A device and method for real-time measurement of pH on the surface of a photoelectrode.

Abstract

This invention discloses a device and method for real-time measurement of the pH value on the surface of a photoelectrode, belonging to the field of photoelectrochemical technology. The device utilizes a real-time pH-sensitive fluorescent probe to correlate light intensity, time, and pH, enabling real-time measurement of the pH value on the photoelectrode surface. This further allows for the visualization of photoelectrocatalytic activity, revealing the activity of the photoelectrode and the spatial distribution of active sites, thus providing a better evaluation of photocatalytic performance. As a method and device for real-time measurement of pH distribution on the electrode surface during photoelectrochemical water splitting, this invention can be applied to research in fields such as solar-powered hydrogen production.

Description

Technical Field

[0001] This invention application relates to the field of photoelectrochemical technology, specifically to a device and method for real-time measurement of pH on the surface of a photoelectrode. Background Technology

[0002] With the increasing severity of the energy crisis and environmental problems, the development of new energy sources to gradually replace fossil fuels and improve the existing energy supply structure is imperative. In recent years, photoelectrochemical water splitting, as an important method of solar-powered hydrogen production, has attracted widespread research from scholars worldwide. Utilizing light to reduce water or carbon dioxide into hydrogen through a catalyst can effectively convert electrical energy into chemical energy while mitigating greenhouse gas emissions, thus better addressing both energy and environmental challenges. To improve hydrogen production efficiency, selecting a high-performance photocatalyst is crucial for the industrial application of solar-powered hydrogen production and remains a current research hotspot and challenge. Accurately determining the performance of a photoelectrochemical system is closely related to the pH environment of the photoelectrode surface. Therefore, measuring the pH changes on the photoelectrode surface to visualize photoelectrocatalytic activity and reveal the magnitude and spatial distribution of electrocatalytic activity is of paramount importance.

[0003] The anodic process of photoelectrochemical water splitting is an oxygen evolution reaction involving four holes and four protons. The slow kinetics of this reaction are a major limiting factor for low photoelectrochemical hydrogen production efficiency. The photoelectrochemical water splitting oxygen evolution reaction is accompanied by changes in the pH of the electrode surface. By studying the pH distribution on the photoelectrode surface and its changes over time, the oxygen evolution rate and photoelectrocatalytic performance of the electrode surface can be investigated. Currently, related research focuses more on the design and performance characterization of the photoelectrode, but research on the pH changes on the electrode surface during photoelectrochemical oxygen evolution is relatively limited. Therefore, this patent proposes a method and apparatus for real-time measurement of the pH distribution on the electrode surface during photoelectrochemical water splitting, which can be applied to research in fields such as solar hydrogen production. Summary of the Invention

[0004] To address or partially address the problems existing in related technologies, this invention application provides a device and method for real-time measurement of the pH of a photoelectrode surface.

[0005] The first aspect of this invention provides a device for real-time measurement of pH on the surface of a photoelectrode, comprising: an electrochemical fluorescence microscope, an electrochemical measurement system, a first light source, a second light source, a spectrometer, a visual CCD detection device, a data acquisition device, and a computer;

[0006] The electrochemical fluorescence microscope includes an objective lens, a semi-reflective lens, a collimating lens, a long-pass filter, and a spectroscope. The spectrometer and visual CCD detection device are positioned above the microscope. The electrochemical measurement system includes an electrolytic cell and a potentiostat. The electrolytic cell is located directly below the electrochemical fluorescence microscope and includes an electrolytic cell base, an electrolytic cell reaction chamber, a quartz glass cover, a working electrode, a reference electrode, and an auxiliary electrode. The working electrode, reference electrode, and auxiliary electrode are disposed within the electrolytic cell. The working electrode is located at the bottom of the electrolytic cell. The working electrode, reference electrode, and auxiliary electrode are each connected to the potentiostat. The potentiostat is connected to the input terminal of a data acquisition device, and the output terminal of the data acquisition device is connected to a computer. The first light source is positioned below the electrolytic cell, and the bottom wall of the electrolytic cell is a light-transmitting wall. The first light source illuminates the lower surface of the working electrode upwards. The second light source is positioned above the electrolytic cell and illuminates the upper surface of the working electrode downwards.

