Metal-doped nickel-cobalt alloy catalyst as well as preparation method and application thereof

Abstract

The invention discloses a metal-doped nickel-cobalt alloy catalyst as well as a preparation method and application thereof, and belongs to the technical field of electro-catalytic materials. The metal-doped nickel-cobalt alloy catalyst comprises a metal-doped nickel-cobalt alloy material, and doped metal is selected from copper, iron, manganese, chromium or aluminum. The molar ratio of the nickel to the cobalt to the doped metal is 1: (0.1-2): (0.001-0.1); the metal-doped nickel-cobalt alloy material is loaded on the surface of the conductive substrate; the metal-doped nickel-cobalt alloy catalyst is of a wrinkled two-dimensional nanosheet structure and belongs to a face-centered cubic structure. The preparation method comprises the following steps: growing nickel salt, cobalt salt and doped metal salt on the conductive substrate in an electro-deposition manner to obtain the metal-doped nickel-cobalt alloy catalyst. The metal-doped nickel-cobalt alloy catalyst provided by the invention has excellent electro-catalytic performance, and shows relatively low oxidation potential and relatively high formic acid selectivity in glycerol electro-oxidation; the preparation method is simple and easy to implement and easy for expanded production.

Description

Technical Field

[0001] The present invention belongs to the technical field of electrocatalytic materials, and in particular relates to a metal-doped nickel-cobalt alloy catalyst and a preparation method and application thereof. Background Art

[0002] As a sustainable and clean energy source, H 2 It is an essential part of future energy strategies. Water electrolysis is an effective way to produce clean and ultrapure hydrogen. However, the theoretical voltage of water decomposition is 1.23V, which leads to slow reaction kinetics of oxygen evolution reaction at the anode. In addition, the oxygen produced at the anode is also easy to react with H produced at the cathode. 2 Mixing will cause explosion. Using organic matter oxidation instead of oxygen evolution reaction is safe and economical, which can not only reduce the cell pressure, but also produce high value-added chemical products at the anode. Among them, glycerol is a by-product of biodiesel production. One ton of biodiesel can produce about 100kg of glycerol. In recent years, with the rapid development of the biodiesel industry, the output of glycerol has increased year by year, resulting in a sharp drop in the price of glycerol. However, glycerol is an important biomass resource, which can be converted into a variety of high value-added chemical products such as glyceraldehyde, glyceric acid, hydroxymalonic acid, dihydroxyacetone, oxalic acid, lactic acid, glycolic acid and formic acid through oxidation, esterification, etherification, acidification and other processes. Compared with traditional thermal catalysis and microbial fermentation processes, electrocatalysis has many unique advantages in glycerol oxidation. First, the reaction is carried out at room temperature and pressure, which is environmentally friendly; second, the oxidation potential of glycerol is much lower than that of water; finally, the selectivity of the product can be controlled by regulating the catalyst and the electrocatalytic process. However, current research mainly focuses on precious metal catalysts. Considering the cost and benefit, it is more important to develop non-precious metal-based catalysts with excellent glycerol electrooxidation performance. Summary of the invention

[0003] In view of this, the present invention provides a metal-doped nickel-cobalt alloy catalyst and a preparation method and application thereof, the main purpose of which is to solve the technical problem that the catalytic performance of the electrocatalyst needs to be improved.

[0004] In one aspect, the present invention provides a metal-doped nickel-cobalt alloy catalyst, comprising a metal-doped nickel-cobalt alloy material, wherein the doped metal is selected from copper, iron, manganese, chromium or aluminum.

[0005] Optionally, the molar ratio of nickel, cobalt and doping metal in the metal-doped nickel-cobalt alloy material is 1:(0.1-2):(0.001-0.1).

[0006] Optionally, the molar ratio of the cobalt to the nickel is selected from any value among 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, 1.0, 1.1, 1.2, 1.3, 1.4, 1.5, 1.6, 1.7, 1.8, 1.9, 2.0 or any range value therebetween.

