Infrared window suitable for full pH condition and electrochemical in-situ ATR-SEIRAS device

Abstract

The utility model belongs to the field of electrochemistry, and particularly relates to an infrared window applicable to a full pH condition and an electrochemical in-situ ATR-SEIRAS device, the infrared window is used in the electrochemical in-situ ATR-SEIRAS device, and the infrared window comprises an internal reflection infrared element, the internal reflection infrared element is arranged at the lower end of a sample cell of the electrochemical in-situ ATR-SEIRAS device, a barrier layer is deposited on the surface, facing the sample cell, of the internal reflection infrared element, and a metal film is plated on the barrier layer. Compared with the prior art, the ATR-SEIRAS device has the advantages that the problem that an infrared window of the ATR-SEIRAS device in the prior art is not suitable for being used under the strong alkaline condition (strong alkaline electrolyte) is solved, in-situ electrochemical infrared measurement under the full-pH condition is realized, richer interface information is provided for users, and the accuracy of the in-situ electrochemical infrared measurement under the full-pH condition is improved. Therefore, the electrochemical reaction process on the electrode can be analyzed more easily.

Description

Technical Field

[0001] The utility model belongs to the field of electrochemistry, and particularly relates to an infrared window applicable to all pH conditions and an in-situ electrochemical ATR-SEIRAS device. Background Technique

[0002] Electrocatalysis is a catalytic process that uses electrochemical methods to promote chemical reactions. In electrocatalysis, the occurrence of chemical reactions is controlled and regulated by the electrode potential, and usually, a catalyst is introduced on the electrode surface to increase the reaction rate and selectivity. These catalysts can lower the activation energy of chemical reactions, enabling the reaction to proceed at a lower potential. Electrocatalysis has a wide range of applications in many fields, including energy conversion and storage, environmental protection, chemical synthesis, and biomedicine.

[0003] Electrocatalytic reactions usually occur at the interface between the electrode surface and the electrolyte solution. Infrared spectroscopy can provide direct observation and characterization of the interfacial reaction process, revealing processes such as adsorption, desorption, transfer, and reaction kinetics at the interface, and providing important information for understanding and optimizing interfacial reactions. Among them, attenuated total reflection surface-enhanced infrared spectroscopy (ATR-SEIRAS) has been favored by many researchers because of its high surface sensitivity, small influence by the type of metal, simple surface selection rules, good reversibility of the spectral signal with potential changes, and the ability to provide molecular structure information on the electrode surface. However, the existing ATR-SEIRAS methods also have some limitations, such as difficulties in detecting in the low-frequency region (1200 - 400 cm -1 ), insensitivity to molecules with little change in dipole moment, and inapplicability under strong alkaline conditions.

[0004] Many electrocatalytic reactions need to be carried out in a strong alkaline electrolyte, such as oxygen evolution reaction, electro-oxidation reaction of organic small molecules, electro-reduction reaction of carbon monoxide, nitrate reduction, etc. In-depth research on the mechanism can help establish the structure-activity relationship of the catalyst and is necessary for guiding the development of efficient catalysts. Currently, for these reactions, since conventional infrared windows are easily corroded by alkalis, ATR-SEIRAS cannot be tested under strong alkaline conditions, so there is a lack of evidence at the molecular level of the reaction mechanism, restricting the development of efficient catalysts. Therefore, it is of great significance to develop a new type of alkali-resistant infrared optical window for strong alkaline systems. Content of the Utility Model

[0005] The purpose of the present utility model is to provide an infrared window applicable to all pH conditions and an in-situ electrochemical ATR-SEIRAS device to solve at least one of the above problems, so as to solve the problem that the infrared window of the existing ATR-SEIRAS device is not suitable for use in strong alkaline conditions (strong alkaline electrolytes). This solution realizes in-situ electrochemical infrared measurement under all pH conditions (including strong alkaline conditions), provides more abundant interfacial information for users, and thus can more easily analyze the electrochemical reaction process on the electrode.

[0006] The purpose of the present utility model is achieved through the following technical solutions:

[0007] The first aspect of the present utility model discloses an infrared window for all pH conditions, which is used in an in-situ electrochemical ATR-SEIRAS device. The infrared window includes an internal reflection infrared element, which is arranged at the lower end of the sample cell of the in-situ electrochemical ATR-SEIRAS device. A blocking layer is deposited on the surface of the internal reflection infrared element facing the sample cell, and a metal thin film is plated on the blocking layer.

