Medium-entropy NiMoCoN catalyst and preparation method thereof

Abstract

The invention discloses a medium-entropy NiMoCoN catalyst and a preparation method thereof. The active component of the catalyst is NiMoCoN; wherein in the compound NiMoCoN, the atomic percent of each element is as follows: 23 to 31 at.% of Ni, 15 to 33 at.% of Mo, 26 to 48 at.% of Co and 10 to 19 at.% of N. The NiMoCoN catalyst disclosed by the invention has lower overpotential, lower Tafel slope, lower electrochemical impedance and long-term stability when being used as a water electrolysis hydrogen production catalyst; when the material is applied to alkaline liquid (1.0 M KOH), the hydrogen evolution overpotential under the current density of 10mA. Cm <-2 > can be as low as 94mV, and the material can stably work for more than 100 hours under the condition of 300mA. Cm <-2 >; in an acidic electrolyte (0.5 M H2SO4), the hydrogen evolution overpotential can be as low as 141mV under the current density of 10mA. Cm <-2 >, and the hydrogen evolution overpotential can stably work for more than 100 hours under the condition of 300mA. Cm <-2 >.

Description

Technical Field

[0001] The present invention relates to a medium-entropy NiMoCoN catalyst, and also relates to a preparation method of the above catalyst. Background Art

[0002] As a clean energy source, hydrogen is of great significance in energy transformation and reducing greenhouse gas emissions. Among the methods for producing hydrogen, water electrolysis for hydrogen production is considered an ideal green hydrogen production technology, and its reaction process involves the hydrogen evolution reaction (HER). In the process of the hydrogen evolution reaction, the selection of the catalyst has an important impact on the efficiency and economy of water electrolysis for hydrogen production.

[0003] Currently, water electrolysis hydrogen production catalysts are mainly divided into two categories: noble metal catalysts and non-noble metal catalysts. Noble metal catalysts, such as platinum (Pt), are widely used due to their excellent catalytic performance. However, due to the scarcity of their raw materials and high prices, their popularization in large-scale applications is limited. Non-noble metal catalysts have received extensive attention due to their rich sources and low costs. However, non-noble metal catalysts have problems such as unstable material structures, decreased catalytic performance, and short lifetimes in strong alkali or strong acid electrolytic water environments, and these problems are particularly serious in strong acid environments. Therefore, finding a catalyst that is non-noble metal and can have high efficiency and high stability under strong acid and strong base conditions has become a research hotspot.

[0004] In recent years, transition metal nitride materials have received the attention of researchers due to their good catalytic performance, excellent stability, and low costs. As a potential catalytic material, Ni3N has a special electronic structure and performs well in the hydrogen evolution reaction, becoming one of the research hotspots. However, although Ni3N has better stability than non-noble metal catalysts in acid-base environments, there is still a large gap in the catalytic performance of Ni3N compared to non-noble metal catalysts. Summary of the Invention

[0005] Object of the Invention: The object of the present invention is to provide a NiMoCoN catalyst with high stability, high catalytic activity and can be used for water electrolysis hydrogen production in acidic and alkaline solutions; another object of the present invention is to provide a preparation method of the above NiMoCoN catalyst.

[0006] Technical Solution: For the medium-entropy NiMoCoN catalyst described in the present invention, the active ingredient of the catalyst is NiMoCoN; wherein, in the compound NiMoCoN, the atomic percentages of each element are: Ni 23-31 at.%, Mo 15-33 at.%, Co 26-48 at.%, N 10-19 at.%.

[0007] Among them, the grain size of the NiMoCoN is 10 to 100 nm, presenting a cellular particle shape.

[0008] The compound NiMoCoN is mainly the hexagonal Ni3N phase, accompanied by a small amount of the orthorhombic Co2N phase and the tetragonal Mo2N phase; the Ni, Mo, and Co elements are dissolved in the above phases in a substitutional or interstitial form.

[0009] Among them, the catalyst includes a conductive substrate and NiMoCoN supported on the conductive substrate; NiMoCoN is supported on the conductive substrate in the form of a thin film, which is obtained by magnetron sputtering, electrodeposition + nitridation process, molten salt method, or solvothermal method.

[0010] The conductive substrate is a metal sheet or a porous metal sheet of Ni, Ti, Cu, Ta, Fe, Co, Mo, or W.

