A method for online detection of hydrogen production by water electrolysis using in-situ time-of-flight mass spectrometry

Abstract

This invention discloses an in-situ time-of-flight mass spectrometer (TOF-MS) method for online detection of hydrogen production via water electrolysis. The method utilizes a hollow, sealed container, an electrochemical cell, a first switching valve, a vacuum pump, a needle valve, a second switching valve, and a TOF-MS. The detection process involves adding a catalyst for water electrolysis to the electrochemical cell, followed by the addition of purified water. A voltage is applied to the positive and negative electrodes to initiate the water electrolysis reaction. Simultaneously, the first and second switching valves, the vacuum pump, and the needle valve are opened. The hydrogen gas produced by water electrolysis enters the ionization region of the TOF-MS through a connecting pipeline. The ionized hydrogen ions are transported downwards to the mass analyzer and are finally detected. This method can monitor the hydrogen gas produced during water electrolysis and its changing trends online. It features fast response and high sensitivity.

Description

Technical Field

[0001] This invention patent is mainly used for in-situ real-time monitoring of the changing trends of hydrogen produced during water electrolysis. Specifically, it utilizes a time-of-flight mass spectrometer to monitor the changes in hydrogen during water electrolysis online in real time, and can also compare the efficiency of hydrogen production using different catalysts based on the hydrogen change trends. It features fast detection speed and high sensitivity. Background Technology

[0002] Time-of-flight mass spectrometry (TOF-MS) offers advantages such as rapid analysis speed, low fragment ion content, and easy spectral identification. It eliminates the need for complex sample pretreatment and is widely used for the rapid detection of VOCs, SVOCs, and chemical warfare agents in the environment. The on-site continuous injection method, combined with the instrument's internal mass calibration and quantitative calibration system, enables precise qualitative and quantitative analysis of samples. The main principle of water electrolysis for hydrogen production is that water molecules are dissociated under the influence of direct current to generate oxygen and hydrogen, which are then released from the anode and cathode of the electrolyzer, respectively. Water electrolysis is a highly efficient and clean hydrogen production technology. Its process is simple, and the product purity is high, typically reaching 99.9% for both hydrogen and oxygen, making it one of the most promising technologies for large-scale hydrogen production.

[0003] Using time-of-flight mass spectrometry and in-situ sample introduction, a simple, rapid, and accurate qualitative and quantitative analytical method was established for in-situ real-time monitoring of the changing trends of hydrogen produced during water electrolysis. This method can distinguish the differences between different catalysts and reaction materials, and has guiding significance for the synthesis of catalysts.

[0004] This invention patent is an instrument that combines an electrochemical reaction cell with a time-of-flight mass spectrometer, enabling the qualitative or quantitative analysis of gaseous or volatile intermediate and final products of electrochemical reactions within milliseconds during dynamic potential scanning. It can be applied to electrocatalysis and in-situ battery testing, and is an important tool for studying electrochemical reaction mechanisms, rapidly screening, and evaluating electrochemical reaction materials and catalysts. Summary of the Invention

[0005] The purpose of this invention is to provide a method for online detection of hydrogen production via water electrolysis using in-situ time-of-flight mass spectrometry (TOF-MS), primarily for in-situ real-time monitoring of the changing trends of hydrogen produced during water electrolysis. Specifically, it utilizes a TOF-MS to monitor the changes in hydrogen during water electrolysis in real-time.

[0006] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0007] A method for online detection of hydrogen production by water electrolysis using in-situ time-of-flight mass spectrometry, the apparatus of which includes a hollow sealed container, an electrochemical cell, a first switching valve, a pump, a needle valve, a second switching valve, and a time-of-flight mass spectrometer;

[0008] The electrochemical cell is a hollow, sealed container. Two through holes are provided on the top and bottom surface of the container. The two through holes are the positive electrode through hole and the negative electrode through hole, respectively. A positive electrode is inserted into the positive electrode through hole and a negative electrode is inserted into the negative electrode through hole. The electrochemical cell is placed inside the hollow, sealed container. A gas outlet is provided on one side of the hollow, sealed container. The gas outlet is connected to the time-of-flight mass spectrometer through a first switching valve and a needle valve arranged in sequence on the connecting pipeline. A branch pipeline is provided on the pipeline between the first switching valve and the needle valve. One end of the branch pipeline is connected to the pipeline between the first switching valve and the needle valve through a tee connector. The other end of the branch pipeline is connected to the atmosphere through a second switching valve and a pump.

