A process for preparing nano-cobalt phosphide

Abstract

The present invention relates to the technical field of nanomaterial preparation, and 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 processing stage. The process method of the present invention realizes efficient and batch preparation of nano-cobalt phosphide through a series of finely controlled steps. The method has the advantages of a simple reaction process, a short required time, high product purity, and uniform particle size distribution. By optimizing reaction conditions and controlling the reaction process, the quality and yield of the product can be further improved.

Description

Technical Field

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

[0002] Cobalt phosphide is a compound composed of the elements cobalt and phosphorus. It has a metallic luster and usually appears as a gray or black powder. Due to its unique physical and chemical properties, cobalt phosphide has application potential in many fields. Cobalt phosphide is a powdery substance. It is generally stable at higher temperatures. It is relatively stable in air but can react with oxygen at high temperatures. It is soluble in acids such as hydrochloric acid and nitric acid. As a highly efficient catalyst, cobalt phosphide has important applications in hydrogen production and hydrogenation reactions. 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 gases. In recent years, cobalt phosphide has also been used as a catalyst in fuel cells and water electrolysis.

[0003] There are many methods for preparing cobalt phosphide, and different methods are suitable for different application scenarios and requirements. The following are some common preparation methods:

[0004] 1. Direct Synthesis

[0005] This is one of the most direct methods. Cobalt phosphide is prepared by mixing cobalt powder and phosphorus powder in a certain ratio and reacting them at high temperature. For example, the cobalt powder and red phosphorus mixture is placed in a quartz tube, heated to 700-900°C under an inert gas atmosphere, held for a period of time, and then cooled to obtain cobalt phosphide.

[0006] 2. Sol-Gel Method

[0007] This method involves first preparing a solution containing cobalt and phosphorus precursors, then forming a sol through hydrolysis or condensation, and then drying and heat treating it to obtain cobalt phosphide. This method allows for better control of the product's morphology and size.

[0008] 3. Vapor deposition method

[0009] Cobalt phosphide thin films can be deposited on specific substrates using chemical vapor deposition (CVD) or physical vapor deposition (PVD) techniques. This typically 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.

[0010] 4. Hydrothermal / solvothermal method

[0011] In a sealed container, a solution containing cobalt ions and a phosphorus source reacts under high temperature and high pressure to produce nanoscale cobalt phosphide particles. This method allows for better control of particle size and morphology.

[0012] 5. Microwave-assisted synthesis

[0013] 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.

[0014] 6. Electrochemical Deposition

[0015] 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.

[0016] 7. Wet Chemical Method

[0017] 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. The final product is then obtained through filtration, washing, and drying.

[0018] Each method has its own characteristics and scope of application, and choosing the appropriate preparation method should be determined based on actual needs. For example, if large-scale production is required, direct synthesis may be preferred; if nanomaterials with specific morphologies or sizes need to be prepared, sol-gel or hydrothermal methods may be more suitable.

[0019] Cobalt phosphide, as a new generation catalyst material, can be used as battery electrodes, chemical industry, electronic devices, etc. and has a wide range of applications. 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. Because the above methods are solid-gas reactions, the generated PH3 needs to penetrate the solid phase cobalt salt to react. The phosphate salt must be used in excess, even up to 10 times, resulting in waste of phosphate salt and cannot be produced in large quantities. The cobalt phosphide salt produced will not be very pure. There is an urgent need for a method for efficiently preparing cobalt phosphide. Summary of the Invention

[0020] To address some of the problems existing in the above-mentioned prior art, the present invention provides a process for efficiently preparing nano-cobalt phosphide. The process requires only a 1-fold excess of sodium hypophosphite for complete reaction. The process can produce nano-cobalt phosphide with a uniform particle size distribution and a particle size of less than 20 nm. The preparation process is simple, the time required is short, and mass production can be achieved.

[0021] To achieve the above-mentioned object, 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. The raw material preparation and solution preparation stage comprises the following steps:

[0022] 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.

[0023] 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.

[0024] Step 3: Pour 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.

[0025] 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:

[0026] 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 cobalt chloride to fully react;

[0027] 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.

