Cobalt-based catalyst and preparation method and application thereof

Abstract

The invention provides a cobalt-based catalyst and a preparation method and application thereof, the chemical formula of the cobalt-based catalyst is Co (OH) x (CO3) 1-0.5 x, x is not higher than 2, and the cobalt-based catalyst has a nanofiber three-dimensional network structure. The cobalt-based catalyst provided by the invention has a nanofiber three-dimensional network structure, and the agglomeration phenomenon is greatly improved, so that the cobalt-based catalyst has a relatively high specific surface area, more active sites can be exposed, and the cobalt-based catalyst has excellent catalytic performance.

Description

Technical Field

[0001] The present invention belongs to the technical field of catalysts and relates to a cobalt-based catalyst, in particular to a cobalt-based catalyst and a preparation method and application thereof. Background Art

[0002] Cobalt-based catalysts have important applications in energy conversion, environmental treatment, and chemical synthesis, particularly in catalytic oxidation and hydrogen production from water electrolysis. In recent years, with the growing demand for clean energy, researchers have devoted considerable attention to the regulation of catalyst active sites and the optimization of surface structures. Basic cobalt carbonate (Co(OH)2·CoCO3) has become a popular candidate for cobalt-based catalysts due to its layered structure and tunable electronic properties.

[0003] However, existing research shows that traditional basic cobalt carbonate catalysts still face difficult-to-solve problems; the particle agglomeration phenomenon of traditional basic cobalt carbonate catalysts in existing technologies is significant, and the specific surface area and active site density are relatively low.

[0004] CN113522326A discloses a method for preparing nickel-doped basic cobalt carbonate for catalysts, which includes the following steps: preparing a cobalt salt solution, a nickel salt solution, a precipitant solution, and a liquid alkali solution respectively, and setting them aside; adding the above-mentioned cobalt salt solution, nickel salt solution, and precipitant solution to a reactor at a specified volume ratio, and adjusting the pH value of the reaction system to 8.5-10.5 by using a liquid alkali solution, and controlling the feed flow rate of the cobalt salt during the reaction, and reacting to obtain a nickel-doped basic cobalt carbonate slurry; then subjecting the above-mentioned basic cobalt carbonate slurry to solid-liquid separation, slurry washing, and drying to obtain the target basic cobalt carbonate. After testing, it was found that the target nickel-doped basic cobalt carbonate obtained by the method of the patent document has a large particle size and a petal-shaped surface morphology; using basic cobalt carbonate with such a structure to prepare a catalyst can effectively improve the activity and service life of the catalyst.

[0005] CN106011926A discloses a cobalt-based multi-level nanocomposite structure electrocatalyst for electrolysis of water to produce oxygen and a preparation method thereof, comprising the following steps: dissolving cobalt nitrate hexahydrate, urea, and ammonium fluoride in deionized water to obtain a precursor solution, transferring the solution to a hydrothermal reactor, adding carbon fiber paper, and growing basic cobalt carbonate nanowires on the carbon fiber paper by a solvent thermal reaction; after the reaction is completed, naturally cooling, removing the product, rinsing, and drying to obtain a carbon fiber paper-supported basic cobalt carbonate nanowire composite structure; then, using sulfur powder as a raw material, a carbon fiber paper-supported cobalt sulfide nanowire composite structure is prepared by a low-temperature sulfurization reaction under an inert gas; finally, a layer of cobalt hydroxide nanosheets is electroplated on the surface of the carbon fiber paper-supported cobalt sulfide nanowire composite structure by electrochemical deposition to obtain a cobalt-based multi-level nanocomposite structure electrocatalyst for electrolysis of water to produce oxygen. However, the catalytic activity of the cobalt-based multi-level nanocomposite structure electrocatalyst for electrolysis of water to produce oxygen still cannot meet the requirements of practical applications.

[0006] Cobalt-based catalysts disclosed in the prior art all have certain drawbacks, including significant particle agglomeration and low specific surface area, which leads to insufficient catalytic activity. Therefore, the development and design of a new cobalt-based catalyst, its preparation method, and its application are of vital importance. Summary of the Invention

[0007] In view of the shortcomings of the existing technology, the purpose of the present invention is to provide a cobalt-based catalyst and its preparation method and application. The cobalt-based catalyst provided by the present invention has a three-dimensional network structure of nanofibers, and the agglomeration phenomenon is greatly improved. Therefore, it has a higher specific surface area and can expose more active sites. Therefore, it has excellent catalytic performance.

