAWINGS

[0015] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the drawings needed to be used in the embodiments or prior art description will be briefly introduced below. Obviously, the drawings in the following description are only some embodiments of the present application, and other embodiments can also be obtained by those skilled in the art based on these drawings.

[0016] Fig. 1 Figure 1 is a drawing of an end cap of an embodiment of the present application;

[0017] Fig. 2 Figure 2 is a drawing of a threaded sleeve of an embodiment of the present application;

[0018] Fig. 3 Figure 3 is a drawing of a top cap of an embodiment of the present application;

[0019] Figs. 4a to 4d Figure 4 is a drawing of a capillary packaging system installation schematic of an embodiment of the present application;

[0020] Fig. 5 Figure 5 is a drawing of a DEMS testing device schematic of an embodiment of the present application;

[0021] Fig. 6a Figure 6 is a LSV curve of current vs. voltage of a CO2 reduction reaction tested using a capillary packaging system of an embodiment of the present application;

[0022] Fig. 6b Figure 7 is a curve of reactant DEMS signal vs. time of a CO2 reduction reaction tested using a capillary packaging system of an embodiment of the present application;

[0023] Fig. 6c Figure 8 is a curve of product DEMS signal vs. time of a CO2 reduction reaction tested using a capillary packaging system of an embodiment of the present application. DETAILED DESCRIPTION

[0024] The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all the embodiments of the present application. All other embodiments obtained by a person skilled in the art based on the present application belong to the scope of protection of the present application.

[0025] At present, the sampling mode of differential electrochemical mass spectrometry is mainly connected with the gas diffusion electrode of the electrochemical cell through a differential vacuum system to realize sampling from the vicinity of the electrode. This sampling mode samples the entire electrode and cannot realize spatial resolution, and has many limitations on the structure of the electrochemical reaction cell. Based on this, the present application provides a capillary packaging system to realize direct sampling in the electrolyte in the vicinity of the electrode (<100 microns) and improve the spatial resolution.

[0026] The first aspect of the present application provides a capillary packaging system, as shown in Figure 4, which comprises an end cap 1, a threaded sleeve 2, a top cap 3, a capillary 4 and a sealing film 5; the inner diameter of the threaded sleeve 2 matches the outer diameter of the capillary 4; the sealing film 5 covers the pores at the lower end of the capillary 4; the end cap 1 is extrusion-fitted with the lower part of the threaded sleeve 2; and the top cap 3 is extrusion-fitted with the upper part of the threaded sleeve 2.

[0027] In the differential electrochemical mass spectrometry test, the spatial resolution can be improved by capillary sampling, and the electrochemical cell of various configurations can be flexibly used. By coating the sealing film 5 on the aperture at the lower end of the capillary 4, the cooperation of the capillary 4 and the threaded sleeve 2, the extrusion cooperation of the top cover 3 and the end cover 1 with the threaded sleeve 2, the entire capillary packaging system has liquid tightness in the electrochemical reaction cell, realizes direct sampling in the electrolyte in the near electrode area (<100 microns), and further realizes real-time monitoring of the electrochemical reaction conversion process.

[0028] In some embodiments of the present application, as shown in Figs. 1 to 3 , the upper part of the end cover 1 is cylindrical, and the lower part is circular truncated cone; the upper part and the lower part of the threaded sleeve 2 are circular truncated cone, and the middle part is cylindrical; the top cover 3 is cylindrical, and the upper part of the top cover 3 has a circular truncated cone inner cavity, and the lower part has a cylindrical inner cavity.

[0029] In some embodiments of the present application, as shown in Figs. 1 to 3 , the upper part of the end cover 1 is provided with internal threads, the middle part of the threaded sleeve 2 is provided with external threads, and the lower part of the cylindrical inner cavity of the top cover 3 is provided with internal threads; the external threads and the internal threads are used in cooperation.