[0011] For the preparation method of the above catalyst, NiMoCoN is supported on the conductive substrate by magnetron sputtering, and the specific steps are as follows:

[0012] (1) Fix the cleaned conductive substrate on the magnetron sputtering instrument stage and evacuate to below 6×10 -4 Pa.

[0013] (2) Introduce Ar gas and pre-sputter at a power density of 1 to 9 W / cm -2 to clean the NiCoMo alloy target.

[0014] (3) Introduce a mixed gas of Ar and N2, maintain the power density at 1 to 9 W / cm -2 , and the deposition time is 10 to 100 minutes to obtain NiMoCoN on the conductive substrate.

[0015] Among them, in step (1), the conductive substrate is ultrasonically cleaned in acetone, ethanol, and deionized water in sequence.

[0016] In step (2), the pre-sputtering time is 10 to 15 min.

[0017] In step (3), the gas flow ratio of Ar and N2 is 3:1 to 6:1; in the obtained catalyst, the loading amount of NiMoCoN on the conductive substrate is 0.2 to 5 mg / cm 2 .

[0018] In step (3), during the magnetron sputtering deposition preparation process, a DC power supply, RF power supply, MF power supply, DC pulse power supply, or high-energy pulse power supply can be used, and the working gas pressure is 0.2 to 5 Pa.

[0019] The method for preparing the NiMoCoN catalyst on a conductive substrate is not limited to the magnetron sputtering technique, and other existing techniques can also be used, such as: (1) electro-depositing to obtain a NiMoCo alloy metal and then nitriding it in an ammonia atmosphere; (2) the molten salt method; (3) the solvothermal method for synthesis.

[0020] The catalyst can also include a porous support and NiMoCoN nanopowders loaded on the porous support. Weigh the raw materials corresponding to each element in the chemical formula according to the stoichiometric ratio, mix them, and use the existing powder preparation process to obtain NiMoCoN nanopowders. Then, load the nanopowders on the porous support using techniques such as the impregnation method.

[0021] The catalyst obtained by loading NiMoCoN on a conductive substrate using the magnetron sputtering method in the present invention, when applied in an alkaline liquid (1.0 M KOH), the hydrogen evolution overpotential at a current density of 10 mA·cm-2 can be as low as 94 mV, and it can stably operate for more than 100 hours under the condition of 300 mA·cm-2; in an acidic electrolyte (0.5 M H2SO4), the hydrogen evolution overpotential at a current density of 10 mA·cm-2 can be as low as 141 mV, and it can stably operate for more than 100 hours under the condition of 300 mA·cm-2; the Tafel slopes of the catalyst are respectively: as low as 100 mV / dec under alkaline conditions and as low as 92 mV / dec under acidic conditions; the electrochemical impedance Rct under alkaline and acidic conditions can be as low as 4 Ω and 1 Ω respectively.

[0022] Beneficial effects: Compared with the prior art, the present invention has the following remarkable effects:

[0023] (1) When the NiMoCoN catalyst of the present invention is used as an electrolytic water hydrogen production catalyst, it has a lower overpotential, a lower Tafel slope, a lower electrochemical impedance, and long-term stability; compared with noble metal catalysts, the raw materials of the NiMoCoN catalyst of the present invention are rich in sources and the preparation cost is lower; at the same time, compared with non-noble metal catalysts, the catalyst of the present invention has good stability and can be used for electrolytic water hydrogen production in acidic and alkaline solutions.

[0024] (2) Compared with the Ni3N nitride thin film catalyst, the NiMoCoN thin film catalyst of the present invention has higher catalytic activity. When the Ni3N thin film catalyst is used as a HER electrode in an alkaline (1.0 M KOH) electrolyte, Ni3N can exhibit an overpotential of 134 mV at a current density of 10 mA·cm-2, while the NiMoCoN thin film catalyst can exhibit a minimum overpotential of 94 mV, and at 300 mA·cm -2The voltage remains stable without significant decline during long-term electrolysis for 100 h at a current density. Similarly, when the Ni3N thin-film catalyst is used as the HER electrode in an acidic (0.5 M H2SO4) electrolyte, an overpotential of 196 mV can be exhibited at a current density of 10 mA·cm-2, while the NiMoCoN thin-film shows a minimum overpotential of 92 mV and at 300 mA·cm -2 The voltage remains stable without significant decline during long-term electrolysis for 100 h at a current density. Description of the Drawings

[0025] Figure 1 Energy spectrum of NiMoCoN prepared in Example 1;

