An ORR non-noble metal single-atom catalyst and its preparation method

Abstract

An ORR non-noble metal single-atom catalyst and its preparation method, which relates to the technical field of catalysts, solves the problem that non-noble metal single-atom sites are prone to agglomeration, resulting in poor stability of the catalyst, and can be applied to the ORR process of fuel cells. Dispersing metal salts in a suspension of basic zinc carbonate and stirring to make it evenly dispersed; centrifuging the suspension to remove the supernatant; adding the centrifuged product, melamine and glucose to deionized water for mixing and continuing to stir; centrifuging again to remove the supernatant, collecting the product, drying it in an oven to obtain a catalyst precursor; placing the catalyst precursor in a tube furnace and calcining it under a nitrogen atmosphere; grinding the calcined product, then pickling, filtering by suction and drying; performing a second calcination on the product in step S6, collecting the product, and drying it to obtain the target catalyst.

Description

Technical Field

[0001] The present invention relates to the technical field of catalysts, and particularly relates to an ORR non-precious metal single-atom catalyst and a preparation method thereof. Background Art

[0002] ORR (oxygen reduction reaction) is one of the essential half-reactions in new energy storage and conversion systems such as fuel cells and metal-air batteries. However, the ORR has many electron transfer steps, slow speed, and low mass transfer efficiency, resulting in slow kinetics and greatly hindering its application in actual devices. Therefore, it is necessary to develop efficient ORR catalysts.

[0003] Metal single-atom catalysts have attracted close attention due to their unique surface and interface effects, quantum size effects, and macroscopic quantum tunneling effects at the nanoscale. ORR non-precious metal single-atom catalysts have the following advantages: (1) maximizing the utilization rate of metal atoms, approaching 100%; (2) highly dispersed metal atoms, promoting the exposure of active sites; (3) having relatively uniform active centers; (4) good chemical stability, excellent electrical conductivity, large specific surface area, adjustable porous structure, and low preparation cost.

[0004] However, a large number of studies have shown that the activity and stability of ORR non-precious metal catalysts are extremely susceptible to the dispersion degree of non-precious metal single atoms, the defect structure, morphology, and surface state around the active sites. When single-atom sites agglomerate to form nanoparticles, it will lead to a reduction in the number of active sites of the catalyst, a decrease in activity, and cause the Fenton effect, making the stability of the catalyst poor. Therefore, how to efficiently prepare an ORR non-precious metal single-atom catalyst with uniform size and uniform distribution of active sites has become an important research topic in this field. Summary of the Invention

[0005] In order to solve the problem that the easy agglomeration of non-precious metal single-atom sites leads to poor stability of the catalyst, the present invention proposes an ORR non-precious metal single-atom catalyst and a preparation method thereof.

[0006] The technical solution of the present invention is as follows:

[0007] A preparation method of an ORR non-precious metal single-atom catalyst, comprising the following steps:

[0008] S1. Disperse a metal salt in a suspension of zinc basic carbonate and stir to make it uniformly dispersed;

[0009] S2. Centrifuge the suspension to remove the supernatant;

[0010] S3. Add the centrifuged product, melamine, and glucose to deionized water for mixing and continue stirring;

[0011] S4. Centrifuge again to remove the supernatant, collect the product, and dry it in an oven to obtain the catalyst precursor;

[0012] S5. Place the catalyst precursor in a tubular furnace and calcine it under a nitrogen atmosphere;

[0013] S6. Grind the calcined product, then wash it with acid, filter it by suction, and dry it;

[0014] S7. Conduct a second calcination on the product in step S6, collect the product, and dry it to obtain the target catalyst.

[0015] Preferably, the non-noble metal salt in step S1 is a chloride, sulfate, nitrate, acetate, acetylacetonate, or phosphate of iron, cobalt, nickel, copper, manganese, or chromium.

[0016] Preferably, the stirring time in both step S1 and step S3 is 6 h to 18 h.

[0017] Preferably, the mass ratio of melamine, glucose, and basic zinc carbonate is 1:2:2, and the stirring speed is 300 rpm to 800 rpm.

