CN110459775A - Inorganic light element doped nickel-based material and its preparation method and application - Google Patents

Abstract

The invention discloses a method for preparing a nickel-based material doped with inorganic light elements, comprising the following steps: S1, providing a nickel precursor material; S2, hydrogenating, boriding, carbonizing or nitriding the nickel precursor material, namely The nickel-based material doped with inorganic light elements is obtained; wherein, the nickel precursor material includes nickel salt, nickel complex, inorganic nickel precursor material and nickel metal organic framework material. The invention also provides the inorganic light element-doped nickel-based material prepared by the method, and its application as an electrocatalyst for hydrogen oxidation reaction/hydrogen evolution reaction. The nickel-based material doped with inorganic light elements of the present invention has excellent hydrogen electrocatalytic activity, good stability and the ability to resist carbon monoxide poisoning; and is low in cost and simple in preparation, so it has wide commercial application prospects.

Description

Inorganic light element doped nickel-based material and its preparation method and application

technical field

The invention relates to the technical field of electrocatalysis and energy conversion, in particular to a nickel-based material doped with inorganic light elements, its preparation method and its application as an electrocatalyst for hydrogen oxidation reaction/hydrogen evolution reaction.

Background technique

As a clean and efficient energy source, hydrogen has extremely high application value in modern industrial fields. The development of hydrogen economy mainly includes two aspects involving two semi-electrochemical reactions: hydrogen storage-hydrogen oxidation reaction and hydrogen utilization-hydrogen evolution reaction, such as hydrogen-oxygen fuel cells and electrolysis of water. Due to the slow kinetics of the hydrogen oxidation reaction/hydrogen evolution reaction, it is necessary to develop electrochemical catalysts to accelerate the reaction rate. At present, platinum-based catalysts exhibit good hydrogen electrocatalytic activity, but the scarcity and high price of noble metal resources prevent their large-scale commercial application. In addition, platinum-based catalysts are easily poisoned by carbon monoxide. Therefore, the use of non-platinum catalysts to promote the electrochemical reaction of hydrogen is of great significance for realizing the hydrogen economy.

In order to develop non-noble metal oxygen reduction catalysts in alkaline systems, alkaline polymer electrolyte fuel cells came into being. Unfortunately, the platinum-based catalysts with the best hydrogen electrocatalytic activity under alkaline conditions are two orders of magnitude less active for hydrogen oxidation/hydrogen evolution than those under acidic conditions, requiring higher loadings. It is a serious challenge to develop cheap and efficient non-platinum catalysts in alkaline systems.

In alkaline systems, some non-platinum hydrogen evolution catalysts have been discovered, but hydrogen oxidation catalysts are rarely reported. Nickel is the only non-noble metal with hydrogen oxidation activity, and the earliest Raney nickel appeared far away from platinum-based catalysts due to its strong surface hydrogen binding energy. Metal doping and support carrier effects can effectively reduce the hydrogen binding energy on the nickel surface. For example, nickel-transition metal (transition metals are chromium, molybdenum, copper, iron, zinc, etc.) cobalt-nickel-molybdenum is an efficient hydrogen oxidation catalyst, and carbon-nitrogen co-doped nickel also shows good hydrogen oxidation activity. However, there is still a gap in the activity of nickel-based materials compared to platinum.

Contents of the invention

In order to improve the catalytic activity, stability and resistance to carbon monoxide poisoning of non-noble metals in alkaline systems, the present invention proposes a nickel-based material doped with inorganic light elements, which is used as an alkaline and neutral It is an electrocatalyst for hydrogen oxidation reaction/hydrogen evolution reaction, which has excellent hydrogen electrocatalytic activity, good stability and the ability to resist carbon monoxide poisoning; as a non-noble metal nickel-based material, the interstitial doped nickel-based material is low in cost and easy to prepare. Therefore, it has broad commercial application prospects.

In order to solve the above technical problems, the invention provides a method for preparing an inorganic light element nickel-based material, comprising the following steps:

S1. Provide nickel precursor materials;

S2. Hydrogenating, boriding, carbonizing or nitriding the nickel precursor material to obtain the nickel-based material;

Wherein, the nickel precursor material includes nickel salt, nickel complex, inorganic nickel precursor material and nickel metal organic framework material.

