Process method for efficiently preparing nano cobalt phosphide

Abstract

The invention relates to the technical field of nano material preparation, in particular to a process method for efficiently preparing nano cobalt phosphide. The process method comprises a raw material preparation and solution preparation stage, a cobalt hydroxide nano precipitate generation stage, a cobalt hydroxide precipitate collection and washing stage, a cobalt hydroxide and sodium hypophosphite pretreatment stage, a high-temperature phosphating reaction stage, a stirring and boiling phosphating stage and a reaction product collection and treatment stage. According to the technological method, efficient and batch preparation of nano cobalt phosphide is achieved through a series of fine control steps, the method has the advantages of being simple in reaction process, short in needed time, high in product purity, uniform in particle size distribution and the like, and the quality and yield of the product can be further improved by optimizing reaction conditions and controlling the reaction process.

Description

Technical Field

[0001] The invention relates to the technical field of nano material preparation, and in particular to a process for efficiently preparing nano cobalt phosphide. Background Art

[0002] Cobalt phosphide is a compound composed of cobalt and phosphorus. It has a metallic luster and usually appears as a gray or black powder. Cobalt phosphide has application potential in many fields due to its special physical and chemical properties. Cobalt phosphide is a powdery substance. It is generally stable at higher temperatures. It is relatively stable in the air, but can react with oxygen at high temperatures. It can be dissolved in acids such as hydrochloric acid and nitric acid. As an efficient catalyst, cobalt phosphide has important applications in hydrogen production, hydrogenation reactions and other fields; as an electronic material, due to its good electrical conductivity and thermal stability, cobalt phosphide can be used to manufacture semiconductor devices and battery materials; as a magnetic material, it exhibits good magnetic properties and can be used in magnetic recording materials; as a catalyst, cobalt phosphide also shows certain potential in the treatment of wastewater and exhaust gas. In recent years, cobalt phosphide has also been used as a fuel cell and water electrolysis catalyst.

[0003] There are various methods for preparing cobalt phosphide, and different methods are suitable for different application scenarios and requirements. The following are several common preparation methods: 1. Direct synthesis This is one of the most direct methods, which is to prepare cobalt phosphide by mixing cobalt powder and phosphorus powder in a certain proportion and reacting them at high temperature. For example, a mixture of cobalt powder and red phosphorus is placed in a quartz tube, heated to 700-900°C under the protection of inert gas, kept for a period of time, and then cooled to obtain cobalt phosphide.

[0004] 2. Sol-Gel Method This method is to first prepare a solution containing cobalt and phosphorus precursors, then form a sol through hydrolysis or condensation reaction, and then obtain cobalt phosphide through drying and heat treatment. This method can better control the morphology and size of the product.

[0005] 3. Vapor deposition method Cobalt phosphide thin films can be deposited on specific substrates using chemical vapor deposition (CVD) or physical vapor deposition (PVD) techniques. This usually involves introducing vapors of cobalt and phosphorus sources into a reaction chamber, where they react under appropriate temperature and pressure conditions to form cobalt phosphide.

[0006] 4. Hydrothermal / solvothermal method In a sealed container, a solution containing cobalt ions and a phosphorus source is reacted under high temperature and high pressure conditions to produce nano-scale cobalt phosphide particles. This method can better control the size and morphology of the particles.

[0007] 5. Microwave-assisted synthesis By utilizing the characteristics of microwave heating, the reaction system can be heated quickly and evenly, thereby accelerating the synthesis process of cobalt phosphide. This method is suitable for small-scale rapid synthesis.

[0008] 6. Electrochemical Deposition Cobalt phosphide can be deposited on the cathode by electrolyzing a solution containing cobalt ions and a phosphorus source. This method is particularly effective for preparing thin films or coatings.

[0009] 7. Wet Chemical Method By mixing a cobalt salt solution with a phosphorus source solution and reacting them under appropriate pH and temperature conditions, a cobalt phosphide precipitate can be prepared, which is then filtered, washed and dried to obtain the final product.

[0010] Each method has its own characteristics and scope of application, and the selection of an appropriate preparation method needs to be determined based on actual needs. For example, if large-scale production is required, the direct synthesis method may be preferred; if nanomaterials with specific morphology or size need to be prepared, the sol-gel method or hydrothermal method may be more suitable.

[0011] As a new generation of catalyst materials, cobalt phosphide can be used as battery electrodes, chemical industry, electronic devices, etc. and has a wide range of uses. At present, the specific technologies for preparing cobalt phosphide mainly include sodium hypophosphite phosphating method, microwave method, metal salt and diammonium hydrogen phosphate reaction method, phosphorus iron plus cobalt reaction method, etc. Since the above methods belong to solid-gas reactions, the PH3 produced needs to penetrate the solid phase cobalt salt to react. The phosphate salt must be used in excess or even more than 10 times, resulting in a waste of phosphate salt and cannot be mass-produced, and the output cobalt phosphide salt will not be very pure. A method for efficiently preparing cobalt phosphide is urgently needed. Summary of the invention

[0012] In order to solve some problems existing in the above-mentioned prior art, the present invention provides a process method for efficiently preparing nano cobalt phosphide, which only requires 1 times excess sodium hypophosphite for complete reaction. The method can produce nano cobalt phosphide with uniform particle size distribution and a particle size of less than 20nm. The preparation process is simple, the time required is short, and mass production can be realized.