[0007] Furthermore, in addition to the original optical elements, the electrochemical fluorescence microscope adds a semi-reflective lens, a collimating lens, a long-pass filter, and a beam splitter above the objective lens to obtain the required light source.

[0008] Furthermore, the long-pass filter is a 510nm long-pass filter, and the beam splitter is a 50:50 beam splitter.

[0009] Furthermore, the first light source is a blue LED light source (wavelength 455nm), which also serves as the excitation source for the electrochemical reaction and fluorescence generated by the excitation photoelectrode.

[0010] Furthermore, the second light source is a white light source.

[0011] Furthermore, the potentiostat controls the potential of the photoelectrode via buttons and software, enabling the measurement of photocurrent changes at different electrodes under the same potential. It also measures the relationship between the pH value and photocurrent on the photoelectrode surface using a pH-sensitive sodium fluorescein probe.

[0012] Furthermore, one end of the spectrometer is connected to an optical fiber tube, and the USB4000 spectrometer is used to convert the optical signal into an electrical signal to detect the fluorescence intensity. The other end of the spectrometer is connected to a computer.

[0013] Furthermore, it also includes a frame, on which the blue LED light source, electrolytic cell, and white light source are mounted.

[0014] A second aspect of this invention provides a method for real-time measurement of pH on the surface of a photoelectrode, comprising the following steps:

[0015] Step 1. Assemble the electrolytic cell and fill the reaction chamber of the electrolytic cell with the appropriate electrolyte;

[0016] Step 2. Fix the electrolytic cell on the frame. The second light source reaches the bottom of the electrolytic cell through the collimating filter, so that the surface of the working electrode of the electrolytic cell is in the same straight line as the first light source. The observed electrode surface image is focused and clear by using CCD vision inspection equipment and computer.

[0017] Step 3. Turn off the second light source and turn on the blue LED light source to excite the photoelectrode to generate an electrochemical reaction and excite the fluorescence signal in the electrolyte, thereby obtaining the fluorescence pattern on the electrode surface;

[0018] Step 4. Connect the working electrode, reference electrode, and auxiliary electrode to the potentiostat, connect the potentiostat to the input terminal of the data acquisition device, and connect the output terminal of the data acquisition device to the computer.

[0019] Step 5. Turn on the potentiostat, set the same working time and the same working potential, and start measuring the photocurrent. You can observe the relationship curve between the photocurrent and the photoelectrochemical reaction time in real time.

[0020] Step 6. Turn on the spectrometer, set the sampling speed and total measurement time, measure the fluorescence spectrum, and simultaneously use a CCD camera to record the fluorescence image and fluorescence spectrum on the electrode surface.

[0021] Step 7. After the measurement is completed, turn off the blue LED light source, store the data, and unload the electrolytic cell;

[0022] Step 8. Process the obtained fluorescence patterns, fluorescence images, and fluorescence spectra, and calculate the relationship curve between pH and reaction time from the processed images.

[0023] It should be understood that the above general description and the following detailed description are exemplary and explanatory only, and do not limit the scope of this application.

[0024] Beneficial technical effects of the present invention:

[0025] In this invention, during detection, a corresponding electrolyte is filled into the electrolytic cell reaction chamber. The working electrode, reference electrode, and auxiliary electrode are immersed in the electrolyte containing practical pH-sensitive fluorescent probe molecules. A second light source, through a collimating filter, a semi-reflective lens, and an objective lens, reaches the bottom of the electrolytic cell, ensuring that the surface of the working electrode is aligned with the first light source. The first light source is then activated to emit a blue LED light signal. Specifically, the light emitted by the first light source passes through the light-transmitting wall and illuminates the lower surface of the working electrode within the electrolytic cell, exciting the fluorescent light source within the reaction chamber. The second light source illuminates the upper surface of the working electrode downwards. The signal is generated by pressing... A potentiostat controlled by a key and software ensures that a suitable current flows through the working electrode. The fluorescence signal is received by a spectrometer and a visual CCD detection device through an electrolytic cell, objective lens, semi-reflective mirror, 510nm long-pass filter, and spectroscope, and displayed on a computer. The change in fluorescence intensity peak value is measured under the same reaction time and the same potential. The relationship between pH and photoelectrochemical reaction time can be calculated by the relationship between fluorescence intensity peak value and photoelectrochemical reaction time, as well as the relationship between fluorescence intensity peak value and pH. Finally, the pH value on the photoelectrode surface is measured in real time through data processing algorithms, thereby achieving a better evaluation of photocatalytic performance. Attached Figure Description