Further, the nickel precursor material includes commercially bought nickel salts such as nickel nitrate, nickel sulfate, nickel acetate, and nickel halide; nickel complexes such as ammonia complexes, cyanide complexes, carbonyl complexes, and chelates materials; inorganic nickel precursor materials such as nickel oxide and nickel hydroxide that can be obtained after preparation; and nickel metal organic framework materials formed by coordination of organic ligands such as isophthalic acid and terephthalic acid with metallic nickel.

Further, the nickel precursor material can be hydrogenated, boronated, carbonized or nitrided by high temperature calcination method or direct introduction method. Among them, the nitriding/hydrogenation/boration process can adopt the direct introduction method, specifically, adding ammonia water, dicyandiamide, ammonium chloride, etc. to the solution before the nickel precursor is formed to directly introduce nitrogen/hydrogen/boron Wait for small molecules.

Further, the introduced hydrogen source includes hydrogen, ammonia and hydrogen peroxide; the introduced boron source includes borax, sodium borohydride and boric acid; the introduced carbon source includes methane, ethane, carbon monoxide and other carbon-rich gases, urea, graphite, etc. Solid carbon materials, and carbon-containing organic ligand materials such as isophthalic acid and terephthalic acid; nitrogen sources introduced include urea, ammonium chloride, dicyandiamide, ammonium hydroxide, ammonia and nitrogen.

Further, during the preparation process of nickel-based materials, transition metal elements can also be added to adjust the electronic state of nickel, and the transition metal elements can be one of iron, copper, zinc, chromium, manganese, cobalt, molybdenum and other metals or several.

Furthermore, the high-temperature calcination temperature required for doping different elements is different, and the calcination temperature is preferably 300-600° C., and the calcination temperature and time determine the degree of material doping.

Furthermore, a conductive agent can also be added during the preparation of the nickel-based material to improve the conductivity of the material. The conductive agent can be Ketjen black, acetylene black, carbon nanotube, carbon fiber, carbon black conductive agent such as Super P, Super S, 350G, graphite conductive agent such as KS-6, KS-15, SFG-6, SFG-15, etc. agent or graphene.

Furthermore, a surfactant can also be added during the preparation of the nickel-based material to adjust the size and morphology of the material. Described surfactant comprises cationic surfactants such as cetyltrimethylammonium bromide, cetyltrimethylammonium chloride, dodecyltrimethylammonium bromide; Sodium citrate, poly Non-ionic surfactants such as ethylene glycol octylphenyl ether, polyoxyethylene sorbitan fatty acid ester; sodium dodecylsulfonate, sodium dodecylsulfate, sodium dodecylbenzenesulfonate Anionic surfactants such as polyvinylpyrrolidone, carboxymethyl cellulose, and carbopol; and amphoteric surfactants such as imidazoline derivatives, betaine, and sulfobetaine.

Another aspect of the present invention also provides the nickel-based material prepared by the method. Since hydrogen, boron, carbon, nitrogen inorganic light elements or transition metal elements such as iron, cobalt, copper, zinc, chromium, molybdenum, and tungsten enter the nickel lattice to form heteroatom-doped nickel-based materials, greatly reducing the hydrogen content on the nickel surface The binding energy is beneficial to the conduction of hydroxide in the alkaline electrolyte, thereby improving the activity of the catalyst, and it also has a certain hydrogen oxidation activity under neutral conditions.

Further, the shape of the nickel-based material may be nanoparticles, nanosheets, nanospheres, nanorods, nanowires or nanotubes.

The present invention also provides the above-mentioned molecule-doped nickel-based material as a catalyst for hydrogen oxidation reaction and hydrogen evolution reaction under alkaline or neutral conditions.

Further, the molecularly doped nickel-based material can be loaded on electrode substrate materials to evaluate its hydrogen electrocatalytic performance, and the substrate materials include glassy carbon electrodes, carbon paper, gas diffusion electrodes, metal foam electrodes, metal foil electrodes, etc.

