La-Ce double-doped Co3S4 material as well as preparation method and application thereof

Abstract

The invention provides a La-Ce double-doped Co3S4 material as well as a preparation method and application thereof, and belongs to the technical field of electrolyzed water. A sulfide structure with high conductivity and catalytic activity is constructed through sulfur and cobalt in Co3S4, and a basic active site is provided for an oxygen evolution reaction; lanthanum and cerium are used for adjusting the d-band center of cobalt, so that the reaction energy barrier is reduced, and the catalytic activity is improved; the oxygen vacancy can be increased by doping cerium, and the catalytic activity is improved; the ion radiuses of lanthanum and cerium are relatively large, so that the structure stability can be maintained, and the interface charge transfer is optimized; the specific microstructure greatly increases the specific surface area of the material, increases active sites, and further improves the catalytic activity.

Description

Technical Field

[0001] The present invention belongs to the technical field of electrolyzed water, and particularly relates to a La-Ce double-doped Co 3 S 4 material and its preparation method and application. Background Art

[0002] Hydrogen production by electrolyzing water using renewable clean energy is a technology that can be produced on a large scale, has good economic benefits and conforms to the concept of green development, and has good development prospects.

[0003] The process of electrocatalytic water splitting includes two half-reactions, an anodic reaction and a cathodic reaction. In these two reactions, the anodic reaction usually requires overcoming a higher energy barrier. Using an efficient electrocatalyst can lower the reaction energy barrier, increase the reaction rate, and reduce the cost of hydrogen production. Currently, the catalysts used are mostly noble metal catalysts. These catalysts have a small stockpile of resources and are expensive, and cannot meet the requirements for large-scale applications. Therefore, developing efficient catalysts that can be used on a large scale has become a hot topic for scholars to study.

[0004] Transition metal oxides / hydroxides, metal carbides / nitrides, and metal sulfides have been proven to have good catalytic activity. Among them, Co 3 S 4 is widely used in electrolyzed water because of its low cost and good catalytic activity. However, the initial overpotential of the Co 3 S 4 products in the existing technology is still above 1.6V and needs to be further reduced. Summary of the Invention

[0005] The purpose of the present invention is to provide a La-Ce double-doped Co 3 S 4 material and its preparation method and application. The present invention provides a La-Ce double-doped Co 3 S 4 material with excellent catalytic oxygen evolution activity at a lower initial overpotential.

[0006] In order to achieve the above invention purpose, the present invention provides the following technical solutions:

[0007] The present invention provides a La-Ce double-doped Co 3 S 4 material, including: Co 3 S 4 and La and Ce doped in the Co 3 S 4 ; the La-Ce double-doped Co 3 S 4The molar ratio of La, Ce, and Co in the material is (0.5 - 1):(0.5 - 1):(8 - 38); the La-Ce double-doped Co 3 S 4 The microstructure of the material is a three-dimensional flower-like structure assembled by nanorods.

[0008] The present invention also provides the La-Ce double-doped Co 3 S 4 material preparation method, including:

[0009] Mix cobalt source, lanthanum source, cerium source, precipitant, and structure-directing agent with water and carry out hydrothermal synthesis reaction to obtain La / Ce-Co(OH) 2 ; the molar ratio of the cobalt source, precipitant, and structure-directing agent is (8 - 38):(350 - 450):(150 - 170);

[0010] Mix the La / Ce-Co(OH) 2 with the sulfur source solution and carry out sulfidation reaction to obtain La / Ce-Co 3 S 4 intermediate;

[0011] Carry out plasma treatment on the La / Ce-Co 3 S 4 intermediate to obtain La-Ce double-doped Co 3 S 4 material.

[0012] Preferably, the discharge power of the plasma treatment is 200 - 500 W, and the plasma treatment time is 1 - 5 min.

[0013] Preferably, a conductive substrate is added in the hydrothermal synthesis reaction, and the conductive substrate is an electrode material.

[0014] Preferably, the cobalt source is cobalt nitrate hexahydrate, the lanthanum source is lanthanum nitrate hexahydrate, the cerium source is cerium nitrate hexahydrate, the sulfur source is sodium sulfide, the precipitant is urea, and the structure-directing agent is ammonium fluoride.

