In-situ electrochemical infrared spectrum-Raman spectrum combined device

Abstract

The invention relates to a detection device, in particular to an in-situ electrochemical infrared spectrum-Raman spectrum combined device which comprises a sample cell, an infrared component, a Raman component and an electro-catalysis component, openings are respectively formed in the top and the bottom of the sample cell; the infrared assembly comprises an infrared optical window, an infrared light source and an infrared detector; the infrared optical window is assembled at the bottom opening of the sample cell, and the surface of the infrared optical window is plated with a conductive metal coating; a substance to be detected is arranged on the conductive metal coating; the Raman assembly comprises a Raman optical fiber probe and a Raman optical window; the Raman optical window is assembled at a top opening of the sample cell; the electro-catalysis assembly comprises a reference electrode, a counter electrode and a power supply mechanism; the sample cell is filled with electrolyte, and the reference electrode and the counter electrode are inserted into the electrolyte. Compared with the prior art, in-situ infrared and in-situ Raman synchronous real-time detection of electrode interface adsorption species (namely substances to be detected) is realized.

Description

Technical Field

[0001] The invention relates to a detection device, in particular to an in-situ electrochemical infrared spectroscopy-Raman spectroscopy combined device. Background Art

[0002] Electrochemistry mainly studies the conversion between electrical energy and chemical energy and between electrical energy and matter. It has wide applications in many fields, such as energy, materials, metal corrosion and protection, life sciences, electroanalytical sensors, microelectronics, etc. The electrode / solution interface is the core place that controls and influences the entire electrochemical reaction, involving the transfer process of ions and electrons. Therefore, it is crucial to explore the structure and change process of the electrode / solution interface for electrochemical reactions. However, the physical and chemical processes at the electrode / solution interface overlap and influence each other, making the study of its structure and process extremely challenging. Traditional electrochemical methods can only provide macroscopic electrical signal parameters, but cannot provide microscopic interface reaction information.

[0003] Infrared spectroscopy is a widely used molecular detection technology that can provide detailed information on the chemical structure of molecules. In situ electrochemical infrared spectroscopy has taken the study of electrochemical interfaces to a new level, from the macro to the micro, from statistical average to the molecular level. Among them, electrochemical surface enhanced infrared spectroscopy (ATR-SEIRAS) has been favored by researchers due to its high surface sensitivity, little influence of metal types, simple surface selection, good reversibility of spectral signals with potential changes, and the ability to provide molecular structure information on the electrode surface, such as the material component detection device and method disclosed in patent CN202210418006.5. However, the existing ATR-SEIRAS method also has some limitations, such as the low-frequency region (1200-400cm -1 ) detection difficulties and insensitivity to molecules with little change in dipole moment.

[0004] Raman spectroscopy is a light scattering technique. The incident laser interacts with the sample, causing the wavelength of the scattered light to change. The frequency and intensity of the Raman scattered light are used to characterize the vibration and rotation energy level characteristics of the sample molecules. It is sensitive to changes in the polarizability of the molecules and has a detection range of 50-4000cm -1 In situ electrochemical surface enhanced Raman is more sensitive to adsorbed molecules with large changes in polarizability at the electrode interface, and has more advantages in detection in the low-frequency region than infrared, but it is difficult to detect molecules with relatively small changes in polarizability.

[0005] At present, there are only separate in-situ electrochemical infrared spectroscopy or in-situ electrochemical Raman spectroscopy technologies for the detection of species to be tested on the electrode interface, and the two technologies cannot be combined. According to the detection principle, Raman spectroscopy and infrared spectroscopy are complementary. The combination of in-situ electrochemical surface-enhanced infrared and electrochemical surface-enhanced Raman technology can simultaneously obtain more comprehensive molecular structure information of adsorbed species on the electrode interface within a wide frequency range, achieving the effect of 1+1 greater than 2. In addition, the combination of in-situ electrochemical infrared spectroscopy and Raman spectroscopy does not require sample transfer, and can achieve the simultaneous acquisition of infrared and Raman signals of the same sample under the same test conditions, so as to obtain more accurate in-situ reaction information.