[0008] Preferably, the cross-section of the surface of the internal reflection infrared element facing away from the sample cell is semi-circular, trapezoidal or V-shaped.

[0009] Preferably, the surface of the internal reflection infrared element facing away from the sample cell is processed with a serrated microstructure.

[0010] Preferably, the material of the internal reflection infrared element is one of silicon, germanium, calcium fluoride and zinc selenide.

[0011] Preferably, the material of the blocking layer is diamond or metal oxide. The metal oxide includes TiO 2 , Al 2 O 3 , ZrO 2 , HfO 2 , ITO and IZO.

[0012] More preferably, the material of the blocking layer is diamond or TiO 2 .

[0013] Preferably, the material of the metal thin film includes Au, Ag, Cu, Pt, Pd, Ni, Ru and Rh.

[0014] More preferably, the material of the metal thin film is Au.

[0015] Preferably, the thickness of the blocking layer is 20 - 200 nm, and the thickness of the metal thin film is 30 - 50 nm.

[0016] Further preferably, the thickness of the barrier layer is 25 nm, and the thickness of the metal thin film is 35 nm.

[0017] In a second aspect of the present utility model, an in-situ electrochemical ATR-SEIRAS device is disclosed, which includes a sample cell, an electrochemical control system, an infrared light source, a detector, and an infrared window as described in any one of the above;

[0018] The sample cell is used to hold an electrolyte under full pH conditions, and the electrolyte under full pH conditions is an electrolyte solution with any acidity or alkalinity, including strongly alkaline electrolytes, such as strongly alkaline electrolytes with pH = 12 - 14 and above 14;

[0019] The infrared window is arranged at the lower end of the sample cell, and the substance to be measured is placed on the surface of the infrared window facing the sample cell;

[0020] The electrochemical control system includes multiple electrodes and an electrical signal controller. The electrodes are immersed in an electrolyte with any pH value, and the electrical signal controller is electrically connected to each electrode;

[0021] The infrared light source is arranged facing the substance to be measured, and the detector is arranged on the reflection light path of the infrared light emitted by the infrared light source.

[0022] Preferably, both the upper and lower surfaces of the sample cell are provided with openings, and the infrared window is installed at the opening on the lower surface of the sample cell.

[0023] Preferably, the electrodes in the electrochemical control system form an electrochemical three-electrode system.

[0024] Preferably, the electrodes include a reference electrode and a counter electrode, and the electrical signal controller is electrically connected to the reference electrode, the counter electrode, and the metal thin film serving as the working electrode.

[0025] The working principle of the present utility model is as follows:

[0026] The infrared light emitted from the infrared light source irradiates the lower surface of the internal reflection infrared element and projects to the upper surface, and total reflection occurs on the upper surface and then enters the detector; the detector can analyze the infrared signals of the adsorbed species at the interface of the species to be measured on the internal reflection infrared element at different times.

[0027] In a strongly alkaline solution, the internal reflection infrared element is protected by the barrier layer to avoid the shedding of the metal thin film and the generation of interfering spectral peaks in the detection results. Therefore, this device can detect the infrared signals changing with the voltage of the substance to be measured at the interface of the material to be measured in an electrolyte with any pH value, including strongly alkaline conditions.

[0028] Compared with the prior art, the present utility model has the following beneficial effects:

[0029] This solution realizes the reliable measurement of electrochemical ATR-SEIRAS under the full pH condition system for the first time, filling the gap in the infrared spectroscopy research under strong alkaline conditions in the field of electrocatalysis.

[0030] The in-situ electrochemical infrared spectroscopy device with an infrared window in this solution can use the evanescent wave generated by the attenuated total reflection of infrared light on the upper surface of the infrared optical window to measure the adsorbed substances on the substance to be measured in the electrocatalytic reaction. The barrier layer resistant to electrolyte corrosion is made of infrared transparent material and does not affect the measurement. The application of this infrared window can obtain the molecular structure information of the adsorbed species on the electrode interface in the electrolyte solution under the full pH condition, expanding the applicable range of in-situ electrochemical infrared spectroscopy. Brief Description of the Drawings

[0031] Figure 1 It is a schematic structural diagram of an in-situ electrochemical ATR-SEIRAS device equipped with an infrared window for the full pH condition;

[0032] Figure 2 It is a schematic cross-sectional diagram of internal reflection infrared elements with different shapes;

[0033] In the figure: 1 - sample cell; 2 - internal reflection infrared element; 3 - barrier layer; 4 - metal thin film; 5 - electrical signal controller; 6 - reference electrode; 7 - counter electrode; 2-1 - semi-circular; 2-2 - trapezoidal; 2-3 - V-shaped; 2-4 - serrated microstructure. Detailed Description of the Preferred Embodiments

[0034] The present utility model will be described in detail below with reference to the accompanying drawings and specific embodiments.