[0028] 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:

[0029] Step 1: After the reaction is completed, stirring and heating are stopped, and the generated cobalt hydroxide precipitate is collected by a filtration device, and the cobalt hydroxide precipitate is transported to a chloride ion adsorption tank, and repeatedly washed with distilled water until no chloride ions remain, to ensure the purity of the precipitate;

[0030] Step 2: After washing, the filtered cobalt hydroxide precipitate is transported to the transition bin A for temporary storage. At the same time, the storage bin A is used to store sodium hypophosphite (NaH2PO2) powder to ensure that the sodium hypophosphite is dry and easy to use.

[0031] 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:

[0032] Step 1: Load the cobalt hydroxide powder into a tall crucible via a robot or automatic conveyor. Then, place the crucible containing the cobalt hydroxide powder into a tube furnace via a robot. Set the heating program and heat the tube furnace to a certain temperature for high-temperature pretreatment to remove moisture and residual gas from the cobalt hydroxide powder.

[0033] Step 2: Take the sodium hypophosphite (NaH2PO2) powder out of storage bin A, put 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;

[0034] As a further improvement of the present invention, in order to efficiently prepare nano-cobalt phosphide and provide an effective approach for large-scale production of nano-cobalt phosphide: the high-temperature phosphating reaction stage includes the following steps:

[0035] Step 1: Evacuate the tubular furnace to remove air and impurities from the furnace, then heat it to a certain temperature to decompose the sodium hypophosphite to produce phosphine (PH3) gas and disodium hydrogen phosphate (Na2HPO4).

[0036] Step 2: Nitrogen (N2) is introduced as a carrier gas into a container containing sodium hypophosphite, causing the phosphine gas produced by the decomposition of the sodium hypophosphite to flow out along with the nitrogen and continue to flow into the bottom of a crucible containing cobalt hydroxide powder; the phosphine gas reacts with the cobalt hydroxide powder at high temperature to produce cobalt phosphide (CoP) and water.

[0037] 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:

[0038] 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 between the gas and the powder and the reaction efficiency.

[0039] 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.

[0040] 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:

[0041] Step 1: The generated cobalt phosphide product is collected through a filtration device and sent to a storage bin B; the cobalt phosphide product is screened and filtered to remove impurities and unreacted particles; and finally, the filtered cobalt phosphide product is sent to a vacuum dryer for vacuum drying to remove residual moisture and gas, thereby obtaining a final nano-cobalt phosphide powder product.

[0042] Step 2: Collect the obtained nano-cobalt phosphide powder product into the storage bin C for processing in the next step or storage for future use.

[0043] When the present invention works, the workflow of the present invention is as follows:

[0044] 1. Raw material preparation and solution preparation

[0045] Use high-purity cobalt chloride (CoCl2·6H2O) as the cobalt source. Dissolve a certain amount of cobalt chloride in deionized or distilled water. Accurately weigh and slowly add the solution to ensure complete dissolution, forming a cobalt chloride solution of a certain concentration. The concentration of the cobalt chloride solution should be precisely calculated based on the requirements of subsequent reactions.

[0046] High-purity sodium hydroxide (NaOH) is used as the alkaline source. A certain amount of sodium hydroxide is dissolved in deionized or distilled water to form a sodium hydroxide solution of a certain concentration. Similarly, the concentration of the sodium hydroxide solution must be precisely calculated based on the requirements of the subsequent reaction.

[0047] Use a high-concentration 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.

[0048] 2. Formation of Cobalt Hydroxide Nanoprecipitates

[0049] Under mechanical stirring, the cobalt chloride solution is slowly transferred to Reactor A containing hydrogen peroxide. During this process, the hydrogen peroxide acts as an oxidant, reacting with the cobalt chloride to form an intermediate product. As the cobalt chloride and hydrogen peroxide react, sodium hydroxide solution is added dropwise to adjust the pH of the reaction system to an appropriate range (e.g., approximately 9 or 10). With the addition of sodium hydroxide solution, a brown-black cobalt hydroxide (Co(OH)3) nanoprecipitate gradually forms in the reaction system.

[0050] 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 formation of cobalt hydroxide nanoprecipitates.

[0051] 3. Collection and washing of cobalt hydroxide precipitate

[0052] After the reaction is complete, stirring and heating are stopped. The generated cobalt hydroxide precipitate is collected by filtration. During this process, the cleanliness and integrity of the filtration device must be ensured to avoid the introduction of impurities.

[0053] The collected cobalt hydroxide precipitate is transferred to a chloride ion adsorption tank and repeatedly washed with distilled water until no chloride ions remain. This step is to remove chloride ions and other soluble impurities from the precipitate, ensuring its purity.