[0018] Preferably, the molar ratio of the metal ions in the metal salt to the Zn ions in basic zinc carbonate is 1:30.

[0019] Preferably, the heating rate of the calcination in step S5 is 2 °C / min to 15 °C / min, the calcination temperature is 900 °C to 1100 °C, and the calcination time is 2 h to 3 h.

[0020] Preferably, the acid washing in step S6 uses 0.5 mol / L to 2 mol / L HCl, the temperature of the acid washing is 50 °C to 80 °C, and the acid washing time is 6 h to 18 h.

[0021] Preferably, the drying time in both step S4 and step S6 is 6 h to 18 h.

[0022] Preferably, the heating rate of the calcination in step S7 is 2 °C / min to 15 °C / min, the calcination temperature is 900 °C to 1100 °C, the calcination time is 10 min to 60 min, and the calcination atmosphere is NH3.

[0023] The present invention also provides an ORR non-noble metal single-atom catalyst prepared by the above preparation method.

[0024] Compared with the prior art, the present invention solves the problem that the non-noble metal single-atom sites are prone to agglomeration, resulting in poor catalyst stability. The specific beneficial effects are as follows:

[0025] 1. The ORR metal single-atom catalyst provided by the present invention has a flaky morphology, a large specific surface area, a high site density, uniform distribution of active sites, no metal particles and metal agglomeration, and exhibits excellent stability;

[0026] 2. The preparation method provided by the present invention uses Zn atoms to separate Fe atoms, making it easier for Fe to form single active sites during the synthesis of the catalyst, avoiding the formation of Fe clusters and nanoparticles. At the same time, the carbon dioxide generated during the decomposition of zinc carbonate hydroxide can further adjust its morphology and enhance its mass transfer performance;

[0027] 3. The preparation method of the non-precious metal single-atom catalyst provided by the present invention is simple and environmentally friendly, suitable for large-scale industrial production, and lays a foundation for the large-scale preparation of non-precious metal single-atom catalysts. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 Transmission electron microscope image of the catalyst in Example 1 at a scale of 20 nm;

[0029] Figure 2 Pore size distribution diagram of the non-precious metal single-atom catalyst in Example 1;

[0030] Figure 3 X-ray diffraction pattern of the non-precious metal single-atom catalyst in Example 1;

[0031] Figure 4 LSV curve of the non-precious metal single-atom catalyst in Example 1. DETAILED DESCRIPTION OF THE INVENTION

[0032] To make the technical solutions of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the accompanying drawings of the present invention. It should be noted that the following embodiments are only used to better understand the technical solutions of the present invention and should not be construed as a limitation of the present invention.

[0033] Example 1.

[0034] At room temperature, 0.0132 g of ferric chloride hexahydrate was dispersed in a suspension formed by 1.2 g of zinc carbonate hydroxide, and stirred for 12 h to make it evenly dispersed;

[0035] The suspension was centrifuged to remove excess metal ions in the supernatant;

[0036] The product collected by centrifugation was added to deionized water, 0.6 g of melamine and 1.2 g of glucose were added, and stirring was continued for 12 h;

[0037] Centrifuged again to remove the supernatant, the product was collected and dried in an oven for 12 h;

[0038] Place the dried product in a tubular furnace and calcine it at 950 °C for 2 h under a nitrogen atmosphere;

[0039] Collect the product, grind it, and pickle it with 1 mol / L HCl at 60 °C for 12 h, then filter it by suction and dry it;

[0040] Conduct a second high-temperature treatment on the dried product. Calcinate it at 900 °C for 20 min in an NH3 atmosphere. Collect the product to obtain the target catalyst.

[0041] Example 2.