[0026] Figure 1 This is a schematic diagram of the device structure of the present invention.

[0027] Among them, 100-electrolytic cell, 110-electrolytic cell base, 120-electrolytic cell reaction chamber, 130-quartz glass cover, 140-working electrode, 150-reference electrode, 160-auxiliary electrode, 200-first light source, 300-electrochemical fluorescence microscope, 310-objective lens, 320-semi-reflective lens, 330-collimating lens, 340-long-pass filter, 350-spectrum spectrometer, 400-second light source, 500-spectrometer, 600-visual CCD detection equipment.

[0028] Figure 2 The graph shows the change in fluorescence signal on the patterned BiVO4 electrode surface with photoelectrochemical reaction time at a potential of 1.23 VRHE.

[0029] Figure 3 This is a spectrum showing the change in fluorescence intensity on the patterned BiVO4 electrode surface with photoelectrochemical reaction time at 0.06VRHE.

[0030] Figure 4 This is a graph showing the relationship between the peak fluorescence intensity of a patterned BiVO4 electrode surface and pH under the same electrolyte concentration.

[0031] Figure 5This is a curve showing the change in pH on the patterned BiVO4 electrode surface with photoelectrochemical reaction time at 0.06VRHE. Detailed Implementation

[0032] The alternative embodiments of this application will now be described in more detail with reference to the accompanying drawings. While alternative embodiments of this application are shown in the drawings, it should be understood that this application can be implemented in various forms and should not be limited to the embodiments set forth herein. Rather, these embodiments are provided to make this application more thorough and complete, and to fully convey the scope of this application to those skilled in the art.

[0033] The terminology used in this application is for the purpose of describing particular embodiments only and is not intended to be limiting of the application. The singular forms “a,” “the,” and “the” used in this application and the appended claims are also intended to include the plural forms unless the context clearly indicates otherwise. It should also be understood that the term “and / or” as used herein refers to and includes any or all possible combinations of one or more of the associated listed items.

[0034] The apparatus and method for real-time measurement of pH on the surface of a photoelectrode, as described in this invention, are described in detail below with reference to the accompanying drawings:

[0035] A device for real-time measurement of pH on the surface of a photoelectrode includes: an electrochemical fluorescence microscope, an electrochemical measurement system, a first light source, a second light source, a spectrometer, a visual CCD detection device, a data acquisition device, and a computer;

[0036] The electrochemical fluorescence microscope 300 includes an objective lens 310, a semi-reflective mirror 320, a collimating lens 330, a long-pass filter 340, and a spectrometer 350. The spectrometer 500 and the visual CCD detection device 600 are positioned above the microscope. The electrochemical measurement system includes an electrolytic cell 100 and a potentiostat. The electrolytic cell 100 is located directly below the electrochemical fluorescence microscope 310 and includes an electrolytic cell base 110, an electrolytic cell reaction chamber 120, a quartz glass cover 130, a working electrode 140, a reference electrode 150, and an auxiliary electrode 160. The working electrode 140, the reference electrode 150, and the... An auxiliary electrode 160 is disposed within the electrolytic cell 100. The working electrode is located at the bottom 110 of the electrolytic cell. The working electrode 140, the reference electrode 150, and the auxiliary electrode 160 are respectively connected to a potentiostat. The potentiostat is connected to the input terminal of a data acquisition device, and the output terminal of the data acquisition device is connected to a computer. The first light source 200 is disposed below the electrolytic cell 100. The bottom wall 110 of the electrolytic cell is a light-transmitting wall. The first light source 200 illuminates the lower surface of the working electrode upwards. The second light source 400 is disposed above the electrolytic cell and illuminates the upper surface of the working electrode downwards.