[0015] Preferably, the molar ratio of the sum of the amounts of the cobalt source, lanthanum source, and cerium source to the amount of the sulfur source is 1:(1 - 6).

[0016] Preferably, the temperature of the hydrothermal synthesis reaction is 110 - 130 °C, and the time is 5 - 7 h.

[0017] Preferably, the temperature of the sulfidation reaction is 110 - 130 °C, and the time is 5 - 7 h.

[0018] The present invention also provides the application of the La-Ce double-doped Co 3 S 4 material as a water electrolysis oxygen evolution catalyst.

[0019] Preferably, the La-Ce double-doped Co 3 S 4 material is loaded on the surface of the electrode material as the working electrode, the saturated calomel electrode is used as the reference electrode, the graphite carbon rod is used as the counter electrode, and the electrolyte during the water decomposition process is a KOH solution.

[0020] The present invention provides a La-Ce double-doped Co 3 S 4 material, comprising: Co 3 S 4 and La and Ce doped in the Co 3 S 4 ; the molar ratio of La, Ce, and Co in the La-Ce double-doped Co 3 S 4 material is (0.5-1):(0.5-1):(8-38); the microstructure of the La-Ce double-doped Co 3 S 4 material is a three-dimensional flower-like structure assembled by nanorods. The present invention constructs a sulfide structure with high conductivity and catalytic activity through sulfur and cobalt in Co 3 S 4 to provide basic active sites for the oxygen evolution reaction; adjusts the d-band center of cobalt by using lanthanum and cerium to lower the reaction energy barrier and improve the catalytic activity; the doping of cerium can also increase oxygen vacancies and improve the catalytic activity; the ionic radii of lanthanum and cerium are relatively large, and can also maintain the structural stability and optimize the interfacial charge transfer; the specific microstructure greatly increases the specific surface area of the material, increases the active sites, and further improves the catalytic activity. The results of the examples show that the La-Ce double-doped Co 3 S 4 material provided by the present invention can catalyze oxygen evolution at an overpotential of 1.5 V and has high catalytic activity. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 is the XRD pattern of the La / Ce-Co 3 S 4 intermediate and the La-Ce double-doped Co 3 S 4 material prepared in Example 1 of the present invention;

[0022] Figure 2 is the La / Ce-Co 3 S 4 intermediate and the La-Ce double-doped Co3 S 4 SEM images of the material, where (a) is La / Ce-Co 3 S 4 Microscopic morphology of the intermediate magnified 1000 times, (b) is La / Ce-Co 3 S 4 Microscopic morphology of the intermediate magnified 5000 times, (c) is La-Ce double-doped Co 3 S 4 Microscopic morphology of the material magnified 1000 times, (d) is La-Ce double-doped Co 3 S 4 Microscopic morphology of the material magnified 5000 times;

[0023] Figure 3 La-Ce double-doped Co prepared in Example 1 of the present invention 3 S 4 TEM image of the material;

[0024] Figure 4 La-Ce double-doped Co prepared in Example 1 of the present invention 3 S 4 Element mapping image of the material;

[0025] Figure 5 La-Ce double-doped Co prepared in Examples 1-5 of the present invention 3 S 4 Voltammogram of the material;

[0026] Figure 6 La-Ce double-doped Co prepared in Examples 2, 6, and 7 of the present invention 3 S 4 Voltammogram of the material;

[0027] Figure 7 La-Ce double-doped Co prepared in Examples 2, 8, and 9 of the present invention 3 S 4 Voltammogram of the material;

[0028] Figure 8 La-Ce double-doped Co prepared in Example 2 and Comparative Example 1 of the present invention 3 S 4 Voltammogram of the material. Detailed implementation mode

[0029] For all raw materials of the present invention, there is no particular limitation on their sources, and they can be purchased on the market or prepared by conventional methods well-known to those skilled in the art.

[0030] For all raw materials of the present invention, there is no particular limitation on their purity, and analytically pure raw materials are preferably used in the present invention.

[0031] The present invention provides a La-Ce dual-doped Co 3 S 4 material, comprising: Co 3 S 4 and La and Ce doped in the Co 3 S 4 ; the molar ratio of La, Ce, and Co in the La-Ce dual-doped Co 3 S 4 material is (0.5 - 1):(0.5 - 1):(8 - 38); the microstructure of the La-Ce dual-doped Co 3 S 4 material is a three-dimensional flower-like structure assembled by nanorods.