[0042] At room temperature, disperse 0.0108 g of anhydrous ferric chloride in the suspension formed by zinc hydroxycarbonate and stir for 12 h to make it evenly dispersed;

[0043] Centrifuge the suspension to remove the excess metal ions in the supernatant;

[0044] Add the product collected by centrifugation to deionized water, add melamine and glucose, and continue stirring for 12 h;

[0045] Centrifuge again to remove the supernatant, collect the product, and dry it in an oven for 12 h;

[0046] Place the dried product in a tubular furnace and calcine it at 950 °C for 2 h under a nitrogen atmosphere;

[0047] Collect the product, grind it, and pickle it with 1 mol / L HCl at 60 °C for 12 h, then filter it by suction and dry it;

[0048] Conduct a second high-temperature treatment on the dried product. Calcinate it at 900 °C for 20 min in an NH3 atmosphere. Collect the product to obtain the target catalyst.

[0049] Example 3.

[0050] At room temperature, disperse 0.0108 g of anhydrous ferric chloride in the suspension formed by 1.2 g of zinc hydroxycarbonate and stir for 12 h to make it evenly dispersed;

[0051] Centrifuge the suspension to remove the excess metal ions in the supernatant;

[0052] Add the product collected by centrifugation to deionized water, add 0.6 g of melamine and 1.2 g of glucose, and continue stirring for 12 h;

[0053] Centrifuge again to remove the supernatant, collect the product, and dry it in an oven for 12 h;

[0054] Place the dried product in a tubular furnace and calcine it at 1000 °C for 2 h under a nitrogen atmosphere;

[0055] Collect the product, grind it, and pickle it with 1 mol / L HCl at 80 °C for 12 h, then carry out suction filtration and drying;

[0056] Conduct a second high-temperature treatment on the dried product, and calcine it at 900 °C for 10 min in an NH₃ atmosphere. Collect the product to obtain the target catalyst.

[0057] Example 4.

[0058] At room temperature, disperse 0.0269 g of iron nitrate in the suspension formed by 1.2 g of basic zinc carbonate, and stir for 12 h to make it evenly dispersed;

[0059] Centrifuge the suspension to remove the excess metal ions in the supernatant;

[0060] Add the product collected by centrifugation to deionized water, add 0.6 g of melamine and 1.2 g of glucose, and continue stirring for 20 h;

[0061] Centrifuge again to remove the supernatant, collect the product, and place it in an oven to dry for 12 h;

[0062] Place the dried product in a tube furnace and calcine it at 950 °C for 3 h in a nitrogen atmosphere;

[0063] Collect the product, grind it, and pickle it with 1 mol / L HCl at 60 °C for 12 h, then carry out suction filtration and drying;

[0064] Conduct a second high-temperature treatment on the dried product, and calcine it at 1000 °C for 10 min in an NH₃ atmosphere. Collect the product to obtain the target catalyst.

[0065] Example 5.

[0066] At room temperature, disperse 0.0235 g of iron acetylacetonate in the suspension formed by 1.2 g of basic zinc carbonate, and stir for 12 h to make it evenly dispersed;

[0067] Centrifuge the suspension to remove the excess metal ions in the supernatant;

[0068] Add the product collected by centrifugation to deionized water, add 0.6 g of melamine and 1.2 g of glucose, and continue stirring for 12 h;

[0069] Centrifuge again to remove the supernatant, collect the product, and place it in an oven to dry for 12 h;

[0070] Place the dried product in a tube furnace and calcine it at 950 °C for 3 h in a nitrogen atmosphere;

[0071] Collect the product, grind it, and pickle it with 1 mol / L HCl at 80 °C for 12 h, then filter it by suction and dry it;

[0072] Conduct a second high-temperature treatment on the dried product, and calcine it at 900 °C for 20 min in an NH3 atmosphere. Collect the product to obtain the target catalyst.

[0073] Example 6.