[0013] To achieve the above-mentioned purpose, the present invention provides a process for efficiently preparing nano cobalt phosphide, the process comprising a raw material preparation and solution preparation stage, a cobalt hydroxide nano precipitate generation stage, a cobalt hydroxide precipitate collection and washing stage, a cobalt hydroxide and sodium hypophosphite pretreatment stage, a high-temperature phosphating reaction stage, a stirring and boiling phosphating stage, and a reaction product collection and treatment stage, wherein the raw material preparation and solution preparation stage comprises the following steps: Step 1: Prepare cobalt chloride (CoCl2·6H2O) as a cobalt source, dissolve a certain amount of cobalt chloride in deionized water or distilled water to prepare a cobalt chloride solution of a certain concentration; Step 2: Dissolve a certain amount of sodium hydroxide in deionized water or distilled water to prepare a sodium hydroxide solution of a certain concentration, and prepare appropriate amounts of sodium hydroxide solution and hydrogen peroxide solution for use.

[0014] Step 3: Pass hydrogen peroxide into reactor A, and start the stirring device in reactor A to ensure that the hydrogen peroxide solution is evenly distributed in the reactor.

[0015] As a further improvement of the present invention, in order to help generate cobalt hydroxide nano-precipitates with uniform particle size distribution and high purity and provide a high-quality raw material basis for the subsequent high-temperature phosphating reaction, the generation stage of the cobalt hydroxide nano-precipitates includes the following steps: Step 1: Under mechanical stirring, the cobalt chloride solution is slowly transferred to the reactor A containing hydrogen peroxide to allow the hydrogen peroxide and the cobalt chloride to fully react; Step 2: Then, sodium hydroxide solution is added dropwise to adjust the pH value of the reaction system to an appropriate range, such as a pH value of about 9 or 10; during the reaction, brown-black cobalt hydroxide (Co(OH)3) nanoprecipitates are generated.

[0016] As a further improvement of the present invention, in order to ensure the purity of the precipitate, provide reliable raw material guarantee for the subsequent high-temperature phosphating reaction, help to achieve the continuity and automation of the preparation process, and improve production efficiency, the collection and washing stage of the cobalt hydroxide precipitate includes the following steps: Step 1: After the reaction is completed, stop stirring and heating, collect the generated cobalt hydroxide precipitate through a filtering device, transport the cobalt hydroxide precipitate to a chloride ion adsorption tank, and repeatedly wash with distilled water until no chloride ions remain to ensure the purity of the precipitate; Step 2: After washing, the filtered cobalt hydroxide precipitate is transported to transition bin A for temporary storage. At the same time, storage bin A is used to store sodium hypophosphite (NaH2PO2) powder to ensure that the sodium hypophosphite is dry and easy to use.

[0017] As a further improvement of the present invention, in order to remove moisture and residual gas in the raw materials, create favorable conditions for the subsequent high-temperature phosphating reaction, and improve the efficiency and accuracy of the preparation process: the pretreatment stage of the cobalt hydroxide and sodium hypophosphite includes the following steps: Step 1: Load the cobalt hydroxide powder into a high barrel crucible through a robot or an automatic conveying device, then put the crucible containing the cobalt hydroxide powder into a tube furnace through a robot, set the heating program, heat the tube furnace to a certain temperature, and perform high-temperature pretreatment to remove moisture and residual gas in the cobalt hydroxide powder; Step 2: Take the sodium hypophosphite (NaH2PO2) powder out of the storage bin A, put it into another high barrel crucible through an automatic weighing device and a conveying device, and then put it into another container in the tube furnace through a robot; As a further improvement of the present invention, in order to efficiently prepare nano cobalt phosphide and provide an effective way for large-scale production of nano cobalt phosphide: the high-temperature phosphating reaction stage includes the following steps: Step 1: Evacuate the tube furnace to remove air and impurities from the furnace, and then heat it to a certain temperature to decompose the sodium hypophosphite to produce phosphine (PH3) gas and disodium hydrogen phosphate (Na2HPO4).

[0018] Step 2: Nitrogen (N2) is introduced as a carrier gas into a container containing sodium hypophosphite, so that the phosphine gas generated by the decomposition of the sodium hypophosphite flows out with the nitrogen and continues to be introduced into the bottom of the crucible containing cobalt hydroxide powder; the phosphine gas reacts with the cobalt hydroxide powder at high temperature to generate cobalt phosphide (CoP) and water.

[0019] As a further improvement of the present invention, in order to enhance the contact and reaction efficiency between the gas and the powder, make the reaction more complete and uniform, and improve the quality and yield of the product: the stirring and boiling phosphating stage includes the following steps: Step 1: Continuously introduce nitrogen gas to keep the cobalt hydroxide powder in a floating state. The nitrogen gas stirs and boils the cobalt hydroxide powder at the bottom of the crucible to phosphate, thereby enhancing the contact and reaction efficiency between the gas and the powder. Step 2: After the reaction is completed, stop heating and introducing nitrogen, wait for the tube furnace to cool down, and then take out the reaction product.