Beneficial effects of the present invention:

1. The present invention proposes for the first time a nickel-based material doped with inorganic light elements such as hydrogen, boron, carbon, and nitrogen or transition metal elements such as iron, cobalt, copper, zinc, manganese, chromium, molybdenum, and tungsten as a hydrogen oxidation reaction catalyst. At the same time, it has excellent catalytic hydrogen evolution reaction activity. Compared with the non-precious metal nickel as a hydroxide catalyst in the existing alkaline system, the activity is greatly improved, and it can even catch up with the most active noble metal platinum under double load. electric potential. And it also has a certain hydrogen oxidation activity under neutral conditions.

2. The quality of nickel-based materials doped with transition metal elements such as inorganic light elements hydrogen, boron, carbon, and nitrogen doped with iron, cobalt, copper, zinc, manganese, chromium, molybdenum, and tungsten prepared by the present invention to catalyze hydrogen oxidation reaction quality Very active. At the same time, the nickel nitride catalyst prepared by the invention exhibits better hydrogen evolution activity. Its catalytic activity far exceeds other existing non-precious metal hydrogen electrocatalysts, which can alleviate the pressure of scarce precious metal resources, and the nickel nitride provided by the invention has a simple preparation process, which can greatly reduce the cost of fuel cells. It has strong application value.

3. The nickel-based catalysts prepared by the present invention doped with inorganic light elements such as hydrogen, boron, carbon, and nitrogen or doped with transition metal elements such as iron, cobalt, copper, zinc, manganese, chromium, molybdenum, and tungsten are effective in hydrogen oxidation reaction and During the hydrogen evolution reaction, it exhibited good stability and strong resistance to carbon monoxide poisoning. When carbon monoxide was injected during the stability test, the activity of metallic platinum decreased significantly while that of nickel nitride decreased almost negligibly. Its excellent resistance to carbon monoxide poisoning makes it have higher commercial application value, solves the problem of reduced efficiency of carbon monoxide poisoning in proton exchange membrane fuel cells and direct methanol fuel cells, and is expected to replace the most active noble metals in the field of hydrogen electrocatalysis platinum.

Description of drawings

Fig. 1 is the TEM image (a, b) and the XRD image (c) of the nickel coordination polymer in embodiment 1;

Fig. 2 is the XRD image (a), SEM image (b) and TEM image (c) of the nickel nitride nanoparticle in embodiment 1;

3 is a polarization curve (left) and a hydrogen evolution reaction polarization curve (right) of nickel nitride nanoparticles in Example 1 catalytic hydrogen oxidation reaction at different rotation speeds;

Fig. 4 is the anti-carbon monoxide poisoning stability curve figure of nickel nitride nanoparticles and noble metal platinum in embodiment 1;

FIG. 5 is a polarization curve of hydrogen evolution reaction catalyzed by nickel nitride nanoparticles, metal nickel nanoparticles and noble metal platinum in Example 1. FIG.

Detailed ways

The present invention will be further described below in conjunction with the accompanying drawings and specific embodiments, so that those skilled in the art can better understand the present invention and implement it, but the examples given are not intended to limit the present invention.

The following examples use different nickel precursors to obtain nitrogen, hydrogen, carbon and other inorganic light elements doping or iron, cobalt, copper, zinc, manganese, chromium, molybdenum, tungsten and other transition metal elements through nitriding/hydrogenation/carbonization methods Doped nickel nanomaterials. The catalyst is loaded on a glassy carbon electrode to test the activity of hydrogen oxidation and hydrogen evolution. The electrolyte is 0.1M potassium hydroxide. Under the three-electrode system, the carbon rod is used as the counter electrode, and the saturated calomel electrode is used as the reference electrode. The slurry coating The conductive substrate was used as the working electrode to test the hydrogen oxidation and hydrogen evolution polarization curves. The sweep speeds of linear sweep voltammetry curves for hydrogen oxidation and hydrogen evolution were 1mV/s and 5mV/s, respectively, and the electrochemical compensation was 95%. The poisoning gas adopts 5% CO/N ₂ mixed gas.