[0037] In one embodiment of the present invention, the electrochemical fluorescence microscope 300, in addition to the original optical elements, has a semi-reflective semi-transparent lens 320, a collimating lens 330, a long-pass filter 340 and a beam splitter 350 added above the objective lens 310 to obtain the desired light source.

[0038] In one embodiment of the present invention, the long-pass filter 340 is a 510nm long-pass filter, and the beam splitter is a 50:50 beam splitter.

[0039] In one embodiment of the present invention, the first light source 200 is a blue LED light source (wavelength 455nm), which also serves as an excitation light source for generating electrochemical reactions and fluorescence by excitation photoelectrodes.

[0040] In one embodiment of the present invention, the second light source 400 is a white light source.

[0041] In one embodiment of the present invention, the potentiostat controls the potential of the photoelectrode by buttons and software, which can obtain the photocurrent changes of different electrodes at the same potential, and measure the relationship between the pH value and photocurrent on the surface of the photoelectrode by using a practical pH-sensitive sodium fluorescein probe.

[0042] In one embodiment of the present invention, one end of the spectrometer 500 is connected to an optical fiber tube, and the optical signal is converted into an electrical signal by a USB4000 spectrometer to detect the fluorescence intensity. The other end of the spectrometer 500 is connected to a computer.

[0043] In one embodiment of the present invention, a frame is also included, on which the blue LED light source 200, the electrolytic cell 100, and the white light source 400 are mounted.

[0044] A method for real-time measurement of pH on the surface of a photoelectrode, based on the aforementioned device for real-time measurement of pH on the surface of a photoelectrode, is characterized by comprising the following steps:

[0045] Step 1. Assemble the electrolytic cell and fill the reaction chamber 120 of the electrolytic cell with the appropriate electrolyte;

[0046] Step 2. Fix the electrolytic cell 100 on the frame. The second light source 400 reaches the bottom 110 of the electrolytic cell through the collimating filter 330, so that the surface of the working electrode 140 of the electrolytic cell is in the same straight line as the first light source 200. The observed electrode surface image is focused and clear by the CCD vision inspection device 600 and the computer.

[0047] Step 3. Turn off the second light source 400, turn on the blue LED light source 200, excite the photoelectrode to generate an electrochemical reaction and excite the fluorescence signal in the electrolyte, and obtain the fluorescence pattern on the electrode surface;

[0048] Step 4. Connect the working electrode 140, the reference electrode 150 and the auxiliary electrode 160 to the potentiostat, connect the potentiostat to the input terminal of the data acquisition device, and connect the output terminal of the data acquisition device to the computer.

[0049] Step 5. Turn on the potentiostat, set the same working time and the same working potential, and start measuring the photocurrent. You can observe the relationship curve between the photocurrent and the photoelectrochemical reaction time in real time.

[0050] Step 6. Turn on the spectrometer 500, set the sampling speed and total measurement time, measure the fluorescence spectrum, and simultaneously use the CCD camera 600 to record the fluorescence image and fluorescence spectrum on the electrode surface.

[0051] Step 7. After the measurement is completed, turn off the blue LED light source 200, store the data, and unload the electrolytic cell 100;

[0052] Step 8. Process the obtained fluorescence patterns, fluorescence images, and fluorescence spectra, and calculate the relationship curve between pH and reaction time from the processed images.

[0053] Reference Figure 2 ,

[0054] Figure 2The image shows the change in fluorescence signal emitted from the patterned BiVO4 electrode surface with photoelectrochemical reaction time at a potential of 1.23 VRHE. As the reaction time progresses, the image darkens, indicating a gradual weakening of the fluorescence signal and a gradual decrease in the pH of the photoelectrode surface. Simultaneously, the contrast between light and dark areas increases as the reaction proceeds. This is because the pH of the BiVO4 electrode surface is lower than that of the blank surface.

