Longitudinal spatial resolution in-situ infrared electrolytic tank device for electro-catalysis test

Abstract

The invention belongs to the technical field of electrochemical catalysis and characterization, and particularly relates to a longitudinal spatial resolution in-situ infrared electrolytic tank device for an electro-catalysis test, which is used for monitoring the longitudinal substance change of a catalyst layer in an electro-catalysis reaction in real time. Through high-precision longitudinal adjustment, the material distribution dynamic state in the catalyst and the longitudinal depth of the electrolyte in the electro-catalytic reaction is monitored in real time; the structural design of the infrared cell is optimized, and the compatibility with a synchrotron radiation light source and an electrochemical workstation is improved. And longitudinal layered detection: integrating a plurality of infrared probes or movable optical windows at different depths of the flow cell to realize signal acquisition along the flow direction. And dynamic signal analysis: establishing a real-time model of longitudinal substance distribution in combination with fluid mechanics simulation and spectral data. High pressure / high flow velocity is compatible; an optical window material and a cell body structure are optimized, and the stability of an infrared signal under a complex working condition is ensured.

Description

Technical Field

[0001] The present invention belongs to the technical field of electrocatalytic and characterization, and particularly relates to a longitudinal spatially resolved in-situ infrared electrolytic cell device for electrocatalytic testing, which is used to monitor the longitudinal material changes in the catalyst layer during the electrocatalytic reaction in real time. Background Art

[0002] In the study of the electrocatalytic CO2 reduction reaction, the dynamic changes of substances on the catalyst surface, such as the adsorption / desorption of reaction intermediates, the distribution of electrolyte components, etc., are crucial for understanding the reaction mechanism. Traditional in-situ infrared techniques, such as ATR-FTIR and DRIFTS, have been widely used to study the surface adsorbed intermediates and catalyst structure changes in the CO2 reduction reaction, but they can only capture the signals near the catalyst-electrolyte interface and cannot penetrate the inside of the flow cell. Some studies have achieved in-situ infrared detection under flowing conditions by customizing the reaction cell, but it is still limited to signal acquisition in the surface or thin layer region and cannot dynamically monitor the longitudinal material distribution. The flow cell improves the CO2 mass transfer efficiency through forced convection, but the reactant concentration, intermediate distribution, and product generation will form gradients along the flow direction (longitudinal). Existing technologies cannot resolve this spatial heterogeneity in real time, resulting in the understanding of the reaction mechanism remaining at the macroscopic or surface level.

[0003] The following technical problems mainly exist in the prior art:

[0004] Insufficient longitudinal resolution: Existing in-situ infrared cells can only detect the signals on the catalyst surface or in the thin layer region and cannot distinguish the intermediate distributions at different depths (longitudinal) in the flow cell. The detection depth of ATR-FTIR is usually at the micron level, only reflecting the information at the electrode-electrolyte interface. Most in-situ spectroscopic techniques rely on ensemble-averaged signals and are difficult to capture local or dynamic spatial differences.

[0005] Limitations in the design of the flow cell: The optical window design of traditional flow cells is not optimized for longitudinal detection, resulting in the infrared light path being unable to penetrate different regions of the flow cell. The electrolyte flow in the liquid-phase flow cell will interfere with the stability of the infrared signal, and high-pressure or high-flow conditions may damage the optical measurement.

[0006] Monitoring blind spots in dynamic processes: The longitudinal material changes (such as reactant consumption, intermediate accumulation, product diffusion) are closely related to the distribution of catalyst active sites, but existing technologies cannot real-time correlate the data in the spatial and time dimensions. Summary of the Invention

[0007] To overcome the deficiencies of the above-mentioned prior art, the present invention provides an in-situ infrared electrolytic cell with zero pole distance and high sealing performance, which, in combination with a micron-level stepping device, realizes real-time and high-resolution monitoring of the longitudinal material distribution in the catalyst layer. Through high-precision longitudinal adjustment, the present invention can monitor in real time the dynamic material distribution inside the catalyst and in the longitudinal depth of the electrolyte during the electrocatalytic reaction; by optimizing the structural design of the infrared cell, the compatibility with synchrotron radiation light sources and electrochemical workstations is improved. Longitudinal layer-by-layer detection: Multiple infrared probes or movable optical windows are integrated at different depths of the flow cell to collect signals along the flow direction. Dynamic signal analysis: Combining hydrodynamic simulation and spectral data, a real-time model of longitudinal material distribution is established. Compatible with high pressure / high flow rate: Optimizing the optical window material and cell body structure to ensure the stability of infrared signals under complex working conditions.

