Dynamic imaging method for active sites of catalyst in electro-catalysis process

Abstract

The invention belongs to the field of dynamic imaging, and particularly relates to a dynamic imaging method for catalyst active sites in an electro-catalysis process, which comprises the following steps: a white light LED irradiates a sample in an electrolytic tank after being focused by a ten-fold objective lens, and light transmitting the sample sequentially passes through a long-focus hundred-fold objective lens and a spectroscope to respectively enter a spectrograph and a camera; the function generator outputs a TTL signal to a computer while outputting an electric pulse signal to a tested sample in the electrolytic tank; the computer modulates the TTL signal, the camera and the spectrograph perform data acquisition based on the modulated signal, and the computer records and stores the acquired data. In-situ detection of the electro-catalysis process is achieved in an optical imaging mode, and active site distribution and the kinetic process of catalytic reaction can be clearly distinguished.

Description

Technical Field

[0001] The present invention belongs to the field of kinetic imaging, and more specifically, it is a method for kinetic imaging of catalyst active sites during the electrocatalytic process. Background Art

[0002] With the increasing demand for energy, traditional fossil fuels are facing an increasingly depleted crisis due to overexploitation, and at the same time, serious environmental pollution problems also accompany it. Currently, people are turning their attention to clean energy, including new energy sources such as wind energy, solar energy, and hydrogen energy. Electrocatalysis plays an important role in the fields of clean energy utilization, environmental protection, energy conversion, and storage. The electrocatalytic reaction process is very complex and usually involves multi-electron and multi-proton transfer processes. The study of electrocatalytic reaction kinetics and mechanisms is very important and challenging for electrocatalysis. Taking water splitting as an example, the development of highly efficient catalysts is the focus of researchers. However, the performance of catalysts is currently mostly measured by ex-situ characterization methods. For example, the performance of catalysts is mainly judged by the hydrogen evolution reaction onset potential, and the general detection technology is linear sweep voltammetry testing, which gives the overall current-voltage value of the system and cannot distinguish the differences in the local distribution on the catalyst. Therefore, the development of efficient and simple in-situ detection technologies can help obtain the performance of relevant materials, point the way for material development, and promote the development of new energy technologies towards the goals of better efficiency and higher stability. Optical detection technologies, due to their advantages of high sensitivity, high resolution, easy instrumentization, system compatibility, non-interference, and non-destructiveness, are expected to play an important role in the field of energy detection. Therefore, studying the distribution of active sites on the catalyst surface through optical imaging can not only provide a visual evaluation method for the development of catalysts but also provide an in-situ detection basis for the full play of catalyst performance.

[0003] Currently, the in-situ characterization technologies commonly used in electrocatalysis include: Raman and infrared spectroscopy for real-time study of reaction intermediate species and the structural changes of electrocatalysts; electrochemical impedance spectroscopy for real-time study of the electron transfer process involved in electrocatalysts during electrocatalytic reactions. Although these in-situ characterization technologies can study the valence states and structural changes of reaction intermediate species and electrocatalysts in real time, these technologies are all (quasi)-steady-state tests in electrocatalytic tests, and many important processes in electrocatalytic reactions occur on the nanosecond time scale. Therefore, transient kinetic processes occurring on a shorter time scale (such as the nanosecond order) cannot be studied. Summary of the Invention

[0004] The purpose of the present invention is to provide a method for kinetic imaging of catalyst active sites during the electrocatalytic process to overcome the above-mentioned defects.

[0005] The technical solution adopted by the present invention to achieve the above purpose is:

[0006] A kinetic imaging system for catalyst active sites in the electrocatalytic process, comprising: a computer, an electrocatalytic module and a test module respectively connected thereto, wherein,

[0007] The computer is used to modulate the TTL signal sent by the electrocatalytic module, control the test module to collect data, and record the collected data;

[0008] The electrocatalytic module is used to output an electrical pulse signal to the sample to be tested and output a TTL signal to the computer;

[0009] The test module is used to collect data of the sample to be measured according to the signal output by the computer.

[0010] The electrocatalytic module includes: an electrolytic cell, a function generator, an oscilloscope and a multimeter. Among them, the pulse voltage signal output by the function generator is connected to the sample to be tested in the electrolytic cell through a BNC cable, the negative pole is connected to the sample to be tested, and the positive pole is connected to the counter electrode; the sample to be tested and the reference electrode are connected to the multimeter through a wire, and the negative pole of the BNC cable is also connected to the oscilloscope through a current probe, and the function generator is also connected to the computer.

[0011] The test module includes: an LED white light source, a long-focus hundred-fold objective lens, a beam splitter, a camera and a spectrometer. Among them, the white light emitted by the LED white light source is focused by a ten-fold objective lens and then irradiated on the sample to be tested in the electrolytic cell, and then the light transmitted through the sample is collected by the long-focus hundred-fold objective lens for imaging. A part of the light enters the spectrometer after passing through the beam splitter, and the other part of the light enters the camera. Both the spectrometer and the camera are connected to the computer.

