A catalyst for achieving efficient hydrogen evolution by regulating the electronic effect of Ru@NC core-shell heterogeneous interface and its preparation method

Abstract

The present invention discloses a catalyst for achieving efficient hydrogen evolution by regulating the electronic effect of a Ru@NC core-shell heterogeneous interface and a preparation method thereof, belonging to the technical field of hydrogen evolution catalysts. The present invention provides a core-shell heterogeneous structure hydrogen evolution catalyst in which a metal Ru cluster is coated on a three-dimensional porous nitrogen-doped carbon layer (Ru@NC), and the electronic structure of the heterojunction interface is regulated to effectively regulate the d-band center of the Ru metal site and the adsorption / desorption of reaction intermediates, thereby reducing the reaction energy barrier, optimizing the intrinsic activity of the Ru site, and improving the HER performance.

Description

Technical Field

[0001] The present invention belongs to the technical field of hydrogen evolution catalysts, and in particular relates to a catalyst for achieving efficient hydrogen evolution by regulating the electronic effect of a Ru@NC core-shell heterogeneous interface and a preparation method thereof. Background Art

[0002] Hydrogen has the advantages of high calorific value, clean and pollution-free, and zero carbon emissions. Water electrolysis, as a promising large-scale high-purity, low-carbon hydrogen production technology, includes the anode oxygen evolution reaction (OER) and the cathode hydrogen evolution reaction (HER), and has attracted much attention. Considering the large number of available alkaline and efficient OER electrocatalysts, its cathode HER process still requires scarce and expensive platinum (Pt)-based catalysts to drive it, resulting in high electrolysis costs.

[0003] Currently, the low price of Ru (only about 5% of Pt) and Pt (62 kcal·mol -1 ) Similar metal-hydrogen bond energy (65 kcal·mol -1 ) is considered to be a favorable alternative to Pt-based HER catalysts. Alkaline HER involves water dissociation and hydrogen adsorption. In existing schemes, Ru clusters can effectively drive the former, but their strong binding (Ru-H bond) with the adsorbed hydrogen (*H) of the reaction intermediate can hinder the desorption of hydrogen and poison the active sites. Although Ru single-atom (RuSA) catalysts have suitable hydrogen adsorption capacity, their water dissociation ability is poor. Summary of the invention

[0004] In order to solve the above technical problems, the present invention proposes a catalyst for achieving efficient hydrogen evolution by regulating the electronic effect of Ru@NC core-shell heterogeneous interface and a preparation method thereof.

[0005] To achieve the above object, the present invention provides the following technical solutions:

[0006] One of the technical solutions of the present invention:

[0007] The present invention provides a catalyst for achieving efficient hydrogen evolution by regulating the electronic effect of Ru@NC core-shell heterogeneous interface, which is a core-shell heterogeneous structure in which metal Ru clusters are coated on a three-dimensional porous nitrogen-doped carbon layer (Ru@NC).

[0008] The present invention provides a core-shell heterostructure hydrogen evolution catalyst in which a metal Ru cluster is coated on a three-dimensional porous nitrogen-doped carbon layer (Ru@NC). By regulating the electronic structure of the heterojunction interface, the d-band center of the Ru metal site and the adsorption / desorption of reaction intermediates are effectively regulated, the reaction energy barrier is reduced, the intrinsic activity of the Ru site is optimized, and the HER performance is improved.

[0009] The second technical solution of the present invention:

[0010] The present invention provides a method for preparing the catalyst, comprising the following steps:

[0011] Dissolve cyanamide in methanol to form a uniform solution, add 1-(2-cyanoethyl)-2-phenylimidazole Then, a ruthenium salt is added to obtain a Ru-N precursor after reaction;

[0012] The Ru-N precursor is first annealed in an air atmosphere and then carbonized in a nitrogen atmosphere to obtain the catalyst.

[0013] Furthermore, the mass ratio of cyanamide, 1-(2-cyanoethyl)-2-phenylimidazole and ruthenium salt is (4-20):(0.5-5):(0.12-0.6), preferably 4:0.5:0.12.

