A cobalt phosphide supported Ru monatomic catalyst, a preparation method and application thereof

Abstract

The application belongs to the field of catalyst materials and electrochemistry, and particularly relates to a cobalt phosphide supported Ru monatomic catalyst and a preparation method and application thereof. By introducing 1,10-phenanthroline and urea as a regulator and combining with a joule heat treatment technology, high loading, high dispersion and strong anchoring of Ru monatomic atoms on the cobalt phosphide carrier are realized. The core lies in that the monatomic atom agglomeration is inhibited by molecular modification and rapid heat activation, and the metal-carrier interaction is enhanced, so that the atomic dispersion is improved, and the active site density is significantly increased. The prepared catalyst has rich defect structure and excellent conductivity, can provide a large number of uniform active centers for electrocatalytic reaction, and promotes charge transmission. In OER, the catalyst shows high activity and stability, and the performance advantage is derived from the electronic synergistic effect between the high loading monatomic atom and the carrier, and the optimized adsorption capacity of the defect site to the reaction intermediate.

Description

Technical Field

[0001] This invention belongs to the field of catalyst materials and electrochemical technology, specifically relating to a cobalt phosphide-supported Ru single-atom catalyst, its preparation method, and its application. Background Technology

[0002] Breakthroughs in water splitting for hydrogen production are crucial to achieving the strategic goal of carbon neutrality, and the efficiency of the oxygen evolution reaction (OER), a key half-reaction, directly determines the energy consumption and economic viability of the overall system. However, the OER involves a complex four-electron transfer process with slow reaction kinetics and requires high overpotential drive, which severely restricts the industrial application of water electrolysis technology.

[0003] In recent years, transition metal-based catalysts (such as oxides, hydroxides, and phosphides) have attracted widespread attention due to their tunable electronic structures and abundant active sites. Among them, single-atom catalysts (SACs) have shown great potential due to their extremely high atom utilization and excellent catalytic performance. However, traditional synthesis methods face two key challenges in preparing single-atom catalysts: First, noble metals (such as Ru and Pt) have high surface free energies and tend to migrate and aggregate to form nanoparticles rather than single-atom states; second, conventional impregnation and calcination methods are difficult to accurately construct sufficient anchoring sites (such as P vacancies and Co defects) on the surface of the support (such as cobalt phosphide), and cannot provide strong metal-support interaction (SMSI) to stabilize single atoms.

[0004] Ru-based single-atom catalysts not only significantly reduce the amount of precious metals used and lower costs, but also significantly enhance OER activity by optimizing the coordination environment of active sites. Anchoring Ru single atoms to the surface of transition metal phosphides (such as CoP) forms a "single-atom-support" synergistic interface, which can stabilize single atoms to prevent aggregation and optimize the reaction energy barrier through electronic regulation, thereby improving OER activity and durability. However, traditional synthesis methods such as impregnation often result in low single-atom loading, poor dispersion, and limited catalytic performance due to insufficient anchoring sites on the support. To address these shortcomings, a method combining in-situ synthesis and Joule heat treatment was developed to prepare phosphide-supported metal single-atom catalysts, effectively solving the problems of poor single-atom dispersion and limited catalytic performance in traditional methods.

[0005] Chinese invention patent document CN113249739A discloses a method for preparing a noble metal single-atom catalyst anchored by anion vacancies of transition metal phosphide. This method first uses a mixed solution of transition metal salt, urea, ammonium fluoride, and a support for hydrothermal treatment to obtain a precursor, then performs high-temperature phosphating to obtain a transition metal phosphide, followed by high-temperature heat treatment under a reducing atmosphere, and finally obtains the metal phosphide-supported single-atom catalyst by impregnation. This method is cumbersome, requires multiple heat treatment steps, and has high energy consumption. Furthermore, the single-atom Ru loading depends solely on the surface P vacancies, and the loading rate is strictly limited by the concentration of P vacancies, resulting in a low loading of only 1.5%. Therefore, developing efficient, stable, and low-cost novel OER catalysts has become a current research focus. Summary of the Invention

[0006] To address the problems existing in the prior art, this invention provides a CoP-supported Ru single-atom catalyst, its preparation method, and its application.