[0012] A method for kinetic imaging of catalyst active sites in the electrocatalytic process, comprising the following steps:

[0013] The white light of the white light LED is focused by a ten-fold objective lens and then irradiated on the sample in the electrolytic cell. The light transmitted through the sample sequentially passes through the long-focus hundred-fold objective lens and the beam splitter and enters the spectrometer and the camera respectively;

[0014] While the function generator outputs an electrical pulse signal to the sample to be measured in the electrolytic cell, it outputs a TTL signal to the computer;

[0015] The computer modulates the TTL signal, and the camera and the spectrometer collect data based on the modulated signal. The computer records and saves the collected data.

[0016] The electrical pulse signal and the TTL signal output by the function generator both have a period of 200 ms and a pulse width of 100 ms.

[0017] The computer converts the TTL signal with a period of 200 ms and a pulse width of 100 ms into a signal with a period of 2 ms and a pulse width of 1 ms.

[0018] Both the camera and the spectrometer perform data acquisition at a period of 2 ms.

[0019] The present invention has the following beneficial effects and advantages:

[0020] The present invention can study the transient kinetic process during the electrocatalytic process and the distribution of active sites on the catalyst surface in the millisecond to second order of magnitude. Description of the Drawings

[0021] Figure 1 It is a schematic diagram of this test method.

[0022] Figure 2 It is a schematic diagram of the ultraviolet-visible absorption spectrum of MOS2 in Example 1.

[0023] Figure 3 It is a schematic diagram of the absorption spectrum of MOS2 in Example 1.

[0024] Figure 4 It is a schematic diagram of the kinetic imaging result of Pt-MOS2 in Example 1. Detailed Embodiments

[0025] The following further describes the present invention in detail with reference to the drawings and embodiments.

[0026] A kinetic imaging system for catalyst active sites during the electrocatalytic process consists of a computer, an electrocatalytic module, and each test module. The signals output by the electrocatalytic module and the test module are collected and processed through the Labview program. The electrocatalytic module includes an electrolytic cell, a function generator, an oscilloscope, and a multimeter; the test module includes an LED white light source, a long-focus 100x objective lens, a beam splitter, a camera, and a spectrometer;

[0027] The object of the present invention is achieved through the following solutions.

[0028] 1. The feature of the test method of the present invention is that in the electrocatalytic module: the function generator outputs a pulsed voltage signal through a BNC cable, the negative pole is connected to the sample to be measured in the electrolytic cell, the positive pole is connected to the counter electrode, the sample to be measured and the reference electrode are connected to the multimeter through wires, and the negative pole of the BNC cable is connected to the oscilloscope through a current probe;

[0029] 2. The feature of the test method of the present invention is that in the test module: when the function generator outputs a voltage to the sample to be measured, it synchronously outputs a TTL pulsed signal, the signal is modulated through a self-programmed program, and the modulated pulsed signal is output to the camera and the spectrometer to trigger the camera and the spectrometer to perform data acquisition, and the acquired data is transmitted back to the program for processing and storage;

[0030] See Figure 1, in this embodiment, the test method consists of a computer, an electrocatalysis module, and each test module. The signals output by the electrocatalysis module and the test module are collected and processed through the Labview program. Among them, the electrocatalysis module: the function generator outputs a pulsed voltage signal through a BNC cable. The negative pole is connected to the sample to be tested in the electrolytic cell, and the positive pole is connected to the counter electrode. The sample to be tested and the reference electrode are connected to the multimeter through wires, and the negative pole of the BNC cable is connected to the oscilloscope through a current probe; the test module: when the function generator outputs a voltage to the sample to be tested, it synchronously outputs a TTL pulsed signal. The signal is modulated through a self-programmed program, and the modulated pulsed signal is output to the camera and the spectrometer, triggering the camera and the spectrometer to collect data. The collected data is transmitted back to the program for processing and storage.

[0031] See Figure 1 , after the equipment is connected, the white light LED is focused by the objective lens and irradiated on the sample, and then the light transmitted through the sample is collected by the objective lens for imaging. A part of the light enters the spectrometer after passing through the beam splitter, and the other part of the light enters the camera. The image magnified by the objective lens is observed through the camera; when the function generator simultaneously outputs an electrical pulsed signal with a period of 200 ms (pulse width 100 ms) and a TTL signal to the sample and the acquisition program in the electrolytic cell, after the program receives the TTL signal, it converts the signal into a signal with a period of 2 ms (pulse width 1 ms) and outputs it to the camera and the spectrometer. The camera and the spectrometer collect data at a period of 2 ms, and the collected data is recorded and stored by the program.