[0032] The La-Ce dual-doped Co 3 S 4 material provided by the present invention comprises Co 3 S 4 . In the present invention, a sulfide structure with high conductivity and catalytic activity is constructed by sulfur and cobalt in Co 3 S 4 to provide a basic active site for the oxygen evolution reaction.

[0033] The La-Ce dual-doped Co 3 S 4 material provided by the present invention further comprises La and Ce doped in the Co 3 S 4 . In the present invention, lanthanum and cerium are used to adjust the d-band center of cobalt, reduce the reaction energy barrier, and improve the catalytic activity; the doping of cerium can also increase oxygen vacancies and improve the catalytic activity; the ionic radii of lanthanum and cerium are relatively large, and can also maintain the structural stability and optimize the interfacial charge transfer.

[0034] In the present invention, the molar ratio of La, Ce, and Co in the La-Ce dual-doped Co 3 S 4 material is (0.5 - 1):(0.5 - 1):(8 - 38), preferably 1:1:(8 - 38), more preferably 1:1:(15 - 25); as an embodiment of the present invention, the La-Ce dual-doped Co 3 S 4The molar ratio of La, Ce, and Co in the material can be 1:1:8, 1:1:10, 1:1:18, 1:1:20, 1:1:28, 1:1:33, or 1:1:38. When the molar ratio of La, Ce, and Co is within the above range, the functions of lanthanum and cerium can be effectively exerted, and at the same time, excessive dosage is avoided from affecting Co 3 S 4 structure and causing a decrease in catalytic activity.

[0035] In the present invention, the La-Ce dual-doped Co 3 S 4 material has a microstructure of three-dimensional flower-like assembled by nanorods. The La-Ce dual-doped Co 3 S 4 material provided by the present invention, the nanorods assembled into a three-dimensional flower-like are independent nanorods, while the material obtained by the traditional hydrothermal synthesis reaction is also nanorods but there are a large number of clusters between the nanorods; the dispersed nanorod structure can greatly increase the specific surface area of the material, increase the active sites, and further improve the catalytic activity of the material.

[0036] In the present invention, high-conductivity and catalytic-activity sulfide structures are constructed by sulfur and cobalt in Co 3 S 4 to provide basic active sites for the oxygen evolution reaction; lanthanum and cerium are used to adjust the d-band center of cobalt, reduce the reaction energy barrier, and improve the catalytic activity; the doping of cerium can also increase oxygen vacancies and improve the catalytic activity; the ionic radii of lanthanum and cerium are relatively large, and can also maintain the structural stability and optimize the interfacial charge transfer; the specific microstructure greatly increases the specific surface area of the material, increases the active sites, and further improves the catalytic activity.

[0037] The present invention also provides a preparation method of the La-Ce dual-doped Co 3 S 4 material described in the above technical solution, including:

[0038] Mixing a cobalt source, a lanthanum source, a cerium source, a precipitant, and a structure-directing agent with water and then performing a hydrothermal synthesis reaction to obtain La / Ce-Co(OH) 2 ; the molar ratio of the cobalt source, the precipitant, and the structure-directing agent is (8-38):(350-450):(150-170);

[0039] Mixing the La / Ce-Co(OH) 2 with a sulfur source solution and then performing a sulfidation reaction to obtain a La / Ce-Co 3 S 4 intermediate;

[0040] Mixing the La / Ce-Co 3 S4 The intermediate is subjected to plasma treatment to obtain La-Ce double-doped Co 3 S 4 material.

[0041] In the present invention, a cobalt source, a lanthanum source, a cerium source, a precipitating agent, and a structure-directing agent are mixed with water and then subjected to a hydrothermal synthesis reaction to obtain La / Ce-Co(OH) 2 .

[0042] In the present invention, the cobalt source is preferably cobalt nitrate hexahydrate, the lanthanum source is preferably lanthanum nitrate hexahydrate, the cerium source is preferably cerium nitrate hexahydrate, the precipitating agent is preferably urea, and the structure-directing agent is preferably ammonium fluoride. Using the above raw materials in the present invention is beneficial to obtaining a material with a three-dimensional flower-like microstructure assembled by nanorods, further improving the specific surface area of the material.

