A high-density heterogeneous interface catalyst, a preparation method and application thereof

Abstract

The application discloses a high-density heterogeneous interface catalyst, and the catalyst comprises a Ni substrate and Ag / NiCoMoN nanosheet structures in-situ grown on the surface of the Ni substrate, wherein Ag is in a crystalline state, and NiCoMoN is in an amorphous state; the application further discloses a preparation method of the high-density heterogeneous interface catalyst, and the preparation method comprises the following steps: 1, immersing the Ni substrate into a hydrothermal reaction solution, and performing a hydrothermal reaction at 120 DEG C to 180 DEG C; 2, performing nitridation in an NH3 atmosphere and at 300 DEG C to 450 DEG C; meanwhile, the application discloses the application of the high-density heterogeneous interface catalyst. The catalyst has uniformly distributed crystalline Ag and amorphous NiCoMoN heterogeneous structures, forms a high-density crystalline-amorphous heterogeneous active interface, and exhibits excellent bifunctional catalytic performance in an alkaline seawater system, can simultaneously and efficiently catalyze a hydrogen evolution reaction and a hydrazine oxidation reaction, and is suitable for the technical field of electrocatalytic materials.

Description

Technical Field

[0001] This invention belongs to the field of electrocatalytic materials technology, and in particular relates to a high-density heterogeneous interface catalyst, its preparation method and application. Background Technology

[0002] Electrolysis of water for hydrogen production has become an important technological means due to its green process, pure products, and high compatibility with renewable energy sources. However, traditional water electrolysis systems typically rely on high-purity water as the reaction feedstock, which is limited by the scarcity and high cost of pure water resources, hindering large-scale application. Compared to pure water, seawater is abundant and easily accessible, offering significant economic and environmental advantages as an electrolysis feedstock, thus attracting widespread attention. However, seawater contains a large amount of chloride ions, which easily lead to a side reaction—chlorine evolution reaction (ClER)—at the high potential of the anode. This not only severely corrodes the anode material but also reduces system selectivity and efficiency, limiting its practical application. Furthermore, the complex electrolysis environment exacerbates catalyst deactivation, making it difficult to meet the requirements for long-term stable operation.

[0003] To address the aforementioned issues, researchers have recently proposed replacing the traditional oxygen evolution reaction (OER) or chlorine evolution reaction (ClER) with a low-potential hydrazine oxidation reaction (HzOR) to construct a "HzOR-HER" coupled hybrid seawater electrolysis (HSE) system. Compared to OER and ClER, HzOR has a lower reaction overpotential, which can significantly reduce system energy consumption while avoiding the generation of toxic chlorine gas, thus significantly improving the system's energy efficiency and environmental friendliness. This strategy provides a new approach for efficient and sustainable seawater electrolysis hydrogen production.

[0004] Transition metal nitrides (TMNs) are considered highly promising non-noble metal electrocatalysts due to their excellent conductivity, good chemical stability, and cost advantages. However, traditional TMNs still face problems such as insufficient catalytic activity and limited exposure of active sites in practical applications, which severely limit their electrocatalytic performance. Although some studies have attempted to enhance interfacial electron transport efficiency by constructing heterostructures, the complex synthesis processes often result in low density and uneven distribution of the heterostructure interface, making it difficult to achieve both high activity and long-term stability, and thus failing to meet the application requirements in harsh environments such as seawater electrolysis. Summary of the Invention

[0005] The purpose of this invention is to overcome the shortcomings of the prior art and provide a high-density heterostructure catalyst. This catalyst has a uniformly distributed crystalline Ag and amorphous NiCoMoN heterostructure, forming a high-density crystalline-amorphous heterostructure active interface. It exhibits excellent bifunctional catalytic performance in alkaline seawater systems, simultaneously and efficiently catalyzing both hydrogen evolution reaction and hydrazine oxidation reaction, thus solving the problems of insufficient catalytic activity and limited exposure of active sites in existing transition metal nitrides.

[0006] To achieve the above objectives, the technical solution adopted by the present invention is: a high-density heterogeneous interface catalyst, characterized in that the catalyst comprises a Ni substrate and an Ag / NiCoMoN nanosheet structure grown in situ on the surface of the Ni substrate, wherein Ag is crystalline and NiCoMoN is amorphous.

[0007] The aforementioned high-density heterogeneous interface catalyst is characterized in that the catalyst loading is 10 mg / cm³. 2 ~15mg / cm 2 .

[0008] This invention also discloses a method for preparing the above-mentioned high-density heterointerface catalyst, characterized in that the preparation method includes the following steps:

[0009] Step 1: Immerse the Ni substrate in a hydrothermal reaction solution and carry out a hydrothermal reaction at 120℃~180℃ to obtain the precursor Ag / NiCoMoO / Ni; the molar ratio of cobalt salt, molybdate, and silver salt in the hydrothermal reaction solution is 1:1:0.1~1, and the total metal ion concentration in the hydrothermal reaction solution is 0.07mol / L~0.10mol / L;

[0010] Step 2: The Ag / NiCoMoO / Ni obtained in Step 1 is subjected to nitriding treatment at 250℃~450℃ under NH3 atmosphere to obtain the catalyst Ag / NiCoMoN / Ni.

