Alkaline HER catalyst containing high-valence Ru species as well as preparation method and application of alkaline HER catalyst

Abstract

The invention belongs to the technical field of electro-catalysis, and particularly relates to a preparation method and application of a Ru-based supported HER catalyst. The catalyst is a KTN-supported Ru-based catalyst, and Ru is highly dispersed in a KTN substrate to form a supported Ru / KTN structure. The catalyst is annealed at different temperatures and in different atmospheres, so that Ru is uniformly loaded on the surface of the carrier, and meanwhile, the content of high-valence Ru is optimized. By adjusting the hydrothermal time and the proportion of the precursor, the composite heterojunction carrier is obtained, and the conductivity of the oxide carrier is greatly improved. The HER activity and durability of the catalyst in an alkaline environment are remarkably enhanced through the synergistic effect, meanwhile, the use amount of precious metal Ru is greatly reduced, and the catalyst has excellent cost performance and industrial application prospects.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of electrocatalysis, and particularly relates to a high-valence Ru species alkaline HER catalyst and a preparation method and application thereof. BACKGROUND

[0002] With the transformation of global energy structure to clean, hydrogen energy as an efficient, zero-carbon energy carrier has attracted much attention. Water electrolysis is an important technical route for the preparation of "green hydrogen", and the cathodic hydrogen evolution reaction (HER) in alkaline conditions is a key bottleneck restricting energy efficiency because it involves a water molecule dissociation step with slow kinetics. In the HER catalyst, platinum (Pt) has excellent performance but high cost, which limits its large-scale application. Ruthenium (Ru), as a platinum group metal, has similar electronic structure to Pt, suitable hydrogen adsorption free energy, and lower cost, and is considered as a potential alternative material. However, Ru still faces challenges such as few active sites and insufficient stability in alkaline HER. In the alkaline HER reaction, the Volmer step (water molecule dissociation) has a high energy barrier and is often the rate-controlling step. Therefore, an ideal catalyst needs to have both efficient water dissociation ability and optimized hydrogen adsorption behavior.

[0003] Although the supported Ru catalyst increases the specific surface area by improving the Ru particle dispersion and reducing the Ru particle size, thereby improving the metal utilization and catalytic performance, its activity and stability in alkaline medium are still insufficient to meet the actual application requirements. In addition, although the use of metal oxide supports effectively improves the corrosion resistance of the supports, the poor conductivity of the oxides also limits the overall activity of the catalyst. Therefore, constructing a Ru-based catalyst with high-density active sites, excellent water dissociation ability, good conductivity and long-term stability is a key direction to promote the development of alkaline water electrolysis technology. Studies have shown that high-valence Ru species can effectively promote the adsorption and dissociation of water molecules, thereby significantly improving the alkaline HER efficiency. SUMMARY

[0004] In order to solve the problems of insufficient catalytic activity of Ru-based catalysts in alkaline medium for HER, difficulty in controlling Ru valence during synthesis, and large amount of noble metal and high cost in the prior art, the purpose of the present application is to develop a new type of electrolytic water hydrogen production catalyst containing high-valence Ru species. By optimizing the support structure and controlling the Ru valence, the catalytic performance and durability of the catalyst in the electrolytic water hydrogen production reaction are significantly improved, overcoming the deficiencies in the prior art, and having important application value and industrialization prospect.

[0005] In order to achieve the above-mentioned purpose, the technical scheme adopted by the present application is as follows: The first aspect of the present application discloses a preparation method of an alkaline HER catalyst containing high-valence Ru species, comprising the following steps: (1): dispersing MAX phase titanium aluminum nitride (Ti2AlN) particles in an alkaline hydrothermal environment to react, allowing partial etching and conversion of the surface of Ti2AlN and in-situ generation of layered potassium titanate, forming a layered heterojunction composite carrier with titanium aluminum nitride as the intermediate layer matrix and layered potassium titanate grown on the surface, denoted as KTN; (2): uniformly mixing ruthenium trichloride and KTN to obtain a product RuCl3 / KTN composite material; (3): heat treating RuCl3 / KTN in air and a reducing atmosphere in sequence, and grinding to obtain Ru / KTN-T, which is the Ru-based supported HER electrocatalyst; The temperature of the heat treatment in air in step (3) is 150-250 ℃, and the time is 1-3 h; The temperature of the heat treatment in a reducing atmosphere in step (3) is 200-400 ℃, and the time is 1-3 h.