[0054] 4. Pretreatment of cobalt hydroxide and sodium hypophosphite

[0055] After washing is completed, the cobalt hydroxide precipitate obtained by filtration is transported to the transition chamber A for temporary storage. In the transition chamber A, the cobalt hydroxide precipitate can be further dried and impurity-removed.

[0056] Storage silo A is used to store sodium hypophosphite (NaH2PO2) powder. Before use, ensure that the sodium hypophosphite is dry and easily accessible. The purity of the sodium hypophosphite can be improved through proper drying and impurity removal.

[0057] 5. High temperature phosphating reaction

[0058] Cobalt hydroxide powder is loaded into a tall crucible using a robot or automated conveyor. The crucible containing the cobalt hydroxide powder is then placed into a tube furnace using a robot. After setting the heating program, the tube furnace is heated to a specific temperature (e.g., 320°C) for high-temperature pretreatment. This step removes moisture and residual gases from the cobalt hydroxide powder, preparing it for the subsequent phosphating reaction.

[0059] Sodium hypophosphite powder is removed from storage silo A and loaded into another tall crucible via an automatic weighing device and conveyor. A robotic arm then places it into another container in a tube furnace. The tube furnace is then evacuated to a vacuum state to remove air and impurities. The sodium hypophosphite is then heated to a certain temperature (e.g., 320°C) to decompose, producing phosphine (PH3) gas and disodium hydrogen phosphate (Na2HPO4).

[0060] Nitrogen (N2) is introduced as a carrier gas into a container containing sodium hypophosphite. Phosphine gas, produced by the decomposition of the sodium hypophosphite, flows out along with the nitrogen and continues to flow into the bottom of a crucible containing cobalt hydroxide powder. The phosphine gas reacts with the cobalt hydroxide powder at high temperatures to produce cobalt phosphide (CoP) and water.

[0061] 6. Stirring and boiling phosphating

[0062] Continuously flowing nitrogen gas keeps the cobalt hydroxide powder in a floating state. Nitrogen not only acts as a carrier gas to carry the phosphine gas into the reaction system but also provides stirring and boiling phosphating. The flow of nitrogen enhances gas-powder contact and reaction efficiency, making the reaction more complete and uniform.

[0063] 7. Collection and treatment of reaction products

[0064] After the reaction is complete, heating and nitrogen flow are stopped. After the tubular furnace cools, the reaction product is removed. The resulting cobalt phosphide product is collected using a filter and transferred to storage bin B. The cobalt phosphide product is screened and filtered to remove impurities and unreacted particles. This step further improves the purity and quality of the product.

[0065] 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.

[0066] 8. Product Collection and Storage

[0067] The vacuum-dried nano-cobalt phosphide powder product is collected in storage silo C. During this step, ensure that silo C is clean and airtight to prevent product contamination and loss. The collected nano-cobalt phosphide powder product is properly stored for subsequent processing or use. During storage, the product must be kept dry and moisture-proof to prevent changes in product quality.

[0068] The beneficial effects of the present invention are:

[0069] Efficient preparation and particle size control: The present invention achieves efficient preparation of cobalt hydroxide nanoprecipitates by carefully controlling chemical reaction conditions such as temperature, pH value and reaction time.

[0070] In the further phosphating reaction, the nitrogen is carried and stirred to ensure that the phosphine gas is fully in contact with the cobalt hydroxide powder and the reaction is thorough, thereby producing nano-cobalt phosphide powder with uniform particle size distribution and a particle size of less than 20 nm.

[0071] Uniform particle size: The nano-cobalt phosphide powder prepared by the present invention has a uniform particle size distribution and is less than 20 nm. This is due to the precise pH adjustment of the reaction system in step 4 and the nitrogen stirring in step 10, which ensures that the generated cobalt hydroxide precipitate and the subsequent cobalt phosphide product have uniform particle sizes.

[0072] Reduced raw material waste: Compared with existing technologies, this invention significantly reduces the amount of sodium hypophosphite used. By optimizing the reaction conditions and steps, only a 100% excess of sodium hypophosphite is required for complete reaction, significantly reducing raw material costs and waste emissions.

[0073] Simplified process and mass production: The preparation process of the present invention is relatively simple, with clear and defined steps, easy to operate and control. By utilizing mechanized and automated equipment, such as manipulators, automatic weighing devices, and conveying devices, the entire process from raw material preparation to product collection is automated, significantly improving production efficiency and making it suitable for mass production.

