In-situ infrared electrochemical cell for analysis and detection and method of use thereof

Abstract

The present invention discloses an in-situ infrared electrochemical cell for analysis and detection, which is used to be placed inside an infrared spectrometer and connected to the infrared spectrometer for use. The in-situ infrared electrochemical cell includes a cell body for containing electrolyte and a base for fixing the cell body; the cell body includes a left cell body, a right cell body, and a connection portion connecting the left cell body and the right cell body; a counter electrode is provided on the top of the cell body, and a reference electrode is provided on the top of the right cell body; the base is located directly below the right cell body, and a receiving space with an upward opening is provided inside the cell body, which can be used to partially accommodate the reaction chamber of the right cell body, and a working electrode is provided on the side of the base. Through the above-mentioned method, an in-situ infrared electrochemical cell is provided that can achieve electrolyte convection balance, low electrolyte consumption, high detection sensitivity, and simple and quick assembly and cleaning of the electrochemical cell. The in-situ infrared electrochemical cell is used for analysis and detection to achieve ultra-sensitive quantitative detection of metal ions.

Description

Technical Field

[0001] The present invention relates to the field of electrochemical analysis, and in particular to an in-situ infrared electrochemical cell for analysis and detection. Background Art

[0002] Infrared spectroscopy (FTIR) is based on the absorption of infrared radiation by a substance, which causes changes in the molecular dipole moment and thus provides information on molecular structure and composition. In situ FTIR allows real-time detection of the substance being measured and is typically available in four modes: transmission, diffuse reflectance, attenuated total reflectance (ATR), and reflection-absorption. Electrocatalytic analysis and detection systems typically involve immersed and fixed electrode surfaces. Using attenuated total reflectance-infrared spectroscopy (ATR-IR) minimizes interference from water in the electrolyte layer, facilitating the monitoring of adsorbed species on the electrode surface and enabling indirect or direct analysis and detection of the analyte. Furthermore, by analyzing the infrared spectral signal, the electrochemical reaction process and reaction control steps can be determined, thereby revealing the electrochemical reaction mechanism. In the ATR-IR mode, the incident infrared beam is positioned near the critical angle of the ATR crystal, causing the evanescent wave formed above the crystal to interact with the adsorbed molecules. Due to the surface enhancement effect of the thin metal layer on top of the reflective crystal surface, electromagnetic field resonance is generated, which in turn enhances the infrared signal and enables highly sensitive detection. In the prior art, the ATR crystal in an in-situ infrared H-type electrochemical cell is usually located at the base of the electrochemical cell. The solution cannot be stirred during the reaction, resulting in an inability to accurately detect adsorbed species on the catalyst surface.

[0003] In the prior art, patent application number CN105352917A discloses an in-situ electrochemical infrared spectroscopy-mass spectrometry detection system, which includes a three-electrode electrolytic cell, a surface-enhanced infrared reflectance spectrometer, an in-situ mass spectrometer, and an in-situ infrared transmission spectrometer. The three-electrode electrolytic cell consists of a counter electrode electrolytic cell, a working electrode electrolytic cell, a reference electrode electrolytic cell, and an ion exchange membrane. The surface-enhanced infrared reflectance spectrometer consists of an attenuated total reflection infrared emitter, a ZnSe prism, and a reflected infrared signal receiver. The in-situ mass spectrometer consists of a mass spectrometer rod, a vacuum pump, a glass capillary, and a PTFE membrane connected in sequence. The in-situ infrared transmission spectrometer consists of an electrolyte reservoir, a waste liquid reservoir, a peristaltic pump, a CaF2 capillary glass tube, an infrared transmission light emitter, and an infrared transmission light receiver. In this technical solution, a ZnSe prism is used as the ATR crystal, and its hemispherical plane is located at the bottom of the research electrode electrolytic cell. This setting is prone to the phenomenon that the solution cannot be stirred during the electrochemical reaction, resulting in the inability to accurately detect the adsorbed species on the catalyst surface.