[0008] The object of the present invention can be achieved through the following technical solutions:

[0009] The present invention provides a longitudinal space-resolved in-situ infrared electrolytic cell device for electrocatalytic testing, which includes an electrolytic cell main body, a micron-level stepping system, an optical system, an electrochemical system, a gas-liquid path system, a control platform, a spectral analysis module, a mass spectrometer, and a fluid simulation module.

[0010] Furthermore, the electrolytic cell main body of the present invention includes a PTFE cell body, the PTFE cell body includes an anode tank and a cathode tank, an anode insulating gasket, an anode perforated electrode plate, a membrane electrode, a cathode perforated electrode plate, and a cathode insulating gasket are sequentially arranged between the anode tank and the cathode tank, and a ZnSe window is plated on the inner wall of the cathode tank, which has both high light transmittance (infrared band transmittance > 90%) and anti-electrolyte corrosion ability, and the anode tank and the cathode tank are connected by fixing screws and fixing nuts. The schematic diagram of the electrolytic cell main body of the present invention is as Figure 1 shown, the side view of the electrolytic cell main body of the present invention is as Figure 2 shown, the disassembly diagram of the electrolytic cell main body of the present invention is as Figure 3 shown, and the internal schematic diagram of the electrolytic cell main body combined with the optical system of the present invention is as Figure 4 shown.

[0011] Furthermore, the micron-level stepping system is composed of a two-dimensional stepping motor and a high-precision displacement sensor. The resolution of the high-precision displacement sensor is 1μm, and the longitudinal adjustment range of the two-dimensional stepping motor is 0 - 20mm, with a stepping speed of 1 - 100μm / s; the electrolytic cell main body is fixed on the two-dimensional platform of the two-dimensional stepping motor, and the two-dimensional stepping motor drives the electrolytic cell main body to move longitudinally at the micron level in a direction perpendicular to the membrane electrode. The high-precision displacement sensor transmits displacement data to the electrochemical system, and through the linkage of the electrochemical workstation and the stepping motor, real-time synchronization of potential control and longitudinal position adjustment is achieved, and the electrochemical workstation transmits the displacement data to the control platform.

[0012] Further, the optical system consists of an infrared light source and a detector. The infrared light source is a synchrotron radiation light source or a Fourier transform infrared spectrometer light source. The infrared light source vertically irradiates the ZnSe window. The detector collects infrared signals of the longitudinal depth in a reflection mode, and the spectral data detected by the detector is transmitted to the control platform.

[0013] Further, the electrochemical system consists of an electrochemical workstation and a platinum counter electrode / reference electrode. The platinum counter electrode is connected to the membrane electrode. The electrochemical workstation controls the reaction potential through a three-electrode system, records the current-voltage curve in real time, and transmits the voltage-current data to the control platform.

[0014] Further, the gas-liquid path system consists of a CO2 mass flow controller and an electrolyte circulation pump. CO2 gas is input from the cathode cell inlet, and the electrolyte is input from the anode cell inlet. The product gas is analyzed for mass spectrometry data in real time by the mass spectrometer and transmitted to the control platform.

[0015] Further, the control platform synchronizes displacement data with voltage and current signals, integrates infrared spectral data, mass spectrometry data, and voltage-current data, and triggers the two-dimensional stepping motor to move; the spectral analysis module processes the original infrared signals, imports the time-position marked spectral data from the control platform, and outputs the spatial concentration gradient map of the longitudinal substance, that is, the longitudinal substance distribution heat map; the fluid simulation module simulates the electrolyte flow and mass transfer process through the data of the control platform and the spectral analysis module, optimizes the cell structure, and predicts the influence of the mass transfer boundary layer on the signal.