[0006] By controlling the annealing at different temperatures and atmospheres, Ru is uniformly supported on the surface of the carrier, the interaction between the nanomaterial and the carrier is strengthened, the content of high-valence Ru is optimized, the HER activity and durability in an alkaline environment are significantly enhanced, the use amount of noble metal Ru is greatly reduced, and the Ru-based supported HER electrocatalyst has excellent cost performance and industrial application prospect.

[0007] The temperature of the reaction in the alkaline hydrothermal environment in step (1) is 150 ℃, and the time is 8-20 h. The alkaline solution selected is potassium hydroxide (KOH) aqueous solution. The mass ratio of titanium aluminum nitride (Ti2AlN) to potassium hydroxide (KOH) is 1:21-1:84.

[0008] The washing method in step (1) is to use deionized water to filter.

[0009] The mass ratio of RuCl3 to KTN in step (2) is 1:1.

[0010] The drying method in step (2) is to dry in an oven at 80 ℃ for 12-24 h.

[0011] In step (3), the heating rate of the heat treatment in air is 2 ℃ / min.

[0012] In step (3), the reducing atmosphere is a hydrogen-argon atmosphere, and the heating rate of the heat treatment is 2 ℃ / min.

[0013] The layered potassium titanate is potassium octatitanate K2Ti8O 17 .

[0014] The second aspect of the present application discloses a basic HER electrocatalyst containing high-valence Ru species, a composite carrier: the composite carrier is a layered heterojunction structure with MAX phase aluminum titanium nitride as the middle sheet layer and the layered potassium titanate grown in situ on the surface of the aluminum titanium nitride as the outer layer on both sides. Active component: the active component is loaded in the form of nanoparticles on the surface and between the sheet layers of the composite carrier, and contains a mixed state of metallic Ru(0) and high-valence Ru(n+) species.

[0015] The layered potassium titanate is potassium octatitanate K2Ti8O 17 .

[0016] The third aspect of the present application discloses the application of the above Ru-based supported HER electrocatalyst in electrolysis of water.

[0017] Compared with the prior art, the present application has the following beneficial effects: 1. The present application develops a two-step heat treatment process (air oxidation first and hydrogen-argon reduction later), successfully prepares a HER electrocatalyst with KTN (K2Ti8O 17 and Ti2AlN composite material) as the carrier and highly dispersed metallic ruthenium (Ru) as the active center. The prepared Ru / KTN-T catalyst exhibits excellent HER activity in alkaline medium. The overpotential thereof is as low as 40.6 mV and 60.6 mV at current densities of 10 mA / cm 2 and 20 mA / cm 2 , respectively.

[0018] 2. The Ru / KTN-T catalyst prepared in the present application maintains performance stability in continuous testing for up to 100 hours and has long-term operation stability.

[0019] 3. The broadened diffraction peak of metallic Ru in the XRD pattern and the XPS analysis show that in the catalyst prepared in the present application, Ru is highly dispersed in the form of fine nanoparticles on the surface of the KTN carrier, exposes more active sites, strengthens the interaction between Ru and the carrier, effectively improves the dispersion and stability of Ru, and significantly enhances the HER activity and durability of Ru in alkaline environment.

[0020] 4. The preparation method of the present application is simple, the aluminum titanium nitride raw material is abundant and low in price, and the overall catalyst manufacturing cost is greatly reduced. BRIEF DESCRIPTION OF DRAWINGS

[0021] Figure 1 is the preparation flowchart of Example 1.

[0022] Figure 2X-ray diffraction (XRD) pattern of a KTN sample of a composite of titanium aluminum nitride (Ti2AlN) prepared according to step (1) of Example 1 and potassium octatitanate (K2Ti8O 17 X-ray diffraction (XRD) pattern of a Ru / KTN-T sample prepared according to Example 1.

[0023] Figure 3 X-ray diffraction (XRD) pattern of a Ru / KTN-T sample prepared according to Example 1.

[0024] Figure 4 Transmission electron microscopy (TEM) image of a Ru / KTN-T sample prepared according to Example 1.

[0025] Figure 5 X-ray diffraction (XRD) pattern of a Ru / KTN-200 sample, a Ru / KTN-300 sample, and a Ru / KTN-400 sample prepared according to Comparative Example 1, Comparative Example 2, and Comparative Example 3.