[0007] This invention is specifically achieved through the following technical solutions: The first aspect of this invention provides a method for preparing a cobalt phosphide-supported Ru single-atom catalyst, comprising the following steps: S.1 Cobalt nitrate hexahydrate, ruthenium trichloride, urea, and 1,10-phenanthroline were added to methanol and sonicated to obtain a first mixture; 2-methylimidazole was added to methanol and sonicated to obtain a second mixture. S.2 After the first mixed solution and the second mixed solution are mixed evenly, the mixture is subjected to ultrasonic reaction at room temperature, and then centrifuged and vacuum dried to obtain a solid precursor; S.3 The solid precursor was ground into powder, and then the precursor powder and sodium dihydrogen phosphate solid were placed in the graphite sample stage groove of the Joule heating device. Joule heat treatment was then carried out under the protective atmosphere of nitrogen to obtain the CoP supported Ru single-atom catalyst.

[0008] Further, in step S.1, the ratio of cobalt nitrate hexahydrate, ruthenium trichloride, urea, 1,10-phenanthroline, and methanol in the mixed solution is: 3 mmol: 1-2 mmol: 4-8 mmol: 2-4 mmol: 20-60 mL; and the ratio of 2-methylimidazole and methanol in the second mixed solution is: 10-13 mmol: 8-20 mL.

[0009] Furthermore, the ultrasound time in step S.1 is 0.1-1h and 5-10min respectively; the ultrasound time in step S.2 is 6-12h.

[0010] Furthermore, in step S.2, the vacuum drying conditions are: drying temperature 60-90℃ and drying time 8-16h.

[0011] Furthermore, in step S.3, the ratio of precursor powder to sodium dihydrogen phosphate is 1.5g: 1-6g.

[0012] Further, in step S.3, the conditions for Joule heat treatment are: heat treatment temperature 600-2000℃, heating rate 1000-3000℃ / s, and 3-10 Joule heat treatments; Joule heat treatment is heating from room temperature to the target temperature and then naturally cooling to room temperature, which is represented as one treatment.

[0013] A second aspect of the present invention provides a CoP-supported Ru single-atom catalyst prepared according to any of the above-described preparation methods.

[0014] A second aspect of the present invention provides the application of the CoP-supported Ru single-atom catalyst described above in OER catalytic reactions under alkaline conditions.

[0015] The beneficial effects of this invention are as follows: (1) Compared with traditional tube furnace technology, the Joule heat treatment technology of the present invention utilizes instantaneous ultra-fast Joule heat for heating and achieves ultra-fast quenching. This "instantaneous-non-equilibrium" heat treatment path can effectively suppress the migration and aggregation of metal atoms at high temperatures, "freezing" the active components in a highly dispersed state. At the same time, this technology can easily create high concentration defects and metastable phases in the material, thereby simultaneously optimizing the activity and stability of the catalyst.

[0016] (2) This invention ingeniously utilizes the complexation effect of urea and metal ions to achieve efficient anchoring of metal single atoms. Simultaneously, thermal decomposition generates ammonia, providing a reducing atmosphere and nitrogen source in the reaction system, thereby effectively inhibiting the aggregation of metal single atoms and ensuring their high dispersion on the support surface. Furthermore, the introduction of 1,10-phenanthroline as an organic ligand, with its nitrogen-containing coordinating group, constructs a stable complex with metal ions, further playing a crucial role in anchoring and stabilizing single atoms. The synergistic effect of urea and 1,10-phenanthroline in the system promotes the uniform anchoring of metal ions within the crystal framework and significantly increases the loading of single atoms, thereby jointly enhancing the catalytic activity and conductivity of the material.

[0017] (3) The CoP-supported Ru single-atom catalyst of the present invention has a single-atom loading of up to 4.72%. Under alkaline conditions, this catalyst exhibits excellent OER performance. At 10 mA·cm⁻¹ -2 At the specified current density, its OER overpotential and stability are 164 mV and 50 hours, respectively, which are significantly lower than the 310 mV overpotential of commercial RuO2 catalysts under the same conditions, demonstrating a significant performance advantage. Therefore, this catalyst has broad prospects for industrial applications. Attached Figure Description

[0018] Figure 1 The image shows the X-ray diffraction (XRD) pattern of the sample from Example 1. Figure 2 This is a high-resolution transmission electron microscope (HRTEM) image of the sample from Example 1; Figure 3 The image shows the electron paramagnetic resonance (EPR) image of the sample from Example 1. Figure 4 The image shows the linear sweep voltammetry (LSV) test result of the sample from Example 1. Figure 5 The chronocurrent curve (it) of the sample in Example 1 is shown. Detailed Implementation

[0019] The technical features and advantages of the invention will be described in more detail below with reference to the accompanying drawings.