[0008] To achieve this object, the present invention adopts the following technical solutions:

[0009] In a first aspect, the present invention provides a cobalt-based catalyst having the chemical formula Co(OH) x (CO3) 1-0.5x , x is not higher than 2, and the cobalt-based catalyst has a nanofiber three-dimensional network structure.

[0010] In the present invention, the chemical formula of the cobalt-based catalyst is Co(OH) x (CO3) 1-0.5x , x is not higher than 2, for example, it can be 0, 0.2, 0.4, 0.6, 0.8, 1.0, 1.2, 1.4, 1.6, 1.8 or 2.0, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0011] The cobalt-based catalyst provided by the present invention has a three-dimensional nanofiber network structure, and the agglomeration phenomenon is greatly improved, so it has a higher specific surface area and can expose more active sites, thereby having excellent catalytic performance.

[0012] Preferably, the specific surface area of ​​the cobalt-based catalyst is 235 to 255 m 2 / g, for example, it can be 235m 2 / g, 237m 2 / g、239m 2 / g, 241m 2 / g, 243m 2 / g, 245m 2 / g, 247m 2 / g、249m 2 / g, 251m 2 / g、253m 2 / g or 255m 2 / g, but is not limited to the listed values, and other values ​​not listed within the numerical range are also applicable.

[0013] Preferably, the average particle size of the cobalt-based catalyst is 15.0 to 23.5 nm, for example, 15.0 nm, 15.5 nm, 16.0 nm, 16.5 nm, 17.0 nm, 17.5 nm, 18.0 nm, 18.5 nm, 19.0 nm, 19.5 nm, 20.0 nm, 20.5 nm, 21.0 nm, 21.5 nm, 22.0 nm, 22.5 nm, 23.0 nm or 23.5 nm, but is not limited to the listed values, and other unlisted values ​​within this numerical range are also applicable.

[0014] Preferably, the half-peak width of the (020) crystal plane of the cobalt-based catalyst is 0.547 to 0.691, for example, it can be 0.547, 0.555, 0.563, 0.571, 0.579, 0.587, 0.595, 0.603, 0.611, 0.619, 0.627, 0.635, 0.643, 0.651, 0.659, 0.667, 0.675, 0.683 or 0.691, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0015] Preferably, based on the mass of the cobalt-based catalyst as a percentage, the mass fraction of cobalt in the cobalt-based catalyst is 48.1-51.2wt%, for example, it can be 48.1wt%, 48.3wt%, 48.5wt%, 48.7wt%, 48.9wt%, 49.1wt%, 49.3wt%, 49.5wt%, 49.7wt%, 49.9wt%, 50.1wt%, 50.3wt%, 50.5wt%, 50.7wt%, 50.9wt%, 51.1wt% or 51.2wt%, but is not limited to the listed values, and other unlisted values ​​within this numerical range are equally applicable.

[0016] In a second aspect, the present invention provides a method for preparing the cobalt-based catalyst according to the first aspect, the preparation method comprising:

[0017] The cobalt salt solution and the precipitant solution are continuously added to the reaction base solution to carry out a coprecipitation reaction for 10 to 15 hours to obtain a cobalt-based catalyst;

[0018] The cobalt salt solution is added to the reaction base solution in a manner including air injection.

[0019] In the preparation method provided by the present invention, a cobalt-based catalyst with a high specific surface area and a nanofiber three-dimensional network structure can be prepared through only simple steps, and the preparation process is simple and the preparation cost is low.

[0020] In the present invention, the coprecipitation reaction is carried out for 10 to 15 hours, for example, it can be 10 hours, 10.5 hours, 11 hours, 11.5 hours, 12 hours, 12.5 hours, 13 hours, 13.5 hours, 14 hours, 14.5 hours or 15 hours, but it is not limited to the listed values. Other values ​​not listed within the numerical range are also applicable.

[0021] Preferably, the flow rate of the cobalt salt solution added to the reaction base liquid is 1.6 to 1.8 kg / h, for example, it can be 1.60 kg / h, 1.62 kg / h, 1.64 kg / h, 1.66 kg / h, 1.68 kg / h, 1.70 kg / h, 1.72 kg / h, 1.74 kg / h, 1.76 kg / h, 1.78 kg / h or 1.80 kg / h, but is not limited to the listed values, and other values ​​not listed within this numerical range are also applicable.