[0011] This invention utilizes a Ni substrate and Ag-containing materials. + The hydrothermal reaction solution undergoes an electrodisplacement reaction during the hydrothermal reaction process (i.e., Rapid nucleation occurs, causing the Ni substrate to change from silver to black, while Ni is displaced. 2+ It enters the solution; as the reaction temperature increases, the displaced Ni... 2+ Co in the hydrothermal reaction solution 2+ MoO4 2- A co-deposition reaction begins, generating NiCoMoO ternary oxide; finally, Ag / NiCoMoN / Ni is obtained through nitriding treatment.

[0012] The method for preparing a high-density heterogeneous interface catalyst described above is characterized in that the Ni substrate in step one is one of Ni foil, Ni mesh, nickel foam, and nickel felt.

[0013] The above-mentioned method for preparing a high-density heterogeneous interface catalyst is characterized in that, in step one, the cobalt salt is one or more of cobalt nitrate, cobalt chloride, and cobalt sulfate; the molybdate is one or more of ammonium molybdate, sodium molybdate, and potassium molybdate; and the silver salt is one or more of silver nitrate, silver citrate, and silver sulfate.

[0014] The method for preparing a high-density heterogeneous interface catalyst described above is characterized in that the hydrothermal reaction in step one lasts for 3 to 6 hours.

[0015] The method for preparing a high-density heterogeneous interface catalyst described above is characterized in that the heating rate of the hydrothermal reaction in step one is 5℃ / min~10℃ / min.

[0016] The method for preparing a high-density heterogeneous interface catalyst described above is characterized in that the nitriding treatment in step two lasts for 1 to 3 hours.

[0017] In addition, the present invention also discloses the application of the above-mentioned high-density heterogeneous interface catalyst, characterized in that the application of the catalyst includes the preparation of cathode materials for water electrolysis to produce hydrogen, anode materials for hydrazine oxidation reaction, and cathode and / or anode materials for hydrazine-assisted seawater electrolysis to produce hydrogen.

[0018] Compared with the prior art, the present invention has the following advantages:

[0019] 1. The high-density heterostructure catalyst of this invention possesses a unique heterostructure of crystalline Ag and amorphous NiCoMoN, which optimizes interfacial electron transport kinetics, exposes more active sites, and significantly improves charge transfer efficiency. The presence of amorphous material endows the catalyst with excellent resistance to chloride ion corrosion and exhibits superior stability in seawater environments. Furthermore, the high-density heterostructure effectively suppresses the occurrence of competitive chlorine evolution side reactions, improving its resistance to impurity interference in complex seawater environments. Simultaneously, the electronic structure of the catalytic center is effectively regulated through interface engineering, enabling the catalyst to possess both excellent HER and HzOR activities. This catalyst realizes the synergistic effect of high-density heterostructures in seawater electrolysis systems, providing a new approach for designing highly efficient and stable bifunctional catalysts.

[0020] 2. The catalyst of this invention exhibits excellent bifunctional catalytic performance, achieving ultra-low overpotential in alkaline seawater systems and significantly reducing energy consumption; at 300 mA / cm 2 This catalyst requires only 0.324V at industrial-grade current density, outperforming existing commercial Pt / C and NiCo-based catalysts. It also exhibits extremely high stability and energy efficiency at 500mA / cm². 2 It can operate continuously for more than 17 hours at high current density without attenuation and is resistant to high concentrations of Cl. -The corrosion of hydrazine is reduced, and it is applied to hydrazine-assisted seawater electrolysis systems. Compared with traditional water electrolysis, the voltage is reduced by 1.56V, and the energy saving rate is more than 30%.

[0021] 3. The catalyst of this invention can effectively solve the technical bottlenecks faced in the field of seawater electrolysis hydrogen production, and provides an innovative solution for the large-scale production of green hydrogen energy.

[0022] 4. The preparation method of the present invention cleverly couples the substitution reaction and the co-deposition reaction in one step to achieve in-situ composite of crystalline Ag and amorphous nickel cobalt molybdenum oxide, thereby obtaining a catalyst with a high interface density heterostructure. The preparation method is simple and controllable, low in cost, and easy to scale up for production.

[0023] The technical solution of the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. Attached Figure Description

[0024] Figure 1 Scanning electron microscope images of Ag / NCMN / NF prepared in Example 1 at different magnifications.

[0025] Figure 2 This is a high-resolution transmission electron microscope image of the Ag / NCMN nanosheets prepared in Example 1.

[0026] Figure 3 Transmission electron microscopy (TEM) image and selected area electron diffraction (SED) pattern of the Ag / NCMN nanosheets prepared in Example 1.

[0027] Figure 4 The elemental distribution diagram is shown for the Ag / NCMN nanosheets prepared in Example 1.

