Carbon-nitrogen packaged nickel-based binary metal hydrogen evolution catalyst, preparation method and application

Abstract

The invention discloses a carbon-nitrogen packaged nickel-based binary metal hydrogen evolution catalyst, a preparation method and application, a nickel source, a molybdenum source and foamed nickel are subjected to a hydrothermal reaction, then landfill is carried out through CH4N2O, calcination is carried out at a high temperature in a nitrogen atmosphere, and the carbon-nitrogen packaged nickel-based binary metal hydrogen evolution catalyst is prepared. According to the method, 1 mol / L of KOH is used as an electrolyte, a graphite rod is used as a counter electrode, a reference electrode is Hg / HgO, the carbon-nitrogen packaged nickel-based binary metal hydrogen evolution catalyst is tested, the overpotential is only 44 mV under the current density of 10 mA / cm < 2 > through testing, the catalyst is still excellent in performance under the high current density, and data shows that the overpotential can still be kept within 125 mV under the current density of 100 mA / cm < 2 >.

Description

Technical Field

[0001] The invention relates to the technical field of catalysts, and in particular to a carbon-nitrogen encapsulated nickel-based binary metal hydrogen evolution catalyst, a preparation method and an application thereof. Background Art

[0002] Hydrogen is considered a promising way to deal with the energy crisis due to its high energy density and environmentally friendly characteristics. Alkaline water electrolysis can achieve efficient and high-purity hydrogen production. Transition metal electrocatalysts are relatively stable in alkaline solutions and show good catalytic activity in hydrogen evolution reactions.

[0003] At present, platinum-based catalysts have excellent catalytic performance in the hydrogen evolution reaction of alkaline water electrolysis, but their high price limits the large-scale application of this catalyst. Therefore, it is particularly important to develop stable, high-performance, and low-cost hydrogen evolution catalysts. Summary of the invention

[0004] Based on the technical problems existing in the background technology, the present invention proposes a carbon-nitrogen encapsulated nickel-based binary metal hydrogen evolution catalyst, a preparation method and an application thereof. The catalyst is 2 It has an extremely low hydrogen evolution overpotential (44 mV) at a current density of 2.5 wt %. It also has the advantages of good stability, easy preparation, low cost and no pollution.

[0005] The invention provides a method for preparing a carbon-nitrogen encapsulated nickel-based binary metal hydrogen evolution catalyst, and the method comprises the following steps: performing a hydrothermal reaction on a nickel source, a molybdenum source and nickel foam, then filling with CH4N2O, and calcining at a high temperature and in a nitrogen atmosphere to obtain a carbon-nitrogen encapsulated nickel-based binary metal hydrogen evolution catalyst.

[0006] Preferably, the nickel source is NiCl2·6H2O or Ni(NO3)2·6H2O, and the molybdenum source is (NH4)6Mo7O 24 ·4H2O.

[0007] Preferably, the molar ratio of the nickel source to the molybdenum source is 1:1-5.

[0008] Preferably, the temperature of the hydrothermal reaction is 80-200° C., and the reaction time is 2-10 h.

[0009] Preferably, the coverage of CH4N2O is 50-500 mg / cm 2 .

[0010] Preferably, the calcination temperature is 500-1000° C., the calcination time is 1-5 h, and the heating rate is 1-10° C. / min.

[0011] The invention provides a carbon-nitrogen encapsulated nickel-based binary metal hydrogen evolution catalyst prepared by the method.

[0012] The present invention provides an application of the carbon-nitrogen encapsulated nickel-based binary metal hydrogen evolution catalyst in the electrolysis of water for hydrogen evolution reaction.

[0013] Mechanism of action

[0014] The carbon-nitrogen encapsulated nickel-based binary metal hydrogen evolution catalyst prepared by the present invention has a special morphology. Figure 3 It can be seen that the morphology after hydrothermal treatment is in the shape of microrods, while after calcination with CH4N2O for covering and filling, the morphology is in the shape of strip honeycomb porous type. This is because during calcination, the high temperature environment causes the microrod structure formed after hydrothermal treatment to break and cover the surface of nickel foam. The NH4 and CO2 generated by the pyrolysis of CH4N2O filled under the nickel foam overflow upward, causing the catalyst covered on the surface of nickel foam to present a strip honeycomb porous type. In addition, from Figure 2 It can be seen from the XRD that after calcination, the fracture of the microrod catalyst and the stamping of NH4 and CO2 gases form amorphous NiO on the surface of the nickel foam. Compared with the crystalline structure, the amorphous structure has lower hardness, larger specific surface area and better chemical stability. In particular, it contains a large number of randomly oriented chemical bonds and surface exposed defects, which can significantly increase the number of active sites and optimize the adsorption and desorption of reactants. Therefore, compared with the microrods, the morphology after calcination has excellent stability while ensuring a larger catalytic active area.

