Cobalt phosphide heterojunction catalyst and preparation method and application thereof
By preparing a cobalt phosphide heterojunction catalyst, the problems of catalyst separation and poor stability in the electrochemical recycling of PET were solved, achieving efficient synergistic enhancement of plastic oxidation and hydrogen evolution reaction, improving the stability and activity of the catalyst, simplifying the preparation process and reducing costs.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-12-08
- Publication Date
- 2026-03-10
AI Technical Summary
In existing PET electrochemical recycling systems, the catalyst system is separate, making it difficult to simultaneously optimize PET oxidation kinetics and HER reaction efficiency. Precious metal catalysts are costly and have poor stability, while non-precious metal catalysts are prone to corrosion and passivation, resulting in short catalyst life and hindering industrial-scale implementation.
A cobalt phosphide heterojunction catalyst preparation method is adopted. The method involves pretreating a three-dimensional porous conductive substrate, preparing a mixed impregnation solution containing cobalt and phosphorus sources, drying after standing, and phosphating under an inert atmosphere to form a cobalt phosphide heterojunction active layer. This method simplifies the preparation process, reduces costs, and ensures that the active components are tightly bonded to the substrate.
In-situ growth and firm anchoring of cobalt phosphide nanoparticles were achieved, which improved the long-term operational stability and catalytic activity of the catalyst in the electrocatalytic plastic recycling system, optimized the synergistic enhancement of plastic oxidation and hydrogen evolution reaction, and improved the selectivity and stability of the catalyst.
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Figure CN121629441A_ABST
Abstract
Description
TECHNICAL FIELD
[0001] The present disclosure relates to the technical field of catalyst preparation, in particular to a cobalt phosphide heterojunction catalyst and a preparation method and application thereof. BACKGROUND
[0002] As a key path for resource recycling and pollution control, electrochemical recycling of plastics technology converts waste plastics into high-value-added chemicals through electrocatalysis, greatly reducing energy consumption while realizing waste-to-resource, and providing a green solution to the problem of plastic pollution. Among them, polyethylene terephthalate (PET) is the highest-yielding polyester plastic, and its efficient conversion not only can alleviate the ecological pressure brought by white pollution, but also can supplement the shortage of chemical raw materials, which has important strategic significance for sustainable use of resources.
[0003] In the existing PET electrochemical recycling system, the cooperative mode of anodic electro-oxidation and cathodic hydrogen evolution is generally adopted. The anode converts PET hydrolysis products into target products such as terephthalic acid (PTA) or formate, and the cathode simultaneously undergoes a hydrogen evolution reaction (HER), forming a double-value closed loop of resource recycling and energy production. However, the current process is difficult to realize industrialization, for example, the catalyst system is separate, and the current process needs to use anode catalysts (such as Pt / C) and cathode catalysts (such as Pt / C, NiMo alloy) respectively, which not only increases equipment investment and process complexity, but also due to the lack of efficient dual-function catalysts, it is difficult to simultaneously optimize the PET oxidation kinetics and the HER reaction efficiency. For example, the use of Pt, Although noble metals such as Pt, Pd, and Au have certain activity, they cannot balance the dual needs of plastic derivative adsorption and hydrogen adsorption free energy. Non-noble metal catalysts lack stability, and transition metal oxides and other non-noble metal materials can reduce costs, but are prone to anode corrosion and cathode passivation, resulting in short catalyst life and poor reaction sustainability.
[0004] Therefore, it is urgent to develop non-noble metal dual-function catalysts with high activity, selectivity, and stability to break through the industrialization bottleneck of electrochemical plastic recycling. SUMMARY
[0005] The present disclosure provides a cobalt phosphide heterojunction catalyst and a preparation method and application thereof to at least solve the above technical problems existing in the prior art.
[0006] According to a first aspect of the present disclosure, a preparation method of a cobalt phosphide heterojunction catalyst is provided, the method comprising: pretreating a three-dimensional porous conductive substrate to remove organic contaminants and oxide layers on the surface of the three-dimensional porous conductive substrate; Prepare a mixed impregnation solution containing cobalt source and phosphorus source; immerse the pretreated three-dimensional porous conductive substrate in the mixed impregnation solution and let it stand at room temperature for 6 to 12 hours to load the cobalt source and phosphorus source onto the surface of the three-dimensional porous conductive substrate; The impregnated three-dimensional porous conductive substrate is removed and dried, so that the loaded cobalt source and phosphorus source are fixed in crystal form on the surface of the three-dimensional porous conductive substrate. The dried three-dimensional porous conductive substrate is placed in a container and heated to 300~350℃ under an inert atmosphere and kept at that temperature for 1~2 hours to reduce and phosphate the cobalt source, so as to generate a cobalt phosphide heterojunction active layer on the substrate surface. After the phosphating reaction is completed, the catalyst is cooled under an inert atmosphere, cleaned and purified to obtain a cobalt phosphide heterojunction catalyst.
[0007] In one embodiment, the pretreated three-dimensional porous conductive substrate includes: The three-dimensional porous conductive substrate was subjected to ultrasonic cleaning in organic cleaning agent, acidic cleaning agent, polar solvent and deionized water in turn to remove organic contaminants and oxide layer on the surface of the three-dimensional porous conductive substrate.
[0008] In one embodiment, the molar ratio of cobalt source to phosphorus source in the mixed impregnation solution is 1:10 to 1:20.
[0009] In one embodiment, the three-dimensional porous conductive substrate is any one of foamed metal, porous carbon material, or porous ceramic-based conductive material; the foamed metal is any one of foamed nickel, foamed copper, or foamed iron.
[0010] In one embodiment, the cobalt source is any one or a mixture of cobalt nitrate, chloride, sulfate or carboxylate; the phosphorus source is hypophosphite.
[0011] In one possible embodiment, the cobalt phosphide heterojunction is Heterojunction, the Heterojunctions are loaded on the surface of a three-dimensional porous conductive substrate.
[0012] In one embodiment, placing the dried three-dimensional porous conductive substrate in a container and heating it to 300-350°C under an inert atmosphere, holding it at that temperature for 1-2 hours, includes: A segmented temperature-controlled phosphating process is adopted. First, the temperature is increased to 250-280℃ at a rate of 2-3℃ / min, and then held for 0.5-1 hour to allow the phosphorus source to slowly decompose and initially react with the cobalt source to form phosphorus. Intermediate; then heat to 320-350℃ at a rate of 3-5℃ / min, and hold for 1-1.5 hours, so that... Further phosphating Heterogeneous junction.