[0014] Furthermore, the cyanamide includes dicyandiamide or melamine Dicyandiamide is preferred.

[0015] Furthermore, the ruthenium salt is ruthenium chloride (RuCl3, CAS No.: 10049-08-8) or a hydrate of ruthenium chloride, and the hydrate of ruthenium chloride is such as RuCl3·3H2O (CAS No.: 13815-94-6), preferably RuCl3.

[0016] Furthermore, the annealing treatment is: annealing the Ru—N precursor at 550° C. in an air atmosphere for 2-5 hours.

[0017] Furthermore, the carbonization treatment is: placing the annealed product in a nitrogen atmosphere and carbonizing it at 900° C. for 1-6 hours. For example, the carbonization time can be 1 hour, 2 hours, 3 hours, 4 hours, 5 hours or 6 hours.

[0018] Furthermore, the carbonization treatment time is 1-3h.

[0019] Furthermore, the carbonization treatment time is 3 hours.

[0020] The time of carbonization treatment affects the morphology of the catalyst and thus its performance. Specifically, in the present invention, as the carbonization time increases, Ru@NC can form a typical porous sheet carbon framework with abundant mesopores and macropores. This open structure can effectively promote the exposure of active sites and the mass transfer of reaction intermediates (such as adsorbed water (*H2O) and hydrogen (*H), etc.), thereby promoting reaction kinetics and alleviating large current polarization. When the carbonization time is short (such as when the carbonization time is 1h), Ru@NC presents a coexistence state with a certain number of large metal particles and small clusters (about 3.1 nanometers). When the time increases (such as when the carbonization time is 3h and 6h), the Ru@NC of 3h has a narrower size distribution and uniformly dispersed clusters than 6h, with an average size of about 2.2 nanometers. This may be because the clusters are more stable when encapsulated in the N-doped carbon layer, and the relatively small work function is more stable than large-sized nanoparticles. In addition, these thin layers ranging from about 3 to 7 layers help to accelerate the electron transfer from the metal core to the outer shell and enhance the metal-N interaction, which can well optimize the adsorption / desorption behavior of the reaction intermediates in HER and accelerate the reaction kinetics. With further extension of the carbonization time (such as when the carbonization time is 9 h), sharp agglomeration occurs due to the loss of the carbon protective layer, and no clusters are observed. In summary, 3 h is the optimal carbonization time.

[0021] Furthermore, the preparation method of the catalyst for regulating the electronic effect of Ru@NC core-shell heterogeneous interface to achieve efficient hydrogen evolution is:

[0022] First, 4 g of dicyandiamide (DCD) was dissolved in 60 ml of methanol to form a uniform solution, and 0.5 g of 1-(2-cyanoethyl)-2-phenylimidazole (CEPI) was added, and then 0.12 g of RuCl3 was added to obtain Ru@DCD-CEPI. In this process, the hydroxyl group (-OH) in methanol, the amino functional group (-NH2, -C=NH) and carbon-nitrogen triple bond (-C≡N) in DCD, and the carbon-nitrogen triple bond in CEPI reacted with the trivalent Ru with high-altitude orbitals. 3+ Under the interaction of hydrogen bonding, electrostatic attraction, etc., due to Ru 3+ Small size and minimal spatial resistance, forming a core Ru and shell DCD-CEPI molecular aggregate, namely Ru@DCD-CEPI; continued stirring for 48 hours, as the reaction time continued, methanol gradually evaporated, the concentration of Ru@DCD-CEPI increased, the intermolecular interaction was enhanced, and the -C≡N in the external DCD and the -C≡N in CEPI continued to promote the 1, 3 addition reaction to obtain -N=CN=C-, inducing the formation of nitrogen-doped polymer NC coated Ru core, obtaining Ru@NC complex, which is the Ru-N precursor;

[0023] The Ru-N precursor was then annealed at 550°C in air for 3 h to form a flaky structure; this is because the outer shell of the Ru@NC composite contains a large amount of DCD polymer, and DCD or its polymer presents a typical flaky graphitic carbon nitride (g-C3N4) structure at 550°C in air.