[0043] In the present invention, the molar ratio of the cobalt source, the precipitating agent, and the structure-directing agent is (8-38):(350-450):(150-170), preferably (8-38):400:160, more preferably (15-25):400:160; as an embodiment of the present invention, the molar ratio of the cobalt source, the precipitating agent, and the structure-directing agent can be 8:400:160, 18:400:160, 20:400:160, 28:400:160, 33:400:160 or 38:400:160. The dosage relationship of the cobalt source, the precipitating agent, and the structure-directing agent affects the morphology of the product. When the molar ratio of the cobalt source, the precipitating agent, and the structure-directing agent is within the above range, a material with a three-dimensional flower-like microstructure assembled by nanorods can be obtained, improving the specific surface area of the material.

[0044] The present invention has no special requirements for the specific mixing method, and the conventional mixing methods in the art can be used. As an embodiment of the present invention, mixing can be carried out by stirring, and the stirring time can be 15 min.

[0045] The present invention has no special requirements for the concentration of the raw materials in the hydrothermal synthesis reaction, and the conventional raw material concentrations in the art can be used. In the examples of the present invention, 0.45 mmol of the cobalt source, 0.025 mmol of the lanthanum source, 0.025 mmol of the cerium source, 10 mmol of the precipitating agent, and 4 mmol of the structure-directing agent are dissolved in 30 mL of deionized water (DI) to prepare a solution.

[0046] In the present invention, a conductive substrate is preferably further added to the hydrothermal synthesis reaction, and the conductive substrate is preferably an electrode material. The present invention does not particularly limit the specific type of the electrode material, and conventional electrode materials in the art can be used. In the examples of the present invention, the electrode material is nickel foam. Adding an electrode material to the hydrothermal synthesis reaction can in-situ generate a product on the electrode material. When the material is used as an oxygen evolution catalyst, the catalytic activity can be further improved.

[0047] The present invention does not particularly limit the specifications of the conductive substrate, and conventional specifications of the conductive substrate in the art can be used. In the examples of the present invention, the specifications of the conductive substrate are 1 cm × 4 cm. As an embodiment of the present invention, the conductive substrate can be pretreated before use, and the pretreatment can include hydrochloric acid cleaning, ethanol cleaning, water washing, and drying in sequence; the concentration of the hydrochloric acid can be 2 mol / L, ultrasonic cleaning can be used during cleaning, the time for each cleaning can be 10 min, and the drying temperature can be 60 °C. By pretreatment, the oxide layer on the surface of the conductive substrate can be removed, the bonding effect between the material and the substrate can be improved, and the catalytic activity of the material can be further improved.

[0048] In the present invention, the temperature of the hydrothermal synthesis reaction is preferably 110 - 130 °C, more preferably 115 - 125 °C; as an embodiment of the present invention, the temperature of the hydrothermal synthesis reaction can be 112 °C, 117 °C, 120 °C, 122 °C, 126 °C, or 128 °C. When the temperature of the hydrothermal synthesis reaction is within the above range, it is beneficial to obtain a material with a three-dimensional flower-like microstructure assembled by nanorods, and the specific surface area of the material can be further increased.

[0049] In the present invention, the time of the hydrothermal synthesis reaction is preferably 5 - 7 h, more preferably 5.5 - 6.5 h; as an embodiment of the present invention, the time of the hydrothermal synthesis reaction can be 5 h, 5.5 h, 6 h, 6.5 h, or 7 h. When the time of the hydrothermal synthesis reaction is within the above range, it is beneficial to obtain a material with a three-dimensional flower-like microstructure assembled by nanorods, and the specific surface area of the material can be further increased.

[0050] The present invention does not particularly limit the device for the hydrothermal synthesis reaction, and a conventional device for the hydrothermal synthesis reaction in the art can be used. In the examples of the present invention, the hydrothermal synthesis reaction is carried out in a 50 mL Teflon stainless steel autoclave.

[0051] After the hydrothermal synthesis reaction is completed, the present invention preferably washes and dries the obtained product in sequence to obtain La / Ce-Co(OH) 2The present invention has no special requirements for the specific operations of the cleaning and drying, and conventional methods in the art can be adopted. In the embodiments of the present invention, the cleaning is DI cleaning repeated three times; the drying is drying, and the drying conditions can be drying at 60°C for 6 hours in a sealed environment.