[0028] Figure 5 HER polarization curves of the catalyst prepared in Example 1 in different environments.

[0029] Figure 6 Potential-time curves of HER and HzOR for the catalyst prepared in Example 1 in alkaline seawater containing 0.5 mol / L N2H4.

[0030] Figure 7 Polarization curves of a two-electrode alkaline electrolyzer constructed with the catalyst prepared in Example 1 and a conventional alkaline electrolyzer.

[0031] Figure 8 The voltage-time curve of the HSE stability test of the catalyst prepared in Example 1 in alkaline natural seawater containing 0.5 mol / L N2H4.

[0032] Figure 9 The X-ray diffraction patterns are those of the catalysts prepared in Example 1, Comparative Example 1, and Comparative Example 2.

[0033] Figure 10 The HzOR polarization curves of the catalysts prepared in Example 1, Comparative Examples 1 and 2 in alkaline seawater containing 0.5 mol / L N2H4 are shown.

[0034] Figure 11 The HER polarization curves of the catalysts prepared in Example 1 and Comparative Examples 1-4 in 1 mol / L KOH are shown.

[0035] Figure 12 High-resolution transmission electron microscopy image of the catalyst prepared for Comparative Example 5.

[0036] Figure 13 The HER polarization curves of the catalysts prepared in Examples 1-4 in 1 mol / L KOH are shown.

[0037] Figure 14 The HzOR polarization curves of the catalysts prepared in Examples 1-4 in alkaline seawater containing 0.5 mol / L N2H4 are shown. Detailed Implementation

[0038] Example 1

[0039] The catalyst in this embodiment comprises nickel foam and Ag / NiCoMoN nanosheets grown in situ on the surface of the nickel foam, wherein Ag is crystalline and NiCoMoN is amorphous, and the catalyst loading is 13.6 mg / cm³. 2 .

[0040] The preparation method of this embodiment includes the following steps:

[0041] Step 1: The nickel foam (denoted as NF) was ultrasonically cleaned sequentially with 3 mol / L HCl, ethanol, and deionized water for 15 min each, and then dried in a 60℃ oven. It was then immersed in a hydrothermal reaction solution, sealed, and subjected to a hydrothermal reaction at 150℃ for 6 h. After natural cooling, it was washed three times alternately with deionized water and ethanol, and then vacuum dried at 60℃ to obtain the precursor Ag / NiCoMoO / NF, denoted as Ag / NCMO / NF. The molar ratio of cobalt nitrate, ammonium molybdate, and silver nitrate in the hydrothermal reaction solution was 1:1:0.5, and the total metal ion concentration in the hydrothermal reaction solution was 0.08 mol / L.

[0042] Step 2: Place the Ag / NCMO / NF obtained in Step 1 in a tube furnace and nitrid it at 350℃ for 2 hours under an NH3 atmosphere at a rate of 10℃ / min. After natural cooling, the catalyst Ag / NiCoMoN / NF is obtained, denoted as Ag / NCMN / NF.

[0043] Microscopic analysis was performed on the Ag / NCMN / NF prepared in this embodiment, such as... Figure 1 As shown, the morphology of the Ag / NCMN / NF is that Ag / NCMN nanosheets are upright grown on the NF substrate. The Ag / NCMN nanosheets were ultrasonically detached from the NF substrate and analyzed using high-resolution transmission electron microscopy (HRTEM). Figure 2 As shown, the Ag / NCMN nanosheets exhibit a densely distributed high-density crystalline-amorphous heterostructure interface (the interface is marked with a white dashed line, the region corresponding to amorphous NCMN is marked with cyan, and the remainder is crystalline Ag). Transmission electron microscopy (TEM) and selected area electron diffraction (SAED) were used to analyze the Ag / NCMN nanosheets, as shown in the figure. Figure 3 As shown, 0.26 nm and 0.21 nm correspond to the (111) and (200) planes of crystalline Ag, respectively, which are consistent with the diffraction pattern analysis results in SAED; as Figure 4 As shown, the Ag, Ni, Co, Mo, and N elements are uniformly distributed in the Ag / NCMN nanosheets.

[0044] The HER performance of the Ag / NCMN / NF catalyst prepared in this embodiment was tested in different alkaline electrolyte systems, and the results are as follows: Figure 5 As shown, the catalyst exhibits excellent HER activity in 1 mol / L KOH prepared with pure water (denoted as 1M KOH), 1 mol / L KOH prepared with natural seawater (collected from Sanya, Hainan) (denoted as alkaline seawater), and alkaline seawater electrolyte containing 0.5 mol / L N2H4 (denoted as alkaline seawater + 0.5M N2H4), with small differences in polarization curves, demonstrating good environmental adaptability; at a cathode of 10 mA / cm 2 HER overpotential (η) of Ag / NCMN / NF catalyst at current density 10 The values ​​were 38mV, 36mV, and 38mV respectively; at the cathode, 100mA / cm 2 At high current densities, the corresponding overpotentials are 115mV, 132mV, and 124mV, respectively, with a small error range. This indicates that the catalyst can maintain stable HER catalytic performance under different water sources and electrolyte environments, demonstrating its excellent resistance to impurity interference and practical applicability to seawater electrolysis. This provides reliable technical support for the efficient production of hydrogen directly from natural seawater.