[0022] Preferably, the cobalt ion concentration in the cobalt salt solution is 110-130 g / L, for example, it can be 110 g / L, 112 g / L, 114 g / L, 116 g / L, 118 g / L, 120 g / L, 122 g / L, 124 g / L, 126 g / L, 128 g / L or 130 g / L, but is not limited to the listed values, and other unlisted values ​​within this numerical range are also applicable.

[0023] Preferably, the air flow rate in the air injection is 3 to 5 m 3 / h, for example, it can be 3.0m3 / h, 3.2m 3 / h、3.4m 3 / h、3.6m 3 / h、3.8m 3 / h、4.0m 3 / h、4.2m 3 / h、4.4m 3 / h、4.6m 3 / h, 4.8m3 / h or 5.0m3 / h, but is not limited to the listed values. Other values ​​not listed within the numerical range are also applicable.

[0024] Preferably, the flow rate of the precipitant solution added to the reaction base liquid is 2.9-3~1kg / h, for example, it can be 2.90kg / h, 2.92kg / h, 2.94kg / h, 2.96kg / h, 2.98kg / h, 3.00kg / h, 3.02kg / h, 3.04kg / h, 3.06kg / h, 3.08kg / h or 3.10kg / h, but is not limited to the listed values, and other unlisted values ​​within this numerical range are also applicable.

[0025] Preferably, the concentration of the precipitant in the precipitant solution is 220-260 g / L, for example, it can be 220 g / L, 225 g / L, 230 g / L, 235 g / L, 240 g / L, 245 g / L, 250 g / L, 255 g / L or 260 g / L, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0026] Preferably, the precipitant in the precipitant solution comprises sodium carbonate and / or sodium bicarbonate.

[0027] Preferably, the pH of the reaction base solution is 8.3-8.6, for example, 8.30, 8.32, 8.34, 8.36, 8.38, 8.40, 8.42, 8.44, 8.46, 8.48, 8.50, 8.52, 8.54, 8.56, 8.58 or 8.60, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0028] Preferably, the reaction base liquid comprises an aqueous solution of ammonium bicarbonate.

[0029] Preferably, during the coprecipitation reaction, the pH is controlled to be 7.3-7.5, and the reaction is stirred at a rotation speed of 400-550 rpm.

[0030] In the present invention, in the coprecipitation reaction, the pH is controlled to be 7.3-7.5, for example, it can be 7.30, 7.32, 7.34, 7.36, 7.38, 7.40, 7.42, 7.44, 7.46, 7.48 or 7.50, but is not limited to the listed values, and other values ​​not listed within the numerical range are also applicable.

[0031] In the present invention, the coprecipitation reaction is accompanied by stirring at a rotation speed of 400 to 550 rpm, for example, 400 rpm, 420 rpm, 440 rpm, 460 rpm, 480 rpm, 500 rpm, 520 rpm, 540 rpm or 550 rpm, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0032] As a preferred technical solution of the preparation method of the present invention, the preparation method comprises:

[0033] A cobalt salt solution having a cobalt ion concentration of 110 to 130 g / L and a precipitant solution having a concentration of 220 to 260 g / L are continuously added to an aqueous ammonium bicarbonate solution having a pH of 8.3 to 8.6, and a coprecipitation reaction is carried out for 10 to 15 hours. During the coprecipitation reaction, the pH is controlled at 7.3 to 7.5 and the stirring speed is 400 to 550 rpm to obtain a cobalt-based catalyst.

[0034] The flow rate of the cobalt salt solution added to the reaction base liquid is 1.6-1.8 kg / h, and the cobalt salt solution is added to the reaction base liquid in a manner including air injection, and the air flow rate in the air injection is 3-5 m 3 / h.

[0035] In a third aspect, the present invention provides an application of a cobalt-based catalyst, wherein the cobalt-based catalyst is used for catalytic oxidation or electrolysis of water to produce hydrogen.

[0036] The numerical range described in the present invention includes not only the point values ​​listed above, but also any point values ​​between the above numerical ranges that are not listed. Due to space limitations and for the sake of simplicity, the present invention no longer exhaustively lists the specific point values ​​included in the range.