[0026] Figure 2 Surface morphology of NiMoCoN prepared in Example 1;

[0027] Figure 3 Linear sweep voltammogram of NiMoCoN catalysts with different compositions under alkaline conditions (1 M KOH);

[0028] Figure 4 Linear sweep voltammogram of NiMoCoN catalysts with different compositions under acidic conditions (0.5 M H2SO4);

[0029] Figure 5 Tafel slope diagram of NiMoCoN catalysts with different compositions under alkaline conditions (1 M KOH);

[0030] Figure 6 Tafel slope diagram of NiMoCoN catalysts with different compositions under acidic conditions (0.5 M H2SO4);

[0031] Figure 7 Electrochemical impedance spectroscopy diagram of NiMoCoN catalysts with different compositions under alkaline conditions (1 M KOH);

[0032] Figure 8 Electrochemical impedance spectroscopy diagram of NiMoCoN catalysts with different compositions under acidic conditions (0.5 M H2SO4);

[0033] Figure 9 Stability curve of the NiMoCoN catalyst prepared in Example 1 in 1 M KOH;

[0034] Figure 10 Energy spectrum of NiMoCoN prepared in Example 2;

[0035] Figure 11 Surface morphology of NiMoCoN prepared in Example 2;

[0036] Figure 12 The stability curve of NiMoCoN prepared in Example 2 in 0.5 M H2SO4;

[0037] Figure 13 The energy spectrum diagram of NiMoCoN prepared in Example 3;

[0038] Figure 14 The surface morphology diagram of NiMoCoN prepared in Example 3;

[0039] Figure 15 The surface morphology diagram of NiMoCoN prepared in Example 4;

[0040] Figure 16 The surface morphology diagram of NiMoCoN prepared in Example 5;

[0041] Figure 17 The surface morphology diagram of NiMoCoN prepared in Example 6.

[0042] Figure 18 The energy spectrum diagram of NiN prepared in Comparative Example 1;

[0043] Figure 19 The surface morphology diagram of NiN prepared in Comparative Example 1;

[0044] Figure 20 The linear sweep voltammogram of the NiN catalyst prepared in Comparative Example 1 under alkaline conditions (1 M KOH);

[0045] Figure 21 The linear sweep voltammogram of the NiN catalyst prepared in Comparative Example 1 under acidic conditions (0.5 M H2SO4);

[0046] Figure 22 The Tafel slope diagram of the NiN catalyst prepared in Comparative Example 1 under alkaline conditions (1 M KOH);

[0047] Figure 23 The Tafel slope diagram of the NiN catalyst prepared in Comparative Example 1 under acidic conditions (0.5 M H2SO4);

[0048] Figure 24 The electrochemical impedance spectroscopy diagram of the NiN catalyst prepared in Comparative Example 1 under alkaline conditions (1 M KOH);

[0049] Figure 25 The electrochemical impedance spectroscopy diagram of the NiN catalyst prepared in Comparative Example 1 under acidic conditions (0.5 M H2SO4). Detailed implementation manners

[0050] Example 1

[0051] The preparation method of the catalyst of the present invention uses magnetron sputtering to load NiMoCoN on the conductive substrate Ti sheet, and specifically includes the following steps:

[0052] (1) Select a Ti sheet with a size of 1 cm × 2 cm as the conductive substrate, and ultrasonically clean it in acetone, absolute ethanol and deionized water in turn, with each part being cleaned for 15 minutes; after cleaning, dry it in a vacuum drying oven at 60 °C for 30 minutes for later use;

[0053] (2) Install the Ni 23 Mo 33 Co 27 (the subscript is the atomic percentage at.%, the same hereinafter) alloy target on the target table, fix the cleaned Ti sheet substrate on the sample table and place it on the water-cooled table of the cavity. After closing the cavity, turn on the mechanical pump and molecular pump in turn, and pump the cavity pressure to below 6×10 -4 Pa;

[0054] (3) Introduce 20 sccm Ar, maintain the gas pressure in the cavity at 0.5 Pa, set the DC power supply to 150 W, and the current density to 3 W / cm -2 , and pre-sputter for 10 minutes;

[0055] (4) After the surface cleaning of the target material is completed, maintain the gas pressure in the cavity at 0.5 Pa, set the DC power supply to 150 W, and the current density to 3 W / cm -2 , introduce Ar gas with a flow rate of 16 sccm and N2 gas with a flow rate of 4 sccm, the working pressure is 0.5 Pa, and the deposition time is 50 minutes.