[0045] The Ag / NCMN / NF catalyst prepared in this embodiment was tested using a chronopotentiometric method in an alkaline seawater system containing 0.5 mol / L N2H4 at 100 mA / cm². 2 The catalytic stability of HzOR and HER was continuously tested for 25 hours at high current density, and the results are as follows: Figure 6As shown, the operating potentials of both the HzOR and HER processes remained highly stable throughout the entire test period, with no significant potential increase observed (potential fluctuations less than 5%). This excellent stability can be attributed to the following key factors: (1) the high-density crystalline-amorphous heterostructure constructed in the catalyst exhibits significant structural stability in the strongly alkaline and complex seawater environment containing N2H4; (2) the strong interaction between Ag and NCMN effectively prevents the loss or aggregation of active components; and (3) the unique interfacial electronic structure enhances the catalyst's tolerance to impurity ions in complex media. The catalyst maintains stable performance in both the simultaneous HzOR and HER processes, a characteristic that makes it of significant practical application value in hydrazine-assisted seawater electrolysis hydrogen production systems. Compared with traditional noble metal catalysts, the stability advantage of Ag / NCMN / NF in seawater systems is particularly prominent, providing a new design idea for developing efficient and stable seawater electrolysis catalysts.

[0046] A two-electrode hydrazine composite alkaline seawater electrolyzer was constructed using Ag / NCMN / NF as both anode and cathode. Hydrogen evolution reaction (HER) occurs at the cathode, while the anode reaction utilizes the thermodynamically more favorable hydrazine oxidation (HzOR) (0.05V vs. RHE) instead of the energy-intensive oxygen evolution reaction (OER) (approximately 1.5V vs. RHE) found in traditional alkaline electrolyzers, significantly reducing the anode overpotential. The Ag / NCMN / NF electrode efficiently catalyzes both the cathode HER and the anode HzOR, avoiding the dependence on precious metals (IrO2 / Pt) found in traditional systems. The unique electrode structure design provides excellent resistance to seawater corrosion, eliminating the need for complex dechlorination pretreatment. This provides a new approach for developing efficient and low-cost seawater hydrogen production technology, solving key problems such as high energy consumption, high cost, and poor seawater adaptability of traditional electrolyzers. Figure 7 As shown, this dual-electrode HSE ("HzOR-HER" coupled mixed seawater electrolysis system, using alkaline seawater containing 0.5 mol / L N2H4 as the electrolyte, denoted as alkaline seawater + 0.5 M N2H4) electrolyzer requires only an ultra-low battery voltage of 167 mV to drive 100 mA / cm². 2 The current density of this invention is reduced by approximately 1.59V compared to the traditional alkaline electrolyzer HER+OER (which uses pure water to prepare 1 mol / L KOH as the electrolyte, denoted as 1M KOH; and natural seawater (Sanya, Hainan) to prepare 1 mol / L KOH as the electrolyte, denoted as alkaline seawater), significantly improving energy conversion efficiency. Furthermore, the voltage reduction advantage becomes even more pronounced with increasing current density, fully demonstrating the crucial role of the high-density heterogeneous interface structure of this invention in enhancing catalytic activity and reducing energy consumption.

[0047] The HER, HzOR, and HSE performance of the Ag / NCMN / NF prepared in this embodiment and existing bifunctional catalysts in alkaline systems were compared. The results are shown in Table 1 (~ in Table 1 indicates that the value is a rough estimate derived from the data graph in the reference).

[0048] Table 1 Performance results of HER, HzOR, and HSE

[0049]

[0050] As shown in Table 1, through a systematic comparison of transition metal-based bifunctional catalysts, the Ag / NCMN / NF catalyst of this invention exhibits comprehensive performance advantages: (1) Synergistic optimization of three functions: In terms of the dual-electrode catalytic performance in HER, HzOR and HSE systems, Ag / NCMN / NF outperforms most catalysts with similar structures or compositions reported in recent years; especially in the complete HSE system, V 10 =36mV is a breakthrough performance, with only a slight difference compared to precious metal catalysts such as CC@WO3 / Ru-450, and far superior to non-precious metal systems such as NiCo-MoNi4. (2) Advantages in industrial application: at 100mA / cm 2 At industrial-grade current densities, Ag / NCMN / NF significantly outperforms existing materials at a cell voltage of 114mV in HSE. The direct growth characteristics of Ag / NCMN / NF on NF substrates (compared to Cu-CoFe / Co / NC, which require complex support treatment) better meet the needs of large-scale production. Furthermore, Ag / NCMN / NF achieves near-precious metal catalyst performance while maintaining the cost advantage of non-precious metals, providing an innovative solution for the practical application of HSE electrolyzers.

