Method for improving release efficiency of bubbles on surface of electrode in large-current water electrolysis hydrogen production

Abstract

A method for improving the release efficiency of bubbles on the surface of an electrode in high-current water electrolysis hydrogen production belongs to the technical field of hydrogen energy production, and the specific scheme comprises the following steps: step 1, applying pulse voltage to a proton exchange membrane electrolytic cell for water electrolysis hydrogen production, the applied pulse current being 0.5-2A, and the applied pulse voltage being 1.4-1.6 V; and 2, conveying the electrolyte deionized water to an anode chamber of the proton exchange membrane electrolytic cell so as to initiate an oxidation reaction to prepare hydrogen. According to the pulse dynamic electrolysis technology, the PEMWE high-current hydrogen production performance can be improved by adjusting the power supply mode of the power source. Besides, the voltage during the pulse interval period is zero, and the total energy consumption actually only comprises the electric energy consumption within the pulse voltage applying time, so that the pulse dynamic electrolysis technology has more advantages from the energy consumption perspective. The pulse dynamic electrolysis technology is expected to promote bubble release and relieve the polarization phenomenon in PEMWE high-current hydrogen production, and the hydrogen production efficiency and the energy utilization rate of the system are improved.

Description

Technical Field

[0001] The present invention belongs to the technical field of hydrogen energy production, and specifically relates to a method for improving the bubble release efficiency on the electrode surface in high-current water electrolysis to produce hydrogen, which utilizes a proton exchange membrane electrolyzer (PEM) to enhance the efficiency of high-current hydrogen production. Background Art

[0002] As a secondary energy source, hydrogen has many advantages, such as high energy density, wide range of sources and applications, and adaptability to large-scale energy storage. Using renewable electricity for water electrolysis is widely regarded as a potential and sustainable way to generate clean hydrogen fuel. The existing mainstream alkaline water electrolysis (AWE) technology faces challenges such as gas cross-permeation, high ohmic resistance, low current density and poor dynamic response in application due to the use of diaphragms and alkaline electrolytes. The use of solid polymer-based proton exchange membranes can achieve efficient proton transfer. PEM water electrolysis (PEMWE) technology has attracted much attention because it significantly improves hydrogen production performance while solving these problems. These advantages make PEMWE a promising solution for the conversion and storage of intermittent renewable energy, helping the low-carbon transformation of industry. However, under high current operation, the PEMWE system faces problems such as bubble retention, polarization effect and low energy efficiency, which restricts its further application and promotion. Conventional constant voltage strategies are difficult to effectively solve these problems, especially the accumulation of bubbles on the electrode surface not only hinders ion transfer, but also increases local overvoltage, thereby reducing hydrogen production efficiency. Therefore, there is an urgent need for an efficiency-enhancing technology that can efficiently control bubble behavior to improve the performance of the PEMWE high-current hydrogen production system.

[0003] As a new technical strategy, pulse dynamic electrolysis shows potential in improving bubble release efficiency and alleviating polarization. However, current research on pulse electrolysis of water to produce hydrogen is mainly focused on high-frequency pulse voltages of 3 to 100 kHz. The patent with invention patent publication number CN 114351163 A disclosed in 2022 a method for searching for the optimal duty cycle of the electrolysis hydrogen production voltage. It discloses a method for calculating the efficiency of electrolysis of water to produce hydrogen under different duty cycles. The frequencies involved under different duty cycles are also high-frequency pulse voltages at the kHz level. The active area of ​​the electrolyzer has an important influence on the reaction characteristics and challenges faced by the PEMWE system. The patent with invention patent publication number CN117127195A disclosed in 2023 a method for promoting proton exchange membrane water electrolysis to produce hydrogen. The active area of ​​this patent is 4cm 2The main challenge of small electrolyzers is the slow mass transfer of reactants. The technical solution to this problem is to use pulse voltage to enrich reactants within the higher polarization voltage range (1.75-3.5V) where the electrolysis reaction occurs to improve the transfer efficiency and enhance the hydrogen production effect. However, the reaction characteristics of enlarged electrolyzers are significantly different from those of small electrolyzers. The main problems faced by enlarged electrolyzers are bubble accumulation, polarization effect and low energy efficiency under high current conditions. At present, there is no disclosure of technical solutions to this technical problem in the prior art. Summary of the invention

[0004] Under high current operation, conventional constant voltage electrolysis PEMWE systems face problems such as bubble retention, polarization effect and low energy efficiency, which restricts their further application and promotion. In particular, the accumulation of bubbles on the electrode surface not only hinders ion transfer, but also increases local overvoltage, thereby reducing hydrogen production efficiency. In order to solve the above technical problems, the present invention provides a method for improving the efficiency of bubble release on the electrode surface in high current water electrolysis hydrogen production.