[0006] Patent CN201710441766.7 discloses a sealed electrolytic cell for in-situ detection of Raman and infrared spectroscopy and a method for using the same. However, in this solution, only Raman spectroscopy detection or infrared spectroscopy detection can be performed separately, or infrared spectroscopy detection can be performed in the gap between Raman spectroscopy detection. Therefore, it is impossible to realize real-time and continuous joint detection, which easily leads to the loss of detection information.

[0007] Therefore, it is of great significance to develop a combined device for in situ electrochemical infrared spectroscopy and Raman spectroscopy. Summary of the invention

[0008] The purpose of the present invention is to provide an in-situ electrochemical infrared spectroscopy-Raman spectroscopy combined device in order to solve at least one of the above problems, so as to address the deficiency of the prior art in the lack of a device combining in-situ infrared spectroscopy and Raman spectroscopy for electrocatalytic reactions. The present invention realizes the synchronous real-time detection of electrode interface adsorbed species (i.e., the substance to be tested) by in-situ infrared and in-situ Raman, providing users with richer interface information, thereby making it easier to analyze the electrochemical reaction process on the electrode.

[0009] The purpose of the present invention is achieved through the following technical solutions:

[0010] An in-situ electrochemical infrared spectroscopy-Raman spectroscopy combined device comprises a sample cell, an infrared component, a Raman component and an electrocatalytic component;

[0011] The sample pool has openings at the top and bottom respectively;

[0012] The infrared component comprises an infrared optical window, an infrared light source and an infrared detector; the infrared optical window is mounted at the bottom opening of the sample cell, and the upper surface of the infrared optical window is plated with a conductive metal coating; the substance to be tested is arranged on the conductive metal coating; the infrared light source is arranged toward the substance to be tested through the infrared optical window, and the infrared detector is arranged on the reflected light path of the infrared light emitted by the infrared light source;

[0013] The Raman component includes a Raman optical fiber probe and a Raman optical window; the Raman optical window is installed at the top opening of the sample pool, and the Raman optical fiber probe is arranged toward the substance to be tested through the Raman optical window;

[0014] The electrocatalytic component includes a reference electrode, a counter electrode and a power supply mechanism; the sample cell is filled with electrolyte, the reference electrode and the counter electrode are inserted into the electrolyte, and the power supply mechanism is electrically connected to the reference electrode, the counter electrode and the conductive metal coating respectively.

[0015] The infrared light emitted from the infrared light source irradiates the lower surface of the infrared optical window and reaches the upper surface, where it is totally reflected and then enters the infrared detector; the infrared detector can then analyze the infrared signals of the adsorbed species on the infrared optical window at different times. The Raman light emitted by the Raman fiber probe passes through the Raman optical window and the electrolyte to reach the adsorbed species placed on the infrared optical window, where it is scattered on the adsorbed species; the Raman fiber probe also receives the Raman scattered light and transmits it to the Raman detector, thereby obtaining the Raman signal. Thus, the infrared light and the Raman light detect the signal to be measured on the same species to be measured.

[0016] The conductive metal coating is used for electron conduction (so the infrared optical window with metal film can be used as the working electrode in the electrochemical three-electrode system). On the other hand, it can amplify the infrared signal of the adsorbed species on it to measure the weak species on the interface. The electrolyte has ionic conductivity, so a current loop is formed between the working electrode (conductive metal coating) and the counter electrode, and the reference electrode is used to control the specific voltage value applied to the working electrode.

[0017] Therefore, the combined device can simultaneously detect infrared signals and Raman signals on the interface of the material to be tested while changing the voltage of the material to be tested.

[0018] Preferably, the sample pool is further provided with an electrolyte inlet and an electrolyte outlet, respectively. The electrolyte inlet and the electrolyte outlet are symmetrically arranged with respect to the sample pool to update the electrolyte near the working electrode.

[0019] Preferably, the reference electrode is inserted into the electrolyte from the electrolyte inlet side, the counter electrode is inserted into the electrolyte from the electrolyte outlet side, and the infrared optical window and the Raman optical window are located between the reference electrode and the counter electrode.

[0020] Preferably, the distance between the Raman optical window and the infrared optical window is 0.1-5 mm.

[0021] Preferably, the distance between the Raman optical fiber probe and the substance to be measured is 5-20 mm.