[0051] The Ag / NCMN / NF prepared in this embodiment was subjected to an A / cm² temperature of 500 mA / cm². 2 A 17-hour continuous electrolysis test was conducted under high current conditions, with fresh electrolyte replenished every 5 hours. The results are as follows: Figure 8 As shown, the Ag / NCMN / NF||Ag / NCMN / NF electrolyzer maintained a stable operating voltage of 1.5V~1.7V throughout the entire test process and never reached the initiation potential of the chlorine evolution reaction (ClER). These results confirm the structural stability of Ag / NCMN / NF under extreme conditions, solve the problem of chlorine corrosion in seawater electrolysis, and provide a reliable technical solution for large-scale industrial seawater hydrogen production.

[0052] In summary, this invention successfully constructed a bifunctional Ag / NCMN / NF catalyst with a high-density crystalline-amorphous heterostructure via an innovative one-step preparation process. Material characterization results confirm that this catalyst possesses a unique heterostructure structure and uniform elemental distribution, providing abundant active sites for efficient catalysis, and exhibits excellent catalytic activity and stability in both HER and HzOR reactions.

[0053] Comparative Example 1

[0054] The difference between Comparative Example 1 and Example 1 is that the hydrothermal reaction solution in step one contains only Co. 2+ and MoO4 2- The molar ratio of cobalt chloride to ammonium molybdate in the hydrothermal reaction solution was 1:1, and the total metal ion concentration in the hydrothermal reaction solution was 0.07 mol / L; the catalyst NiCoMoN / NF was obtained, denoted as NCMN / NF.

[0055] Comparative Example 2

[0056] The difference between Comparative Example 1 and Example 1 is that the hydrothermal reaction solution in step one contains only Ag. + Silver nitrate was used in the hydrothermal reaction solution, and the total metal ion concentration in the hydrothermal reaction solution was 0.02 mol / L; the nitriding treatment in step two was not performed; the catalyst Ag / NF was obtained.

[0057] XRD patterns of the Ag / NCMN / NF prepared in Example 1, the NCMN / NF prepared in Comparative Example 1, and the Ag / NF prepared in Comparative Example 2 were analyzed. Figure 9 As shown, all three exhibit diffraction peaks at 44.6°, 52.0°, and 76.5°, which are attributed to the substrate NF (JCPDS No. 65-2865). Ag / NCMN / NF and Ag / NF both show peaks at 38.1°, 64.4°, and 77.4°, which are attributed to the (111), (220), and (311) crystal planes of Ag (JCPDS No. 65-2871), respectively. NCMN exists in an amorphous form, indicating the presence of a crystalline-amorphous heterostructure interface within the Ag / NCMN / NF catalyst.

[0058] The HzOR performance of Ag / NCMN / NF prepared in Example 1, NCMN / NF prepared in Comparative Example 1, and Ag / NF prepared in Comparative Example 2 were tested in alkaline seawater containing 0.5 mol / L N2H4. The results are as follows: Figure 10 As shown, Ag / NCMN / NF with a high-density crystalline-amorphous heterostructure exhibits a significant HzOR activity advantage: at 10 mA / cm², 2At the specified current density, the overpotential of Ag / NCMN / NF was only -50 mV, while the required potentials for NCMN / NF and Ag / NF were -46 mV and 52 mV, respectively. The results show that Ag / NF exhibits almost no catalytic activity for HzOR, while the presence of NCMN / NF significantly enhances HzOR performance. This indicates that the amorphous NCMN phase plays a crucial role in HzOR catalysis. This performance difference fully demonstrates that the high-density crystalline-amorphous interface constructed in this invention via a one-step method can significantly improve HzOR catalytic activity, providing a new approach for developing highly efficient bifunctional seawater electrolysis catalysts.

[0059] Comparative Example 3

[0060] The catalyst in this embodiment is the nickel foam (NF) that has been ultrasonically cleaned and dried in Example 1.

[0061] Comparative Example 4

[0062] The preparation method of this comparative example includes the following steps:

[0063] Step 1: The nickel foam was ultrasonically cleaned for 15 minutes each with 3 mol / L HCl, ethanol and deionized water, and then dried in a 60℃ oven.

[0064] Step 2: Weigh 4 mg of commercial Pt / C catalyst (20 wt% Pt) and place it in a 1 mL glass sample bottle. Add 500 μL of ethanol, 480 μL of ultrapure water and 20 μL of 5% Nafion solution (perfluorosulfonic acid polymer solution) and disperse evenly to obtain a mixture.

[0065] Step 3: Take 250 μL of the mixture obtained in Step 2 and slowly drip it onto the cut NF surface (1 cm × 1 cm). Allow it to air dry naturally to obtain a loading of 1 mg / cm². 2 Pt / C electrode.