[0035] Embodiment

[0036] An in-situ electrochemical ATR-SEIRAS device, as Figure 1 、 2 shown, includes a sample cell 1, an electrochemical control system, an infrared light source, a detector, and an infrared window;

[0037] The sample cell 1 is used to hold the electrolyte under the full pH condition (including strong alkaline electrolyte);

[0038] The infrared window is arranged at the lower end of the sample cell 1, and the substance to be measured is placed on the surface of the infrared window facing the sample cell 1;

[0039] The electrochemical control system includes multiple electrodes and an electrical signal controller 5. The electrodes are immersed in the electrolyte, and the electrical signal controller 5 is electrically connected to each electrode;

[0040] The infrared light source is arranged facing the substance to be measured, and the detector is arranged on the reflection light path of the infrared light emitted by the infrared light source.

[0041] Preferably, openings are provided on both the upper and lower surfaces of the sample cell 1, and the infrared window is installed at the opening on the lower surface of the sample cell 1.

[0042] More specifically, in this embodiment:

[0043] An in-situ electrochemical ATR-SEIRAS device, such as Figure 1 , includes a sample cell 1, an electrochemical control system, an infrared light source, a detector, and an infrared window. This in-situ electrochemical ATR-SEIRAS device is used to achieve in-situ electrochemical infrared measurement under all pH conditions.

[0044] Among them:

[0045] The sample cell 1 has openings at both the upper and lower end faces. An infrared window is installed at the opening on the lower end face. The interior contains an electrolyte. The electrode for forming the test circuit extends into the interior of the sample cell 1 through the opening on the upper end face and is immersed in the electrolyte. This electrolyte can be any electrolyte under all pH conditions, including strongly alkaline electrolytes.

[0046] The infrared window includes an internal reflection infrared element 2, which is installed at the opening on the lower end face of the sample cell 1. On the side surface of the internal reflection infrared element 2 facing the sample cell 1, a blocking layer 3 is first deposited (which can be by methods such as atomic layer deposition (ALD), physical vapor deposition (PVD), or chemical vapor deposition (CVD)) to block the corrosion of the internal reflection infrared element 2 by OH in the alkaline solution; further, a metal thin film 4 is plated (which can be by methods such as PVD or electroless plating) on the blocking layer 3. On the one hand, it is used for electron conduction and can serve as the working electrode in the electrochemical control system. On the other hand, it can amplify the infrared signal of the substance to be measured disposed thereon, thereby realizing the measurement of weak species at the interface. The side surface of the internal reflection infrared element 2 facing away from the sample cell 1 can be designed into a suitable shape. For example, its cross-section can be semi-circular 2-1, trapezoidal 2-2, or V-shaped 2-3. As - shown, when the test range needs to be expanded to 4000 - 650 cm Figure 2 , a serrated microstructure 2-4 is further processed on the side surface of the internal reflection infrared element 2 facing away from the sample cell 1. Among the above, the material of the internal reflection infrared element 2 is one of silicon, germanium, calcium fluoride, and zinc selenide; the optional materials for the blocking layer 3 are diamond or metal oxides, and the metal oxides include TiO -1 , Al 2 , Al 2 O 3 , ZrO 2 , HfO 2 , ITO, and IZO, preferably diamond or TiO 2; The optional materials of the metal film 4 include Au, Ag, Cu, Pt, Pd, Ni, Ru and Rh, preferably Au; the thickness of the barrier layer 3 is controlled at 20 to 200 nm, and the thickness of the metal film 4 is controlled at 30 to 50 nm, preferably the thickness of the barrier layer 3 is 25 nm and the thickness of the metal film 4 is 35 nm.