[0013] According to a second aspect of this disclosure, a cobalt phosphide heterojunction catalyst is provided, which is prepared according to the above-described preparation method.
[0014] According to a third aspect of this disclosure, an application of a cobalt phosphide heterojunction catalyst in electrocatalytic plastic recycling and hydrogen evolution is provided, wherein the cobalt phosphide heterojunction catalyst serves as the anode electrode and / or cathode electrode of the electrolysis system.
[0015] In one embodiment, the electrocatalytic plastic recycling and hydrogen evolution reaction are carried out in an alkaline electrolyte.
[0016] This disclosure provides a cobalt phosphide heterojunction catalyst, its preparation method, and its application. The preparation method first involves pretreating a three-dimensional porous conductive substrate to remove organic contaminants and oxide layers from its surface, preventing interference from impurities on subsequent cobalt and phosphorus source loading and ensuring a tight bond between the active components and the substrate. Then, a mixed impregnation solution containing cobalt and phosphorus sources is prepared, and the pretreated three-dimensional porous conductive substrate is immersed in the solution and allowed to stand at room temperature for 6-12 hours, allowing the cobalt and phosphorus sources to be adsorbed and loaded onto the surface of the three-dimensional porous conductive substrate. This room-temperature static impregnation method eliminates the need for heating, pressurization, or complex stirring equipment; efficient loading of the cobalt and phosphorus sources is achieved solely through capillary action and physical adsorption. The impregnated three-dimensional porous conductive substrate is then removed and dried, allowing the loaded cobalt and phosphorus sources to be fixed in crystalline form on the surface of the substrate. The dried substrate is then placed in a container and heated to 300-350°C under an inert atmosphere, held for 1-2 hours to reduce and phosphate the cobalt source, forming a cobalt phosphide heterojunction active layer on the substrate surface. After the phosphating reaction, the substrate is cooled to room temperature under an inert atmosphere to obtain the cobalt phosphide heterojunction catalyst. This innovative approach uses a "one-pot" impregnation method to load the cobalt and phosphorus sources onto the support in a single process, followed by phosphating treatment, ultimately forming a uniform cobalt phosphide heterojunction active layer without significant agglomeration on the substrate surface. Because the active precursor and phosphorus source are confined together within the porous structure, The gas generation and phosphating reaction occur within the confined space of the support framework, enabling in-situ growth and firm anchoring of cobalt phosphide nanoparticles. This strong interaction effectively prevents the shedding and deactivation of active materials during electrocatalysis (especially under severe gas evolution conditions), significantly improving the long-term operational stability of the catalyst in harsh electrocatalytic plastic recycling systems.
[0017] It should be understood that the description in this section is not intended to identify key or essential features of the embodiments of this disclosure, nor is it intended to limit the scope of this disclosure. Other features of this disclosure will become readily apparent from the following description. Attached Figure Description
[0018] The above and other objects, features, and advantages of this disclosure will become readily apparent from the following detailed description of exemplary embodiments, taken in conjunction with the accompanying drawings. Several embodiments of this disclosure are illustrated in the drawings by way of example and not limitation, in which: In the accompanying drawings, the same or corresponding reference numerals indicate the same or corresponding parts.
[0019] Figure 1 The cobalt phosphide heterojunction catalyst in Example 1 of this application A schematic diagram of the preparation process of @NF; Figure 2 This is a schematic diagram of the preparation process of the cobalt phosphide catalyst CoP@NF in Comparative Example 1; Figure 3 Cobalt phosphide catalyst in Comparative Example 2 A schematic diagram of the preparation process of @NF; Figure 4 The cobalt phosphide heterojunction catalyst in Example 1 of this application XRD pattern of @NF; Figure 5 The XRD pattern of the cobalt phosphide catalyst CoP@NF in Comparative Example 1 is shown. Figure 6 Cobalt phosphide catalyst in Comparative Example 2 XRD pattern of @NF; Figure 7 The cobalt phosphide heterojunction catalyst in Example 1 of this application HRTEM map of @NF; Figure 8 The HRTEM spectrum of the cobalt phosphide catalyst CoP@NF in Comparative Example 1 is shown. Figure 9 Cobalt phosphide catalyst in Comparative Example 2 HRTEM map of @NF; Figure 10 This is a schematic diagram of a catalytic plastic recycling and hydrogen evolution system; Figure 11 The cobalt phosphide heterojunction catalyst prepared in Example 1 LSV spectra of @NF and carrier NF at the anode of an electrolytic cell for the oxidation of waste plastic hydrolysate; Figure 12 The cobalt phosphide heterojunction catalyst prepared in Example 1 @NF and the catalyst CoP@NF prepared in Comparative Examples 1 and 2, @NF LSV spectrum of oxidation of waste plastic hydrolysate at the anode of an electrolytic cell; Figure 13 The cobalt phosphide heterojunction catalyst prepared in Example 1 LSV spectra of @NF and support NF at the cathode of the electrolytic cell for hydrogen evolution in potassium hydroxide solution; Figure 14 The cobalt phosphide heterojunction catalyst prepared in Example 1 @NF and the catalyst CoP@NF prepared in Comparative Examples 1 and 2, @NF LSV spectrum of hydrogen evolution in potassium hydroxide solution at the cathode of an electrolytic cell; Figure 15 The cobalt phosphide heterojunction catalyst prepared in Example 1 When @NF is used as both an anode and cathode electrode in an electrochemical recovery system coupled with a cathode hydrogen evolution, the Faraday efficiency (FE) and selectivity of formic acid, the electrochemical conversion product of the anode plastic hydrolysate, at different potentials are analyzed. Figure 16 The cobalt phosphide heterojunction catalyst prepared in Example 1 When @NF is used as both an anode and cathode electrode in an electrochemical recovery system coupled with a cathode hydrogen evolution, the Faraday efficiency FE and selectivity of formic acid, the electrochemical conversion product of the anode plastic hydrolysate, are measured when different charges pass through it. Figure 17 To reveal DFT calculation of the synergistic effect of the heterojunction interface, where (a) Figure CoP(011), (201) and Atomic models of the clean surface, H* adsorption surface, and *CHO-CHO adsorption surface of the heterojunction; (b) Calculated adsorption energy (Eads) of the *CHO-CHO intermediate in EGOR; (ce) The d orbital centers (εd) shown in the projected density of states (PDOS) plot are as follows: (c) Heterojunction, (d)CoP(011), (e) (201); (f) Figure shows the calculated free energy diagram (ΔG) for the HER Volmer step (H* adsorption); (g) Figure shows... Two-dimensional charge density difference analysis of the interface (isosurface: (Yellow: accumulation, cyan: depletion) and their corresponding line outlines. Detailed Implementation
[0020] To make the objectives, features, and advantages of this disclosure more apparent and understandable, the technical solutions in the embodiments of this disclosure will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of this disclosure, and not all of them. All other embodiments obtained by those skilled in the art based on the embodiments of this disclosure without creative effort are within the scope of protection of this disclosure.