[0004] In view of the above problems, it is urgent to rationally design new in-situ infrared electrochemical cells to solve the above problems. Summary of the Invention

[0005] The object of the present invention is to provide an in-situ infrared electrochemical cell and a method for using the cell, which can achieve electrolyte convection balance, use less electrolyte, have high detection sensitivity, and are simple and quick to assemble and clean.

[0006] In order to achieve the above object, the present invention proposes the following technical solutions:

[0007] An in-situ infrared electrochemical cell for analysis and detection, the device is used to be placed inside an infrared spectrometer and connected to the infrared spectrometer;

[0008] The in-situ infrared electrochemical cell comprises a cell body for containing electrolyte and a base for fixing the cell body;

[0009] The cell body includes a left cell body, a right cell body, and a connecting portion connecting the left cell body and the right cell body; a counter electrode is provided on the upper portion of the left cell body, and a reference electrode is provided on the upper portion of the right cell body;

[0010] The base is located directly below the right cell body. The base is provided with a receiving space opening upward for partially accommodating the reaction chamber of the right cell body. A working electrode is provided on the side of the base, and one end of the reference electrode located in the right cell body extends to one side of the working electrode.

[0011] Furthermore, a counter electrode interface for the counter electrode to pass through is provided on the top of the left cell body. The counter electrode is fixed to the top of the left cell body through the counter electrode interface and immersed in the electrolyte in the left cell body.

[0012] Furthermore, the electrode interface upper cover is provided with a first top cover and a sealing rubber gasket built into the first top cover.

[0013] Furthermore, a reference electrode interface for the reference electrode to pass through is provided on the top of the right cell body, and a second top cover and a sealing rubber gasket built into the second top cover are provided on the reference electrode interface.

[0014] Furthermore, the placement direction of the working electrode and the extension direction of the reference electrode are perpendicular to each other.

[0015] Furthermore, the working electrode is an ATR crystal, the side of the ATR crystal facing the base cavity is a plane with a thin film conductive layer on the plane, and the side away from the base cavity is a 60° prism.

[0016] Furthermore, an ion exchange membrane is provided in the connecting portion.

[0017] Furthermore, a magnet is placed at the bottom of the right pool.

[0018] Furthermore, the working electrode is an ATR crystal, and the ATR crystal is a 1.5-2 cm Si prism, Ge prism or ZnSe prism.

[0019] The present invention also provides a method for in-situ electrochemical infrared detection using the in-situ infrared electrochemical cell for analysis and detection, comprising the following steps:

[0020] S1. Equipment Connection: Connect the in-situ infrared electrochemical cell to the internal equipment of the infrared spectrometer. Next, add HClO₄ reaction solution containing trace metal ions to the electrolyte inlet and introduce carbon monoxide gas to saturate the electrolyte. Use the reference electrode holder, counter electrode holder, and working electrode holder of the electrochemical workstation inside the infrared spectrometer to connect the reference electrode, counter electrode, and working electrode, respectively.

[0021] S2. Preparation of the working electrode: A gold film is plated on the surface of the working electrode using a chemical reduction method.

[0022] S3. Quantitative detection of metal ions: The applied potential is controlled at -0.2 V vs RHE, and the metal ions are deposited on the surface of the gold-coated working electrode using a constant potential deposition method. The incident infrared light from an in-situ infrared spectrometer is totally reflected from the surface of the working electrode, thereby collecting the infrared spectral signal of the carbon monoxide probe molecules adsorbed on the deposited metal on the surface of the working electrode, achieving ultra-sensitive detection of metal ions.

