Universal method for proton adsorption induction of ultrahigh surface metal monatomic load

Abstract

The invention discloses a universal method for proton adsorption induced ultrahigh surface metal monatomic loading, which comprises the following steps: (S1) uniformly dispersing a carrier subjected to protonation treatment by a strong acid solution or an organic solvent in a metal salt aqueous solution to obtain an acid mixed solution; (S2) carrying out drying treatment on the acidic mixed solution containing the carrier and metal salt ions, then grinding into powder, and carrying out secondary drying; and (S3) putting the powder obtained by grinding into a tubular furnace, and calcining in two steps under inert gas so as to form monatomic active sites on the surface of the catalytic material, thereby obtaining the ultrahigh surface metal monatomic loaded catalytic material. The method disclosed by the invention is simple to operate, wide in application range, uniform in sample dispersion and extremely high in monatomic surface density, the loading capacity can reach more than 30wt%, and abundant reaction active sites are provided for catalytic reaction. The monatomic catalytic material prepared by the method has excellent catalytic performance.

Description

Technical Field

[0001] The present invention belongs to the field of preparation of new energy catalytic materials, and specifically relates to a universal method for inducing ultra-high surface metal single atom loading by proton adsorption. Background Art

[0002] As a green and environmentally friendly catalytic technology, new energy catalysis holds broad development prospects due to its important applications in environmental governance and energy conversion. Single-atom catalysts (SACs) have become a research hotspot in this field due to their unique structural properties, exhibiting high catalytic activity, excellent selectivity, and good stability.

[0003] The synthesis of single-atom catalysts faces two key challenges: 1) low metal loading; and 2) lack of universal applicability. This is because isolated atoms have high surface energy, making them prone to migration and aggregation under practical reaction conditions, forming nanoparticles. Therefore, depending on the loading, single-atom catalysts can be categorized into three main groups: low-concentration loading (loadings below 10 wt%), high-concentration loading (loadings between 10 wt% and 30 wt%), and ultrahigh-concentration loading (loadings exceeding 30 wt%). Currently, researchers have developed a variety of methods for synthesizing single-atom catalysts (SACs), primarily including atomic layer deposition (ALD), chemical vapor deposition (CVD), wet chemical methods, and thermal decomposition. Notably, to date, single-atom catalysts prepared by ALD, CVD, and methods typically achieve metal loadings below 5 wt%. In contrast, thermal decomposition and wet chemical methods can achieve higher metal loadings (≥5 wt%), but rarely exceed 20 wt%. Therefore, a universal method for proton adsorption-induced ultrahigh surface metal single-atom loading is needed.

[0004] It should be noted that the information disclosed in the above background technology section is only used to enhance the understanding of the background of the present disclosure, and therefore may include information that does not constitute prior art known to ordinary technicians in the field. Summary of the Invention

[0005] The purpose of the present invention is to provide a universal method for proton adsorption-induced ultra-high surface metal single atom loading. This method adopts a top-down strategy to synthesize atomically dispersed and ultra-high concentration loaded single atom-loaded catalytic materials, which can effectively solve the problems of agglomeration and uneven distribution of active sites in traditional catalytic materials, effectively increase the single atom loading concentration, and thus improve the catalytic performance of the material.

[0006] To achieve the above objectives, the present invention provides a universal method for proton adsorption-induced ultrahigh surface metal single atom loading, which comprises the following steps: (S1) uniformly dispersing the support protonated by a strong acid solution or an organic solvent in a metal salt aqueous solution to obtain a mixed solution; (S2) drying the acidic mixed solution containing the carrier and the metal salt ions, grinding it into powder, and then drying it for a second time; (S3) The ground powder is placed in a tubular furnace and calcined in an inert gas atmosphere in two steps. First, the powder is kept at a constant temperature for a period of time at a low temperature to reduce the crystalline water content in the powder. The low temperature (100-400°C) should be greater than the boiling point of water and less than the decomposition temperature of the loaded soluble metal salt. The powder is then heated to a high temperature of 400-600°C and subjected to a high-temperature pyrolysis treatment to completely vaporize the mixed raw materials, thereby forming single-atom active sites on the surface of the catalytic material, thereby obtaining a catalytic material with ultra-high surface metal single-atom loading.