[0021] Electrochemical recycling of plastics is a key technology for the resource utilization of waste plastics. However, existing electrocatalytic technologies rely on separate catalysts for the anode and cathode, which not only increases equipment and costs but also makes it difficult to simultaneously optimize reaction efficiency. On the other hand, while precious metal catalysts are active, they have high energy consumption and costs, while non-precious metal catalysts are prone to corrosion, passivation, and poor stability. To overcome this dilemma, there is an urgent need for non-precious metal bifunctional catalysts with suitable performance, and cobalt phosphide heterojunctions have become a potential direction due to their combined oxidation and hydrogen evolution activities. However, the preparation methods of cobalt phosphide heterojunctions in related technologies require multiple steps, including precursor synthesis, mixed phosphorus source, and high-temperature phosphating. These steps are cumbersome, costly, and difficult to control product uniformity, making it difficult to scale up their application in electrocatalytic recycling scenarios. Based on this, this disclosure provides a method for preparing a cobalt phosphide heterojunction catalyst, aiming to simplify the preparation process, reduce costs, and ensure product performance, thus providing a suitable catalyst solution for electrocatalytic plastic recycling. This disclosure provides a method for preparing a cobalt phosphide heterojunction catalyst, comprising the following steps: Step 1: Pre-treat the three-dimensional porous conductive substrate to remove organic contaminants and oxide layers from the surface of the three-dimensional porous conductive substrate.
[0022] The purpose of pretreating the substrate is to ensure its cleanliness and the loading efficiency of the active components. The three-dimensional porous conductive substrate can be any one of foamed metal (foamed nickel, foamed copper, or foamed iron), porous carbon materials, or porous ceramic-based conductive materials.
[0023] In one example, a three-dimensional porous conductive substrate is ultrasonically cleaned sequentially in an organic cleaning agent, an acidic cleaning agent, a polar solvent, and deionized water. For example, taking nickel foam as an example, the cleaning process involves first ultrasonically cleaning it with acetone or anhydrous ethanol at a power of 150-200W for 15-20 minutes to remove organic contaminants, then ultrasonically cleaning it with 5%-10% dilute hydrochloric acid or dilute sulfuric acid for 10-15 minutes to remove the oxide layer, and finally ultrasonically cleaning it with ethanol and deionized water for 10-15 minutes each, followed by rinsing it multiple times with deionized water.
[0024] Step 2: Prepare a mixed impregnation solution containing cobalt source and phosphorus source; immerse the pretreated three-dimensional porous conductive substrate in the mixed impregnation solution and let it stand at room temperature for 6 to 12 hours to load the cobalt source and phosphorus source onto the surface of the three-dimensional porous conductive substrate.
[0025] This step aims to achieve uniform co-loading of the cobalt and phosphorus sources. The raw materials selected are cobalt sources with high solubility and no impurities during thermal decomposition, such as any one or more mixtures of cobalt nitrates, chlorides, sulfates, or carboxylates; the phosphorus source is hypophosphite. Specifically, the cobalt source is cobalt nitrate hexahydrate, cobalt chloride, or cobalt acetate, and the phosphorus source is such as sodium hypophosphite, potassium hypophosphite, or ammonium hypophosphite. During impregnation, the three-dimensional conductive porous substrate is immersed and sealed for 6-12 hours. After completion, excess liquid is removed by natural dripping for 1-2 minutes to prevent precursor agglomeration after drying.
[0026] In a specific example, cobalt nitrate hexahydrate was used as the cobalt source, and sodium hypophosphite ( Hydrothermal-calcination synthesis using phosphorus source During the process, sodium phosphate decomposes at high temperature to produce phosphine ( ) gas. The gas diffuses into the hydrothermally pretreated nickel foam (whose surface typically has a layer of cobalt hydroxide or oxide, such as CoOOH or...). )surface. The phosphorus atoms in the molecule possess lone pairs of electrons, which can undergo coordination adsorption with metal sites on the surface of cobalt oxide. During the subsequent high-temperature argon calcination stage, the adsorbed... The molecules undergo thermal decomposition, and their strong reducing properties first break down cobalt oxides (such as...). Partially reduced to lower valence cobalt species (such as...) even Simultaneously, it undergoes self-dehydrogenation. The dehydrogenation process generates highly reactive phosphorus radicals or low-valent phosphorus species. These reactive phosphorus species react with the reduced cobalt atoms or low-valent cobalt ions to form Co-P bonds, and ultimately crystallize into the target product. It is worth noting that the initial valence state of cobalt, the degree of reduction, and the local phosphorus / cobalt ratio in the cobalt precursor jointly determine whether the final product is CoP. Or is it a heterojunction of the two? .
[0027] Step 3: Remove and dry the impregnated three-dimensional porous conductive substrate so that the loaded cobalt source and phosphorus source are fixed in crystal form on the surface of the three-dimensional porous conductive substrate.
[0028] Treat with a 60-80℃ forced-air drying oven or vacuum drying oven for 2-4 hours. During operation, the three-dimensional porous conductive substrate should be laid flat or suspended to avoid stacking, ensuring uniform heating. After drying, cool to room temperature.
[0029] Step 4: Place the dried three-dimensional porous conductive substrate in a container, heat it to 300~350℃ under an inert atmosphere, and keep it at that temperature for 1~2 hours to reduce and phosphate the cobalt source, so as to generate a cobalt phosphide heterojunction active layer on the substrate surface. This step involves in-situ vapor-phase phosphating to form a cobalt phosphide heterojunction active layer. The dried three-dimensional porous conductive substrate treated in step 3 is placed in the middle of a quartz boat in a tubular furnace. An inert atmosphere is first introduced at a certain flow rate to remove air from the inside of the furnace, for example, by purging with high-purity argon or nitrogen at a rate of 200-300 mL / min for 15-20 minutes. Then, the temperature is programmed to rise to 300-350°C at a rate of 2-5°C / min and held for 1-2 hours. During this process, the sodium hypophosphite loaded on the substrate undergoes thermal decomposition to generate highly active... The gas directly reduces and phosphates the adjacent cobalt oxide / salt precursor in situ, ultimately forming a uniform and firmly bonded heterojunction cobalt phosphide on the surface of the nickel foam skeleton. @NF) Active layer. The phosphating temperature is set to 300~350℃. If the temperature is below 300℃, the phosphating will be insufficient; if the temperature is above 350℃, it will easily lead to an imbalance in the heterojunction ratio.