[0020] Example 1

[0021] (1) Add 3 mmol Co(NO3)2·6H2O, 1.5 mmol RuCl3, 5 mmol urea and 3 mmol 1,10-phenanthroline to 30 mL of methanol and sonicate for 30 min to obtain the first mixture; add 12 mmol 2-methylimidazole to 10 mL of methanol and sonicate for 8 min to obtain the second mixture. (2) After mixing the first mixed solution and the second mixed solution evenly, the mixture was ultrasonically reacted at room temperature for 9 hours. After centrifugation and washing with methanol, the mixture was vacuum dried at 80°C for 12 hours to obtain the first solid. (3) The first solid was ground into powder, and then 1.5g of the first solid powder and 4g of NaH2PO4 solid were placed in the graphite sample stage groove of the Joule heating device. Then, the Joule heat treatment was performed 5 times in air atmosphere. The Joule heat treatment temperature was 1500℃ and the Joule heat treatment heating rate was 2000℃ / s to obtain the CoP supported Ru single atom catalyst, which was recorded as the sample of Example 1.

[0022] The sample of Example 1 obtained in step (3) was subjected to XRD, HRTEM, EPR and inductively coupled plasma mass spectrometry (ICP). The ICP test results are presented in the form of Ru mass fraction (wt% (Ru)), see below. Figure 1 , Figure 2 , Figure 3 See Table 1.

[0023] according to Figure 1The XRD pattern of the sample in Example 1 showed clear characteristic peaks, which were highly consistent with the standard card PDF#00-029-0497, and no Ru elemental peaks were found, indicating that the sample was mainly composed of the CoP phase. Figure 2 The data shows that the single metal atoms are evenly distributed and exhibit clear crystal stripes, proving that the Ru single atoms are well dispersed on CoP. Figure 3 The EPR signal is significant at g=2.005, indicating the presence of abundant phosphorus vacancies in the sample, thus proving the presence of phosphorus vacancies. According to Table 1, the mass fraction of Ru in the CoP-supported Ru single-atom catalyst can reach 4.72%, indicating that the catalyst has a high loading capacity and can effectively improve catalytic activity and conductivity.

[0024] The Example 1 sample obtained in step (4) is used for OER applications, including the following application steps: 4 mg of the Example 1 sample and 1 mg of commercial carbon black were dispersed in 0.5 mL of an ethanol-Nafion mixed solution (0.48 mL of ethanol and 0.02 mL of 0.5% Nafion solution). After sonication for 2 hours, a uniformly dispersed Example 1 sample mixed solution was obtained. 10 μL of the Example 1 sample mixed solution was dropped onto a glassy carbon electrode and allowed to air dry to obtain a glassy carbon electrode modified with the Example 1 sample. Electrochemical tests were performed on a CHI760E electrochemical workstation. The glassy carbon electrode modified with the Example 1 sample was used as the working electrode, a graphite rod as the counter electrode, saturated calomel as the reference electrode, and 1 M KOH aqueous solution as the electrolyte. The LSV and it tests of the OER were performed, and the test results are shown in the figures below. Figure 4 , Figure 5 See Table 1.

[0025] Depend on Figure 4 It can be seen that at 10mA·cm -2 At the specified current density, the glassy carbon electrode modified with the sample in Example 1 requires only 164 mV overpotential, which is significantly lower than that of commercial RuO2 (310.6 mV @ 10 mA·cm). -2 It has broad prospects for industrial application. From Figure 5 It can be seen that at 10mA·cm -2 After being tested at a current density for 50 hours, the voltage remained almost unchanged, indicating that the sample of Example 1 exhibited excellent stability.