[0047] The electrochemical control system adopts an electrochemical three-electrode system, including an electric signal controller 5 (using an existing commercially available product, used to control the electric signal applied to the electrode), a reference electrode 6, a counter electrode 7 and a working electrode, wherein the working electrode is concurrently served by a metal film 4. Therefore, in this device, the electric signal controller 5 is electrically connected to the reference electrode 6, the counter electrode 7 and the working electrode, respectively, and the reference electrode 6 and the counter electrode 7 are respectively extended into the sample cell 1 and immersed in the electrolyte. The electric signal controller 5 can provide voltage for the working electrode, and based on the ionic conductivity of the electrolyte, a current loop is formed between the working electrode and the counter electrode 7, and the reference electrode 6 is used to control the specific voltage value applied to the working electrode.

[0048] The substance to be tested is placed on the metal film 4, and the electrical signal controller 5 can control the voltage signal of the substance to be tested; the infrared light emitted from the infrared light source irradiates the lower surface of the internal reflection infrared element 2 to reach the upper surface, and after detecting the infrared signal on the interface of the substance to be tested on the upper surface, it is totally reflected and then enters the detector; the detector can analyze the infrared signals of the adsorbed species on the interface of the substance to be tested on the infrared window at different times.

[0049] In a strong alkaline solution, the internal reflection infrared element 2 is protected by the barrier layer 3 to avoid the metal film 4 from falling off and the generation of interfering spectral peaks in the detection results. Therefore, the device can detect infrared signals on the interface of the material to be tested that change with the voltage of the material to be tested under strong alkaline conditions.

[0050] The above description of the embodiments is to facilitate the understanding and use of the utility model by those skilled in the art. It is obvious that those familiar with 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 utility model is not limited to the above embodiments, and improvements and modifications made by those skilled in the art based on the disclosure of the utility model without departing from the scope of the utility model should be within the scope of protection of the utility model.

Claims

1. An infrared window for full pH conditions, used in an electrochemical in situ ATR-SEIRAS device, the infrared window comprising an internal reflection infrared element (2), the internal reflection infrared element (2) being arranged at the lower end of a sample cell (1) of the electrochemical in situ ATR-SEIRAS device, characterized in that: A barrier layer (3) is deposited on the surface of the internal reflection infrared element (2) facing the sample pool (1), and a metal film (4) is plated on the barrier layer (3).

2. An infrared window for full pH conditions according to claim 1, characterized in that: The cross section of the surface of the internal reflection infrared element (2) facing away from the sample pool (1) is semicircular (2-1), trapezoidal (2-2) or V-shaped (2-3).

3. An infrared window for full pH conditions according to claim 1, characterized in that: The surface of the internal reflection infrared element (2) facing away from the sample pool (1) is processed with a sawtooth-shaped microstructure (2-4).

4. An infrared window for full pH conditions according to claim 1, characterized in that: The material of the barrier layer (3) is diamond or TiO2.

5. The infrared window for full pH conditions according to claim 1, characterized in that: The material of the metal film (4) is Au.

6. An infrared window for full pH conditions according to claim 1, characterized in that: The thickness of the barrier layer (3) is 20-200 nm, and the thickness of the metal film (4) is 30-50 nm.

7. An electrochemical in-situ ATR-SEIRAS device, characterized in that: It comprises a sample cell (1), an electrochemical control system, an infrared light source, a detector and an infrared window as claimed in any one of claims 1 to 6; The sample pool (1) is used to contain electrolytes under full pH conditions; The infrared window is arranged at the lower end of the sample pool (1), and the substance to be tested is placed on the surface of the infrared window facing the sample pool (1); The electrochemical control system comprises a plurality of electrodes and an electrical signal controller (5), wherein the electrodes are immersed in an electrolyte, and the electrical signal controller (5) is electrically connected to each electrode; The infrared light source is arranged toward the substance to be detected, and the detector is arranged on the reflected light path of the infrared light emitted by the infrared light source.

8. An electrochemical in-situ ATR-SEIRAS device according to claim 7, characterized in that: The upper and lower surfaces of the sample pool (1) are both provided with openings, and the infrared window is installed at the opening on the lower surface of the sample pool (1).

9. The electrochemical in-situ ATR-SEIRAS device according to claim 7, characterized in that: The electrodes in the electrochemical control system constitute an electrochemical three-electrode system.

10. An electrochemical in-situ ATR-SEIRAS device according to claim 9, characterized in that: The electrodes include a reference electrode (6) and a counter electrode (7), and the electrical signal controller (5) is electrically connected to the reference electrode (6), the counter electrode (7) and the metal film (4) serving as a working electrode.

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