[0005] In order to achieve the above object, the present invention adopts the following technical solutions:

[0006] A method for improving the bubble release efficiency on the electrode surface in high-current water electrolysis to produce hydrogen, comprising the following steps:

[0007] Step 1: Apply pulse voltage to the proton exchange membrane electrolyzer to produce hydrogen by water electrolysis. The membrane electrode area of ​​the proton exchange membrane electrolyzer is 25 cm 2 , the applied pulse voltage range is 1.4-1.6V;

[0008] Step 2: Deionized water of the electrolyte is transported to the anode chamber of the proton exchange membrane electrolyzer, thereby initiating an oxidation reaction to produce hydrogen.

[0009] In step 1, the pulse current applied is 0.5-2A.

[0010] In step 1, the pulse frequency is 0.05 Hz-0.5 Hz, preferably, the pulse frequency is 0.05 Hz-0.1 Hz.

[0011] In step 1, the pulse duty cycle is 10%-90%, preferably, the pulse duty cycle is 10%-20%.

[0012] In step 1, the pulse intermittent voltage is set to the open circuit voltage state of PEMWE hydrogen production. Preferably, the pulse intermittent voltage is set to 0V.

[0013] The proton exchange membrane electrolyzer comprises an electrolyzer and a membrane electrode, wherein the membrane electrode is composed of Pt / C+Nafion 117 membrane+IrO2 catalyst.

[0014] In step 2, the delivery rate of deionized water as the electrolyte is 63.2 mL / min.

[0015] The proton exchange membrane electrolyzer is configured as a serpentine flow channel.

[0016] Compared with the prior art, the present invention has the following beneficial effects:

[0017] The present invention focuses on low-frequency pulse voltage (<1Hz). The pulse dynamic electrolysis technology does not need to change the main structure or electrode material of the constant voltage electrolyzer. The performance improvement of PEMWE high-current hydrogen production can be achieved only by adjusting the power supply mode. In addition, since the voltage is zero during the pulse interval, the total energy consumption actually only includes the power consumption during the pulse voltage application time. Therefore, from the perspective of energy consumption, the pulse dynamic electrolysis technology is more advantageous. The pulse dynamic electrolysis technology is expected to promote bubble release and alleviate polarization in PEMWE high-current hydrogen production, thereby improving the hydrogen production efficiency and energy utilization of the system. The method provided by the present invention has significant advantages in low-energy hydrogen production. Specifically, due to the relaxation effect generated by the periodic pulse intermittent voltage, the growth momentum of microscopic bubbles on the membrane electrode surface is reduced, thereby promoting the desorption of bubbles and the replenishment of reactants, and showing significant advantages in the equilibrium voltage and starting voltage PEMWE reaction stage. Driven by the equilibrium voltage and starting voltage, the hydrogen production rate of the pulse dynamic electrolysis technology (>120mL / h) is significantly higher than that of the conventional constant voltage technology (<22mL / h). Under the condition of a high current of 2A, the power consumption of the pulse dynamic electrolysis technology is reduced by about 4% compared with the conventional constant voltage technology. The present invention provides a new technical path for efficient and energy-saving PEMWE high-current hydrogen production based on renewable energy.

[0018] The reaction characteristics of large-area electrolyzers are significantly different from those of small-area electrolyzers. Compared with electrolyzers with smaller active areas, the influence of bubble dynamics under conditions of larger electrode areas and high currents cannot be ignored. The operating conditions of the present invention are large active areas (25 cm 2 ) and high current (2A), and operates in a low voltage range (<1.7V) where no polarization reaction occurs. Due to the relaxation effect caused by the pulse intermittent voltage, the generation dynamics of microscopic bubbles on the electrode surface are reduced, and the bubble release efficiency is significantly improved, thereby achieving a low-energy hydrogen production effect. The present invention is an innovative solution designed for the specific challenges of operating an electrolyzer with a large active area. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 It is a bubble release scheme for conventional constant voltage electrolysis and pulse dynamic electrolysis technology in the typical reaction stage of PEMWE high current hydrogen production;