[0026] Example 2 (1) Add 1 mmol Co(NO3)2·6H2O, 1 mmol RuCl3, 4 mmol urea and 2 mmol 1,10-phenanthroline to 20 mL of methanol and sonicate for 30 min to obtain the first mixture; add 10 mmol 2-methylimidazole to 8 mL of methanol and sonicate for 8 min to obtain the second mixture. (2) After mixing the first mixed solution and the second mixed solution evenly, the mixture was ultrasonically reacted at room temperature for 6 hours. After centrifugation and washing with methanol, the mixture was vacuum dried at 60°C for 16 hours to obtain the first solid. (3) Grind the first solid into powder, and then place 1.5g of the first solid powder and 1g of NaH2PO4 solid in the graphite sample stage groove of the Joule heating device. Then perform Joule heat treatment 3 times in air atmosphere. The Joule heat treatment temperature is 2000℃ and the Joule heat treatment heating rate is 3000℃ / s to obtain cobalt phosphide supported Ru single atom catalyst, which is recorded as the sample of Example 2.

[0027] The ICP test was performed on the sample of Example 2 obtained in step (3), and the test results are presented in the form of Ru mass fraction (wt% (Ru)), as shown in Table 1.

[0028] As shown in Table 1, the mass fraction of Ru atoms in the sample of Example 2 can reach 4.38%, indicating that the loading of single atoms in the material is relatively high.

[0029] The sample of Example 2 obtained in step (3) was used for OER application. The test steps and test methods were the same as those of Example 1. The test results are shown in Table 1.

[0030] Table 1 shows that at 10 mA·cm -2 At the specified current density, the glassy carbon electrode modified in Example 2 requires only 225 mV overpotential, far lower than that of commercial RuO2 (310.6 mV @ 10 mA·cm). -2 It has broad prospects for industrial application. Example

[0031] (1) Add 1 mmol Co(NO3)2·6H2O, 2 mmol RuCl3, 8 mmol urea and 4 mmol 1,10-phenanthroline to 60 mL of methanol and sonicate for 30 min to obtain the first mixture; add 13 mmol 2-methylimidazole to 20 mL of methanol and sonicate for 8 min to obtain the second mixture. (2) After mixing the first mixed solution and the second mixed solution evenly, the mixture was ultrasonically reacted at room temperature for 12 hours. After centrifugation and washing with methanol, the mixture was vacuum dried at 90°C for 8 hours to obtain the first solid. (3) Grind the first solid into powder, and then place 1.5g of the first solid powder and 6g of sodium dihydrogen phosphate solid in the graphite sample stage groove of the Joule heating device. Then perform Joule heat treatment 10 times in air atmosphere. The Joule heat treatment temperature is 600℃ and the Joule heat treatment heating rate is 1000℃ / s to obtain cobalt phosphide supported Ru single atom catalyst, which is recorded as the sample of Example 3.

[0032] The ICP test was performed on the sample of Example 3 obtained in step (3), and the test results are presented in the form of Ru mass fraction (wt% (Ru)), as shown in Table 1.

[0033] As shown in Table 1, the mass fraction of Ru atoms in the sample of Example 3 can reach 4.46%, indicating that the loading of single atoms in the material is relatively high.

[0034] The sample of Example 3 obtained in step (3) was used for OER application. The test steps and test methods were the same as those of Example 1. The test results are shown in Table 1.

[0035] Table 1 shows that at 10 mA·cm -2 At the specified current density, the glassy carbon electrode modified in Example 3 required only 196 mV overpotential, far lower than that of commercial RuO2 (310.6 mV @ 10 mA·cm). -2 It has broad prospects for industrial application.

[0036] Comparative Example 1 The difference between Comparative Example 1 and Example 1 is that RuCl3 was not added in step (1), while the rest remained the same.

[0037] The comparative example 1 sample obtained in step (3) was subjected to XRD and EPR tests. The XRD test results are presented in the form of phase composition, as shown in Table 1 and 2. Figure 3 (EPR).

[0038] According to Table 1, the sample of Comparative Example 1 is mainly composed of the CoP phase. Figure 3 The EPR signal intensity at g=2.005 was weaker than that in Example 1, indicating that the phosphorus vacancy content in Comparative Example 1 was lower than that in Example 1. This is because Ru, as an electron acceptor, attracts electrons from the CoP carrier, thereby weakening the adjacent Co-P bond and reducing the formation energy of phosphorus vacancies.