[0052] After obtaining La / Ce-Co(OH) 2 the present invention mixes the La / Ce-Co(OH) 2 with a sulfur source solution and then conducts a sulfidation reaction to obtain La / Ce-Co 3 S 4 intermediate.

[0053] In the present invention, the sulfur source is preferably sodium sulfide. Sodium sulfide as the sulfur source can conduct the sulfidation reaction at a relatively low temperature, and S 2- has a strong affinity for metal ions, which is beneficial to the progress of the reaction. The present invention has no special requirements for the concentration of the sulfur source solution, as long as the sulfidation reaction can proceed normally. In the embodiments of the present invention, the sulfur source solution is obtained by dissolving 0.3 mmol of sodium sulfide in 30 mL of DI and stirring until the sodium sulfide is completely dissolved.

[0054] In the present invention, the molar ratio of the sum of the amounts of the cobalt source, lanthanum source, and cerium source to the amount of the sulfur source is preferably 1:(1-6), more preferably 1:(2-3); as an embodiment of the present invention, the molar ratio of the sum of the amounts of the cobalt source, lanthanum source, and cerium source to the amount of the sulfur source can be 1:1.3, 1:2.6, 1:3.5, 1:4, 1:4.5, or 1:5.2. When the molar ratio of the sum of the amounts of the cobalt source, lanthanum source, and cerium source to the amount of the sulfur source is within the above range, it is beneficial to construct a sulfide structure with high conductivity and high catalytic activity, further expose the active sites, and improve the catalytic activity.

[0055] In the present invention, the temperature of the sulfidation reaction is preferably 110-130°C, more preferably 115-125°C; as an embodiment of the present invention, the temperature of the sulfidation reaction can be 112°C, 117°C, 120°C, 122°C, 126°C, or 128°C. When the temperature of the sulfidation reaction is within the above range, it is beneficial to construct a sulfide structure with high conductivity and high catalytic activity, expose more active sites, and improve the catalytic activity.

[0056] In the present invention, the time of the sulfidation reaction is preferably 5-7 hours, more preferably 5.5-6.5 hours; as an embodiment of the present invention, the time of the sulfidation reaction can be 5 hours, 5.5 hours, 6 hours, 6.5 hours, or 7 hours. When the time of the sulfidation reaction is within the above range, it is beneficial to construct a sulfide structure with high conductivity and high catalytic activity, expose more active sites, and improve the catalytic activity.

[0057] The present invention does not particularly limit the device for the vulcanization reaction, and a conventional device for the vulcanization reaction in the art can be used. In the examples of the present invention, the vulcanization reaction is carried out in a 50 mL Teflon stainless steel reactor.

[0058] After the vulcanization reaction is completed, the present invention preferably washes and dries the obtained product in sequence to obtain La / Ce-Co 3 S 4 intermediate. The present invention does not particularly limit the specific operations of the washing and drying, and conventional methods in the art can be used. In the examples of the present invention, the washing is DI washing, which is repeated 3 times, and the drying is drying in an oven at a temperature of 60 °C for 6 h.

[0059] After obtaining La / Ce-Co 3 S 4 intermediate, the present invention performs plasma treatment on the La / Ce-Co 3 S 4 intermediate to obtain La-Ce double-doped Co 3 S 4 material.

[0060] In the present invention, the discharge power of the plasma treatment is preferably 200 - 500 W, more preferably 250 - 350 W; as an embodiment of the present invention, the discharge power of the plasma treatment can be 200 W, 250 W, 300 W, 350 W, 400 W or 500 W. When the discharge power of the plasma treatment is within the above range, the nanorod-shaped materials of the clusters can be dispersed into independent nanorods one by one, which is beneficial to constructing more active sites on the material surface and further improving the catalytic activity.

[0061] In the present invention, the time of the plasma treatment is preferably 1 - 5 min, more preferably 2 - 3 min; as an embodiment of the present invention, the time of the plasma treatment can be 1 min, 2 min, 3 min, 4 min or 5 min. When the time of the plasma treatment is within the above range, the nanorod-shaped materials of the clusters can be dispersed into independent nanorods one by one, which is beneficial to exposing more active sites on the material surface and further improving the catalytic activity.