[0015] Beneficial technical effects of the present invention:

[0016] The present invention uses nickel foam as a substrate, which has high conductivity, and due to its special three-dimensional porous structure, it can load more catalysts, so that Ni and Mo grow on the nickel foam. Both metals have low hydrogen adsorption Gibbs free energy. The synergistic effect between Ni and Mo can adsorb hydrogen atoms and transfer the charge in time to form hydrogen. Then, through carbon-nitrogen encapsulation, it forms a stable alloy structure and optimizes its electronic structure to improve the efficiency of hydrogen evolution reaction. Using 1 mol / L KOH as electrolyte, graphite rod as counter electrode, and Hg / HgO as reference electrode, the carbon-nitrogen encapsulated nickel-based binary metal hydrogen evolution catalyst is tested. The test shows that at 10 mA / cm 2 At a current density of 100 mA / cm, the overpotential is only 44 mV. The catalyst still performs well at high current density. 2 At a current density of 1.5 %, the overpotential can still be maintained within 125 mV. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 The XRD spectrum of the carbon-nitrogen encapsulated nickel-based binary metal hydrogen evolution catalyst prepared in Example 3 of the present invention;

[0018] Figure 2 This is a scanning electron microscope image of the carbon-nitrogen encapsulated nickel-based binary metal hydrogen evolution catalyst prepared in Example 3 of the present invention after hydrothermal treatment and calcination;

[0019] Figure 3 Comparison of linear sweep voltammetric curves of the carbon-nitrogen encapsulated nickel-based binary metal hydrogen evolution catalyst proposed in the present invention;

[0020] Figure 4 The carbon-nitrogen encapsulated nickel-based binary metal hydrogen evolution catalyst proposed in the present invention is subjected to a current density of 10 mA / cm 2 Overpotential comparison when

[0021] Figure 5 It is a test curve diagram of the stability test of water electrolysis hydrogen evolution by the carbon-nitrogen encapsulated nickel-based binary metal hydrogen evolution catalyst prepared in Example 3 proposed by the present invention;

[0022] Figure 6 Comparison of hydrogen evolution polarization curves of the carbon-nitrogen encapsulated nickel-based binary metal hydrogen evolution catalyst prepared in Example 3 of the present invention before and after stability testing. DETAILED DESCRIPTION

[0023] The present invention will be further explained below in conjunction with specific embodiments.

[0024] Example 1

[0025] The method for preparing the carbon-nitrogen encapsulated nickel-based binary metal hydrogen evolution catalyst proposed by the present invention comprises the following steps:

[0026] S1: Cut 2×4cm 2 Foamed nickel was ultrasonicated for 20 min using 4 mol / L HCL, deionized water, and anhydrous ethanol in turn;

[0027] S2: drying the nickel foam treated by S1 in a vacuum drying oven;

[0028] S3: Weigh 1.48g NiCl2·6H2O and 0.59g (NH4)6Mo7O 24 4H2O, and dissolve in 70ml of deionized water, stirring for 10min;

[0029] S4: The mixed solution of S3 was transferred to a 100 ml hydrothermal reactor, and the nickel foam obtained from the drying of S2 was placed vertically, and the reaction was carried out at a temperature of 150°C for 6 hours;

[0030] S5: Rinse the nickel foam after the reaction in step 4 with deionized water, and dry it in a vacuum drying oven at 60° C. for 30 min;

[0031] S6: Lay a layer of CH4N2O on the bottom of the porcelain boat, place the foamed nickel in step 5 flat on the CH4N2O, and fill the foamed nickel with CH4N2O until it is completely covered, then put the porcelain boat into a tubular furnace, and heat the temperature from room temperature to 750°C at a heating rate of 5°C / min under a nitrogen atmosphere, and maintain this temperature for 2h, finally obtaining a carbon-nitrogen encapsulated nickel-based binary metal hydrogen evolution catalyst.