[0037] Compared with the prior art, the present invention has the following beneficial effects:

[0038] The cobalt-based catalyst provided by the present invention has a three-dimensional nanofiber network structure, and the agglomeration phenomenon is greatly improved, so it has a higher specific surface area and can expose more active sites, thereby having excellent catalytic performance. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] Figure 1 is a SEM image of the cobalt-based catalyst provided in Example 1 at a magnification of 20,000 times.

[0040] Figure 2 is a SEM image of the cobalt-based catalyst provided in Example 1 at a magnification of 30,000 times.

[0041] Figure 3 is the XRD pattern of the cobalt-based catalyst provided in Example 1.

[0042] Figure 4 This is a SEM image of the cobalt-based catalyst provided in Comparative Example 1 at a magnification of 20,000 times.

[0043] Figure 5 This is a SEM image of the cobalt-based catalyst provided in Comparative Example 1 at a magnification of 30,000 times.

[0044] Figure 6 This is a SEM image of the cobalt-based catalyst provided in Comparative Example 2 at a magnification of 20,000 times.

[0045] Figure 7 This is a SEM image of the cobalt-based catalyst provided in Comparative Example 2 at a magnification of 30,000 times.

[0046] Figure 8 This is a SEM image of the cobalt-based catalyst provided in Comparative Example 3 at a magnification of 10,000 times.

[0047] Figure 9 This is a SEM image of the cobalt-based catalyst provided in Comparative Example 3 at a magnification of 20,000 times. DETAILED DESCRIPTION

[0048] The technical solution of the present invention is further described below by way of specific embodiments. It should be understood by those skilled in the art that the embodiments are merely to help understand the present invention and should not be regarded as specific limitations of the present invention.

[0049] Example 1

[0050] This embodiment provides a cobalt-based catalyst, the chemical formula of which is Co(OH) 0.2 (CO3) 0.9 The cobalt-based catalyst has a nanofiber three-dimensional network structure, and the specific surface area of ​​the cobalt-based catalyst is 245m 2 / g, the average particle size is 19.2nm, and the half-peak width of the (020) crystal plane is 0.615;

[0051] Based on the mass of the cobalt-based catalyst as 100%, the mass fraction of cobalt in the cobalt-based catalyst is 50.7 wt %;

[0052] The preparation method of the cobalt-based catalyst comprises:

[0053] A cobalt chloride hexahydrate solution having a cobalt ion concentration of 120 g / L and an ammonium bicarbonate solution having a concentration of 240 g / L were continuously added to an ammonium bicarbonate aqueous solution having a pH of 8.4, and a coprecipitation reaction was carried out for 12 hours. During the coprecipitation reaction, the pH was controlled at 7.4 and the stirring speed was 470 rpm to obtain a cobalt-based catalyst;

[0054] The flow rate of the cobalt chloride hexahydrate solution added to the ammonium bicarbonate aqueous solution is 1.7 kg / h, and the method of adding the cobalt chloride hexahydrate solution to the ammonium bicarbonate aqueous solution includes air injection, and the air flow rate in the air injection is 4m 3 / h.

[0055] The cobalt-based catalyst provided in this embodiment was tested using a scanning electron microscope, and the SEM image of the cobalt-based catalyst provided in this embodiment at a magnification of 20,000 times was obtained. Figure 1 As shown; the SEM image at a magnification of 30,000 times is as shown Figure 2 shown.

[0056] The cobalt-based catalyst (basic cobalt carbonate) provided in this embodiment was tested using an X-ray diffractometer, and the XRD pattern of the cobalt-based catalyst was as follows: Figure 3 shown.

[0057] Example 2

[0058] This embodiment provides a cobalt-based catalyst, the chemical formula of which is Co(OH) 0.3 (CO3) 0.85 The cobalt-based catalyst has a nanofiber three-dimensional network structure, and the specific surface area of ​​the cobalt-based catalyst is 235m 2 / g, the average particle size is 23.5nm, and the half-peak width of the (020) crystal plane is 0.547;

[0059] Based on the mass of the cobalt-based catalyst as 100%, the mass fraction of cobalt in the cobalt-based catalyst is 51.2 wt%;

[0060] The preparation method of the cobalt-based catalyst comprises:

[0061] A cobalt chloride hexahydrate solution having a cobalt ion concentration of 130 g / L and an ammonium bicarbonate solution having a concentration of 220 g / L were continuously added to an ammonium bicarbonate aqueous solution having a pH of 8.3, and a coprecipitation reaction was carried out for 15 hours. During the coprecipitation reaction, the pH was controlled at 7.3 and the stirring speed was 550 rpm to obtain a cobalt-based catalyst;

[0062] The flow rate of the cobalt chloride hexahydrate solution added to the ammonium bicarbonate aqueous solution is 1.6 kg / h, and the method of adding the cobalt chloride hexahydrate solution to the ammonium bicarbonate aqueous solution includes air injection, and the air flow rate in the air injection is 5m 3 / h.