[0026] Figure 6 X-ray diffraction (XRD) pattern of a Ru / KTN-Air sample prepared according to Comparative Example 4.

[0027] Figure 7 X-ray photoelectron spectroscopy (XPS) pattern of a catalyst Ru / KTN-T sample prepared according to Example 1, a catalyst Ru / KTN-300 sample prepared according to Comparative Example 2, and a catalyst Ru / KTN-Air sample prepared according to Comparative Example 4.

[0028] Figure 8 Linear sweep voltammetry (LSV) voltammogram of a Ru / KTN-T sample, a Ru / KTN-200 sample, a Ru / KTN-300 sample, and a Ru / KTN-400 sample prepared according to Example 1, Comparative Example 1, Comparative Example 2, and Comparative Example 3.

[0029] Figure 9 Impedance plot of Example 1, commercial titanium aluminum nitride (Ti2AlN), commercial potassium octatitanate (K2Ti8O 17 ), and a ball-milled mixture of the two (Comparative Example 7).

[0030] Figure 10 Stability test plot of a Ru / KTN-T sample prepared according to Example 1.

[0031] Figure 11 Scanning electron microscopy (SEM) image of titanium aluminum nitride particles prepared according to Example 1. DETAILED DESCRIPTION

[0032] The technical solutions of the present application are described in detail below in combination with the drawings and examples, but the present application is not limited to the scope of the described examples. The process parameters not mentioned in the examples of the present application can be performed according to conventional methods, and the raw materials used can be obtained through commercial channels.

[0033] Example 1: (1) 1 g of titanium aluminum nitride was added to 150 mL of 5 M KOH solution, the mixture was stirred for 30 minutes to form a suspension, which was then transferred to a Teflon hot liquid container and kept at 150 °C for 12 h. After the reaction was completed, the obtained solid was separated, washed with deionized water, and dried at 60 °C to obtain a gray solid sample of titanium aluminum nitride (Ti2AlN) and potassium octatitanate (K2Ti8O 17 ) composite, named KTN.

[0034] In step (1), the titanium aluminum nitride is a particulate MAX phase with an average particle size of 3.63 μm, D50 = 3.40 μm, and large particles are removed through a 500 mesh sieve. Its particle morphology is shown in Figure 11 .

[0035] (2) 0.5 g of RuCl3 was dissolved in 50 mL of deionized water, stirred for 30 minutes, and then 0.5 g of KTN was added and stirred for 12 h. After drying in a forced air drying oven at 80 °C, RuCl3 / KTN was obtained.

[0036] (3) The above obtained RuCl3 / KTN sample was first placed in a muffle furnace and annealed at 200 °C for 2 h at a heating rate of 2 °C / min, and then placed in a tube furnace and annealed at 300 °C for 2 h under a flowing hydrogen-argon (5 / 95) atmosphere at a heating rate of 2 °C / min to obtain a Ru / KTN-T sample.

[0037] Example 2: (1) 0.5 g of titanium aluminum nitride (500 mesh sieve) was added to 150 mL of 5 M KOH solution, the mixture was stirred for 30 minutes to form a suspension, which was then transferred to a Teflon hot liquid container and kept at 150 °C for 12 h. After the reaction was completed, the obtained solid was separated, washed with deionized water, and dried at 60 °C to obtain a gray solid sample of titanium aluminum nitride (Ti2AlN) and potassium octatitanate (K2Ti8O 17 ) composite, named KTN.

[0038] (2) Same as step (2) of Example 1; (3) Same as step (3) of Example 1.

[0039] Example 3: (1) 2 g of titanium aluminum nitride (500 mesh sieve) was added to 150 mL of 5 M KOH solution, the mixture was stirred for 30 minutes to form a suspension, which was then transferred to a Teflon hot liquid container and kept at 150 °C for 12 h. After the reaction was completed, the obtained solid was separated, washed with deionized water, and dried at 60 °C to obtain a gray solid sample of a composite of titanium aluminum nitride (Ti2AlN) and potassium octatitanate (K2Ti8O 17 ), named KTN.

[0040] (2) The same as step (2) of Example 1; (3) The same as step (3) of Example 1.