[0030] Step 5: After the phosphating reaction is completed, the mixture is cooled under an inert atmosphere, cleaned to remove impurities, and then a cobalt phosphide heterojunction catalyst is obtained.
[0031] After the reaction is complete, the catalyst is cooled to room temperature under a protective atmosphere and then washed with deionized water or anhydrous ethanol to remove impurities formed on the catalyst surface. This is because the decomposition of sodium hypophosphite leaves sodium phosphate and unreacted sodium hypophosphite byproducts on the substrate surface. These byproducts are ionic crystals that dissolve and ionize in aqueous solution; if they remain on the catalyst, they will cause serious interference in electrocatalytic testing. After cleaning and drying, the cobalt phosphide heterojunction catalyst is obtained. As a self-supporting electrode, it can be directly used in electrocatalytic plastic recycling reactions without any subsequent coating or treatment.
[0032] In the above scheme, the three-dimensional porous conductive substrate is first pretreated to remove organic contaminants and oxide layers from its surface, thus avoiding interference from impurities on the subsequent loading of cobalt and phosphorus sources and ensuring a tight bond between the active components and the substrate. Then, a mixed impregnation solution containing cobalt and phosphorus sources is prepared, and the pretreated three-dimensional porous conductive substrate is immersed in the solution and left to stand at room temperature for 6–12 hours, allowing the cobalt and phosphorus sources to be adsorbed and loaded onto the surface of the substrate. This room-temperature static impregnation method eliminates the need for heating, pressurization, or complex stirring equipment; efficient loading of the cobalt and phosphorus sources is achieved solely through capillary action and physical adsorption. The impregnated three-dimensional porous conductive substrate is then removed and dried, allowing the loaded cobalt and phosphorus sources to be fixed in crystalline form on the surface of the substrate. The dried substrate is then placed in a container and heated to 300-350°C under an inert atmosphere, held for 1-2 hours to reduce and phosphate the cobalt source, forming a cobalt phosphide heterojunction active layer on the substrate surface. After the phosphating reaction, the substrate is cooled to room temperature under an inert atmosphere to obtain the cobalt phosphide heterojunction catalyst. This innovative approach uses a "one-pot" impregnation method to load the cobalt and phosphorus sources onto the support in a single process, followed by phosphating treatment, ultimately forming a uniform cobalt phosphide heterojunction active layer without significant agglomeration on the substrate surface. Because the active precursor and phosphorus source are confined together within the porous structure, The gas generation and phosphating reaction occur within the confined space of the support framework, enabling in-situ growth and firm anchoring of cobalt phosphide nanoparticles. This strong interaction effectively prevents the shedding and deactivation of active materials during electrocatalysis (especially under severe gas evolution conditions), significantly improving the long-term operational stability of the catalyst in harsh electrocatalytic plastic recycling systems.
[0033] In one example, the molar ratio of cobalt source to phosphorus source in the mixed impregnation solution is 1:10 to 1:20.
[0034] By controlling the ratio of cobalt source to phosphorus source in the impregnation solution, the active component is uniformly distributed in the form of precursors on the three-dimensional framework of high specific surface area nickel foam. Since the cobalt source and phosphorus source are jointly confined within the porous structure of the nickel foam, The gas generation and phosphating reaction occur within the confined space of the support framework, enabling in-situ growth and firm anchoring of cobalt phosphide nanoparticles. This strong interaction effectively prevents the shedding and deactivation of active materials during electrocatalysis, significantly improving the long-term operational stability of the catalyst in harsh electrocatalytic plastic recycling systems.
[0035] Meanwhile, the preparation method of the cobalt phosphide heterojunction catalyst disclosed herein avoids the use of polymer binders required in the preparation of traditional powder catalysts, completely eliminating the performance degradation problem caused by binders covering active sites or blocking mass transfer channels, ensuring full exposure of all active sites, providing an ideal interface for the adsorption and activation of plastic macromolecules and their intermediate products, thereby endowing them with excellent electrocatalytic activity.
[0036] In one example, a cobalt phosphide heterojunction is Heterojunction, wherein the heterojunction is loaded on the surface of a three-dimensional porous conductive substrate in the form of a nanoflower-like, nanosheet-like, or nanoparticle-like structure.
[0037] The cobalt phosphide heterostructure prepared by the method disclosed herein is specifically as follows: A heterojunction, which is tightly loaded onto the surface of a three-dimensional porous conductive substrate, in one example, Heterojunctions can be loaded onto the substrate surface in the form of nanoflower-like, nanosheet-like, or nanoparticle-like structures. Their unique structure originates from the synergistic regulation of each step in the fabrication process. Specifically, the uniform co-loading of cobalt and phosphorus sources in step 2 provides a basis for a uniform precursor distribution in the heterojunction. The low-to-medium temperature phosphating at 300–350 °C and the gentle heating rate of 2–5 °C / min in step 4 provide a suitable kinetic environment for crystal growth. At excessively low temperatures, crystals are more likely to form… The main nanoparticles tend to form CoP nanosheets at excessively high temperatures, but the process parameters in this method can precisely control the interaction between CoP and nanosheets. The formation of this multi-morphological structure not only fully exposes the active sites at the heterojunction interface, but also utilizes the pore structure of the three-dimensional porous substrate to construct continuous mass transfer channels, reducing the diffusion resistance of reactants and products in the electrocatalytic reaction. Simultaneously, the nanoscale morphological features significantly increase the specific surface area, further enhancing catalytic activity. Furthermore, the tightly loaded structural characteristics prevent the heterojunction from detaching during long-term electrocatalytic cycling. Combined with the inert atmosphere cooling in step 5 to ensure structural integrity, this heterojunction can stably achieve both plastic oxidation and hydrogen evolution in the electrocatalytic plastic recycling reaction, and can also be adapted to different reaction requirements through structural regulation.
[0038] This disclosure also provides Applications of heterojunction catalysts in electrocatalytic plastic recycling and hydrogen evolution, among which Heterojunction catalysts are used as the anode and / or cathode electrodes in the electrolysis system.
[0039] The heterojunction catalyst induces the downward shift of the d-band center at the heterojunction interface, simultaneously optimizing the adsorption energy of plastic-derived intermediates and the hydrogen adsorption free energy, thereby achieving synergistic enhancement of PET conversion and hydrogen evolution reaction.