[0063] Example 3

[0064] This embodiment provides a cobalt-based catalyst, the chemical formula of which is Co(OH) 0.08 (CO3) 0.96 The cobalt-based catalyst has a nanofiber three-dimensional network structure, and the specific surface area of ​​the cobalt-based catalyst is 255m 2 / g, the average particle size is 15.0nm, and the half-peak width of the (020) crystal plane is 0.691;

[0065] Based on the mass of the cobalt-based catalyst as 100%, the mass fraction of cobalt in the cobalt-based catalyst is 50.0 wt %;

[0066] The preparation method of the cobalt-based catalyst comprises:

[0067] A cobalt chloride hexahydrate solution having a cobalt ion concentration of 110 g / L and an ammonium bicarbonate solution having a concentration of 260 g / L were continuously added to an ammonium bicarbonate aqueous solution having a pH of 8.6, and a coprecipitation reaction was carried out for 10 hours. During the coprecipitation reaction, the pH was controlled to 7.5 and the mixture was stirred at 400 rpm to obtain a cobalt-based catalyst.

[0068] The flow rate of the cobalt chloride hexahydrate solution added to the ammonium bicarbonate aqueous solution is 1.8 kg / h, and the method of adding the cobalt chloride hexahydrate solution to the ammonium bicarbonate aqueous solution includes air injection, and the air flow rate in the air injection is 3m 3 / h.

[0069] Example 4

[0070] This embodiment provides a cobalt-based catalyst, except that the specific surface area of ​​the cobalt-based catalyst is 210m 2 / g, the average particle size is 25.2nm, and the half-peak width of the (020) crystal plane is 0.537;

[0071] That is, in the preparation method of the cobalt-based catalyst, the air flow rate in the air injection is 2m 3 / h, the rest are the same as in Example 1.

[0072] Example 5

[0073] This embodiment provides a cobalt-based catalyst, except that the specific surface area of ​​the cobalt-based catalyst is 280m 2 / g, the average particle size is 14.3nm, and the half-peak width of the (020) crystal plane is 0.735;

[0074] That is, in the preparation method of the cobalt-based catalyst, the air flow rate in the air injection is 6m 3 / h, the rest are the same as in Example 1.

[0075] Example 6

[0076] This embodiment provides a cobalt-based catalyst, except that the chemical formula of the cobalt-based catalyst is Co(OH) 0.4 (CO3) 0.8 , based on the mass of the cobalt-based catalyst as 100%, the mass fraction of cobalt in the cobalt-based catalyst is 51.8wt%;

[0077] That is, in the preparation method of the cobalt-based catalyst, the flow rate of adding the cobalt chloride hexahydrate solution into the ammonium bicarbonate aqueous solution is 1.4 kg / h, and the rest is the same as in Example 1.

[0078] Example 7

[0079] This embodiment provides a cobalt-based catalyst, except that the chemical formula of the cobalt-based catalyst is Co(OH) 0.6 (CO3) 0.7 , based on the mass of the cobalt-based catalyst as 100%, the mass fraction of cobalt in the cobalt-based catalyst is 53.0wt%;

[0080] That is, in the preparation method of the cobalt-based catalyst, the flow rate of adding the cobalt chloride hexahydrate solution into the ammonium bicarbonate aqueous solution is 21 kg / h, and the rest is the same as in Example 1.

[0081] Comparative Example 1

[0082] This comparative example provides a cobalt-based catalyst, which has a three-dimensional porous flower-like structure and a specific surface area of ​​238 m 2 / g, the average particle size is 15.8nm, and the half-peak width of the (020) crystal plane is 0.562;

[0083] That is, in the preparation method of the cobalt-based catalyst, except that the coprecipitation reaction time is 2 hours, the rest is the same as in Example 1.