[0066] HER polarization curves of the catalysts of Example 1 and Comparative Examples 1-4 were measured in 1 mol / L KOH at a scan rate of 5 mV / s with 90% iR compensation. A three-electrode system was used, with the catalysts of Example 1 and Comparative Examples 1-4 as the working electrode, a graphite rod as the counter electrode, and mercury oxide as the reference electrode. The measured polarization curves are shown below. Figure 11 As shown, the Ag / NCMN / NF prepared in Example 1 was subjected to a current density of 10 mA / cm². 2 The overpotential at this time is only 38 mV, second only to the catalytic performance of the commercial Pt / C prepared in Comparative Example 4 (η). 10 =22mV), which is much lower than the NCMN / NF (η0) prepared in Comparative Example 1. 10 =59mV) and the Ag / NF (η) prepared in Comparative Example 2. 10=183mV). A similar trend is observed when higher current densities are reached: the overpotential required for Ag / NCMN / NF remains relatively low, while Ag / NF and the substrate NF exhibit poor HER catalytic activity; indicating that the main HER catalytic activity of Ag / NCMN / NF comes from the NCMN phase, and the heterostructure Ag / NCMN / NF, which is composited with high-density crystalline Ag, exhibits the best HER catalytic activity.

[0067] Comparative Example 5

[0068] The preparation method of this comparative example includes the following steps:

[0069] Step 1: Nickel foam (NF) was ultrasonically cleaned sequentially with 3 mol / L HCl, ethanol, and deionized water for 15 min each, and then dried in a 60℃ oven. It was then immersed in the first hydrothermal reaction solution, sealed, and subjected to a hydrothermal reaction at 150℃ for 6 h. After natural cooling, it was washed three times alternately with deionized water and ethanol, and then vacuum dried at 60℃ to obtain the Ag / NF precursor. The first hydrothermal reaction solution contained only Ag. + The first hydrothermal reaction solution contains silver nitrate, and the total metal ion concentration in the first hydrothermal reaction solution is 0.02 mol / L.

[0070] Step 2: Immerse the Ag / NF precursor obtained in Step 1 into the second hydrothermal reaction solution, seal it, and perform a hydrothermal reaction at 150℃ for 6 hours. After natural cooling, wash it three times alternately with deionized water and ethanol, and then vacuum dry it at 60℃ to obtain Ag@NiCoMoO / NF; the second hydrothermal reaction solution contains only Co. 2+ and MoO4 2- The molar ratio of cobalt nitrate to ammonium molybdate in the second hydrothermal reaction solution is 1:1, and the total metal ion concentration in the second hydrothermal reaction solution is 0.07 mol / L.

[0071] Step 3: Place the Ag@NiCoMoO / NF precursor obtained in Step 2 in a tube furnace and nitrid it at 350℃ for 2 hours under an NH3 atmosphere at a rate of 10℃ / min. After natural cooling, the catalyst Ag@NiCoMoN / NF is obtained, denoted as Ag@NCMN / NF.

[0072] Microscopic analysis was performed on the Ag@NCMN / NF prepared in this comparative example, such as... Figure 12As shown, the catalyst did not form a distinct crystalline-amorphous heterostructure over a large area, indicating that the heterostructures prepared by traditional multi-step methods have inherent defects such as heterogeneous layered distribution and sparse interfaces. In contrast, the Ag / NCMN / NF in Example 1 exhibits a heterogeneous and uniform distribution with a high-density heterostructure interface that runs throughout the entire material. This demonstrates that the one-step in-situ construction strategy adopted in this invention can effectively overcome the interface control limitations of traditional multi-step methods, achieving atomic-level uniform composite of heterogeneous components, thereby significantly improving the density of interfacial active sites and laying a structural foundation for efficient seawater electrolysis to produce hydrogen.

[0073] Example 2

[0074] The catalyst in this embodiment comprises nickel foam and Ag / NiCoMoN nanosheet structures grown in situ on the surface of the nickel foam, wherein Ag is crystalline and NiCoMoN is amorphous, and the catalyst loading is 13.1 mg / cm³. 2 .

[0075] The preparation method of this embodiment includes the following steps:

[0076] Step 1: The nickel foam (denoted as NF) was ultrasonically cleaned sequentially with 3 mol / L HCl, ethanol, and deionized water for 15 min each, and then dried in a 60℃ oven. It was then immersed in a hydrothermal reaction solution, sealed, and subjected to a hydrothermal reaction at 150℃ for 6 h. After natural cooling, it was washed three times alternately with deionized water and ethanol, and then vacuum dried at 60℃ to obtain the precursor Ag / NiCoMoO / NF, denoted as Ag / NCMO / NF. The molar ratio of cobalt nitrate, ammonium molybdate, and silver nitrate in the hydrothermal reaction solution was 1:1:0.1, and the total metal ion concentration in the hydrothermal reaction solution was 0.07 mol / L.

[0077] Step 2: Place the Ag / NCMO / NF precursor obtained in Step 1 in a tube furnace and nitrid it at 350℃ for 2 hours under NH3 atmosphere at a rate of 10℃ / min. After natural cooling, the catalyst Ag / NiCoMoN / NF is obtained, denoted as Ag / NCMN / NF.

