A p-block element strengthened double-atomic catalyst, and a preparation method and application thereof

Abstract

The application discloses a P-region element reinforced double-atomic catalyst, a preparation method and application thereof, and belongs to the field of catalysts, and solves the problem of poor selectivity of hydrogen peroxide produced by traditional single-atomic catalysts based on transition metals in electrocatalytic two-electron oxygen reduction. In the application, cobalt and gallium elements are introduced into a zeolite imidazolate precursor by an ion exchange method, the coordination environment of the catalyst is regulated by introducing a sulfur species, and finally, the P-region element reinforced double-atomic catalyst is synthesized by high-temperature annealing. The application also discloses application of the catalyst in electrocatalytic two-electron oxygen reduction. The catalyst has the advantages of high hydrogen peroxide selectivity and high hydrogen peroxide production rate when used in electrocatalytic two-electron oxygen reduction, which has far-reaching significance for expanding the application scenarios of the P-region element catalyst in the field of electrocatalysis.

Description

Technical Field

[0001] This invention belongs to the field of electrocatalytic hydrogen peroxide production technology, specifically relating to a p-block element-enhanced dual single-atom catalyst, its preparation method, and its application as a catalyst for electrocatalytic hydrogen peroxide production. Background Technology

[0002] Hydrogen peroxide (H2O2), as a green oxidant, has wide applications in medical, textile, and environmental catalysis fields. Currently, the synthesis of high-concentration (>37%) H2O2 mainly employs the highly polluting anthraquinone process, which suffers from drawbacks such as high energy consumption, complex processes, and significant transportation risks. Therefore, more economical and environmentally friendly production strategies are expected to meet the growing demand for H2O2. Among the many reported technologies, electrocatalytic two-electron oxygen reduction (2e-ORR) can directly convert oxygen (O2) into H2O2 and is considered a promising alternative technology. In the electrocatalytic ORR process, O2 is first adsorbed onto the catalyst and forms the *OOH intermediate through a one-step electron transfer. However, the thermodynamically competitive four-electron pathway makes *OOH more likely to generate H2O through homolytic cleavage rather than homolytic pyrolysis to obtain the H2O2 product. Some noble metals, such as PtAu and PaAu, are excellent catalysts for electrocatalytic 2e-ORR. Unfortunately, the high cost of these catalysts limits their large-scale application. Most reported non-precious metal catalysts and carbon materials tend to exhibit 4e-ORR, displaying unsatisfactory H2O2 selectivity and stability. Therefore, designing high-performance catalysts to adjust the adsorption strength and cleavage mode of *OOH is key to improving 2e-ORR efficiency.

[0003] In recent years, single-atom catalysts (SACs) have been shown to possess excellent oxygen reduction capabilities due to their high atomic utilization and independent adsorption sites. Unlike bridging adsorption, single-site adsorption in SACs can avoid heterolytic cleavage of the OO bond in the *OOH transition state, promoting the occurrence of two-electron oxygen reduction processes. Furthermore, the microenvironment of SAC catalysts, including the central atom, coordination number, and second coordination spheres (CSs), plays a crucial role in regulating the electron cloud density and intermediate separation of the active center. Theoretically, the ORR activity catalyzed by SACs depends on the interaction between the *OOH intermediate and the d orbitals of the metal atom, which is considered the source of electrocatalytic activity. Therefore, transition metals with unsaturated d orbitals are widely used in various electrocatalytic systems, while p-blocks with closed d shells are rarely used in electrocatalytic oxygen reduction processes. However, most single-atom catalysts based on d-block elements exhibit thermodynamically more favorable four-electron processes rather than two-electron oxygen reduction processes during electrocatalysis.

[0004] Therefore, in the process of preparing hydrogen peroxide by electrocatalytic two-electron oxygen reduction, how to design high-performance, low-cost catalysts to improve the selectivity and rate of hydrogen peroxide production is an urgent problem to be solved.