[0007] Preferably, in step (S1), the metal salt aqueous solution is added to the carrier that has been protonated with a strongly acidic aqueous solution or an organic solvent, and ultrasonically dispersed for 0.5 to 1 h to obtain a mixed solution.

[0008] Preferably, in step (S1), the acid used in the strong acidic solution or organic solvent is selected from any one of nitric acid, sulfuric acid and hydrochloric acid; more preferably, the acid used is selected from sulfuric acid.

[0009] Preferably, in step (S1), the organic solvent is selected from any one of acetone, methanol and ethanol; more preferably, the organic solvent is selected from ethanol.

[0010] Preferably, in step (S1), the amount of the strongly acidic solution or organic solvent added is 2-5 mL / g; more preferably, the amount of the strongly acidic aqueous solution or organic solvent added is 3 mL / g.

[0011] Preferably, in step (S1), the carrier is selected from any one of borides, carbides and nitrogen compounds.

[0012] Preferably, the metal single atom is selected from any one of calcium (Ca), chromium (Cr), manganese (Mn), iron (Fe), copper (Cu), cobalt (Co), nickel (Ni), zinc (Zn), molybdenum (Mo), indium (In), lanthanum (La), cerium (Ce), praseodymium (Pr), gold (Au), silver (Ag), platinum (Pt), palladium (Pd), rhodium (Rh), ruthenium (Ru), osmium (Os), iridium (Ir) and antimony (Sb).

[0013] Preferably, in step (S2), the first drying is to evaporate the mixed solution to dryness at 95°C; the second drying is to be performed at 130°C; and the grinding time is 15 minutes.

[0014] Preferably, in step (S3), before the sample is placed in the tube furnace, an inert gas is introduced into the tube furnace for 10 to 20 minutes; the inert gas is selected from argon, helium, nitrogen or xenon; the heating rate of the calcination is 5 to 8 ° C / min, the low-temperature calcination time of 100 to 400 ° C is 9 hours, and the high-temperature calcination time of 400 to 600 ° C is 1 hour.

[0015] Preferably, in step (S3), the high temperature is 550°C.

[0016] Another object of the present invention is to provide a catalytic material obtained by the universal method of proton adsorption-induced ultra-high surface metal single atom loading.

[0017] Preferably, the catalytic material is 35 wt% Ag, Cu, Fe, Pr or Cd single atoms loaded on a graphene carbon nitride substrate, or 25 wt% Pr single atoms loaded on a hexagonal boron nitride substrate.

[0018] Preferably, a catalytic material with 35 wt% Ag single atoms loaded on a graphene carbon nitride substrate can be used for photocatalytic reduction of CO2 to produce H2.

[0019] The universal method of the present invention for proton adsorption-induced ultra-high surface metal single atom loading has the following advantages: The present invention adopts a fully protonated carrier and utilizes the principle of pyrolysis-induced vaporization. The loaded raw material is vaporized at high temperature. In this atmosphere, the catalyst successfully anchors the single-atom active site to the surface of the catalyst precursor, while the remaining substances are blown out of the furnace by the inert gas, thereby realizing the regulation of the concentration, type and coordination configuration of the single atom. Most importantly, the proton adsorption of the carrier during the preparation process can not only induce the formation of active sites, but also prevent the agglomeration of the loaded elements at high temperatures, thereby further optimizing the surface properties and catalytic performance of the catalyst and improving the efficiency and stability of the photocatalytic reaction. The method is simple to operate, has a wide range of applications, the sample is evenly dispersed, the single-atom surface density is extremely high, and the loading amount can reach more than 30 wt%. The single-atom catalytic material prepared by this method exhibits excellent catalytic performance in the field of photocatalysis, such as high activity, high stability, etc., and can significantly improve the efficiency of the catalytic reaction and the quality of the product. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] FIG1 is a transmission electron micrograph (A, B) of the 35 wt%-Ag / g-C3N4 single-atom catalyst prepared in Example 1 of the present invention at two different positions.

[0021] Figure 2 1 is the XRD pattern of the g-C3N4 substrate and the catalyst after loading elements prepared in Examples 1 to 5 of the present invention.