[0024] Finally, the external composite was carbonized at 900°C for 3h in a nitrogen atmosphere to form a nitrogen-doped dense carbon layer, which was coated on the Ru core to prepare a sheet-like multi-level porous Ru@NC catalyst. It should be emphasized that the g-C3N4 formed by conventional DCD or its polymers at 550°C in air calcination will be completely decomposed at temperatures above 650°C, while the present invention successfully enhanced the thermal stability to 900°C and replicated its sheet-like structure. This is because the present invention introduced CEPI during the DCD polymerization process to stabilize the molecular skeleton.

[0025] The third technical solution of the present invention:

[0026] The present invention also provides application of the catalyst in producing hydrogen by electrolyzing water.

[0027] Compared with the prior art, the present invention has the following advantages and technical effects:

[0028] The present invention optimizes the charge effect of the Ru-NC heterogeneous interface and the intrinsic activity of the Ru site by regulating the particle size of the internal Ru core and the nitrogen content of the outer shell, thereby promoting the improvement of the overall HER performance.

[0029] The electrochemical HER performance of the catalyst prepared in the present invention and the benchmark Pt / C was evaluated in a typical three-electrode system (Hg / HgO, graphite carbon rod, and catalyst as reference electrode, counter electrode, and working electrode, respectively) in 1.0 M KOH electrolyte. -2 The overpotential of Ru@NC-1h is only 48mV, which is lower than 58mV of Pt / C and 71mV of Ru@NC-1h, and much better than other samples with different carbonization times (>100mV). However, Ru@NC-1h only needs 389mV overpotential to drive 250mA·cm -2 The current density is much better than 489 mV of Pt / C and even the same as that of Ru@NC-6h. In addition, Ru@NC-3h has a high current density of 250 mA cm -2 and 500mA·cm -2 The overpotentials of Ru@NC-3h are 296 mV and 455 mV, respectively, showing a lower overpotential. In addition, the LSV curve of Ru@NC-3h remains almost unchanged before and after 3000 cyclic voltammetry (CV) tests, showing excellent durability. -2In the constant current test, the stable voltage output lasted for 24 hours without attenuation, further confirming the superior stability. Therefore, the present invention successfully prepared a highly efficient hydrogen evolution catalyst by regulating the electronic effect of the Ru@NC core-shell heterogeneous interface. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] The drawings constituting a part of the present application are used to provide a further understanding of the present application. The illustrative embodiments and descriptions of the present application are used to explain the present application and do not constitute an improper limitation on the present application. In the drawings:

[0031] Figure 1 The X-ray diffraction (XRD) results of the catalysts prepared at different carbonization times in Examples 1-3 and Comparative Example 1.

[0032] Figure 2 Field emission scanning electron microscope (SEM) images and transmission electron microscope (TEM) images of the catalysts prepared at different carbonization times in Examples 1-3 and Comparative Example 1, wherein ac are SEM images of Ru@NC-1h, Ru@NC-3h and Ru@NC-6h, respectively; df, hj, ln are TEM images of Ru@NC-1h, Ru@NC-3h and Ru@NC-6h, respectively; the illustrations in e, i and m are the corresponding cluster size distribution fitting curves; g, k, o, r are (002) crystal plane lattice spacing measurement diagrams of Ru@NC-1h, Ru@NC-3h, Ru@NC-6h and Ru@NC-9h, respectively; s is the energy dispersive spectrum (EDS) mapping image of Ru@NC-3h.

[0033] Figure 3 The particle size distribution of the catalysts prepared at different carbonization times in Examples 1-3;

[0034] Figure 4 High-resolution XPS Ru3p and N1s spectra of the catalysts prepared at different carbonization times in Examples 1-3 and Comparative Example 1, wherein a is the high-resolution XPS Ru 3p, b is the N1s spectrum, c is the mass percentage of elemental Ru based on XPS (purple), the mass percentage of N (gray), the Ru-N relative value (red) and the calculated value based on Ru-N (magenta), the Ru-N relative value represents the relative mass percentage of Ru-N in N1s, and the calculated value based on Ru-N is obtained by multiplying the Ru-N relative value by the N content.

