阅读说明：本技术 一种Ni/C核壳结构纳米材料电催化剂及其制备方法 (Ni/C core-shell structure nano material electrocatalyst and preparation method thereof ) 是由 高鹏 贾东梅 于 2020-12-10 设计创作，主要内容包括：本发明涉及催化剂技术领域,针对现有电催化剂催化析氢催化效率低的问题,公开了一种Ni/C核壳结构纳米材料电催化剂及其制备方法,包括以下步骤：步骤一：将六水合氯化镍溶解在蒸馏水中,形成第一溶液；步骤二：将氨乙酸和异丙醇加入到上述第一溶液中,形成第二溶液；步骤三：将上述第二溶液搅拌成悬浊液,将悬浊液转入到容器中,梯度加热反应后冷却至室温,得到浅绿色沉淀；步骤四：将收集到的浅绿色沉淀洗净,真空烘干得到前驱体；步骤五：将前驱体在惰性气体中锻烧反应得到最终产物。本发明提供的合成方法具有工艺简单、耗能少、条件温和及产品形貌好等特点,适合大规模生产应用。(The invention relates to the technical field of catalysts, and discloses a Ni/C core-shell structure nano-material electrocatalyst and a preparation method thereof, aiming at the problem of low catalytic efficiency of hydrogen evolution of the existing electrocatalyst, wherein the preparation method comprises the following steps: the method comprises the following steps: dissolving nickel chloride hexahydrate in distilled water to form a first solution; step two: adding aminoacetic acid and isopropanol into the first solution to form a second solution; step three: stirring the second solution into a suspension, transferring the suspension into a container, carrying out gradient heating reaction, and cooling to room temperature to obtain a light green precipitate; step four: cleaning the collected light green precipitate, and drying in vacuum to obtain a precursor; step five: and (3) calcining the precursor in inert gas to react to obtain a final product. The synthesis method provided by the invention has the characteristics of simple process, low energy consumption, mild conditions, good product appearance and the like, and is suitable for large-scale production and application.)

1. The Ni/C nano material electrocatalyst is characterized in that the electrocatalyst is of a core-shell structure prepared by compounding nickel chloride hexahydrate and aminoacetic acid.

2. A method for preparing the Ni/C nanomaterial electrocatalyst of claim 1, comprising the steps of:

the method comprises the following steps: dissolving nickel chloride hexahydrate in distilled water to form a first solution;

step two: adding aminoacetic acid and isopropanol into the first solution to form a second solution;

step three: stirring the second solution into a suspension, transferring the suspension into a container, carrying out gradient heating reaction, and cooling to room temperature to obtain a light green precipitate;

step four: cleaning the collected light green precipitate, and drying in vacuum to obtain a precursor;

step five: and (3) calcining the precursor in inert gas to react to obtain a final product.

3. The method for preparing an Ni/C nanomaterial electrocatalyst according to claim 1, wherein in step one, 0.7-0.9g nickel chloride hexahydrate per 10mL distilled water.

4. The method for preparing the Ni/C nanomaterial electrocatalyst according to claim 1, wherein in step two, 0.3-0.5g of glycine is added per 30mL of isopropanol solution; the volume ratio of the isopropanol solution to the distilled water of the first step is 2-2.2: 1.

5. the method for preparing the Ni/C nanomaterial electrocatalyst according to claim 1, wherein in step three, the stirring is magnetic stirring for 10-20 min.

6. The method for preparing the Ni/C nanomaterial electrocatalyst of claim 1, wherein in step three, the gradient heating comprises: the first heating stage, the reaction temperature is 100-160 ℃, and the reaction time is 2-2.5 hours; the second heating stage is 180 ℃ and 200 ℃, and the reaction time is 3-4 hours.

7. The method for preparing an Ni/C nanomaterial electrocatalyst according to claim 1, wherein in the step four, the washing step is alternately washing with ionized water and anhydrous ethanol for 3-5 times, and simultaneously performing centrifugal separation, wherein the centrifugal rotation speed is 6000-.

8. The method for preparing an Ni/C nanomaterial electrocatalyst according to claim 1, characterized in that in step four, the temperature of vacuum drying is 70-75 ℃.

9. The method for preparing the Ni/C nano-material electrocatalyst according to claim 1, wherein in step five, the calcination reaction comprises: the first stage, the calcination temperature is 350-400 ℃, the calcination time is 0.6-1h, the second stage, the calcination temperature is 480-520 ℃, and the calcination time is 0.8-1.2 h; in the third stage, the calcination temperature is 300-350 ℃, and the calcination time is 0.5-0.6 h.