Slurry preparation: Weigh 2 mg of nickel nanomaterials and 0.3 mg of Ketjen Black, add 200 μL of ethanol and 8 μL of naphthol to prepare catalyst slurry, drop 10 μL and 20 μL on the glassy carbon electrode respectively, and let it dry naturally in the air.

Electrochemical test process:

(1) Hydrogen oxidation performance test: Before the test, inject hydrogen gas into the 0.1M potassium hydroxide electrolyte for 30 minutes to saturation, keep the hydrogen gas continuously injected during the test, scan CV for a period of time under the three-electrode system, and then test Linear sweep voltammetry curves of electrochemically compensated 95% hydrogen oxidation at different rotational speeds.

(2) Hydrogen evolution performance test: Before the test, nitrogen gas was passed into 1M potassium hydroxide for 30 minutes, and the air was discharged. During the test, nitrogen gas was continuously passed on the liquid surface, and the linear sweep voltammetry curve was tested at 1600 rpm, the sweep rate was 5 mV/s, and the electrochemical compensation was 95%.

Example 1: Synthesis of nickel nitride with nickel coordination polymer as precursor

Dissolve 0.6mmol nickel nitrate hexahydrate and 0.3g polyvinylpyrrolidone in 20mL deionized water to obtain solution A, dissolve 0.4mmol nickel potassium cyanide in 20mL deionized water to obtain precipitant B, put solution A on a stirrer and stir vigorously for 5min , slowly drop into the precipitant B, after the dropwise addition, continue to stir for 2min, then stand at room temperature for aging for 24h, centrifuge, wash, and vacuum freeze-dry to obtain the nickel coordination polymer precursor, place the nickel coordination polymer in a vacuum tube Calcined in an ammonia atmosphere at 450°C for 1 h to prepare nickel nitride nanoparticles.

It can be seen from Figure 1 that the nickel coordination polymer is a square sheet with irregular shape of 100-200nm. It can be seen from Fig. 2 that after high-temperature ammoniation, the nickel square sheet is broken to obtain a small amount of nickel nitride nanoparticles wrapped in carbon layer. These nickel nitride nanoparticles are uniformly distributed, with an average size of 12.5nm and an average diameter of about 10-20nm. Nitrogen enters the nickel lattice to form nickel nitride, which greatly reduces the hydrogen binding energy on the nickel surface. In addition, the nickel nitride nanoparticles under the protection of the carbon layer are extremely difficult to be oxidized in the air, making the nitrogen-doped nickel catalyst It has ultra-high hydrogen electrocatalytic activity and good stability. A small amount of carbon layer plays the role of supporting carrier while increasing the conductivity, which is beneficial to the conduction of hydroxide in the alkaline electrolyte, thereby improving the activity of the catalyst.

Figure 3 shows the hydrogen oxidation and hydrogen evolution polarization curves of nickel nitride nanoparticles. It can be seen that nickel nitride nanoparticles have ultra-high catalytic activity for hydrogen oxidation and hydrogen evolution. For hydrogen oxidation, when the rotating speed is 1600rpm, the current density can reach 1.7mA cm _disk ^-2 at 50mV. For hydrogen evolution, when the current density is 10mA cm ^-2 , the required overpotential is only 68mV.

Referring to FIG. 4 , compared with the noble metal platinum, the nickel nitride nanoparticles in Example 1 always maintain a stronger ability to resist carbon monoxide poisoning.

It can be seen from FIG. 5 that the nickel nitride nanoparticles in Example 1 exhibit good stability during the hydrogen evolution reaction.

Example 2: Synthesis of carbon-doped nickel using Ni-MOF74 as a precursor

Weigh 0.043g 2,5-dihydroxyterephthalic acid, 0.13g nickel nitrate, 0.007g salicylic acid, and 45ml of reaction kettle, in 18ml of ethanol:N,N-dimethylformamide:water=1 : 1:1 solution ultrasonically dissolved completely. The reaction kettle was placed in an oven at 120°C for 8 hours, centrifuged, washed, and vacuum-dried to obtain the Ni-MOF74 precursor. Ni-MOF74 was placed in a vacuum tube furnace and calcined at 450 °C for 1 h in an argon atmosphere to prepare carbon-doped nickel nanomaterials.