[0055] Reference Figure 3 ,

[0056] Figure 3 The graph shows the fluorescence intensity on the patterned BiVO4 electrode surface as a function of photoelectrochemical reaction time at a potential of 0.06VRHE. As the reaction time increases, the fluorescence intensity peak gradually decreases, indicating that the pH at the photoelectrode surface gradually decreases. Simultaneously, as the reaction time increases, the distance between the peaks of the two curves gradually shortens at the same time interval, indicating that the rate of decrease in fluorescence intensity peak value gradually decreases, and the rate of pH decrease also decreases. The oxygen evolution rate at the electrode surface can be calculated from the rate of pH decrease.

[0057] Reference Figure 4 ,

[0058] Figure 4 The figure shows the relationship between the peak fluorescence intensity of the patterned BiVO4 electrode surface and pH under the same electrolyte concentration. To more intuitively reflect the pH value of the electrode surface, the fluorescence intensity of the electrode surface was observed through a series of electrolytes with different pH gradients. As the pH value increases, the intensity of the fluorescence signal emitted by the photoelectrode surface increases, and the relationship between the peak fluorescence intensity and pH is approximately linear.

[0059] Reference Figure 5 ,

[0060] Figure 5 This image shows the fluorescence intensity on a patterned BiVO4 electrode surface as a function of photoelectrochemical reaction time at 0.06 VRHE. Based on the standard curve of fluorescence intensity peak versus pH, the pH corresponding to different peak values ​​in the spectrum can be determined. Then, based on the relationship between fluorescence intensity peak and photoelectrochemical reaction time, the pH relationship with photoelectrochemical reaction time can be calculated, thus visualizing the pH distribution on the electrode surface. The relationship between pH on the patterned BiVO4 electrode surface, fluorescence intensity, and photoelectrochemical reaction time was obtained, and the results are largely consistent with expectations, enabling real-time measurement of the pH value on the BiVO4 photoelectrode surface.

[0061] The working principle and process of this invention:

[0062] In use, the second light source 400 illuminates the bottom wall 110 of the electrolytic cell through the collimating filter 330, the semi-reflective mirror 320, and the objective lens 310, so that the surface of the working electrode 140 of the electrolytic cell is aligned with the first light source 200. The first light source 200 is turned on so that the blue LED light source illuminates the working electrode, exciting a fluorescent light source. The potentiostat is controlled by buttons and software to ensure that a suitable current passes through the working electrode. The fluorescent signal is received by the spectrometer 500 and the visual CCD detection device 600 through the electrolytic cell 100, the objective lens 310, the semi-reflective mirror 320, the 510nm long-pass filter 340, and the spectrometer 350, and displayed on the computer. Finally, the pH value of the photoelectrode surface is measured in real time through data processing algorithms.

[0063] The various embodiments of this invention have been described above. These descriptions are exemplary and not exhaustive, nor are they limited to the disclosed embodiments. Many modifications and variations will be apparent to those skilled in the art without departing from the scope and spirit of the described embodiments. The terminology used herein is chosen to best explain the principles, practical application, or improvement of the technology in the market, or to enable others skilled in the art to understand the embodiments disclosed herein.

Claims

1. A device for real-time measurement of pH on the surface of a photoelectrode, characterized in that, include: Electrochemical fluorescence microscope, electrochemical measurement system, first light source, second light source, spectrometer, visual CCD detection equipment, data acquisition device, and computer; The electrochemical fluorescence microscope (300) includes an objective lens (310), a semi-reflective mirror (320), a collimating lens (330), a long-pass filter (340), and a spectroscope (350). The spectrometer (500) and the visual CCD detection device (600) are located above the microscope. The electrochemical measurement system includes an electrolytic cell (100) and a potentiostat. The electrolytic cell (100) is located directly below the electrochemical fluorescence microscope (300) and includes an electrolytic cell base (110) and an electrolytic cell reaction chamber (120). The electrolytic cell (100) includes a quartz glass cap (130), a working electrode (140), a reference electrode (150), and an auxiliary electrode (160). The working electrode (140), reference electrode (150), and auxiliary electrode (160) are disposed in the electrolytic cell (110). The working electrode is located in the base (110) of the electrolytic cell. The working electrode (140), reference electrode (150), and auxiliary electrode (160) are respectively connected to a potentiostat. The potentiostat is connected to the input terminal of a data acquisition device, and the output terminal of the data acquisition device is connected to a computer. The first light source (200) is located below the electrolytic cell (100). The electrolytic cell base (110) is a light-transmitting wall. The first light source (200) shines upward on the lower surface of the working electrode. The first light source (200) is a blue LED light source with a wavelength of 455nm. It also serves as an excitation light source for generating electrochemical reactions and fluorescence at the excitation photoelectrode. The second light source (400) is positioned above the electrolytic cell and shines downwards onto the upper surface of the working electrode. The second light source (400) is a white light source.