[0020] Figure 2It is a polarization curve used to determine the equilibrium voltage, onset voltage, and polarization voltage, where the electrolyte flow rate is 63.2 mL / min and the scan rate is 10 mV / s;

[0021] Figure 3 It is a schematic diagram of hydrogen production current of PEMWE under conventional constant voltage and pulse dynamic voltage, where the experimental conditions are pulse frequency of 0.1 Hz and pulse duty cycle of 50%;

[0022] Figure 4 Schematic diagram of hydrogen production rate of PEMWE under different constant voltage and pulse dynamic voltage, where the experimental conditions are pulse frequency of 0.1 Hz and pulse duty cycle of 50%;

[0023] Figure 5 This is a schematic diagram of the hydrogen production current of PEMWE under conventional constant voltage and different pulse frequencies, where the experimental conditions are pulse voltage of 1.6V and pulse duty cycle of 50%;

[0024] Figure 6 This is a schematic diagram of the hydrogen production rate of PEMWE under conventional constant voltage and different pulse frequencies, where the experimental conditions are pulse voltage of 1.6V and pulse duty cycle of 50%;

[0025] Figure 7 This is a schematic diagram of the hydrogen production current of PEMWE under conventional constant voltage and different pulse duty ratios, where the experimental conditions are pulse voltage 1.6V and pulse frequency 0.1Hz;

[0026] Figure 8 This is a schematic diagram of the stable current of PEMWE under conventional constant voltage and different pulse duty ratios, where the experimental conditions are pulse voltage 1.6V and pulse frequency 0.1Hz;

[0027] Fig. 9 This is a schematic diagram of the hydrogen production rate of PEMWE under conventional constant voltage and different pulse duty ratios, where the experimental conditions are pulse voltage 1.6V and pulse frequency 0.1Hz;

[0028] Fig.10 It is a schematic diagram comparing the voltage response curves of constant current and pulse current under different large currents;

[0029] Fig.11 This is a schematic diagram of the power consumption of the PEMWE high-current hydrogen production system under conventional constant voltage and pulse dynamic electrolysis technology. DETAILED DESCRIPTION

[0030] The technical solution of the present invention will be clearly and completely described below in conjunction with the drawings and embodiments. Obviously, the described embodiments are only part of the embodiments of the invention, rather than all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

[0031] The electrochemical workstation (Shanghai Chenhua-CHI660E) was used to apply pulse voltage and record the response current under different pulse parameters, and the water electrolysis (PEMWE) hydrogen production experiment was carried out using PEM. Among them, the membrane electrode (MEA) of PEMWE is composed of Pt / C+Nafion 117 membrane+IrO2 catalyst. During the pulse dynamic electrolysis of water to produce hydrogen experiment, the peristaltic pump pumped the electrolyte deionized water into the anode chamber of the PEM cell at a flow rate of 63.2mL / min. The experiment was a full water splitting test carried out at room temperature of 25°C. Among them, the working electrode is connected to the anode side, the counter electrode and the reference electrode are connected to the cathode side, and the applied pulse voltage range is 1.4~1.6V.

[0032] The constant voltage and pulse dynamic electrolysis performance of PEMWE were studied by linear sweep voltammetry and multi-potential step pulse control. The test voltage range of linear sweep voltammetry is 1.2-1.8V, and the scan rate is 10mV / s. The product H2 was collected by the drainage gas collection method and the measurement was repeated three times. Among them, the running time of the PEMWE hydrogen production experiment under constant voltage conditions is 300s. In order to ensure that the actual working time of the pulse voltage is the same as that of the constant voltage, the pulse dynamic electrolysis technology normalizes the actual working time (that is, excluding the pulse interval time) and appropriately extends the total running time according to the duty cycle. For example, under the pulse electrolysis conditions of 50% duty cycle, the running time is twice that under the constant voltage conditions, but the actual working time is the same as that under the constant voltage conditions.

[0033] In the typical reaction stages (equilibrium voltage, starting voltage and polarization voltage) of PEMWE high current hydrogen production, the bubble release technology scheme of conventional constant voltage electrolysis and pulse dynamic electrolysis technology, such as Figure 1 shown.