[0074] High product quality: Through meticulous filtration, washing, and drying steps, the purity and quality of the final product are ensured. The resulting nano-cobalt phosphide powder has excellent dispersibility and stability, making it suitable for a variety of applications. BRIEF DESCRIPTION OF THE DRAWINGS

[0075] In order to facilitate understanding by those skilled in the art, the present invention is further described below with reference to the accompanying drawings:

[0076] Figure 1 This is a flow chart of the horizontal tube furnace of the boiling phosphating equipment used in the present invention, corresponding to all embodiments.

[0077] Figure 2 This is the SEM spectrum of the CoP sample obtained in the present invention, corresponding to Example 4.

[0078] Figure 3 : This is the XRD spectrum of the CoP sample obtained in the present invention, corresponding to Example 4.

[0079] Figure 4 The present invention provides a flow chart of the raw material preparation and solution preparation stages in the process method.

[0080] Figure 5 The present invention provides a flow chart of the steps of generating cobalt hydroxide nano-precipitates and collecting and washing the cobalt hydroxide precipitates in the process of the present invention.

[0081] Figure 6 The present invention provides a flow chart of the process method of the present invention, which includes 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. DETAILED DESCRIPTION

[0082] In order to make people in this technical field better understand the technical solution in this application, Figure 1-6 The present invention is further described in detail. The following examples are only used to more clearly illustrate the technical solutions of the present invention and are not intended to limit the scope of protection of the present invention.

[0083] like Figure 1-6 A process for efficiently preparing nano-cobalt phosphide is shown, which includes 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 includes the following steps:

[0084] 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.

[0085] 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.

[0086] Step 3: Pour 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.

[0087] The generation stage of the cobalt hydroxide nanoprecipitate comprises the following steps:

[0088] 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 cobalt chloride to fully react;

[0089] 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.

[0090] The collection and washing stage of the cobalt hydroxide precipitate comprises the following steps:

[0091] Step 1: After the reaction is completed, stirring and heating are stopped, and the generated cobalt hydroxide precipitate is collected by a filtration device, and the cobalt hydroxide precipitate is transported to a chloride ion adsorption tank, and repeatedly washed with distilled water until no chloride ions remain, to ensure the purity of the precipitate;

[0092] Step 2: After washing, the filtered cobalt hydroxide precipitate is transported to the transition bin A for temporary storage. At the same time, the storage bin A is used to store sodium hypophosphite (NaH2PO2) powder to ensure that the sodium hypophosphite is dry and easy to use.

[0093] The pretreatment stage of the cobalt hydroxide and sodium hypophosphite comprises the following steps:

[0094] Step 1: Load the cobalt hydroxide powder into a tall crucible via a robot or automatic conveyor. Then, place the crucible containing the cobalt hydroxide powder into a tube furnace via a robot. Set the heating program and heat the tube furnace to a certain temperature for high-temperature pretreatment to remove moisture and residual gas from the cobalt hydroxide powder.

[0095] Step 2: Take the sodium hypophosphite (NaH2PO2) powder out of storage bin A, put 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.

[0096] The high temperature phosphating reaction stage comprises the following steps:

[0097] Step 1: Evacuate the tubular furnace to remove air and impurities from the furnace, then heat it to a certain temperature to decompose the sodium hypophosphite to produce phosphine (PH3) gas and disodium hydrogen phosphate (Na2HPO4).

[0098] Step 2: Nitrogen (N2) is introduced as a carrier gas into a container containing sodium hypophosphite, causing the phosphine gas produced by the decomposition of the sodium hypophosphite to flow out along with the nitrogen and continue to flow into the bottom of a crucible containing cobalt hydroxide powder; the phosphine gas reacts with the cobalt hydroxide powder at high temperature to produce cobalt phosphide (CoP) and water.

[0099] The stirring and boiling phosphating stage comprises the following steps:

[0100] 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 between the gas and the powder and the reaction efficiency.

[0101] 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.

[0102] The collection and processing stage of the reaction products comprises the following steps:

[0103] Step 1: The generated cobalt phosphide product is collected through a filtration device and sent to a storage bin B; the cobalt phosphide product is screened and filtered to remove impurities and unreacted particles; and finally, the filtered cobalt phosphide product is sent to a vacuum dryer for vacuum drying to remove residual moisture and gas, thereby obtaining a final nano-cobalt phosphide powder product.