[0016] Further, the side of the cathode cell adopts a wedge-shaped extension method, an observation port is opened on the cathode cell bracket, and the outside of the observation port is sealed by a ZnSe window; the anode cell adopts a corresponding wedge-shaped extension but retains the side wall to meet the mass transfer on the corresponding cathode reaction side.

[0017] Furthermore, the bevel angle of the wedge-shaped extension is 15°, reducing the optical path scattering loss, and optimizing the light flux distribution through COMSOL simulation.

[0018] Further, the anode perforated electrode plate and the cathode perforated electrode plate are copper-based porous plates. The membrane electrode is a detachable carrier coated with a catalyst layer to be measured on the surface. The thickness of the catalyst layer to be measured is 1 - 10 μm, supporting rapid replacement and repeated use.

[0019] Further, the material of the ZnSe window is ZnSe material with silicon nitride deposited on the surface, improving the corrosion resistance to the electrolyte (such as KHCO3).

[0020] Further, the preparation method of the ZnSe material with silicon nitride (Si3N4) deposited on its surface includes the following steps:

[0021] The ZnSe substrate is successively ultrasonically cleaned with acetone, ethanol, and deionized water, and then placed in a vacuum chamber, where an Ar / N2 mixed gas is introduced to deposit a silicon nitride (Si3N4) anti-corrosion coating (thickness ≈ 200 nm), and finally annealing treatment is carried out.

[0022] Further, the volume ratio of Ar to N2 in the mixed gas is 4:1, the sputtering power during the deposition process is 200 W, and the deposition time is 30 min.

[0023] Further, the annealing treatment temperature is 300 °C, and the annealing treatment time is 2 h.

[0024] During the working process of the in-situ infrared electrolytic cell of the present invention, CO2 and the electrolyte are respectively input from the cathode and the anode, a reduction reaction occurs in the catalyst layer, and the product is output through the gas path. The stepping motor drives the electrolytic cell to move point by point, and the infrared spectrometer synchronously collects the signals of the catalyst layer at different depths to analyze the longitudinal distributions of CO2, intermediate products (such as *COOH, *CO), and pH value. The infrared signal is linked with the electrochemical workstation in real time to correlate the current density with the change of the substance distribution. The schematic diagram of the present invention for analyzing the essential reasons for the catalytic reaction activity and the change of intermediate products in different regions is as Figure 5 shown.

[0025] The beneficial effects that can be produced by this application are as follows:

[0026] Compared with the conventional in-situ test cell, the present invention adopts a mode of opening a window on the side based on a zero-gap electrolytic cell, which can maintain the sufficient supply of reactants and the circuit path to support a high reaction rate. The side of the cathode cell extends in a wedge shape, an observation port is opened on the bracket, and the outside is sealed with an infrared window material. The anode cell adopts a corresponding wedge-shaped extension but retains a certain thickness of the side wall to try to meet the mass transfer on the corresponding cathode reaction side. Based on this design, the side of the electrode faces the infrared detection window, and the tomographic information from the gas diffusion electrode to the ion-selective permeable membrane can be observed through the window. The reaction products are received downstream using electrochemical differential mass spectrometry. Compared with the conventional nuclear magnetic resonance, this method can quickly distinguish the changes in the product type and selectivity at different potentials within a response scale of ten seconds by controlling the reduction potential of the sample. During the test process, the position of the infrared detection optical path remains unchanged. By fixing the in-situ cell system on a two-dimensional cloud platform driven by a stepping motor, the spatial position adjustment ability at the micron level can be achieved by using the stepping motor platform, and the maximum adjustable spatial range is on the centimeter scale. It is very convenient to control the spatial periodic observation from dozens to hundreds of microns. Description of the Drawings

[0027] Figure 1 Schematic diagram of the electrolytic cell body of the present invention.

[0028] Figure 2 Side view of the electrolytic cell body of the present invention.

[0029] Figure 3 Exploded view of the electrolytic cell body of the present invention.

[0030] Figure 4 Internal schematic diagram of the electrolytic cell body of the present invention combined with an optical system.

[0031] Figure 5 Schematic diagram for analyzing the essential reasons for the changes in catalytic reaction activity and intermediate products in different regions of the present invention.