[0062] The present invention does not have special requirements for other parameters of the plasma treatment, and conventional parameters in the art can be used. In the examples of the present invention, the sample is placed on a porcelain boat during the plasma treatment, and argon is introduced for protection.

[0063] The present invention utilizes the characteristic that the morphology of the product is easily controlled in the hydrothermal synthesis reaction. By controlling the dosage relationship of raw materials, a material with a three-dimensional flower-like structure assembled by nanorods is obtained, which is beneficial to increasing the specific surface area of the material, exposing more active sites, and further enhancing the catalytic activity of the material. A sulfide structure with high conductivity and high catalytic activity is constructed through a sulfidation reaction to provide basic active sites. Through plasma treatment, the clustered nanorod-like material can be dispersed into individual nanorods, exposing more active sites on the surface of the material and further improving the catalytic activity of the material.

[0064] The present invention also provides the application of the La-Ce double-doped Co 3 S 4 material as a water splitting oxygen evolution catalyst.

[0065] In the present invention, it is preferably to load the La-Ce double-doped Co 3 S 4 material on the surface of the electrode material as the working electrode, the saturated calomel electrode as the reference electrode, the graphite carbon rod as the counter electrode, and the electrolyte during the water splitting process is a KOH solution. As an embodiment of the present invention, the concentration of the KOH solution can be 1 mol / L.

[0066] Next, the technical solutions in the present invention will be clearly and completely described in conjunction with the embodiments in the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments in the present invention without creative efforts shall fall within the protection scope of the present invention.

[0067] Example 1

[0068] A La-Ce double-doped Co 3 S 4 material, wherein the molar ratio of La, Ce, and Co is 1:1:18; the La-Ce double-doped Co 3 S 4 material is coated on the surface of nickel foam (NF), and the microscopic morphology is a three-dimensional flower-like assembled by nanorods; its preparation method is as follows:

[0069] 1) Take NF slices (1 cm × 4 cm) and ultrasonically treat them with 2.0 mol / L hydrochloric acid for 10 minutes to remove the oxidized surface, and then ultrasonically treat them with ethanol and DI for 10 minutes respectively, and dry at 60 °C;

[0070] 2) Dissolve cobalt nitrate hexahydrate (0.45 mmol, 0.131 g), lanthanum nitrate hexahydrate (0.025 mmol, 0.011 g), cerium nitrate hexahydrate (0.025 mmol, 0.011 g), urea (10 mmol, 0.6 g) and ammonium fluoride (4 mmol, 0.148 g) in 30 mL of DI to prepare a solution. The molar ratio of the cobalt source, precipitant, and structure-directing agent is 18:400:160. Stir the mixture thoroughly for 15 minutes, then place the treated NF in a 50 mL Teflon-lined stainless steel autoclave and slowly pour the stirred solution along the wall;

[0071] 3) After sealing the autoclave, heat it at 120 °C for 6 h, cool it to room temperature, take out the product from the autoclave, wash it 3 times repeatedly with DI, and dry it in a sealed environment at 60 °C for 6 h to obtain La / Ce-Co(OH) 2 ;

[0072] 4) Add sodium sulfide (0.1 g, 1.3 mmol) to 30 mL of DI solution, stir to dissolve it completely, place the dried La / Ce-Co(OH) 2 against the wall in a 50 mL Teflon-lined stainless steel autoclave, slowly pour in the sodium sulfide solution, seal the autoclave, react at 120 °C for 6 h, cool it to room temperature, take out the product from the autoclave, wash it 3 times repeatedly with DI, and dry it at 60 °C for 6 h to obtain La / Ce-Co 3 S 4 intermediate;

[0073] 5) Place the dried La / Ce-Co 3 S 4 intermediate flat on a porcelain boat, slowly introduce argon, and perform plasma treatment on the sample for 1 min under the condition of a discharge power of 300 W. The obtained sample is the La-Ce double-doped Co 3 S 4 material, denoted as La / Ce-Co 3 S 4 -plasma 1.

