Nano cobaltosic oxide and preparation method thereof

Abstract

The invention discloses nano cobaltosic oxide and a preparation method thereof, and belongs to the technical field of new nano materials. The preparation method comprises the following steps: S1, adding an oxidizing agent and a bicarbonate solution into a cobalt salt solution, and uniformly mixing to obtain a mixed solution; and S2, carrying out a hydrothermal reaction on the mixed solution, and carrying out solid-liquid separation, washing and drying on the obtained product to obtain the nano cobaltosic oxide. According to the present invention, the oxidizing agent and the bicarbonate solution are added to the cobalt salt solution, the oxidizing agent oxidizes the divalent cobalt to form the trivalent cobalt complex [Co (CO3) 3] 3 <->, the trivalent cobalt complex [Co (CO3) 3] 3 <-> is subjected to pyrolysis under the hydrothermal condition to obtain the cobaltosic oxide nanometer material with characteristics of high purity and uniform particle size, the preparation method is simple, the raw materials are cheap and easily available, and the preparation method is suitable for industrial production. The method is suitable for industrial large-scale production, so that the method has a relatively good industrial application prospect.

Description

Technical Field

[0001] The invention belongs to the technical field of new nano materials, and particularly relates to nano cobalt tetroxide and a preparation method thereof. Background Art

[0002] Nano-cobalt tetroxide is an important functional material with unique physical and chemical properties and is widely used in many fields. Due to its good empty electron orbits, nano-cobalt tetroxide is easy to fuse with electrons and exhibits excellent catalytic performance. It has important application value in heterogeneous catalysis, anode materials for lithium-ion batteries, solar energy absorption materials and pigments. At present, the main methods for preparing nano-cobalt tetroxide include high-temperature decomposition, redox method, electrochemical deposition method, etc. In all of the above methods, a precursor is first prepared, and then calcined to obtain nano-cobalt tetroxide.

[0003] For example, a method for preparing nano-cobalt tetroxide is disclosed in Chinese patent application document CN111717937A, which comprises mixing cobalt chloride with urea and glycerol to obtain a mixed solution, moving into a reactor, utilizing hydrothermal reaction to prepare a cobalt carbonate precursor, and then calcining at high temperature to obtain micron-sized cobalt tetroxide, and then wet-milling the nano-cobalt tetroxide using anhydrous ethanol as a ball milling solvent. However, this process is relatively complex and is difficult to avoid the impurities brought by grinding. Chinese patent application document CN118579848A discloses a method for preparing a nano-cobalt oxide electrode material, which comprises utilizing a cobalt salt, a precipitation agent, and a surfactant to prepare a nano-cobalt carbonate precursor in a multiphase interface reactor, and then calcining at high temperature to obtain nano-cobalt tetroxide. However, this process is complex and requires more expensive raw materials.

[0004] In view of this, it is necessary to provide a new method for preparing nano-cobalt tetroxide to solve the shortcomings of the existing technology. Summary of the Invention

[0005] The present invention aims to provide a nano-cobalt tetroxide and a preparation method thereof, so as to solve the problems of the existing nano-cobalt tetroxide preparation methods, such as the complicated process and the uneven particle size of the prepared nano-cobalt tetroxide.

[0006] In a first aspect, the present invention provides a method for preparing nano-cobalt tetroxide, comprising the following steps: S1, adding an oxidant and a bicarbonate solution to a cobalt salt solution, and mixing them uniformly to obtain a mixed solution; S2, subjecting the mixed solution to a hydrothermal reaction, and subjecting the obtained product to solid-liquid separation, washing, and drying to obtain nano-cobalt tetroxide; wherein, in step S1, the oxidant comprises a hydrogen peroxide solution.

[0007] In the present invention, after adding an oxidant and a bicarbonate solution to a cobalt salt solution, wherein the oxidant oxidizes the divalent cobalt to form a trivalent cobalt complex [Co(CO3)3] 3- , and pyrolyze under hydrothermal conditions to obtain cobalt tetroxide nanomaterials with high purity and uniform particle size. In addition, the preparation method of the present invention is simple, the raw materials are cheap and easy to obtain, and it is suitable for industrial large-scale production.

[0008] In some embodiments, in step S1, the molar concentration of the cobalt salt solution is 2-2.5 mol / L, the mass concentration of the oxidant is 25-35%, and the molar concentration of the bicarbonate solution is 2.2-2.7 mol / L; and the volume ratio of the cobalt salt solution, the oxidant, and the bicarbonate solution is (25-35):(6-25):(50-60).