[0032] Figure 6 Graph for testing the C2 product selectivity and energy conversion efficiency of the overall electrolysis system using a zero-gap electrolytic cell.

[0033] Figure 7 Infrared spectrum diagram of the CO2 reduction intermediate products of the Cu catalyst at different potentials obtained.

[0034] Figure 8 Infrared spectrum diagram of the CO2 reduction intermediate products of the AgCu alloy catalyst at different potentials obtained.

[0035] Figure 9 Product distribution diagram of the Ag / CuO catalyst at different depths obtained. Detailed implementation manners

[0036] Next, the technical solutions in the embodiments of the present application will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present application. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present application.

[0037] The experimental methods in the following embodiments are all conventional methods unless otherwise specified, and the test materials used in the following embodiments are all commercially available through conventional channels unless otherwise specified.

[0038] Example 1

[0039] A longitudinal space-resolved in-situ infrared electrolytic cell device for electrocatalytic testing, comprising an electrolytic cell body, a micrometer-level stepping system, an optical system, an electrochemical system, a gas-liquid path system, a control platform, a spectral analysis module, a mass spectrometer, and a fluid simulation module.

[0040] The electrolytic cell body includes a PTFE cell body with dimensions of 80×50×10 mm 3 (length × width × height). A longitudinal channel with a diameter of 5 mm is arranged inside the cell body. The PTFE cell body includes an anode tank and a cathode tank. An anode insulating gasket (fluororubber), an anode perforated electrode plate, a membrane electrode, a cathode perforated electrode plate, and a cathode insulating gasket (fluororubber) are sequentially arranged between the anode tank and the cathode tank. The channel width of the cathode tank is 2 mm, the grid width is 1 mm, and the total effective area is 5 cm × 5 cm. The side of the cathode tank adopts a wedge-shaped extension, and the bevel angle of the wedge-shaped extension is 15°, reducing the loss of light path scattering and optimizing the light flux distribution through COMSOL simulation; a 1 cm * 0.5 cm observation port is opened on the cathode tank bracket, and the outside of the observation port is sealed by a ZnSe window with a thickness of 2 mm, which has both high light transmittance (light transmittance range 400 - 4000 cm -1 , infrared band transmittance > 90%) and anti-electrolyte corrosion ability; the anode tank adopts a corresponding wedge-shaped extension but retains a 2 mm thick side wall to meet the mass transfer on the corresponding cathode reaction side; the anode perforated electrode plate and the cathode perforated electrode plate are copper-based porous plates with a thickness of 1 mm and a porosity of 30%; the membrane electrode is a detachable carrier (20×20 mm 2 of Nafion 212) coated with a catalyst layer to be measured on the surface. In this embodiment, the thickness of the catalyst layer to be measured is 10 μm, which supports rapid replacement and reuse. The anode tank and the cathode tank are connected by fixing screws and fixing nuts.

[0041] The material of the ZnSe window is ZnSe material deposited with silicon nitride on the surface, improving the corrosion resistance to electrolytes (such as KHCO3). The preparation method of the ZnSe material deposited with silicon nitride (Si3N4) on the surface includes the following steps:

[0042] The ZnSe substrate is ultrasonically cleaned with acetone, ethanol, and deionized water in sequence, then placed in a vacuum chamber and Si3N4 is deposited by introducing an Ar / N2 mixed gas, and finally annealing treatment is carried out. The volume ratio of Ar to N2 in the mixed gas is 4:1. The sputtering power during the deposition process is 200 W, the deposition time is 30 min, and the thickness of the deposited silicon nitride is 200 nm. The annealing treatment temperature is 300 °C, and the annealing treatment time is 2 h.