[0007] Optionally, the molar ratio of the doping metal to the nickel is selected from any value among 0.001, 0.002, 0.003, 0.004, 0.005, 0.006, 0.007, 0.008, 0.009, 0.01, 0.02, 0.03, 0.04, 0.05, 0.06, 0.07, 0.08, 0.09, 0.1 or any range between two of them.

[0008] Optionally, the metal-doped nickel-cobalt alloy catalyst further includes a conductive substrate; the metal-doped nickel-cobalt alloy material is loaded on the surface of the conductive substrate.

[0009] The mass ratio of the metal-doped nickel-cobalt alloy material to the conductive substrate of the present invention can be adjusted according to actual needs.

[0010] Optionally, the metal-doped nickel-cobalt alloy catalyst has a wrinkled two-dimensional nanosheet structure, and its crystal structure is a face-centered cubic structure.

[0011] The metal-doped nickel-cobalt alloy catalyst provided by the present invention has excellent electrocatalytic performance and exhibits lower oxidation potential and higher formic acid selectivity in glycerol electrooxidation.

[0012] In a second aspect, the present invention provides a method for preparing a metal-doped nickel-cobalt alloy catalyst, the method comprising the following steps:

[0013] Growing a raw material containing nickel salt, cobalt salt and doped metal salt on a conductive substrate by electrodeposition to obtain the metal-doped nickel-cobalt alloy catalyst;

[0014] Wherein, the doped metal salt is selected from copper salt, iron salt, manganese salt, chromium salt or aluminum salt.

[0015] Optionally, the molar ratio of the nickel salt, the cobalt salt and the doping metal salt is 1:(0.1-2):(0.001-0.1).

[0016] Optionally, the molar ratio of the cobalt salt to the nickel salt is selected from any value among 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, 1.0, 1.1, 1.2, 1.3, 1.4, 1.5, 1.6, 1.7, 1.8, 1.9, 2.0 or any range value therebetween.

[0017] Optionally, the molar ratio of the doping metal salt to the nickel salt is selected from any value among 0.001, 0.002, 0.003, 0.004, 0.005, 0.006, 0.007, 0.008, 0.009, 0.01, 0.02, 0.03, 0.04, 0.05, 0.06, 0.07, 0.08, 0.09, 0.1 or any range between two of them.

[0018] Optionally, the electrodeposition process comprises:

[0019] A mixed solution of nickel salt, cobalt salt, doped metal salt and solvent is used as the electrolyte;

[0020] A three-electrode mode is adopted, with a conductive substrate as the working electrode, a counter electrode and a reference electrode, and deposition is carried out in a constant potential manner.

[0021] Optionally, the deposition potential of the electrodeposition is -0.5 to -1.5 V, and the deposition time is 150 to 3600 s.

[0022] Optionally, the nickel salt is a divalent nickel salt.

[0023] Optionally, the divalent nickel salt is selected from nickel chloride and / or nickel sulfate.

[0024] The nickel salt of the present invention can also be selected from other types in the prior art according to actual needs.

[0025] Optionally, the cobalt salt is a divalent cobalt salt.

[0026] Optionally, the divalent cobalt salt is selected from cobalt chloride and / or cobalt sulfate.

[0027] The cobalt salt of the present invention can also be selected from other types in the prior art according to actual needs.

[0028] Optionally, the doping metal salt is a corresponding chloride salt and / or sulfate salt.

[0029] The doped metal salt of the present invention may also be selected from other types in the prior art according to actual needs.

[0030] Optionally, the electrolyte also includes hydrochloric acid.

[0031] Optionally, the hydrochloric acid accounts for 0 to 0.01 of the total volume of the electrolyte.

[0032] Optionally, the conductive substrate is selected from carbon paper, carbon cloth, nickel foam, copper foam, iron foam, copper sheet, iron sheet or nickel sheet.