[0074] At room temperature, disperse 0.0086 g of cobalt chloride in a suspension formed by 1.2 g of basic zinc carbonate, and stir for 12 h to make it evenly dispersed;

[0075] Centrifuge the suspension to remove the excess metal ions in the supernatant;

[0076] Add the product collected by centrifugation to deionized water, add 0.6 g of melamine and 1.2 g of glucose, and continue stirring for 12 h;

[0077] Centrifuge again to remove the supernatant, collect the product, and dry it in an oven for 12 h;

[0078] Place the dried product in a tubular furnace and calcine it at 1000 °C for 2 h in a nitrogen atmosphere;

[0079] Collect the product, grind it, and pickle it with 1 mol / L HCl at 80 °C for 12 h, then filter it by suction and dry it;

[0080] Conduct a second high-temperature treatment on the dried product, and calcine it at 950 °C for 10 min in an NH3 atmosphere. Collect the product to obtain the target catalyst.

[0081] Example 7.

[0082] At room temperature, disperse 0.0166 g of cobalt acetate in a suspension formed by 1.2 g of basic zinc carbonate, and stir for 12 h to make it evenly dispersed;

[0083] Centrifuge the suspension to remove the excess metal ions in the supernatant;

[0084] Add the product collected by centrifugation to deionized water, add 0.6 g of melamine and 1.2 g of glucose, and continue stirring for 12 h;

[0085] Centrifuge again to remove the supernatant, collect the product, and dry it in an oven for 12 h;

[0086] Place the dried product in a tubular furnace and calcine it at 950 °C for 2 h in a nitrogen atmosphere;

[0087] Collect the product, grind it, and pickle it with 1 mol / L HCl at 80 °C for 12 h, then filter it by suction and dry it;

[0088] The dried product is subjected to a second high-temperature treatment, calcined at 900 °C for 30 min in an NH3 atmosphere. The target catalyst is obtained by collecting the product.

[0089] Example 8.

[0090] At room temperature, 0.0121 g of cobalt nitrate is dispersed in a suspension formed by 1.2 g of basic zinc carbonate, and stirred for 12 h to make it evenly dispersed;

[0091] The suspension is centrifuged to remove the excess metal ions in the supernatant;

[0092] The product collected by centrifugation is added to deionized water, 0.6 g of melamine and 1.2 g of glucose are added, and stirring is continued for 12 h;

[0093] Centrifuge again to remove the supernatant, collect the product, and place it in an oven to dry for 12 h;

[0094] The dried product is placed in a tubular furnace and calcined at 950 °C for 3 h in a nitrogen atmosphere;

[0095] Collect the product, grind it, and pickle it with 1 mol / L HCl at 60 °C for 12 h, then filter by suction and dry;

[0096] The dried product is subjected to a second high-temperature treatment, calcined at 950 °C for 10 min in an NH3 atmosphere. The target catalyst is obtained by collecting the product.

[0097] Example 9.

[0098] At room temperature, 0.0173 g of cobalt acetylacetonate is dispersed in a suspension formed by 1.2 g of basic zinc carbonate, and stirred for 12 h to make it evenly dispersed;

[0099] The suspension is centrifuged to remove the excess metal ions in the supernatant;

[0100] The product collected by centrifugation is added to deionized water, 0.6 g of melamine and 1.2 g of glucose are added, and stirring is continued for 12 h;

[0101] Centrifuge again to remove the supernatant, collect the product, and place it in an oven to dry for 12 h;

[0102] The dried product is placed in a tubular furnace and calcined at 1100 °C for 2 h in a nitrogen atmosphere;

[0103] Collect the product, grind it, and pickle it with 1 mol / L HCl at 80 °C for 12 h, then filter by suction and dry;

[0104] The dried product was subjected to a second high-temperature treatment and calcined in an NH3 atmosphere at 900 °C for 10 min. The target catalyst was obtained by collecting the product.

[0105] Effect example.

[0106] The non-precious metal single-atom catalyst of Example 1 was analyzed by transmission electron microscopy, and the results are shown in Figure 1 As shown, it can be seen that the catalyst has a flaky structure and a large specific surface area.