[0005] To address the aforementioned problems, this invention is proposed. Summary of the Invention

[0006] To address the problems existing in the prior art, this invention provides a method for preparing p-block element-enhanced dual single-atom materials. This method is the first to utilize the synergistic effect of p-block elements and traditional transition metals to prepare a catalyst with excellent electrocatalytic two-electron oxygen reduction. In the catalyst preparation process, cobalt and gallium elements are introduced into the zeolite imidazole ester precursor via ion exchange, and the coordination environment of the catalyst is controlled by the introduction of sulfur species. Finally, the p-block-enhanced dual single-atom catalyst is synthesized through high-temperature annealing.

[0007] This invention discloses a p-block element-enhanced dual single-atom catalyst, its preparation method, and its application, belonging to the field of catalysts. It solves the problem of poor selectivity in the electrocatalytic two-electron oxygen reduction (OOR) to hydrogen peroxide production of traditional transition metal-based single-atom catalysts. The catalyst preparation process involved in this invention is as follows: cobalt salt, gallium salt, and zinc salt are ion-exchanged with the organic ligand 2-methylimidazolium to form a zeolite imidazolium ester precursor. Trithiocyanate is then introduced into the precursor via chemisorption as a sulfur source. Finally, the target catalyst is synthesized by high-temperature calcination. This invention also discloses the application of this catalyst in the electrocatalytic two-electron oxygen reduction. The introduction of gallium improves the charge distribution of traditional transition metal-based single-atom catalysts, thereby regulating the breakage mode of intermediates during oxygen reduction and greatly improving the selectivity of the oxygen reduction process and the rate of hydrogen peroxide production.

[0008] The present invention adopts the following technical solution:

[0009] The first aspect of this invention provides a p-block element-enhanced dual single-atom catalyst, wherein the p-block element-enhanced dual single-atom catalyst uses cobalt and gallium dual single atoms as active components, and the cobalt and gallium dual single atoms are anchored on a carbon substrate through asymmetric heteroatom coordination. The content of cobalt and gallium dual single atoms is 1.0~5.0 wt%. The p-block element-enhanced dual single-atom catalyst exhibits a porous dodecahedral structure at the microscopic level, with a specific surface area of ​​400~1000 m2 / g and a pore size of 0.5~10 nm.

[0010] A second aspect of the present invention provides a method for preparing the p-block element-enhanced dual single-atom catalyst described in the first aspect of the present invention, comprising the following steps:

[0011] (1) Preparation of zeolite imidazole ester precursor: 2-methylimidazolium was dissolved in a solvent to obtain solution A; cobalt salt, gallium salt and zinc salt were dissolved in a solvent to obtain solution B; solution A and solution B were stirred and mixed and reacted at a certain temperature for a period of time, and then centrifuged, washed and dried to obtain zeolite imidazole ester precursor;

[0012] (2) Preparation of sulfur-doped zeolite imidazole ester precursor: The zeolite imidazole ester precursor obtained in step (1) is added to a solvent, a sulfur source is added to it, and after stirring and sulfidation treatment, the sulfur-doped zeolite imidazole ester precursor is obtained by centrifugation and drying.

[0013] (3) Preparation of P-block element-enhanced double single-atom catalyst: The sulfur-doped zeolite imidazole ester precursor obtained in step (2) is calcined at a certain temperature, and after cooling and further water washing, the P-block element-enhanced double single-atom catalyst is obtained.

[0014] Preferably, in step (1), the cobalt salt, gallium salt, and zinc salt are salts containing cobalt, gallium, or zinc, and the salts used include acetate, nitrate, and chloride.

[0015] The molar ratios of cobalt salt, gallium salt, zinc salt, and 2-methylimidazole used in step (1) are (1~10):(1~10):(1~10):1, respectively.

[0016] The solvents mentioned in steps (1) and (2) include one or a combination of several of water, methanol, dimethyl sulfoxide, acetonitrile and tetrahydrofuran.

[0017] Preferably, in step (1), the reaction time for mixing solution A and solution B is 6~24 h, and the reaction temperature is 10~45℃.

[0018] Preferably, the centrifugation speed for sample collection in step (1) is 6000~11000 rpm, corresponding to a time of 2~10 min.