[0104] Step 2: Collect the obtained nano-cobalt phosphide powder product into the storage bin C for processing in the next step or storage for future use.

[0105] The workflow of the present invention is as follows: 1. Raw material preparation and solution preparation

[0106] Use high-purity cobalt chloride (CoCl2·6H2O) as the cobalt source. Dissolve a certain amount of cobalt chloride in deionized or distilled water. Accurately weigh and slowly add the solution to ensure complete dissolution, forming a cobalt chloride solution of a certain concentration. The concentration of the cobalt chloride solution should be precisely calculated based on the requirements of subsequent reactions.

[0107] High-purity sodium hydroxide (NaOH) is used as the alkaline source. A certain amount of sodium hydroxide is dissolved in deionized or distilled water to form a sodium hydroxide solution of a certain concentration. Similarly, the concentration of the sodium hydroxide solution must be precisely calculated based on the requirements of the subsequent reaction.

[0108] Use a high-concentration 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.

[0109] 2. Formation of Cobalt Hydroxide Nanoprecipitates

[0110] Under mechanical stirring, the cobalt chloride solution is slowly transferred to Reactor A containing hydrogen peroxide. During this process, the hydrogen peroxide acts as an oxidant, reacting with the cobalt chloride to form an intermediate product. As the cobalt chloride and hydrogen peroxide react, sodium hydroxide solution is added dropwise to adjust the pH of the reaction system to an appropriate range (e.g., approximately 9 or 10). With the addition of sodium hydroxide solution, a brown-black cobalt hydroxide (Co(OH)3) nanoprecipitate gradually forms in the reaction system.

[0111] 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 formation of cobalt hydroxide nanoprecipitates.

[0112] 3. Collection and washing of cobalt hydroxide precipitate

[0113] After the reaction is complete, stirring and heating are stopped. The generated cobalt hydroxide precipitate is collected by filtration. During this process, the cleanliness and integrity of the filtration device must be ensured to avoid the introduction of impurities.

[0114] The collected cobalt hydroxide precipitate is transferred to a chloride ion adsorption tank and repeatedly washed with distilled water until no chloride ions remain. This step is to remove chloride ions and other soluble impurities from the precipitate, ensuring its purity.

[0115] 4. Pretreatment of cobalt hydroxide and sodium hypophosphite

[0116] After washing is completed, the cobalt hydroxide precipitate obtained by filtration is transported to the transition chamber A for temporary storage. In the transition chamber A, the cobalt hydroxide precipitate can be further dried and impurity-removed.

[0117] Storage silo A is used to store sodium hypophosphite (NaH2PO2) powder. Before use, ensure that the sodium hypophosphite is dry and easily accessible. The purity of the sodium hypophosphite can be improved through proper drying and impurity removal.

[0118] 5. High temperature phosphating reaction

[0119] Cobalt hydroxide powder is loaded into a tall crucible using a robot or automated conveyor. The crucible containing the cobalt hydroxide powder is then placed into a tube furnace using a robot. After setting the heating program, the tube furnace is heated to a specific temperature (e.g., 320°C) for high-temperature pretreatment. This step removes moisture and residual gases from the cobalt hydroxide powder, preparing it for the subsequent phosphating reaction.

[0120] Sodium hypophosphite powder is removed from storage silo A and loaded into another tall crucible via an automatic weighing device and conveyor. A robotic arm then places it into another container in a tube furnace. The tube furnace is then evacuated to a vacuum state to remove air and impurities. The sodium hypophosphite is then heated to a certain temperature (e.g., 320°C) to decompose, producing phosphine (PH3) gas and disodium hydrogen phosphate (Na2HPO4).

[0121] Nitrogen (N2) is introduced as a carrier gas into a container containing sodium hypophosphite. Phosphine gas, produced by the decomposition of the sodium hypophosphite, flows out along with the nitrogen and continues to flow into the bottom of a crucible containing cobalt hydroxide powder. The phosphine gas reacts with the cobalt hydroxide powder at high temperatures to produce cobalt phosphide (CoP) and water.

[0122] 6. Stirring and boiling phosphating

[0123] Continuously flowing nitrogen gas keeps the cobalt hydroxide powder in a floating state. Nitrogen not only acts as a carrier gas to carry the phosphine gas into the reaction system but also provides stirring and boiling phosphating. The flow of nitrogen enhances gas-powder contact and reaction efficiency, making the reaction more complete and uniform.