[0034] In the equilibrium voltage reaction stage, the PEMWE hydrogen production reaction has just started to activate, the electrode surface maintains a low current, and local micro-bubble groups are easily formed on the membrane electrode surface, which are retained and difficult to discharge. Under the pulse dynamic electrolysis technology, the higher average hydrogen production current of the equilibrium voltage is combined with the pulse voltage intermittent period, and the bubble generation rate during the intermittent period is significantly reduced, providing sufficient time for the generated bubbles to be released from the electrode surface, thereby reducing the accumulation of micro-bubble groups.

[0035] In the initial voltage reaction stage, the current on the membrane electrode surface gradually increases, the bubble generation rate accelerates, a continuous bubble covering layer is formed on the membrane electrode surface, and the bubble release frequency decreases. The shielding effect of the bubbles hinders the mass transfer of the reactants, resulting in local concentration polarization, reducing the catalytic activity of the electrode surface, and affecting the continuity and stability of the electrolysis reaction. However, in the pulse dynamic electrolysis technology in the initial voltage stage, due to the relaxation effect generated by the periodic provision of the pulse intermittent state, the growth momentum of microscopic bubbles on the membrane electrode surface is reduced, thereby promoting the desorption of bubbles and the replenishment of reactants. This relaxation effect can significantly reduce the bubble accumulation phenomenon in the initial voltage stage, thereby maintaining a high PEMWE hydrogen production efficiency.

[0036] During the polarization voltage reaction stage, the catalytic activity of the membrane electrode is high, bubbles are generated in large quantities and the release rate is improved. It is worth noting that a thick and dense bubble covering layer is formed on the surface of the membrane electrode, which aggravates the local concentration polarization and causes a sharp drop in the mass transfer efficiency of the reactants. Under the high current conditions of the polarization voltage, the relaxation effect of the pulse is weakened. Although the bubble generation rate is accelerated in this stage, the pulse dynamic electrolysis technology still provides a short relaxation state when too many bubbles are generated, promotes the discharge of some bubbles, avoids serious bubble accumulation on the electrode surface, and thus maintains a high membrane electrode utilization rate.

[0037] Example 1

[0038] A method for improving the bubble release efficiency on the electrode surface in high-current water electrolysis to produce hydrogen, comprising the following steps:

[0039] Step 1: E on Set to a certain equilibrium voltage, starting voltage and polarization voltage (E on =1.4~1.6V), E off Set to the open circuit voltage state of PEMWE hydrogen production (E off =0V), t on and t off Both are set to 5s.

[0040] Step 2: Apply the above pulse electrolysis method to PEMWE high current hydrogen production under equilibrium voltage, starting voltage and polarization voltage.

[0041] Compared with the constant voltage, the hydrogen production current of PEMWE under different pulse dynamic voltages is shown in Figure 3 shown.

[0042] Compared with the constant voltage, the hydrogen production rate of PEMWE under different pulse dynamic voltages is as follows: Figure 4 shown.

[0043] Example 2

[0044] A method for improving the bubble release efficiency on the electrode surface in high-current water electrolysis to produce hydrogen, comprising the following steps:

[0045] Step 1: Take the polarization voltage of 1.6V, which can better reflect the actual performance of PEMWE high current hydrogen production, and set the pulse duty cycle to 50% (t on =t off ), by adjusting the low-frequency operating conditions (0.05~0.5Hz) to adapt to the volatility of renewable energy.

[0046] Step 2: Apply the above pulse electrolysis method to PEMWE high current hydrogen production with different pulse frequencies, and measure the response current and hydrogen production rate under polarization voltage.

[0047] The current of PEMWE high current hydrogen production with different pulse frequencies under pulse dynamic electrolysis technology is as follows Figure 5 shown.

[0048] The hydrogen production rate of PEMWE with different pulse frequencies under pulse dynamic electrolysis technology is as follows Figure 6 shown.

[0049] Example 3

[0050] A method for improving the bubble release efficiency on the electrode surface in high-current water electrolysis to produce hydrogen, comprising the following steps:

[0051] Step 1: Under the preferred pulse parameters of 1.6V and 0.1Hz, different pulse duty ratios were set to increase from 10% to 90%.

[0052] Step 2: Apply the above pulse electrolysis method to PEMWE high current hydrogen production with different pulse duty ratios, and measure the PEMWE hydrogen production current and stable current under polarization voltage.

[0053] The high current hydrogen production current and stable current of PEMWE with different pulse duty ratios under pulse dynamic electrolysis technology are shown in Figure 2. Figure 7 and Figure 8 shown.