10. The method of claim 1, wherein in step five, the inert gas is argon.

Technical Field

The invention relates to the technical field of catalysts, in particular to a Ni/C core-shell structure nano-material electrocatalyst and a preparation method thereof.

Background

Hydrogen has been extensively studied as a clean renewable energy source as an increasingly diminishing alternative to fossil fuels. An efficient method for producing high purity hydrogen is the electrochemical decomposition of water into hydrogen and oxygen in an electrolytic cell. Water electrolysis is a sustainable, environmentally friendly method of hydrogen fuel production. The proton-rich environment is favorable for the adsorption of hydrogen on the surface of the catalyst, and the acidic medium is favorable for the hydrogen evolution reaction. However, acidic conditions prohibit the use of non-platinum group metals as catalysts. In addition, the corrosive acid mist generated by the acidic electrolyte not only pollutes the generated hydrogen gas, but also causes severe chemical corrosion to the electrolytic cell. These factors add significant hydrogen production costs and constitute an obstacle to the construction of large electrolytic cells. In addition, low vapor pressure and relatively mild chemical environment alkaline electrolytes can avoid these problems. More importantly, non-platinum group metals such as nickel can be used as an electrocatalyst/electrode for alkaline water electrolysis. In order to produce hydrogen efficiently, a suitable catalyst is needed to reduce the overpotential of the system, thereby minimizing the activation energy. Currently, noble metals such as platinum-based catalysts and their derivatives are the most active HER catalysts because they have optimal hydrogen binding (Δ GH ×) and the activation energy for hydrogen desorption from the platinum surface is low. Platinum catalyzed HER requires zero initial overpotential and results in high cathodic current density in acidic solutions. However, these catalysts have limited large-scale application due to their high cost.

Therefore, the key to realize the industrialization of the electrocatalyst is to search for a cheap and abundant non-noble metal high-efficiency electrocatalyst. According to the "volcanic effect" curve, transition metals such as Ni or Co have higher current densities and lower overpotentials due to their unoccupied d-orbitals and unpaired d-electrons. These transition metals and their derivatives have become an attractive catalyst as promising electrocatalysts. In particular, nickel-based materials are receiving increasing attention due to their wide source, low cost, expected durability in the working environment, and the like. However, their electrocatalytic activity, such as overpotential, stability, etc., still needs to be further improved to achieve the performance of noble metal electrocatalysts. In general, there are two strategies for improving the electrochemical performance of nickel-based materials. One is to improve the inherent electrochemical activity of the nickel-based material by introducing other catalytic components such as metal alloy, metal oxide or hydroxide, metal phosphide and sulfur-based compound; the composite catalytic component generally facilitates the adsorption of hydrogen atoms or the dissociation of water, thereby improving the electrocatalytic activity of the composite catalyst. The existing electrocatalyst is low in catalytic activity, and particularly poor in promotion effect on the improvement of hydrogen yield.

The invention discloses a nickel-based-carbon composite electrocatalyst and a preparation method thereof, and discloses the nickel-based-carbon composite electrocatalyst, wherein a porous carbonaceous conductive network formed by carbon fibers is used as a framework of the composite electrocatalyst, active nanoparticles with a core-shell structure are loaded on the framework, the core-shell structure comprises a core and two shells coated on the surface of the core, the active nanoparticles take a nickel simple substance as the core, nickel phosphide coated on the surface of the nickel simple substance is used as a first shell, and carbon coated on the surface of the nickel phosphide is used as a second shell. The invention also correspondingly provides a preparation method of the nickel-based-carbon composite electrocatalyst.

The method has the disadvantages that the catalyst promotes the oxygen evolution effect and does not contribute to the improvement of the hydrogen yield.

Disclosure of Invention

The invention aims to overcome the problem of low catalytic efficiency of hydrogen evolution by the existing electrocatalyst, and provides a Ni/C core-shell structure nano material electrocatalyst and a preparation method thereof. The synthesis method provided by the invention has the characteristics of simple process, low energy consumption, mild conditions, good product appearance and the like, and is suitable for large-scale production and application.

In order to achieve the purpose, the invention adopts the following technical scheme:

the electrocatalyst is a core-shell structure prepared by compounding nickel chloride hexahydrate and aminoacetic acid.