[0009] In some embodiments, in step S1, the cobalt salt solution includes at least one of a cobalt chloride solution, a cobalt sulfate solution, and a cobalt nitrate solution.

[0010] In some embodiments, in step S1, the bicarbonate solution includes at least one of an ammonium bicarbonate solution, a sodium bicarbonate solution, and a potassium bicarbonate solution.

[0011] In some embodiments, in step S1, mixing uniformly specifically includes: mixing for 0.5-1.5 hours.

[0012] In some embodiments, in step S2, the hydrothermal reaction specifically includes: the hydrothermal reaction temperature is 160-240° C., and the time is 3-15 hours.

[0013] In some embodiments, in step S2, washing and drying specifically include: first washing with deionized water for 3-5 times, and then drying at a constant temperature.

[0014] In some embodiments, constant temperature drying specifically includes: drying at a temperature of 60-80° C. for 10-15 hours.

[0015] In a second aspect, the present invention provides a nano-cobalt tetroxide, which is prepared by any of the above preparation methods.

[0016] The nanometer cobalt tetroxide provided by the present invention has high purity and uniform particle size, and therefore has good industrial application prospects.

[0017] In some embodiments, the particle size of nano-cobalt trioxide is 50-700 nm.

[0018] The beneficial effects of the present invention are as follows: Different from the prior art, the present invention adds an oxidant and a bicarbonate solution to a cobalt salt solution, wherein the oxidant oxidizes the divalent cobalt to form a trivalent cobalt complex [Co(CO3)3] 3- , and pyrolysis under hydrothermal conditions to obtain cobalt oxide nanomaterials with high purity and uniform particle size. In addition, the preparation method of the present invention is simple, the raw materials are cheap and easy to obtain, and it is suitable for industrial large-scale production. Therefore, it has good industrial application prospects. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 This is a flow chart of the preparation method of nano-cobalt tetroxide in the present invention; Figure 2 is the XRD pattern of the sample prepared in Example 1 of the present invention; Figure 3 is the XRD pattern of the sample prepared in Example 2 of the present invention; Figure 4 This is the XRD pattern of the sample prepared in Comparative Example 1 of the present invention. DETAILED DESCRIPTION

[0020] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the embodiments described are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0021] For experimental methods in the examples where specific conditions are not specified, generally conventional conditions and conditions described in the manual or conditions recommended by the manufacturer were followed. The general equipment, materials, reagents, etc. used were all commercially available unless otherwise specified.

[0022] Currently, the existing preparation methods of nano-cobalt tetroxide have problems such as complex process and uneven particle size of the prepared nano-cobalt tetroxide.

[0023] In order to solve the problems of complex process and uneven particle size of the prepared nano-cobalt tetroxide in the existing preparation method of nano-cobalt tetroxide, the present invention provides a nano-cobalt tetroxide and a preparation method thereof.

[0024] In a first aspect, the present invention provides a method for preparing nano-cobalt tetroxide, comprising the following steps: S1, adding an oxidant and a bicarbonate solution to a cobalt salt solution, and mixing them uniformly to obtain a mixed solution; S2, subjecting the mixed solution to a hydrothermal reaction, and subjecting the obtained product to solid-liquid separation, washing, and drying to obtain nano-cobalt tetroxide; wherein, in step S1, the oxidant comprises a hydrogen peroxide solution.

[0025] In the preparation method of nano-cobalt tetroxide provided by the present invention, an oxidant and a bicarbonate solution are added to a cobalt salt solution, wherein the oxidant oxidizes the divalent cobalt to form a trivalent cobalt complex [Co(CO3)3] 3- , and pyrolyze under hydrothermal conditions to obtain cobalt tetroxide nanomaterials with high purity and uniform particle size. In addition, the preparation method of the present invention is simple, the raw materials are cheap and easy to obtain, and it is suitable for industrial large-scale production.