[0054] Example 4

[0055] A method for improving the bubble release efficiency on the electrode surface in high-current water electrolysis to produce hydrogen, comprising the following steps:

[0056] Step 1: Under the preferred pulse parameters of 1.6V and 0.1Hz, different pulse duty ratios were set to increase from 10% to 90%.

[0057] Step 2: Apply the above pulse electrolysis method to the PEMWE hydrogen production rate under polarization voltage with different pulse duty ratios and high current hydrogen production.

[0058] The hydrogen production rate of PEMWE with different pulse duty ratios under pulse dynamic electrolysis technology is as follows Fig. 9 shown.

[0059] Example 5

[0060] A method for improving the bubble release efficiency on the electrode surface in high-current water electrolysis to produce hydrogen, comprising the following steps:

[0061] Step 1: Apply a pulse current of 0.5 to 2 A under the conditions of a preferred pulse frequency of 0.1 Hz and a duty cycle of 10%.

[0062] Step 2: Apply the above pulse electrolysis method to the PEMWE electrolyzer at different high currents, and measure the voltage response of constant current and pulse current.

[0063] The voltage response curve of pulse current under constant current and pulse dynamic electrolysis technology is as follows Fig.10 shown.

[0064] Example 6

[0065] A method for improving the bubble release efficiency on the electrode surface in high-current water electrolysis to produce hydrogen, comprising the following steps:

[0066] Step 1: Apply a pulse current of 2A at a preferred pulse frequency of 0.1 Hz and a duty cycle of 10%.

[0067] Step 2: Apply the above pulse electrolysis method to the PEMWE electrolyzer, and compare the hydrogen production energy consumption of conventional constant voltage and pulse dynamic electrolysis technology under 2A high current conditions.

[0068] Under conventional constant voltage and pulse dynamic electrolysis technology, the power consumption of PEMWE high current hydrogen production system is as follows: Fig.11 shown.

[0069] 1. Gain effect of pulse voltage

[0070] In order to explore the influence of pulse dynamic electrolysis technology on the typical reaction stages of PEMWE high-current hydrogen production, polarization curve tests were carried out under electrolyte flow rates with good mass transfer conditions to determine the equilibrium voltage, starting voltage and polarization voltage of PEMWE under high-current hydrogen production conditions, such as Figure 2 As shown. It can be seen that the three typical operating voltages of PEMWE high current hydrogen production at different reaction stages can be determined as equilibrium voltage 1.4V, starting voltage 1.5V and polarization voltage 1.6V respectively.

[0071] Compared with conventional constant voltage, the characteristic parameters of pulse dynamic electrolysis technology include pulse voltage (E on ), pulse intermittent voltage (E off ), pulse time (t on) and pulse interval time (t off ). In the present invention, E on Set to the equilibrium voltage, starting voltage and polarization voltage (E on =1.4~1.6V), E off Set to the open circuit voltage state of PEMWE hydrogen production (E off =0V). At the same time, there is no additional electrochemical reaction at this voltage, which is conducive to the regulation of pulse voltage. on and t off The PEMWE response current of conventional constant voltage and pulse dynamic electrolysis technology is as follows Figure 3 As shown. It can be seen that under conventional constant voltage, the hydrogen production current of PEMWE with equilibrium voltage and starting voltage is mainly distributed around 0A. However, under pulse dynamic electrolysis technology, the hydrogen production current of PEMWE with equilibrium voltage and starting voltage is distributed between 0 and 2A, and the average hydrogen production current is about 0.5A, which is much higher than the hydrogen production current of equilibrium voltage and starting voltage under conventional constant voltage. The same advantage is also reflected in the hydrogen production current of PEMWE with polarization voltage. Compared with hydrogen production with polarization voltage PEMWE of conventional constant voltage technology, pulse dynamic electrolysis can increase the average hydrogen production current by about 73%. This may be because the pulse dynamic electrolysis technology regularly and periodically reduces the polarization effect and enhances the reaction interface renewal rate, so that the electrode surface maintains good activity.

[0072] Correspondingly, the influence of pulse dynamic electrolysis technology on the typical reaction stage of PEMWE high current hydrogen production is also reflected in the hydrogen production rate. Under conventional constant voltage and pulse dynamic electrolysis technology, the influence of equilibrium voltage, starting voltage and polarization voltage on hydrogen production rate, such as Figure 4 As shown. It can be seen that under the pulse dynamic electrolysis technology, the high current hydrogen production rate of PEMWE at the equilibrium voltage, starting voltage and polarization voltage is much higher than that of the conventional constant voltage technology. Specifically, in the reaction stage of equilibrium voltage 1.4V, the pulse dynamic electrolysis technology shows the greatest advantage, which can greatly increase the hydrogen production rate from 2.5mL / h of the conventional constant voltage technology to 123.3mL / h, achieving a significant increase in hydrogen production rate.