The composite material shows remarkable electrochemical activity in an acid solution due to the synergistic effect of the Ni core and the C shell layer. The metal Ni can be used as conductor to reduce internal resistance, and can convert H atoms into H₂(ii) a The specific surface area of the nickel-based catalyst is increased by reducing the size of the catalyst nanoparticles, and the prepared porous composite material has higher specific surface area and good electrochemical activity. The nickel metal particles are easy to be oxidized when being contacted with air, and the method of coating the nickel metal particles by carbon can isolate the contact of the inner core metal particles and the air, so that the nickel metal particles are protected, and the stability of the nickel metal particles is improved; at the same time, the carbon layer as the outer shell can act as a barrier layer to prevent the metal particles from agglomerating together by interaction. Even, the metal nano particles can have the unique property of the outer shell through surface coating, so that the electrocatalyst with the structure has stronger hydrogen evolution catalytic activity. The core/shell structure nano particles can also form one-dimensional porous nickel/carbon nano rods with high structure, small desorption pore size and large specific surface area, and the number of suspended chemical bonds is increased, so that the nano particles generate higher electrocatalytic activity in an electrochemical workstation, and the yield of hydrogen evolution is increased.

The preparation method of the Ni/C nano material electrocatalyst comprises the following steps:

the method comprises the following steps: dissolving nickel chloride hexahydrate in distilled water to form a first solution;

step two: adding aminoacetic acid and isopropanol into the first solution to form a second solution;

step three: stirring the second solution into a suspension, transferring the suspension into a container, carrying out gradient heating reaction, and cooling to room temperature to obtain a light green precipitate;

step four: cleaning the collected light green precipitate, and drying in vacuum to obtain a precursor;

step five: and (3) calcining the precursor in inert gas to react to obtain a final product.

Preferably, in step one, 0.7 to 0.9g of nickel chloride hexahydrate is used per 10mL of distilled water.

Preferably, in the second step, 0.3-0.5g of glycine is added to each 30mL of isopropanol solution; the volume ratio of the isopropanol solution to the distilled water of the first step is 2-2.2: 1.

preferably, in the third step, the stirring is magnetic stirring, and the stirring time is 10-20 min.

The magnetic stirring is adopted to ensure that reactants can be fully contacted, the reaction speed is accelerated, and the reaction device is lighter and easier to control compared with mechanical stirring.

Preferably, in step three, the gradient heating comprises: the first heating stage, the reaction temperature is 100-160 ℃, and the reaction time is 2-2.5 hours; the second heating stage is 180 ℃ and 200 ℃, and the reaction time is 3-4 hours.

And in the fourth step, the cleaning step is washing alternately for 3-5 times by using ionized water and absolute ethyl alcohol, and simultaneously carrying out centrifugal separation, wherein the centrifugal rotating speed is 6000-.

Preferably, in the fourth step, the temperature for vacuum drying is 70-75 ℃.

The vacuum drying oven is used for vacuumizing to remove gas components in the sample. And the common drying box can only simply dry the solvent in the sample. Too low a vacuum temperature may result in the sample not being crystallizable to achieve the desired drying conditions; too high a temperature may cause the sample to volatilize and deteriorate or to cake.

Preferably, in step five, the calcination reaction comprises: the first stage, the calcination temperature is 350-400 ℃, the calcination time is 0.6-1h, the second stage, the calcination temperature is 480-520 ℃, and the calcination time is 0.8-1.2 h; in the third stage, the calcination temperature is 300-350 ℃, and the calcination time is 0.5-0.6 h.

The precursor is calcined in a segmented manner, in the first stage, the shell layer can be gradually carbonized from inside to outside by lower-temperature calcination, the carbonization of the whole shell layer structure is more uniform, and the phenomenon that partial structure is incompletely carbonized due to one-time high-temperature carbonization is avoided for the prefabricated part of the porous shell layer structure; the second stage is to further strengthen the carbonization effect of the first stage, so that the shell structure is fully carbonized to form a stable porous shell structure, and the performance of the composite core/shell structure is improved; the third stage is the supplement of the previous stage, the carbonization effect of the previous stage is continued, and a buffer effect is played on the porous shell structure, so that the pores and the framework layout in the porous shell structure are adjusted and adapted in time at the next high temperature, the overall structure is more stable, the collapse of the pores in the porous shell structure caused by the instant reduction of the temperature to the room temperature after calcination is avoided, the prepared core/shell catalyst has more stable structure, more binding sites and higher catalytic activity.

If the calcination is insufficient, it may be mainly present as a precursor, that is, a block, and not as porous nanorods as we want, and if the calcination time at a high temperature is too long, the nanorods may be broken or internally collapsed, and then the specific surface area becomes small, and then the overall performance is deteriorated.