[0041] Example 4: (1) 2 g of titanium aluminum nitride (500 mesh sieve) was added to 150 mL of 5 M KOH solution, the mixture was stirred for 30 minutes to form a suspension, which was then transferred to a Teflon hot liquid container and kept at 150 °C for 12 h. After the reaction was completed, the obtained solid was separated, washed with deionized water, and dried at 60 °C to obtain a gray solid sample of a composite of titanium aluminum nitride (Ti2AlN) and potassium octatitanate (K2Ti8O 17 ), named KTN.

[0042] (2) The same as step (2) of Example 1; (3) The same as step (3) of Example 1.

[0043] Example 5: (1) 2 g of titanium aluminum nitride (500 mesh sieve) was added to 150 mL of 5 M KOH solution, the mixture was stirred for 30 minutes to form a suspension, which was then transferred to a Teflon hot liquid container and kept at 150 °C for 12 h. After the reaction was completed, the obtained solid was separated, washed with deionized water, and dried at 60 °C to obtain a gray solid sample of a composite of titanium aluminum nitride (Ti2AlN) and potassium octatitanate (K2Ti8O 17 ), named KTN.

[0044] (2) The same as step (2) of Example 1; (3) The same as step (3) of Example 1.

[0045] Comparative Example 1: (1) The same as step (1) of Example 1; (2) The same as step (2) of Example 1; (3) The above obtained RuCl3 / KTN sample was placed in a tube furnace and annealed at 200 °C for 2 h under a flowing hydrogen-argon (5 / 95) atmosphere at a heating rate of 2 °C / min to obtain a Ru / KTN-200 sample.

[0046] Comparative Example 2: (1) The same as step (1) of Example 1; (2) The same as step (2) of Example 1; (3) The above obtained RuCl3 / KTN sample was placed in a tube furnace, and annealed at 300 ℃ for 2 h under flowing hydrogen-argon (5 / 95) atmosphere at a heating rate of 2 ℃ / min to obtain a Ru / KTN-300 sample.

[0047] Comparative Example 3: (1) The same as step (1) of Example 1; (2) The same as step (2) of Example 1; (3) The above obtained RuCl3 / KTN sample was placed in a tube furnace, and annealed at 400 ℃ for 2 h under flowing hydrogen-argon (5 / 95) atmosphere at a heating rate of 2 ℃ / min to obtain a Ru / KTN-400 sample.

[0048] Comparative Example 4: (1) The same as step (1) of Example 1; (2) The same as step (2) of Example 1; (3) The above obtained RuCl3 / KTN sample was placed in a muffle furnace, and annealed at 200 ℃ for 2 h at a heating rate of 2 ℃ / min to obtain a Ru / KTN-Air sample.

[0049] Comparative Example 5: (1) The same as step (1) of Example 1; (2) The same as step (2) of Example 1; (3) The above obtained RuCl3 / KTN sample was first placed in a muffle furnace, and sintered at 300 ℃ for 2 h, and then placed in a tube furnace, and annealed at 300 ℃ for 2 h under flowing hydrogen-argon (5 / 95) atmosphere at a heating rate of 2 ℃ / min to obtain a Ru / KTN-T2 sample.

[0050] Comparative Example 6: (1) The same as step (1) of Example 1; (2) The same as step (2) of Example 1; (3) The above obtained RuCl3 / KTN sample was first placed in a muffle furnace, and sintered at 400 ℃ for 2 h, and then placed in a tube furnace, and annealed at 300 ℃ for 2 h under flowing hydrogen-argon (5 / 95) atmosphere at a heating rate of 2 ℃ / min to obtain a Ru / KTN-T3 sample.

[0051] Comparative Example 7: Commercially available titanium aluminum nitride (Ti2AlN) and commercially available potassium octatitanate (K2Ti8O 17 ) were weighed and mixed in a mass ratio of 1:1, then ball-milled for 4 hours to obtain a mixture of Ti2AlN and K2Ti8O 17 .

[0052] The samples prepared in Examples 1-5 and Comparative Examples 1-6 were subjected to structural and performance characterization, and the results are as follows: The composite carrier of titanium aluminum nitride (Ti2AlN) and potassium octatitanate (K2Ti8O 17 ) can be obtained in Examples 1-5. That is, in step (1), the mass ratio of the precursor titanium aluminum nitride (Ti2AlN) and potassium hydroxide (KOH) is in the range of 1:20 ~ 1:80, and the hydrothermal time is in the range of 8 ~ 20 hours.