[0039] The Comparative Example 1 sample obtained in step (3) was used for OER application. The test steps and test methods were the same as in Example 1. The test results are shown in Table 1.

[0040] According to Table 1, at 10 mA·cm -2At the specified current density, the glassy carbon electrode modified with the sample in Comparative Example 1 required an overpotential of 320 mV. This is due to the lack of optimization of the electronic structure of the support by Ru. Although Ru itself is a highly efficient OER active center, it failed to effectively reduce the reaction energy barrier, thus leading to a decrease in OER performance.

[0041] Comparative Example 2 The difference between Comparative Example 2 and Example 1 is that 1,10-phenanthroline was not added in step (1), while the rest remained the same.

[0042] The comparative example 2 sample obtained in step (3) was subjected to XRD, EPR and ICP tests. The XRD and ICP test results are presented in the form of phase composition and Ru mass fraction (wt% (Ru)), as shown in Table 1 and Figure 3 (EPR).

[0043] According to Table 1, the sample of Comparative Example 2 consists of elemental phases of CoP and Ru. Figure 3 The EPR signal intensity at g=2.005 was weaker than that in Example 1, indicating that the phosphorus vacancy content in Comparative Example 2 was lower than that in Example 1. Table 1 also shows that the mass fraction of Ru in Comparative Example 2 was 3.09%, indicating a decrease in its loading. This is because the presence of 1,10-phenanthroline allows it to preferentially coordinate with Ru ions, forming a stable complex. 1,10-phenanthroline itself has a large planar rigid structure, and the steric hindrance effect effectively prevents Ru ions from approaching, thereby inhibiting the formation of Ru clusters or nanoparticles. In addition, in the early stage of pyrolysis, the carbon skeleton of 1,10-phenanthroline forms a temporary "carbon cage" structure, which effectively restricts the migration of Ru atoms and stabilizes Ru atoms at high temperatures, thus achieving excellent atomic-level dispersion of Ru atoms. Without the presence of 1,10-phenanthroline, Ru atoms would migrate and aggregate to form Ru cluster nanoparticles, leading to a corresponding increase in their content.

[0044] The comparative sample 2 obtained in step (3) was used for OER application. The test steps and test methods were the same as in Example 1. The test results are shown in Table 1.

[0045] According to Table 1, at 10 mA·cm -2 At the specified current density, the glassy carbon electrode modified with the sample in Comparative Example 2 required an overpotential of 280 mV. This indicates that the absence of 1,10-phenanthroline led to the formation of Ru nanoclusters rather than Ru single atoms, thus affecting the catalytic performance of the material. Simultaneously, the decomposition and escape of 1,10-phenanthroline at high temperatures introduced more local lattice strain and defects into the CoP lattice. These defects facilitated the efficient adsorption of reaction intermediates, thereby enhancing catalytic activity.

[0046] Comparative Example 3 The difference between Comparative Example 3 and Example 1 is that no urea was added in step (1), while everything else remained the same.

[0047] The comparative example 3 sample obtained in step (3) was subjected to XRD, EPR and ICP tests. The XRD and ICP test results are presented in the form of phase composition and Ru mass fraction (wt% (Ru)), as shown in Table 1 and Figure 3 (EPR).

[0048] According to Table 1, the sample of Comparative Example 3 is mainly composed of elemental phases of CoP and Ru. Figure 3 The EPR signal intensity at g=2.005 was lower than that of Example 1, indicating that the phosphorus vacancy content in Comparative Example 3 was lower than that in Example 1. Table 1 also shows that the mass fraction of Ru atoms in Comparative Example 3 was only 1.56%, indicating a very low Ru loading in the material. This phenomenon can be attributed to urea participating in the formation of the ZIF-67 framework, acting as a carrier for CoP and Ru single atoms. Furthermore, the urea molecule has carbonyl O and -NH2 groups, which can coordinate with Ru ions, inhibiting aggregation during reduction and contributing to the formation of an atomically dispersed state. Simultaneously, during thermal decomposition, the ammonia gas produced by urea creates a reducing atmosphere, which helps form electron-rich carriers and provides anchoring sites. This atmosphere can also etch phosphorus species, inducing Co-P bond breaking, thereby promoting the generation of phosphorus vacancies. In addition, the synergistic effect of ammonia gas and 1,10-phenanthroline prevents Ru ions from agglomerating during synthesis, which is key to achieving Ru single-atom-level dispersion.

