Catalyst for hydrogen production device of proton exchange membrane electrolysis water and preparation method and application thereof

Abstract

The application discloses a catalyst for a hydrogen production device for electrolysis of water by a proton exchange membrane and a preparation method and application thereof, the catalyst is manganese ruthenium metal oxide nanoparticles loaded on a conductive network of nitrogen-doped carbon nanotubes grown on a carbon cloth, and the mass ratio of manganese to ruthenium is 5-9:1-5; the nitrogen-doped carbon nanotubes have excellent conductive performance, the fine reticular structure is beneficial to more attachment of active substances, and the nitrogen-doped carbon nanotubes also have a high specific surface area and a stable three-dimensional structure, so that a good precursor is provided for subsequent hydrothermal growth of manganese ruthenium metal oxide, and the agglomeration of nanoparticles is avoided; PECVD makes the manganese ruthenium metal oxide nanoparticles more dispersed and uniform, further improves the specific surface area, exposes more active sites, and improves the catalytic activity; the interaction has greater conductive electron performance, and the basic skeleton of the manganese ruthenium metal oxide can also provide conditions for mass transfer of electrolysis of water, so that the electrode catalyst provides a larger channel for electron transfer.

Description

Technical Field

[0001] This invention belongs to the field of water electrolysis catalyst technology, and in particular relates to a nitrogen-doped carbon nanotube-based catalyst for a proton exchange membrane water electrolysis hydrogen production device, its preparation method, and its application as a catalyst for the oxygen evolution reaction in proton exchange membrane water electrolysis. Background Technology

[0002] With the continuous development of society, economy, science, and technology, human dependence on electricity is increasing daily. 70% of this electricity comes from the combustion of traditional fossil fuels, leading to the depletion of these fuels and severe environmental pollution. In response, many efforts have been made to utilize natural renewable energy sources (solar and wind power) to achieve pollution-free, zero-emission, and sustainable power generation. However, the intermittency, volatility, and seasonality of these renewable energy sources reduce the safety and stability of the power system, resulting in significant energy waste such as "curtailment" of wind and solar power. Electrochemical energy storage and conversion systems, such as water electrolysis for hydrogen production, metal-air batteries, and lithium-ion batteries, offer advantages such as high efficiency, controllability, stability, fast response, safety, and ease of integration. These systems can ensure the stability of the power grid and reduce secondary waste in power generation.

[0003] Electrolysis of water to produce hydrogen is an energy storage technology that uses electricity to split water into hydrogen (H2) and oxygen (O2), storing the electrical energy in the hydrogen. Hydrogen is one of the cleanest energy carriers with a high specific energy, and its combustion produces water, thus overcoming environmental pollution problems. Combined with hydrogen-oxygen fuel cell technology, its chemical energy can be converted back into electrical energy and fed into the power grid. Depending on the electrolyte, water electrolysis can be classified into alkaline water electrolysis (AWE), anion exchange membrane water electrolysis (AEM), proton exchange membrane water electrolysis (PEM), and solid metal oxide water electrolysis (SOE). Among these, the proton exchange membrane electrolyzer (PEMWE) using PEM has several advantages, including lower ohmic resistance, higher current density, purer hydrogen production, lower energy consumption, faster system response, and better compatibility with sustainable energy resources. Coupled with renewable energy power generation technologies, it can improve the stability of renewable energy power generation. Therefore, proton exchange membrane water electrolysis devices have attracted widespread attention and extensive research as energy storage equipment.

[0004] Here, catalysts face severe degradation in acidic electrolytes, especially oxygen evolution reaction (OER) catalysts subjected to strong oxidizing environments at high operating voltages. This is because OER is a four-electron-proton coupled reaction, requiring higher energy (higher overpotentials), making the OER overpotential much higher than the theoretical decomposition voltage of water (1.23V). Ruthenium oxide (RuO2) and iridium oxide (lrO2) are benchmark OER catalysts, exhibiting high activity under acidic conditions, but they are scarce and expensive (Ir 175,000 USD kg). -1 Ru 16,400 USD kg -1 The limited availability of these precious metal catalysts restricts their commercial application; furthermore, these catalysts exhibit poor stability and do not meet long-term stability requirements. Therefore, it is essential to design low-cost, stable, and efficient catalysts.

[0005] Current research in this field focuses on minimizing the use of precious metals, or doping precious metals with abundant metals or second-order transition metals to improve stability while maintaining a comparable level of catalytic performance. Ruthenium oxide, due to its role in the reaction intermediate (i.e., O... 2- OH - and OOH - Ruthenium oxide exhibits high AOER activity due to its favorable binding energy. Ruthenium oxide possesses different crystal structures, such as rutile oxide, pyrochlore oxide, and perovskite oxide. Adjusting the adsorption strength of intermediates affects AOER performance, with rutile-type ruthenium oxide being the most active catalyst in AOER. However, its stability exhibits the opposite phenomenon. Therefore, effective strategies are needed to improve the stability of ruthenium oxide without affecting its catalytic activity. Numerous studies, including experimental and theoretical results, have shown that manganese, a transition metal abundant on Earth, can be doped into RuO2. This alters the charge redistribution between Ruthenium and the transition metal, thereby changing the electronic structure, forming Mn-O-Ru ligands, optimizing the binding energy of intermediates, lowering the reaction barrier, and improving the catalytic activity of OER. This approach achieves the goal of maintaining activity while reducing the amount of precious metal used.