[0074] Use an X-ray diffractometer to detect the La / Ce-Co 3 S 4 intermediate and La-Ce double-doped Co 3 S 4 materials prepared in Example 1 to obtain an XRD pattern, as Figure 1 shown, Figure 1 in which Co 3 S 4 / NF represents the La / Ce-Co 3 S 4 intermediate, La / Ce-Co3 S 4 -plasma / NF represents La-Ce co-doped Co 3 S 4 material. As can be seen from Figure 1 it, the diffraction peaks of the material prepared in Example 1 are in good agreement with the standard card 47-1738, and the phase is Co 3 S 4 , the diffraction peak profiles are sharp, indicating good crystallinity and the absence of other impurity phases, indicating that La and Ce are doped in Co 3 S 4 .

[0075] The obtained La / Ce-Co 3 S 4 intermediate and La-Ce co-doped Co 3 S 4 material prepared in the example were observed by scanning electron microscopy to obtain SEM images as shown in Figure 2 . As can be seen from Figure 2 it, the microscopic morphology of the material after plasma treatment changes from cluster-like rod-shaped nanowires to independent rod-shaped nanowires, greatly increasing the specific surface area of the material and exposing more active sites.

[0076] The obtained La-Ce co-doped Co 3 S 4 material prepared in Example 1 was observed by transmission electron microscopy to obtain TEM images as shown in Figure 3 . As can be seen from Figure 3 it, different positions were selected for magnified observation (red and green frames in the figure), and the measured lattice spacings were 0.29 nm and 0.24 nm, corresponding to the (311) and (400) crystal planes of Co 3 S 4 respectively, which is consistent with the XRD test results, indicating that the material exists in the phase of Co 3 S 4 .

[0077] The obtained La-Ce co-doped Co 3 S 4 material prepared in Example 1 was tested by energy dispersive spectrometer to obtain element mapping images as shown in Figure 4 . As can be seen from Figure 4 it, the distributions of S, Co, La, and Ce are uniform, indicating that La and Ce are uniformly doped in Co 3 S 4 .

[0078] Example 2

[0079] A kind of La-Ce co-doped Co3 S 4 The materials, raw materials and preparation method are the same as those in Example 1, except that the plasma treatment time is 2 min, denoted as La / Ce-Co 3 S 4 -plasma 2

[0080] Example 3

[0081] A La-Ce double-doped Co 3 S 4 The materials, raw materials and preparation method are the same as those in Example 1, except that the plasma treatment time is 3 min, denoted as La / Ce-Co 3 S 4 -plasma 3

[0082] Example 4

[0083] A La-Ce double-doped Co 3 S 4 The materials, raw materials and preparation method are the same as those in Example 1, except that the plasma treatment time is 4 min, denoted as La / Ce-Co 3 S 4 -plasma 4

[0084] Example 5

[0085] A La-Ce double-doped Co 3 S 4 The materials, raw materials and preparation method are the same as those in Example 1, except that the plasma treatment time is 5 min, denoted as La / Ce-Co 3 S 4 -plasma 5

[0086] Example 6

[0087] A La-Ce double-doped Co 3 S 4 The materials, raw materials and preparation method are the same as those in Example 2, except that the discharge power of the plasma treatment is 200 W, denoted as La / Ce-Co 3 S 4 -plasma 6

[0088] Example 7

[0089] A La-Ce double-doped Co 3 S 4 The materials, raw materials and preparation method are the same as those in Example 2, except that the discharge power of the plasma treatment is 500 W, denoted as La / Ce-Co 3 S4 -plasma 7

[0090] Example 8

[0091] A La-Ce co-doped Co 3 S 4 material, the preparation method is the same as that of Example 2, except that the amount of cobalt nitrate hexahydrate is adjusted to 0.058 g, 0.2 mmol, and the molar ratio of La, Ce, and Co is 1:1:8, denoted as La / Ce-Co 3 S 4 -plasma 8

[0092] Example 9

[0093] A La-Ce co-doped Co 3 S 4 material, the preparation method is the same as that of Example 2, except that the amount of cobalt nitrate hexahydrate is adjusted to 0.058 g, 0.2 mmol, and the molar ratio of La, Ce, and Co is 1:1:38, denoted as La / Ce-Co 3 S 4 -plasma 9

[0094] Comparative Example 1

[0095] A La-Ce co-doped Co 3 S 4 material, the raw materials and preparation method are the same as those of Example 2, except that plasma treatment is not carried out, denoted as La / Ce-Co 3 S 4 -no-plasma