[0022] Figure 3 is a performance diagram of the photocatalytic reduction of CO2 to produce H2 by the 35 wt%-Ag / g-C3N4 photocatalyst and the g-C3N4 photocatalyst prepared in Example 1; wherein, (A) is the yield of H2 generated by g-C3N4 and 35 wt%-Ag / g-C3N4 photocatalysts within 4 hours; (B) is the yield corresponding to the 35 wt%-Ag / g-C3N4 photocatalyst cycle experiment.

[0023] Figure 4 is a comparison of the CO2 reduction performance of g-C3N4 substrate and single-atom catalysts loaded with different metals.

[0024] FIG5 is an XRD pattern of the BN substrate and the 25 wt%-Pr / BN photocatalyst prepared in Example 6 of the present invention.

[0025] FIG6 is the XRD pattern of the 35 wt%-Ag / g-C3N4 single atom catalyst prepared under different conditions of the present invention. DETAILED DESCRIPTION

[0026] The following is a clear and complete description of the technical solutions in the embodiments of the present invention. Obviously, the embodiments described are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making any creative efforts are within the scope of protection of the present invention.

[0027] Note: If specific conditions are not specified in the examples, the experiments were conducted under conventional conditions or those recommended by the manufacturer. Instruments used without manufacturer information are commercially available. Raw materials and reagents used without manufacturer information are commercially available or can be prepared by known methods.

[0028] Throughout this disclosure, all features, such as values, amounts, amounts, and concentrations, specified in numerical ranges or percentage ranges are provided for simplicity and convenience only. Accordingly, the description of numerical ranges or percentage ranges should be considered to encompass and specifically disclose all possible subranges and individual values ​​within those ranges (including integers and fractions).

[0029] The features described in this disclosure may be combined in any manner, and as long as there are no conflicts between the combinations of these features, all possible combinations should be considered within the scope of this specification. Each feature disclosed in this specification may be replaced by any alternative feature that provides the same, equivalent, or similar purpose. Therefore, unless otherwise specified, the features disclosed are merely general examples of equivalent or similar features.

[0030] Example 1 A universal method for proton adsorption-induced ultrahigh surface metal single-atom loading is described. 35 wt% Ag (35 wt%-Ag / g-C3N4) single atoms are loaded onto a graphene carbon nitride substrate (g-C3N4). Based on the Ag loading, 0.35 g of Ag is required for 1 g of the catalyst precursor. Since Ag is obtained from AgNO3, the required AgNO3 content needs to be determined. Given the molecular weight of Ag is 107.8682 and the molecular weight of AgNO3 is 169.87, the required AgNO3 mass is calculated as 0.35 g ÷ (107.8682 / 169.87) = 0.5112 g, according to the formula: Metal salt mass = metal loading ÷ (metal molecular weight / metal salt molecular weight). The method includes the following steps:

[0031] (1) Weigh 25.0 g of dicyandiamide and place it in a porcelain boat. Then, heat it from 30 °C to 550 °C in a muffle furnace at a heating rate of 10 °C / min and keep it at 550 °C for 1 h. After cooling, grind it thoroughly to prepare g-C3N4. (2) Weigh 0.511 g of AgNO3 and dissolve it in 10 mL of deionized water. Ultrasonicate for 10 min to completely dissolve it. Weigh 1 g of g-C3N4 passed through a 100-mesh sieve and add it to the AgNO3 solution. Add 3 mL of concentrated nitric acid to the solution to protonate it. Ultrasonicate again for 0.5 h to evenly disperse the g-C3N4 in the solution to obtain a mixed solution.

[0032] (3) The mixed solution was placed on a 95 °C evaporation table for evaporation. After it was completely evaporated, the sample was ground into powder using a mortar and pestle. The powder was ground for 15 min to fully mix the g-C3N4 and the raw material to be loaded. The powder was then placed in a porcelain boat and dried again on a heating table at 130 °C for 2 h to remove as much water as possible absorbed by the sample during the grinding process. (4) The porcelain boat containing the sample was placed in a tube furnace and calcined in two steps under argon protection. The heating rate during the calcination process was 8 °C / min. It was first calcined at 230 °C for 9 h, and then heated to 550 °C for 1 h to obtain a 35 wt%-Ag / g-C3N4 single atom catalyst.