[0022] Preferably, the Raman component further comprises a three-dimensional adjuster, the Raman optical fiber probe is arranged at the end of the three-dimensional adjuster, and the movement accuracy of the three-dimensional adjuster is 1 micron.

[0023] Preferably, the Raman optical window has a thickness of 0.2-2 mm.

[0024] Preferably, the infrared optical window and the sample cell are sealed by a first sealing member, and further preferably, the first sealing member is a fluororubber sealing ring to prevent leakage of electrolyte in the sample cell.

[0025] Preferably, the reference electrode and the sample cell are sealed by a second seal; the counter electrode and the sample cell are sealed by a second seal. Further preferably, the second seal is an O-ring.

[0026] Preferably, the cross-sectional shape of the infrared optical window is semicircular, trapezoidal or V-shaped.

[0027] The working principle of the present invention is:

[0028] The in-situ electrochemical infrared spectroscopy and Raman spectroscopy combined device uses the evanescent wave generated by the attenuated total reflection of infrared light on the surface of the infrared optical window to measure the adsorbed substances on the substance to be tested in the electrocatalytic reaction. At the same time, Raman light can measure the adsorbed substances on the substance to be tested in the electrocatalytic reaction through the Raman scattering signal generated by the Raman light focused on the substance to be tested. According to the detection principle, Raman spectroscopy and infrared spectroscopy are complementary and do not affect each other. The combination of in-situ electrochemical surface enhanced infrared and electrochemical surface enhanced Raman technology can synchronously obtain more comprehensive molecular structure information of adsorbed species on the electrode interface within a wide frequency range.

[0029] Compared with the prior art, the present invention has the following beneficial effects:

[0030] For the first time, the combination of electrochemistry, infrared spectroscopy and Raman spectroscopy has been realized, filling the gap in the combination of infrared spectroscopy and Raman spectroscopy in the field of electrocatalysis. The combination of in-situ electrochemical surface-enhanced infrared and electrochemical surface-enhanced Raman technology can simultaneously obtain more comprehensive molecular structure information of adsorbed species on the electrode interface within a wide frequency range, achieving the effect of 1+1 greater than 2. In addition, the combination of in-situ electrochemical infrared spectroscopy and Raman spectroscopy does not require sample transfer, and can achieve the simultaneous acquisition of infrared and Raman signals of the same sample under the same test conditions, so as to obtain more accurate in-situ reaction information and provide richer interface information, so that the electrochemical reaction process on the electrode can be more easily analyzed. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1It is a schematic diagram of the structure of the in-situ electrochemical infrared spectroscopy-Raman spectroscopy combined device;

[0032] Figure 2 It is a schematic diagram of the structural cross section of the sample cell in the in-situ electrochemical infrared spectroscopy-Raman spectroscopy combined device;

[0033] Figure 3 It is a schematic diagram of the structure of the Raman component in the in-situ electrochemical infrared spectroscopy-Raman spectroscopy combined device;

[0034] In the figure: 101-sample cell; 102-infrared optical window; 103-infrared light source; 104-infrared detector; 105-electrocatalytic component; 1051-working electrode terminal; 1052-reference electrode terminal; 1053-counter electrode terminal; 106-reference electrode; 107-counter electrode; 108-Raman component; 1081-Raman fiber optic probe; 1082-three-dimensional regulator; 109-Raman optical window; 1011-first sealing member; 1012-electrolyte inlet; 1013-sample cell pressure plate; 1014-second sealing member; 1015-electrolyte outlet; 1021-conductive metal coating; 1022-substance to be tested; 301-fixed bottom plate; 302-X-axis adjustment mechanism; 303-Y-axis adjustment mechanism; 304-Z-axis adjustment mechanism; 305-probe connecting rod. DETAILED DESCRIPTION

[0035] The present invention is described in detail below with reference to the accompanying drawings and specific embodiments.