[0006] However, the active materials on the catalyst surface are easily converted into unstable metal oxides under acidic conditions, and are prone to decomposition and structural collapse, resulting in rapid loss of activity and a lack of long-term stability. Therefore, it is particularly important to find a simple method to immobilize the active materials on the catalyst surface on a support and slow down their detachment time, so as to maintain high efficiency while improving long-term stability. Summary of the Invention

[0007] One of the technical problems to be solved by the present invention is to provide a manganese ruthenium metal oxide catalyst supported on nitrogen-doped carbon nanotubes with high specific surface area, many active sites, excellent performance, low cost and long-term stability.

[0008] The technical solution adopted by this catalyst to solve the above-mentioned technical problems is as follows: a catalyst for a proton exchange membrane electrolysis water production device, the structure of which uses nitrogen-doped carbon nanotubes grown on carbon cloth as a conductive network, and manganese and ruthenium metal oxide nanoparticles are uniformly loaded on the conductive network after hydrothermal reaction and radio frequency enhanced plasma chemical vapor deposition in an oxygen atmosphere; the molar ratio of manganese to ruthenium is 5-9:1-5.

[0009] Another technical problem to be solved by the present invention is to provide a method for preparing the above-mentioned catalyst for a proton exchange membrane water electrolysis hydrogen production device, specifically comprising the following steps:

[0010] (i) Growth of nitrogen-doped carbon nanotubes on carbon cloth;

[0011] (ii) Manganese ruthenium metal oxide nanoparticles loaded with hydrothermal heat;

[0012] (iii) Radio frequency enhanced plasma chemical vapor deposition was performed in an oxygen atmosphere to obtain nitrogen-doped carbon nanotube-supported manganese ruthenium metal oxide nanoparticle catalysts grown on carbon cloth.

[0013] Compared with existing technologies, the advantages of this catalyst and its preparation method are as follows:

[0014] (1) Carbon cloth with nitrogen-doped carbon nanotubes is an excellent conductive substrate. Carbon cloth (CC) is considered a very promising catalyst support due to its large specific surface area, excellent flexibility, and abundant active sites. Growing electrode materials on CC can effectively prevent the aggregation of active materials, make full use of catalytic sites, improve catalyst stability, and the nano-three-dimensional structure is conducive to electron conduction. At the same time, its extremely high specific surface area can provide abundant active sites for the reaction. Nitrogen-doped carbon nanotubes themselves have excellent conductivity. The fine network structure of nitrogen-doped carbon nanotubes is conducive to attaching more electrochemical active materials to the surface of carbon nanotubes, making them uniform. Nitrogen-doped carbon nanotubes also have a high specific surface area and a stable three-dimensional structure. Moreover, their special three-dimensional structure provides a good precursor for the subsequent hydrothermal growth of manganese ruthenium metal oxide nanoparticles. The metal oxide loaded on the surface of carbon cloth with nitrogen-doped carbon nanotubes can achieve uniform loading while maintaining the nanoscale structure. Therefore, uniformly loading manganese ruthenium metal oxide on nitrogen-doped carbon nanotubes can obtain OER catalysts with better performance.

[0015] (2) Manganese and ruthenium metal oxides grown by hydrothermal method are uniformly covered on nitrogen-doped carbon nanotubes in the form of nanoparticles. The charge redistribution between manganese and ruthenium changes the electronic structure, forming a Mn-O-Ru structure, which optimizes the binding energy of the intermediate, lowers the reaction barrier, and improves the catalytic activity of OER. This achieves the goal of reducing the amount of precious metals used while maintaining its activity, thus saving the preparation cost.

[0016] (3) Treatment of nitrogen-doped carbon nanotube-supported manganese ruthenium metal oxide nanoparticles by radio frequency enhanced plasma chemical vapor deposition can significantly improve catalytic activity. Treatment in an oxygen atmosphere can remove organic impurities, increase oxygen vacancies, improve the oxidizing power of the metal, and enhance long-term stability. This process makes the manganese ruthenium metal oxide nanoparticles more uniformly dispersed, avoids nanoparticle aggregation, further increases their specific surface area, thereby exposing more active sites and improving their catalytic activity. Furthermore, it enhances the electron conduction performance of the interaction between the catalyst and the support. The basic framework of manganese ruthenium metal oxides also provides conditions for mass transfer in water electrolysis, thus providing a larger channel for electron transfer as an electrode catalyst.

[0017] Preferably, in step (ii), a certain amount of potassium permanganate and ruthenium trichloride are weighed, dissolved in deionized water, and stirred thoroughly. A quantitative amount of HCl is added dropwise while stirring, and the solution is stirred until it is evenly mixed. The solution is then poured into the polytetrafluoroethylene liner of an oven. The carbon cloth with nitrogen-doped carbon nanotubes prepared in step (i) is then placed in the solution. After the oven is closed, a hydrothermal reaction is carried out. The temperature is raised to 120°C and maintained for 12 hours. The solution is then naturally cooled to room temperature, removed, and washed three times with deionized water and ethanol before drying. The molar ratio of potassium permanganate to ruthenium trichloride is 5–9:1–5.

[0018] Preferably, the molar ratio of potassium permanganate to ruthenium trichloride is 7:3.