[0040] In one example, the electrolysis system includes: An electrolytic cell, wherein the electrolytic cell is divided into an anode chamber and a cathode chamber by a cation exchange membrane, the anode chamber being used to hold the plastic hydrolysate and the cathode chamber being used to hold the potassium hydroxide solution; Anode, which is inserted into the anode chamber; Cathode, the cathode being inserted into the cathode chamber; A reference electrode, inserted into the cathode chamber, is used to monitor the cathode potential; A platinum sheet counter electrode is inserted into the cathode chamber to assist the cathode reaction; An electrochemical workstation is connected to the anode electrode, the reference electrode, and the platinum sheet counter electrode, respectively.
[0041] Specifically, the electrocatalytic plastic recycling and hydrogen evolution system includes: a computer, a Chi660E Chenhua electrochemical workstation, an H-type electrolytic cell, a cation exchange membrane, a mercury / mercury oxide reference electrode, a platinum sheet counter electrode, a cathode electrode, and an anode electrode.
[0042] The specific connection method for the electrocatalytic plastic recycling and hydrogen evolution system is as follows: A cation exchange membrane is placed in an H-type electrolytic cell, which is then divided into two pools. One pool contains the hydrolysate of waste plastic, and the other contains a potassium hydroxide solution. The anode and cathode electrodes are placed in the hydrolysate of waste plastic and the potassium hydroxide solution pool, respectively. The working electrode clamp of the electrochemical workstation is attached to the anode electrode immersed in the hydrolysate of waste plastic, and the reference and counter electrode clamps are simultaneously attached to the cathode electrode immersed in the potassium hydroxide solution. Finally, the electrochemical workstation is connected to a computer. The electrochemical workstation is connected to the anode and cathode via the electrode clamps, forming a closed circuit, allowing electrons to flow from the anode to the cathode.
[0043] In one example, one or both of the anode electrode and the cathode electrode are... Heterojunction catalyst. When the anode electrode is When using a heterojunction catalyst, the corresponding cathode electrode is a platinum sheet electrode; when the cathode electrode is... When using a heterojunction catalyst, the corresponding anode electrode is a platinum sheet electrode.
[0044] when When a heterojunction is used as an anode catalyst, The heterojunction optimizes the ethylene glycol oxidation pathway through interfacial electronic reconstruction: its CoP phase P sites preferentially adsorb ethylene glycol α-OH groups, while... Electron-rich Co sites capture CH bonds, achieving spatial specialization of adsorption sites. The heterointerface induces the downward shift of the d-band center, triggering directional electron transfer and forming bifunctional activation centers. Electron-deficient sites... Strengthening CH bond breaking, electron-rich Stable key intermediates This synergistically promotes the improvement of C / C bond breaking efficiency. The interfacial electric field simultaneously compresses the intermediate residence time and raises the dimerization barrier of by-products, increasing the formate selectivity to >86%. Essentially, the heterojunction reconstructs the series reaction into parallel catalysis: CoP specializes in CH cleavage. A stable intermediate is formed, and the interfacial electric field locks the main reaction channel, achieving a three-in-one synergistic effect of "adsorption-bond breaking-conversion".
[0045] When a heterojunction is used as the cathode electrode, the hydrogen evolution reaction (HER) pathway is significantly optimized through interfacial electron redistribution. Specifically, the CoP phase provides strong hydrogen adsorption sites, effectively promoting proton adsorption (Volmer step), while... The phase provides suitable hydrogen adsorption sites, accelerating subsequent hydrogen molecule generation (Heyrovsky / Tafel step). This synergistic effect balances the overall hydrogen adsorption free energy at the interface to near-ideal levels. Simultaneously, the built-in electric field formed at the heterojunction guides protons (H... ＋ ) Targeted migration to Defect sites enhance proton transport flux. Furthermore, the unique open framework structure of the nanoflower exposes highly active crystal faces, increasing the density of active sites. Its interlaced nanosheets also provide rapid escape channels for hydrogen bubbles, significantly reducing the desorption energy barrier.
[0046] In one example, the plastic hydrolysate is prepared by hydrothermal reaction of plastic in a potassium hydroxide solution, wherein the plastic includes one or more of polyethylene terephthalate (PET), polybutylene terephthalate (PBT), and polypropylene terephthalate (PTT). The mass-to-volume ratio of the plastic to the potassium hydroxide solution is 1:(40~70) g / mL, and the concentration of the potassium hydroxide solution is 1 mol / L.
[0047] The present application will now be described in further detail with reference to the accompanying drawings and specific embodiments.
[0048] Example 1 A method for preparing a cobalt phosphide heterojunction catalyst, wherein the cobalt phosphide is... ,like Figure 1 The image shows a cobalt phosphide heterojunction catalyst. A schematic diagram of the preparation process of @NF, which includes: S1. Place the nickel foam in an ultrasonic container and sonicate with anhydrous ethanol at 150~200W for 15 minutes to remove organic pollutants. Then sonicate with dilute hydrochloric acid at a mass fraction of 5%~10% for 10 minutes to remove the oxide layer. Finally, sonicate with ethanol for 15 minutes, then sonicate with deionized water for 10 minutes, and rinse with deionized water several times to obtain pretreated nickel foam.
[0049] S2. Dissolve 41.48 mg of cobalt nitrate hexahydrate and 0.15 g of sodium hypophosphite in deionized water to prepare a mixed impregnation solution containing cobalt and phosphorus sources; immerse the pretreated nickel foam in the mixed impregnation solution and let it stand at room temperature for 9 hours to allow the cobalt and phosphorus sources to be adsorbed onto the surface of the nickel foam. S3. Remove the impregnated nickel foam and dry it to fix the loaded cobalt and phosphorus sources onto the surface of the nickel foam in crystal form. S4. Place the dried nickel foam substrate in a container and heat it to 300~350℃ at a rate of 2-5℃ / min under an argon atmosphere. Hold it at this temperature for 1-2 hours to reduce and phosphate the cobalt source, so as to generate a cobalt phosphide heterojunction active layer on the surface of the nickel foam. S5. After the phosphating reaction is complete, the mixture is cooled to room temperature under an argon atmosphere, washed several times with deionized water, and dried to obtain a cobalt phosphide heterojunction catalyst, denoted as [catalyst name missing]. @NF.
[0050] Comparative Example 1 A method for preparing a cobalt phosphide catalyst, wherein the cobalt phosphide is CoP, such as... Figure 2 The diagram shows a schematic of the preparation process of the cobalt phosphide catalyst CoP@NF, which includes: A1. Place the nickel foam in an ultrasonic container and sonicate with anhydrous ethanol at 150~200W for 15 minutes to remove organic pollutants. Then sonicate with dilute hydrochloric acid at a mass fraction of 5%~10% for 10 minutes to remove the oxide layer. Finally, sonicate with ethanol for 15 minutes, then sonicate with deionized water for 10 minutes, and rinse with deionized water several times to obtain pretreated nickel foam.