[0053] Figure 2 The XRD pattern of the sample obtained in step (1) of Example 1 proves that KTN is a composite of titanium aluminum nitride (Ti2AlN) and potassium octatitanate (K2Ti8O 17 ).

[0054] Figure 3 The XRD pattern of the catalyst Ru / KTN-T sample and the KTN sample prepared in Example 1. The XRD diffraction peaks of the Ru / KTN-T sample correspond to Ru (JCPDS No. 06-0663) and the diffraction peaks of the KTN sample, which confirms the presence of both Ru and KTN components in the sample, indicating that Ru is successfully loaded on the KTN carrier.

[0055] Figure 4 The TEM image of the catalyst Ru / KTN-T sample prepared in Example 1. It can be observed that the sample presents a sheet structure, with the lattice fringes of elemental Ru, titanium aluminum nitride (Ti2AlN), and potassium octatitanate (K2Ti8O 17 ), again proving that the carrier obtained in step (1) of Example 1 is a composite.

[0056] Figure 5 The XRD pattern of the Ru / KTN-200 sample, the Ru / KTN-300 sample, and the Ru / KTN-400 sample prepared in Comparative Example 1, Comparative Example 2, and Comparative Example 3, respectively. This confirms the presence of both Ru and KTN components in the sample.

[0057] Figure 6XRD pattern of Ru / KTN-Air sample prepared for Comparative Example 4. The XRD diffraction peaks of Ru / KTN-Air sample do not exist the diffraction peaks corresponding to the standard card of Ru (JCPDS No. 06-0663), but only correspond to the diffraction peaks of KTN sample, i.e. the oxidation step does not have a reduction effect on RuCl3.

[0058] Figure 7 XPS patterns of catalyst Ru / KTN-T sample prepared for Example 1, catalyst Ru / KTN-300 sample prepared for Comparative Example 2, and catalyst Ru / KTN-Air sample prepared for Comparative Example 4. This proves that the oxidation step increases the content of high-valence Ru(n+) in the final sample Ru / KTN-T, which can promote the ability of the catalyst to crack water molecules and help to improve the basic HER activity.

[0059] In order to test the basic HER electrochemical performance using a three-electrode system, the catalyst needs to be further prepared into a catalyst ink. The specific catalyst ink formula is: 2 mg of catalyst is dispersed in a mixed solution (100 μL of isopropyl alcohol and 100 μL of 0.5% Nafion solution) and ultrasonically dispersed for 1 h to complete dispersion.

[0060] At room temperature, the electrochemical performance of the catalyst is tested using a three-electrode system, and the carbon paper (0.5*1 cm 2 ) to which the catalyst ink is dropped is used as the working electrode, the Pt mesh is used as the counter electrode for HER test, and the Hg / HgO is used as the reference electrode. In 1 M KOH aqueous solution, the scanning rate is 5 mV / s, and the LSV curve is recorded.

[0061] Figure 8 The catalyst Ru / KTN-T sample prepared for Example 1, the catalyst Ru / KTN-200 sample prepared for Comparative Example 1, the catalyst Ru / KTN-300 sample prepared for Comparative Example 2, and the catalyst Ru / KTN-400 sample prepared for Comparative Example 3. The HER performance of the catalyst was evaluated in 1 M KOH solution using a conventional three-electrode structure. The Ru / KTN-T catalyst only needs a moderate overpotential of 60.6 mV to produce a current density of 20 mA / cm 2 The overpotential is significantly lower than Comparative Example 1 (Ru / KTN-200, 88.6 mV), Comparative Example 2 (Ru / KTN-300, 78.6 mV), and Comparative Example 3 (Ru / KTN-400, 88.6 mV), as shown in Table 1.

[0062] Ti2AlN (MAX phase) will be selectively etched under strong alkaline hydrothermal conditions, usually Al element will be partially etched, while Ti element reacts with K + , OH - in solution to form potassium titanate on the surface of the residual Ti2AlN crystal. This process naturally tends to form an intermediate layer (Ti2AlN not completely reacted) - outer layer (newly generated K2Ti8O 17 ) sandwich-like sheet structure.