[0019] Preferably, in step (iii), the gas pressure of the radio frequency enhanced plasma chemical vapor deposition treatment is 20 Pa, the radio frequency power is 40 W to 130 W, the time is 5 min to 20 min, and the temperature is 200 °C to 350 °C. This achieves the effect of increasing oxygen vacancies, improving the crystallinity of manganese ruthenium metal oxide, and making the nanoparticles finer and more uniformly dispersed, firmly fixing them on the support, increasing the specific surface area of ​​the catalyst, exposing more active sites, and thus improving the catalytic activity and stability of the catalyst.

[0020] Optimal for radio frequency (RF) enhanced plasma chemical vapor deposition (RFCVD) is a RF power of 100W, a temperature of 250℃, and a time of 5 minutes. The RF power and time for RF plasma etching should not be too high. Excessive RF power will result in overly strong plasma bombardment, leading to structural breakage and reduced cycle stability; excessive time will cause damage to the nanotubes. Conversely, insufficient RF power will result in inadequate bombardment and poor results.

[0021] Another technical problem to be solved by the present invention is to provide an application of the above-mentioned catalyst as a catalyst for the oxygen evolution reaction in proton exchange membrane electrolysis of water. Attached Figure Description

[0022] Figure 1 P(O2) prepared in Example 1 T不同温度 -Mn 0.35 Ru 0.15 O x Linear sweep voltammetry (LSV) plot of the oxygen evolution reaction (OER) of @NCNTs / CC.

[0023] Figure 2 P(O2) prepared in Example 2 t不同时间 -Mn 0.35 Ru 0.15 O x Linear sweep voltammetry (LSV) plot of the oxygen evolution reaction (OER) of @NCNTs / CC.

[0024] Figure 3 P(O2) prepared in Example 3 w不同功率 -Mn 0.35 Ru 0.15 O x Linear sweep voltammetry (LSV) plot of the oxygen evolution reaction (OER) of @NCNTs / CC.

[0025] Figure 4 To explore the microstructure (scale bar 500 nm) of the catalyst prepared under the optimal conditions of radio frequency enhanced plasma chemical vapor deposition in an oxygen atmosphere.

[0026] Figure 5 Microscopic morphology (scale bar 500 nm) of catalyst semi-finished product prepared under optimal conditions without radio frequency enhanced plasma chemical vapor deposition treatment.

[0027] Figure 6Linear sweep voltammetry (LSV) plots of oxygen evolution reaction (OER) for catalysts prepared under optimal conditions of radio frequency enhanced plasma chemical vapor deposition treatment in oxygen atmosphere, as well as for commercial RuO2 catalysts, in Comparative Examples 1 and 2.

[0028] Figure 7 Stability test results for catalysts prepared under optimal conditions of radio frequency enhanced plasma chemical vapor deposition (RF-Enhanced Plasma Chemical Vapor Deposition) in comparative examples 1 and 2, and catalyst semi-finished products without RF-Enhanced Plasma Chemical Vapor Deposition (RF-Enhanced Plasma Chemical Vapor Deposition). Detailed Implementation

[0029] The following description, in conjunction with the accompanying drawings, illustrates exemplary embodiments of the present invention, including various details to aid understanding. These details should be considered merely exemplary. Therefore, those skilled in the art will recognize that various changes and modifications can be made to the embodiments described herein without departing from the scope and spirit of the invention. Similarly, for clarity and brevity, descriptions of well-known functions and structures are omitted in the following description.

[0030] The catalyst for the proton exchange membrane water electrolysis hydrogen production device of the present invention is a self-supported nitrogen-doped carbon nanotube-supported manganese-ruthenium metal oxide nanoparticle. Its structural unit uses nitrogen-doped carbon nanotubes grown on carbon cloth as a conductive network, with the manganese-ruthenium metal oxide nanoparticles loaded on the conductive network. The molar ratio of manganese to ruthenium is 5–9:1–5. Among these, a manganese-ruthenium molar ratio of 7:3 is optimal in terms of both performance and price, and this can be verified through a limited number of experiments. The following examples and comparative examples were conducted under these conditions.

[0031] The specific preparation method includes the following steps:

[0032] (i) Growth of nitrogen-doped carbon nanotubes on carbon cloth to provide conductivity;

[0033] (ii) Hydrothermal growth of manganese-ruthenium metal oxide nanoparticles;

[0034] (III) Surface modification and carbonization were carried out by radio frequency enhanced plasma chemical vapor deposition (PECVD) in an oxygen atmosphere to obtain a nitrogen-doped carbon nanotube-supported manganese ruthenium metal oxide nanoparticle electrode catalyst grown on a self-supporting carbon cloth.

[0035] To explore different conditions for oxygen plasma PECVD treatment, obtain the optimal conditions, and evaluate its application value as a catalyst for oxygen evolution in proton exchange membrane water electrolysis by testing its corresponding catalytic performance.