[0078] Example 3

[0079] The catalyst in this embodiment comprises nickel foam and Ag / NiCoMoN nanosheets grown in situ on the surface of the nickel foam, wherein Ag is crystalline and NiCoMoN is amorphous, and the catalyst loading is 14.2 mg / cm³. 2 .

[0080] The preparation method of this embodiment includes the following steps:

[0081] Step 1: The nickel foam (denoted as NF) was ultrasonically cleaned sequentially with 3 mol / L HCl, ethanol, and deionized water for 15 min each, and then dried in a 60℃ oven. It was then immersed in a hydrothermal reaction solution, sealed, and subjected to a hydrothermal reaction at 150℃ for 6 h. After natural cooling, it was washed three times alternately with deionized water and ethanol, and then vacuum dried at 60℃ to obtain the precursor Ag / NiCoMoO / NF, denoted as Ag / NCMO / NF. The molar ratio of cobalt nitrate, ammonium molybdate, and silver nitrate in the hydrothermal reaction solution was 1:1:1, and the total metal ion concentration in the hydrothermal reaction solution was 0.10 mol / L.

[0082] Step 2: Place the Ag / NCMO / NF precursor obtained in Step 1 in a tube furnace and nitrid it at 350℃ for 2 hours under NH3 atmosphere at a rate of 10℃ / min. After natural cooling, the catalyst Ag / NiCoMoN / NF is obtained, denoted as Ag / NCMN / NF.

[0083] Example 4

[0084] The catalyst in this embodiment comprises a Ni mesh substrate and Ag / NCMN nanosheet structures grown in situ on the Ni mesh surface, wherein Ag is crystalline and NCMN is amorphous, and the catalyst loading is 13.2 mg / cm³. 2 .

[0085] The preparation method of this embodiment includes the following steps:

[0086] Step 1: The Ni mesh (denoted as NM) was ultrasonically cleaned sequentially with 3 mol / L HCl, ethanol, and deionized water for 15 min each, and then dried in a 60℃ oven. It was then immersed in a hydrothermal reaction solution, sealed, and subjected to a hydrothermal reaction at 150℃ for 6 h. After natural cooling, it was washed three times alternately with deionized water and ethanol, and then vacuum dried at 60℃ to obtain the precursor Ag / / NiCoMoO / NM, denoted as Ag / NCMO / NM. The molar ratio of cobalt nitrate, ammonium molybdate, and silver nitrate in the hydrothermal reaction solution was 1:1:0.5, and the total metal ion concentration in the hydrothermal reaction solution was 0.08 mol / L.

[0087] Step 2: Place the Ag / NCMO / NM precursor obtained in Step 1 in a tube furnace and nitrid it at 350℃ for 2 hours under an NH3 atmosphere at a rate of 10℃ / min. After natural cooling, the catalyst Ag / NiCoMoN / NM is obtained, denoted as Ag / NCMN / NM.

[0088] The catalysts prepared in Examples 1-4 were tested for HER catalytic performance in 1 mol / L KOH solution (denoted as 1M KOH), and the results are as follows: Figure 13As shown; the HzOR catalytic performance of the catalysts prepared in Examples 1-4 was tested in a 1 mol / L KOH electrolyte containing 0.5 mol / L N2H4, and the results are as follows. Figure 14 As shown. Compared to the Ag / NCMN / NF of Example 1, the Ag / NCMN / NF of Example 2, due to its lower content of crystalline Ag, exhibited decreased conductivity and a reduced heterostructure interface, resulting in reduced HER and HzOR performance. While the Ag / NCMN / NF of Example 3 had a higher content of crystalline Ag, the excessively high proportion of crystalline Ag actually reduced the content of the active phase, amorphous NCMN, thereby inhibiting catalytic activity. This indicates that an appropriate ratio of crystalline Ag to amorphous NCMN is crucial for optimizing HER and HzOR performance. Furthermore, when the substrate NF was replaced with NM, the HER and HzOR catalytic performance of the Ag / NCMN / NM of Example 4 showed a significant decrease. This was mainly attributed to the poor conductivity and low specific surface area of ​​the NM substrate, which hindered the full exposure of active sites and rapid electron transport, thus affecting the overall catalytic efficiency.

[0089] Example 5

[0090] The catalyst in this embodiment comprises nickel foam and Ag / NiCoMoN nanosheet structures grown in situ on the surface of the nickel foam, wherein Ag is crystalline and NiCoMoN is amorphous, and the catalyst loading is 13.4 mg / cm³. 2 .

[0091] The difference between this embodiment and Embodiment 1 is that the temperature of the hydrothermal reaction in step one is 120°C, the heating rate of the hydrothermal reaction is 5°C / min, and the duration of the hydrothermal reaction is 3 hours.