[0073] 2. Pulse frequency gain effect

[0074] The pulse frequency refers to the frequency at which the current circulates in the pulse dynamic operation, reflecting the response performance of the PEM cell under intermittent renewable energy operation. Based on this, the polarization voltage of 1.6V is selected to better reflect the actual performance of PEMWE high current hydrogen production, and the pulse duty cycle is fixed to 50% (t on =t off), by adjusting the low-frequency working condition (0.05-0.5Hz) to adapt to the volatility of renewable energy, the influence of different pulse frequencies on the high-current hydrogen production performance of PEMWE under polarization voltage was studied. The PEMWE response current curves of conventional constant voltage and different pulse frequencies, such as Figure 5 As shown. It can be seen that as the pulse frequency increases from 0.05Hz to 0.5Hz and the pulse period decreases from 20s to 2s, the peak response current of PEMWE shows an overall downward trend. Among them, at pulse frequencies of 0.1Hz and 0.5Hz, the stabilized response current increased by 10% and 17% respectively compared with the constant voltage condition. However, due to the higher pulse frequency of 0.5Hz, the hydrogen production current is mainly dominated by the double layer charging current, resulting in a hydrogen production rate much lower than the constant voltage condition. It shows that the lower pulse frequency of 0.1Hz can improve the effective electrolysis process, weaken the polarization effect, and maintain a higher electrolysis current.

[0075] The consistent pulse dynamic electrolysis effect is also reflected in the hydrogen production rate, such as Figure 6 As shown. It can be seen that the hydrogen production rate at lower pulse frequencies of 0.05Hz and 0.1Hz is improved compared with the constant voltage condition. Specifically, the hydrogen production rates at pulse frequencies of 0.05Hz and 0.1Hz are increased by about 27% and 30% respectively compared with the constant voltage condition. This can be attributed to the fact that at lower pulse frequencies, the pulse dynamic electrolysis technology effectively improves the adsorption microenvironment of the intermediates and alleviates the polarization phenomenon. In particular, when H2 is generated on the electrode surface, the coverage of the active area by bubbles is partially eliminated during the periodic pulse intervals, improving the mass transfer conditions on the electrode surface. This effect is more significant at lower frequencies of 0.05Hz and 0.1Hz. However, at higher pulse frequencies, due to the short electrochemical reaction time on the PEMWE electrode, the frequent charging and discharging of the double layer increases the contribution of the non-Faraday process to the total current, thereby reducing the overall hydrogen production rate.

[0076] 3. Gain effect of pulse duty cycle

[0077] Pulse duty cycle usually refers to the duration of current in a unit pulse cycle. In the process of PEMWE high-current hydrogen production, the regulation of pulse duty cycle directly affects the response characteristics of the system under unstable voltage step supply and the dynamic behavior of the electrode. To this end, under the optimal pulse parameters of 1.6V and 0.1Hz, the effect of different pulse duty cycles on the high-current hydrogen production performance of PEMWE was investigated. The PEMWE response current curves of conventional constant voltage and different pulse duty cycles (10% to 90%) are shown in Figure 2. Figure 7As shown. It can be seen that as the pulse duty cycle increases from 10% to 90%, the PEMWE hydrogen production current shows a downward trend. It is worth noting that when the pulse duty cycle is greater than 50%, the stabilized PEMWE hydrogen production current tends to be lower than the constant voltage condition, and the stable current with a duty cycle of 90% is about 10% lower than that of constant voltage electrolysis. This may be because at higher duty cycles of 60% to 90%, as the duty cycle and PEMWE electrochemical reaction time increase, bubbles gradually accumulate on the electrode surface, resulting in limited mass transfer of reactants, further exacerbating the local overpotential of the electrode and the concentration polarization of the interface, making gas diffusion and bubble management limiting factors.