[0036] Example 1:

[0037] The specific method for preparing nitrogen-doped carbon nanotube-supported manganese ruthenium metal oxide nanoparticle catalysts grown on carbon cloth at different temperatures during oxygen plasma PECVD treatment is as follows:

[0038] (1) Growth of nitrogen-doped carbon nanotubes on carbon cloth: Nitrogen-doped carbon nanotubes (NCNTs) were prepared using cobalt nitrate hexahydrate, zinc nitrate hexahydrate, and dimethylimidazole as raw materials. 0.385 g of Co(NO3)2·6H2O and 0.197 g of Zn(NO3)2·6H2O were dissolved in 40 ml of deionized water to form solution A. Then, 1.3 g of dimethylimidazole was dissolved in 40 ml of deionized water to form solution B. After stirring each solution thoroughly, solution A was poured into solution B to form a mixed solution. A 3*4 cm carbon cloth was placed in the mixed solution and allowed to stand for 4 hours to form ZnCo ZIF-CC. The cloth was then removed and repeatedly washed with deionized water and ethanol, and dried in an oven for later use. Subsequently, 3g of melamine was weighed and placed in a ceramic boat. NCNTs were suspended on both sides of the ceramic boat and placed in the center of a tube furnace. The furnace was heated to 750℃ at 5℃ / min in a N2 atmosphere and held for 2 hours. After natural cooling, nitrogen-doped carbon nanotubes were grown on the carbon cloth and labeled as NCNTs / CC.

[0039] (II) Hydrothermal Growth of Manganese Ruthenium Metal Oxide Nanoparticles: The total molar amount of potassium permanganate and ruthenium trichloride was controlled to be 0.5 mmol, and the optimal molar ratio of potassium permanganate to ruthenium trichloride was selected as 7:3. Detailed steps were as follows: 0.0553 g of potassium permanganate and 0.0311 g of ruthenium trichloride were weighed and dissolved in 32 ml of deionized water, and stirred for 15 min; then, 2 ml of HCl was added dropwise while stirring, and stirring was continued for 10 min; after uniform mixing, the mixture was poured into a 50 ml polytetrafluoroethylene (PTFE) inner liner, and the precursor NCNTs / CC was placed inside the liner, tightened, and placed in an oven for hydrothermal reaction. The temperature was raised to 120℃ and held for 12 h, then naturally cooled to room temperature. The nanoparticles were then removed, washed three times repeatedly with deionized water and ethanol, dried in an oven, and labeled as Mn. 0.35 Ru 0.15 O x @NCNTs / CC.

[0040] (III) Carbonization of manganese ruthenium metal oxide nanoparticles grown on nitrogen-doped carbon nanotubes using PECVD in an oxygen atmosphere: First, the pressure was controlled at 20 Pa and the power at 100 W for 5 min. Different temperatures (200℃-350℃) were explored, with the temperature increased to 200℃, 250℃, 300℃, and 350℃ respectively. Radio frequency processing was then initiated for 5 min, producing a pink glow. The nanoparticles were then naturally cooled to room temperature. Manganese ruthenium metal oxide nanoparticles loaded on nitrogen-doped carbon nanotubes were obtained after oxygen plasma treatment at different temperatures, labeled as P(O2)T. 不同温度 -Mn 0.35 Ru0.15 O x @NCNTs / CC.

[0041] OER (Oxygen Evolution Rate) catalytic performance evaluation:

[0042] The electrocatalytic performance of the prepared samples was tested using an electrochemical workstation (CHI760E) in a three-electrode configuration.

[0043] Preparation of working electrode for OER performance testing: Cut a 1*1cm electrode for later use.

[0044] Electrochemical performance testing: A standard three-electrode electrochemical testing system was used, with a Pt sheet electrode as the counter electrode, a saturated calomel electrode (SCE) as the reference electrode, and the working electrode prepared above. The test solution was a 0.5M H₂SO₄ solution (pH = 0). All potentials were calculated using the Nernst equation with reference to the reversible hydrogen electrode (RHE): E(RHE) = E(Hg / Hg₂Cl₂) + 0.2415 + 0.059pH. Before linear sweep voltammetry (LSV) testing, the working electrode was tested at 10 mV / s. -1 The scan rate was activated by cyclic voltammetry (CV) for 50 cycles. All electrochemical tests were performed at room temperature.

[0045] Test procedure: A certain amount of 0.5M H2SO4 was poured into the electrolytic cell, and the working electrode, reference electrode, and counter electrode were prepared. A 1*1cm catalyst was clamped with the working electrode, and then a saturated reference electrode of calomel (Hg) (SCE) and a counter electrode of Pt were placed on it. The results are as follows. Figure 1 As shown. P(O2) 250℃ -Mn 0.35 Ru 0.15 O x The @NCNTs / CC sample exhibited high OER electrocatalytic activity, requiring only a potential of 114.5 mV to drive a 10 mA cm⁻¹ electrocatalysis. -2 The current density is higher than that of the catalyst tested under the same conditions for oxygen plasma treatment at different temperatures, and its electrocatalytic activity is higher.