[0019] Preferably, in step (1), the drying time of the precursor after centrifugation and washing is 6~12 h, and the drying temperature is 60~120℃.

[0020] Preferably, the sulfur source used in step (2) includes thiourea, trithiocyanate, elemental sulfur, or sodium sulfide;

[0021] The mass ratio of sulfur source to zeolite imidazole ester precursor used in step (2) is 1:5 to 1:20, more preferably, the mass ratio of sulfur source to zeolite imidazole ester precursor is 1:20.

[0022] Preferably, the vulcanization time in step (2) is 0.5~3 h and the vulcanization temperature is 10~30 ℃.

[0023] Preferably, in step (3), the sulfur-doped zeolite imidazole ester precursor is calcined in a tube furnace for 2-5 hours at a temperature of 600-1100 °C.

[0024] The third aspect of the present invention provides an application of the p-block element-enhanced double single-atom catalyst described in the first aspect of the present invention, wherein the p-block element-enhanced double single-atom catalyst is used as a catalyst for electrocatalytic two-electron oxygen reduction to produce hydrogen peroxide, thereby improving the selectivity of hydrogen peroxide and the rate of hydrogen peroxide production.

[0025] The catalyst synthesized in this invention is used in the electrocatalytic production of hydrogen peroxide. The technical solution adopted is to adjust the pH of the solution to 13, the system voltage to be between 0 and 1 V (vs. RHE), spin-coat the above catalyst onto a ring disk electrode, and test it in a three-electrode system by rotating the disk electrode. During this process, oxygen is converted into hydrogen peroxide through a two-electron oxygen reduction process.

[0026] Compared with the prior art, the beneficial effects of the present invention are:

[0027] 1. This invention synthesizes a catalyst with excellent two-electron oxygen reduction properties through simple ion co-precipitation, chemisorption, and further high-temperature annealing. The method of this invention provides a simple and reproducible catalyst preparation process with practical application value.

[0028] 2. The catalyst prepared in this invention uses cobalt and gallium dual single atoms as active components. The cobalt and gallium dual single atoms are anchored on a carbon substrate through asymmetric heteroatom coordination. The content of cobalt and gallium dual single atoms is 1.0~5.0 wt%. Microscopically, it exhibits a porous dodecahedral structure with a specific surface area of ​​400~1000 m². 2 With a pore size of 0.5~10 nm, the catalyst's high specific surface area and abundant micro-mesoporous structure provide ample active sites for oxygen adsorption during oxygen reduction.

[0029] 3. This invention constructs a dual-single-atom catalyst by introducing p-block elements onto the surface of a traditional transition metal single-atom catalyst to regulate its microenvironment. This transforms the oxygen reduction process from a four-electron process to a two-electron process for hydrogen peroxide production, solving the problem of poor 2e-ORR performance of traditional transition metal single-atom catalysts. The catalyst of this invention is used for electrocatalytic two-electron oxygen reduction to produce hydrogen peroxide, exhibiting advantages such as high hydrogen peroxide selectivity and high hydrogen peroxide production rate. This has profound significance for expanding the application scenarios of p-block catalysts in the field of electrocatalysis.

[0030] The introduction of gallium improves the charge distribution of traditional transition metal single-atom catalysts, thereby modulating the breakage mode of intermediates in the oxygen reduction process and greatly improving the selectivity of the oxygen reduction process and the rate of hydrogen peroxide production.

[0031] 4. This invention combines DAC catalysts under different microenvironments with the 2e-ORR efficiency of electrocatalysis, which is of guiding significance for revealing the structure-performance relationship of DAC catalysts.

[0032] 5. P-block elements with unsaturated p orbitals can bond with O groups through pp conjugation, thereby regulating the charge density of neighboring transition metal atoms. Based on this, this invention utilizes p-block elements to optimize the local electron density and *OOH adsorption process of traditional transition metal single-atom-based catalysts. This has guiding significance for revealing the structure-performance relationship of SACs catalysts and improving the 2e-ORR selectivity of SACs catalysts. Detailed Implementation

[0034] The technical solution of the present invention will be further described below with reference to specific embodiments. It should be noted that the examples described below are only used to illustrate and explain the present invention in detail, and the application scope of the present invention is not limited by the conditions in the examples. Attached Figure Description

[0035] Figure 1 This is a flowchart illustrating the preparation process of the p-block-enhanced dual single-atom catalyst of the present invention.