[0033] The prepared 35 wt%-Ag / g-C3N4 single atom catalyst was observed using spherical aberration corrected transmission electron microscopy. Figure 1 As shown, Figure 1 Figures (A) and (B) are spherical aberration transmission electron microscopy images of 35 wt%-Ag / g-C3N4 single atom catalyst at two different positions. It can be seen that the entire Ag metal element is uniformly deposited on the surface of g-C3N4.

[0034] The prepared 35 wt%-Ag / g-C3N4 monatomic catalyst was characterized by XRD, and the results are shown in Figure 2 As Ag was added, no characteristic peaks of Ag appeared on the XRD pattern, indicating that Ag atoms were uniformly supported on the g-C3N4 matrix.

[0035] When the catalyst was tested for photocatalytic reduction of CO2, 200 mg of catalyst sample was first uniformly dispersed on 200 mg of quartz wool, then 1 mL of deionized water was added to the reactor and filled with CO2 gas inside. The reactor was heated to 180 ℃ and continuously irradiated under a full-spectrum xenon lamp with an intensity of 1.5 W / cm 2 for 4 h, and its catalytic performance was from Figure 3 (A) It can be seen that after loading Ag monatomic, the photocatalytic performance of the catalyst is obviously improved, and the yield of H2 is increased by nearly 5 times under the same test conditions. From Figure 3 (B) It can be seen that the yield of H2 does not have a significant downward trend in the 6-cycle experiment of 35 wt%-Ag / g-C3N4 monatomic catalyst, which shows that the monatomic catalyst prepared by this method has good stability.

[0036] Example 2 A universal method for loading proton-adsorption-induced ultra-high surface metal monatomic on graphene carbon nitride substrate (g-C3N4) loaded 35 wt% Cu (35 wt%-Cu / g-C3N4) monatomic, which comprises the following steps: (1) The preparation of g-C3N4 is the same as in Example 1; (2) 1.033 g of Cu(NO3)2 was weighed and dissolved in 10 mL of deionized water, and ultrasonic was performed for 10 min to make it completely dissolved. 1 g of g-C3N4 sieved through a 100 mesh sieve was added to the Cu(NO3)2 solution, 3 mL of concentrated nitric acid was added to the solution for protonation treatment, and ultrasonic was performed again for 0.5 h to make the g-C3N4 uniformly dispersed in the solution;

[0037] (3) The mixed solution was placed on a 95 ℃ evaporation table for evaporation. After complete evaporation, the sample was ground into powder with a mortar, and grinding was performed for 15 min to make the g-C3N4 and the loaded material fully mixed, then the powder was placed in a porcelain boat, and it was dried again at 130 ℃ in a heating table for 2 h to remove as much water as possible absorbed during the grinding process;

[0038] (4) The porcelain boat containing the sample was placed in a tube furnace and calcined in two steps under argon protection. The heating rate during the calcination process was 8 °C / min. It was first calcined at 160 °C for 9 h, and then heated to 550 °C for 1 h to obtain a 35 wt%-Cu / g-C3N4 single-atom catalyst.

[0039] The results are as follows Figure 2 As shown in the figure, with the addition of Cu, no characteristic peak of Cu appears in the XRD pattern, indicating that Cu atoms are uniformly loaded on the g-C3N4 matrix.

[0040] Example 3 A universal method for proton adsorption-induced ultrahigh surface metal single atom loading was developed to load 35 wt% Fe (35 wt%-Fe / g-C3N4) single atoms on a graphene carbon nitride substrate (g-C3N4). The method includes the following steps: (1) The preparation of g-C3N4 is the same as in Example 1; (2) Weigh 1.033 g of Fe(NO3)3 and dissolve it in 10 mL of deionized water. Ultrasonicate for 10 min to completely dissolve it. Weigh 1 g of g-C3N4 (passed through a 100-mesh sieve) and add it to the Fe(NO3)3 solution. Add 3 mL of concentrated nitric acid to the solution to protonate it. Ultrasonicate again for 0.5 h to ensure that the g-C3N4 is evenly dispersed in the solution.