[0063] Figure 9 Impedance plots of Example 1, commercial Ti2AlN, commercial K2Ti8O 17 , and ball-milled mixture of both (Comparative Example 7). Ti2AlN shows typical metallic conductivity, K2Ti8O 17 itself is poorly conductive, while KTN shows significantly better conductivity than pure Ti2AlN, pure K2Ti8O 17 , and their physical mixture. As in Comparative Example 7, if Ti2AlN is simply physically mixed with Ti2AlN, electron transport will be hindered, and the conductivity of the mixture obtained by physical mixing will be between the two. While the conductivity of KTN is greatly improved, which strongly indicates that a tight, well-coupled heterojunction interface is formed between the highly conductive Ti2AlN (intermediate layer) and the surface-modified K2Ti8O 17 (outer sheet layer), which is the typical advantage of the sandwich structure. Physical mixtures cannot achieve such a tight interface contact and electron synergistic effect. Therefore, it can be fully proved that the hydrothermal process of Example 1, Step 1, can obtain a sandwich heterojunction structure.

[0064] In Example 1, the Ti2AlN powder used has an average particle size of 3.63 μm, a volume particle size distribution median D50 of 3.40 μm, and has been passed through a 500-mesh sieve (corresponding to a sieve mesh size of about 25 μm) to ensure that particles with excessively large particle size are removed. Precise control of the precursor particle size is crucial because it directly affects the specific surface area and reaction interface. Smaller particle size (micron level) provides a larger reaction specific surface area, so that in the subsequent hydrothermal step, potassium hydroxide (KOH) solution can more fully react with Al atoms on the surface and edges of Ti2AlN sheets.

[0065] To achieve controllable synthesis of the layered heterojunction composite carrier (KTN) structure, the key is to control the degree of partial etching of the MAX phase Ti2AlN precursor and the in-situ generation of potassium titanate, so as to retain the conductive Ti2AlN intermediate layer while building the potassium titanate outer layer with the function of promoting hydrolysis. This process is co-regulated by multiple variables, rather than relying on a single fixed condition: Precursor particle size: Particle size determines the size of the accessible reaction interface.

[0066] Alkaline solution concentration: KOH concentration directly affects OH - concentration and the alkalinity of the reaction system, which is a key chemical potential factor driving Al layer etching and participating in the formation of potassium titanate.

[0067] Hydrothermal reaction temperature and time: Temperature provides the activation energy required for the reaction, and time determines the depth of the reaction process; both together control the kinetics of the etching and in-situ crystallization reaction.

[0068] Therefore, under the premise that the target product is "a layered heterojunction composite carrier with aluminum titanium nitride as the intermediate layer matrix and a surface grown layered potassium titanate", the skilled person in the art can completely control the crystallinity, coverage and morphology of the potassium titanate and the final heterojunction by selecting and adjusting within the known synergistic relationship framework of the above variables (precursor particle size, type and concentration of alkaline compound, hydrothermal temperature and time) through routine experiments, thereby obtaining the expected KTN carrier. This principle-based adjustability is the advantage of the preparation method of the present application, and also means that the protection scope is not limited to a specific set of example parameters.

[0069] Table 1

[0070] From the data in Table 1, The overpotential of Example 1 (Ru / KTN-T) prepared in Example 1 at 10 mA / cm 2 , 20 mA / cm 2 , 50 mA / cm 2 , and 100 mA / cm 2 current density was significantly lower than that of other samples (Comparative Examples 1-6), indicating that it had the optimal HER catalytic activity.

[0071] Figure 10 The HER performance stability diagram of the catalyst Ru / KTN-T sample prepared in Example 1 of the present application can be seen, and the Ru / KTN-T sample prepared in the present application has a stability of up to 100 h.

[0072] From the comparative data of Example 1 and Comparative Examples 1-3, the two-step heat treatment strategy of "air first and then hydrogen argon" used in Example 1 can increase the content of high-valence Ru (n+) in the sample, thereby significantly improving the catalytic activity and stability of the catalyst in alkaline HER, which is much better than Comparative Examples 1-3 which only perform one-step reduction treatment.

[0073] From the results of comparing example 1 with comparative example 4, the core difference between them is the heat treatment atmosphere of step (3) of example 1, which directly determines the chemical state of Ru in the final product. Comparative example 4 uses a one-step oxidation treatment method, and the RuCl3 in the final sample is not reduced to metallic Ru, and the Ru species in the sample still exists in ionic state, which is beneficial to the water molecule cracking step, but is not conducive to the proton reduction and hydrogen desorption steps in the basic HER. The first step of air annealing in the present application can oxidize the Ru precursor to ultra-small RuCl x clusters and preliminarily anchor on the carrier. The second step of annealing under a hydrogen-argon atmosphere reduces part of the high-valence Ru species to metallic Ru with high hydrogen desorption activity, while preserving the high-valence oxidized Ru with high water splitting activity, and successfully prepares a high-performance basic HER catalyst.