[0084] The cobalt-based catalyst provided in this embodiment was tested using a scanning electron microscope, and the SEM image of the cobalt-based catalyst provided in this embodiment at a magnification of 20,000 times was obtained. Figure 4 As shown; the SEM image at a magnification of 30,000 times is as shown Figure 5 shown.

[0085] Comparative Example 2

[0086] This comparative example provides a cobalt-based catalyst, which has a three-dimensional porous sponge-like aggregate structure and a specific surface area of ​​241 m 2 / g, the average particle size is 16.2nm., the half-peak width of (020) crystal plane is 0.598;

[0087] That is, in the preparation method of the cobalt-based catalyst, except that the coprecipitation reaction time is 4 hours, the rest is the same as in Example 1.

[0088] The cobalt-based catalyst provided in this embodiment was tested using a scanning electron microscope, and the SEM image of the cobalt-based catalyst provided in this embodiment at a magnification of 20,000 times was obtained. Figure 6 As shown; the SEM image at a magnification of 30,000 times is as shown Figure 7 shown.

[0089] Comparative Example 3

[0090] This comparative example provides a cobalt-based catalyst, which has a three-dimensional granular agglomerated structure and a specific surface area of ​​241 m 2 / g, the average particle size is 16.1nm., the half-peak width of (020) crystal plane is 0.603;

[0091] That is, in the preparation method of the cobalt-based catalyst, except that the coprecipitation reaction time is 8 hours, the rest is the same as in Example 1.

[0092] The cobalt-based catalyst provided in this embodiment was tested using a scanning electron microscope, and the SEM image of the cobalt-based catalyst provided in this embodiment at a magnification of 10,000 times was obtained. Figure 8 As shown; the SEM image at a magnification of 20,000 times is as shown Figure 9 shown.

[0093] The catalytic activity of the cobalt-based catalysts provided in the above embodiments and comparative examples for hydrogen electrolysis was tested. The catalytic activity was tested as follows: in a standard three-electrode system, the working electrode was a glassy carbon electrode (3 mm in diameter) with a loading of 1.0 mg / cm2 of the cobalt-based catalyst (provided in the above embodiments and comparative examples), the counter electrode was a platinum sheet, the reference electrode was a Hg / HgO electrode, and the electrolyte was a 1.0 mol / L KOH solution. The polarization curve of -0.8 to 0.2 V vs. RHE was tested by linear sweep voltammetry (LSV, scan rate 5 mV / s) at 25 ° C, and 10 mA cm was recorded. -2 The hydrogen evolution overpotentials at different current densities are shown in Table 1.

[0094] Table 1

[0095]

[0096]

[0097] From Table 1, we can get:

[0098] (1) The cobalt-based catalysts provided in Examples 1 to 3 of the present invention have a three-dimensional nanofiber network structure, a small average particle size, and a large specific surface area, and thus have a high number of active sites, thereby exhibiting excellent catalytic activity;

[0099] (2) By comparing Example 1 with Examples 4 and 5, it can be seen that in the preparation method of the cobalt-based catalyst of the present invention, the air flow rate in the air injection will affect the specific surface area and average particle size of the cobalt-based catalyst, thereby affecting the number of catalytic sites and catalytic activity of the cobalt-based catalyst; when the air flow rate in the air injection is 3 to 5 m 3 When the air flow rate is 3-5 m³ / h, the cobalt-based catalyst has stronger catalytic activity. This is because when the air flow rate is 3-5 m³ / h, the shear dispersion effect of the airflow and the tendency of particle agglomeration reach a balance. It can not only suppress excessive particle agglomeration through moderate impact force to form a loose and porous hierarchical structure, but also avoid strong airflow destroying the integrity of the particles, thus obtaining a cobalt-based catalyst with excellent catalytic performance.