[0020] As a further improvement of the present invention, in order to further improve the stability and storage performance of the product and provide reliable raw material guarantee for subsequent applications: the collection and processing stage of the reaction product includes the following steps: Step 1: Collect the generated cobalt phosphide product through a filtering device and send it to a storage bin B; sieve and filter the cobalt phosphide product to remove impurities and unreacted particles; finally, send the filtered cobalt phosphide product to a vacuum dryer for vacuum drying to remove residual moisture and gas, and obtain the final nano cobalt phosphide powder product; Step 2: Collect the obtained nano cobalt phosphide powder product into a storage bin C for processing in the next step or for storage.

[0021] When the present invention works, the workflow of the present invention is as follows: 1. Raw material preparation and solution preparation High-purity cobalt chloride (CoCl2·6H2O) is used as the cobalt source. A certain amount of cobalt chloride is dissolved in deionized water or distilled water, and the cobalt chloride is ensured to be completely dissolved by accurate weighing and slow addition to form a cobalt chloride solution of a certain concentration. In this step, the concentration of the cobalt chloride solution should be accurately calculated according to the requirements of the subsequent reaction.

[0022] High-purity sodium hydroxide (NaOH) is used as the alkali source. A certain amount of sodium hydroxide is dissolved in deionized water or distilled water to form a sodium hydroxide solution of a certain concentration. Similarly, the concentration of the sodium hydroxide solution also needs to be accurately calculated according to the requirements of the subsequent reaction.

[0023] Select a high concentration of hydrogen peroxide (H2O2) solution. Place the hydrogen peroxide solution in reactor A and start the stirring device to ensure that the hydrogen peroxide solution is evenly distributed in the reactor.

[0024] 2. Formation of Cobalt Hydroxide Nanoprecipitate Under mechanical stirring, the cobalt chloride solution is slowly transferred to the reactor A containing hydrogen peroxide. In this process, hydrogen peroxide acts as an oxidant and reacts with cobalt chloride to generate an intermediate product. On the basis of the reaction between cobalt chloride and hydrogen peroxide, sodium hydroxide solution is added dropwise to adjust the pH value of the reaction system to a suitable range (such as a pH value of about 9 or 10). With the addition of sodium hydroxide solution, brown-black cobalt hydroxide (Co(OH)3) nanoprecipitates are gradually generated in the reaction system.

[0025] During the entire reaction process, parameters such as reaction temperature, stirring speed and pH value need to be strictly controlled to ensure the smooth progress of the reaction and the uniform generation of cobalt hydroxide nanoprecipitates.

[0026] 3. Collection and washing of cobalt hydroxide precipitate After the reaction is completed, stirring and heating are stopped. The generated cobalt hydroxide precipitate is collected by a filtering device. During this process, the cleanliness and integrity of the filtering device need to be ensured to avoid the introduction of impurities.

[0027] The collected cobalt hydroxide precipitate is transported to the chloride ion adsorption tank and repeatedly washed with distilled water until no chloride ions remain. The purpose of this step is to remove chloride ions and other soluble impurities in the precipitate to ensure the purity of the precipitate.

[0028] 4. Pretreatment of cobalt hydroxide and sodium hypophosphite After washing is completed, the cobalt hydroxide precipitate obtained by filtration is transported to the transition bin A for temporary storage. In the transition bin A, the cobalt hydroxide precipitate can be further dried and impurity-removed.

[0029] Storage silo A is used to store sodium hypophosphite (NaH2PO2) powder. Before use, it is necessary to ensure that the sodium hypophosphite is dry and easy to access. The purity of sodium hypophosphite can be improved through proper drying and impurity removal.

[0030] 5. High temperature phosphating reaction The cobalt hydroxide powder is loaded into a high barrel crucible by a manipulator or an automatic conveying device. Then, the high barrel crucible containing the cobalt hydroxide powder is placed into a tube furnace by a manipulator. Set the heating program and heat the tube furnace to a certain temperature (such as 320°C) for high temperature pretreatment. The purpose of this step is to remove moisture and residual gas in the cobalt hydroxide powder to prepare for the subsequent phosphating reaction.

[0031] The sodium hypophosphite powder is taken out from the storage bin A and loaded into another high barrel crucible through an automatic weighing device and a conveying device. Then it is put into another container in the tube furnace by a robot. Next, the tube furnace is evacuated to a vacuum state to remove the air and impurities in the furnace. Then it is heated to a certain temperature (such as 320°C) to decompose the sodium hypophosphite to produce phosphine (PH3) gas and disodium hydrogen phosphate (Na2HPO4).

[0032] Nitrogen (N2) is introduced as a carrier gas into a container containing sodium hypophosphite, so that the phosphine gas generated by the decomposition of sodium hypophosphite flows out with the nitrogen and continues to flow into the bottom of the crucible containing cobalt hydroxide powder. The phosphine gas reacts with the cobalt hydroxide powder at high temperature to generate cobalt phosphide (CoP) and water.