[0051] A2. Dissolve 41.48 mg of cobalt nitrate hexahydrate and 0.15 g of sodium hypophosphite in deionized water to prepare a mixed impregnation solution containing cobalt and phosphorus sources; immerse the pretreated nickel foam in the mixed impregnation solution and let it stand at room temperature for 9 hours to allow the cobalt and phosphorus sources to be adsorbed onto the surface of the nickel foam. A3. Remove the impregnated nickel foam and dry it to fix the loaded cobalt and phosphorus sources onto the surface of the nickel foam in crystal form. A4. Place the dried nickel foam substrate in a container and heat it to 350~400℃ at a rate of 2-5 min℃ / min under an argon atmosphere. Hold the temperature for 2-4 hours to reduce and phosphate the cobalt source to generate a cobalt phosphide active layer on the surface of the nickel foam. A5. After the phosphating reaction is completed, the mixture is cooled to room temperature under an argon atmosphere, washed several times with deionized water, and dried to obtain the cobalt phosphide catalyst, denoted as CoP@NF.
[0052] Comparative Example 2 A method for preparing a cobalt phosphide catalyst, wherein the cobalt phosphide is... ,like Figure 3 The image shows a cobalt phosphide catalyst. A schematic diagram of the preparation process of @NF, which includes: B1. Place the nickel foam in an ultrasonic container and sonicate with anhydrous ethanol at 150~200W for 15 minutes to remove organic pollutants. Then sonicate with dilute hydrochloric acid at a mass fraction of 5%~10% for 10 minutes to remove the oxide layer. Finally, sonicate with ethanol for 15 minutes, then sonicate with deionized water for 10 minutes, and rinse with deionized water several times to obtain pretreated nickel foam.
[0053] B2. Dissolve 41.48 mg of cobalt nitrate hexahydrate and 0.1 g of sodium hypophosphite in deionized water to prepare a mixed impregnation solution containing cobalt and phosphorus sources; immerse the pretreated nickel foam in the mixed impregnation solution and let it stand at room temperature for 9 hours to allow the cobalt and phosphorus sources to be adsorbed onto the surface of the nickel foam. B3. Remove the impregnated nickel foam and dry it to fix the loaded cobalt and phosphorus sources onto the surface of the nickel foam in crystal form. B4. Place the dried nickel foam substrate in a container and heat it to 280~300℃ at a rate of 2-5℃ / min under an argon atmosphere. Hold the temperature for 1-2 hours to reduce and phosphate the cobalt source to generate a cobalt phosphide active layer on the surface of the nickel foam. B5. After the phosphating reaction is complete, the mixture is cooled to room temperature under an argon atmosphere, washed several times with deionized water, and dried to obtain the cobalt phosphide catalyst, denoted as [catalyst name missing]. @NF.
[0054] Catalyst characterization I. XRD Characterization The catalysts prepared in Example 1 and Comparative Examples 1-2 were characterized by XRD, as follows: Figures 4-6 The figures shown are those prepared in Example 1. @NF, CoP@NF prepared in Comparative Example 1, and CoP@NF prepared in Comparative Example 2 XRD pattern of @NF. Figure 4 It is known that the cobalt phosphide heterojunction catalyst prepared in Example 1 @NF, the cobalt phosphide catalyst CoP@NF prepared in Comparative Example 1 only has the characteristic peak of CoP and is a single crystalline phase; the cobalt phosphide catalyst prepared in Comparative Example 2 @NF Only The characteristic peaks indicate a single crystalline phase.
[0055] II. HRTEM Characterization The catalysts prepared in Example 1 and Comparative Examples 1-2 were characterized by HRTEM, as follows: Figures 7-9 The figures shown are those prepared in Example 1. @NF, CoP@NF prepared in Comparative Example 1, and CoP@NF prepared in Comparative Example 2 @NF's HRTEM diagram. According to Figure 7 It can be seen that cobalt phosphide heterojunction catalysts @NF can distinguish different lattice spacings of 0.282 nm (CoP(011)) and 0.220 nm ( (201) directly confirms the coexistence of heterogeneous interfaces. And by Figure 8 It can be seen that the cobalt phosphide catalyst CoP@NF can resolve the (011) crystal plane of CoP with a lattice spacing of 0.282 nm; according to Figure 9 Cobalt phosphide catalyst @NF can distinguish the corresponding lattice spacing of 0.220 nm. The (201) crystal plane.
[0056] Performance testing like Figure 10 The diagram shows a catalytic plastic recycling and hydrogen evolution system, the electrolysis system including: An electrolytic cell, wherein the electrolytic cell is divided into an anode chamber and a cathode chamber by a cation exchange membrane, the anode chamber being used to hold the plastic hydrolysate and the cathode chamber being used to hold the potassium hydroxide solution; Anode, which is inserted into the anode chamber; Cathode, the cathode being inserted into the cathode chamber; A reference electrode, inserted into the cathode chamber, is used to monitor the cathode potential; A platinum sheet counter electrode is inserted into the cathode chamber to assist the cathode reaction; An electrochemical workstation is connected to the anode electrode, the reference electrode, and the platinum sheet counter electrode, respectively.
[0057] The cobalt phosphide heterojunction catalyst prepared in Example 1 @NF and carrier NF are used in the anode of electrolytic cells for the oxidation of hydrolysate from waste plastics. Figure 10 The electrocatalytic plastic recycling and hydrogen evolution system shown uses the cobalt phosphide heterojunction catalyst prepared in Example 1. Using NF and catalyst support NF as the anode electrode and a platinum sheet electrode as the cathode electrode, the LSV spectra of the oxidation of waste plastic hydrolysate were measured with different anode electrodes. The results are as follows: Figure 11As shown.
[0058] Depend on Figure 11 It can be seen that the cobalt phosphide heterojunction catalyst prepared in Example 1 @NF has a low onset potential and a high current density, indicating that @NF exhibits high catalytic activity towards the hydrolysate of waste plastics. Compared with the control group (carrier NF), this demonstrates... @NF's high catalytic activity comes from the cobalt phosphide heterojunction. The existence of.
[0059] Figure 12 The cobalt phosphide heterojunction catalyst prepared in Example 1 @NF and the catalyst CoP@NF prepared in Comparative Examples 1 and 2, @NF LSV spectrum of oxidation of waste plastic hydrolysate at the anode of an electrolytic cell.