[0046] Example 2:

[0047] The specific method for preparing nitrogen-doped carbon nanotube-supported manganese ruthenium metal oxide nanoparticle catalysts grown on carbon cloth at different times during oxygen plasma PECVD treatment is as follows:

[0048] (1) Growth of nitrogen-doped carbon nanotubes on carbon cloth: Nitrogen-doped carbon nanotubes (NCNTs) were prepared using cobalt nitrate hexahydrate, zinc nitrate hexahydrate, and dimethylimidazole as raw materials. 0.385 g of Co(NO3)2·6H2O and 0.197 g of Zn(NO3)2·6H2O were dissolved in 40 ml of deionized water to form solution A. Then, 1.3 g of dimethylimidazole was dissolved in 40 ml of deionized water to form solution B. After stirring each solution thoroughly, solution A was poured into solution B to form a mixed solution. A 3*4 cm carbon cloth was placed in the mixed solution and allowed to stand for 4 hours to form ZnCo ZIF-CC. The cloth was then removed and repeatedly washed with deionized water and ethanol, and dried in an oven for later use. Subsequently, 3g of melamine was weighed and placed in a ceramic boat. NCNTs were suspended on both sides of the ceramic boat and placed in the center of a tube furnace. The furnace was heated to 750℃ at 5℃ / min in a N2 atmosphere, held for 2 hours, and then allowed to cool naturally to form nitrogen-doped carbon nanotubes, denoted as NCNTs / CC.

[0049] (II) Hydrothermal Growth of Manganese Ruthenium Metal Oxide Nanoparticles: The total molar amount of potassium permanganate and ruthenium trichloride was controlled to be 0.5 mmol, and the optimal molar ratio of potassium permanganate to ruthenium trichloride was selected as 7:3. Detailed steps were as follows: 0.0553 g of potassium permanganate and 0.0311 g of ruthenium trichloride were weighed and dissolved in 32 ml of deionized water, and stirred for 15 min. Then, 2 ml of HCl was added dropwise while stirring, and stirring was continued for 10 min. After uniform mixing, the solution was poured into a 50 ml polytetrafluoroethylene (PTFE) liner, and the precursor NCNTs / CC was placed inside the liner. The liner was then tightened and placed in an oven for hydrothermal reaction. The temperature was raised to 120℃ and maintained for 12 h. After natural cooling to room temperature, the nanoparticles were removed. They were washed three times with deionized water and ethanol, dried in an oven, and labeled as Mn. 0.35 Ru 0.15 O x @NCNTs / CC.

[0050] (III) Carbonization of manganese ruthenium metal oxide nanoparticles grown on nitrogen-doped carbon nanotubes using PECVD in an oxygen atmosphere: First, the pressure was controlled at 20 Pa, the power at 100 W, and the temperature at 250 °C, and different treatment times (5 min–20 min) were explored. The treatment times were controlled at 5 min, 10 min, 15 min, and 20 min, respectively, with radio frequency treatment performed for different times, producing a pink glow. The nanoparticles were then naturally cooled to room temperature. Manganese ruthenium metal oxide nanoparticles loaded on nitrogen-doped carbon nanotubes after oxygen plasma treatment for different times were obtained and labeled as P(O2). t不同时间 -Mn 0.35 Ru 0.15 O x @NCNTs / CC,

[0051] Bifunctional catalytic performance evaluation:

[0052] P(O2) was tested using an electrolytic cell. t不同时间 -Mn 0.35 Ru 0.15 O x The linear sweep voltammetry LSV curve of the OER of @NCNTs / CC is shown in the figure. Figure 2 As shown. P(O2) 5min -Mn 0.35 Ru 0.15 O x The @NCNTs / CC sample exhibited high OER electrocatalytic activity, requiring only a potential of 114.5 mV to drive a 10 mA cm⁻¹ electrocatalysis. -2 The current density was higher than that of other catalysts tested under the same conditions for oxygen plasma treatment at different times, and its electrocatalytic activity was higher.

[0053] Example 3:

[0054] The specific method for preparing nitrogen-doped carbon nanotube-supported manganese ruthenium metal oxide nanoparticle catalysts grown on carbon cloth under different power conditions during oxygen plasma PECVD treatment is as follows:

[0055] (1) Growth of nitrogen-doped carbon nanotubes on carbon cloth: Nitrogen-doped carbon nanotubes (NCNTs) were prepared using cobalt nitrate hexahydrate, zinc nitrate hexahydrate, and dimethylimidazole as raw materials. 0.385 g of Co(NO3)2·6H2O and 0.197 g of Zn(NO3)2·6H2O were dissolved in 40 ml of deionized water to form solution A. Then, 1.3 g of dimethylimidazole was dissolved in 40 ml of deionized water to form solution B. After stirring each solution thoroughly, solution A was poured into solution B to form a mixed solution. A 3*4 cm carbon cloth was placed in the mixed solution and allowed to stand for 4 hours to form ZnCo ZIF-CC. The cloth was then removed and repeatedly washed with deionized water and ethanol, and dried in an oven for later use. Subsequently, 3g of melamine was weighed and placed in a ceramic boat. NCNTs were suspended on both sides of the ceramic boat and placed in the center of a tube furnace. The furnace was heated to 750℃ at 5℃ / min in a N2 atmosphere, held for 2 hours, and then allowed to cool naturally to form nitrogen-doped carbon nanotubes, denoted as NCNTs / CC.

[0056] (II) Hydrothermal Growth of Manganese Ruthenium Metal Oxide Nanoparticles: The total molar amount of potassium permanganate and ruthenium trichloride was controlled to be 0.5 mmol, and the optimal molar ratio of potassium permanganate to ruthenium trichloride was selected as 7:3. Detailed steps were as follows: 0.0553 g of potassium permanganate and 0.0311 g of ruthenium trichloride were weighed and dissolved in 32 ml of deionized water, and stirred for 15 min; then, 2 ml of HCl was added dropwise while stirring, and stirring was continued for 10 min; after uniform mixing, the mixture was poured into a 50 ml polytetrafluoroethylene (PTFE) inner liner, and the precursor NCNTs / CC was placed inside the liner, tightened, and placed in an oven for hydrothermal reaction. The temperature was raised to 120℃ and maintained for 12 h. After natural cooling to room temperature, the nanoparticles were removed. They were washed three times with deionized water and ethanol, dried in an oven, and labeled as Mn. 0.35 Ru 0.15 O x NCNTs / CC.