[0049] The comparative sample 3 obtained in step (3) was used for OER application. The test steps and test methods were the same as in Example 1. The test results are shown in Table 1.

[0050] According to Table 1, at 10 mA·cm -2 At the specified current density, the glassy carbon electrode modified with the sample in Comparative Example 3 required an overpotential of 290 mV. This indicates that the absence of urea resulted in a decrease in the Ru single-atom loading and a reduction in the phosphorus vacancy content. Since Ru single atoms serve as active centers and phosphorus vacancies as highly active sites, the reduction of both leads to a decrease in the intrinsic catalytic activity of the catalyst.

[0051] Comparative Example 4 The difference between Comparative Example 4 and Example 1 lies in the heating device and heating conditions in step (3), while the other steps remain the same. The specific operation is as follows: The first solid was ground into powder, and then 1.5g of the first solid powder and 4g of NaH2PO4 solid were placed in a tube furnace. The mixture was then calcined under a nitrogen protective atmosphere at a temperature of 800℃, a heating rate of 10℃ / min, and a holding time of 5h to obtain a cobalt phosphide-supported Ru single-atom catalyst, which was designated as Comparative Example 4.

[0052] The comparative example 4 sample obtained in step (3) was subjected to XRD, EPR and ICP tests. The XRD and ICP test results are presented in the form of phase composition and Ru mass fraction (wt% (Ru)), as shown in Table 1 and Figure 3 (EPR).

[0053] According to Table 1, the sample of Comparative Example 4 is mainly composed of elemental phases of CoP and Ru. Figure 3 The EPR signal intensity at g=2.005 was lower than that of Example 1, indicating that the phosphorus vacancy content in Comparative Example 4 was lower than that in Example 1. Table 1 also shows that the mass fraction of Ru atoms in Comparative Example 4 was 4.74%, indicating that the Ru loading in the material was consistent with that in Example 1, but it did not exhibit atomic dispersion. This is because the calcination process in a conventional tube furnace is relatively slow, and the heating and cooling processes are relatively stable. In this mild thermal environment, the reduced Ru atoms have sufficient time and kinetic energy to migrate to the surface and collide with each other to form clusters or nanoparticles, resulting in a significant decrease in dispersion of Ru, although the Ru loading does not change much. In addition, some of the phosphorus vacancies formed at high temperature may undergo annealing healing or be filled by other atoms during the subsequent slow cooling process, thereby significantly reducing the phosphorus vacancy concentration in the final material.

[0054] The comparative sample 4 obtained in step (3) was used for OER application. The test steps and test methods were the same as in Example 1. The test results are shown in Table 1.

[0055] According to Table 1, at 10 mA·cm -2 At the specified current density, the glassy carbon electrode modified with Comparative Example 4 required an overpotential of 330 mV. This indicates that using a tube furnace and heating device affects the loading of single atoms, typically leading to sintering and pore structure collapse of the catalyst during high-temperature treatment. This structural degradation not only restricts the formation of internal defects, lattice strain, and hierarchical pore structures in the material but also hinders the effective mass transfer between reactants and products, resulting in the blockage of some active sites and significantly reducing the catalytic efficiency of OER. Therefore, the material treated with a Joule heating device exhibits superior performance.

[0056] Table 1. XRD, OER performance, and ICP test results of Examples 1-3 and Comparative Examples 1-4 .