[0032] Example 2

[0033] The method for preparing the carbon-nitrogen encapsulated nickel-based binary metal hydrogen evolution catalyst proposed by the present invention comprises the following steps:

[0034] S1: Cut 2×4cm 2 Foamed nickel was ultrasonicated for 20 min using 4 mol / L HCL, deionized water, and anhydrous ethanol in turn;

[0035] S2: drying the nickel foam treated by S1 in a vacuum drying oven;

[0036] S3: Weigh 0.986g NiCl2·6H2O and 0.778g (NH4)6Mo7O 24 4H2O, and dissolve in 70ml of deionized water, stirring for 10min;

[0037] S4: The mixed solution of S3 was transferred to a 100 ml hydrothermal reactor, and the nickel foam obtained from the drying of S2 was placed vertically, and the reaction was carried out at a temperature of 150°C for 6 hours;

[0038] S5: Rinse the nickel foam after the reaction in step 4 with deionized water, and dry it in a vacuum drying oven at 60° C. for 30 min;

[0039] S6: Lay a layer of CH4N2O on the bottom of the porcelain boat, place the foamed nickel in step 5 flat on the CH4N2O, and fill the foamed nickel with CH4N2O until it is completely covered, then put the porcelain boat into a tubular furnace, and heat the temperature from room temperature to 750°C at a heating rate of 5°C / min under a nitrogen atmosphere, and maintain this temperature for 2h, finally obtaining a carbon-nitrogen encapsulated nickel-based binary metal hydrogen evolution catalyst.

[0040] Example 3

[0041] The method for preparing the carbon-nitrogen encapsulated nickel-based binary metal hydrogen evolution catalyst proposed by the present invention comprises the following steps:

[0042] S1: Cut 2×4cm 2 Foamed nickel was ultrasonicated for 20 min using 4 mol / L HCL, deionized water, and anhydrous ethanol in turn;

[0043] S2: drying the nickel foam treated by S1 in a vacuum drying oven;

[0044] S3: Weigh 0.74g NiCl2·6H2O and 0.89g (NH4)6Mo7O 24 4H2O, and dissolve in 70ml of deionized water, stirring for 10min;

[0045] S4: The mixed solution of S3 was transferred to a 100 ml hydrothermal reactor, and the nickel foam obtained from the drying of S2 was placed vertically, and the reaction was carried out at a temperature of 150°C for 6 hours;

[0046] S5: Rinse the nickel foam after the reaction in step 4 with deionized water, and dry it in a vacuum drying oven at 60° C. for 30 min;

[0047] S6: Lay a layer of CH4N2O on the bottom of the porcelain boat, place the foamed nickel in step 5 flat on the CH4N2O, and fill the foamed nickel with CH4N2O until it is completely covered, then put the porcelain boat into a tubular furnace, and heat the temperature from room temperature to 750°C at a heating rate of 5°C / min under a nitrogen atmosphere, and maintain this temperature for 2h, finally obtaining a carbon-nitrogen encapsulated nickel-based binary metal hydrogen evolution catalyst.

[0048] Example 4

[0049] The method for preparing the carbon-nitrogen encapsulated nickel-based binary metal hydrogen evolution catalyst proposed by the present invention comprises the following steps:

[0050] S1: Cut 2×4cm 2 Foamed nickel was ultrasonicated for 20 min using 4 mol / L HCL, deionized water, and anhydrous ethanol in turn;

[0051] S2: drying the nickel foam treated by S1 in a vacuum drying oven;

[0052] S3: Weigh 0.13g NiCl2·6H2O and 0.51g (NH4)6Mo7O 24 4H2O, and dissolve in 70ml of deionized water, stirring for 10min;

[0053] S4: The mixed solution of S3 was transferred to a 100 ml hydrothermal reactor, and the nickel foam obtained from the drying of S2 was placed vertically, and the reaction was carried out at a temperature of 150°C for 6 hours;

[0054] S5: Rinse the nickel foam after the reaction in step 4 with deionized water, and dry it in a vacuum drying oven at 60° C. for 30 min;

[0055] S6: Lay a layer of CH4N2O on the bottom of the porcelain boat, place the foamed nickel in step 5 flat on the CH4N2O, and fill the foamed nickel with CH4N2O until it is completely covered, then put the porcelain boat into a tubular furnace, and heat the temperature from room temperature to 750°C at a heating rate of 5°C / min under a nitrogen atmosphere, and maintain this temperature for 2h, finally obtaining a carbon-nitrogen encapsulated nickel-based binary metal hydrogen evolution catalyst.