[0057] (III) Carbonization of manganese ruthenium oxide nanoparticles grown on nitrogen-doped carbon nanotubes using PECVD in an oxygen atmosphere: First, the pressure was controlled at 20 Pa, the temperature at 250 °C, and the time at 5 min. Different power levels (40 W-130 W) were explored. The time was controlled at 40 W, 70 W, 100 W, and 130 W, respectively, and radio frequency processing was initiated at different power levels, producing a pink glow. The nanoparticles were then naturally cooled to room temperature. Manganese ruthenium oxide nanoparticles loaded on nitrogen-doped carbon nanotubes were obtained after oxygen plasma treatment at different power levels and labeled as P(O2). w不同功率 -Mn 0.35 Ru 0.15 O x @NCNTs / CC.

[0058] Bifunctional catalytic performance evaluation:

[0059] P(O2) was tested using an electrolytic cell. w不同功率 -Mn 0.35 Ru 0.15 O x The linear sweep voltammetry LSV curve of the OER of @NCNTs / CC is shown in the figure. Figure 3 As shown. P(O2) 100w -Mn 0.35 Ru 0.15 O x The @NCNTs / CC sample exhibited high OER electrocatalytic activity, requiring only a potential of 110.5 mV to drive a 10 mA cm⁻¹ electrocatalysis. -2 The current density is higher than that of catalysts with different powers tested under the same conditions for oxygen plasma treatment.

[0060] Note: Based on the exploration of different oxygen plasma conditions in step three, the optimal conditions are: pressure 20 Pa, power 100 W, temperature 250 °C, and time 5 min. It exhibits excellent AOER catalytic performance, requiring only a potential of 110.5 mV to drive a 10 mA cm⁻¹ plasma. -2 The current density is high, and it has a large current density. The final sample P(O2)-Mn after oxygen plasma treatment... 0.35 Ru 0.15 O x Morphology of @NCNTs / CC and Mn in sample before treatment 0.35 Ru 0.15 O x The appearance of @NCNTs / CC is as follows Figure 4 As shown, after treatment under optimal conditions, the morphology of the nanoparticles is uniformly diffused, which disperses the particles that were originally piled up in the nanotubes, increases the specific surface area, exposes more active sites, and thus further increases its catalytic activity, while also greatly improving its stability.

[0061] Comparative Example 1:

[0062] The specific method for oxygen radio frequency plasma treatment of nitrogen-doped nanotube-supported pure Mn metal oxide nanoparticle catalysts is as follows:

[0063] (1) Growth of nitrogen-doped carbon nanotubes on carbon cloth: Nitrogen-doped carbon nanotubes (NCNTs) were prepared using cobalt nitrate hexahydrate, zinc nitrate hexahydrate, and dimethylimidazole as raw materials. 0.385 g of Co(NO3)2·6H2O and 0.197 g of Zn(NO3)2·6H2O were dissolved in 40 ml of deionized water to form solution A. Then, 1.3 g of dimethylimidazole was dissolved in 40 ml of deionized water to form solution B. After stirring each solution thoroughly, solution A was poured into solution B to form a mixed solution. A 3*4 cm carbon cloth was placed in the mixed solution and allowed to stand for 4 hours to form ZnCo ZIF-CC. The cloth was then removed and repeatedly washed with deionized water and ethanol, and dried in an oven for later use. Subsequently, 3g of melamine was weighed and placed in a ceramic boat. NCNTs were suspended on both sides of the ceramic boat and placed in the center of a tube furnace. The furnace was heated to 750℃ at 5℃ / min in a N2 atmosphere, held for 2 hours, and then allowed to cool naturally to form nitrogen-doped carbon nanotubes, denoted as NCNTs / CC.

[0064] (II) Hydrothermal Growth of Manganese Metal Oxide Nanoparticles: The total molar amount of potassium permanganate and ruthenium trichloride was controlled to be 0.5 mmol. Detailed steps were as follows: 0.079 g of potassium permanganate was weighed and dissolved in 32 ml of deionized water, and stirred for 15 min. Then, 2 ml of HCl was added dropwise while stirring, and stirring was continued for 10 min. After uniform mixing, the solution was poured into a 50 ml polytetrafluoroethylene (PTFE) liner, and the precursor NCNTs / CC was placed inside the liner. The liner was then tightened and placed in an oven for hydrothermal reaction. The temperature was raised to 120℃ and maintained for 12 h. After natural cooling to room temperature, the nanoparticles were removed. They were washed three times with deionized water and ethanol, and then dried in an oven for later use.

[0065] (III) Carbonization of pure manganese oxide nanoparticles grown on nitrogen-doped carbon nanotubes by PECVD in an oxygen atmosphere: the treatment conditions were a pressure of 20 Pa, a power of 100 W, a temperature of 250 °C, and a time of 5 min, producing a pink glow. The particles were then naturally cooled to room temperature. The resulting oxygen plasma-treated catalyst of pure manganese oxide nanoparticles supported on nitrogen-doped carbon nanotubes was labeled P(O₂)₂. 2 )-MnO x @NCNTs / CC.