[0043] The micron-scale stepping system consists of a Prior Scientific H101F two-dimensional stepping motor and a high-precision displacement sensor. The resolution of the high-precision displacement sensor is 1 μm. The longitudinal adjustment range of the two-dimensional stepping motor is 0 - 20 mm, and the stepping speed is adjustable from 1 - 100 μm / s. The electrolytic cell body is fixed on the two-dimensional platform of the two-dimensional stepping motor. The two-dimensional stepping motor drives the electrolytic cell body to move longitudinally at the micron scale in a direction perpendicular to the membrane electrode. The high-precision displacement sensor transmits displacement data to the electrochemical system. Through the linkage between the CHI 760E electrochemical workstation and the stepping motor, real-time synchronization of potential control and longitudinal position adjustment is achieved, and the electrochemical workstation transmits the displacement data to the LabVIEW control platform.

[0044] The optical system consists of an infrared light source and an MCT detector. The infrared light source is a synchrotron radiation light source. The infrared light source irradiates the ZnSe window vertically. The detector collects infrared signals of the longitudinal depth in the reflection mode. The spectral data detected by the detector is transmitted to the control platform.

[0045] The electrochemical system consists of an electrochemical workstation and a platinum counter electrode / reference electrode. The platinum counter electrode is connected to the membrane electrode. The electrochemical workstation controls the reaction potential through a three-electrode system, records the current-voltage curve in real time, and transmits the voltage-current data to the control platform.

[0046] The gas-liquid path system consists of a CO2 mass flow controller and an electrolyte circulation pump (0.5 mL / min). CO2 gas is input from the cathode cell inlet, and the electrolyte is input from the anode cell inlet. The product gas is analyzed for mass spectrometry data in real time by an HPR-20QIC mass spectrometer and transmitted to the control platform.

[0047] The control platform synchronizes the displacement data and voltage-current signals, integrates the infrared spectral data, mass spectrometry data, and voltage-current data, and triggers the movement of the two-dimensional stepping motor. The spectral analysis module OMNIC processes the original infrared signals, imports the time-position marked spectral data from the control platform, and outputs a spatial concentration gradient map of the longitudinal substance, i.e., a heat map of the longitudinal substance distribution. The fluid simulation module simulates the electrolyte flow and mass transfer process through the data of the control platform and the spectral analysis module, optimizes the cell structure, and predicts the influence of the mass transfer boundary layer on the signal.

[0048] The in-situ electrolytic cell assembly and testing process of this embodiment is as follows:

[0049] Hot press the catalyst onto the surface of a detachable carrier sheet (i.e., the ion exchange membrane Nafion 212); assemble the anode cell, anode perforated electrode plate, membrane electrode, cathode perforated electrode plate, cathode cell, ZnSe window, and anode insulating gasket and cathode insulating gasket in sequence; fix it on the stepping motor platform and connect the electrochemical workstation and gas path system. Introduce a humidified CO2 flow rate (50 sccm) and anode electrolyte (0.5 M KHCO3); apply a constant potential (0.8 V vs. RHE), start the stepping motor to scan longitudinally along the catalyst layer (step size 10 μm), synchronously record infrared spectra, current density, and mass spectrometry data, analyze the correlation between the substance distribution and reaction activity, and the obtained C2 product selectivity and energy conversion efficiency diagram of the overall electrolysis system tested with a zero-gap electrolytic cell is as Figure 6 shown, and the infrared spectra of the CO2 reduction intermediate products of the Cu catalyst at different potentials are as Figure 7 shown, and the infrared spectra of the CO2 reduction intermediate products of the AgCu alloy catalyst at different potentials are as Figure 8 shown, and the product distribution diagrams of the Ag / CuO catalyst at different depths are as Figure 9 shown. It can be seen that the longitudinal scanning design of the present invention: the combination of the zero-gap structure and the stepping motor realizes in-situ monitoring in the depth direction of the catalyst layer, and the combined design of the ZnSe window and the anti-corrosion coating improves the signal intensity and stability, and finally can realize real-time and high-resolution monitoring of the longitudinal substance distribution in the catalyst layer.

[0050] The above is a specific description of the preferred embodiment of the present invention, but the present invention is not limited to the described embodiment. Those skilled in the art can also make various equivalent deformations or substitutions without departing from the spirit of the present invention, and these equivalent deformations or substitutions are all included within the scope defined by the claims of this application.

Claims

1. A longitudinal spatially resolved in-situ infrared electrolytic cell device for electrocatalytic testing, characterized in that: It includes an electrolytic cell body, a micron-level stepping system, an optical system, an electrochemical system, a gas and liquid system, a control platform, a spectral analysis module, a mass spectrometer, and a fluid simulation module.