[0033] 6. Stirring and boiling phosphating Continuously introduce nitrogen to keep the cobalt hydroxide powder in a floating state. Nitrogen not only acts as a carrier gas to carry phosphine gas into the reaction system, but also plays a role in stirring and boiling phosphating. The flow of nitrogen can enhance the contact between gas and powder and the reaction efficiency, making the reaction more complete and uniform.

[0034] 7. Collection and treatment of reaction products After the reaction is completed, stop heating and nitrogen. After the tubular furnace is cooled, take out the reaction product. Collect the generated cobalt phosphide product through a filtering device and send it to storage bin B. The cobalt phosphide product is screened and filtered to remove impurities and unreacted particles. The purpose of this step is to further improve the purity and quality of the product.

[0035] The filtered cobalt phosphide product is sent to a vacuum dryer for vacuum drying. Through vacuum drying, residual moisture and gas can be removed to obtain the final nano cobalt phosphide powder product.

[0036] 8. Collection and storage of products The vacuum-dried nano cobalt phosphide powder product is collected in the storage bin C. In this step, the cleanliness and sealing of the storage bin C need to be ensured to avoid contamination and loss of the product. The collected nano cobalt phosphide powder product is properly stored for subsequent processing or use. During storage, the product needs to be kept dry and moisture-proof to avoid changes in product quality.

[0037] The beneficial effects of the present invention are: Efficient preparation and particle size control: The present invention achieves efficient preparation of cobalt hydroxide nanoprecipitates by finely controlling chemical reaction conditions, such as temperature, pH value and reaction time.

[0038] In the further phosphating reaction, the phosphine gas is fully contacted with the cobalt hydroxide powder through the carrying and stirring effect of nitrogen, and the reaction is thorough, thereby obtaining nano cobalt phosphide powder with uniform particle size distribution and a particle size of less than 20 nm.

[0039] Uniform particle size: The nanometer cobalt phosphide powder prepared by the present invention has uniform particle size distribution and a particle size of less than 20 nm. This is due to the precise adjustment of the pH value of the reaction system in step 4 and the stirring effect of nitrogen in step 10, so that the generated cobalt hydroxide precipitate and the subsequent cobalt phosphide product have uniform particle sizes.

[0040] Reduced raw material waste: Compared with the prior art, the present invention significantly reduces the amount of sodium hypophosphite used. By optimizing the reaction conditions and steps, only one-fold excess of sodium hypophosphite is required for complete reaction, which greatly reduces the cost of raw materials and reduces waste emissions.

[0041] Process simplification and mass production: The preparation process of the present invention is relatively simple, with clear and definite steps, easy to operate and control. Through the application of mechanized and automated equipment, such as manipulators, automatic weighing devices and conveying devices, the whole process from raw material preparation to product collection is automated, which greatly improves production efficiency and is suitable for mass production.

[0042] High product quality: The purity and quality of the final product are ensured through fine filtering, washing and drying steps. The obtained nano cobalt phosphide powder has good dispersibility and stability and is suitable for a variety of application scenarios. BRIEF DESCRIPTION OF THE DRAWINGS

[0043] In order to facilitate the understanding of those skilled in the art, the present invention is further described below with reference to the accompanying drawings: Figure 1 This is a schematic flow chart of the furnace of the horizontal tube furnace of the boiling phosphating equipment used in the present invention, corresponding to all embodiments.

[0044] Figure 2 This is the SEM spectrum of the CoP sample obtained in the present invention, corresponding to Example 4.

[0045] Figure 3 This is the XRD spectrum of the CoP sample obtained in the present invention, corresponding to Example 4.

[0046] Figure 4 The present invention is a flow chart of the raw material preparation and solution preparation stages in the process method of the present invention.

[0047] Figure 5 The present invention is a flow chart of the generation stage of cobalt hydroxide nano-precipitates and the collection and washing stage of cobalt hydroxide precipitates in the process method of the present invention.

[0048] Figure 6 The present invention is a flow chart of the pretreatment stage of cobalt hydroxide and sodium hypophosphite, the high-temperature phosphating reaction stage, the stirring and boiling phosphating stage, and the collection and treatment stage of the reaction products in the process method of the present invention. DETAILED DESCRIPTION

[0049] In order to enable those skilled in the art to better understand the technical solution in this application, Figure 1-6 The present invention is further described. The following examples are only used to more clearly illustrate the technical solution of the present invention, and are not intended to limit the protection scope of the present invention.

[0050] like Figure 1-6 A process for efficiently preparing nano-cobalt phosphide is shown, the process comprising a raw material preparation and solution preparation stage, a cobalt hydroxide nano-precipitate generation stage, a cobalt hydroxide precipitate collection and washing stage, a cobalt hydroxide and sodium hypophosphite pretreatment stage, a high-temperature phosphating reaction stage, a stirring and boiling phosphating stage, and a reaction product collection and treatment stage, wherein the raw material preparation and solution preparation stage comprises the following steps: Step 1: Prepare cobalt chloride (CoCl2·6H2O) as a cobalt source, dissolve a certain amount of cobalt chloride in deionized water or distilled water to prepare a cobalt chloride solution of a certain concentration; Step 2: Dissolve a certain amount of sodium hydroxide in deionized water or distilled water to prepare a sodium hydroxide solution of a certain concentration, and prepare appropriate amounts of sodium hydroxide solution and hydrogen peroxide solution for use.