[0066] Comparative Example 2:

[0067] The oxygen radio frequency plasma treatment method for loading pure Ru metal oxide nanoparticle catalysts onto nitrogen-doped nanotubes is as follows:

[0068] (1) Growth of nitrogen-doped carbon nanotubes on carbon cloth: Nitrogen-doped carbon nanotubes (NCNTs) were prepared using cobalt nitrate hexahydrate, zinc nitrate hexahydrate, and dimethylimidazole as raw materials. 0.385 g of Co(NO3)2·6H2O and 0.197 g of Zn(NO3)2·6H2O were dissolved in 40 ml of deionized water to form solution A. Then, 1.3 g of dimethylimidazole was dissolved in 40 ml of deionized water to form solution B. After stirring each solution thoroughly, solution A was poured into solution B to form a mixed solution. A 3*4 cm carbon cloth was placed in the mixed solution and allowed to stand for 4 hours to form ZnCo ZIF-CC. The cloth was then removed and repeatedly washed with deionized water and ethanol, and dried in an oven for later use. Subsequently, 3g of melamine was weighed and placed in a ceramic boat. NCNTs were suspended on both sides of the ceramic boat and placed in the center of a tube furnace. The furnace was heated to 750℃ at 5℃ / min in a N2 atmosphere, held for 2 hours, and then allowed to cool naturally to form nitrogen-doped carbon nanotubes, denoted as NCNTs / CC.

[0069] (II) Hydrothermal Growth of Pure Ruthenium Metal Oxide Nanoparticles: The total molar amount of potassium permanganate and ruthenium trichloride was controlled to be 0.5 mmol. Detailed steps were as follows: 0.103 g of ruthenium trichloride was weighed and dissolved in 32 ml of deionized water, and stirred for 15 min. Then, 2 ml of HCl was added dropwise while stirring, and stirring was continued for 10 min. After uniform mixing, the solution was poured into a 50 ml polytetrafluoroethylene (PTFE) liner, and the precursor NCNTs / CC was placed inside the liner. The liner was then tightened and placed in an oven for hydrothermal reaction. The temperature was raised to 120℃ and maintained for 12 h. After natural cooling to room temperature, the nanoparticles were removed. They were washed three times with deionized water and ethanol, and then dried in an oven for later use.

[0070] (III) Carbonization of pure ruthenium metal oxide nanoparticles grown on nitrogen-doped carbon nanotubes was performed using PECVD in an oxygen atmosphere: the treatment conditions were a pressure of 20 Pa, a power of 100 W, a temperature of 250 °C, and a time of 5 min, producing a pink glow. The nanoparticles were then naturally cooled to room temperature. The oxygen plasma-treated pure ruthenium metal oxide nanoparticles loaded on nitrogen-doped carbon nanotubes were obtained and labeled as P(O2)-RuO2. x @NCNTs / CC.

[0071] Comparative Example 3:

[0072] Mn loaded onto nitrogen-doped nanotubes 0.35 Ru 0.15 The specific method for metal oxide nanoparticle catalysts is as follows:

[0073] (1) Growth of nitrogen-doped carbon nanotubes on carbon cloth: Nitrogen-doped carbon nanotubes (NCNTs) were prepared using cobalt nitrate hexahydrate, zinc nitrate hexahydrate, and dimethylimidazole as raw materials. 0.385 g of Co(NO3)2·6H2O and 0.197 g of Zn(NO3)2·6H2O were dissolved in 40 ml of deionized water to form solution A. Then, 1.3 g of dimethylimidazole was dissolved in 40 ml of deionized water to form solution B. After stirring each solution thoroughly, solution A was poured into solution B to form a mixed solution. A 3*4 cm carbon cloth was placed in the mixed solution and allowed to stand for 4 hours to form ZnCo ZIF-CC. The cloth was then removed and repeatedly washed with deionized water and ethanol, and dried in an oven for later use. Subsequently, 3g of melamine was weighed and placed in a ceramic boat. NCNTs were suspended on both sides of the ceramic boat and placed in the center of a tube furnace. The furnace was heated to 750℃ at 5℃ / min in a N2 atmosphere, held for 2 hours, and then allowed to cool naturally to form nitrogen-doped carbon nanotubes, denoted as NCNTs / CC.

[0074] (II) Hydrothermal Growth of Manganese Ruthenium Metal Oxide Nanoparticles: The total molar amount of potassium permanganate and ruthenium trichloride was controlled to be 0.5 mmol. Detailed steps were as follows: 0.0553 g of potassium permanganate and 0.0311 g of ruthenium trichloride were weighed and dissolved in 32 ml of deionized water, and stirred for 15 min; then, 2 ml of HCl was added dropwise while stirring, and stirring was continued for 10 min; after uniform mixing, the mixture was poured into a 50 ml polytetrafluoroethylene (PTFE) inner liner, and the precursor NCNTs / CC was placed inside the liner, tightened, and placed in an oven for hydrothermal reaction. The temperature was raised to 120℃ and kept at that temperature for 12 h. After natural cooling to room temperature, the nanoparticles were removed. They were washed three times with deionized water and ethanol, dried in an oven, and labeled as Mn. 0.35 Ru 0.15 O x @NCNTs / CC.