[0035] Figure 5 The results of the hydrogen evolution performance test of the catalysts prepared at different carbonization times in Examples 1-3 and Comparative Example 1, (a) is the activity of the catalyst and the benchmark catalysts Pt / C and Ru / C, (b) is the stability of the catalyst in Example 1, and the inset in (b) is the chronoamperometric current of 500 mA cm-2 The stability test of the catalyst in Example 1 was carried out.

[0036] Figure 6 The Tafel data of the catalysts prepared at different carbonization times in Examples 1-3 and Comparative Example 1.

[0037] Figure 7 Activity data for the catalyst prepared in Example 4.

[0038] Figure 8 These are the activity data for the catalyst prepared in Example 5.

[0039] Fig. 9 These are the activity data for the catalyst prepared in Example 6.

[0040] Fig.10 These are the activity data for the catalyst prepared in Example 7.

[0041] Fig.11 These are the activity data for the catalyst prepared in Example 8. DETAILED DESCRIPTION

[0042] Various exemplary embodiments of the present invention will now be described in detail. This detailed description should not be considered as limiting the present invention, but should be understood as a more detailed description of certain aspects, features, and embodiments of the present invention.

[0043] It should be understood that the terms described in the present invention are only for describing special embodiments and are not intended to limit the present invention. In addition, for the numerical range in the present invention, it should be understood that each intermediate value between the upper and lower limits of the scope is also specifically disclosed. Each smaller range between the intermediate value in any stated value or stated range and any other stated value or intermediate value in the described range is also included in the present invention. The upper and lower limits of these smaller ranges can be independently included or excluded in the scope.

[0044] Unless otherwise indicated, all technical and scientific terms used herein have the same meanings as those generally understood by those skilled in the art. Although the present invention describes only preferred methods and materials, any methods and materials similar or equivalent to those described herein may also be used in the implementation or testing of the present invention. All documents mentioned in this specification are incorporated by reference to disclose and describe the methods and / or materials associated with the documents. In the event of a conflict with any incorporated document, the content of this specification shall prevail.

[0045] It will be apparent to those skilled in the art that various modifications and variations may be made to the specific embodiments of the present invention description without departing from the scope or spirit of the present invention. Other embodiments derived from the present invention description will be apparent to those skilled in the art. The present invention description and examples are exemplary only.

[0046] The words “include,” “including,” “have,” “contain,” etc. used in this document are open-ended terms, meaning including but not limited to.

[0047] All raw materials used in the embodiments of the present invention are purchased from the market. For example, RuCl3 is purchased from MacLean's reagent, CAS No.: 10049-08-8; RuCl3·3H2O is purchased from MacLean's reagent, CAS No.: 13815-94-6; dicyandiamide is purchased from MacLean's reagent, CAS No.: 461-58-5; 1-(2-cyanoethyl)-2-phenylimidazole is purchased from MacLean's reagent, CAS No.: 23996-12-5; melamine is purchased from MacLean's reagent, CAS No.: 108-78-1, item No.: M813390; methanol is purchased from MacLean's reagent, CAS No.: 67-56-1. The benchmark catalysts Pt / C and Ru / C were purchased from Johnson Matthey (Shanghai) Chemical Co., Ltd. and Chongqing Zuyanjia Technology Co., Ltd., respectively.

[0048] The technical solution of the present invention is further illustrated by the following embodiments.

[0049] Example 1

[0050] First, 4 g of DCD was dissolved in 60 ml of methanol to form a uniform solution, and 0.5 g of CEPI was added, and then 0.12 g of RuCl3 was added thereto to obtain Ru@DCD-CEPI. The solution was stirred for 48 h. As the reaction time continued, methanol gradually evaporated, the concentration of Ru@DCD-CEPI increased, and the intermolecular interaction was enhanced to obtain a Ru@NC complex (i.e., Ru-N precursor). Subsequently, the Ru-N precursor was annealed at 550 °C in an air atmosphere for 3 h to form a lamellar structure. Finally, it was carbonized at 900 °C in a nitrogen atmosphere for 3 h to form a nitrogen-doped dense carbon layer on the outside of the complex, which was coated on the Ru core to prepare a lamellar multi-level porous Ru@NC catalyst, recorded as Ru@NC-3h.