[0051] Step 3: Pass hydrogen peroxide into reactor A, and start the stirring device in reactor A to ensure that the hydrogen peroxide solution is evenly distributed in the reactor.

[0052] The generation stage of the cobalt hydroxide nano-precipitate comprises the following steps: Step 1: Under mechanical stirring, the cobalt chloride solution is slowly transferred to the reactor A containing hydrogen peroxide to allow the hydrogen peroxide and the cobalt chloride to fully react; Step 2: Then, sodium hydroxide solution is added dropwise to adjust the pH value of the reaction system to an appropriate range, such as a pH value of about 9 or 10; during the reaction, brown-black cobalt hydroxide (Co(OH)3) nanoprecipitates are generated.

[0053] The collection and washing stage of the cobalt hydroxide precipitate comprises the following steps: Step 1: After the reaction is completed, stop stirring and heating, collect the generated cobalt hydroxide precipitate through a filtering device, transport the cobalt hydroxide precipitate to a chloride ion adsorption tank, and repeatedly wash with distilled water until no chloride ions remain to ensure the purity of the precipitate; Step 2: After washing, the filtered cobalt hydroxide precipitate is transported to transition bin A for temporary storage. At the same time, storage bin A is used to store sodium hypophosphite (NaH2PO2) powder to ensure that the sodium hypophosphite is dry and easy to use.

[0054] The pretreatment stage of cobalt hydroxide and sodium hypophosphite comprises the following steps: Step 1: Load the cobalt hydroxide powder into a high barrel crucible through a robot or an automatic conveying device, then put the crucible containing the cobalt hydroxide powder into a tube furnace through a robot, set the heating program, heat the tube furnace to a certain temperature, and perform high-temperature pretreatment to remove moisture and residual gas in the cobalt hydroxide powder; Step 2: Take the sodium hypophosphite (NaH2PO2) powder out of the storage bin A, load it into another tall barrel crucible through an automatic weighing device and a conveying device, and then put it into another container in the tube furnace through a robot.

[0055] The high temperature phosphating reaction stage comprises the following steps: Step 1: Evacuate the tube furnace to remove air and impurities from the furnace, and then heat it to a certain temperature to decompose the sodium hypophosphite to produce phosphine (PH3) gas and disodium hydrogen phosphate (Na2HPO4).

[0056] Step 2: Nitrogen (N2) is introduced as a carrier gas into a container containing sodium hypophosphite, so that the phosphine gas generated by the decomposition of the sodium hypophosphite flows out with the nitrogen and continues to be introduced into the bottom of the crucible containing cobalt hydroxide powder; the phosphine gas reacts with the cobalt hydroxide powder at high temperature to generate cobalt phosphide (CoP) and water.

[0057] The stirring and boiling phosphating stage comprises the following steps: Step 1: Continuously introduce nitrogen gas to keep the cobalt hydroxide powder in a floating state. The nitrogen gas stirs and boils the cobalt hydroxide powder at the bottom of the crucible to phosphate, thereby enhancing the contact and reaction efficiency between the gas and the powder. Step 2: After the reaction is completed, stop heating and introducing nitrogen, wait for the tube furnace to cool down, and then take out the reaction product.

[0058] The collection and processing stage of the reaction products comprises the following steps: Step 1: Collect the generated cobalt phosphide product through a filtering device and send it to a storage bin B; sieve and filter the cobalt phosphide product to remove impurities and unreacted particles; finally, send the filtered cobalt phosphide product to a vacuum dryer for vacuum drying to remove residual moisture and gas, and obtain the final nano cobalt phosphide powder product; Step 2: Collect the obtained nano cobalt phosphide powder product into a storage bin C for processing in the next step or for storage.

[0059] The workflow of the present invention is as follows: 1. Raw material preparation and solution preparation High-purity cobalt chloride (CoCl2·6H2O) is used as the cobalt source. A certain amount of cobalt chloride is dissolved in deionized water or distilled water, and the cobalt chloride is ensured to be completely dissolved by accurate weighing and slow addition to form a cobalt chloride solution of a certain concentration. In this step, the concentration of the cobalt chloride solution should be accurately calculated according to the requirements of the subsequent reaction.

[0060] High-purity sodium hydroxide (NaOH) is used as the alkali source. A certain amount of sodium hydroxide is dissolved in deionized water or distilled water to form a sodium hydroxide solution of a certain concentration. Similarly, the concentration of the sodium hydroxide solution also needs to be accurately calculated according to the requirements of the subsequent reaction.

[0061] Select a high concentration of hydrogen peroxide (H2O2) solution. Place the hydrogen peroxide solution in reactor A and start the stirring device to ensure that the hydrogen peroxide solution is evenly distributed in the reactor.