[0036] Example

[0037] An in-situ electrochemical infrared spectroscopy-Raman spectroscopy combined device, such as Figure 1-3 As shown, it includes a sample cell 101, an infrared component, a Raman component 108 and an electrocatalytic component 105;

[0038] The sample pool 101 has openings at the top and bottom respectively;

[0039] The infrared component includes an infrared optical window 102, an infrared light source 103 and an infrared detector 104; the infrared optical window 102 is assembled at the bottom opening of the sample pool 101, and the upper surface of the infrared optical window 102 is plated with a conductive metal coating 1021; the substance to be tested 1022 is arranged on the conductive metal coating 1021; the infrared light source 103 is arranged through the infrared optical window 102 toward the substance to be tested 1022, and the infrared detector 104 is arranged on the reflected light path of the infrared light emitted by the infrared light source 103;

[0040] The Raman component 108 includes a Raman fiber probe 1081 and a Raman optical window 109; the Raman optical window 109 is mounted at the top opening of the sample pool 101, and the Raman fiber probe 1081 is disposed toward the substance to be tested 1022 through the Raman optical window 109;

[0041] The electrocatalytic component 105 includes a reference electrode 106, a counter electrode 107 and a power supply mechanism; the sample cell 101 is filled with an electrolyte, the reference electrode 106 and the counter electrode 107 are inserted into the electrolyte, and the power supply mechanism is electrically connected to the reference electrode 106, the counter electrode 107 and the conductive metal coating 1021 respectively.

[0042] More specifically, in this embodiment:

[0043] like Figure 1 As shown, the sample pool 101 is used to contain electrolyte, and the upper and lower surfaces of the sample pool 101 are both provided with openings, the infrared optical window 102 is installed at the opening of the lower surface of the sample pool 101, and the Raman optical window 109 is installed at the opening of the upper surface of the sample pool 101. The infrared optical window 102 has two surfaces, and its upper surface (the surface facing the electrolyte) is plated with a conductive metal coating 1021, which can be used for electron conduction (as a working electrode) on the one hand, and can amplify the infrared signal of the adsorbed species (the substance to be measured 1022) on it on the other hand, so as to achieve the measurement of weak species on the interface; the lower surface of the infrared optical window 102 can be designed into a variety of shapes as needed, such as a semicircular cross-section (semi-cylinder, hemisphere), a trapezoid (truncated cone), a V-shaped (cone), etc. The infrared light emitted from the infrared light source 103 irradiates the lower surface of the infrared optical window 102, penetrates the infrared optical window 102 and reaches its upper surface, and is totally reflected on the upper surface, and then enters the infrared detector 104. The infrared detector 104 can analyze the infrared signals of the adsorbed species placed on the infrared optical window 102 at different times. The Raman light emitted by the Raman fiber probe 1081 passes through the Raman optical window 109 and the electrolyte to reach the substance to be tested 1022 placed on the infrared optical window 102, and the Raman light is scattered on the substance to be tested 1022; at the same time, the Raman fiber probe 1081 also receives the Raman scattered light and transmits the data to the Raman detector (not shown in the figure), thereby obtaining the Raman signal. The Raman fiber probe 1081 and the aforementioned Raman detector are both components of the Raman spectrometer, and the Raman spectrometer can use existing commercially available products. In the in-situ electrochemical infrared and Raman combined reaction cell in the present application, infrared light and Raman light detect the signal to be tested on the same species to be tested.

[0044] The combined device also includes a three-electrode electrochemical control part, as an electrocatalytic component 105: composed of a reference electrode 106, a counter electrode 107, a working electrode (i.e., a conductive metal coating 1021), and a power supply mechanism, which is electrically connected to the reference electrode 106, the counter electrode 107, and the working electrode through the reference electrode terminal 1052, the counter electrode terminal 1053, and the working electrode terminal 1051, respectively, and can provide voltage. The reference electrode 106 and the counter electrode 107 are also inserted into the electrolyte, and the electrolyte has ionic conductivity, so a current loop is formed between the working electrode and the counter electrode 107, and the reference electrode 106 is used to control the specific voltage value applied to the working electrode. The substance to be tested 1022 is placed on the upper surface of the conductive metal coating 1021, the power supply mechanism can control the voltage signal of the substance to be tested 1022, the infrared light can detect the infrared signal on the interface of the substance to be tested 1022, and the Raman light can detect the Raman signal on the interface of the substance to be tested 1022. Therefore, the combined device in this scheme can simultaneously detect the infrared signal and the Raman signal on the interface of the material to be tested while changing the voltage of the substance to be tested 1022.