[0036] Figure 2 This is the XRD pattern of the p-block-enhanced dual single-atom catalyst synthesized in Example 1 of this invention.

[0037] Figure 3 This is a SEM image of the p-block-enhanced dual single-atom catalyst synthesized in Example 1 of this invention.

[0038] Figure 4 This is a diagram showing the specific surface area and pore size distribution of the p-block-enhanced dual single-atom catalyst synthesized in Example 1 of this invention.

[0039] Figure 5 This is an AC-TEM image of the p-block-enhanced dual single-atom catalyst synthesized in Example 1 of this invention.

[0040] Figure 6 This is an EXAF fitting diagram of the p-block-enhanced dual single-atom catalyst synthesized in Example 1 of this invention.

[0041] Figure 7 This is a cyclic voltammetry curve of the p-block enhanced dual single-atom catalyst synthesized in Example 1 of this invention under nitrogen and oxygen atmospheres.

[0042] Figure 8This is a hydrogen peroxide selectivity diagram of the p-block enhanced dual single-atom catalysts synthesized in Example 1 and Comparative Examples 1-3 of the present invention.

[0043] Figure 9 This is a graph showing the cumulative concentration of hydrogen peroxide in the electrocatalytic two-electron oxygen reduction process of the p-block enhanced dual single-atom catalyst synthesized in Example 1 of this invention.

[0044] Figure 10 This is a graph showing the electrocatalytic two-electron oxygen reduction selectivity of the p-block enhanced dual single-atom catalysts synthesized in Examples 2 to 6 of this invention. Detailed Implementation

[0045] The present invention will be further described below through embodiments, but is not limited to these embodiments. Experimental methods not specifically described in the embodiments generally use conventional conditions and conditions described in manuals, or conditions recommended by the manufacturer. The general equipment, materials, reagents, etc., used are all commercially available unless otherwise specified.

[0046] Example 1: As Figure 1 The process described above.

[0047] Step 1: Preparation of zeolite imidazole ester precursor. 3.08 g of 2-methylimidazole was dissolved in 100 ml of methanol to obtain solution A; 1.365 g of cobalt nitrate hexahydrate, 2.79 g of zinc nitrate hexahydrate, and 0.136 g of gallium nitrate were dissolved in 50 ml of methanol to obtain solution B; solutions A and B were mixed and stirred at 500 rpm for 18 h at 25 °C. After centrifugation at 1000 rpm for 5 min, washing three times with methanol, and then drying in an oven at 60 °C for 12 h, the zeolite imidazole ester precursor was obtained.

[0048] Step 2: Preparation of sulfur-doped zeolite imidazole ester precursor. Take 100 mg of the precursor obtained in step (1) and add it to 30 ml of methanol. Then add 6 mg of trithiocyanate sulfur source to it. Stir at 500 rpm for 0.5 h at 25 ℃. After centrifugation at 1000 rpm for 5 min and washing with methanol 3 times, the sulfur-doped zeolite imidazole ester precursor is obtained.

[0049] Step 3: Preparation of P-block element-enhanced dual single-atom catalyst. The precursor obtained in step (2) was calcined at 950 °C for 3 h in a nitrogen atmosphere at a rate of 5 °C / min. After cooling, it was washed three times with ethanol and three times with water, and then dried in an oven at 60 °C for 12 h to obtain the target catalyst. The obtained catalyst was named CoGa-NS-C, and the contents of cobalt and gallium dual single atoms in the obtained catalyst were 3.1 wt% and 2.8 wt%, respectively.

[0050] like Figure 2 As shown, X-ray diffraction results indicate that the prepared dual single-atom catalyst contains only the typical peaks of carbon materials, with no metal particles present.

