Ni-based noble metal monatomic catalyst, preparation method and application thereof

Abstract

The present application relates to the technical field of hydrogen production material by electrolysis of water, in particular to a Ni-based noble metal monatomic catalyst, a preparation method and application thereof; the Ni-based noble metal monatomic catalyst takes carbon paper as a substrate, and is obtained by one-step single-pulse in-situ electrodeposition on the pretreated carbon paper. The single-stage pulse deposition method controls the deposition potential, pulse interval, duty cycle and addition of complex, and weakens the influence of concentration polarization on metal ion reduction, thereby obtaining different noble metal monatomic. The present application can obtain different noble metal monatomic with ultra-low loading, realize rapid and large-scale preparation, and provide a preparation strategy of high-activity and low-cost hydrogen evolution catalyst, which has excellent hydrogen evolution activity and good durability under alkaline conditions, and has great application prospect.

Description

Technical Field

[0001] This invention relates to the field of materials technology for hydrogen production through water electrolysis, specifically to a Ni-based noble metal single-atom catalyst and its preparation method and application. Background Technology

[0002] Hydrogen energy, as a new type of clean energy with high energy density, has become an important vehicle for energy conservation and emission reduction. Under the low-carbon context, a comprehensive comparison of various hydrogen production routes reveals that the hydrogen evolution reaction (HER) via electrochemical water splitting is considered a clean and sustainable hydrogen production path. However, compared to HER reactions in acidic media, the kinetics of the HER reaction are limited by the additional challenges of water splitting and strong alkaline corrosion in strongly alkaline environments. Therefore, developing a highly active, alkaline-stable HER electrocatalyst is challenging but of great significance for the future realization of industrial hydrogen production.

[0003] Platinum (Pt)-based noble metal catalysts (Ir / Ru / Au) are considered to possess optimal HER reaction kinetics due to their suitable electronic structure and adsorption environment, but their high cost and scarcity limit their large-scale application. To maximize the utilization of noble metals, reducing the noble metal loading or shrinking the size of the noble metal is undoubtedly the future direction for noble metal catalysts. In fact, scale tuning is an effective way to regulate functional materials, as smaller catalysts can provide more active sites, such as single atoms of noble metals with unique electronic properties. Therefore, shrinking the scale of noble metal materials to the single-atom scale can both reduce the noble metal loading and maximize its activity. However, it is precisely because of the characteristics of these single sites that their persistence under alkaline conditions and the need to regulate multi-directional active sites limit large-scale application. Therefore, the rational application of noble metal single-atom catalysts to achieve HER under alkaline conditions is challenging but crucial.

[0004] Currently, methods for controlling the chemical environment and electronic structure around single atoms include defect engineering, annealing, interaction with the support, and the introduction of nanoclusters. While these strategies have made some progress, the demanding synthesis conditions and complex design steps can complicate the correlation between the electronic environment around single atoms and catalytic performance. Alloying is a simple and reasonable approach to controlling the chemical environment and electronic structure around metals, and lattice effects can also be achieved through stress regulation. However, there are few reports on improving intermediate adsorption by adjusting the chemical structure around noble metal single atoms through alloying. Traditional alloy catalysts are mostly obtained through thermal reduction or potentiostatic reduction, resulting in simple structures and the inability to obtain homogeneous single-atom-metal alloys in one step. Furthermore, nickel (Ni), as a transition metal in the same group as Pt, holds promise as an effective HER catalyst due to its similar electronic structure, potentially replacing Pt-type noble metals. Therefore, designing Ni-modified noble metal single-atom catalysts through reasonable methods to obtain optimized adsorption environments and electronic structures, while simultaneously promoting the stability of noble metal single atoms under alkaline conditions, could contribute to achieving low-cost, high-efficiency hydrogen production through water electrolysis. Summary of the Invention

[0005] This invention overcomes the shortcomings of the prior art and provides a Ni-based noble metal single-atom catalyst.

[0006] To solve the above-mentioned technical problems, the technical solution adopted by the present invention is as follows: a Ni-based noble metal single-atom catalyst, which is a noble metal single-atom catalyst modified with ultra-small Ni nanocrystals prepared in situ by a single-stage pulse electrodeposition method using pre-activated carbon fiber paper as a substrate, wherein the noble metal is one of Ir, Pt, Ru and Au.