[0023] The beneficial effects of the present invention are:

[0024] The present invention provides an in-situ infrared electrochemical cell that can be used for analysis and detection, and a method for using the same. The in-situ infrared electrochemical cell is placed inside an infrared spectrometer and connected to the infrared spectrometer for use, thereby combining infrared technology with electrocatalysis technology to achieve ultra-sensitive detection of metal ions. The reference electrode is placed in the inner cavity of the base through the inner cavity of the right cell body and close to the working electrode window, thereby shortening the distance between the end of the reference electrode and the working electrode, and reducing the uncompensated impedance during the test. The working electrode is arranged on the side of the base, and a magnet can be arranged at the bottom of the right cell body to promote electrolyte convection balance, reduce background interference during the test, and make the infrared signal at the working electrode interface more realistic. The above-mentioned in-situ infrared electrochemical cell is used for Pt 2+ The analysis and detection of Pt 2+ Ultra-sensitive quantitative detection with a minimum detection limit of 10 ppq. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 Schematic diagram of the structure of the in-situ infrared electrochemical cell for analysis and detection of the present invention;

[0026] Figure 2 yes Figure 1 A schematic diagram of the structure of the base;

[0027] Figure 3 The different concentrations of Pt collected in Example 1 of the present invention 2+CO adsorption infrared spectrum;

[0028] Figure 4 The Pt collected in Example 1 of the present invention 2+ Infrared spectrum of CO adsorption within the linear range;

[0029] The reference numerals are as follows:

[0030] 100. In-situ infrared electrochemical cell; 11. Left cell body; 12. Right cell body; 13. Connecting part; 20. Base; 21. Cell body interface; 22. Magnet; 23. Working electrode window; 24, 25, 27, 28 screw holes; 30. Working electrode; 111. Counter electrode; 112. Counter electrode interface; 113. First top cover; 121. Reference electrode; 122. Reference electrode interface; 123. Gas inlet; 124. Gas outlet; 125. Second top cover; 126. Third top cover; 127. Fourth top cover. DETAILED DESCRIPTION

[0031] In order to make the objectives, technical solutions and advantages of the present invention more clear, the present invention is described in detail below with reference to the accompanying drawings and specific embodiments.

[0032] It should also be noted that, in order to avoid obscuring the present invention due to unnecessary details, only structures and / or processing steps closely related to the solutions of the present invention are shown in the drawings, while other details that are not closely related to the present invention are omitted.

[0033] In addition, it should be noted that the terms "comprises", "includes" or any other variations thereof are intended to cover non-exclusive inclusion, so that a process, method, article or apparatus that includes a series of elements includes not only those elements, but also includes other elements not explicitly listed, or also includes elements inherent to such process, method, article or apparatus.

[0034] See also Figure 1 and Figure 2 As shown, the present invention provides an in-situ infrared electrochemical cell 100 for analysis and detection, which is placed inside an infrared spectrometer and connected to the infrared spectrometer to achieve the combination of infrared technology and electrocatalytic technology, and is suitable for ultra-sensitive detection of metal ions.

[0035] The in-situ infrared electrochemical cell 100 includes a cell body for holding electrolyte and a base 20 for securing the cell body. The cell body comprises a left cell body 11, a right cell body 12, and a connecting portion 13 connecting the left and right cell bodies 11 and 12. An ion exchange membrane is disposed within the connecting portion 13 to control the exchange of specific conductive ions and prevent the passage of other ions.

[0036] The upper portion of the left cell body 11 is provided with an electrode interface 112 for the passage of the counter electrode 111, a first top cover 113 covering the electrode interface 112, and a sealing rubber gasket housed within the first top cover 113. One end of the counter electrode 111 passes through a hole in the sealing rubber gasket and is immersed in the electrolyte within the left cell body 11. In this embodiment, the counter electrode 111 is a platinum wire or a graphite rod.

[0037] The upper portion of the right cell body 12 is provided with a reference electrode interface 122 for the passage of a reference electrode 121, a gas inlet 123 and a gas outlet 124 located on either side of the reference electrode interface 122, and a second top cover 125, a third top cover 126, and a fourth top cover 127, respectively covering the reference electrode interface 122, gas inlet 123, and gas outlet 124. A sealing rubber gasket is located within the second top cover 125 to secure the reference electrode 121. In this embodiment, the reference electrode 121 is a silver / silver chloride electrode or a calomel electrode.