Preferably, in step five, the inert gas is argon.

In order to avoid doping impurity elements in the catalyst, argon with the most stable chemical property and low cost is used as protective gas, so that the obtained catalyst has higher purity and stronger catalytic activity.

Therefore, the invention has the following beneficial effects:

(1) the Ni/C core-shell structure nano material electrocatalyst prepared by the invention has the advantages that the one-dimensional porous nickel/carbon nano rod formed by the core/shell structure nano particles has high structure, smaller desorption aperture and larger specific surface area, and the number of suspended chemical bonds is increased, so that the electrocatalyst generates higher electrocatalytic activity in an electrochemical workstation, and has wide application prospect in the field of electrocatalysis;

(2) the Ni/C core-shell structure nano material electrocatalyst is prepared by respectively adopting gradient heating and sectional calcination, and the prepared electrocatalyst has the advantages of stable structure, more binding sites and high catalytic activity;

(3) the synthesis method provided by the invention has the characteristics of simple process, low energy consumption, mild conditions, good product appearance and the like, and is suitable for large-scale production and application.

Drawings

Fig. 1 is an XRD picture of example 1 of the present invention.

FIG. 2 is a SEM photograph of example 1 of the present invention.

FIG. 3 is a SEM photograph of example 2 of the present invention.

Fig. 4 is an SEM picture of comparative example 1 of the present invention.

Fig. 5 is an SEM picture of comparative example 2 of the present invention.

Fig. 6 is an SEM picture of comparative example 3 of the present invention.

Fig. 7 is an SEM picture of comparative example 4 of the present invention.

Fig. 8 is an SEM picture of comparative example 5 of the present invention.

Detailed Description

The invention is further described with reference to specific embodiments.

General examples

The electrocatalyst is a core-shell structure prepared by compounding nickel chloride hexahydrate and aminoacetic acid.

The preparation method of the Ni/C nano material electrocatalyst comprises the following steps:

the method comprises the following steps: dissolving nickel chloride hexahydrate in distilled water to form a first solution; 0.7-0.9g of nickel chloride hexahydrate per 10mL of distilled water.

Step two: adding aminoacetic acid and isopropanol into the first solution to form a second solution; 0.3-0.5g of glycine per 30mL of isopropanol solution; the volume ratio of the isopropanol solution to the distilled water of the first step is 2-2.2: 1.

step three: magnetically stirring the second solution for 10-20min to obtain a suspension, transferring the suspension into a container, performing gradient heating reaction, and cooling to room temperature to obtain a light green precipitate; the gradient heating comprises: the first heating stage, the reaction temperature is 100-160 ℃, and the reaction time is 2-2.5 hours; the second heating stage is 180 ℃ and 200 ℃, and the reaction time is 3-4 hours.

Step four: washing the collected light green precipitate with ionized water and anhydrous ethanol for 3-5 times alternately, and centrifuging at 6000-; vacuum drying at 70-75 deg.C to obtain precursor;

step five: calcining the precursor in argon to obtain a final product; the calcination reaction comprises the following steps: the first stage, the calcination temperature is 350-400 ℃, the calcination time is 0.6-1h, the second stage, the calcination temperature is 480-520 ℃, and the calcination time is 0.8-1.2 h; in the third stage, the calcination temperature is 300-350 ℃, and the calcination time is 0.5-0.6 h.

Example 1

The electrocatalyst is a core-shell structure prepared by compounding nickel chloride hexahydrate and aminoacetic acid.

The preparation method of the Ni/C nano material electrocatalyst comprises the following steps:

the method comprises the following steps: dissolving nickel chloride hexahydrate in distilled water to form a first solution; 0.8g of nickel chloride hexahydrate per 10mL of distilled water.

Step two: adding aminoacetic acid and isopropanol into the first solution to form a second solution; 0.4g of glycine per 30mL of isopropanol solution; the volume ratio of the isopropanol solution to the distilled water of step one is 2.1: 1.

step three: magnetically stirring the second solution for 15min to obtain a suspension, transferring the suspension into a container, performing gradient heating reaction, and cooling to room temperature to obtain a light green precipitate; the gradient heating comprises: the first heating stage, the temperature of reaction is 130 ℃, and the reaction time is 2.3 hours; the second heating stage was 190 ℃ and the reaction time was 3.5 hours.