[0056] The carbon-nitrogen encapsulated nickel-based binary metal hydrogen evolution catalyst prepared by the present invention was tested for electrochemical performance using a three-electrode system on a CHI760E electrochemical workstation. The test conditions were 1 mol / L KOH as the electrolyte, the prepared catalyst as the working electrode, the graphite rod as the counter electrode, and the reference electrode as Hg / HgO.

[0057] Figure 1 This is the XRD spectrum of the catalyst prepared in Example 3. It can be seen from the figure that after the catalyst was calcined, amorphous NiO was successfully formed.

[0058] Figure 2 This is a scanning electron microscope image of the catalyst prepared in Example 3. It can be seen from the image that the catalyst has a strip-like honeycomb porous morphology.

[0059] Figure 3 The linear sweep voltammetric curves of the catalysts prepared in Examples 1-4 are compared. It can be seen from the figure that at 85 mA / cm 2 At a current density of , Example 3 still has an extremely low overpotential of 123 mV.

[0060] Figure 4 The catalyst prepared in Example 1-4 was subjected to a current density of 10 mA / cm 2 As can be seen from the figure, the four ratios all have extremely low overpotentials, among which Example 2 is the best, which is only 48mV, followed by Example 3, which is 56mV.

[0061] Figure 5 This is an IT stability test diagram of the catalyst prepared in Example 3. It can be seen from the figure that the carbon-nitrogen encapsulation / Ni-Mo / nickel foam binary metal hydrogen evolution catalyst can continuously and stably operate for at least 15 hours for hydrogen evolution by electrolysis of water.

[0062] Figure 6 This is a comparison diagram of the linear sweep voltammogram of the carbon-nitrogen encapsulation / Ni-Mo / nickel foam binary metal hydrogen evolution catalyst prepared in Example 3 before and after electrolysis of water for hydrogen evolution for 15 hours. It can be seen from the figure that after the catalyst has been running continuously for 15 hours, the overpotential at high current density is basically unchanged.

Claims

1. A method for preparing a carbon-nitrogen encapsulated nickel-based binary metal hydrogen evolution catalyst, characterized in that: The method comprises the following steps: performing hydrothermal reaction on a nickel source, a molybdenum source and nickel foam, then filling with CH4N2O, and calcining under high temperature and nitrogen atmosphere to prepare a carbon-nitrogen encapsulated nickel-based binary metal hydrogen evolution catalyst.

2. The method for preparing the carbon-nitrogen encapsulated nickel-based binary metal hydrogen evolution catalyst according to claim 1, characterized in that: The nickel source is NiCl2·6H2O or Ni(NO3)2·6H2O, and the molybdenum source is (NH4)6Mo7O 24 ·4H2O.

3. The method for preparing the carbon-nitrogen encapsulated nickel-based binary metal hydrogen evolution catalyst according to claim 1, characterized in that: The molar ratio of the nickel source to the molybdenum source is 1:1-5.

4. The method for preparing the carbon-nitrogen encapsulated nickel-based binary metal hydrogen evolution catalyst according to claim 1, characterized in that: The temperature of the hydrothermal reaction is 80-200°C, and the reaction time is 2-10h.

5. The method for preparing the carbon-nitrogen encapsulated nickel-based binary metal hydrogen evolution catalyst according to claim 1, characterized in that: The coverage of CH4N2O is 50-500mg / cm 2 .

6. The method for preparing the carbon-nitrogen encapsulated nickel-based binary metal hydrogen evolution catalyst according to claim 1, characterized in that: The calcination temperature is 500-1000°C, the calcination time is 1-5h, and the heating rate is 1-10°C / min.

7. A carbon-nitrogen encapsulated nickel-based binary metal hydrogen evolution catalyst prepared by the method according to any one of claims 1 to 6.

8. Use of the carbon-nitrogen encapsulated nickel-based binary metal hydrogen evolution catalyst as claimed in claim 7 in hydrogen evolution reaction by electrolysis of water.

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