[0038] See also Figure 2 Combined with Figure 1 As shown, the base 20 is disposed below the right cell body 12. The base 20 is provided with a cell body interface 21 for inserting the right cell body 12 into the base 20. A receiving space is provided within the base 20 for partially accommodating the reaction chamber of the right cell body 12. The receiving space is open upward. Specifically, a magnet 22 is placed at the bottom of the right cell body 12.

[0039] A working electrode window 23 and a working electrode 30 secured to the working electrode window 23 via an O-ring are provided on the side of the base 20. In this embodiment, the working electrode 30 is an ATR crystal, with the side facing the inner cavity of the base 20 being a flat surface with a thin film conductive layer, and the side facing away from the inner cavity of the base 20 being a 60° prism. It should be noted that the ATR crystal can be a 1.5-2 cm Si prism, Ge prism, or ZnSe prism. The working electrode window 23 is a circular window with an inner diameter of 1.5 cm.

[0040] With this arrangement, reference electrode 121 sequentially passes through reference electrode interface 122 and cell interface 21 at the bottom of right cell body 12, reaching the housing space of base 20. Simultaneously, working electrode 30 is positioned to the side of base 20, shortening the distance between the end of reference electrode 121 and working electrode 30 and reducing uncompensated impedance during testing. Furthermore, magneton 22 facilitates electrolyte convection balance, thereby eliminating background interference during testing and making the infrared signal at the working electrode interface more realistic, ultimately achieving efficient detection of metal ions or chemical reaction mechanisms at different potentials or currents.

[0041] In particular, screw holes 24, 25, 26, and 27 are provided on the four diagonal corners of the base 20 for connecting the in-situ infrared electrochemical cell with the internal facilities of the infrared spectrometer.

[0042] The present invention also provides an analysis and detection method using the above-mentioned in-situ infrared electrochemical cell 100, comprising the following steps:

[0043] S1. Equipment Connection: Connect the in-situ infrared electrochemical cell 100 to the internal equipment of the infrared spectrometer; then, add HClO4 reaction solution containing trace metal ions to the electrolyte inlet, and introduce carbon monoxide gas to saturate the electrolyte; use the reference electrode holder, counter electrode holder, and working electrode holder of the electrochemical workstation inside the infrared spectrometer to connect the reference electrode 121, counter electrode 111, and working electrode 30, respectively;

[0044] S2. Preparation of the working electrode: A gold film was plated on the surface of the working electrode 30 by chemical reduction;

[0045] S3. Analysis and Detection of Metal Ions: The applied potential is controlled at -0.2 V vs RHE, and the metal ions are deposited on the surface of the gold-coated working electrode 30 using a constant potential deposition method. The incident infrared light from an in-situ infrared spectrometer is totally reflected from the surface of the working electrode 30, thereby collecting the infrared spectral signal of the carbon monoxide probe molecules adsorbed on the deposited metal on the surface of the working electrode 30, thereby achieving ultra-sensitive detection of metal ions.

[0046] Example 1

[0047] The above-mentioned in-situ infrared electrochemical cell 100 is used to measure the Pt 2+ The detection range and linear range of the assay were investigated, including the following steps:

[0048] S1. Equipment connection: The in-situ infrared electrochemical cell 100 is connected to the internal equipment of the infrared spectrometer; then, a trace amount of PtCl4 is added to the electrolyte inlet. 2- The 0.1M HClO4 reaction solution was saturated with carbon monoxide gas; the reference electrode clamp, the counter electrode clamp, and the working electrode of the electrochemical workstation inside the infrared spectrometer were respectively connected to the reference electrode 121, the counter electrode 111, and the working electrode 30;

[0049] S2. Preparation of the working electrode: A gold film was plated on the surface of the working electrode 30 by chemical reduction;