Step four: washing the collected light green precipitate with ionized water and anhydrous ethanol for 4 times alternately, and centrifuging at 7000 r/min; drying at 73 ℃ in vacuum to obtain a precursor;

step five: calcining the precursor in argon to obtain a final product; the calcination reaction comprises the following steps: the first stage, the calcining temperature is 375 ℃, the calcining time is 0.8h, the second stage, the calcining temperature is 500 ℃, and the calcining time is 1 h; in the third stage, the calcining temperature is 325 ℃ and the calcining time is 0.55 h.

Example 2

The electrocatalyst is a core-shell structure prepared by compounding nickel chloride hexahydrate and aminoacetic acid.

The preparation method of the Ni/C nano material electrocatalyst comprises the following steps:

the method comprises the following steps: dissolving nickel chloride hexahydrate in distilled water to form a first solution; 0.7g of nickel chloride hexahydrate per 10mL of distilled water.

Step two: adding aminoacetic acid and isopropanol into the first solution to form a second solution; 0.3g of glycine per 30mL of isopropanol solution; the volume ratio of the isopropanol solution to the distilled water of the first step is 2: 1.

step three: magnetically stirring the second solution for 10min to obtain a suspension, transferring the suspension into a container, performing gradient heating reaction, and cooling to room temperature to obtain a light green precipitate; the gradient heating comprises: a first heating stage, wherein the reaction temperature is 100 ℃, and the reaction time is 2 hours; the second heating stage was 180 ℃ and the reaction time was 4 hours.

Step four: alternately washing the collected light green precipitate with ionized water and anhydrous ethanol for 3-5 times, and centrifuging at 6000 r/min; vacuum drying at 75 ℃ to obtain a precursor;

step five: calcining the precursor in argon to obtain a final product; the calcination reaction comprises the following steps: in the first stage, the calcining temperature is 350 ℃, the calcining time is 1h, and in the second stage, the calcining temperature is 480 ℃, and the calcining time is 1.2 h; in the third stage, the calcining temperature is 350 ℃, and the calcining time is 0.5 h.

Example 3

The electrocatalyst is a core-shell structure prepared by compounding nickel chloride hexahydrate and aminoacetic acid.

The preparation method of the Ni/C nano material electrocatalyst comprises the following steps:

the method comprises the following steps: dissolving nickel chloride hexahydrate in distilled water to form a first solution; 0.9g of nickel chloride hexahydrate per 10mL of distilled water.

Step two: adding aminoacetic acid and isopropanol into the first solution to form a second solution; 0.5g of glycine per 30mL of isopropanol solution; the volume ratio of the isopropanol solution to the distilled water of step one is 2.2: 1.

step three: magnetically stirring the second solution for 20min to obtain a suspension, transferring the suspension into a container, performing gradient heating reaction, and cooling to room temperature to obtain a light green precipitate; the gradient heating comprises: a first heating stage, wherein the reaction temperature is 160 ℃, and the reaction time is 2 hours; the second heating stage was 200 ℃ with a reaction time of 3 hours.

Step four: alternately washing the collected light green precipitate with ionized water and anhydrous ethanol for 5 times, and centrifuging at 8000 r/min; vacuum drying at 75 ℃ to obtain a precursor;

step five: calcining the precursor in argon to obtain a final product; the calcination reaction comprises the following steps: the first stage, the calcining temperature is 400 ℃, the calcining time is 0.6h, the second stage, the calcining temperature is 520 ℃, and the calcining time is 0.8 h; in the third stage, the calcining temperature is 350 ℃, and the calcining time is 0.6 h.

Example 4

The electrocatalyst is a core-shell structure prepared by compounding nickel chloride hexahydrate and aminoacetic acid.

The preparation method of the Ni/C nano material electrocatalyst comprises the following steps:

the method comprises the following steps: dissolving nickel chloride hexahydrate in distilled water to form a first solution; 0.75g of nickel chloride hexahydrate per 10mL of distilled water.

Step two: adding aminoacetic acid and isopropanol into the first solution to form a second solution; 0.35g of glycine per 30mL of isopropanol solution; the volume ratio of the isopropanol solution to the distilled water of step one is 2.05: 1.

step three: magnetically stirring the second solution for 12min to obtain a suspension, transferring the suspension into a container, performing gradient heating reaction, and cooling to room temperature to obtain a light green precipitate; the gradient heating comprises: the first heating stage, the reaction temperature is 110 ℃, and the reaction time is 2.1 hours; the second heating stage was 185 ℃ with a reaction time of 3.2 hours.