[0051] like Figure 3 As shown, scanning electron microscopy results indicate that the synthesized dual single-atom catalyst retains the dodecahedral structure of zeolite imidazole ester and has abundant pore structure.

[0052] like Figure 4 As shown, the nitrogen adsorption-desorption curves indicate that the synthesized dual single-atom catalyst has a specific surface area of ​​400–1000 m². 2 / g, with pore sizes of 0.5~10 nm, the abundant pore structure greatly promotes mass transfer in the oxygen reduction process.

[0053] like Figure 5 As shown, aberration-corrected electron microscopy results indicate that the metal atoms in the synthesized dual single-atom catalyst exist in the form of single atoms.

[0054] like Figure 6 As shown, analysis of the microscopic coordination structure of cobalt and gallium dual single atoms by synchrotron radiation indicates that the synthesized dual single-atom catalyst exists through the coordination structure of the adjacent CoN3S1-GaN4.

[0055] like Figure 7 As shown, by comparing the cyclic voltammetry curves under nitrogen and oxygen atmospheres, it can be seen that the synthesized cobalt and gallium dual single-atom catalyst has obvious redox peaks in the oxygen atmosphere, confirming the occurrence of the reaction.

[0056] like Figure 8 As shown, the catalyst in Example 1 exhibited excellent electrocatalytic two-electron oxygen reduction capability, with obvious redox peaks in the cyclic voltammetry curve in the presence of oxygen; during the rotating disk test, the selectivity of the oxygen reduction process was greater than 90%, demonstrating excellent catalytic performance.

[0057] like Figure 9 As shown, current testing in an H cell confirms that the synthesized cobalt and gallium dual single-atom atoms exhibit excellent hydrogen peroxide generation rate and stability.

[0058] Example 2:

[0059] Step 1: Preparation of zeolite imidazole ester precursor. 1.54 g of 2-methylimidazole was dissolved in 100 ml of methanol to obtain solution A; 1.365 g of cobalt nitrate hexahydrate, 2.79 g of zinc nitrate hexahydrate, and 0.136 g of gallium nitrate were dissolved in 50 ml of methanol to obtain solution B; solutions A and B were mixed and stirred at 500 rpm for 18 h at 25 °C. After centrifugation at 1000 rpm for 5 min, washing three times with methanol, and then drying in an oven at 60 °C for 12 h, the zeolite imidazole ester precursor was obtained.

[0060] Step 2: Preparation of sulfur-doped zeolite imidazole ester precursor. Take 100 mg of the precursor obtained in step (1) and add it to 30 ml of methanol. Then add 6 mg of trithiocyanate and stir at 500 rpm for 0.5 h at 25 ℃. After centrifugation at 1000 rpm for 5 min and washing with methanol 3 times, the sulfur-doped zeolite imidazole ester precursor is obtained.

[0061] Step 3: Preparation of P-block element-enhanced dual single-atom catalyst. The precursor obtained in step (2) was calcined at 950 °C for 3 h in a nitrogen atmosphere at a rate of 5 °C / min. After cooling, it was washed three times with ethanol and three times with water, and then dried in an oven at 60 °C for 12 h to obtain the target catalyst.

[0062] Example 3:

[0063] Step 1: Preparation of zeolite imidazole ester precursor. 3.08 g of 2-methylimidazole was dissolved in 100 ml of methanol to obtain solution A; 1.365 g of cobalt nitrate hexahydrate, 2.79 g of zinc nitrate hexahydrate, and 0.136 g of gallium nitrate were dissolved in 50 ml of methanol to obtain solution B; solutions A and B were mixed and stirred at 500 rpm for 18 h at 25 °C. After centrifugation at 1000 rpm for 5 min, washing three times with methanol, and then drying in an oven at 60 °C for 12 h, the zeolite imidazole ester precursor was obtained.

[0064] Step 2: Preparation of sulfur-doped zeolite imidazole ester precursor. Take 100 mg of the precursor obtained in step (1) and add it to 30 ml of methanol. Then add 6 mg of thiourea to the mixture. Stir at 500 rpm for 0.5 h at 25 ℃. After centrifugation at 1000 rpm for 5 min and washing with methanol 3 times, the sulfur-doped zeolite imidazole ester precursor is obtained.