[0074] From the results of comparing example 1 with comparative example 5 and comparative example 6, although the two-step sintering method helps to improve the overall efficiency of the basic HER, the excessively high oxidation temperature will reduce the content of metallic Ru in the final sample, which leads to the reduction of the overall catalytic activity, that is, there is a synergistic effect between the oxidized Ru and the metallic Ru.

[0075] The present application is not limited to the above-mentioned embodiments, and any changes in shape or structure fall within the scope of the present application. The scope of protection of the present application is defined by the appended claims, and those skilled in the art can make various changes, modifications, substitutions, combinations and simplifications to these embodiments without departing from the principles and essence of the present application.

Claims

1. A method for preparing a Ru-based supported alkaline HER electrocatalyst, characterized in that, Comprising the following steps: (1): dispersing MAX phase titanium aluminum nitride (Ti2AlN) particles in an alkaline hydrothermal environment to react, allowing the surface of Ti2AlN to be partially etched and converted and in-situ generating layered potassium titanate, forming a layered heterojunction composite carrier with titanium aluminum nitride as the intermediate layer matrix and layered potassium titanate grown on the surface, denoted as KTN; (2): uniformly mixing ruthenium trichloride and KTN to obtain a product RuCl3 / KTN composite material; (3): heat treating RuCl3 / KTN in air and reducing atmosphere in sequence, and grinding to obtain Ru / KTN-T, which is the Ru-based supported HER electrocatalyst; The temperature of the heat treatment in air in step (3) is 150-250 ℃, and the time is 1-3 h; The temperature of the heat treatment in reducing atmosphere in step (3) is 200-400 ℃, and the time is 1-3 h.

2. The method for preparing a Ru-based supported HER electrocatalyst according to claim 1, characterized in that, The temperature of the reaction in the alkaline hydrothermal environment in step (1) is 150 ℃, and the time is 8-20 h. The alkaline solution selected is potassium hydroxide (KOH) aqueous solution. The mass ratio of titanium aluminum nitride (Ti2AlN) to potassium hydroxide (KOH) is 1:21-1:

84.

3. The method for preparing a Ru-based supported HER electrocatalyst according to claim 1, characterized in that, The particle size of the titanium aluminum nitride particles is ≤25 µm (D100 ≤ 25 µm).

4. The method for preparing a Ru-based supported HER electrocatalyst according to claim 1, characterized in that, The mixing method in step (2) is to uniformly mix ruthenium trichloride and KTN in a solvent, and then dry to obtain the product RuCl3 / KTN composite material.

5. The method for preparing a Ru-based supported HER electrocatalyst according to claim 1, characterized in that, The mass ratio of ruthenium trichloride to KTN in step (2) is 1:

1.

6. The method for preparing a Ru-based supported HER electrocatalyst according to claim 1, characterized in that, In step (3), the heating rate of the heat treatment in air is 2 ℃ / min. In step (3), the reducing atmosphere is hydrogen-argon atmosphere, and the heating rate of the heat treatment is 2 ℃ / min.

7. The method for preparing a Ru-based supported HER electrocatalyst according to claim 1, characterized in that, The layered potassium titanate is potassium octatitanate K2Ti8O 17 .

8. A Ru-based supported HER electrocatalyst characterized in that, Comprising: Composite carrier: the composite carrier is a layered heterojunction structure with MAX phase titanium aluminum nitride as the intermediate sheet layer and layered potassium titanate in-situ grown on the surface of the titanium aluminum nitride as the two-side outer layer; Active component: the active component is loaded in the form of nanoparticles on the surface of the composite carrier and between the sheet layers, and contains mixed states of metallic Ru(0) and high-valence Ru(n+) species.

9. The Ru-based supported HER electrocatalyst of claim 8, wherein, The layered potassium titanate is potassium octatitanate K2Ti8O 17 .

10. The Ru-based supported HER electrocatalyst according to claim 8 or 9 for use in alkaline electrolytic water.

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