[0056] The NiMoCoN prepared in Example 1 was analyzed by energy dispersive spectroscopy (such as Figure 1 ), and the Ni, Mo, Co and N components were 23 at%, 33 at%, 27 at% and 18 at% respectively. It was observed by scanning electron microscopy (such as Figure 2 ), that NiMoCoN has a flat and dense nanostructure, the particle size is about 10 - 15 nm, and it has a cellular structure. The loading amount of the deposited sample on the Ti sheet substrate is 2.1 mg / cm -2 ; when the NiMoCoN of Example 1 was used as an electrolytic water hydrogen production catalyst, through electrochemical testing, it was obtained that the overpotential of HER under alkaline conditions at a current density of 10 mA / cm- 2 was 94 mV (such as Figure 3 b), the overpotential of HER under acidic conditions was 187 mV (such as Figure 4 b), its HER Tafel slope under alkaline conditions was 103 mV / dec -1 (such as Figure 5 b), and the HER Tafel slope under acidic conditions was 112 mV / dec-1 (as Figure 6 b), the electrochemical impedance is 4.9 Ω (alkaline condition, such as Figure 7 b), 2.5 Ω (acidic condition, such as Figure 8 b), indicating that the NiMoCoN catalyst obtained in Example 1 has high HER catalytic activity under both alkaline or acidic solution conditions. The NiMoCoN of Example 1 has a long-term stability of more than 100 hours at a large current density of 300 mA·cm -2 in an alkaline environment (such as Figure 9 ).

[0057] Example 2

[0058] Example 2 has the same preparation method as Example 1, and the only difference is that: in step (2) of Example 2, a Ni 26 Mo 15 Co 48 alloy target is used, and the other conditions remain unchanged.

[0059] The NiMoCoN prepared in Example 2 is analyzed by energy dispersive spectroscopy (such as Figure 10 ), and the contents of Ni, Mo, Co and N are 26 at%, 15 at%, 48 at% and 11 at% respectively; through scanning electron microscope observation (such as Figure 11 ), the NiMoCoN structure has a flat and dense nanostructure, the particle size is about 10 - 15 nm, and it has a cellular structure. The loading amount of the deposited sample on the Ti sheet substrate is 2.2 mg·cm -2 . When the NiMoCoN of Example 2 is used as an electrolytic water hydrogen production catalyst, through electrochemical testing, the HER overpotential under alkaline conditions at 10 mA·cm- 2 is 109 mV (such as Figure 3 c), the HER overpotential under acidic conditions is 141 mV (such as Figure 4 c); the HER Tafel slope under alkaline conditions is 109 mV / dec (such as Figure 5 c), the HER Tafel slope under acidic conditions is 92 mV / dec (such as Figure 6 c); the electrochemical impedance (such as Figure 7 c and 8c) is 8.5 Ω (alkaline) and 1.5 Ω (acidic). The NiMoCoN catalyst obtained in Example 2 has high HER catalytic activity under both alkaline or acidic solution conditions.

[0060] The NiMoCoN of Example 2 has a long-term stability of more than 100 hours at a large current density of 300 mA·cm -2 in an acidic environment (such as Figure 12 ).

[0061] Example 3

[0062] Example 3 was prepared in the same manner as Example 1, with the only difference being that in step (2) of Example 3, Ni 28 Mo 26 Co 34 alloy target was used, and the other conditions remained unchanged.

[0063] The NiMoCoN prepared in Example 3 was analyzed by energy dispersive spectroscopy (such as Figure 13 ), and the contents of Ni, Mo, Co, and N were 28 at%, 26 at%, 34 at%, and 12 at% respectively; by scanning electron microscope observation (such as Figure 14 ), the NiMoCoN structure had a flat and dense nanostructure, the average particle size was about 20 - 50 nm, and it showed a cellular structure. The loading amount of the deposited sample on the Ti sheet substrate was 2.3 mg·cm -2 . When the NiMoCoN of Example 3 was used as an electrolytic water hydrogen production catalyst, through electrochemical testing, the overpotential of HER under alkaline conditions at 10 mA·cm- 2 was 117 mV (such as Figure 3 b), and the overpotential of HER under acidic conditions was 142 mV (such as Figure 4 b); the Tafel slope of HER under alkaline conditions was 122 mV / dec (such as Figure 5 b), and the Tafel slope of HER under acidic conditions was 92 mV / dec (such as Figure 6 b); the electrochemical impedance (such as Figure 7 b and 8c) was 6 Ω (alkaline) and 2.2 Ω (acidic). It shows that the NiMoCoN catalyst prepared in Example 3 has high HER catalytic activity under both alkaline or acidic solution conditions.