[0062] 2. Formation of Cobalt Hydroxide Nanoprecipitate Under mechanical stirring, the cobalt chloride solution is slowly transferred to the reactor A containing hydrogen peroxide. In this process, hydrogen peroxide acts as an oxidant and reacts with cobalt chloride to generate an intermediate product. On the basis of the reaction between cobalt chloride and hydrogen peroxide, sodium hydroxide solution is added dropwise to adjust the pH value of the reaction system to a suitable range (such as a pH value of about 9 or 10). With the addition of sodium hydroxide solution, brown-black cobalt hydroxide (Co(OH)3) nanoprecipitates are gradually generated in the reaction system.

[0063] During the entire reaction process, parameters such as reaction temperature, stirring speed and pH value need to be strictly controlled to ensure the smooth progress of the reaction and the uniform generation of cobalt hydroxide nanoprecipitates.

[0064] 3. Collection and washing of cobalt hydroxide precipitate After the reaction is completed, stirring and heating are stopped. The generated cobalt hydroxide precipitate is collected by a filtering device. During this process, the cleanliness and integrity of the filtering device need to be ensured to avoid the introduction of impurities.

[0065] The collected cobalt hydroxide precipitate is transported to the chloride ion adsorption tank and repeatedly washed with distilled water until no chloride ions remain. The purpose of this step is to remove chloride ions and other soluble impurities in the precipitate to ensure the purity of the precipitate.

[0066] 4. Pretreatment of cobalt hydroxide and sodium hypophosphite After washing is completed, the cobalt hydroxide precipitate obtained by filtration is transported to the transition bin A for temporary storage. In the transition bin A, the cobalt hydroxide precipitate can be further dried and impurity-removed.

[0067] Storage silo A is used to store sodium hypophosphite (NaH2PO2) powder. Before use, it is necessary to ensure that the sodium hypophosphite is dry and easy to access. The purity of sodium hypophosphite can be improved through proper drying and impurity removal.

[0068] 5. High temperature phosphating reaction The cobalt hydroxide powder is loaded into a high barrel crucible by a manipulator or an automatic conveying device. Then, the high barrel crucible containing the cobalt hydroxide powder is placed into a tube furnace by a manipulator. Set the heating program and heat the tube furnace to a certain temperature (such as 320°C) for high temperature pretreatment. The purpose of this step is to remove moisture and residual gas in the cobalt hydroxide powder to prepare for the subsequent phosphating reaction.

[0069] The sodium hypophosphite powder is taken out from the storage bin A and loaded into another high barrel crucible through an automatic weighing device and a conveying device. Then it is put into another container in the tube furnace by a robot. Next, the tube furnace is evacuated to a vacuum state to remove the air and impurities in the furnace. Then it is heated to a certain temperature (such as 320°C) to decompose the sodium hypophosphite to produce phosphine (PH3) gas and disodium hydrogen phosphate (Na2HPO4).

[0070] Nitrogen (N2) is introduced as a carrier gas into a container containing sodium hypophosphite, so that the phosphine gas generated by the decomposition of sodium hypophosphite flows out with the nitrogen and continues to flow into the bottom of the crucible containing cobalt hydroxide powder. The phosphine gas reacts with the cobalt hydroxide powder at high temperature to generate cobalt phosphide (CoP) and water.

[0071] 6. Stirring and boiling phosphating Continuously introduce nitrogen to keep the cobalt hydroxide powder in a floating state. Nitrogen not only acts as a carrier gas to carry phosphine gas into the reaction system, but also plays a role in stirring and boiling phosphating. The flow of nitrogen can enhance the contact between gas and powder and the reaction efficiency, making the reaction more complete and uniform.

[0072] 7. Collection and treatment of reaction products After the reaction is completed, stop heating and nitrogen. After the tubular furnace is cooled, take out the reaction product. Collect the generated cobalt phosphide product through a filtering device and send it to storage bin B. The cobalt phosphide product is screened and filtered to remove impurities and unreacted particles. The purpose of this step is to further improve the purity and quality of the product.

[0073] The filtered cobalt phosphide product is sent to a vacuum dryer for vacuum drying. Through vacuum drying, residual moisture and gas can be removed to obtain the final nano cobalt phosphide powder product.

[0074] 8. Collection and storage of products The vacuum-dried nano cobalt phosphide powder product is collected in a storage bin C. In this step, it is necessary to ensure the cleanliness and sealing of the storage bin C to avoid contamination and loss of the product. The collected nano cobalt phosphide powder product is properly stored for subsequent processing or use.