[0045] The specific structure of the sample pool 101 in this embodiment is as follows Figure 2The sample cell 101 is a symmetrical structure as a whole, with openings for inserting the reference electrode 106 and the counter electrode 107 provided on the left and right sides respectively, and the infrared optical window 102 and the Raman optical window 109 are located between the reference electrode 106 and the counter electrode 107 . More specifically, a sample cell pressing plate 1013 is installed by screws at the opening on the left side of the sample cell 101 where the reference electrode 106 is inserted. The reference electrode 106 passes through the sample cell pressing plate 1013 and then extends obliquely into the sample cell 101 and into the electrolyte. A seal is formed between the reference electrode 106 and the sample cell 101 through a second seal 1014 (O-type seal ring); a sample cell pressing plate 1013 is also installed by screws at the opening on the right side of the sample cell 101 where the counter electrode 107 is inserted. The counter electrode 107 passes through the sample cell pressing plate 1013 and then extends obliquely into the sample cell 101 and into the electrolyte. A seal is also formed between the counter electrode 107 and the sample cell 101 through a second seal 1014 (O-type seal ring). In addition, the infrared optical window 102 forms a seal with the sample cell 101 through a first seal 1011 (fluororubber seal ring) to prevent leakage of the electrolyte in the sample cell 101. The sample cell 101 is also provided with an electrolyte inlet 1012 and an electrolyte outlet 1015, which are symmetrically arranged on both sides of the sample cell 101 and connected to an external pressure device for updating the electrolyte near the working electrode; in this embodiment, the electrolyte inlet 1012 is arranged on the side of the channel where the reference electrode 106 is inserted into the sample cell 101, and the electrolyte outlet 1015 is arranged on the side of the channel where the counter electrode 107 is inserted into the sample cell 101. The Raman optical window 109 is glued to the sample cell 101, and the thickness is controlled to be 0.2-2mm, and the distance between the lower surface of the Raman optical window 109 and the infrared optical window 102 is further controlled to be 0.1-5mm.

[0046] The Raman light emitted from the Raman fiber probe 1081 has a focused spot with a size of about 1 micron. The focused spot needs to be irradiated on the substance to be tested 1022 to obtain a relatively good Raman signal. Therefore, the distance from the spot to the bottom of the Raman fiber needs to be controlled to be 5-20 mm. Therefore, in this combined device, the Raman fiber probe 1081 is further used in conjunction with the three-dimensional regulator 1082 to form a Raman component 108. Figure 3As shown. The Raman fiber probe 1081 is connected to the output end (end) of the three-dimensional adjuster 1082 through the probe connecting rod 305. The three-dimensional adjuster 1082 is further composed of an X-axis adjustment mechanism 302, a Y-axis adjustment mechanism 303 and a Z-axis adjustment mechanism 304. The mobile adjustment accuracy is controlled at 1 micron, and the three-dimensional adjuster 1082 can control the Raman fiber probe 1081 to adjust on the X, Y, and Z axes. The three-dimensional adjuster 1082 can use devices in the prior art, such as a three-axis mechanical arm, a three-axis slide, etc. In order to further improve the alignment accuracy of the Raman fiber probe 1081, the three-dimensional adjuster 1082 and the sample pool 101 are installed together on a fixed base plate 301, thereby ensuring that the approximate orientation of the Raman fiber probe 1081 is accurate, and accurate detection can be achieved after fine-tuning by the three-dimensional adjuster 1082.

[0047] The in-situ electrochemical infrared spectroscopy and Raman spectroscopy combined device in the present scheme can use the evanescent wave generated by the attenuated total reflection of infrared light on the surface of the infrared optical window 102 to measure the adsorbed substances on the substance to be tested 1022 in the electrocatalytic reaction. At the same time, Raman light can measure the adsorbed substances on the substance to be tested 1022 in the electrocatalytic reaction by the Raman scattering signal generated by the Raman light focused on the substance to be tested 1022. According to the detection principle, Raman spectroscopy and infrared spectroscopy are complementary and do not affect each other. The combination of in-situ electrochemical surface enhanced infrared and electrochemical surface enhanced Raman technology can synchronously obtain more comprehensive molecular structure information of adsorbed species on the electrode interface within a wide frequency range.