Example 3: Using nickel hydroxide as a precursor to synthesize hydrogen-doped nickel

Dissolve 4mmol of nickel nitrate in 10ml of deionized water, add 5ml of ammonia water to obtain a soluble nickel-ammonia complex, quickly transfer the nickel-ammonia complex to 45ml of diethylene glycol, and put it in an oil bath at 100°C for 30min to make the ammonia gas Released to obtain a nickel hydroxide precursor. The nickel hydroxide precursor was calcined at 350°C for 1 h in a hydrogen atmosphere to prepare hydrogen-doped nickel hydride nanomaterials.

The above-mentioned embodiments are only preferred embodiments for fully illustrating the present invention, and the protection scope of the present invention is not limited thereto. Equivalent substitutions or transformations made by those skilled in the art on the basis of the present invention are all within the protection scope of the present invention. The protection scope of the present invention shall be determined by the claims.

Claims (10)

1. a kind of preparation method of light inorganic element doping nickel-base material, which comprises the following steps:

S1, nickel persursor material is provided；

S2, make the nickel persursor material hydrogenation, boronation, carbonization or nitridation to get the nickel-base material for arriving the doping；

Wherein, the nickel persursor material includes nickel salt, nickel complex, inorganic nickel persursor material and nickel metal organic frame Material.

2. the preparation method of nickel-base material as described in claim 1, which is characterized in that the nickel salt include nickel nitrate, nickel sulfate, Nickel acetate, nickel halogenide；The nickel complex include the ammino compound of nickel, cyanogen complex, carbonyl complex with And chelate；The inorganic nickel presoma includes nickel oxide, nickel hydroxide；The nickel metal-organic framework material includes isophthalic three Formic acid, terephthalic acid (TPA) and metallic nickel are coordinated the organic framework materials to be formed.

3. the preparation method of nickel-base material as described in claim 1, which is characterized in that in step S2, using high-temperature calcination Or direct introduction method makes the nickel persursor material hydrogenation, boronation, carbonization or nitridation；

The hydrogen source of introducing includes hydrogen, ammonia, hydrogen peroxide；The boron source of introducing includes borax, sodium borohydride, boric acid；It introduces Carbon source includes carbon-rich gas, solid carbonaceous material, carbon containing organic ligand material；The nitrogen source of introducing includes urea, ammonium chloride, double cyanogen Amine, ammonium hydroxide, ammonia, nitrogen；

Wherein, the carbon-rich gas includes methane, ethane, carbon monoxide；The solid carbonaceous material includes urea, graphite；It is described Carbon containing organic ligand material includes 1,3,5-Benzenetricarboxylic acid and terephthalic acid (TPA).

4. the preparation method of nickel-base material as claimed in claim 3, which is characterized in that the nickel-base material is gone back during the preparation process Transition metal element is added, the transition metal element is selected from one of iron, cobalt, copper, zinc, chromium, manganese, molybdenum, tungsten or a variety of.

5. the preparation method of nickel-base material as claimed in claim 4, which is characterized in that the temperature of high-temperature calcination is 300~600 ℃。

6. the preparation method of nickel-base material as described in claim 1, which is characterized in that the nickel-base material is during the preparation process It is also added into conductive agent, the conductive agent is selected from least one of carbon black conductive agent, graphite agent, graphene.

7. the preparation method of nickel-base material as described in claim 1, which is characterized in that the nickel-base material is during the preparation process It is also added into surfactant.

8. the nickel-base material that method according to claim 1-7 is prepared.

9. nickel-base material as claimed in claim 8, which is characterized in that the nickel-base material is nano particle, nanometer sheet, nanometer Ball, nanometer rods, nano wire or nanotube.

10. nickel-base material as claimed in claim 9 is urged as the alkaline oxidation of hydrogen under neutrallty condition and hydrogen evolution reaction Agent.