[0007] The present invention also provides a method for preparing the above-mentioned Ni-based noble metal single-atom catalyst, comprising the following steps: (1) Soak the clean hydrophilic carbon paper in nitric acid solution for 30 min, clean it, and then transfer it to sulfuric acid solution for electrochemical activation (5 cycles of voltammetry) to obtain the pretreated substrate carbon paper; (2) Add nickel metal salt, soluble noble metal ion salt, boric acid, polyvinylpyrrolidone, ammonium chloride and ammonium fluoride to the aqueous solvent, stir thoroughly at room temperature until dissolved, and adjust the pH of the solution to 2.7 with dilute hydrochloric acid; (3) Using the pretreated substrate carbon paper obtained in step (1) as the working electrode, the solution obtained in step (2) is electrodeposited in situ for 8000 s in a water bath at 30°C using a unipolar pulse method. The obtained catalyst is washed several times with deionized water and ethanol, and then dried under vacuum to obtain a Ni-based noble metal single-atom catalyst.

[0008] This invention weakens the influence of concentration polarization on metal ion reduction by controlling deposition potential, pulse interval, duty cycle, and the addition of complexes through a single-stage pulse deposition method, thereby obtaining different noble metal single atoms. This invention can obtain different noble metal single atoms with ultra-low loadings, enabling rapid large-scale preparation, and provides a highly active, low-cost strategy for preparing hydrogen evolution catalysts. These catalysts exhibit excellent hydrogen evolution activity and good durability under alkaline conditions, showing great application potential.

[0009] Furthermore, in step (1), the concentration of the HNO3 solution is 1.0 M and the concentration of the H2SO4 solution is 0.5 M.

[0010] Furthermore, in step (2), the molar ratio of nickel metal salt to noble metal ion salt is 150~50000.

[0011] Furthermore, the concentration of soluble noble metal ion salts is 0.003~1 mmol / L.

[0012] Furthermore, in step (2), the concentration of nickel metal salt in the solution is 150 mmol / L, the molar ratio of boric acid to nickel metal salt is 2:15, the concentration of ammonium chloride is 20 mmol / L, the molar ratio of ammonium fluoride to ammonium chloride solution is 1:15, and the concentration of polyvinylpyrrolidone is 0.01 g / ml.

[0013] Furthermore, the potential of the unipolar pulse deposition is -2.2 V to -1.8 V vs. Hg / Hg2SO4, with the Hg / Hg2SO4 electrode serving as the reference electrode; the pulse interval of the unipolar pulse deposition is 1 s, and the duty cycle of the single-stage pulse is 0.5.

[0014] In addition, the present invention also provides the application of the above-mentioned Ni-based noble metal single-atom catalyst in alkaline water electrolysis for hydrogen production.

[0015] Compared with the prior art, the present invention has the following beneficial effects: 1. The Ni-based noble metal single-atom catalyst prepared by this invention has an ultra-low Ni nanoparticle size (1~2 nm), which exposes more active sites while modifying and stabilizing noble metal single atoms, and the atomization of noble metals greatly reduces costs.

[0016] 2. The Ni-based noble metal single-atom catalyst prepared by this invention exhibits excellent alkaline hydrogen evolution activity and stability.

[0017] 3. The process of this invention is simple and easy to operate, and different precious metal single atoms can be introduced to achieve rapid large-scale production, which has great application prospects. Attached Figure Description

[0018] Figure 1NiIr prepared in Example 1 of this invention SAs Scanning electron microscope image of the catalyst (Ni nanoparticle-modified Ir single-atom catalyst).

[0019] Figure 2 NiIr prepared in Example 1 of this invention SAs Transmission electron microscope image of the catalyst.

[0020] Figure 3 NiIr prepared in Example 1 of this invention SAs Aberration-corrected electron micrograph of the catalyst.

[0021] Figure 4 NiIr prepared in Example 1 of this invention SAs Elemental scanning energy spectrum of the catalyst.

[0022] Figure 5 NiIr prepared in Example 1 of this invention SAs X-ray diffraction pattern of the catalyst.

[0023] Figure 6 NiIr prepared in Example 1 of this invention SAs X-ray absorption near-edge structure diagram of the catalyst.