[0033] The present invention provides a specific implementation method, comprising the following steps:

[0034] Step A: Add nickel salt, cobalt salt and doped metal salt to water in a certain proportion, then add a certain amount of hydrochloric acid and mix well;

[0035] Step B: using the above mixed solution as the electrolyte, adopting a three-electrode mode, using a self-supporting substrate (ie, a conductive substrate) as the working electrode, in conjunction with a counter electrode and a reference electrode, and using a constant potential method to deposit for a certain time.

[0036] In a third aspect, the present invention provides the use of the metal-doped nickel-cobalt alloy catalyst as an electrocatalyst in the electro-oxidation of glycerol to produce formic acid.

[0037] Optionally, in the electro-oxidation process, the metal-doped nickel-cobalt alloy catalyst according to claim 1 or 2 is used as the working electrode, Hg / HgO is used as the reference electrode, a graphite rod is used as the counter electrode, and a mixed solution of 1M potassium hydroxide and 0.1M glycerol is used as the electrolyte.

[0038] Compared with the prior art, the present invention has the following beneficial effects:

[0039] 1) The metal-doped nickel-cobalt alloy catalyst provided by the present invention has excellent electrocatalytic performance and exhibits a lower oxidation potential and a higher formic acid selectivity in the electrooxidation of glycerol.

[0040] 2) The preparation method of the metal-doped nickel-cobalt alloy catalyst provided by the present invention is simple and easy to implement, and easy to expand production. BRIEF DESCRIPTION OF THE DRAWINGS

[0041] Figure 1 The X-ray diffraction (XRD) diagram of Example 1 of the present invention before and after iron doping;

[0042] Figure 2 This is a scanning electron microscope (SEM) image of the manganese-doped nickel-cobalt alloy of Example 2 of the present invention;

[0043] Figure 3 The cyclic voltammetry (LSV) curve of the aluminum-doped nickel-cobalt alloy in 1M KOH and 0.1M glycerol electrolyte of Example 3 of the present invention;

[0044] Figure 4 These are the products of copper-doped nickel-cobalt alloy under different voltages in Example 4 of the present invention. DETAILED DESCRIPTION

[0045] The present application is further described below in conjunction with specific embodiments. The following are only a few embodiments of the present application, and are not intended to limit the present application in any form. Although the present application discloses the following preferred embodiments, they are not intended to limit the present application. Any technician familiar with the profession, without departing from the scope of the technical solution of the present application, using the above disclosed technical content to make some changes or modifications are equivalent to equivalent implementation cases and are within the scope of the technical solution.

[0046] Unless otherwise specified, the raw materials in the examples of the present application were purchased from commercial sources and used directly without any special treatment.

[0047] Unless otherwise specified, the analysis methods in the examples all adopt conventional settings and conventional analysis methods of instruments or equipment.

[0048] The analysis method in the embodiment of the present invention is as follows:

[0049] The linear sweep voltammetry curve was tested using a CHI 760E electrochemical workstation (Shanghai Chenhua Instrument Co., Ltd.) (voltage 0-0.6 V (vs. Hg / HgO), scan rate 10 mV / s, and the electrolyte was a mixed solution of 1 M KOH and 0.1 M glycerol).

[0050] The products were detected by high performance liquid chromatography with 5 mM H 2 SO 4 .

[0051] Example 1 (Iron-doped nickel-cobalt alloy catalyst)

[0052] 20 mL of 0.2 M nickel sulfate, 0.2 M cobalt sulfate, 0.0005 M ferric sulfate and 20 microliters of 2 M hydrochloric acid solution were prepared and stirred evenly as the electrolyte; Ag / AgCl electrode was used as the reference electrode, graphite rod was used as the counter electrode, and carbon paper was used as the working electrode to assemble into a three-electrode system; constant potential was used for deposition, the deposition voltage was -1 V (vs. Ag / AgCl), and the deposition time was 1200 s; after the end, it was rinsed with deionized water and dried at room temperature to obtain an iron-doped nickel-cobalt alloy catalyst.