[0051] Example 2

[0052] The same as Example 1, except that the carbonization time at 900°C was 1 h, and the obtained catalyst was denoted as Ru@NC-1h.

[0053] Example 3

[0054] The same as Example 1, except that the carbonization time at 900°C is 6 h, and the obtained catalyst is denoted as Ru@NC-6h.

[0055] Example 4

[0056] First, 4 g of DCD was dissolved in 60 ml of methanol to form a uniform solution, and 0.5 g of CEPI was added, and then 0.12 g of RuCl3 was added thereto to obtain Ru@DCD-CEPI. The solution was stirred for 48 h. As the reaction time continued, methanol gradually evaporated, the concentration of Ru@DCD-CEPI increased, and the intermolecular interaction was enhanced to obtain a Ru@NC complex (i.e., Ru-N precursor). Subsequently, the Ru-N precursor was annealed at 550°C in an air atmosphere for 2 h to form a lamellar structure. Finally, it was carbonized at 900°C in a nitrogen atmosphere for 3 h to form a nitrogen-doped dense carbon layer on the outside of the complex, which was coated on the Ru core to prepare a lamellar multi-level porous Ru@NC catalyst.

[0057] Example 5

[0058] First, 4 g of DCD was dissolved in 60 ml of methanol to form a uniform solution, and 0.5 g of CEPI was added, and then 0.12 g of RuCl3 was added thereto to obtain Ru@DCD-CEPI. The solution was stirred for 48 h. As the reaction time continued, methanol gradually evaporated, the concentration of Ru@DCD-CEPI increased, and the intermolecular interaction was enhanced to obtain a Ru@NC complex (i.e., Ru-N precursor). Subsequently, the Ru-N precursor was annealed at 550°C in an air atmosphere for 5 h to form a lamellar structure. Finally, it was carbonized at 900°C in a nitrogen atmosphere for 3 h to form a nitrogen-doped dense carbon layer on the outside of the complex, which was coated on the Ru core to prepare a lamellar multi-level porous Ru@NC catalyst.

[0059] Example 6

[0060] Same as Example 1, except that DCD is replaced with an equal amount of melamine.

[0061] Example 7

[0062] Same as Example 1, except that RuCl3 is replaced by 0.16g RuCl3·3H2O.

[0063] Example 8

[0064] Same as Example 1, except that the added amount of DCD is 20 g, the added amount of CEPI is 5 g, and the added amount of RuCl3 is 0.6 g.

[0065] Comparative Example 1

[0066] The same as Example 1, except that the carbonization time at 900°C is 9 h, and the obtained catalyst is denoted as Ru@NC-9h.

[0067] Comparative Example 2

[0068] The same as Example 1, except that CEPI was not added when preparing the Ru@NC catalyst.

[0069] Since CEPI was not added in this comparative example, the flaky graphite carbon nitride (g-C3N4) structure generated at 550°C in air was decomposed at a carbonization temperature of 900°C, the catalyst performance was greatly reduced, and the catalyst yield was very low.

[0070] Comparative Example 3

[0071] Same as Example 1, except that CEPI is replaced by 2-methylimidazole.

[0072] Since the structure of 2-methylimidazole is Without the -C≡N in CEPI, there is no strong chemical reaction or strong chelating interaction with DCD. The flaky graphite carbon nitride (g-C3N4) generated at 550°C in air during the high-temperature carbonization process is still decomposed, causing Ru to agglomerate into large particles and greatly reducing the catalyst performance.

[0073] Comparative Example 4

[0074] Same as Example 1, except that methanol is replaced by water.

[0075] In this comparative example, methanol is replaced by the common solvent water (H2O). Although DCD can be dissolved in water to form a uniform solution, CEPI is not easily soluble in water, resulting in solid-liquid phase separation. At the same time, water is difficult to evaporate relative to methanol, the concentration of Ru@DCD-CEPI remains basically unchanged, the intermolecular interaction is weak, and the Ru@NC complex (i.e., Ru-N precursor) cannot be formed. During the high-temperature carbonization process, the flaky graphite carbon nitride (g-C3N4) generated at 550°C in air is still decomposed, resulting in the agglomeration of Ru into large particles, and the catalyst performance is greatly reduced.