[0065] Step 3: Preparation of P-block element-enhanced dual single-atom catalyst. The precursor obtained in step (2) was calcined at 950 °C for 3 h in a nitrogen atmosphere at a rate of 5 °C / min. After cooling, it was washed three times with ethanol and three times with water, and then dried in an oven at 60 °C for 12 h to obtain the target catalyst.

[0066] Example 4:

[0067] Step 1: Preparation of zeolite imidazole ester precursor. 3.08 g of 2-methylimidazole was dissolved in 100 ml of methanol to obtain solution A; 1.365 g of cobalt nitrate hexahydrate, 2.79 g of zinc nitrate hexahydrate, and 0.136 g of gallium nitrate were dissolved in 50 ml of methanol to obtain solution B; solutions A and B were mixed and stirred at 500 rpm for 18 h at 25 °C. After centrifugation at 1000 rpm for 5 min, washing three times with methanol, and then drying in an oven at 60 °C for 12 h, the zeolite imidazole ester precursor was obtained.

[0068] Step 2: Preparation of sulfur-doped zeolite imidazole ester precursor. Take 100 mg of the precursor obtained in step (1) and add it to 30 ml of methanol. Then add 6 mg of thiourea to the mixture. Stir at 500 rpm for 0.5 h at 25 ℃. After centrifugation at 1000 rpm for 5 min and washing with methanol 3 times, the sulfur-doped zeolite imidazole ester precursor is obtained.

[0069] Step 3: Preparation of P-block element-enhanced dual single-atom catalyst. The precursor obtained in step (2) was calcined at 800 °C for 3 h in a nitrogen atmosphere at a rate of 5 °C / min. After cooling, it was washed three times with ethanol and three times with water, and then dried in an oven at 60 °C for 12 h to obtain the target catalyst.

[0070] Example 5:

[0071] Step 1: Preparation of zeolite imidazole ester precursor. 1.54 g of 2-methylimidazole was dissolved in 100 ml of methanol to obtain solution A; 1.365 g of cobalt nitrate hexahydrate, 2.79 g of zinc nitrate hexahydrate, and 0.136 g of gallium nitrate were dissolved in 50 ml of methanol to obtain solution B; solutions A and B were mixed and stirred at 500 rpm for 18 h at 25 °C, centrifuged at 1000 rpm for 5 min, washed three times with methanol, and then dried in an oven at 60 °C for 12 h to obtain the zeolite imidazole ester precursor.

[0072] Step 2: Preparation of sulfur-doped zeolite imidazole ester precursor. Take 100 mg of the precursor obtained in step (1) and add it to 30 ml of methanol. Then add 6 mg of thiourea to the mixture. Stir at 500 rpm for 0.5 h at 25 ℃. After centrifugation at 1000 rpm for 5 min and washing with methanol 3 times, the sulfur-doped zeolite imidazole ester precursor is obtained.

[0073] Step 3: Preparation of P-block element-enhanced dual single-atom catalyst. The precursor obtained in step (2) was calcined at 800 °C for 3 h in a nitrogen atmosphere at a rate of 5 °C / min. After cooling, it was washed three times with ethanol and three times with water, and then dried in an oven at 60 °C for 12 h to obtain the target catalyst.

[0074] Example 6:

[0075] Step 1: Preparation of zeolite imidazole ester precursor. 3.08 g of 2-methylimidazole was dissolved in 100 ml of methanol to obtain solution A; 1.365 g of cobalt chloride hexahydrate, 2.79 g of zinc chloride, and 0.136 g of gallium chloride were dissolved in 50 ml of methanol to obtain solution B; solutions A and B were mixed and stirred at 500 rpm for 18 h at 25 °C. After centrifugation at 1000 rpm for 5 min, washing three times with methanol, and then drying in an oven at 60 °C for 12 h, the zeolite imidazole ester precursor was obtained.