[0075] OER (Oxygen Evolution Rate) catalytic performance evaluation:

[0076] The OER test used a commercial RuO2 catalyst, prepared as follows: 5 mg of powdered sample was added to a mixture of 50 μL of 5% Nafion solution and 950 μL of isopropanol, and treated in an ultrasonic cleaner for 20 min to form a homogeneous slurry. The same loading of solution as the final sample was then added dropwise to a carbon cloth substrate for testing.

[0077] The final sample P(O2)-Mn was tested using an electrolytic cell. 0.35 Ru 0.15 O x The OER of @NCNTs / CC and the control sample, as well as the linear sweep voltammetry LSV curves of commercial RuO2, are shown in the figure. Figure 5 As shown. P(O2)-Mn 0.35 Ru 0.15 O x The @NCNTs / CC sample exhibited high OER electrocatalytic activity, requiring only a potential of 98.5 mV to drive a 10 mA cm⁻¹ electrocatalysis. -2 The current density is higher, and its electrocatalytic activity is higher than that of the comparative sample pure manganese P(O2)-MnO. x @NCNTs / CC and pure ruthenium P(O2)-RuO x @NCNTs / CC exhibit catalytic performance far exceeding that of commercial RuO2, and also boasts a high current density reaching 300 mA cm⁻¹. -2 .

[0078] Chronopotentiometric method for testing long-term stability:

[0079] The stability of the material was further investigated using chronopotential electrochemical testing with an electrolysis current of 10 mA cm⁻¹. -2 The final sample P(O2)-Mn was tested using chronopotentiometric method.0.35 Ru 0.15 O x @NCNTs / CC and the control sample pure manganese P(O2)-MnO x @NCNTs / CC and pure ruthenium P(O2)-RuO x Long-term stability of @NCNTs / CC and untreated samples with oxygen plasma. Results are as follows. Figure 6 As shown, compared to the control sample, the final sample P(O2)-Mn 0.35 Ru 0.15 O x @NCNTs / CC under acidic conditions for 98 hours showed only a small voltage increase, increasing by a mere 70 mV. This demonstrates that the prepared oxygen radio frequency plasma treatment catalyst, supported on nitrogen-doped nanotubes grown on carbon cloth, exhibits excellent catalytic activity and long-term stability, while the manganese doping reduces the amount of precious metal used.

[0080] The specific embodiments described above do not constitute a limitation on the scope of protection of this invention. Those skilled in the art should understand that various modifications, combinations, sub-combinations, and substitutions can occur depending on design requirements and other factors. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of this invention should be included within the scope of protection of this invention.

Claims

1. A catalyst for a proton exchange membrane water electrolysis hydrogen production device, characterized in that its structure uses nitrogen-doped carbon nanotubes grown on carbon cloth as a conductive network, and is characterized in that: Manganese-ruthenium metal oxide nanoparticles are uniformly loaded onto a conductive network after hydrothermal reaction and radio frequency enhanced plasma chemical vapor deposition in an oxygen atmosphere; the molar ratio of manganese to ruthenium is 5-9:1-5.

2. The method for preparing a catalyst for a proton exchange membrane water electrolysis hydrogen production device as described in claim 1, characterized in that, The specific steps include the following: (i) Growth of nitrogen-doped carbon nanotubes on carbon cloth; (ii) Loading manganese ruthenium metal oxide nanoparticles via hydrothermal reaction; (iii) Radio frequency enhanced plasma chemical vapor deposition process in an oxygen atmosphere.

3. The method for preparing a catalyst for a proton exchange membrane water electrolysis hydrogen production device as described in claim 2, characterized in that, In step (ii), a certain amount of potassium permanganate and ruthenium trichloride are weighed, dissolved in deionized water, and stirred thoroughly. A measured amount of HCl is added dropwise while stirring. After the solution is mixed evenly, it is poured into the polytetrafluoroethylene liner of the oven. Then, the carbon cloth with nitrogen-doped carbon nanotubes prepared in step (i) is placed in the solution. After the oven is closed, a hydrothermal reaction is carried out. The temperature is raised to 120℃ and maintained for 12 hours. After naturally cooling to room temperature, it is taken out and washed three times with deionized water and ethanol, and then dried. The molar ratio of potassium permanganate to ruthenium trichloride is 5-9:1-5.

4. The method for preparing a catalyst for a proton exchange membrane water electrolysis hydrogen production device as described in claim 3, characterized in that, The molar ratio of potassium permanganate to ruthenium trichloride is 7:

3.

5. The method for preparing a catalyst for a proton exchange membrane water electrolysis hydrogen production device as described in claim 2, characterized in that, In step (iii), the gas pressure of the radio frequency enhanced plasma chemical vapor deposition treatment is 20 Pa, the radio frequency power is 40 W to 130 W, the time is 5 min to 20 min, and the temperature is 200 ℃ to 350 ℃.

6. The method for preparing a catalyst for a proton exchange membrane water electrolysis hydrogen production device as described in claim 5, characterized in that, The radio frequency enhanced plasma chemical vapor deposition process was performed with a radio frequency power of 100W, a time of 5 minutes, and a temperature of 250℃.

7. The application of the catalyst as described in claim 1 as a catalyst for the oxygen evolution reaction in proton exchange membrane water electrolysis.

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