[0092] Example 6

[0093] The catalyst in this embodiment comprises nickel foam and Ag / NiCoMoN nanosheets grown in situ on the surface of the nickel foam, wherein Ag is crystalline and NiCoMoN is amorphous, and the catalyst loading is 14.2 mg / cm³. 2 .

[0094] The difference between this embodiment and Embodiment 1 is that the temperature of the hydrothermal reaction in step one is 180℃, the heating rate of the hydrothermal reaction is 9℃ / min, and the duration of the hydrothermal reaction is 5.5h.

[0095] Example 7

[0096] The catalyst in this embodiment comprises nickel foam and Ag / NiCoMoN nanosheet structures grown in situ on the surface of the nickel foam, wherein Ag is crystalline and NiCoMoN is amorphous, and the catalyst loading is 13.7 mg / cm³. 2 .

[0097] The difference between this embodiment and Embodiment 1 is that the nitriding temperature in step two is 250°C and the nitriding treatment time is 3 hours.

[0098] Example 8

[0099] The catalyst in this embodiment comprises nickel foam and Ag / NiCoMoN nanosheet structures grown in situ on the surface of the nickel foam, wherein Ag is crystalline and NiCoMoN is amorphous, and the catalyst loading is 10.6 mg / cm³. 2 .

[0100] The difference between this embodiment and Embodiment 1 is that the nitriding temperature in step two is 450°C and the nitriding treatment time is 1 hour.

[0101] In this embodiment, the foamed nickel can be replaced with Ni foil or nickel felt, the cobalt nitrate can be replaced with one or two of cobalt chloride and cobalt sulfate, the ammonium molybdate can be replaced with one or two of sodium molybdate and potassium molybdate, and the silver nitrate can be replaced with one or two of silver citrate and silver sulfate.

[0102] Systematic electrochemical performance tests showed that the catalysts prepared in Examples 5-8 exhibited excellent catalytic activity for hydrogen evolution reaction (HER), hydrazine oxidation reaction (HzOR), and overall hydrazine electrolysis (HSE) in hydrazine-containing alkaline seawater systems, while also possessing good long-term stability. This characteristic makes the catalysts have significant application potential in the field of seawater electrolysis for hydrogen production.

[0103] The above description is merely a preferred embodiment of the present invention and does not constitute any limitation on the present invention. Any simple modifications, alterations, or equivalent structural transformations made to the above embodiments based on the technical essence of the present invention shall still fall within the protection scope of the present invention.

Claims

1. A high-density heterointerface catalyst, characterized by, The catalyst comprises a Ni substrate and an Ag / NiCoMoN nanosheet structure grown in situ on the surface of the Ni substrate, wherein Ag is crystalline and NiCoMoN is amorphous.

2. The high-density heterointerface catalyst according to claim 1, wherein The catalyst is loaded at 10 mg / cm 2 15 mg / cm 2 .

3. A method for preparing a high-density heterogeneous interface catalyst as described in claim 1 or 2, characterized in that, The preparation method includes the following steps: Step 1: Immerse the Ni substrate in a hydrothermal reaction solution and carry out a hydrothermal reaction at 120℃~180℃ to obtain the precursor Ag / NiCoMoO / Ni; the molar ratio of cobalt salt, molybdate, and silver salt in the hydrothermal reaction solution is 1:1:0.1~1, and the total metal ion concentration in the hydrothermal reaction solution is 0.07mol / L~0.10mol / L; Step 2: The Ag / NiCoMoO / Ni obtained in Step 1 is subjected to nitriding treatment at 250℃~450℃ under NH3 atmosphere to obtain the catalyst Ag / NiCoMoN / Ni.

4. The method for preparing a high-density heterogeneous interface catalyst according to claim 3, characterized in that, The Ni substrate mentioned in step one is one of Ni foil, Ni mesh, nickel foam, or nickel felt.

5. The method for preparing a high-density heterogeneous interface catalyst according to claim 3, characterized in that, The cobalt salt mentioned in step one is one or more of cobalt nitrate, cobalt chloride, and cobalt sulfate; the molybdate is one or more of ammonium molybdate, sodium molybdate, and potassium molybdate; and the silver salt is one or more of silver nitrate, silver citrate, and silver sulfate.

6. The method for preparing a high-density heterogeneous interface catalyst according to claim 3, characterized in that, The duration of the hydrothermal reaction in step one is 3 to 6 hours.

7. The method for preparing a high-density heterogeneous interface catalyst according to claim 3, characterized in that, The heating rate of the hydrothermal reaction in step one is 5℃ / min to 10℃ / min.

8. The method for preparing a high-density heterogeneous interface catalyst according to claim 3, characterized in that, The nitriding treatment in step two lasts for 1 to 3 hours.

9. The application of a high-density heterogeneous interface catalyst as described in claim 1 or 2, characterized in that, The catalyst is used in the preparation of cathode materials for water electrolysis to produce hydrogen, anode materials for hydrazine oxidation reactions, and cathode and / or anode materials for hydrazine-assisted seawater electrolysis to produce hydrogen.

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