[0064] Example 4

[0065] Example 4 was prepared in the same manner as Example 1, with the only difference being that in step (2) of Example 4, Ni 27 Mo 18 Co 43 alloy target was used, and the other conditions remained unchanged.

[0066] The NiMoCoN prepared in Example 4 was analyzed by energy dispersive spectroscopy, and the contents of Ni, Mo, Co, and N were 28 at%, 18 at%, 43 at%, and 11 at% respectively; by scanning electron microscope observation (such as Figure 15 ), the NiMoCoN structure had a flat and dense nanostructure, the particle size was about 10 - 40 nm, and it showed a cellular structure. The loading amount of the deposited sample on the Ti sheet substrate was 2.3 mg·cm -2When the NiMoCoN of Example 4 is used as an electrolytic water hydrogen production catalyst, through electrochemical testing, it is obtained that the overpotential of alkaline HER is 133 mV at 10 mA·cm- 2 under the following conditions (as shown in Figure 3 b), and the overpotential of acidic HER is 170 mV (as shown in Figure 4 b); the Tafel slope of alkaline HER is 120 mV / dec (as shown in Figure 5 b), and the Tafel slope of acidic HER is 109 mV / dec (as shown in Figure 6 b); the electrochemical impedance (as shown in Figure 7 b and 8b) is 8.5 Ω (alkaline) and 1.4 Ω (acidic), indicating that the NiMoCoN prepared in Example 4 has high HER catalytic activity under both alkaline or acidic solution conditions.

[0067] Example 5

[0068] The preparation method of the catalyst of the present invention uses magnetron sputtering to load NiMoCoN on a conductive substrate Ti sheet, and specifically includes the following steps:

[0069] (1) Select a Ti sheet with a size of 1 cm × 2 cm as the conductive substrate, and ultrasonically clean it in acetone, absolute ethanol, and deionized water in sequence, with each part being cleaned for 15 minutes; after cleaning, dry it in a vacuum drying oven at 60 °C for 30 minutes for standby;

[0070] (2) Install the Ni 23 Mo 32 Co 27 alloy target on the target table, fix the cleaned Ti sheet on the sample table and place it on the water-cooled table in the cavity. After closing the cavity, turn on the mechanical pump and molecular pump in sequence, and pump the cavity pressure to below 6×10 -4 Pa;

[0071] (3) Introduce 20 sccm Ar, maintain the gas pressure in the cavity at 0.5 Pa, set the DC power supply to 150 W, and the current density to 3 Wcm -2 , and pre-sputter for 10 min;

[0072] (4) After the surface cleaning of the target is completed, maintain the gas pressure in the cavity at 0.5 Pa, set the RF power supply to 30 W, and the current density to 1 Wcm -2 , introduce Ar with a gas flow rate of 24 sccm and N2 with a gas flow rate of 4 sccm, the working pressure is 5 Pa, and the deposition time is 10 min.

[0073] The NiMoCoN prepared in Example 5 is obtained by energy dispersive spectroscopy analysis, and the components of Ni, Mo, Co, and N are 23 at%, 32 at%, 27 at%, and 18 at% respectively; through scanning electron microscope observation (as shown inFigure 16 ), the NiMoCoN structure has a flat and dense nanostructure with a particle size of about 10 - 15 nm, presenting a cellular structure. The loading amount of the deposited sample on the Ti substrate is 0.2 mg·cm -2 . When the NiMoCoN of Example 5 is used as an electrolytic water hydrogen production catalyst, through electrochemical tests, it is obtained that the overpotential of HER under alkaline conditions at 10 mA·cm- 2 is 117 mV (as Figure 3 c), and the overpotential of HER under acidic conditions is 191 mV (as Figure 4 c); the Tafel slope of HER under alkaline conditions is 105 mV·dec -1 (as Figure 5 c), and the Tafel slope of HER under acidic conditions is 115 mV·dec -1 (as Figure 6 c); the electrochemical impedance (as Figure 7 c and 8c) is 6.4 Ω (alkaline) and 2.5 Ω (acidic), indicating that the NiMoCoN prepared in Example 5 has high HER catalytic activity under both alkaline or acidic solution conditions.