[0053] Figure 1 The XRD diagram is shown in Figure 2. By comparing the XRD before and after iron doping, it is found that the diffraction peak remains unchanged before and after doping, and is still the diffraction peak of nickel and cobalt, and the crystal structure of the catalyst is a face-centered cubic structure.

[0054] Example 2 (Manganese-doped nickel-cobalt alloy catalyst)

[0055] 20 mL of 0.2 M nickel sulfate, 0.4 M cobalt sulfate, 0.01 M manganese sulfate and 100 microliters of 1 M hydrochloric acid solution were prepared and stirred evenly as an electrolyte; Ag / AgCl electrode was used as a reference electrode, a graphite rod was used as a counter electrode, and a copper sheet was used as a working electrode to assemble into a three-electrode system; deposition was performed in a constant potential manner, the deposition voltage was -1.5 V (vs. Ag / AgCl), and the deposition time was 300 s; after completion, the catalyst was rinsed with deionized water and dried at room temperature to obtain a manganese-doped nickel-cobalt alloy catalyst.

[0056] Figure 2 This is the SEM image of manganese-doped nickel-cobalt alloy. It can be clearly seen from the image that the morphology is a nanosheet structure.

[0057] Example 3 (Aluminum-doped nickel-cobalt alloy catalyst)

[0058] 20 mL of 0.2 M nickel chloride, 0.05 M cobalt chloride, 0.002 M aluminum chloride and 50 microliters of 1 M hydrochloric acid solution were prepared and stirred evenly as an electrolyte; Ag / AgCl electrode was used as a reference electrode, a graphite rod was used as a counter electrode, and nickel foam was used as a working electrode to assemble a three-electrode system; deposition was performed in a constant potential manner, the deposition voltage was -1.2 V (vs. Ag / AgCl), and the deposition time was 600 s; after the completion, the catalyst was rinsed with deionized water and dried at room temperature to obtain an aluminum-doped nickel-cobalt alloy catalyst.

[0059] Example 4 (Copper-doped nickel-cobalt alloy catalyst)

[0060] 20 mL of 0.2 M nickel chloride, 0.1 M cobalt chloride, 0.001 M copper chloride and 10 microliters of 5 M hydrochloric acid solution were prepared and stirred evenly as the electrolyte, the Ag / AgCl electrode was the reference electrode, the graphite rod was the counter electrode, and the nickel foam was the working electrode to assemble into a three-electrode system; the deposition was carried out in a constant potential manner, the deposition voltage was -0.8 V (vs. Ag / AgCl), and the deposition time was 1800 s; after the end, it was rinsed with deionized water and dried at room temperature to obtain a copper-doped nickel-cobalt alloy catalyst.

[0061] Example 5 (Electro-oxidation Application)

[0062] The aluminum-doped nickel-cobalt alloy prepared in Example 3 was used as the working electrode, Hg / HgO was used as the reference electrode, a graphite rod was used as the counter electrode, and a mixed solution of 1 M potassium hydroxide and 0.1 M glycerol was used as the electrolyte; a linear sweep voltammetric curve was tested using a CHI 760E electrochemical workstation (voltage range: 0-0.6 V (vs. Hg / HgO), scan rate: 10 mV / s).

[0063] like Figure 3 As shown, at 10mA / cm 2The voltage at the current density was 1.23 V (vs. RHE), and the doped catalyst obviously showed excellent glycerol electro-oxidation performance.

[0064] Example 6 (Electro-oxidation Application)

[0065] The copper-doped nickel-cobalt alloy prepared in Example 4 was used as the working electrode, Hg / HgO as the reference electrode, a graphite rod as the counter electrode, and a mixed solution of 1 M potassium hydroxide and 0.1 M glycerol as the electrolyte. The time-current curve was tested using a CHI 760E electrochemical workstation, and the voltages were selected to be 1.35, 1.4, 1.45, 1.5, 1.55 and 1.6 V (vs. RHE). The product was quantitatively analyzed by high performance liquid chromatography, and the mobile phase was 5 mM H 2 SO 4 .