2. The longitudinal spatial resolution in-situ infrared electrolytic cell device for electrocatalytic testing according to claim 1, characterized in that: The electrolytic cell body comprises a PTFE cell body, which comprises an anode slot and a cathode slot, an anode insulating gasket, an anode perforated electrode plate, a membrane electrode, a cathode perforated electrode plate, and a cathode insulating gasket are sequentially arranged between the anode slot and the cathode slot, a ZnSe window is plated on the inner wall of the cathode slot, and the anode slot and the cathode slot are connected by fixing screws and fixing nuts.

3. The longitudinal spatial resolution in-situ infrared electrolytic cell device for electrocatalytic testing according to claim 2, characterized in that: The micron-level stepping system is composed of a two-dimensional stepping motor and a high-precision displacement sensor. The electrolytic cell body is fixed on a two-dimensional platform of the two-dimensional stepping motor. The two-dimensional stepping motor drives the electrolytic cell body to move longitudinally at micron level along a direction perpendicular to the membrane electrode. The high-precision displacement sensor transmits the displacement data to the electrochemical system, and the electrochemical system transmits the displacement data to the control platform.

4. The longitudinal spatial resolution in-situ infrared electrolytic cell device for electrocatalytic testing according to claim 3, characterized in that: The optical system consists of an infrared light source and a detector. The infrared light source irradiates the ZnSe window vertically. The detector collects infrared signals of longitudinal depth in a reflection mode. The spectral data detected by the detector is transmitted to the control platform.

5. The longitudinal spatial resolution in-situ infrared electrolytic cell device for electrocatalytic testing according to claim 4, characterized in that: The electrochemical system consists of an electrochemical workstation and a platinum counter electrode / reference electrode. The platinum counter electrode is connected to the membrane electrode. The electrochemical workstation controls the reaction potential through a three-electrode system, records the current-voltage curve in real time, and transmits the voltage-current data to the control platform.

6. The longitudinal spatial resolution in-situ infrared electrolytic cell device for electrocatalytic testing according to claim 5, characterized in that: The gas and liquid system consists of a CO2 mass flow controller and an electrolyte circulation pump. CO2 gas is input from the cathode tank inlet, and the electrolyte is input from the anode tank inlet. The mass spectrometer analyzes the mass spectrum data of the product gas in real time and transmits it to the control platform.

7. A longitudinal spatial resolution in-situ infrared electrolytic cell device for electrocatalytic testing according to claim 6, characterized in that: The control platform synchronizes displacement data with voltage and current signals, integrates infrared spectrum data, mass spectrum data, voltage and current data, and triggers the movement of the two-dimensional stepper motor; the spectral analysis module processes the original infrared signal, imports the time-position marked spectral data from the control platform, and outputs a spatial concentration gradient map of the longitudinal material, that is, a longitudinal material distribution thermal map; the fluid simulation module simulates the electrolyte flow and mass transfer process through the data of the control platform and the spectral analysis module, optimizes the cell structure, and predicts the influence of the mass transfer boundary layer on the signal.

8. The longitudinal spatial resolution in-situ infrared electrolytic cell device for electrocatalytic testing according to claim 3, characterized in that: The cathode slot side adopts a wedge-shaped extension method, and an observation port is opened on the cathode slot bracket, and the outside of the observation port is sealed by a ZnSe window; the anode slot adopts a corresponding wedge-shaped extension but retains the side wall to meet the mass transfer requirements of the corresponding cathode reaction side.

9. The longitudinal spatial resolution in-situ infrared electrolytic cell device for electrocatalytic testing according to claim 2, characterized in that: The anode perforated electrode plate and the cathode perforated electrode plate are copper-based porous plates, and the membrane electrode is a detachable carrier with a catalyst layer to be tested coated on the surface.

10. The longitudinal spatial resolution in-situ infrared electrolytic cell device for electrocatalytic testing according to claim 2, characterized in that: The material of the ZnSe window is a ZnSe material with silicon nitride deposited on the surface.

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