[0026] In some embodiments, in step S1, the molar concentration of the cobalt salt solution is 2-2.5 mol / L, for example, 2 mol / L, 2.1 mol / L, 2.2 mol / L, 2.3 mol / L, 2.4 mol / L, 2.5 mol / L or other values within the range, the mass concentration of the oxidant is 25-35%, for example, 25%, 27%, 30%, 33%, 35% or other values within the range, and the molar concentration of the bicarbonate solution is 2.2-2.7 mol / L, for example, 2.2 mol / L, 2.3 mol / L, 2.4 mol / L, 2.5 mol / L or other values within the range. 2.3mol / L, 2.4mol / L, 2.5mol / L, 2.6mol / L, 2.7mol / L or other values within this range; and the volume ratio of the cobalt salt solution, the oxidant and the bicarbonate solution is (25-35):(6-25):(50-60), for example, 25:6:50, 25:15:55, 25:25:60, 30:6:50, 30:15:55, 30:25:60, 35:6:50, 35:15:55, 35:25:60 or other ratios within this range.

[0027] In the present invention, the inventors have discovered that by controlling the molar concentration of the cobalt salt solution, the mass concentration of the oxidant, the molar concentration of the bicarbonate solution, and the volume ratio of the cobalt salt solution, the oxidant, and the bicarbonate solution within specific ranges, the raw materials can be fully reacted to obtain a cobalt oxide nanomaterial with higher purity and more uniform particle size.

[0028] In some embodiments, in step S1, the cobalt salt solution includes at least one of a cobalt chloride solution, a cobalt sulfate solution, and a cobalt nitrate solution.

[0029] It is understood that the cobalt salt solution can be selected from conventional cobalt salt solutions in the prior art according to actual use needs, as long as the cobalt in the cobalt salt solution is divalent. In the present invention, the cobalt salt solution preferably includes at least one of a cobalt chloride solution, a cobalt sulfate solution, and a cobalt nitrate solution.

[0030] In some embodiments, in step S1, the bicarbonate solution includes at least one of an ammonium bicarbonate solution, a sodium bicarbonate solution, and a potassium bicarbonate solution.

[0031] It is understood that the bicarbonate solution can be selected from conventional bicarbonate solutions in the prior art according to actual use needs, as long as the bicarbonate solution contains bicarbonate. In the present invention, the bicarbonate solution preferably includes at least one of ammonium bicarbonate solution, sodium bicarbonate solution, and potassium bicarbonate solution.

[0032] In some embodiments, in step S1, mixing uniformly specifically includes: mixing time is 0.5-1.5 h, for example, 0.5 h, 0.7 h, 1 h, 1.3 h, 1.5 h or other values within the range.

[0033] In the present invention, by controlling the mixing time within a specific range, the raw materials can be mixed evenly, which facilitates the subsequent hydrothermal reaction.

[0034] In some embodiments, in step S2, the hydrothermal reaction specifically includes: the temperature of the hydrothermal reaction is 160-240°C, for example, it can be 160°C, 180°C, 200°C, 220°C, 240°C or other values within this range, and the time is 3-15h, for example, it can be 3h, 6h, 9h, 12h, 15h or other values within this range.

[0035] In the present invention, by controlling the temperature and time of the hydrothermal reaction within a specific range, the raw materials can be fully reacted to obtain a cobaltous oxide nanomaterial with further improved purity and more uniform particle size.

[0036] In some embodiments, in step S2, washing and drying specifically includes: first washing with deionized water for 3-5 times, and then drying at a constant temperature.

[0037] In the present invention, impurities can be removed by washing and drying, thereby further improving the purity of the prepared nano-cobalt tetroxide.

[0038] In some embodiments, constant temperature drying specifically includes: drying at a temperature of 60-80°C (for example, 60°C, 65°C, 70°C, 75°C, 80°C or other values within the range) for 10-15 hours, for example, 10 hours, 11 hours, 12 hours, 13 hours, 14 hours, 15 hours or other values within the range.

[0039] In a second aspect, the present invention provides a nano-cobalt tetroxide, which is prepared by any of the above preparation methods.

[0040] The nanometer cobalt tetroxide provided by the present invention has high purity and uniform particle size, and therefore has good industrial application prospects.

[0041] In some embodiments, the particle size of nano-cobalt trioxide is 50-700 nm, for example, 50 nm, 100 nm, 200 nm, 300 nm, 400 nm, 500 nm, 600 nm, 700 nm or other values within this range.

[0042] Some specific embodiments are listed below. It should be noted that the embodiments described below are exemplary and are only used to explain the present invention, and should not be understood as limiting the present invention.