[0041] (3) The mixed solution was placed on a 95 °C evaporation table for evaporation. After it was completely evaporated, the sample was ground into powder using a mortar and pestle. The powder was ground for 15 min to fully mix the g-C3N4 and the raw material to be loaded. The powder was then placed in a porcelain boat and dried again on a heating table at 130 °C for 2 h to remove as much water as possible absorbed by the sample during the grinding process. (4) The porcelain boat containing the sample was placed in a tube furnace and calcined in two steps under argon protection. The heating rate during the calcination process was 8 °C / min. It was first calcined at 120 °C for 9 h, and then heated to 550 °C for 1 h to obtain a 35 wt%-Fe / g-C3N4 single-atom catalyst.

[0042] The results are as follows Figure 2 As shown in the figure, with the addition of Fe, no characteristic peak of Fe appears in the XRD pattern, indicating that the Fe atoms are uniformly loaded on the g-C3N4 matrix.

[0043] Example 4 A universal method for proton adsorption-induced ultrahigh surface metal single-atom loading was developed to load 35 wt% Pr (35 wt%-Pr / g-C3N4) single atoms on a graphene carbon nitride substrate (g-C3N4). The method includes the following steps: (1) The preparation of g-C3N4 is the same as in Example 1; (2) Weigh 1.081 g of Pr(NO3)3·6H2O and dissolve it in 10 mL of deionized water. Ultrasonicate for 10 min to completely dissolve it. Weigh 1 g of g-C3N4 (passed through a 100-mesh sieve) and add it to the Pr(NO3)3 solution. Add 3 mL of concentrated nitric acid to the solution to protonate it. Ultrasonicate again for 0.5 h to ensure that the g-C3N4 is evenly dispersed in the solution.

[0044] (3) The mixed solution was placed on a 95 °C evaporation table for evaporation. After it was completely evaporated, the sample was ground into powder using a mortar and pestle. The powder was ground for 15 min to fully mix the g-C3N4 and the raw material to be loaded. The powder was then placed in a porcelain boat and dried again on a heating table at 130 °C for 2 h to remove as much water as possible absorbed by the sample during the grinding process. (4) The porcelain boat containing the sample was placed in a tube furnace and calcined in two steps under argon protection. The heating rate during the calcination process was 8 °C / min. It was first calcined at 130 °C for 9 h, and then heated to 550 °C for 1 h to obtain a 35 wt%-Pr / g-C3N4 single-atom catalyst.

[0045] The results are as follows Figure 2 As shown in the figure, with the addition of Pr, no characteristic peak of Pr appears in the XRD pattern, indicating that Pr atoms are uniformly loaded on the g-C3N4 matrix.

[0046] Example 5 A universal method for proton adsorption-induced ultrahigh surface metal single-atom loading was developed to load 35 wt% Cd (35 wt%-Cd / g-C3N4) single atoms onto a graphene carbon nitride substrate (g-C3N4). The method includes the following steps: (1) The preparation of g-C3N4 is the same as in Example 1; (2) Weigh 1.602 g of Cd(NO3)3 and dissolve it in 10 mL of deionized water. Ultrasonicate for 10 min to completely dissolve it. Weigh 1 g of g-C3N4 passed through a 100-mesh sieve and add it to the Cd(NO3)3 solution. Add 3 mL of concentrated nitric acid to the solution to protonate it. Ultrasonicate again for 0.5 h to ensure that the g-C3N4 is evenly dispersed in the solution.

[0047] (3) The mixed solution was placed on a 95 °C evaporation table for evaporation. After it was completely evaporated, the sample was ground into powder using a mortar and pestle. The powder was ground for 15 min to fully mix the g-C3N4 and the raw material to be loaded. The powder was then placed in a porcelain boat and dried again on a heating table at 130 °C for 2 h to remove as much water as possible absorbed by the sample during the grinding process. (4) The porcelain boat containing the sample was placed in a tube furnace and calcined in two steps under argon protection. The heating rate during the calcination process was 8 °C / min. It was first calcined at 130 °C for 9 h, and then heated to 550 °C for 1 h to obtain a 35 wt%-Cd / g-C3N4 single-atom catalyst.

[0048] The results are as follows Figure 2 As shown in the figure, with the addition of Cd, no characteristic peak of Cd appears in the XRD pattern, indicating that Cd atoms are uniformly loaded on the g-C3N4 matrix.