[0030] The installation schematic diagram of the capillary packaging system of an embodiment of the present application is shown in Figs. 4a to 4d , the inner diameter of the threaded sleeve 2 matches the outer diameter of the capillary 4, the lower part of the threaded sleeve 2 is flush with the capillary 4, and the sealing film collectively covers the aperture at the lower end of the capillary 4 and the lower part of the threaded sleeve 2. The top cover 3 is screwed into the threaded sleeve, the circular truncated cone inner cavity of the upper part of the top cover 3 and the upper part of the threaded sleeve 2 are extruded with each other, and the sealing of the solvent is realized. The end cover 1 is screwed into the threaded sleeve 2, the lower part of the end cover 1 and the lower part of the threaded sleeve 2 are extruded with each other, and the sealing of the solvent is realized. The external threads of the threaded sleeve 2 are tightly engaged with the internal threads of the end cover 1 and the top cover 3, so that the entry of the solvent can also be prevented. The entire packaging structure of the capillary packaging system of the present application has liquid tightness, can be directly immersed in the solvent, and realizes real-time sampling in the electrolyte.

[0031] In some embodiments of the present application, the inner diameter of the capillary is 0.1 μm to 0.5 μm. For example, the inner diameter of the capillary can be 0.1 μm, 0.2 μm, 0.3 μm, 0.4 μm, 0.5 μm, or a range composed of any two of the above values. By controlling the inner diameter of the capillary within the above range, the sampling spatial resolution can be improved, and high-precision sampling can be realized.

[0032] In some embodiments of the present application, the thickness of the sealing film is 0.03mm to 0.1mm. For example, the thickness of the sealing film is 0.03mm, 0.05mm, 0.07mm, 0.1mm or a range between any two of the above values. Controlling the thickness of the sealing film within the above range can make the capillary packaging system have higher liquid tightness.

[0033] In the present application, the material of the sealing film is not particularly limited as long as the purpose of the present application can be achieved. For example, polydimethylsiloxane (PDMS) or polytetrafluoroethylene (PTFE) can be used, and the two materials have the advantages of high toughness, good hydrophobicity and good air permeability.

[0034] In the present application, the material of the capillary, the end cap, the top cap and the threaded sleeve is not particularly limited as long as the purpose of the present application can be achieved. For example, the material of the capillary, the end cap and the top cap can be polyether ether ketone (PEEK), which has high hardness and is not easy to deform; the material of the threaded sleeve can be PTFE, which has low hardness and is easy to deform to achieve sealing.

[0035] In the present application, the outer diameter and length of the capillary are not particularly limited as long as the purpose of the present application can be achieved.

[0036] The second aspect of the present application provides a use of the capillary packaging system provided by the first aspect of the present application for differential electrochemical mass spectrometry sampling.

[0037] Examples

[0038] Hereinafter, examples and comparative examples are given to more specifically explain the embodiments of the present application. Various tests and evaluations are carried out according to the following methods. In addition, unless otherwise specified, "parts" and "%" are based on mass.

[0039] Test method and apparatus:

[0040] Linear voltammetry scan (LSV) test:

[0041] The electrochemical reaction cell is subjected to linear voltammetry scan using an electrochemical workstation, and the scan range is set to -0.5V to -2V and the scan rate is 1mV / s, to obtain a linear voltammetry scan curve.

[0042] Differential electrochemical mass spectrometry (DEMS) test:

[0043] The capillary packaging system prepared in Example 1 is installed into a DEMS test device, and an electron impact ion source (electron intensity 70eV) and a quadrupole mass spectrometer (Inficon The MPH100M detector was used, with a Faraday cup as the detector. The electron multiplier was not turned on, and the dwell time for each mass-to-charge ratio was set to 64 ms. The reactants and products of the electrochemical reaction were tested.

[0044] Example 1

[0045] <End Cap Design>

[0046] like Fig. 1 As shown, the end cap 1 is made of polyetheretherketone (PEEK). The upper part of the end cap 1 is 5 mm long, the lower part is 4.5 mm long, the upper outer diameter of the end cap 1 is 5 mm, the lower end outer diameter of the end cap 1 is 2.5 mm, the lower end inner diameter of the end cap 1 is 2 mm, and the upper internal thread of the end cap 1 is an M4 coarse thread.

[0047] <Threaded Fitting Design>

[0048] like Fig. 2 As shown, the threaded sleeve 2 is made of polytetrafluoroethylene. The upper and lower parts of the threaded sleeve 2 are 5 mm long, the middle part is 10 mm long, the inner diameter of the threaded sleeve 2 is 1.7 mm, which matches the capillary tube 4 with an outer diameter of 1 / 16 inch. The external thread in the middle of the threaded sleeve 2 is an M4 coarse thread.