[0076] Comparative Example 5

[0077] Same as Example 1, except that methanol is replaced by tetrahydrofuran (THF).

[0078] In this comparative example, methanol was replaced by the common organic solvent THF. Although CEPI can be dissolved in THF to form a uniform solution, DCD is not easily dissolved, resulting in solid-liquid phase separation. At the same time, tetrahydrofuran evaporates faster than methanol and has no -OH, so the intermolecular interaction is weak, which is not conducive to inducing the formation of Ru@NC complex (i.e., Ru-N precursor). During the high-temperature carbonization process, the flaky graphite carbon nitride (g-C3N4) generated at 550°C in air is still decomposed, resulting in the agglomeration of Ru into large particles, and the catalyst performance is greatly reduced.

[0079] The X-ray diffraction (XRD) results of the catalysts prepared at different carbonization times in Examples 1-3 and Comparative Example 1 are shown in Figure 1 .Depend on Figure 1 It can be seen that the five characteristic diffraction peaks at 38.4°, 42.2°, 44.0°, 58.3° and 69.4° are well assigned to the (100), (002), (101), (102) and (110) crystal planes of metallic hexagonal close-packed (hcp) Ru (hcp-Ru: PDF#06-0663), indicating that a series of Ru@NC electrocatalysts were successfully prepared. At the same time, the diffraction peaks of different intensities reveal Ru nanoclusters of different particle sizes.

[0080] Field emission scanning electron microscope (SEM) images and transmission electron microscope (TEM) images of the catalysts prepared at different carbonization times in Examples 1-3 and Comparative Example 1 are shown in Figure 2 The particle size distribution diagram of the catalyst prepared at different carbonization times in Example 1-3 is shown in Figure 3 It can be seen that Ru@NC-1h( Figure 2 a) and Ru@NC-3h( Figure 2 b) both show a typical porous sheet-like carbon framework with abundant mesopores and macropores. Even under strict carbonization conditions, Ru@NC-6h( Figure 2 c) also shows excellent structural retention. It is worth noting that this open structure can effectively promote the exposure of active sites and the mass transfer of reaction intermediates (such as adsorbed water (*H2O) and hydrogen (*H), thereby promoting reaction kinetics and alleviating high current polarization. According to TEM observations, Ru@NC-1h( Figure 3 (a) has a certain amount of coexistence of large metal particles and small clusters (about 3.1 nm). Paradoxically, with Ru@NC-6h( Figure 3 Compared with the average size of Ru@NC-3h (c) (about 2.5 nm), Figure 3 (b) has clusters with narrow size distribution and uniform dispersion, with an average size of about 2.2 nm. This may be because the clusters are wrapped in the N-doped carbon layer ( Figure 2 f, j and n) are more stable and have a relatively small work function than large-sized nanoparticles. In addition, these thin layers, ranging from about 3 to 7 layers, help accelerate the electron transfer from the metal core to the outer shell and enhance the metal-N interaction. This can well optimize the adsorption / desorption behavior of reaction intermediates in HER and accelerate the reaction kinetics. Figure 2 The pq in Figure 2 shows that sharp agglomeration was observed in Ru@NC-9h due to the loss of the carbon protective layer, and no clusters were observed. In addition, TEM ( Figure 2Obvious lattice fringes were observed in f, j, n, and q), and the corresponding d spacing ( Figure 2 g, k, o and r) is 0.214 nm, which is attributed to the hcp (002) crystal plane of Ru@NC-1h, Ru@NC-3h, Ru@NC-6h and Ru@NC-9h. In addition, energy dispersive X-ray spectroscopy (EDS, Figure 2 (s) demonstrates the uniform distribution of C, N, O, and Ru elements, indicating the formation of the expected Ru@NC-3h.