[0076] Step 2: Preparation of sulfur-doped zeolite imidazole ester precursor. Take 100 mg of the precursor obtained in step (1) and add it to 30 ml of methanol. Then add 6 mg of trithiocyanate and stir at 500 rpm for 0.5 h at 25 ℃. After centrifugation at 1000 rpm for 5 min and washing with methanol 3 times, the sulfur-doped zeolite imidazole ester precursor is obtained.

[0077] Step 3: Preparation of P-block element-enhanced dual single-atom catalyst. The precursor obtained in step (2) was calcined at 800 °C for 3 h in a nitrogen atmosphere at a rate of 5 °C / min. After cooling, it was washed three times with ethanol and three times with water, and then dried in an oven at 60 °C for 12 h to obtain the target catalyst.

[0078] like Figure 10 As shown in Examples 2-6, different metal contents have a significant impact on the selectivity of the electrocatalytic two-electron oxygen reduction catalyst. Furthermore, combined with… Figure 8 It can be seen that Example 1 exhibits the best two-electron oxygen reduction selectivity.

[0079] Comparative Example 1

[0080] Step 1: Preparation of zeolite imidazole ester precursor. 3.08 g of 2-methylimidazole was dissolved in 100 ml of methanol to obtain solution A; 1.365 g of cobalt nitrate hexahydrate, 2.79 g of zinc nitrate hexahydrate, and 0.136 g of gallium nitrate were dissolved in 50 ml of methanol to obtain solution B; solutions A and B were mixed and stirred at 500 rpm for 18 h at 25 °C. After centrifugation at 1000 rpm for 5 min, washing three times with methanol, and then drying in an oven at 60 °C for 12 h, the zeolite imidazole ester precursor was obtained.

[0081] Step 2: Preparation of P-block element-enhanced dual single-atom catalyst. The precursor obtained in step (2) was calcined at 950 °C for 3 h in a nitrogen atmosphere at a rate of 5 °C / min. After cooling, it was washed three times with ethanol and three times with water, and then dried in an oven at 60 °C for 12 h to obtain the target catalyst, which was named CoGa-NC.

[0082] The catalyst preparation does not involve the process of regulating its microenvironment through sulfide adsorption.

[0083] Comparative Example 2

[0084] Step 1: Preparation of zeolite imidazole ester precursor. 3.08 g of 2-methylimidazole was dissolved in 100 ml of methanol to obtain solution A; 1.365 g of cobalt nitrate hexahydrate and 2.79 g of zinc nitrate hexahydrate were dissolved in 50 ml of methanol to obtain solution B; solutions A and B were mixed and stirred at 500 rpm for 18 h at 25 °C, centrifuged at 1000 rpm for 5 min, washed three times with methanol, and then dried in an oven at 60 °C for 12 h to obtain the zeolite imidazole ester precursor.

[0085] Step 2: Preparation of P-block element-enhanced dual single-atom catalyst. The precursor obtained in step (2) was calcined at 950 °C for 3 h in a nitrogen atmosphere at a rate of 5 °C / min. After cooling, it was washed three times with ethanol and three times with water, and then dried in an oven at 60 °C for 12 h to obtain the target catalyst, which was named Co-NC.

[0086] The catalyst is a single-atom catalyst because it does not involve the process of regulating its microenvironment through sulfidation adsorption and does not introduce gallium species during its preparation.

[0087] Comparative Example 3

[0088] Step 1: Preparation of zeolite imidazole ester precursor. 3.08 g of 2-methylimidazole was dissolved in 100 ml of methanol to obtain solution A; 2.79 g of zinc nitrate hexahydrate and 0.136 g of gallium nitrate were dissolved in 50 ml of methanol to obtain solution B; solutions A and B were mixed and stirred at 500 rpm for 18 h at 25 °C. After centrifugation at 1000 rpm for 5 min, washing three times with methanol, and then drying in an oven at 60 °C for 12 h, the zeolite imidazole ester precursor was obtained.

[0089] Step 2: Preparation of P-block element-enhanced dual single-atom catalyst. The precursor obtained in step (1) was calcined at 950 °C for 3 h in a nitrogen atmosphere at a rate of 5 °C / min. After cooling, it was washed three times with ethanol and three times with water, and then dried in an oven at 60 °C for 12 h to obtain the target catalyst, which was named Ga-NC.