[0043] See also Figure 1 , which is a flow chart of the preparation method of nano-cobalt tetroxide in the present invention. Specifically, the preparation method of nano-cobalt tetroxide includes the following steps: S1, adding an oxidizing agent and a bicarbonate solution to a cobalt salt solution, mixing them uniformly, to obtain a mixed solution; S2, subjecting the mixed solution to a hydrothermal reaction, separating the resulting product by solid-liquid separation, washing, and drying to obtain nano-cobalt tetroxide.

[0044] Example 1 A method for preparing nano-cobalt tetroxide comprises the following steps: S1. First, prepare a cobalt chloride solution and an ammonium bicarbonate solution. Specifically, weigh 16.14 g of cobalt chloride hexahydrate into a beaker, and then add 30 ml of deionized water; at the same time, weigh 11.78 g of ammonium bicarbonate into another beaker, and then add 55 ml of deionized water to obtain a cobalt chloride solution and an ammonium bicarbonate solution, respectively; take 6.9 ml of a 30% hydrogen peroxide solution, first add the hydrogen peroxide solution dropwise to the cobalt chloride solution, and then add the ammonium bicarbonate solution dropwise to the cobalt chloride solution, stirring while adding dropwise, mixing evenly, and finally stirring for 1 hour to obtain a mixed solution; S2. The mixed solution obtained in step S1 was transferred into a reactor lined with 200 ml of polytetrafluoroethylene, and the reactor was placed in a rotary oven with the temperature set at 200° C. and the holding time was 6 h. After the reaction was completed, the mixture was naturally cooled to room temperature. The obtained product was subjected to solid-liquid separation, and the precipitate was collected and washed with deionized water for 4-5 times. The precipitate was dried in a blast drying oven at 70° C. for 12 h to obtain nano-cobalt tetroxide.

[0045] The XRD pattern of the nano-cobalt tetroxide prepared in this embodiment is as follows: Figure 2 As shown, from Figure 2 As can be seen from the figure, the main component of the prepared nano-cobalt tetroxide is cobalt tetroxide, containing a small amount of cobalt carbonate. The particle size of the nano-cobalt tetroxide is 100-700nm, and the purity is 50.59%.

[0046] Example 2 A method for preparing nano-cobalt tetroxide comprises the following steps: S1. First, prepare a cobalt chloride solution and an ammonium bicarbonate solution. Specifically, weigh 16.14 g of cobalt chloride hexahydrate into a beaker, and then add 30 ml of deionized water; at the same time, weigh 11.78 g of ammonium bicarbonate into another beaker, and then add 55 ml of deionized water to obtain a cobalt chloride solution and an ammonium bicarbonate solution, respectively; take 20.8 ml of a 30% hydrogen peroxide solution, first add the hydrogen peroxide solution dropwise to the cobalt chloride solution, and then add the ammonium bicarbonate solution dropwise to the cobalt chloride solution, stirring while adding dropwise, mixing evenly, and finally stirring for 1 hour to obtain a mixed solution; S2. The mixed solution obtained in step S1 was transferred into a reactor lined with 200 ml of polytetrafluoroethylene, and the reactor was placed in a rotary oven with the temperature set at 240° C. and the holding time was 9 hours. After the reaction was completed, it was naturally cooled to room temperature. The obtained product was subjected to solid-liquid separation, and the precipitate was collected and washed with deionized water for 4-5 times. The precipitate was dried in a blast drying oven at 70° C. for 12 hours to obtain nano-cobalt tetroxide.

[0047] The XRD pattern of the nano-cobalt tetroxide prepared in this embodiment is as follows: Figure 3 As shown, from Figure 3 It can be seen from the figure that the prepared nano-cobalt tetroxide is composed of cobalt tetroxide and is essentially free of impurities. The particle size of the nano-cobalt tetroxide is 50-300nm and the purity is 98.99%.