2. The device for real-time measurement of pH on the surface of a photoelectrode according to claim 1, characterized in that, In addition to the original optical elements, the electrochemical fluorescence microscope (300) has a semi-reflective lens (320), a collimating lens (330), a long-pass filter (340), and a beam splitter (350) added above the objective lens (310) to obtain the required light source.

3. The device for real-time measurement of pH on the surface of a photoelectrode according to claim 1, characterized in that, The long-pass filter (340) is a 510nm long-pass filter, and the beam splitter is a 50:50 beam splitter.

4. The device for real-time measurement of pH on the surface of a photoelectrode according to claim 1, characterized in that, The potentiostat controls the potential of the photoelectrode via buttons and software, enabling the measurement of photocurrent changes at the same potential for different electrodes. It also measures the relationship between the pH value and photocurrent on the photoelectrode surface using a pH-sensitive sodium fluorescein probe.

5. The device for real-time measurement of pH on the surface of a photoelectrode according to claim 1, characterized in that, One end of the spectrometer (500) is connected to an optical fiber tube, and the USB4000 spectrometer is used to convert the optical signal into an electrical signal to detect the fluorescence intensity. The other end of the spectrometer (500) is connected to a computer.

6. The device for real-time measurement of pH on the surface of a photoelectrode according to claim 1, characterized in that, It also includes a frame on which the blue LED light source (200), electrolytic cell (100), and white light source (400) are mounted.

7. A method for real-time measurement of pH on the surface of a photoelectrode, based on the apparatus for real-time measurement of pH on the surface of a photoelectrode according to any one of claims 1 to 6, characterized in that, Includes the following steps: Step 1. Assemble the electrolytic cell and fill the reaction chamber (120) of the electrolytic cell with the appropriate electrolyte; Step 2. Fix the electrolytic cell (100) on the frame. The second light source (400) reaches the base (110) of the electrolytic cell through the collimation filter (330), so that the surface of the working electrode (140) of the electrolytic cell is in the same straight line as the first light source (200). The observed electrode surface image is focused and clear by using the CCD vision inspection device (600) and computer. Step 3. Turn off the second light source (400), turn on the blue LED light source (200), excite the photoelectrode to generate an electrochemical reaction and excite the fluorescence signal in the electrolyte to obtain the fluorescence pattern on the electrode surface; Step 4. Connect the working electrode (140), reference electrode (150) and auxiliary electrode (160) to the potentiostat, connect the potentiostat to the input terminal of the data acquisition device, and connect the output terminal of the data acquisition device to the computer. Step 5. Turn on the potentiostat, set the same working time and the same working potential, and start measuring the photocurrent. You can observe the relationship curve between the photocurrent and the photoelectrochemical reaction time in real time. Step 6. Turn on the spectrometer (500), set the sampling speed and total measurement time, measure the fluorescence spectrum, and simultaneously use the CCD camera (600) to record the fluorescence image and fluorescence spectrum on the electrode surface. Step 7. After the measurement is completed, turn off the blue LED light source (200), store the data, and unload the electrolytic cell (100). Step 8. Process the obtained fluorescence patterns, fluorescence images, and fluorescence spectra, and calculate the relationship curve between pH and reaction time from the processed images.

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