Step four: alternately washing the collected light green precipitate with ionized water and anhydrous ethanol for 3 times, and centrifuging at 6500 r/min; drying at 71 ℃ in vacuum to obtain a precursor;

step five: calcining the precursor in argon to obtain a final product; the calcination reaction comprises the following steps: the first stage, the calcining temperature is 360 ℃, the calcining time is 0.71h, the second stage, the calcining temperature is 490 ℃, the calcining time is 0.9 h; in the third stage, the calcining temperature is 310 ℃ and the calcining time is 0.52 h.

Example 5

The electrocatalyst is a core-shell structure prepared by compounding nickel chloride hexahydrate and aminoacetic acid.

The preparation method of the Ni/C nano material electrocatalyst comprises the following steps:

the method comprises the following steps: dissolving nickel chloride hexahydrate in distilled water to form a first solution; 0.85g of nickel chloride hexahydrate per 10mL of distilled water.

Step two: adding aminoacetic acid and isopropanol into the first solution to form a second solution; 0.45g of glycine per 30mL of isopropanol solution; the volume ratio of the isopropanol solution to the distilled water of step one is 2.15: 1.

step three: magnetically stirring the second solution for 18min to obtain a suspension, transferring the suspension into a container, performing gradient heating reaction, and cooling to room temperature to obtain a light green precipitate; the gradient heating comprises: in the first heating stage, the reaction temperature is 150 ℃, and the reaction time is 2.4 hours; the second heating stage was 195 ℃ and the reaction time was 3.8 hours.

Step four: washing the collected light green precipitate with ionized water and anhydrous ethanol for 4 times alternately, and centrifuging at 7500 r/min; drying at 74 ℃ in vacuum to obtain a precursor;

step five: calcining the precursor in argon to obtain a final product; the calcination reaction comprises the following steps: the first stage, the calcination temperature is 390 ℃, the calcination time is 0.9h, the second stage, the calcination temperature is 510 ℃, the calcination time is 1.1 h; in the third stage, the calcining temperature is 340 ℃ and the calcining time is 0.58 h.

Comparative example 1 (different from example 1 in that the calcination temperature in the second stage was 400 deg.C.)

The electrocatalyst is a core-shell structure prepared by compounding nickel chloride hexahydrate and aminoacetic acid.

The preparation method of the Ni/C nano material electrocatalyst comprises the following steps:

the method comprises the following steps: dissolving nickel chloride hexahydrate in distilled water to form a first solution; 0.8g of nickel chloride hexahydrate per 10mL of distilled water.

Step two: adding aminoacetic acid and isopropanol into the first solution to form a second solution; 0.4g of glycine per 30mL of isopropanol solution; the volume ratio of the isopropanol solution to the distilled water of step one is 2.1: 1.

step three: magnetically stirring the second solution for 15min to obtain a suspension, transferring the suspension into a container, performing gradient heating reaction, and cooling to room temperature to obtain a light green precipitate; the gradient heating comprises: the first heating stage, the temperature of reaction is 130 ℃, and the reaction time is 2.3 hours; the second heating stage was 190 ℃ and the reaction time was 3.5 hours.

Step four: washing the collected light green precipitate with ionized water and anhydrous ethanol for 4 times alternately, and centrifuging at 7000 r/min; drying at 73 ℃ in vacuum to obtain a precursor;

step five: calcining the precursor in argon to obtain a final product; the calcination reaction comprises the following steps: the first stage, the calcining temperature is 375 ℃, the calcining time is 0.8h, the second stage, the calcining temperature is 400 ℃, and the calcining time is 1 h; in the third stage, the calcining temperature is 325 ℃ and the calcining time is 0.55 h.

Comparative example 2 (different from example 1 in that the calcination temperature in the second stage was 550 ℃.)

The electrocatalyst is a core-shell structure prepared by compounding nickel chloride hexahydrate and aminoacetic acid.

The preparation method of the Ni/C nano material electrocatalyst comprises the following steps:

the method comprises the following steps: dissolving nickel chloride hexahydrate in distilled water to form a first solution; 0.8g of nickel chloride hexahydrate per 10mL of distilled water.

Step two: adding aminoacetic acid and isopropanol into the first solution to form a second solution; 0.4g of glycine per 30mL of isopropanol solution; the volume ratio of the isopropanol solution to the distilled water of step one is 2.1: 1.

step three: magnetically stirring the second solution for 15min to obtain a suspension, transferring the suspension into a container, performing gradient heating reaction, and cooling to room temperature to obtain a light green precipitate; the gradient heating comprises: the first heating stage, the temperature of reaction is 130 ℃, and the reaction time is 2.3 hours; the second heating stage was 190 ℃ and the reaction time was 3.5 hours.