[0057] Comparative Example 1 and Examples 1-3 demonstrate that the introduction of RuCl3 is key to improving the OER performance of the CoP catalyst. Ru not only serves as a highly efficient active center but also significantly modulates the electronic structure of the CoP support, enhancing intrinsic activity. Furthermore, Ru incorporation into the CoP lattice weakens the Co-P bond, reducing the formation energy of phosphorus vacancies. Ru single atoms significantly improve the OER performance of the catalyst by directly acting as active centers and indirectly regulating the electronic structure and defect density of the support. Comparative Example 2 and Examples 1-3 show that 1,10-phenanthroline can form stable complexes with Ru ions, achieving molecular-level dispersion and stability of Ru species in solution, preventing migration and aggregation. Simultaneously, 1,10-phenanthroline provides steric hindrance, ensuring that Ru atoms remain atomically dispersed during assembly with the ZIF-67 precursor, thereby achieving the formation of high-load Ru single atoms. Comparative Example 3 and Examples 1-3 show that urea forms a coordination and anchoring effect with Ru ions in the initial stage, inducing Ru to exhibit an atomically dispersed state. Furthermore, the reducing gases generated during Joule thermal shock pyrolysis, such as NH3, help break Co-P bonds and promote the formation of phosphorus vacancies. Simultaneously, urea synergistically works with 1,10-phenanthroline to ensure uniform anchoring of metal ions within the crystal framework and significantly increase the loading of single atoms. Comparative Example 4 and Examples 1-3 demonstrate that Joule heating technology, replacing traditional tubular furnace calcination, is the decisive process for achieving the special microstructure of the catalyst. Its ultra-fast heating and cooling rates prevent Ru species from migrating and agglomerating on the surface after reduction, instead instantly "freezing" them in situ, thus maintaining a high degree of dispersion of single atoms.

[0058] The above embodiments are intended to illustrate the essential content of the present invention, but are not intended to limit the scope of protection of the present invention. Those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the essence and scope of protection of the present invention.

Claims

1. A method for preparing a cobalt phosphide-supported Ru single-atom catalyst, characterized in that, Includes the following steps: S.1 Cobalt nitrate hexahydrate, ruthenium trichloride, urea, and 1,10-phenanthroline were added to methanol and sonicated to obtain a first mixture; 2-methylimidazole was added to methanol and sonicated to obtain a second mixture. S.2 After the first mixed solution and the second mixed solution are mixed evenly, the mixture is subjected to ultrasonic reaction at room temperature, and then centrifuged and vacuum dried to obtain a solid precursor; S.3 The solid precursor was ground into powder, and then the precursor powder and sodium dihydrogen phosphate solid were placed in the graphite sample stage groove of the Joule heating device. Joule heat treatment was then carried out under the protective atmosphere of nitrogen to obtain the CoP supported Ru single-atom catalyst.

2. The method for preparing a cobalt phosphide-supported Ru single-atom catalyst as described in claim 1, characterized in that, In step S.1, the ratio of cobalt nitrate hexahydrate, ruthenium trichloride, urea, 1,10-phenanthroline, and methanol in the mixed solution is 3 mmol: 1-2 mmol: 4-8 mmol: 2-4 mmol: 20-60 mL; the ratio of 2-methylimidazole and methanol in the second mixed solution is 10-13 mmol: 8-20 mL.

3. The method for preparing a cobalt phosphide-supported Ru single-atom catalyst as described in claim 1, characterized in that, In step S.1, the ultrasound time is 0.1-1h and 5-10min respectively; in step S.2, the ultrasound time is 6-12h.

4. The method for preparing a cobalt phosphide-supported Ru single-atom catalyst as described in claim 1, characterized in that, In step S.2, the vacuum drying conditions are: drying temperature 60-90℃ and drying time 8-16h.

5. The method for preparing a cobalt phosphide-supported Ru single-atom catalyst as described in claim 1, characterized in that, In step S.3, the ratio of precursor powder to sodium dihydrogen phosphate is 1.5g: 1-6g.

6. The method for preparing a cobalt phosphide-supported Ru single-atom catalyst as described in claim 1, characterized in that, In step S.3, the conditions for Joule heat treatment are: heat treatment temperature 600-2000℃, heating rate 1000-3000℃ / s, and 3-10 Joule heat treatments; Joule heat treatment is heating from room temperature to the target temperature and then naturally cooling to room temperature, which is represented as one cycle.

7. The CoP-supported Ru single-atom catalyst prepared by any one of the preparation methods according to claims 1-6.

8. The application of the CoP-supported Ru single-atom catalyst according to claim 7 in OER catalytic reaction under alkaline conditions.

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