[0024] Figure 7 NiIr prepared in Example 1 of this invention SAs Polarization curves of the hydrogen evolution reaction of the catalyst (1 mol / L KOH solution).

[0025] Figure 8 NiIr prepared in Example 1 of this invention SAs Hydrogen evolution stability test curve of the catalyst.

[0026] Figure 9 NiPt prepared in Example 2 of this invention SAs Polarization curves of the electrocatalyst in 1.0 mol / L KOH for hydrogen evolution performance testing.

[0027] Figure 10 NiRu prepared in Example 3 of this invention SAs Polarization curves of the electrocatalyst in 1.0 mol / L KOH for hydrogen evolution performance testing.

[0028] Figure 11 NiAu prepared in Example 4 of this invention SAs Polarization curves of the electrocatalyst in 1.0 mol / L KOH for hydrogen evolution performance testing. Detailed Implementation

[0029] The present invention will be further described below with reference to specific embodiments. Example 1

[0030] A Ni-based noble metal single-atom catalyst for hydrogen evolution through water electrolysis includes the following steps: (1) Soak the clean carbon paper in 1.0 M HNO3 solution for 30 min, then rinse it with water and ethanol. After drying, the carbon paper is subjected to 5 cycles of voltammetry in 0.5 M H2SO4 solution, then rinsed with water and ethanol, and vacuum dried to obtain pre-activated carbon paper.

[0031] (2) Prepare 100 mL of a solution containing 1 mmol / L iridium chloride (IrCl3·xH2O), 150 mmol / L nickel chloride (NiCl2·6H2O), 20 mmol / L boric acid, 20 mmol / L ammonium chloride, 1.3 mmol / L ammonium fluoride, and 1.0 g polyvinylpyrrolidone. Adjust the pH of the solution to 2.7 with dilute hydrochloric acid. Using the pre-activated carbon paper from step (1) as the working electrode, the Hg / Hg2SO4 electrode as the reference electrode, and the platinum column as the working electrode, perform in-situ electrodeposition for 8000 s using a monopolar pulse technique on an electrochemical workstation. The deposition potential is -2.0 V vs. Hg / Hg2SO4. The obtained catalyst is washed several times with deionized water and ethanol, and then vacuum dried to obtain NiIr. SAs catalyst.

[0032] Figure 1 It is NiIr SAs Scanning electron microscope images of electrocatalysts, from Figure 1 It can be seen that the material prepared by in-situ pulses exhibits an irregular conical structure composed of small, rough-surfaced particle clusters.

[0033] Figure 2 It is NiIr SAs Transmission electron microscopy images of the catalyst, from Figure 2 It can be seen that the particle size of Ni nanocrystals is 1~2 nm. The ultra-small nanocrystal size can provide more active sites, which is more conducive to catalyzing the HER reaction.

[0034] Figure 3 It is NiIr SAs Aberration-corrected electron micrographs of the catalyst, from Figure 3 Analysis revealed that Ni exists in the form of nanocrystals, with bright spots of atomic form uniformly dispersed around it.

[0035] Figure 4 It is NiIr SAs Elemental scanning energy spectrum of the catalyst, from Figure 4The uniform distribution of Ni and Ir elements can be observed, and the elemental scanning results show that the elemental contents of Ni and Ir are 99.11 at% and 0.89 at%, respectively, indicating that the precious metal Ir has an ultra-low loading, thereby reducing costs.

[0036] Figure 5 It is NiIr SAs X-ray diffraction pattern of the catalyst, by Figure 5 It can be seen that its diffraction peaks correspond to the characteristic peaks of the substrate carbon paper and Ni nanocrystals, indicating the successful loading of Ni nanocrystals.

[0037] Figure 6 It is NiIr SAs X-ray absorption near-edge structure diagram of the catalyst, from Figure 6 It can be seen that there is a Ni-Ir coordination at 2-3 Å (compared with the standard sample), rather than an Ir-Ir bond, thus confirming that Ir exists in the form of a single atom.

[0038] Figure 7 It is NiIr SAs The hydrogen evolution reaction polarization curve of the catalyst (1 mol / L KOH solution) is derived from... Figure 8 It is evident that this electrode can undergo hydrogen evolution reaction at a relatively low overpotential, at -10 mA cm⁻¹. -2 The hydrogen evolution overpotential at the current density is only 57 mV, which fully demonstrates that the material has excellent hydrogen evolution activity.