[0066] Figure 4 The products and their selectivity obtained under different voltages. It can be seen from the figure that the main product of glycerol electro-oxidation is formic acid, and the selectivity can reach 80%.

[0067] The above are only a few embodiments of the present application and do not constitute any form of limitation to the present application. Although the present application is disclosed as above with preferred embodiments, it is not intended to limit the present application. Any technician familiar with the profession, without departing from the scope of the technical solution of the present application, using the technical content disclosed above to make slight changes or modifications are equivalent to equivalent implementation cases and fall within the scope of the technical solution.

Claims

1. A metal-doped nickel-cobalt alloy catalyst, characterized in that: The metal-doped nickel-cobalt alloy catalyst comprises a metal-doped nickel-cobalt alloy material, and the doped metal is selected from copper, iron, manganese, chromium or aluminum.

2. The metal-doped nickel-cobalt alloy catalyst according to claim 1, characterized in that: The molar ratio of nickel, cobalt and doping metal in the metal-doped nickel-cobalt alloy material is 1:(0.1-2):(0.001-0.1).

3. The metal-doped nickel-cobalt alloy catalyst according to claim 1, characterized in that: The metal-doped nickel-cobalt alloy catalyst also includes a conductive substrate; the metal-doped nickel-cobalt alloy material is loaded on the surface of the conductive substrate.

4. The metal-doped nickel-cobalt alloy catalyst according to claim 1, characterized in that: The metal-doped nickel-cobalt alloy catalyst presents a wrinkled two-dimensional nanosheet structure, and its crystal structure belongs to a face-centered cubic structure.

5. The method for preparing a metal-doped nickel-cobalt alloy catalyst according to any one of claims 1 to 4, characterized in that: The method comprises the following steps: Growing a raw material containing nickel salt, cobalt salt and doped metal salt on a conductive substrate by electrodeposition to obtain the metal-doped nickel-cobalt alloy catalyst; Wherein, the doped metal salt is selected from copper salt, iron salt, manganese salt, chromium salt or aluminum salt.

6. The method for preparing a metal-doped nickel-cobalt alloy catalyst according to claim 5, characterized in that: The molar ratio of the nickel salt, the cobalt salt and the doping metal salt is 1:(0.1-2):(0.001-0.1).

7. The method for preparing a metal-doped nickel-cobalt alloy catalyst according to claim 5, characterized in that: The electrodeposition process includes: A mixed solution of nickel salt, cobalt salt, doped metal salt and solvent is used as the electrolyte; The three-electrode mode is adopted, with the conductive substrate as the working electrode, the counter electrode and the reference electrode, and the deposition is carried out in a constant potential manner; Preferably, the deposition potential of the electrodeposition is -0.5 to -1.5 V, and the deposition time is 150 to 3600 s.

8. The method for preparing a metal-doped nickel-cobalt alloy catalyst according to claim 5, characterized in that: The nickel salt is a divalent nickel salt, and the divalent nickel salt is selected from nickel chloride and / or nickel sulfate; the cobalt salt is a divalent cobalt salt, and the divalent cobalt salt is selected from cobalt chloride and / or cobalt sulfate; the doped metal salt is a corresponding chloride and / or sulfate; Preferably, the electrolyte further comprises hydrochloric acid; the hydrochloric acid accounts for 0 to 0.01 of the total volume of the electrolyte; Preferably, the conductive substrate is selected from carbon paper, carbon cloth, nickel foam, copper foam, iron foam, copper sheet, iron sheet or nickel sheet.

9. Use of the metal-doped nickel-cobalt alloy catalyst according to any one of claims 1 to 4 as an electrocatalyst in the electro-oxidation of glycerol to produce formic acid.

10. The use according to claim 9, characterized in that: In the electro-oxidation process, the metal-doped nickel-cobalt alloy catalyst according to any one of claims 1 to 4 is used as the working electrode, Hg / HgO is used as the reference electrode, a graphite rod is used as the counter electrode, and a mixed solution of 1M potassium hydroxide and 0.1M glycerol is used as the electrolyte.

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