[0096] Application Example

[0097] Using the La-Ce co-doped Co 3 S 4 materials prepared in Examples 1-9 and Comparative Example 1 as the working electrode, the saturated calomel electrode as the reference electrode, and the graphite carbon rod as the counter electrode, using 1 mol / L KOH solution as the electrolyte for electrolysis, and using an electrochemical workstation to plot the voltammetric curves of different materials, as Figures 5 to 8 shown

[0098] It can be seen from Figure 5 that when the plasma treatment time is 1-5 min, the materials can start to have catalytic activity at an overpotential of 1.5 V, significantly reducing the energy barrier of the oxygen evolution reaction and improving the catalytic activity; when the plasma treatment time is 2 min, the materials have the optimal catalytic activity. It can be seen from Figure 6 that when the discharge power of the plasma treatment is 300 W, the materials have the optimal catalytic activity. It can be seen fromFigure 7 It can be seen that when the molar ratio of La, Ce, and Co is 1:1:18, the material has the optimal catalytic activity. From Figure 8 It can be seen that the initial overpotential of the material after plasma treatment has decreased from 1.6 V to 1.5 V, reducing the reaction conditions and improving the catalytic activity.

[0099] The above are only the preferred embodiments of the present invention. It should be noted that for those of ordinary skill in the art, without departing from the principle of the present invention, several improvements and refinements can be made, and these improvements and refinements should also be regarded as the protection scope of the present invention.

Claims

1. A La-Ce dual-doped Co3S4 material, comprising: Co3S4 and La and Ce doped in the Co3S4; the amount ratio of La, Ce and Co in the La-Ce doped Co3S4 material is (0.5-1):(0.5-1):(8-38); the microstructure of the La-Ce doped Co3S4 material is a three-dimensional flower shape assembled by nanorods.

2. The method for preparing the La-Ce dual-doped Co3S4 material according to claim 1, comprising: A cobalt source, a lanthanum source, a cerium source, a precipitant and a structure directing agent are mixed with water and subjected to a hydrothermal synthesis reaction to obtain La / Ce-Co(OH)2; the molar ratio of the cobalt source, the precipitant and the structure directing agent is (8-38):(350-450):(150-170); The La / Ce-Co(OH)2 is mixed with a sulfur source solution and subjected to a sulfurization reaction to obtain a La / Ce-Co3S4 intermediate; The La / Ce-Co3S4 intermediate is subjected to plasma treatment to obtain La-Ce dual-doped Co3S4 material.

3. The preparation method according to claim 2, characterized in that: The discharge power of the plasma treatment is 200-500W, and the time of the plasma treatment is 1-5 minutes.

4. The preparation method according to claim 2 or 3, characterized in that: A conductive substrate is also added into the hydrothermal synthesis reaction, and the conductive substrate is an electrode material.

5. The preparation method according to claim 2, characterized in that: The cobalt source is cobalt nitrate hexahydrate, the lanthanum source is lanthanum nitrate hexahydrate, the cerium source is cerium nitrate hexahydrate, the sulfur source is sodium sulfide, the precipitant is urea, and the structure directing agent is ammonium fluoride.

6. The La-Ce dual-doped Co3S4 material according to claim 2 or 5, characterized in that: The ratio of the sum of the amounts of the cobalt source, the lanthanum source and the cerium source to the amount of the sulfur source is 1:(1-6).

7. The preparation method according to claim 2, characterized in that: The temperature of the hydrothermal synthesis reaction is 110-130° C. and the time is 5-7 hours.

8. The preparation method according to claim 2, characterized in that: The temperature of the vulcanization reaction is 110-130° C. and the time is 5-7 hours.

9. Use of the La-Ce dual-doped Co3S4 material according to claim 1 or the La-Ce dual-doped Co3S4 material prepared by the preparation method according to any one of claims 2 to 8 as a water-decomposing oxygen catalyst.

10. The use according to claim 9, characterized in that: The La-Ce dual-doped Co3S4 material is loaded on the surface of the electrode material as a working electrode, a saturated calomel electrode is a reference electrode, a graphite carbon rod is a counter electrode, and the electrolyte in the water decomposition process is a KOH solution.

Images