[0074] Example 6

[0075] The preparation method of the catalyst of the present invention uses magnetron sputtering to load NiMoCoN on the conductive substrate Ti sheet, and specifically includes the following steps:

[0076] (1) Select a Ti sheet with a size of 1 cm × 2 cm as the conductive substrate, and ultrasonically clean it in acetone, absolute ethanol, and deionized water in sequence, with each part being cleaned for 15 minutes; after cleaning, dry it in a vacuum drying oven at 60 °C for 30 minutes for standby;

[0077] (2) Install the Ni 28 Mo 23 Co 36 alloy target on the target table, fix the cleaned Ti sheet on the sample table and place it on the water-cooled table of the cavity. After closing the cavity, turn on the mechanical pump and molecular pump in sequence, and pump the cavity pressure to below 6×10 -4 Pa;

[0078] (3) Introduce 20 sccm Ar, maintain the gas pressure in the cavity at 0.5 Pa, set the DC power supply to 150 W, and the current density to 3 Wcm -2 , and pre-sputter for 10 min;

[0079] (4) After the surface cleaning of the target is completed, maintain the gas pressure in the cavity at 0.5 Pa, set the high-energy pulsed power supply to 450 W, and the current density to 9 Wcm -2, the gas flow rate of Ar is 24 sccm, the gas flow rate of N2 is 8 sccm, the working pressure is 0.2 Pa, and the deposition time is 100 min.

[0080] The NiMoCoN prepared in Example 6 was obtained by energy dispersive spectroscopy analysis, and the Ni, Mo, Co, and N components were 28 at%, 23 at%, 36 at%, and 12 at%, respectively; by observing with a scanning electron microscope (as Figure 17 ), the NiMoCoN structure has a flat and dense nanostructure, the particle size is about 80 - 100 nm, and it has a cellular structure. The loading amount of the deposited sample on the Ti sheet substrate is 5 mg·cm -2 . When the NiMoCoN of Example 6 was used as an electrolytic water hydrogen production catalyst, through electrochemical testing, the HER overpotential under alkaline conditions at 10 mA·cm- 2 was 110 mV (as Figure 3 a), and the HER overpotential under acidic conditions was 168 mV (as Figure 4 a); the HER Tafel slope under alkaline conditions was 126 mV / dec (as Figure 5 a), and the HER Tafel slope under acidic conditions was 102 mV / dec (as Figure 6 a); the electrochemical impedance (as Figure 7 a and 8a) was 5.1 Ω (alkaline) and 2 Ω (acidic), indicating that the NiMoCoN prepared in Example 6 has high HER catalytic activity under both alkaline or acidic solution conditions.

[0081] Example 7

[0082] Example 7 is the same as Example 1, except that in step (2), Ni 23 Mo 33 Co 26 , Ni 24 Mo 30 Co 28 , Ni 26 Mo 29 Co 30 , Ni 27 Mo 27 Co 33 , Ni 26 Mo 18 Co 43 , Ni 25 Mo 16 Co 47 , Ni 25 Mo 31 Co 29 , Ni 26 Mo 30 Co 30 , Ni29 Mo 22 Co 37 、Ni 25 Mo 16 Co 47 、Ni 24 Mo 32 Co 28 、Ni 26 Mo 31 Co 29 、Ni 29 Mo 26 Co 34 、Ni 31 Mo 21 Co 39 、Ni 28 Mo 17 Co 43 Alloy targets are used to prepare catalytic materials.

[0083] As shown in Table 1, the corresponding compositions of the series of NiMoCoN prepared in Example 7 were obtained by energy dispersive spectroscopy analysis. According to Figures 3 - 8 , summarizing the corresponding performance test data in Table 1 shows that when it is used as an electrolysis water hydrogen production catalyst, the overpotential of HER under alkaline conditions at 10 mA·cm− 2 is in the range of 104-147 mV, and the overpotential of HER under acidic conditions is in the range of 147-200 mV; the Tafel slope of HER under alkaline conditions is in the range of 100-142 mV / dec, and the Tafel slope of HER under acidic conditions is in the range of 93-120 mV / dec; the electrochemical impedance is in the range of 5-11 Ω under alkaline conditions and in the range of 2-3 Ω under acidic conditions. The series of NiMoCoN prepared in Example 7 has high HER catalytic activity under alkaline or acidic solution conditions.