Step four: washing the collected light green precipitate with ionized water and anhydrous ethanol for 4 times alternately, and centrifuging at 7000 r/min; drying at 73 ℃ in vacuum to obtain a precursor;

step five: calcining the precursor in argon to obtain a final product; the calcination reaction comprises the following steps: the first stage, the calcining temperature is 375 ℃, the calcining time is 0.8h, the second stage, the calcining temperature is 550 ℃, and the calcining time is 1 h; in the third stage, the calcining temperature is 325 ℃ and the calcining time is 0.55 h.

Comparative example 3 (differing from example 1 in that no first stage of the calcination reaction was provided.)

The electrocatalyst is a core-shell structure prepared by compounding nickel chloride hexahydrate and aminoacetic acid.

The preparation method of the Ni/C nano material electrocatalyst comprises the following steps:

the method comprises the following steps: dissolving nickel chloride hexahydrate in distilled water to form a first solution; 0.8g of nickel chloride hexahydrate per 10mL of distilled water.

Step two: adding aminoacetic acid and isopropanol into the first solution to form a second solution; 0.4g of glycine per 30mL of isopropanol solution; the volume ratio of the isopropanol solution to the distilled water of step one is 2.1: 1.

step three: magnetically stirring the second solution for 15min to obtain a suspension, transferring the suspension into a container, performing gradient heating reaction, and cooling to room temperature to obtain a light green precipitate; the gradient heating comprises: the first heating stage, the temperature of reaction is 130 ℃, and the reaction time is 2.3 hours; the second heating stage was 190 ℃ and the reaction time was 3.5 hours.

Step four: washing the collected light green precipitate with ionized water and anhydrous ethanol for 4 times alternately, and centrifuging at 7000 r/min; drying at 73 ℃ in vacuum to obtain a precursor;

step five: calcining the precursor in argon to obtain a final product; the calcination reaction comprises the following steps: in the second stage, the calcining temperature is 500 ℃, and the calcining time is 1 h; in the third stage, the calcining temperature is 325 ℃ and the calcining time is 0.55 h.

Comparative example 4 (different from example 1 in that the volume ratio of the isopropyl alcohol solution to the distilled water was 5: 1.)

The electrocatalyst is a core-shell structure prepared by compounding nickel chloride hexahydrate and aminoacetic acid.

The preparation method of the Ni/C nano material electrocatalyst comprises the following steps:

the method comprises the following steps: dissolving nickel chloride hexahydrate in distilled water to form a first solution; 0.8g of nickel chloride hexahydrate per 10mL of distilled water.

Step two: adding aminoacetic acid and isopropanol into the first solution to form a second solution; 0.4g of glycine per 30mL of isopropanol solution; the volume ratio of the isopropanol solution to the distilled water of the first step is 5: 1.

step three: magnetically stirring the second solution for 15min to obtain a suspension, transferring the suspension into a container, performing gradient heating reaction, and cooling to room temperature to obtain a light green precipitate; the gradient heating comprises: the first heating stage, the temperature of reaction is 130 ℃, and the reaction time is 2.3 hours; the second heating stage was 190 ℃ and the reaction time was 3.5 hours.

Step four: washing the collected light green precipitate with ionized water and anhydrous ethanol for 4 times alternately, and centrifuging at 7000 r/min; drying at 73 ℃ in vacuum to obtain a precursor;

step five: calcining the precursor in argon to obtain a final product; the calcination reaction comprises the following steps: the first stage, the calcining temperature is 375 ℃, the calcining time is 0.8h, the second stage, the calcining temperature is 500 ℃, and the calcining time is 1 h; in the third stage, the calcining temperature is 325 ℃ and the calcining time is 0.55 h.

Comparative example 5 (differing from example 1 in that the reaction time of the second heating stage was 1.5 h.)

The electrocatalyst is a core-shell structure prepared by compounding nickel chloride hexahydrate and aminoacetic acid.

The preparation method of the Ni/C nano material electrocatalyst comprises the following steps:

the method comprises the following steps: dissolving nickel chloride hexahydrate in distilled water to form a first solution; 0.8g of nickel chloride hexahydrate per 10mL of distilled water.