[0032] Example 1:

[0033] All the materials of the reagents required for the experiment were purchased from the market. To verify the feasibility of the experimental equipment, the electrocatalysis of MOS2 with detailed reports was selected for testing. The active sites of the MOS2 catalyst are located at the edge positions, so triangular MOS2 was selected for testing and verification. First, Figure 2 is the ultraviolet-visible absorption spectrum of MOS2, and its characteristic absorption peaks are 610 nm and 650 nm. After connecting the equipment in the Figure 1 way, the MOS2 sample was placed in an electrolytic cell containing 0.5 M H2SO4 electrolyte solution for testing. Figure 3 is the absorption spectrum during the reaction process of the MOS2 catalyst, corresponding to the position of the characteristic absorption peaks of MOS2 in Figure 2 , indicating that the device of this patent can perform spectral detection on the catalytic reaction process. According to the position of the absorption peak, a band-pass filter with a wavelength of 650 nm was selected for kinetic imaging testing. Figure 4 a is the bright-field photo of Pt-MOS2 triangle (transferring metallic platinum on the triangle). Figure 4b is the kinetic imaging image of Pt-MOS2 collected at 650 nm under 450 nm pulsed excitation light (period 200 ms). The position of platinum does not weaken, but instead the signal strengthens. Figure 4 c is the kinetic imaging image of Pt-MOS2 collected at 650 nm under electrocatalytic conditions. There is an obvious weakening at the position of platinum. Since the catalytic performance of platinum is superior to that of MOS2, the reaction at the position of platinum is faster and more electrons are consumed, resulting in a weaker signal in the signal imaging. Figure 4 d is the reaction current distribution diagram of the Pt-MOS2 triangle in electrocatalysis. The current density at the position of platinum is higher, which also indicates that the active sites are distributed at the position of platinum.

Claims

1. A kinetic imaging system for catalyst active sites in the electrocatalytic process, characterized in that, Comprising: A computer, an electrocatalysis module and a test module respectively connected thereto, wherein The computer is configured to modulate the TTL signal sent by the electrocatalysis module, control the test module to perform data acquisition, and record the acquired data; The electrocatalysis module is configured to output an electrical pulse signal to the sample to be measured and output a TTL signal to the computer; The test module is configured to acquire the data of the sample to be measured according to the signal output by the computer.

2. The kinetic imaging system for catalyst active sites in the electrocatalytic process according to claim 1, characterized in that, The electrocatalysis module includes: an electrolytic cell, a function generator, an oscilloscope and a multimeter. Among them, the pulse voltage signal output by the function generator is connected to the sample to be measured in the electrolytic cell through a BNC cable, the negative pole is connected to the sample to be measured, and the positive pole is connected to the counter electrode; the sample to be measured and the reference electrode are connected to the multimeter through a wire, and the negative pole of the BNC cable is also connected to the oscilloscope through a current probe, and the function generator is also connected to the computer.

3. The kinetic imaging system for catalyst active sites in the electrocatalytic process according to claim 1, characterized in that, The test module includes: an LED white light source, a long focal length hundred-fold objective lens, a beam splitter, a camera and a spectrometer. Among them, the white light emitted by the LED white light source is focused by a ten-fold objective lens and then irradiated on the sample to be measured in the electrolytic cell, and then the light transmitted through the sample is collected by the long focal length hundred-fold objective lens for imaging. A part of the light enters the spectrometer after passing through the beam splitter, and the other part of the light enters the camera. Both the spectrometer and the camera are connected to the computer.

4. A kinetic imaging method for catalyst active sites in the electrocatalytic process, characterized in that, Including the following steps: The white light emitted by the white light LED is focused by a ten-fold objective lens and then irradiated on the sample in the electrolytic cell. The light transmitted through the sample sequentially passes through the long focal length hundred-fold objective lens and the beam splitter and enters the spectrometer and the camera respectively; While the function generator outputs an electrical pulse signal to the sample to be measured in the electrolytic cell, it outputs a TTL signal to the computer; The computer modulates the TTL signal, and the camera and the spectrometer perform data acquisition based on the modulated signal. The computer records and stores the acquired data.

5. The kinetic imaging method for catalyst active sites in the electrocatalytic process according to claim 4, characterized in that, The periods of the electrical pulse signal and the TTL signal output by the function generator are both 200 ms, and the pulse widths are both 100 ms.

6. The kinetic imaging method for catalyst active sites in the electrocatalytic process according to claim 4, characterized in that, The computer converts the TTL signal with a period of 200 ms and a pulse width of 100 ms into a signal with a period of 2 ms and a pulse width of 1 ms.

7. The kinetic imaging method for catalyst active sites in the electrocatalytic process according to claim 4, characterized in that, Both the camera and the spectrometer perform data acquisition at a period of 2 ms.

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