[0084] Table 1 shows the performance of the NiMoCoN catalyst obtained in Example 7

[0085]

[0086] Comparative Example 1

[0087] Comparative Example 1 is the same as Example 1, and the only difference is that an Ni alloy target is used in step (2), and the other conditions remain unchanged.

[0088] The NiN prepared in Comparative Example 1 was analyzed by energy dispersive spectroscopy (as Figure 18 ), and it was found that the Ni content was 87 at%, and the N content was 13 at%. Observed by scanning electron microscopy (as Figure 19 ), NiN has a loose and porous nanostructure, the particle size is about 50-200 nm, and it has a cubic particle structure. The loading amount on the deposited sample substrate is 2.1 mg·cm-2 ; When applying NiN of Comparative Example 1 as an electrolytic water hydrogen production catalyst, through electrochemical tests, it is obtained that under alkaline conditions, the overpotential of HER at a current density of 10 mA·cm- 2 is 238 mV (as shown in Figure 20 ), and under acidic conditions, the overpotential of HER is 336 mV (as shown in Figure 21 ). Its Tafel slope of HER under alkaline conditions is 112 mV·dec -1 (as shown in Figure 22 ), and the Tafel slope of HER under acidic conditions is 153 mV·dec -1 (as shown in Figure 23 ). The electrochemical impedances are 14 Ω (under alkaline conditions, as shown in Figure 24 ) and 3 Ω (under acidic conditions, as shown in Figure 25 ). Compared with Comparative Example 1, the NiMoCoN catalyst of the present invention has higher HER catalytic activity (lower overpotential, lower Tafel slope, and lower electrochemical impedance) under both alkaline or acidic solution conditions. The reason for the enhanced activity may be that the alloying of Mo and Co leads to a change in the internal electronic energy band structure of the Ni3N phase. At the same time, the alloying of Mo and Co promotes the refinement of grains and changes the atomic structure state on the grain surface.

[0089] Table 2 shows the performance of the NiN catalyst obtained in Comparative Example 1

[0090]

Claims

1. A medium-entropy NiMoCoN catalyst, characterized in that: The active component of the catalyst is NiMoCoN; among them, in the compound NiMoCoN, the atomic percentages of each element are: Ni 23-31 at.%, Mo 15-33 at.%, Co 26-48 at.%, N 10-19 at.%.

2. The medium-entropy NiMoCoN catalyst according to claim 1, wherein: The grain size of the NiMoCoN is 10-100 nm, presenting a cellular particle shape.

3. The medium-entropy NiMoCoN catalyst according to claim 1, wherein: The catalyst includes a conductive substrate and NiMoCoN supported on the conductive substrate.

4. The medium-entropy NiMoCoN catalyst according to claim 3, wherein: The conductive substrate is a metal sheet or a porous metal sheet of Ni, Ti, Cu, Ta, Fe, Co, Mo or W.

5. The medium-entropy NiMoCoN catalyst according to claim 1, wherein: The catalyst includes a porous carrier and NiMoCoN nanopowder supported on the porous carrier.

6. The preparation method of the catalyst according to claim 3, characterized in that, The NiMoCoN is supported on the conductive substrate by magnetron sputtering, specifically including the following steps: (1) Fix the cleaned conductive substrate on the magnetron sputtering instrument table and evacuate to below 6×10 -4 Pa; (2) Introduce Ar gas and pre-sputter at a power density of 1-9 W / cm -2 to clean the NiCoMo alloy target; (3) Introduce a mixed gas of Ar and N2, and maintain the power density at 1-9 W / cm -2 , with a deposition time of 10-100 minutes, to obtain NiMoCoN on the conductive substrate.

7. The preparation method according to claim 6, characterized in that: In step (2), the pre-sputtering time is 10-15 min.

8. The preparation method according to claim 6, characterized in that: In step (3), the gas flow ratio of Ar to N2 is 3:1-6:

1.

9. The preparation method according to claim 6, wherein: In step (3), during the magnetron sputtering deposition process, a DC power supply, an RF power supply, an MF power supply, a DC pulsed power supply or a high-energy pulsed power supply is used, and the working gas pressure is 0.2-5 Pa.

10. The preparation method according to claim 6, characterized in that: In step (3), in the obtained catalyst, the loading amount of NiMoCoN on the conductive substrate is 0.2 to 5 mg / cm 2 .

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