[0049] The high-loaded single-atom catalysts prepared in Examples 2, 3, 4, and 5 were tested for photocatalytic CO2 reduction. Figure 4 As shown, the yield of successfully loaded single-atom photocatalysts was significantly improved compared with the g-C3N4 substrate.

[0050] Example 6 A universal method for proton adsorption-induced ultrahigh surface metal single atom loading is disclosed. 25 wt% Pr (25 wt%-Pr / BN) single atoms are loaded on a hexagonal boron nitride (BN) substrate. The raw materials used are hexagonal boron nitride (BN) and praseodymium nitrate hexahydrate (Pr(NO3)3·6H2O). According to the formula in Example 1, the required mass of Pr(NO3)3·6H2O is 0.772 g. The method comprises the following steps: (1) Weigh 0.772 g of Pr(NO3)3·6H2O and dissolve it in 10 mL of deionized water. Ultrasonicate for 10 min to completely dissolve it. Weigh 1 g of BN and add it to the Pr(NO3)3 solution. Add 3 mL of concentrated nitric acid to the solution to protonate it. Ultrasonicate again for 0.5 h to ensure that the BN is evenly dispersed in the solution.

[0051] (2) The mixed solution was placed on a 95°C evaporation table for evaporation. After it was completely evaporated, the sample was ground into powder using a mortar and pestle. The powder was ground for 15 minutes to fully mix the BN and the raw material to be loaded. The powder was then placed in a porcelain boat and dried again on a heating table at 130°C for 2 hours to remove as much water as possible absorbed by the sample during the grinding process. (3) The porcelain boat containing the sample was placed in a tube furnace and calcined in two steps under argon protection. The heating rate during the calcination process was 8 °C / min. It was first calcined at 130 °C for 9 h, and then heated to 550 °C for 1 h to obtain a 35 wt%-Pr / BN single atom catalyst.

[0052] The results are as follows Figure 5 As shown in Figure 3, with the addition of Pr, no characteristic peak of Pr appears in the XRD pattern, indicating that Pr atoms are uniformly loaded on the BN matrix.

[0053] Since Ag has a high atomic number and a strong ability to scatter X-rays, the diffraction peak intensity is usually more obvious. Therefore, in the comparative experiments, the supported Ag single-atom catalyst is mainly used as a comparative example.

[0054] Comparative Example 1 A universal method for proton adsorption-induced ultrahigh surface metal single atom loading is described. 35 wt% Ag (35 wt%-Ag / g-C3N4) single atoms are loaded on graphene carbon nitride substrates (g-C3N4) without protonation. The method comprises the following steps: (1) The preparation of g-C3N4 is the same as in Example 1; (2) Weigh 0.511 g of AgNO3 and dissolve it in 10 mL of deionized water. Ultrasonicate for 10 min to completely dissolve it. Weigh 1 g of g-C3N4 (passed through a 100-mesh sieve) and add it to the AgNO3 solution. Ultrasonicate for 0.5 h to evenly disperse the g-C3N4 in the solution to obtain a mixed solution.

[0055] (3) Same as step (3) in Example 1; (4) Same as step (4) of Example 1.

[0056] The results are as follows Figure 6 As shown in the figure, with the addition of Ag, characteristic peaks of Ag appear in the XRD pattern, indicating that Ag atoms aggregate and are not uniformly loaded on the g-C3N4 matrix.

[0057] Comparative Example 2 A universal method for proton adsorption-induced ultrahigh surface metal single-atom loading is described. 35 wt% Ag (35 wt%-Ag / g-C3N4) single atoms are loaded on a graphene carbon nitride substrate (g-C3N4) via a one-step calcination method. The method comprises the following steps: (1) The preparation of g-C3N4 is the same as in Example 1; (2) Same as step (2) in Example 1; (3) Same as step (3) in Example 1; (4) The porcelain boat containing the sample was placed in a tube furnace and calcined under argon protection. The heating rate during the calcination process was 8 °C / min, and the temperature was raised to 550 °C. The calcination time was 1 h, and a 35 wt%-Ag / g-C3N4 single-atom catalyst was obtained.