[0048] Comparative Example 1 A method for preparing nano-cobalt tetroxide comprises the following steps: S1. First, prepare a cobalt chloride solution and an ammonium bicarbonate solution. Specifically, weigh 16.14 g of cobalt chloride hexahydrate into a beaker, and then add 30 ml of deionized water; at the same time, weigh 11.78 g of ammonium bicarbonate into another beaker, and then add 55 ml of deionized water to obtain a cobalt chloride solution and an ammonium bicarbonate solution, respectively; take 2.3 ml of a 30% hydrogen peroxide solution, first add the hydrogen peroxide solution dropwise to the cobalt chloride solution, and then add the ammonium bicarbonate solution dropwise to the cobalt chloride solution, stirring while adding dropwise, mixing evenly, and finally stirring for 1 hour to obtain a mixed solution; S2. The mixed solution obtained in step S1 was transferred into a reactor lined with 200 ml of polytetrafluoroethylene, and the reactor was placed in a rotary oven with the temperature set at 200° C. and the holding time was 6 h. After the reaction was completed, the mixture was naturally cooled to room temperature. The obtained product was subjected to solid-liquid separation, and the precipitate was collected and washed with deionized water for 4-5 times. The precipitate was dried in a blast drying oven at 70° C. for 12 h to obtain nano-cobalt tetroxide.

[0049] The XRD pattern of the nano-cobalt tetroxide prepared in this comparative example is as follows: Figure 4 As shown, from Figure 4 As can be seen from the figure, the main component of the prepared nano-cobalt tetroxide is cobalt carbonate, containing a small amount of cobalt tetroxide. The particle size of the nano-cobalt tetroxide is 0.1~11μm, and the purity is 27.12%.

[0050] In summary, the present invention can prepare cobalt trioxide nanomaterials with higher purity and more uniform particle size by controlling the molar concentration of the cobalt salt solution, the mass concentration of the oxidant, the molar concentration of the bicarbonate solution, and the volume ratio of the cobalt salt solution, the oxidant, and the bicarbonate solution within a specific range.

[0051] It should be noted that the above embodiments all belong to the same inventive concept, and the description of each embodiment has its own focus. For any details not described in individual embodiments, reference may be made to the description in other embodiments.

[0052] The above-described embodiments merely illustrate the implementation methods of the present invention. While the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the patent. It should be noted that a person skilled in the art would be able to make various modifications and improvements without departing from the spirit of the present invention, all of which fall within the scope of protection of the present invention. Therefore, the scope of protection of the patent for this invention shall be determined by the appended claims.

Claims

1. A method for preparing nano-cobalt tetroxide, characterized in that: The steps include: S1, adding an oxidant and a bicarbonate solution to a cobalt salt solution, mixing them uniformly, to obtain a mixed solution; S2, performing a hydrothermal reaction on the mixed solution, and performing solid-liquid separation, washing, and drying on the obtained product to obtain nano-cobalt tetroxide; Wherein, in step S1, the oxidant includes a hydrogen peroxide solution.

2. The method for preparing nano-cobalt tetroxide according to claim 1, wherein: In step S1, the molar concentration of the cobalt salt solution is 2-2.5 mol / L, the mass concentration of the oxidant is 25-35%, and the molar concentration of the bicarbonate solution is 2.2-2.7 mol / L; and the volume ratio of the cobalt salt solution, the oxidant, and the bicarbonate solution is (25-35):(6-25):(50-60).

3. The method for preparing nano-cobalt tetroxide according to claim 1, wherein: In step S1, the cobalt salt solution includes at least one of a cobalt chloride solution, a cobalt sulfate solution, and a cobalt nitrate solution.

4. The method for preparing nano-cobalt tetroxide according to claim 1, wherein: In step S1, the bicarbonate solution includes at least one of an ammonium bicarbonate solution, a sodium bicarbonate solution, and a potassium bicarbonate solution.

5. The method for preparing nano-cobalt tetroxide according to claim 1, wherein: In step S1, the uniform mixing specifically includes: a mixing time of 0.5-1.5 hours.

6. The method for preparing nano-cobalt tetroxide according to claim 1, wherein: In step S2, the hydrothermal reaction specifically includes: the hydrothermal reaction temperature is 160-240° C., and the time is 3-15 hours.

7. The method for preparing nano-cobalt tetroxide according to claim 1, characterized in that: In step S2, the washing and drying specifically includes: first washing with deionized water for 3-5 times, and then drying at a constant temperature.

8. The method for preparing nano-cobalt tetroxide according to claim 7, characterized in that: The constant temperature drying specifically includes: drying at a temperature of 60-80° C. for 10-15 hours.

9. A nano-cobalt tetroxide, characterized in that: The nano-cobalt tetroxide is prepared by the preparation method described in any one of claims 1 to 8.

10. The nano-cobalt tetroxide according to claim 9, characterized in that: The particle size of the nano-cobalt tetroxide is 50-700nm.

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