[0049] <Top Cover Design>

[0050] like Fig. 3 As shown, the upper and lower parts of the top cover 3 are both 5mm in length, the outer diameter of the top cover 3 is 5mm, the top diameter of the upper inner cavity of the top cover 3 is 2mm, and the internal thread on the lower inner cavity of the top cover 3 is an M4 coarse thread.

[0051] <Installation of the capillary encapsulation system>

[0052] according to Figs. 4a to 4d The steps shown illustrate the installation of the capillary encapsulation system. The inner diameter of the threaded sleeve 2 matches the outer diameter of the capillary 4, and the lower part of the threaded sleeve 2 is flush with the capillary 4, as shown. Fig. 4a As shown. Fig. 4b As shown, the top cover 3 is screwed into the threaded sleeve 2, causing the frustum-shaped inner cavity of the top cover 3 to press against the upper part of the threaded sleeve 2. Fig. 4c As shown, a PTFE membrane with a diameter of 10 mm and a thickness of 0.05 mm is wrapped around the pore at the lower end of the capillary 4 and the lower part of the threaded sleeve 2. The end cap 1 is screwed into the threaded sleeve 2, and the PTFE membrane is compressed and fixed between the lower part of the end cap 1 and the lower part of the threaded sleeve 2. The external thread of the threaded sleeve 2 tightly engages with the internal threads of the end cap 1 and the top cap 3. The completed capillary encapsulation system is shown below. Fig. 4d As shown.

[0053] like Fig. 5As shown, the capillary packaging system of Example 1 can be used to achieve real-time detection of the products of electrochemical reactions, taking the reduction of CO2 as an example. In the figure, WE represents the working electrode (Cu-loaded gas diffusion electrode), RE represents the saturated AgCl / Ag reference electrode, and CE represents the graphite counter electrode. The capillary packaging system probe is close to the working electrode (<100 microns), and samples the near-electrode region. Linear sweep voltammetry is performed on the reaction cell, with a scan range of -2.5V to -4.0V and a scan rate of 1mV / s. The LSV curve is as shown in Fig. 6a As shown, the DEMS test data is as shown in Fig. 6b and Fig. 6c As shown, the mass-to-charge ratios 27, 28, 31, and 44 correspond to ethylene, carbon monoxide, ethanol, and carbon dioxide, respectively.

[0054] As can be seen from Example 1, the capillary packaging system designed in the present application can achieve direct sampling in the near-electrode region (<100 microns) of the electrolyte, improving the spatial resolution.

[0055] The above description is merely preferred embodiments of the present application, and is not intended to limit the present application. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application shall be included in the scope of protection of the present application.

Claims

1. A capillary encapsulation system for direct injection of samples into the electrolyte of an electrochemical reaction cell into a region smaller than 100 micrometers near the electrode using differential electrochemical mass spectrometry, comprising an end cap, a threaded sleeve, a top cap, a capillary, and a sealing membrane; the inner diameter of the threaded sleeve matches the outer diameter of the capillary; the sealing membrane covers the pores at the lower end of the capillary; the end cap is press-fitted with the lower part of the threaded sleeve; the top cap is press-fitted with the upper part of the threaded sleeve; The lower part of the threaded sleeve is flush with the capillary tube, and the sealing film together covers the pore at the lower end of the capillary tube and the lower part of the threaded sleeve. The upper part of the end cap is cylindrical and the lower part is frustum-shaped; the upper and lower parts of the threaded sleeve are frustum-shaped, and the middle part is cylindrical; the top cover is cylindrical, and the upper part of the top cover has a frustum-shaped inner cavity and the lower part has a cylindrical inner cavity. The thickness of the sealing film is 0.03mm to 0.1mm; The sealing membrane is made of polydimethylsiloxane or polytetrafluoroethylene.

2. The capillary encapsulation system according to claim 1, wherein, The upper part of the end cap is provided with an internal thread, the middle part of the threaded sleeve is provided with an external thread, and the lower cylindrical inner cavity of the top cover is provided with an internal thread; the external thread and the internal thread are used in conjunction.

3. The capillary packaging system according to claim 1, wherein, The inner diameter of the capillary is 0.1μm~0.5μm.

4. Use of the capillary encapsulation system according to any one of claims 1 to 3 for differential electrochemical mass spectrometry sample introduction.

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