[0078] Furthermore, from the stable current under different pulse duty ratios ( Figure 8 ) It can be seen that the hydrogen production after the pulse duty cycle of 10% and 20% is much higher than the constant voltage condition, which increases the PEMWE hydrogen production current by about 350% and 79% respectively. This is attributed to the long pulse interval time of each cycle under the low pulse duty cycle of 10% and 20%, and the periodic pulse cycle effectively promotes the release of bubbles on the electrode surface, reduces the coverage of bubbles on the electrode surface, and improves electrode polarization and concentration polarization. This shows that short high current pulses are more conducive to stimulating the kinetic process of electrochemical reactions.

[0079] The corresponding advantages are also reflected in the hydrogen production rate, such as Fig. 9 As shown, when the pulse duty cycle is between 10% and 50%, the hydrogen production rate of the pulse dynamic electrolysis technology is significantly higher than that under conventional constant voltage conditions, and can be increased by up to about 89%.

[0080] 4. Hydrogen production performance of high current PEMWE using pulse dynamic electrolysis technology

[0081] Based on the bubble management and improved polarization effect of pulse dynamic electrolysis technology for PEMWE high current hydrogen production, the present invention evaluates the performance of pulse high current PEMWE hydrogen production. Under the preferred pulse parameters (frequency 0.1Hz and duty cycle 10%), the system was tested for voltage response under constant current and pulse current conditions. Fig.10 As shown. It can be seen that under different currents, the pulse current significantly reduces the average voltage of the PEMWE cell compared to the constant current condition. Specifically, the intermittent time of the pulse current releases the bubbles on the electrode surface, thereby reducing the polarization effect and slowing down the rise of local overpotential. The drop in voltage shows that the pulse current can reduce the polarization of the electrode and improve the efficiency of PEMWE high-current hydrogen production. At the same time, the intermittent time period of the pulse current enables the pulse current application period to more efficiently participate in the electrochemical reaction and increase the instantaneous rate of hydrogen production. In order to further evaluate the energy consumption of pulse dynamic electrolysis technology compared to constant energy supply, Fig.11The power consumption of the PEMWE high-current hydrogen production system is shown. It is worth noting that under the current condition of 2A, the power consumption of pulse dynamic electrolysis is reduced by about 4% compared with the constant voltage technology, indicating that the pulse dynamic electrolysis technology can more efficiently use electrical energy for hydrogen production. This may be because the pulse dynamic electrolysis technology can effectively alleviate the bubble accumulation and polarization effect under high current, thereby improving energy utilization efficiency, showing the potential for low-energy production of hydrogen.

[0082] In addition, it should be understood that although the present specification is described according to implementation modes, not every implementation mode contains only one independent technical solution. This description of the specification is only for the sake of clarity. Those skilled in the art should regard the specification as a whole. The technical solutions in each embodiment may also be appropriately combined to form other implementation modes that can be understood by those skilled in the art.

Claims

1. A method for improving the bubble release efficiency on the electrode surface in high current water electrolysis to produce hydrogen, characterized in that: The following steps are involved: Step 1: Apply pulse voltage to the proton exchange membrane electrolyzer to produce hydrogen by water electrolysis. The membrane electrode area of ​​the proton exchange membrane electrolyzer is 25 cm 2 , the applied pulse voltage range is 1.4-1.6V; Step 2: Deionized water of the electrolyte is transported to the anode chamber of the proton exchange membrane electrolyzer, thereby initiating an oxidation reaction to produce hydrogen.

2. The method according to claim 1, characterized in that: In step 1, the pulse current applied is 0.5-2A.

3. The method according to claim 1, characterized in that: In step 1, the pulse frequency is 0.05Hz-0.5Hz.

4. The method according to claim 3, characterized in that: In step 1, the pulse frequency is 0.05Hz-0.1Hz.

5. The method according to claim 1, characterized in that: In step 1, the pulse duty cycle is 10%-90%.

6. The method according to claim 5, characterized in that: In step 1, the pulse duty cycle is 10%-20%.

7. The method according to claim 1, characterized in that: In step 1, the pulse intermittent voltage is set to the open circuit voltage state of PEMWE hydrogen production.

8. The method according to claim 7, characterized in that: In step 1, the pulse intermittent voltage is set to 0V.

9. The method according to claim 1, characterized in that: In step 1, the proton exchange membrane electrolyzer includes an electrolyzer and a membrane electrode, wherein the membrane electrode is composed of Pt / C+Nafion 117 membrane+IrO2 catalyst.

10. The method according to claim 1, characterized in that: In step 2, the delivery rate of deionized water as the electrolyte is 63.2 mL / min.

Images