[0050] S3.Pt 2+ Investigation of the detection range and linear range: The applied potential was controlled to be -0.2V vs RHE, and metal ions were deposited on the surface of the gold-coated working electrode 30 using a constant potential deposition method. The incident infrared light of the in-situ infrared spectrometer was totally reflected on the surface of the working electrode 30, thereby collecting the infrared spectrum signal of the carbon monoxide probe molecule adsorbed on the metal deposited on the surface of the working electrode 30. In this embodiment, PtCl4 2-The concentration range is 10ppq~100ppm. Figure 3 As shown, the infrared spectrum is located at 2080cm -1 The peaks are Au-CO peaks and Pt-CO peaks generated by Pt in the constant potential deposition reaction solution. When PtCl4 2- When the concentration range is 10 ppq to 100 ppm, CO is only adsorbed on the Pt surface in a linear form (Pt-CO L ), the peak is located at 1990cm -1 With the PtCl4 2- As the concentration of PtCl4 in the reaction solution increases, the peak area increases gradually, but the increase is not large. 2- When the concentration increases to 50ppm~100ppm, CO is in the form of bridge (Pt-CO B ) and linear forms are adsorbed on the Pt surface. 2- With the increase of concentration, the peak area changes significantly and the peak position shifts. Figure 4 As shown, when PtCl4 2- When the concentration range of CO is 10ppq~5ppt, the adsorption peak area of ​​CO on the Pt surface is 2+ The concentration of Pt is linearly related to the linear relationship, which can be used as a standard curve for the detection of metal ions within the concentration range by using the above-mentioned in-situ infrared electrochemical cell. 2+ When detecting CO, the standard curve can be applied to further determine the adsorption peak area of ​​Pt on the surface of CO. 2+ Ultrasensitive quantitative detection.

[0051] Principle of analysis and detection: A three-electrode system is used, and a potential / current is applied to the working electrode 30. Metal ions are deposited on the surface of the working electrode 30 using a constant potential / constant current deposition method. Carbon monoxide molecules are used as probes. At the same time, infrared spectroscopy is used to in situ collect infrared spectra at different potentials / currents. By analyzing the adsorption of carbon monoxide molecules on the deposited metal surface in the infrared spectra, ultra-sensitive quantitative detection of metal ions is achieved.

[0052] In summary, the present invention provides an in-situ infrared electrochemical cell 100 for analytical detection and a method for using the same. The device is intended to be placed inside an infrared spectrometer and connected to the infrared spectrometer for use. The in-situ infrared electrochemical cell 100 includes a cell body for containing electrolyte and a base 20 for securing the cell body. The cell body includes a left cell body 11, a right cell body 12, and a connecting portion 13 connecting the left and right cell bodies. A counter electrode 111 is provided at the top of the left cell body 11, and a reference electrode 121 is provided at the top of the right cell body. The base 20 is located directly below the right cell body 12. The base 20 includes a receiving space with an upwardly facing reaction chamber that can partially accommodate the right cell body 12. A working electrode 30 is provided on the side of the base 20. Through the above-described method, an in-situ infrared electrochemical cell is provided that achieves electrolyte convection balance, reduces electrolyte usage, achieves high detection sensitivity, and allows for simple and quick assembly and cleaning of the electrochemical cell. Using this in-situ infrared electrochemical cell 100 for analytical detection can achieve ultrasensitive quantitative detection of metal ions. Using a three-electrode system, a potential / current is applied to the working electrode 30 to deposit Pt 2+ Deposited on the surface of the working electrode, with carbon monoxide molecules as probes, infrared spectroscopy is used to collect infrared spectra at different potentials / currents in situ, and the adsorption of carbon monoxide molecules on the deposited Pt surface is analyzed by infrared spectra. 2+ Ultra-sensitive quantitative detection with a minimum detection limit of 10 ppq.

[0053] The above descriptions are merely embodiments of the present invention and are not intended to limit the patent scope of the present invention. Any equivalent structure or equivalent process transformation made using the contents of the present invention's description and drawings, or directly or indirectly applied in other related technical fields, are also included in the patent protection scope of the present invention.