[0075] The present invention is further described below with reference to examples. Example

[0076] An efficient method for preparing cobalt phosphide is achieved by the following process: Dissolve 10g CoCl2·6H2O in 150mL water. Under mechanical stirring, slowly add 10mL of 30% H2O2 solution. Continue stirring and add 5% NaOH solution dropwise until the pH value is about 9. Collect the generated precipitate by filtration and wash it with distilled water until there is no chloride ion. Place the filtered precipitate in an autoclave, and place the autoclave in a 150℃ constant temperature drying oven for 6h. Filter, wash, and dry. Put the obtained nano Co(OH)3 powder into a high barrel crucible (set as A) and put it into a tube furnace. Put 100g sodium hypophosphite NaH2PO2 powder (9 times excess) into another container in the tube furnace (set as B). Evacuate the tube furnace, heat to 320℃ and keep warm for 2h, pass N2 into container B, so that it carries the generated PH3 gas and continues to pass into the bottom of crucible A, so that the gas can blow the Co(OH)3 powder, making it in a floating state, playing a stirring role, which is conducive to gas mass transfer and makes the reaction thorough. The chemical reaction equation is 2NaH2PO2=Na2HPO4+PH3↑, PH3+Co(OH)3=CoP+3H2O. Filter, wash, and vacuum dry to obtain the cobalt phosphide CoP product. 3.81g CoP nano powder is obtained. Example

[0077] An efficient method for preparing cobalt phosphide is achieved by the following process: Dissolve 10g CoCl2·6H2O in 150mL water. Under mechanical stirring, slowly add 10mL of 30% H2O2 solution. Continue stirring and add 5% NaOH solution dropwise until the pH value is about 9. Collect the generated precipitate by filtration and wash it with distilled water until there is no chloride ion. Place the filtered precipitate in an autoclave, and place the autoclave in a 150℃ constant temperature drying oven for 6h. Filter, wash, and dry. Put the obtained nano Co(OH)3 powder into a high barrel crucible (set as A) and put it into a tube furnace. Put 50g sodium hypophosphite NaH2PO2 powder (4 times excess) into another container in the tube furnace (set as B). Evacuate the tube furnace, heat to 320℃ and keep warm for 1.5h, pass N2 into container B, so that it carries the generated PH3 gas and continues to pass into the bottom of crucible A, so that the gas can blow the Co(OH)3 powder, making it in a floating state, playing a stirring role, which is conducive to gas mass transfer and makes the reaction thorough. The chemical reaction equation is 2NaH2PO2=Na2HPO4+PH3↑, PH3+Co(OH)3=CoP+3H2O. Filter, wash, and vacuum dry to obtain the cobalt phosphide CoP product. 3.81g CoP nano powder is obtained. Example

[0078] An efficient method for preparing cobalt phosphide is achieved by the following process: Dissolve 10g CoCl2·6H2O in 150mL water. Under mechanical stirring, slowly add 10mL of 30% H2O2 solution. Continue stirring and add 5% NaOH solution dropwise until the pH value is about 10. Collect the generated precipitate by filtration and wash it with distilled water until there is no chloride ion. Place the filtered precipitate in an autoclave, and place the autoclave in a 150℃ constant temperature drying oven for 6h. Filter, wash, and dry. Put the obtained nano Co(OH)3 powder into a high barrel crucible (set as A) and put it into a tube furnace. Put 30g sodium hypophosphite NaH2PO2 powder (2 times excess) into another container in the tube furnace (set as B). Evacuate the tube furnace, heat to 320℃ and keep warm for 1h, pass N2 into container B, so that it carries the generated PH3 gas and continues to pass into the bottom of crucible A, so that the gas can blow the Co(OH)3 powder, making it in a floating state, playing a stirring role, which is conducive to gas mass transfer and makes the reaction thorough. The chemical reaction equation is 2NaH2PO2=Na2HPO4+PH3↑, PH3+Co(OH)3=CoP+3H2O. Filter, wash, and vacuum dry to obtain the cobalt phosphide CoP product. 3.82g of CoP nanopowder is obtained. Example

[0079] An efficient method for preparing cobalt phosphide is achieved by the following process: Dissolve 10g CoCl2·6H2O in 150mL water. Under mechanical stirring, slowly add 10mL of 30% H2O2 solution. Continue stirring and add 5% NaOH solution dropwise until the pH value is about 10. Collect the generated precipitate by filtration and wash it with distilled water until there is no chloride ion. Place the filtered precipitate in an autoclave, and place the autoclave in a 150℃ constant temperature drying oven for 6h. Filter, wash, and dry. Put the obtained nano Co(OH)3 powder into a high barrel crucible (set as A) and put it into a tube furnace. Put 20g sodium hypophosphite NaH2PO2 powder (1 times excess) into another container in the tube furnace (set as B). Evacuate the tube furnace, heat to 320℃ and keep warm for 0.5h, pass N2 into container B, so that it carries the generated PH3 gas and continues to pass into the bottom of crucible A, so that the gas can blow the Co(OH)3 powder, making it in a floating state, playing a stirring role, which is conducive to gas mass transfer and makes the reaction thorough. The chemical reaction equation is 2NaH2PO2=Na2HPO4+PH3↑, PH3+Co(OH)3=CoP+3H2O. Filter, wash, and vacuum dry to obtain the cobalt phosphide CoP product. 3.82g of CoP nanopowder is obtained.

[0080] The present invention is not limited to the above-mentioned embodiments. On the basis of the technical solution disclosed in the present invention, technicians in this field can make some substitutions and deformations to some technical features therein according to the disclosed technical content without creative labor, and these substitutions and deformations are all within the protection scope of the present invention.