[0124] 7. Collection and treatment of reaction products

[0125] After the reaction is complete, heating and nitrogen flow are stopped. After the tubular furnace cools, the reaction product is removed. The resulting cobalt phosphide product is collected using a filter and transferred to storage bin B. The cobalt phosphide product is screened and filtered to remove impurities and unreacted particles. This step further improves the purity and quality of the product.

[0126] 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.

[0127] 8. Product Collection and Storage

[0128] The vacuum-dried nano-cobalt phosphide powder product is collected in storage silo C. During this step, it is important to ensure that silo C is clean and airtight to prevent product contamination and loss. The collected nano-cobalt phosphide powder product is properly stored for subsequent processing or use.

[0129] The present invention is further described below with reference to examples. Example

[0130] An efficient method for preparing cobalt phosphide is achieved through the following process:

[0131] Dissolve 10g of CoCl2·6H2O in 150mL of water. While mechanically stirring, slowly add 10mL of a 30% H2O2 solution dropwise. Continue stirring and add 5% NaOH solution dropwise until the pH is approximately 9. Collect the resulting precipitate by filtration and wash with distilled water until it is free of chloride ions. Place the filtered precipitate in an autoclave, which is then placed in a 150°C drying oven for 6 hours. Filter, wash, and dry the resulting nano-Co(OH)3 powder. Place it in a tall crucible (designated A) and place it in a tube furnace. Place 100g of sodium hypophosphite (NaH2PO2) powder (9-fold excess) in another container (designated B) in the tube furnace. Evacuate the tube furnace, heat to 320°C, and maintain for 2 hours. N2 is introduced into container B, carrying the generated PH3 gas with it and continuing to flow into the bottom of crucible A. This gas agitates the Co(OH)3 powder, keeping it in a floating state and stirring it, facilitating gas transfer and ensuring a complete reaction. 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. 3.81 g of CoP nanopowder was obtained. Example

[0132] An efficient method for preparing cobalt phosphide is achieved through the following process:

[0133] Dissolve 10g of CoCl2·6H2O in 150mL of water. While mechanically stirring, slowly add 10mL of a 30% H2O2 solution dropwise. Continue stirring and add 5% NaOH solution dropwise until the pH is approximately 9. Collect the resulting precipitate by filtration and wash with distilled water until chloride ions are eliminated. Place the filtered precipitate in an autoclave, which is then placed in a 150°C drying oven for 6 hours. Filter, wash, and dry the resulting nano-Co(OH)3 powder. Place it in a tall crucible (designated A) and place it in a tube furnace. Place 50g of sodium hypophosphite (NaH2PO2) powder (a 4-fold excess) in another container (designated B) within the tube furnace. Evacuate the tube furnace, heat to 320°C, and maintain for 1.5 hours. N2 is then introduced into container B, carrying the generated PH3 gas with it and continuing to flow into the bottom of crucible A. This gas agitates the Co(OH)3 powder, keeping it in a floating state and stirring it, facilitating gas transfer and ensuring a complete reaction. 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. 3.81 g of CoP nanopowder was obtained. Example

[0134] An efficient method for preparing cobalt phosphide is achieved through the following process:

[0135] Dissolve 10g of CoCl2·6H2O in 150mL of water. While mechanically stirring, slowly add 10mL of a 30% H2O2 solution dropwise. Continue stirring and add 5% NaOH solution dropwise until the pH is approximately 10. Collect the resulting precipitate by filtration and wash with distilled water until chloride ions are eliminated. Place the filtered precipitate in an autoclave, which is then placed in a 150°C drying oven for 6 hours. Filter, wash, and dry the resulting nano-Co(OH)3 powder. Place it in a tall crucible (designated A) and place it in a tube furnace. Place 30g of sodium hypophosphite (NaH2PO2) powder (a 2-fold excess) in another container (designated B) within the tube furnace. Evacuate the tube furnace, heat to 320°C, and maintain for 1 hour. N2 is introduced into container B, carrying the generated PH3 gas with it and continuing to flow into the bottom of crucible A. This gas agitates the Co(OH)3 powder, keeping it in a floating state and stirring it, facilitating gas transfer and ensuring a complete reaction. 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. 3.82 g of CoP nanopowder was obtained. Example