[0081] It should be noted that, generally, as the carbonization time increases (i.e., as the degree of carbonization increases), the metal particles become more and more agglomerated. The difference is that in the present invention, the particles agglomerate after 1 hour of carbonization, and the particles are uniform after 3 hours of carbonization; the particles are uniform but the particle size becomes larger after 6 hours of carbonization; and the particles agglomerate seriously after 9 hours of carbonization. This is because in the present invention, as the degree of carbonization increases, the Ru-NC heterostructure becomes more and more compact, the Ru-N interaction is enhanced, and its work function is smaller than that of Ru nanoparticles, inducing the anti-Oswald ripening process of the particles, that is, large particles migrate, decompose into small particles and clusters, and form a Ru-N structure. Moreover, the catalyst of the present invention can still basically maintain the heterostructure unchanged under carbonization at 900°C for 6 hours, which verifies that the present invention prepares an extremely stable Ru@NC core-shell heterostructure.

[0082] The high-resolution XPS Ru 3p and N1s spectra of the catalysts prepared at different carbonization times in Examples 1-3 and Comparative Example 1 are shown in Figure 4 .exist Figure 4 In a, a clear characteristic peak of high-resolution Ru 3p is located at 461.8eV, which is attributed to Ru 3p3 / 2 of Ru@NC-3h. The binding energy position (BEP) shifts positively by 0.27eV and 0.13eV in Ru@NC-1h and Ru@NC-6h, respectively, indicating that the charge is transferred outward. The high-resolution N1s can be split into five characteristic peaks in Ru@NC-1h / 3h / 6h ( Figure 4 b), corresponding to pyrrolic-N (397.4 eV), Ru-N (398.4 eV), pyridinic-N (399.3 eV), graphene (401.1 eV), and oxidized-N (402.8 eV), respectively. However, the Ru-N peak is missing in Ru@NC-9h due to the severe annealing conditions. In addition, the BEP of N in Ru@NC-3h is negatively shifted by 0.31 eV and 0.12 eV compared with Ru@NC-1h and Ru@NC-6h, respectively, confirming the enriched charge state. The maximum charge accumulation from Ru to N sites in Ru@NC-3h indicates a strong Ru-N interaction, consistent with a thin core-shell heterointerface that is conducive to charge transfer ( Figure 2j). The high surface Ru(N) contents determined by XPS range from 14.1(5.2), 14.3(6.0), 14.9(4.3) to 31.2(2.2) Wt% for Ru@NC-1h, Ru@NC-3h, Ru@NC-6h, and Ru@NC-9h, respectively. Figure 4 c). Taking into account the results of TEM, XRD and XPS, the present invention provides a catalyst for regulating the electronic effect of Ru@NC core-shell heterogeneous interface to achieve efficient hydrogen evolution, that is, regulating the charge effect of the heterojunction interface by adjusting the particle size of the internal Ru core and the nitrogen content of the outer shell.

[0083] In 1.0M KOH electrolyte, the electrochemical HER performance of the catalyst prepared in the present invention and the benchmark Pt / C was evaluated by a typical three-electrode system. The hydrogen evolution performance test results of the catalysts prepared at different carbonization times in Examples 1-3 and Comparative Example 1 are shown in Figure 5 .like Figure 5 As shown in (a), Ru@NC-3h at 10 mA cm -2 The overpotential of Ru@NC-1h is only 48 mV, which is lower than 58 mV of Pt / C and 71 mV of Ru@NC-1h, and much better than other samples with carbonization time (>100 mV). However, Ru@NC-1h takes 389 mV to provide 250 mA cm -2 , which is much better than the 489 mV of Pt / C and even the same as that of Ru@NC-6h. In addition, Ru@NC-3h has a -2 and 500mA·cm -2 The overpotentials of are 296mV and 455mV, respectively, showing a lower overpotential. Figure 5 As shown in (b), the LSV curve of Ru@NC-3h remains almost unchanged after 3000 cyclic voltammetry (CV) tests, showing excellent durability. -2 In the constant current test, the stable voltage output lasted for 24 hours, confirming its excellent stability. Therefore, the present invention successfully prepared a highly efficient hydrogen evolution catalyst by regulating the electronic effect of the Ru@NC core-shell heterogeneous interface.