Claims

1. A process for efficiently preparing nano-cobalt phosphide, characterized in that: The process method comprises a raw material preparation and solution preparation stage, a cobalt hydroxide nano-precipitate generation stage, a cobalt hydroxide precipitate collection and washing stage, a cobalt hydroxide and sodium hypophosphite pretreatment stage, a high-temperature phosphating reaction stage, a stirring and boiling phosphating stage, and a reaction product collection and treatment stage. The raw material preparation and solution preparation stage comprises the following steps: Step 1: Prepare cobalt chloride (CoCl2·6H2O) as a cobalt source, dissolve a certain amount of cobalt chloride in deionized water or distilled water to prepare a cobalt chloride solution of a certain concentration; Step 2: dissolve a certain amount of sodium hydroxide in deionized water or distilled water to prepare a sodium hydroxide solution of a certain concentration, and prepare appropriate amounts of sodium hydroxide solution and hydrogen peroxide solution for standby use; Step 3: Pass hydrogen peroxide into reactor A, and start the stirring device in reactor A to ensure that the hydrogen peroxide solution is evenly distributed in the reactor.

2. The process for efficiently preparing nano-cobalt phosphide according to claim 1, characterized in that: The generation stage of the cobalt hydroxide nano-precipitate comprises the following steps: Step 1: Under mechanical stirring, the cobalt chloride solution is slowly transferred to the reactor A containing hydrogen peroxide to allow the hydrogen peroxide and the cobalt chloride to fully react; Step 2: Then, sodium hydroxide solution is added dropwise to adjust the pH value of the reaction system to an appropriate range, such as a pH value of about 9 or 10; during the reaction, brown-black cobalt hydroxide (Co(OH)3) nanoprecipitates are generated.

3. The process for efficiently preparing nano-cobalt phosphide according to claim 1, characterized in that: The collection and washing stage of the cobalt hydroxide precipitate comprises the following steps: Step 1: After the reaction is completed, stop stirring and heating, collect the generated cobalt hydroxide precipitate through a filtering device, transport the cobalt hydroxide precipitate to a chloride ion adsorption tank, and repeatedly wash with distilled water until no chloride ions remain to ensure the purity of the precipitate; Step 2: After washing, the filtered cobalt hydroxide precipitate is transported to transition bin A for temporary storage. At the same time, storage bin A is used to store sodium hypophosphite (NaH2PO2) powder to ensure that the sodium hypophosphite is dry and easy to use.

4. The process for efficiently preparing nano-cobalt phosphide according to claim 1, characterized in that: The pretreatment stage of cobalt hydroxide and sodium hypophosphite comprises the following steps: Step 1: Load the cobalt hydroxide powder into a high barrel crucible through a robot or an automatic conveying device, then put the crucible containing the cobalt hydroxide powder into a tube furnace through a robot, set the heating program, heat the tube furnace to a certain temperature, and perform high-temperature pretreatment to remove moisture and residual gas in the cobalt hydroxide powder; Step 2: Take the sodium hypophosphite (NaH2PO2) powder out of the storage bin A, load it into another tall barrel crucible through an automatic weighing device and a conveying device, and then put it into another container in the tube furnace through a robot.

5. The process for efficiently preparing nano-cobalt phosphide according to claim 1, characterized in that: The high temperature phosphating reaction stage comprises the following steps: Step 1: The tube furnace is evacuated to a vacuum state to remove air and impurities in the furnace, and then heated to a certain temperature to decompose the sodium hypophosphite to produce phosphine (PH3) gas and disodium hydrogen phosphate (Na2HPO4); Step 2: Nitrogen (N2) is introduced as a carrier gas into a container containing sodium hypophosphite, so that the phosphine gas generated by the decomposition of the sodium hypophosphite flows out with the nitrogen and continues to be introduced into the bottom of the crucible containing cobalt hydroxide powder; the phosphine gas reacts with the cobalt hydroxide powder at high temperature to generate cobalt phosphide (CoP) and water.

6. The process for efficiently preparing nano-cobalt phosphide according to claim 1, characterized in that: The stirring and boiling phosphating stage comprises the following steps: Step 1: Continuously introduce nitrogen gas to keep the cobalt hydroxide powder in a floating state. The nitrogen gas stirs and boils the cobalt hydroxide powder at the bottom of the crucible to phosphate, thereby enhancing the contact and reaction efficiency between the gas and the powder. Step 2: After the reaction is completed, stop heating and introducing nitrogen, wait for the tube furnace to cool down, and then take out the reaction product.

7. The process for efficiently preparing nano-cobalt phosphide according to claim 1, characterized in that: The collection and processing stage of the reaction products comprises the following steps: Step 1: Collect the generated cobalt phosphide product through a filtering device and send it to a storage bin B; sieve and filter the cobalt phosphide product to remove impurities and unreacted particles; finally, send the filtered cobalt phosphide product to a vacuum dryer for vacuum drying to remove residual moisture and gas, and obtain the final nano cobalt phosphide powder product; Step 2: Collect the obtained nano cobalt phosphide powder product into a storage bin C for processing in the next step or for storage.

Images