[0107] The pore size distribution of the non-precious metal single-atom catalyst of Example 1 was tested, and the results are shown in Figure 2 As shown, combined with the adsorption-desorption isotherm and fitted by the BET equation, the surface area and pore size distribution data of the Fe-N-C catalyst were obtained. The specific surface area of the Fe-N-C catalyst is 1347 m 2 / g. A large number of micropores can be observed in the pore size distribution curve of the Fe-N-C catalyst, and the presence of a large number of micropores helps to expose the active sites.

[0108] The non-precious metal single-atom catalyst of Example 1 was analyzed by X-ray, and the results are shown in Figure 3 As shown, in the XRD pattern, no peaks of Fe oxides and clusters appeared, confirming the monodispersed characteristics of the Fe sites.

[0109] The non-precious metal single-atom catalyst of Example 1 was subjected to electrochemical testing, and the results are shown in Figure 3 As shown, the half-wave potential of the Fe-N-C catalyst is 0.89 V, showing excellent oxygen reduction reaction activity.

[0110] The transmission electron microscopy images of the non-precious metal single-atom catalysts in Examples 2-9 were observed, and the results were similar to those of Example 1. The presence of particles was not observed, confirming that the Fe sites exist in a monodispersed form in the Fe-N-C catalyst.

[0111] Obviously, the above embodiments are merely examples for clear illustration, and other forms of changes or variations can be made on the basis of the above description. Therefore, the obvious changes or variations derived therefrom still fall within the protection scope of the present invention.

Claims

1. A preparation method of an ORR non-noble metal single-atom catalyst, characterized in that, It includes the following steps: S1. Disperse the metal salt in the suspension of basic zinc carbonate and stir to make it evenly dispersed; S2. Centrifuge the suspension and remove the supernatant; S3. Add the centrifuged product, melamine and glucose into deionized water for mixing and continue stirring; S4. Centrifuge again to remove the supernatant, collect the product, place it in an oven to dry, and obtain the catalyst precursor; S5. Place the catalyst precursor in a tubular furnace and calcine it under a nitrogen atmosphere; S6. Grind the calcined product, then wash it with acid, filter it by suction and dry it; S7. Conduct a second calcination on the product in step S6, collect the product, and dry it to obtain the target catalyst.

2. The preparation method of the ORR non-noble metal single-atom catalyst according to claim 1, characterized in that, The metal salt described in step S1 is chloride, sulfate, nitrate, acetate, acetylacetonate or phosphate of iron, cobalt, nickel, copper, manganese or chromium.

3. The preparation method of the ORR non-precious metal single-atom catalyst according to claim 1, characterized in that, The stirring time in both step S1 and step S3 is 6h to 18h.

4. The preparation method of the ORR non-noble metal single-atom catalyst according to claim 1, characterized in that, The mass dosage ratio of melamine, glucose and basic zinc carbonate is 1:2:2, and the stirring speed is 300rpm to 800rpm.

5. The preparation method of the ORR non-noble metal single-atom catalyst according to claim 1, wherein, The molar ratio of the metal ions in the metal salt to the Zn ions in basic zinc carbonate is 1:

30.

6. The preparation method of the ORR non-noble metal single-atom catalyst according to claim 1, characterized in that, In step S5, the heating rate of the calcination is 2°C / min to 15°C / min, the calcination temperature is 900°C to 1100°C, and the calcination time is 2h to 3h.

7. The preparation method of the ORR non-precious metal single-atom catalyst according to claim 1, wherein In step S6, the acid washing uses 0.5mol / L to 2mol / L HCl, the temperature of the acid washing is 50°C to 80°C, and the acid washing time is 6h to 18h.

8. The preparation method of the ORR non-noble metal single-atom catalyst according to claim 1, characterized in that, The drying time in both step S4 and step S6 is 6h to 18h.

9. The preparation method of the ORR non-precious metal single-atom catalyst according to claim 1, characterized in that, In step S7, the heating rate of the calcination is 2°C / min to 15°C / min, the calcination temperature is 900°C to 1100°C, the calcination time is 10min to 60min, and the calcination atmosphere is NH3.

10. An ORR non-noble metal single-atom catalyst, characterized in that, Prepared by the preparation method described in any one of claims 1 to 9.

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