[0060] use Figure 10 The electrocatalytic plastic recycling and hydrogen evolution system shown uses the cobalt phosphide heterojunction catalyst prepared in Example 1. @NF and the catalyst CoP@NF prepared in Comparative Examples 1 and 2, @NF was used as the anode electrode, and a platinum sheet electrode was used as the cathode electrode. The LSV spectra of different anode electrodes for the oxidation of waste plastic hydrolysate were measured. The results are as follows: Figure 12 As shown. By Figure 12 It can be seen that the cobalt phosphide heterojunction catalyst prepared in Example 1 @NF has a low onset potential and a high current density, indicating that @NF exhibits high catalytic activity for the hydrolysis of waste plastics. Compared with the control group single-phase catalyst (CoP@NF, ... Compared to @NF, this confirms The high catalytic activity of @NF stems from the presence of the heterojunction. The heterojunction interface induces a downward shift of the d-band center, optimizing the adsorption energy of plastic-derived intermediates and enhancing PET conversion.
[0061] Figure 13 The cobalt phosphide heterojunction catalyst prepared in Example 1 LSV spectra of @NF and the support NF at the cathode of the electrolytic cell for hydrogen evolution in potassium hydroxide solution.
[0062] use Figure 10 The electrocatalytic plastic recycling and hydrogen evolution system shown uses the cobalt phosphide heterojunction catalyst prepared in Example 1. Using @NF and the carrier NF as cathode electrodes and a platinum sheet electrode as the anode electrode, the LSV spectra of hydrogen evolution from potassium hydroxide solution were measured for different cathode electrodes. The results are as follows: Figure 13As shown. By Figure 13 It can be seen that the cobalt phosphide heterojunction catalyst prepared in Example 1 @NF has a low onset potential and a high current density, indicating that @NF exhibits high catalytic activity for hydrogen evolution from potassium hydroxide solution. This further confirms, compared to the control group supported by NF, that... @NF's high catalytic activity comes from the cobalt phosphide heterojunction. The existence of.
[0063] Figure 14 The cobalt phosphide heterojunction catalyst prepared in the examples @NF and the catalyst CoP@NF prepared in Comparative Examples 1 and 2, @NF LSV spectrum of hydrogen evolution in potassium hydroxide solution at the cathode of an electrolytic cell.
[0064] use Figure 10 The electrocatalytic plastic recycling and hydrogen evolution system shown uses the cobalt phosphide heterojunction catalyst prepared in Example 1. @NF and the catalyst CoP@NF prepared in Comparative Examples 1 and 2, @NF was used as the cathode electrode, and a platinum sheet electrode was used as the anode electrode. The LSV spectra of hydrogen evolution from potassium hydroxide solution were measured using different cathode electrodes. The results are as follows: Figure 14 As shown. By Figure 14 It can be seen that the cobalt phosphide heterojunction catalyst prepared in Example 1 @NF has a low onset potential and a high current density, indicating that @NF exhibits high catalytic activity for hydrogen evolution from potassium hydroxide solution. Compared to the control group single-phase catalyst (CoP@NF, ... Compared to @NF, this confirms The high catalytic activity of @NF stems from the presence of the heterojunction. The heterojunction interface induces a downward shift of the d-band center, optimizing the hydrogen adsorption free energy and enhancing the hydrogen evolution reaction. Figures 11-14 This indicates that the cobalt phosphide heterojunction catalyst prepared in Example 1... @NF is a bifunctional catalyst that exhibits high catalytic activity for both the oxidation of hydrolysate from waste plastics at the anode and the hydrogen evolution from potassium hydroxide solution at the cathode.
[0065] Figure 15 The cobalt phosphide heterojunction catalyst prepared in Example 1 When @NF is used as both an anode and cathode electrode in an electrochemical recovery system coupled with a cathode hydrogen evolution, the Faraday efficiency (FE) and selectivity of formic acid, the electrochemical conversion product of the anode plastic hydrolysate, at different potentials are analyzed.
[0066] Figure 16The cobalt phosphide heterojunction catalyst prepared in Example 1 When @NF is used as both an anode and cathode electrode in an electrochemical recovery system coupled with a cathode hydrogen evolution, the Faraday efficiency (FE) and selectivity of formic acid, the electrochemical conversion product of the anode plastic hydrolysate, are observed when different charges pass through it.
[0067] use Figure 10 The electrocatalytic plastic recycling and hydrogen evolution system shown uses the cobalt phosphide heterojunction catalyst prepared in Example 1. Using @NF as the cathode and anode electrodes respectively, the Faradaic efficiency (FE) and selectivity of formic acid, the electrochemical conversion product of the hydrolysate of waste plastic at the anode, were tested at different potentials and at the same potential with different charges. The results are as follows: Figure 15 and Figure 16 As shown.
[0068] Depend on Figure 15 and Figure 16 It can be seen that at the optimized potential of 1.45 V ( Figure 15 This catalyst simultaneously achieved a formic acid Faradaic efficiency of 89.3% and a selectivity of 93.3%, significantly outperforming most reported systems. Crucially, even under long-term electrolysis conditions (… Figure 16 It can also maintain a Faraday efficiency of over 83% and a selectivity of over 90% at a charge of 300 C, with a peak selectivity of 99.2% at 300 C. This superior performance stability and product specificity stem from... The heterojunction phase offers advantages because its customized electronic structure facilitates the selective breaking of C-C bonds in ethylene glycol (a major product of PET hydrolysis) to form formate, while simultaneously suppressing over-oxidation to carbon dioxide. These results collectively validate the cobalt phosphide heterojunction catalyst prepared in Example 1. @NF can be used as a highly efficient and selective bifunctional catalyst in electrocatalytic plastic recycling and hydrogen evolution systems. It has excellent electrocatalytic performance for both anodic oxidation and cathodic hydrogen evolution of plastics, thereby enabling the electrochemical recycling products of plastics to have high selectivity and Faraday efficiency, which helps to improve the overall current efficiency of the system.