Step two: adding aminoacetic acid and isopropanol into the first solution to form a second solution; 0.4g of glycine per 30mL of isopropanol solution; the volume ratio of the isopropanol solution to the distilled water of step one is 2.1: 1.

step three: magnetically stirring the second solution for 15min to obtain a suspension, transferring the suspension into a container, performing gradient heating reaction, and cooling to room temperature to obtain a light green precipitate; the gradient heating comprises: the first heating stage, the temperature of reaction is 130 ℃, and the reaction time is 2.3 hours; the second heating stage was 190 ℃ and the reaction time was 1.5 hours.

Step four: washing the collected light green precipitate with ionized water and anhydrous ethanol for 4 times alternately, and centrifuging at 7000 r/min; drying at 73 ℃ in vacuum to obtain a precursor;

step five: calcining the precursor in argon to obtain a final product; the calcination reaction comprises the following steps: the first stage, the calcining temperature is 375 ℃, the calcining time is 0.8h, the second stage, the calcining temperature is 500 ℃, and the calcining time is 1 h; in the third stage, the calcining temperature is 325 ℃ and the calcining time is 0.55 h.

Table 1 shows the relevant performance of each item and Ni/C core-shell structure nano material electrocatalyst

And (4) conclusion: only the Ni/C nano-material electrocatalyst prepared in the embodiment 1 of the invention has better catalytic activator and stronger hydrogen evolution capability.

Comparative example 1 differs from example 1 in that the calcination temperature in the second stage is 400 ℃; the calcination temperature at this time is not sufficient to completely calcine the bulk precursor into porous nanorods.

Comparative example 2 differs from example 1 in that the calcination temperature in the second stage is 550 ℃; the calcination temperature at this time causes the resulting nanorods to break and form many small rod-like structures.

Comparative example 3 differs from example 1 in that there is no first stage of the calcination reaction; when the precursor is directly heated to the second stage, the precursor is directly heated to the required temperature from a low-temperature state, and the thickness of the calcined one-dimensional nanorods is not uniform.

Comparative example 4 differs from example 1 in that the volume ratio of isopropanol solution to distilled water is 5: 1; specific surface area at this time to isopropyl alcohol: water 2: 1, the time is smaller, the desorption aperture is larger, and the size of the generated one-dimensional nano rod is not uniform.

Comparative example 5 differs from example 1 in that the reaction time of the second heating stage was 1.5 h; when the second heating stage is too long, compared with the nanorod generated under the condition of lower reaction temperature, the blocky precursor is completely split, and the nanorod is continuously calcined on the basis of uniform splitting, so that the thickness of the dimensional nanorod structure is uneven. The electrocatalysts obtained in comparative examples 1-5 have poor structural stability and low structural integrity, so that the catalytic activity of the reaction is reduced.

FIG. 1: the prepared Ni/C nano material electrocatalyst has good crystallinity, does not generate other impurities and has higher purity.

FIGS. 2 to 3: the prepared Ni/C nano material electrocatalyst can contain more Ni/C nano rods, and the thickness and the size are relatively uniform. And it can be seen that the nanorods are composed of many nano-small particles and have a porous structure.

FIG. 4: the prepared Ni/C nano material electrocatalyst obtains a small amount of Ni/C nano rods, but most products exist in a massive precursor state and have nonuniform sizes.

FIG. 5: the prepared Ni/C nano material electrocatalyst is slightly broken to generate a slightly broken rod-shaped structure, and a one-dimensional nanorod structure with uniform thickness and poor structural integrity can be obtained.

FIG. 6: the prepared Ni/C nano material electrocatalyst is broken to generate a plurality of small rod-shaped structures, and the shape of the small rod-shaped structures is obviously not as uniform as that of nanorods generated at 500 ℃.

FIG. 7: the prepared Ni/C nano material electrocatalyst has very nonuniform calcined nano rods due to the difference of solvent ratio.

FIG. 8: the prepared Ni/C nano material electrocatalyst has good micro-morphology, and can obtain a nano rod structure with uneven thickness;

it can be seen from the data of examples 1-5 and comparative examples 1-5 that only the solution within the scope of the claims of the present invention can satisfy the above requirements in all aspects, and an optimized solution can be obtained, and an optimal Ni/C nanomaterial electrocatalyst can be obtained. The change of the mixture ratio, the replacement/addition/subtraction of raw materials or the change of the feeding sequence can bring corresponding negative effects.

The raw materials and equipment used in the invention are common raw materials and equipment in the field if not specified; the methods used in the present invention are conventional in the art unless otherwise specified.

The above description is only a preferred embodiment of the present invention, and is not intended to limit the present invention, and all simple modifications, alterations and equivalents of the above embodiments according to the technical spirit of the present invention are still within the protection scope of the technical solution of the present invention.