Claims

1. An in-situ infrared electrochemical cell for analysis and detection, characterized in that: It is used to be placed inside an infrared spectrometer and connected to the infrared spectrometer for use; the in-situ infrared electrochemical cell is used for ultra-sensitive quantitative detection of metal ions; The in-situ infrared electrochemical cell comprises a cell body for containing electrolyte and a base (20) for fixing the cell body; The cell body comprises a left cell body (11), a right cell body (12), and a connecting portion (13) connecting the left cell body (11) and the right cell body (12); a counter electrode (111) is provided on the upper portion of the left cell body (11), and a reference electrode (121) is provided on the upper portion of the right cell body (12); a magnet (22) is placed on the bottom of the right cell body (12); The base (20) is located directly below the right cell body (12), and the base (20) is provided with a receiving space with an upward opening for partially receiving the reaction chamber of the right cell body (12). A working electrode (30) is provided on a side of the base (20), and one end of the reference electrode (121) located in the right cell body (12) extends to one side of the working electrode (30); The working electrode (30) is an ATR crystal, the side of the ATR crystal facing the inner cavity of the base (20) is a plane with a thin film conductive layer on the plane, and the side away from the inner cavity of the base (20) is a 60° prism; the ATR crystal is a 1.5-2 cm Si prism, Ge prism or ZnSe prism.

2. The in-situ infrared electrochemical cell for analysis and detection according to claim 1, characterized in that: The top of the left cell body (11) is provided with an electrode interface (112) for the electrode (111) to pass through. The electrode (111) is fixed to the top of the left cell body (11) through the electrode interface (112) and immersed in the electrolyte in the left cell body (11).

3. The in-situ infrared electrochemical cell for analysis and detection according to claim 2, characterized in that: The upper cover of the electrode interface (112) is provided with a first top cover (113) and a sealing rubber gasket built into the first top cover (113).

4. The in-situ infrared electrochemical cell for analysis and detection according to claim 1, characterized in that: The top of the right cell body (12) is provided with a reference electrode interface (122) for the reference electrode (121) to pass through, and the reference electrode interface (122) is covered with a second top cover (125) and a sealing rubber gasket built into the second top cover (125).

5. The in-situ infrared electrochemical cell for analysis and detection according to claim 1, characterized in that: The placement direction of the working electrode (30) and the extension direction of the reference electrode (121) are perpendicular to each other.

6. The in-situ infrared electrochemical cell for analysis and detection according to claim 1, characterized in that: An ion exchange membrane is provided in the connecting portion (13).

7. A method for in-situ electrochemical infrared detection using the in-situ infrared electrochemical cell for analysis and detection according to any one of claims 1 to 6, characterized in that: The steps include: S1. Equipment connection: connecting the in-situ infrared electrochemical cell to the internal equipment of the infrared spectrometer; then, adding HClO4 reaction solution containing trace metal ions to the electrolyte inlet, and introducing carbon monoxide gas for saturation; using the reference electrode clamp, counter electrode clamp, and working electrode of the electrochemical workstation inside the infrared spectrometer to connect the reference electrode (121), the counter electrode (111), and the working electrode (30), respectively; S2. Preparation of the working electrode: a gold film is plated on the surface of the working electrode (30) by a chemical reduction method; S3. Quantitative detection of metal ions: The applied potential is controlled to be -0.2 V vs RHE, and metal ions are deposited on the surface of the working electrode (30) coated with the gold film by a constant potential deposition method. The incident infrared light of an in-situ infrared spectrometer is totally reflected on the surface of the working electrode, thereby collecting infrared spectral signals of carbon monoxide probe molecules adsorbed on the deposited metal on the surface of the working electrode (30), thereby achieving ultra-sensitive detection of metal ions; The method for in-situ electrochemical infrared detection by the in-situ infrared electrochemical cell for analysis and detection detects Pt 2+ The minimum detection limit was 10 ppq.

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