[0048] The above description of the embodiments is to facilitate the understanding and use of the invention by those skilled in the art. It is obvious that those skilled in the art can easily make various modifications to these embodiments and apply the general principles described herein to other embodiments without creative work. Therefore, the present invention is not limited to the above embodiments, and improvements and modifications made by those skilled in the art based on the disclosure of the present invention without departing from the scope of the present invention should be within the scope of protection of the present invention.

Claims

1. An in-situ electrochemical infrared spectroscopy-Raman spectroscopy combined device, It is characterized in that It includes a sample pool (101), an infrared component, a Raman component (108) and an electrocatalytic component (105); The sample pool (101) has openings at the top and bottom respectively; The infrared component comprises an infrared optical window (102), an infrared light source (103) and an infrared detector (104); the infrared optical window (102) is mounted at the bottom opening of the sample pool (101), and the upper surface of the infrared optical window (102) is plated with a conductive metal coating (1021); the substance to be tested (1022) is arranged on the conductive metal coating (1021); the infrared light source (103) is arranged through the infrared optical window (102) toward the substance to be tested (1022), and the infrared detector (104) is arranged on the reflected light path of the infrared light emitted by the infrared light source (103); The Raman component (108) comprises a Raman optical fiber probe (1081) and a Raman optical window (109); the Raman optical window (109) is mounted at the top opening of the sample pool (101), and the Raman optical fiber probe (1081) is arranged toward the substance to be tested (1022) through the Raman optical window (109); The electrocatalytic component (105) comprises a reference electrode (106), a counter electrode (107) and a power supply mechanism; the sample cell (101) is filled with an electrolyte, the reference electrode (106) and the counter electrode (107) are inserted into the electrolyte, and the power supply mechanism is electrically connected to the reference electrode (106), the counter electrode (107) and the conductive metal coating (1021) respectively.

2. The in-situ electrochemical infrared spectroscopy-Raman spectroscopy combined device according to claim 1, It is characterized in that The sample pool (101) is also provided with an electrolyte inlet (1012) and an electrolyte outlet (1015), respectively. The electrolyte inlet (1012) and the electrolyte outlet (1015) are arranged symmetrically with respect to the sample pool (101).

3. The in-situ electrochemical infrared spectroscopy-Raman spectroscopy combined device according to claim 2, It is characterized in that The reference electrode (106) is inserted into the electrolyte from the side of the electrolyte inlet (1012), and the counter electrode (107) is inserted into the electrolyte from the side of the electrolyte outlet (1015). The infrared optical window (102) and the Raman optical window (109) are located between the reference electrode (106) and the counter electrode (107).

4. The in-situ electrochemical infrared spectroscopy-Raman spectroscopy combined device according to claim 1, It is characterized in that The distance between the Raman optical window (109) and the infrared optical window (102) is 0.1-5 mm.

5. The in-situ electrochemical infrared spectroscopy-Raman spectroscopy combined device according to claim 1, It is characterized in that The distance between the Raman optical fiber probe (1081) and the substance to be tested (1022) is 5-20 mm.

6. The in-situ electrochemical infrared spectroscopy-Raman spectroscopy combined device according to claim 5, It is characterized in that The Raman component (108) further includes a three-dimensional regulator (1082), and the Raman optical fiber probe (1081) is arranged at the end of the three-dimensional regulator (1082).

7. The in-situ electrochemical infrared spectroscopy-Raman spectroscopy combined device according to claim 1, It is characterized in that The thickness of the Raman optical window (109) is 0.2-2 mm.

8. The in-situ electrochemical infrared spectroscopy-Raman spectroscopy combined device according to claim 1, It is characterized in that The infrared optical window (102) and the sample pool (101) are sealed by a first sealing member (1011).

9. The in-situ electrochemical infrared spectroscopy-Raman spectroscopy combined device according to claim 1, It is characterized in that The reference electrode (106) and the sample cell (101) are sealed via a second sealing member (1014); the counter electrode (107) and the sample cell (101) are sealed via a second sealing member (1014).

10. The in-situ electrochemical infrared spectroscopy-Raman spectroscopy combined device according to claim 1, It is characterized in that The cross-sectional shape of the infrared optical window (102) is semicircular, trapezoidal or V-shaped.

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