[0039] Figure 8 It is NiIr SAs Hydrogen evolution stability test curves of the catalyst. As shown in the figure, this material exhibits stability at a current density of -10 mA cm⁻¹. -2 When the hydrogen evolution is stable for 50 hours without significant decay, it proves that the material exhibits excellent hydrogen evolution stability under long-term strongly alkaline conditions. Example 2

[0040] A Ni-based noble metal single-atom catalyst for hydrogen evolution through water electrolysis includes the following steps: (1) Soak the clean carbon paper in 1.0 M HNO3 solution for 30 min, then rinse it with water and ethanol. After drying, the carbon paper is subjected to 5 cycles of voltammetry in 0.5 M H2SO4 solution, then rinsed with water and ethanol, and vacuum dried to obtain pre-activated carbon paper.

[0041] (2) Prepare 100 mL of a solution containing 0.003 mmol / L chloroplatinic acid (H2PtCl6·xH2O), 150 mmol / L nickel chloride (NiCl2·6H2O), 20 mmol / L boric acid, 20 mmol / L ammonium chloride, 1.3 mmol / L ammonium fluoride, and 1.0 g polyvinylpyrrolidone. Adjust the pH of the solution to 2.7 with dilute hydrochloric acid. Using the pre-activated carbon paper from step (1) as the working electrode, the Hg / Hg2SO4 electrode as the reference electrode, and the platinum column as the working electrode, perform in-situ electrodeposition for 8000 s using a monopolar pulse technique on an electrochemical workstation. The deposition potential is -2.2 V vs. Hg / Hg2SO4. The obtained catalyst is washed several times with deionized water and ethanol, and then vacuum dried to obtain NiPt. SAs catalyst.

[0042] NiPt prepared in Example 2 SAs The polarization curves for the hydrogen evolution performance test of the electrocatalyst in 1.0 mol / L KOH are shown below. Figure 9 As shown, by Figure 9 It can be seen that the prepared NiPt SAs Electrocatalyst at -10 mA cm -2 The hydrogen evolution overpotential at the current density is 45 mV. Example 3

[0043] A Ni-based noble metal single-atom catalyst for hydrogen evolution through water electrolysis includes the following steps: (1) Soak the clean carbon paper in 1.0 M HNO3 solution for 30 min, then rinse it with water and ethanol. After drying, the carbon paper is subjected to 5 cycles of voltammetry in 0.5 M H2SO4 solution, then rinsed with water and ethanol, and vacuum dried to obtain pre-activated carbon paper.

[0044] (2) Prepare 100 mL of a solution containing 0.1 mmol / L ruthenium chloride (RuCl3·xH2O), 150 mmol / L nickel chloride (NiCl2·6H2O), 20 mmol / L boric acid, 20 mmol / L ammonium chloride, 1.3 mmol / L ammonium fluoride, and 1.0 g polyvinylpyrrolidone. Adjust the pH of the solution to 2.7 with dilute hydrochloric acid. Using the pre-activated carbon paper from step (1) as the working electrode, the Hg / Hg2SO4 electrode as the reference electrode, and the platinum column as the working electrode, perform in-situ electrodeposition for 8000 s using a monopolar pulse technique on an electrochemical workstation. The deposition potential is -2.2 V vs. Hg / Hg2SO4. The obtained catalyst is washed several times with deionized water and ethanol, and then vacuum dried to obtain NiRu. SAs catalyst.

[0045] NiRu prepared in Example 3SAs The polarization curves for the hydrogen evolution performance test of the electrocatalyst in 1.0 mol / L KOH are shown below. Figure 10 As shown, by Figure 10 It can be seen that the prepared NiRu SAs Electrocatalyst at -10 mA cm -2 The hydrogen evolution overpotential at the current density is only 45 mV. Example 4

[0046] A Ni-based noble metal single-atom catalyst for hydrogen evolution through water electrolysis includes the following steps: (1) Soak the clean carbon paper in 1.0 M HNO3 solution for 30 min, then rinse it with water and ethanol. After drying, the carbon paper is subjected to 5 cycles of voltammetry in 0.5 M H2SO4 solution, then rinsed with water and ethanol, and vacuum dried to obtain pre-activated carbon paper.