[0009] The specific process of the method is as follows: a catalyst for hydrogen production through water electrolysis is added to an electrochemical cell, followed by pure water. A voltage is applied to the positive and negative electrodes to initiate the hydrogen production reaction. Simultaneously, the first and second switching valves, the vacuum pump, and the needle valve are opened. The hydrogen gas produced by water electrolysis enters the ionization region of the time-of-flight mass spectrometer through a connecting pipeline. The ionized hydrogen ions are transported downwards into the mass analyzer and finally detected. Excess gas is discharged through the vacuum pump. The mass spectrometer operates in continuous monitoring mode, enabling real-time, in-situ monitoring of hydrogen gas changes.

[0010] The time-of-flight mass spectrometer uses a vacuum ultraviolet lamp as the ionization source and operates in continuous monitoring mode. The MCP voltage is 2500-2800V, and the gas pressure in the detection zone is 7.00×10⁻⁶. -6 ~3.00×10 -4 Pa; sampling interval is 1s.

[0011] The positive and negative electrodes in the electrochemical cell can be graphite or platinum electrodes, and the voltage applied to the positive and negative electrodes is -2V to +2V.

[0012] Before testing, close the first switch valve, open the second switch valve and needle valve connected to the vacuum pump, and evacuate the pipeline to reduce air interference.

[0013] The intake gas flow rate into the ionization region of the time-of-flight mass spectrometer is controlled by adjusting the needle valve to 1-3 ml / min.

[0014] The air pump has a flow rate of 5 L / min.

[0015] A catalyst is placed in the electrochemical cell for water electrolysis. The efficiency of hydrogen production by different catalysts is tested based on the trend of hydrogen production. The amount of gas entering the ionization zone of the time-of-flight mass spectrometer is controlled by adjusting the needle valve.

[0016] This method can analyze the hydrogen production efficiency of different catalysts and has the advantages of simple structure, high sensitivity and fast response speed. Attached Figure Description

[0017] Figure 1 This is a schematic diagram of the structure of the in-situ time-of-flight mass spectrometer used in this invention for online detection of hydrogen production from water electrolysis; 1—hollow sealed container, 2—first switching valve, 3—vacuum pump, 4—needle valve, 5—time-of-flight mass spectrometer, 6—electrochemical cell, 7—second switching valve.

[0018] Figure 2 The image shows the hydrogen production spectrum obtained from water electrolysis in Example 1. Detailed Implementation

[0019] This invention patent provides a method for online detection of hydrogen production via water electrolysis using in-situ time-of-flight mass spectrometry, such as... Figure 1 As shown, the apparatus used in this method includes a hollow sealed container 1, an electrochemical cell 6, a first switching valve 2, a vacuum pump 3, a needle valve 4, a second switching valve 7, and a time-of-flight mass spectrometer 5.

[0020] The electrochemical cell 6 is a hollow, sealed container. Two through holes are provided on the top and bottom surface of the container. The two through holes are the positive electrode through hole and the negative electrode through hole, respectively. A positive electrode is inserted into the positive electrode through hole and a negative electrode is inserted into the negative electrode through hole. The electrochemical cell 6 is placed inside a hollow, sealed container 1. A gas outlet is provided on one side of the hollow, sealed container 1. The gas outlet is connected to the time-of-flight mass spectrometer 5 through a first switching valve 2 and a needle valve 4 arranged in sequence on the connecting pipeline. A branch pipeline is provided on the pipeline between the first switching valve 2 and the needle valve 4. One end of the branch pipeline is connected to the pipeline between the first switching valve 2 and the needle valve 4 through a tee connector. The other end of the branch pipeline is connected to the atmosphere through a second switching valve 7 and a vacuum pump 3.

[0021] The specific detection process of this method is as follows: a catalyst for hydrogen production through water electrolysis is added to the electrochemical cell 6, followed by pure water. A voltage is applied to the positive and negative electrodes to initiate the hydrogen production reaction. Simultaneously, the first switch valve 2, the second switch valve 7, the vacuum pump 3, and the needle valve 4 are opened. The hydrogen gas generated by water electrolysis enters the ionization region of the time-of-flight mass spectrometer through the connecting pipeline. The ionized hydrogen ions are transported downwards into the mass analyzer and finally detected. Excess gas is discharged through the vacuum pump 3. The mass spectrometer operates in continuous monitoring mode, enabling real-time, in-situ monitoring of hydrogen gas changes.

[0022] The intake air volume into the ionization region of the time-of-flight mass spectrometer 5 is controlled by adjusting needle valve 4 to a value of 1.

[0023] -3ml / min.

[0024] The time-of-flight mass spectrometer 5 uses a vacuum ultraviolet lamp as the ionization source and operates in continuous monitoring mode. The MCP voltage is 2500-2800V, and the gas pressure in the detection zone is 7.00×10⁻⁶. -6 ~3.00×10 -4Pa; sampling interval is 1s.

[0025] The positive and negative electrodes in electrochemical cell 6 can be graphite or platinum electrodes, and a voltage of -2V to +2V is applied to the positive and negative electrodes. The pumping speed is 5L / min.