[0084] The Tafel data of the catalysts prepared at different carbonization times in Examples 1-3 and Comparative Example 1 are shown in Figure 6 It can be seen that the Tafel slope of the catalyst Ru@NC-3h in Example 1 is 30 mV·dec -1 , compared with commercial Pt / C (30mV·dec -1), indicating that the HER process follows a typical Volmer-Tafel mechanism, that is, the rate-controlling step is the Tafel process, and the Tafel slope of the water dissociation step is 120 mV·dec -1 , proving that the catalyst prepared by the present invention has good water dissociation ability.

[0085] Figure 7 Activity data of the catalyst prepared in Example 4, Ru@NC at 10, 250, 500 mA·cm -2 The overpotentials at current densities of 51, 318, and 448 mV were respectively, and the catalytic performance was consistent with that of Examples 1-3.

[0086] Figure 8 The activity data of the catalyst prepared in Example 5 show that Ru@NC has a high activity at 10, 250, and 500 mA·cm -2 The overpotentials at current densities of 53, 305, and 498 mV were respectively, and the catalytic performance was consistent with that of Examples 1-3.

[0087] Fig. 9 The activity data of the catalyst prepared in Example 6 show that Ru@NC has a high activity at 10, 250, and 500 mA·cm -2 The overpotentials at current densities of 43, 310, and 497 mV were respectively, and the catalytic performance was consistent with that of Examples 1-3.

[0088] Fig.10 The activity data of the catalyst prepared in Example 7 show that Ru@NC has a high activity at 10, 250, and 500 mA·cm -2 The overpotentials at current densities of 50, 295, and 449 mV were respectively, and the catalytic performance was consistent with that of Examples 1-3.

[0089] Fig.11 The activity data of the catalyst prepared in Example 8 show that Ru@NC has a high activity at 10, 250, and 500 mA·cm -2 The overpotentials at current densities of 47, 308, and 465 mV were respectively, and the catalytic performance was consistent with that of Examples 1-3.

[0090] The above are only preferred specific implementations of the present application, but the protection scope of the present application is not limited thereto. Any changes or substitutions that can be easily thought of by a person skilled in the art within the technical scope disclosed in the present application should be included in the protection scope of the present application. Therefore, the protection scope of the present application should be based on the protection scope of the claims.

Claims

1. A method for preparing a catalyst for achieving efficient hydrogen evolution by regulating the electronic effect of Ru@NC core-shell heterogeneous interface, characterized in that: The following steps are involved: Dissolve cyanamide in methanol to form a uniform solution, add 1-(2-cyanoethyl)-2-phenylimidazole, and then add ruthenium salt to obtain a Ru-N precursor after reaction; The Ru-N precursor is first annealed in an air atmosphere, and then carbonized in a nitrogen atmosphere to obtain the catalyst; The carbonization treatment is as follows: placing the annealed product in a nitrogen atmosphere and carbonizing it at 900° C. for 1-6 hours; The catalyst is a core-shell heterogeneous structure in which metal Ru clusters are coated on a three-dimensional porous nitrogen-doped carbon layer.

2. The method for preparing a catalyst according to claim 1, characterized in that: The mass ratio of the cyanamide, 1-(2-cyanoethyl)-2-phenylimidazole and the ruthenium salt is (4-20):(0.5-5):(0.12-0.6).

3. The method for preparing the catalyst according to claim 2, characterized in that: The cyanamide includes dicyandiamide or melamine.

4. The method for preparing the catalyst according to claim 1, characterized in that: The annealing treatment is: annealing the Ru—N precursor at 550° C. in an air atmosphere for 2-5 hours.

5. The method for preparing the catalyst according to claim 1, characterized in that: The carbonization treatment time is 1-3h.

6. The method for preparing the catalyst according to claim 5, characterized in that: The carbonization treatment time is 3 hours.

7. Use of the catalyst prepared according to the method according to any one of claims 1 to 6 in hydrogen production by electrolysis of water.

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