[0069] To clarify the cobalt phosphide heterojunction catalyst observed in the experiment The superior bifunctional activity exhibited by @NF ( Figures 11-16 To understand the fundamental origin of this process, DFT calculations were performed in the embodiments of this disclosure, revealing the crucial role of the interface structure at the atomic level. Calculations of the adsorption energy (Eads) for the key intermediate CHO-CHO in ethylene glycol oxidation (EGOR, a PET hydrolysis product) show that key optimizations were achieved at the heterojunction interface. Figure 17(See Figure b). *The adsorption energy of CHO-CHO on CoP(011) is too weak (Eads = -0.24 eV), while... The adsorption energy on (201) is too strong (Eads = -0.82 eV), while the Eads on the heterojunction surface is close to the optimal value of -0.11 eV. This is beneficial for the adsorption of intermediates and the desorption of subsequent products, perfectly matching the enhanced anodic performance. This interface tuning is directly related to the change in electronic structure. PDOS analysis ( Figure 17 The results showed that the d-band center (εd) of Co atoms at the heterojunction interface was significantly shifted (εd = -1.186 eV), compared to the single-phase (CoP: εd = -1.295 eV). Compared to (εd = -1.123 eV), the upward shift of εd relative to CoP in the heterojunction enhances intermediate adsorption, while relative to... The placement of the heterojunction prevents excessive bonding, embodying the Sabatil principle. Crucially, the heterojunction also significantly enhances the kinetics of the hydrogen evolution reaction. The free energy change (ΔGH*) of the hydrogen adsorption step calculated above. Figure 17 The difference between f (|ΔGH*| = 0.11 eV) and CoP (|ΔGH*| = 0.28 eV) is greater than that between f (|ΔGH*| = 0.11 eV) and CoP (|ΔGH*| = 0.28 eV). The value (|ΔGH*| = 0.52 eV) is closer to the thermally neutral ideal (0 eV), which is consistent with the lower hydrogen evolution overpotential observed in the experiment. This optimized electronic structure and the origin of charge transfer were visualized through charge density difference analysis. Figure 17 (g). Significant charge redistribution occurred at the interface (yellow: accumulation, cyan: depletion), creating an intrinsic electric field that facilitated the transfer of charge from CoP to... Effective electron transfer within the region, this interfacial charge transfer not only modulates the d-band center and adsorption strength, but may also expose more electrochemically active sites at the phase boundary. Based on DFT results, this indicates... The interfacial synergy within the heterojunction optimizes electronic properties, enhances charge transfer kinetics, and modulates adsorption energy. These are the fundamental driving factors behind its superior bifunctional activity in the conversion of PET hydrolysis products to formate and hydrogen evolution. This synergistic effect is unattainable by any single phosphating phase. Figures 11-16 The experimental results are consistent with those in the study.
[0070] It should be understood that the various forms of processes shown above can be used to rearrange, add, or delete steps. For example, the steps described in this disclosure can be executed in parallel, sequentially, or in different orders, as long as the desired result of the technical solution disclosed in this disclosure can be achieved, and this is not limited herein.
[0071] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one of that feature. In the description of this disclosure, "a plurality of" means two or more, unless otherwise explicitly specified.
[0072] The above description is merely a specific embodiment of this disclosure, but the scope of protection of this disclosure is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in this disclosure should be included within the scope of protection of this disclosure. Therefore, the scope of protection of this disclosure should be determined by the scope of the claims.
Claims
1. A method for preparing a cobalt phosphide heterojunction catalyst, characterized by, The method comprises: pretreating a three-dimensional porous conductive substrate to remove organic contaminants and oxide layers on the surface of the three-dimensional porous conductive substrate; preparing a mixed impregnation solution containing a cobalt source and a phosphorus source; immersing the pretreated three-dimensional porous conductive substrate in the mixed impregnation solution, and standing at room temperature for 6-12 hours to load the cobalt source and the phosphorus source on the surface of the three-dimensional porous conductive substrate; taking out the impregnated three-dimensional porous conductive substrate and drying to fix the loaded cobalt source and phosphorus source in the form of crystals on the surface of the three-dimensional porous conductive substrate; placing the dried three-dimensional porous conductive substrate in a container, heating to 300-350 DEG C under an inert atmosphere, and keeping warm for 1-2 hours to reduce phosphorize the cobalt source and generate a cobalt phosphide heterojunction active layer on the surface of the substrate; after the phosphorization reaction is completed, cooling under the protection of an inert atmosphere, and cleaning to remove impurities to obtain a cobalt phosphide heterojunction catalyst.
2. The method for preparing the cobalt phosphide heterojunction catalyst according to claim 1, characterized in that, The pretreated three-dimensional porous conductive substrate comprises: ultrasonically cleaning the three-dimensional porous conductive substrate in organic cleaning agent, acidic cleaning agent, polar solvent and deionized water in sequence to remove organic contaminants and oxide layers on the surface of the three-dimensional porous conductive substrate.
3. The method for preparing the cobalt phosphide heterojunction catalyst according to claim 1, characterized in that, In the mixed impregnation solution, the molar ratio of the cobalt source to the phosphorus source is 1:10-1:
20.
4. The method of claim 1, wherein the cobalt phosphide heterojunction catalyst is prepared by the steps of: The three-dimensional porous conductive substrate is any one of foamed metal, porous carbon material or porous ceramic conductive material; the foamed metal is any one of foamed nickel, foamed copper or foamed iron.
5. The method of claim 1, wherein the cobalt phosphide heterojunction catalyst is prepared by the steps of: The cobalt source is any one or mixture of multiple of nitrate, chloride, sulfate or carboxylate of cobalt; and the phosphorus source is hypophosphite.
6. The preparation method of the cobalt phosphide heterojunction catalyst according to claim 1, characterized in that The cobalt phosphide heterojunction is The heterojunction is The heterojunction is supported on a surface of a three-dimensional porous conductive substrate.
7. The method of claim 6, wherein the cobalt phosphide heterojunction catalyst is prepared by the steps of: placing the dried three-dimensional porous conductive substrate in a container, heating to 300-350 DEG C under an inert atmosphere, and keeping warm for 1-2 hours comprises: The phosphating process is controlled by temperature in sections, first, the temperature is raised to 250-280°C at a rate of 2-3°C / min, and the temperature is kept for 0.5-1 hour, so that the phosphorus source is slowly decomposed and reacts with the cobalt source to generate intermediate; then, the temperature is raised to 320-350°C at a rate of 3-5°C / min, and the temperature is kept for 1-1.5 hours, so that the intermediate is further phosphated to generate heterojunction. heterojunction.
8. A cobalt phosphide heterojunction catalyst characterized by, prepared according to any one of the preparation methods of claims 1-7.
9. Use of a cobalt phosphide heterojunction catalyst prepared according to the method of any one of claims 1-7 in electrocatalytic plastic recycling and hydrogen evolution. The cobalt phosphide heterojunction catalyst is used as an anode electrode and / or a cathode electrode of an electrolysis system.
10. Use according to claim 9, characterized in that, The electrocatalytic plastic recycling and hydrogen evolution reaction are carried out in an alkaline electrolyte.