[0136] An efficient method for preparing cobalt phosphide is achieved through the following process:

[0137] Dissolve 10g of CoCl2·6H2O in 150mL of water. While mechanically stirring, slowly add 10mL of a 30% H2O2 solution dropwise. Continue stirring and add 5% NaOH solution dropwise until the pH is approximately 10. Collect the resulting precipitate by filtration and wash with distilled water until chloride ions are eliminated. Place the filtered precipitate in an autoclave, which is then placed in a 150°C drying oven for 6 hours. Filter, wash, and dry the resulting nano-Co(OH)3 powder. Place it in a tall crucible (designated A) and place it in a tube furnace. Place 20g of sodium hypophosphite (NaH2PO2) powder (a 100% excess) in another container (designated B) within the tube furnace. Evacuate the tube furnace, heat to 320°C, and maintain for 0.5h. N2 is then introduced into container B, carrying the generated PH3 gas with it and continuing to flow into the bottom of crucible A. This gas agitates the Co(OH)3 powder, keeping it in a floating state and stirring it, facilitating gas transfer and ensuring a complete reaction. 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. 3.82 g of CoP nanopowder was obtained.

[0138] The present invention is not limited to the above-mentioned embodiments. On the basis of the technical solutions disclosed in the present invention, those skilled in the art can make some substitutions and modifications to some of the technical features therein according to the disclosed technical content without creative labor, and these substitutions and modifications are all within the protection scope of the present invention.

Claims

1. A process for preparing nano-cobalt phosphide, characterized in that: The process method includes 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 includes the following steps: Step 1: Prepare cobalt chloride hexahydrate 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; Step 3: Pour 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; The generation stage of the cobalt hydroxide nanoprecipitate 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 cobalt chloride to fully react; Step 2: Then, sodium hydroxide solution is added dropwise to adjust the pH value of the reaction system to 9 or 10; during the reaction, brown-black cobalt hydroxide nanoprecipitates are generated; The collection and washing stage of the cobalt hydroxide precipitate comprises the following steps: Step 1: After the reaction is completed, stirring and heating are stopped, and the generated cobalt hydroxide precipitate is collected by a filtration device, and the cobalt hydroxide precipitate is transported to a chloride ion adsorption tank, and repeatedly washed with distilled water until no chloride ions remain, to ensure the purity of the precipitate; Step 2: After washing is completed, the filtered cobalt hydroxide precipitate is transported to the transition bin A for temporary storage. At the same time, the storage bin A is used to store the sodium hypophosphite powder to ensure that the sodium hypophosphite is dry and easy to use.

2. The process for preparing nano-cobalt phosphide according to claim 1, wherein: The pretreatment stage of the cobalt hydroxide and sodium hypophosphite comprises the following steps: Step 1: Load the cobalt hydroxide powder into a tall crucible via a robot or automatic conveyor. Then, place the crucible containing the cobalt hydroxide powder into a tube furnace via a robot. Set the heating program and heat the tube furnace to a certain temperature for high-temperature pretreatment to remove moisture and residual gas from the cobalt hydroxide powder. Step 2: Take the sodium hypophosphite powder out of storage bin A, put 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.

3. The process for preparing nano-cobalt phosphide according to claim 1, wherein: 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 gas and disodium hydrogen phosphate; Step 2: Nitrogen is introduced as a carrier gas into a container containing sodium hypophosphite, causing the phosphine gas produced by the decomposition of the sodium hypophosphite to flow out along with the nitrogen and continue to flow into the bottom of a crucible containing cobalt hydroxide powder; the phosphine gas reacts with the cobalt hydroxide powder at a high temperature to produce cobalt phosphide and water.

4. The process for preparing nano-cobalt phosphide according to claim 1, wherein: 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 between the gas and the powder and the reaction efficiency. 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.

5. The process for preparing nano-cobalt phosphide according to claim 1, wherein: The collection and processing stage of the reaction products comprises the following steps: Step 1: The generated cobalt phosphide product is collected through a filtration device and sent to a storage bin B; the cobalt phosphide product is screened and filtered to remove impurities and unreacted particles; and finally, the filtered cobalt phosphide product is sent to a vacuum dryer for vacuum drying to remove residual moisture and gas, thereby obtaining a final nano-cobalt phosphide powder product. Step 2: Collect the obtained nano-cobalt phosphide powder product into the storage bin C for processing in the next step or storage for future use.

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