[0047] (2) Prepare a solution containing 0.1 mmol / L chloroauric acid ( HAuCl 4 ·4H 2 O A solution of 150 mmol / L nickel chloride (NiCl2·6H2O), 20 mmol / L boric acid, 20 mmol / L ammonium chloride, 1.3 mmol / L ammonium fluoride, and 1.0 g polyvinylpyrrolidone was prepared in 100 mL. The pH of the solution was adjusted to 2.7 with dilute hydrochloric acid. Using the pre-activated carbon paper from step (1) as the working electrode, the Hg / Hg2SO4 electrode as the reference electrode, and the platinum column as the working electrode, in-situ electrodeposition was performed for 8000 s using a monopolar pulse technique on an electrochemical workstation. The deposition potential was -1.8 V vs. Hg / Hg2SO4. The obtained catalyst was washed several times with deionized water and ethanol, and then vacuum dried to obtain NiAu. SAs catalyst.

[0048] NiAu prepared in Example 4 SAs The polarization curves for the hydrogen evolution performance test of the electrocatalyst in 1.0 mol / L KOH are shown below. Figure 11 As shown, by Figure 11 It can be seen that the prepared NiAu SAs Electrocatalyst at -10 mA cm -2 The hydrogen evolution overpotential at the current density is only 78 mV.

[0049] Finally, it should be noted that the above embodiments detail the preferred specific measures of the present invention. It should be understood that those skilled in the art can make many modifications and variations based on the concept of the present invention without creative effort. Therefore, any modifications made by those skilled in the art based on the present invention on the existing technology or based on limited experiments should be within the scope of protection defined by the claims.

Claims

1. A Ni-based noble metal single-atom catalyst, characterized in that, A noble metal single-atom catalyst modified with ultra-small Ni nanocrystals was prepared in situ by unipolar pulse electrodeposition using pre-activated carbon fiber paper as a substrate. The noble metal is one of Ir, Pt, Ru, and Au. The preparation method of the Ni-based noble metal single-atom catalyst includes the following steps: (1) Soak clean hydrophilic carbon paper in nitric acid solution for 30 min, clean it, and then transfer it to sulfuric acid solution for electrochemical activation to obtain pretreated substrate carbon paper. (2) Add nickel metal salt, soluble noble metal ion salt, boric acid, polyvinylpyrrolidone, ammonium chloride and ammonium fluoride to the aqueous solvent, stir thoroughly at room temperature until dissolved, and adjust the pH of the solution to 2.7 with dilute hydrochloric acid; (3) Using the pretreated substrate carbon paper obtained in step (1) as the working electrode, the solution obtained in step (2) was deposited in situ for 8000s in a water bath at 30°C using a unipolar pulse electrodeposition method. The resulting catalyst was washed several times with deionized water and ethanol and then dried under vacuum to obtain a Ni-based noble metal single-atom catalyst.

2. The Ni-based noble metal single-atom catalyst according to claim 1, characterized in that, In step (1), the concentration of HNO3 solution is 1.0M and the concentration of H2SO4 solution is 0.5M.

3. The Ni-based noble metal single-atom catalyst according to claim 1, characterized in that, In step (2), the molar ratio of nickel metal salt to noble metal ion salt is 150~50000.

4. The Ni-based noble metal single-atom catalyst according to claim 1, characterized in that, The concentration of soluble precious metal ion salts is 0.003~1 mmol / L.

5. The Ni-based noble metal single-atom catalyst according to claim 1, characterized in that, In step (2), the concentration of nickel metal salt in the solution is 150 mmol / L, the molar ratio of boric acid to nickel metal salt is 2:15, the concentration of ammonium chloride is 20 mmol / L, the molar ratio of ammonium fluoride to ammonium chloride is 1:15, and the concentration of polyvinylpyrrolidone is 0.01 g / ml.

6. The Ni-based noble metal single-atom catalyst according to claim 1, characterized in that, The potential for unipolar pulse electrodeposition is -2.2V to -1.8V vs. Hg / Hg2SO4, with the Hg / Hg2SO4 electrode serving as the reference electrode; the pulse interval for unipolar pulse electrodeposition is 1s, and the duty cycle for unipolar pulse electrodeposition is 0.

5.

7. The application of a Ni-based noble metal single-atom catalyst as described in claim 1 in alkaline water electrolysis for hydrogen production.

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