[0026] Before testing, close the first switch valve 2, open the second switch valve 7 and needle valve 4 connected to the vacuum pump 3, and evacuate the pipeline to reduce air interference.

[0027] Example 1

[0028] 1g of platinum-carbon PT60% catalyst (Suzhou Shengernuo Technology Co., Ltd.) was placed in the electrochemical cell, along with 2ml of purified water. Positive and negative electrodes, both graphite rod electrodes, were inserted into the two through-holes of the electrochemical cell. The applied voltage to the electrodes was set by the electrochemical workstation, ranging from -2V to +2V, for 3 minutes, with a voltage change step of 0.022V / s, for 5 cycles. Simultaneously, the vacuum pump and needle valve were turned on, and the gas intake was controlled at 1ml / min by adjusting the needle valve to maintain the ionization zone pressure at approximately 1Pa. The time-of-flight mass spectrometer used a vacuum ultraviolet lamp ionization source, operating in continuous monitoring mode, with an MCP voltage of 2500V and a detection zone pressure of 4.00×10⁻⁶. -5 Pa; the sampling interval is 1s, and the trend of hydrogen gas change generated by water electrolysis is monitored in real time. The detection results are as follows: Figure 2 As shown, changes in hydrogen production could be detected in all five cycles.

Claims

1. A method for online detection of hydrogen production by water electrolysis using in-situ time-of-flight mass spectrometry, characterized in that: The apparatus used in this method includes a hollow sealed container (1), an electrochemical cell (6), a first switching valve (2), a vacuum pump (3), a needle valve (4), a second switching valve (7), and a time-of-flight mass spectrometer (5). The electrochemical cell (6) is a hollow sealed container. Two through holes are provided on the top bottom surface of the container. The two through holes are positive electrode through holes and negative electrode through holes, respectively. A positive electrode is inserted into the positive electrode through hole and a negative electrode is inserted into the negative electrode through hole. The electrochemical cell (6) is placed in a hollow sealed container (1). A gas outlet is provided on one side of the hollow sealed container (1). The gas outlet is connected to the time-of-flight mass spectrometer (5) through the first switch valve (2) and the needle valve (4) arranged in sequence on the connecting pipeline. A branch pipeline is set on the pipeline between the first switch valve (2) and the needle valve (4). One end of the branch pipeline is connected to the pipeline between the first switch valve (2) and the needle valve (4) through a tee connector. The other end of the branch pipeline is connected to the atmosphere through the second switch valve (7) and the air pump (3). The specific process of the method is as follows: a catalyst for producing hydrogen by electrolysis of water is added to the electrochemical cell (6), then pure water is added, and a voltage is applied to the positive and negative electrodes to produce hydrogen by electrolysis of water. At the same time, the first switch valve (2), the second switch valve (7), the vacuum pump (3) and the needle valve (4) are opened. The hydrogen gas produced by electrolysis of water enters the ionization region of the time-of-flight mass spectrometer through the connecting pipeline. The hydrogen ions produced by ionization are transported downward to the mass analyzer and finally detected. Excess gas is discharged through the vacuum pump (3). The mass spectrometer works in continuous monitoring mode and can monitor the change trend of hydrogen gas in real time in situ.

2. The method for online detection of hydrogen production by water electrolysis using in-situ time-of-flight mass spectrometry according to claim 1, characterized in that: The time-of-flight mass spectrometer (5) uses a vacuum ultraviolet lamp as the ionization source and operates in continuous monitoring mode. The MCP voltage is 2500-2800V, and the gas pressure in the detection zone is 7.00×10⁻⁶. -6 ~3.00×10 -4 Pa; sampling interval is 1s.

3. The method for online detection of hydrogen production by water electrolysis using in-situ time-of-flight mass spectrometry according to claim 1, characterized in that: The positive and negative electrodes in the electrochemical cell (6) can be graphite or platinum electrodes, and the voltage applied to the positive and negative electrodes is -2V to +2V.

4. The method for online detection of hydrogen production by water electrolysis using in-situ time-of-flight mass spectrometry according to claim 1, characterized in that: Before testing, close the first switch valve (2), open the second switch valve (7) and needle valve (4) connected to the vacuum pump (3), and evacuate the pipeline to reduce air interference.

5. The method for online detection of hydrogen production by water electrolysis using in-situ time-of-flight mass spectrometry according to claim 3, characterized in that: Adjust the needle valve (4) to control the gas flow rate entering the ionization zone of the time-of-flight mass spectrometer (5) to be 1-3 ml / min.

6. The method for online detection of hydrogen production by water electrolysis using in-situ time-of-flight mass spectrometry according to claim 4, characterized in that: The air pump has a flow rate of 5 L / min.

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