[0058] The results are as follows Figure 6 As shown in the figure, with the addition of Ag, characteristic peaks of Ag appear in the XRD pattern, indicating that Ag atoms aggregate and are not uniformly loaded on the g-C3N4 matrix.

[0059] The results of Example 1 and Comparative Examples 1 and 2 indicate that it is difficult to prepare ultra-high-concentration single-atom catalysts without protonating the catalyst. It is also difficult to successfully prepare single-atom catalysts without removing residual water of crystallization from the sample during calcination.

[0060] Although the present invention has been described in detail through the above preferred embodiments, it should be understood that the above description is not intended to limit the present invention. After reading the above description, various modifications and substitutions of the present invention will become apparent to those skilled in the art. Therefore, the scope of protection of the present invention should be defined by the appended claims.

Claims

1. A universal method for proton adsorption-induced ultrahigh surface metal single atom loading, characterized in that: The method comprises the following steps: (S1) uniformly dispersing the support protonated by a strong acidic solution or an organic solvent in a metal salt aqueous solution to obtain an acidic mixed solution; (S2) drying the acidic mixed solution containing the carrier and the metal salt ions for a first time, grinding the mixed solution into a powder, and then drying the mixed solution for a second time; (S3) The powder is placed in a tube furnace and calcined in an inert gas atmosphere in two steps. First, the powder is kept at a constant temperature for a period of time at a low temperature to reduce the crystalline water content in the powder. The low temperature should be greater than the boiling point of water and less than the decomposition temperature of the loaded soluble metal salt. Then, the temperature is raised to a high temperature of 400-600°C and the powder is subjected to a high-temperature pyrolysis treatment to completely vaporize the mixed raw materials, thereby forming single-atom active sites on the surface of the catalytic material, and obtaining a catalytic material with ultra-high surface metal single-atom loading.

2. The universal method for proton adsorption-induced ultra-high surface metal single atom loading according to claim 1, characterized in that: In step (S1), a metal salt aqueous solution is added to a carrier that has been protonated with a strongly acidic aqueous solution or an organic solvent, and ultrasonically dispersed for 0.5 to 1 h to obtain a mixed solution.

3. The universal method for proton adsorption-induced ultra-high surface metal single atom loading according to claim 1, characterized in that: In step (S1), the acid used in the strong acid solution or organic solvent is selected from any one of nitric acid, sulfuric acid and hydrochloric acid.

4. The universal method for proton adsorption-induced ultra-high surface metal single atom loading according to claim 1, characterized in that: In step (S1), the organic solvent is selected from any one of acetone, methanol and ethanol.

5. The universal method for proton adsorption-induced ultra-high surface metal single atom loading according to claim 1, characterized in that: In step (S1), the amount of the added strong acid solution or organic solvent is 2-5 mL / g.

6. The universal method for proton adsorption-induced ultra-high surface metal single atom loading according to claim 1, characterized in that: In step (S1), the carrier is selected from any one of borides, carbides and nitrogen compounds.

7. The universal method for proton adsorption-induced ultra-high surface metal single atom loading according to claim 1, characterized in that: The metal single atom is selected from any one of calcium, chromium, manganese, iron, copper, cobalt, nickel, zinc, molybdenum, indium, lanthanum, cerium, praseodymium, gold, silver, platinum, palladium, rhodium, ruthenium, osmium, iridium and antimony.

8. The universal method for proton adsorption-induced ultra-high surface metal single atom loading according to claim 1, characterized in that: In step (S2), the first drying is to evaporate the mixed solution to dryness at 95°C; the second drying is to be carried out at 130°C; and the grinding time is 15 minutes.

9. The universal method for proton adsorption-induced ultra-high surface metal single atom loading according to claim 1, characterized in that: In step (S3), before the sample is placed in the tube furnace, an inert gas is introduced into the tube furnace for 10 to 20 minutes; the inert gas is selected from argon, helium, nitrogen or xenon; the calcination heating rate is 5 to 8 ° C / min, the low-temperature calcination time at 100 to 400 ° C is 9 hours, and the high-temperature calcination time at 400 to 600 ° C is 1 hour.

10. A catalytic material obtained by the universal method of proton adsorption-induced ultra-high surface metal single atom loading as claimed in any one of claims 1 to 9.

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