[0090] The catalyst is a single-atom catalyst because it does not involve the process of regulating its microenvironment through sulfidation adsorption and does not introduce cobalt species during its preparation.

[0091] The above description is only used to detail the specific embodiments of the present invention, but the technical solutions proposed by the present invention are not limited to the above methods. All equivalent modifications and variations made by those skilled in the art to the technology proposed by the present invention without departing from the basic principles of the present invention should be covered within the scope of the claims of the present invention.

Claims

1. A p-block element-enhanced dual single-atom catalyst, characterized in that, The p-block element-enhanced dual-single-atom catalyst uses cobalt and gallium dual-single atoms as active components. The cobalt and gallium dual-single atoms are anchored to a carbon substrate through asymmetric heteroatom coordination. The content of each cobalt and gallium dual-single atom is 1.0-5.0 wt%. The p-block element-enhanced dual-single-atom catalyst exhibits a porous dodecahedral structure with a specific surface area of ​​400-1000 m². 2 / g, with a pore size of 0.5-10 nm; The p-block element-enhanced dual single-atom catalyst is prepared by the following method, including the following steps: (1) Preparation of zeolite imidazole ester precursor: Dissolve 3.08 g of 2-methylimidazole in 100 ml of methanol to obtain solution A; dissolve 1.365 g of cobalt nitrate hexahydrate, 2.79 g of zinc nitrate hexahydrate and 0.136 g of gallium nitrate in 50 ml of methanol to obtain solution B; or dissolve 1.54 g of 2-methylimidazole in 100 ml of methanol to obtain solution A; dissolve 1.365 g of cobalt nitrate hexahydrate, 2.79 g of zinc nitrate hexahydrate and 0.136 g of gallium nitrate in 50 ml of methanol to obtain solution B; After mixing solution A and solution B and reacting them at a certain temperature for a period of time, the zeolite imidazole ester precursor was obtained by centrifugation, washing and drying. (2) Preparation of sulfur-doped zeolite imidazole ester precursor: The zeolite imidazole ester precursor obtained in step (1) is added to a solvent, a sulfur source is added to it, and after stirring and sulfidation treatment, the sulfur-doped zeolite imidazole ester precursor is obtained by centrifugation and drying. (3) Preparation of P-block element-enhanced double single-atom catalyst: The sulfur-doped zeolite imidazole ester precursor obtained in step (2) is calcined at a certain temperature, and after cooling and further water washing, the P-block element-enhanced double single-atom catalyst is obtained. In step (2), the vulcanization time is 0.5-3 h and the vulcanization temperature is 10-30℃; The mass ratio of sulfur source and zeolite imidazole ester precursor used in step (2) is 1:5-1:20; In step (3), the calcination time is 2-5 h and the calcination temperature is 600-1100℃.

2. The p-block element-enhanced dual single-atom catalyst according to claim 1, characterized in that, In step (1), the reaction time for mixing solution A and solution B is 6-24 h, and the reaction temperature is 10-45℃.

3. The p-block element-enhanced dual single-atom catalyst according to claim 1, characterized in that, In step (1), the sample is collected by centrifugation at a speed of 6000-11000 rpm for a time of 2-10 min.

4. The p-block element-enhanced dual single-atom catalyst according to claim 1, characterized in that, In step (1), the drying time is 6-12 h and the drying temperature is 60-120℃.

5. The p-block element-enhanced dual single-atom catalyst according to claim 1, characterized in that, The sulfur source used in step (2) includes thiourea, trithiocyanate, elemental sulfur, or sodium sulfide.

6. The application of the p-block element-enhanced dual single-atom catalyst according to any one of claims 1-5, characterized in that, The p-block element-enhanced dual single-atom catalyst was used as a catalyst for electrocatalytic two-electron oxygen reduction to produce hydrogen peroxide, thereby improving the selectivity of hydrogen peroxide and the rate of hydrogen peroxide production.

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