[0100] (3) By comparing Example 1 with Examples 6 and 7, it can be seen that in the present invention, in the cobalt-based catalyst, the mass fraction of cobalt in the cobalt-based catalyst affects the performance of the cobalt-based catalyst; when the mass fraction of cobalt in the cobalt-based catalyst is 48.1-51.2 wt% based on the mass of the cobalt-based catalyst, the cobalt-based catalyst has a stronger catalytic activity. This is because when the mass fraction of cobalt is 48.1-51.2 wt%, the coordination effect between the cobalt element and the hydroxyl group and the carbonate group reaches an optimal balance, which not only provides sufficient catalytic active sites through a moderate cobalt content, but also regulates the electronic structure and surface defects by the coordination effect, thereby accelerating the charge transfer speed; in addition, when the mass fraction of cobalt is 48.1-51.2 wt%, the cobalt-based catalyst can maintain a fibrous porous morphology, ensuring that the cobalt-based catalyst has more catalytic sites;

[0101] (4) By comparing Example 1 with Comparative Examples 1 to 3, it can be seen that the cobalt-based catalyst provided by the present invention has a three-dimensional nanofiber network structure, and the agglomeration phenomenon is greatly improved, so it has a higher specific surface area and can expose more active sites, thus having excellent catalytic performance;

[0102] In the preparation method provided by the present invention, a cobalt-based catalyst with a high specific surface area and a nanofiber three-dimensional network structure can be prepared through only simple steps, and the preparation process is simple and the preparation cost is low.

[0103] The above description is only a specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Those skilled in the art should understand that any changes or substitutions that can be easily thought of by those skilled in the art within the technical scope disclosed by the present invention fall within the protection scope and disclosure scope of the present invention.

Claims

1. A cobalt-based catalyst, characterized in that The chemical formula of the cobalt-based catalyst is Co(OH) x (CO3) 1-0.5x , x is not higher than 2, and the cobalt-based catalyst has a nanofiber three-dimensional network structure.

2. The cobalt-based catalyst according to claim 1, characterized in that The specific surface area of ​​the cobalt-based catalyst is 235 to 255 m 2 / g.

3. The cobalt-based catalyst according to claim 1, characterized in that The average particle size of the cobalt-based catalyst is 15.0 to 23.5 nm; Preferably, the half-peak width of the (020) crystal plane of the cobalt-based catalyst is 0.547 to 0.

691.

4. The cobalt-based catalyst according to claim 1, characterized in that Based on the mass of the cobalt-based catalyst as 100%, the mass fraction of cobalt in the cobalt-based catalyst is 48.1-51.2 wt%.

5. A method for preparing the cobalt-based catalyst according to any one of claims 1 to 4, characterized in that: The preparation method comprises: The cobalt salt solution and the precipitant solution are continuously added to the reaction base solution to carry out a coprecipitation reaction for 10 to 15 hours to obtain a cobalt-based catalyst; The cobalt salt solution is added to the reaction base solution in a manner including air injection.

6. The preparation method according to claim 5, characterized in that The flow rate of the cobalt salt solution added to the reaction base liquid is 1.6-1.8 kg / h; Preferably, the cobalt ion concentration in the cobalt salt solution is 110-130 g / L; Preferably, the air flow rate in the air injection is 3 to 5 m 3 / h.

7. The preparation method according to claim 5, characterized in that The flow rate of the precipitant solution added to the reaction base liquid is 2.9-3~1kg / h; Preferably, the concentration of the precipitant in the precipitant solution is 220-260 g / L; Preferably, the precipitant in the precipitant solution comprises sodium carbonate and / or sodium bicarbonate; Preferably, the pH of the reaction base solution is 8.3 to 8.6; Preferably, the reaction base liquid comprises an aqueous solution of ammonium bicarbonate.

8. The preparation method according to claim 5, characterized in that During the coprecipitation reaction, the pH is controlled at 7.3-7.5, and the reaction is stirred at a rotation speed of 400-550 rpm.

9. The preparation method according to claim 5, characterized in that The preparation method comprises: A cobalt salt solution having a cobalt ion concentration of 110 to 130 g / L and a precipitant solution having a concentration of 220 to 260 g / L are continuously added to an aqueous ammonium bicarbonate solution having a pH of 8.3 to 8.6, and a coprecipitation reaction is carried out for 10 to 15 hours. During the coprecipitation reaction, the pH is controlled at 7.3 to 7.5 and the stirring speed is 400 to 550 rpm to obtain a cobalt-based catalyst. The flow rate of the cobalt salt solution added to the reaction base liquid is 1.6-1.8 kg / h, and the cobalt salt solution is added to the reaction base liquid in a manner including air injection, and the air flow rate in the air injection is 3-5 m 3 / h.

10. Use of the cobalt-based catalyst according to any one of claims 1 to 4, characterized in that: The cobalt-based catalyst is used for catalytic oxidation or water electrolysis to produce hydrogen.

Images