A method for preparing a p-block main group metal monatomic catalyst, and products and uses thereof
By preparing highly loaded p-block main group metal single-atom catalysts using the coordination-confinement method, the problem of metal atom aggregation in traditional methods was solved, and high catalytic activity and stability in electrocatalytic carbon dioxide reduction were achieved.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- SHANDONG UNIV
- Filing Date
- 2023-11-10
- Publication Date
- 2026-07-24
AI Technical Summary
Existing technologies make it difficult to prepare high-load p-block main group metal single-atom catalysts, and traditional methods tend to cause metal atoms to aggregate into nanoparticles or clusters, affecting catalytic activity.
A highly loaded p-block main group metal single-atom catalyst was prepared by annealing using a coordination-confinement method with dopamine hydrochloride, a nitrogen-doped carbon substrate, and a silica template to prevent metal atom migration and aggregation.
A highly loaded p-block main group metal single-atom catalyst was successfully prepared, which improved catalytic activity and stability and exhibited excellent electrocatalytic carbon dioxide reduction performance.
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Figure CN117587449B_ABST
Abstract
Description
Technical Field
[0001] This invention belongs to the field of single-atom catalyst preparation technology, specifically relating to a method for preparing p-block group metal single-atom catalysts, as well as their products and applications. Background Technology
[0002] The information disclosed in this background section is intended only to enhance understanding of the overall background of the invention and is not necessarily to be construed as an admission or in any way implying that such information constitutes prior art known to those skilled in the art.
[0003] With the increasing severity of global greenhouse effect and energy consumption, there is a great deal of interest in reducing carbon dioxide into value-added fuels and chemicals in a green and sustainable manner. Due to their unique electronic structure, single-atom catalysts supported on nitrogen-doped carbon supports typically exhibit high selectivity in electrocatalytic carbon dioxide reduction, thus attracting widespread research interest. For example, single-atom catalysts supported on d-block transition metals such as nickel (Ni), iron (Fe), cobalt (Co), and manganese (Mn) can effectively convert carbon dioxide to carbon monoxide, while single-atom catalysts supported on p-block main group metals such as indium (In), tin (Sn), and antimony (Sb) can convert carbon dioxide to formic acid. Besides product selectivity, catalytic activity is also an important factor to consider in electrocatalytic carbon dioxide reduction, especially in practical industrial applications with high current densities. The level of catalytic activity is directly related to the loading of metal sites; however, single-atom catalysts prepared by traditional pyrolysis methods typically have low loading. Reported high-loading single-atom catalysts are still limited to d-block transition metals, and reasonable synthesis methods for high-loading p-block main group metal single-atom catalysts are still lacking. Summary of the Invention
[0004] To address the shortcomings of existing technologies, the present invention aims to provide a method for preparing p-block main group metal single-atom catalysts, as well as related products and applications. In traditional impregnation pyrolysis methods, metals are physically adsorbed onto a nitrogen-doped carbon substrate. Typically, the interaction between the metal and the substrate is weak, and metal atoms tend to aggregate into nanoparticles or clusters during the pyrolysis stage. To avoid the formation of nanoparticles or clusters, the metal loading in the precursor is usually reduced; therefore, traditional impregnation pyrolysis methods are difficult to prepare high-load single-atom catalysts. The present invention uses a "coordination-confinement" method, different from traditional impregnation pyrolysis methods, to universally prepare high-load p-block main group metal (indium, tin, antimony) single-atom catalysts.
[0005] To achieve the above objectives, the present invention is implemented through the following technical solution:
[0006] In a first aspect, the present invention provides a method for preparing a p-block main group metal single-atom catalyst, comprising the following steps:
[0007] S1. Dopamine hydrochloride is dissolved in water and then reacted with tris(hydroxymethyl)aminomethane, silica template, and p-block main group metal salt to obtain the precursor.
[0008] S2. After annealing the precursor, the silica template is removed to obtain the p-block main group metal single-atom catalyst.
[0009] Preferably, in step S1, the molar ratio of dopamine hydrochloride to tris(hydroxymethyl)aminomethane is 1:1.4-1.6.
[0010] Preferably, the p-block group metal salt includes soluble salts of indium, tin, and antimony.
[0011] Preferably, step S1 specifically involves: dissolving dopamine hydrochloride in water, adding tris(hydroxymethyl)aminomethane and stirring to mix, then adding a silica template, and finally adding a p-block main group metal salt to react and obtain a precursor.
[0012] Preferably, step S1 specifically involves: dissolving dopamine hydrochloride in water and adjusting the pH to 1 with hydrochloric acid, adding a p-block group metal salt and stirring to mix, then adding tris(hydroxymethyl)aminomethane and stirring to mix, and finally adding a silica template to react and obtain the precursor.
[0013] Preferably, in step S1, the reaction time is 10-14 hours.
[0014] Preferably, in step S2, the annealing temperature is 700-800℃, the annealing time is 1.5-2.5h, and the annealing atmosphere is argon or nitrogen.
[0015] Preferably, at least one of hydrofluoric acid, sodium hydroxide, potassium hydroxide, or ammonium fluoride is used to remove the silica template.
[0016] In a second aspect, the present invention provides a p-block main group metal single-atom catalyst, which is obtained by the preparation method described in the first aspect.
[0017] Thirdly, the present invention provides the application of p-block main group metal single-atom catalysts as described in the second aspect in the electrocatalytic reduction of carbon dioxide.
[0018] The beneficial effects achieved by one or more technical solutions of the present invention are as follows:
[0019] This invention uses a "coordination-confinement" method to confine metal ions within metal-polydopamine units, which not only increases the metal loading in the precursor but also prevents metal atoms from migrating and forming nanoparticles or clusters during pyrolysis.
[0020] Using silica as a template, hollow mesoporous nitrogen-doped carbon substrates can be prepared. These substrates have a large specific surface area, provide abundant defect structures, and can provide a large number of molar positioning sites, enabling the preparation of highly loaded indium single-atom catalysts, tin single-atom catalysts, and antimony single-atom catalysts. Attached Figure Description
[0021] The accompanying drawings, which form part of this invention, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an improper limitation of the invention.
[0022] Figure 1 The images shown are (a) scanning electron microscope image, (b) spherical aberration corrected high-angle annular dark-field scanning transmission electron microscope image, and (c) elemental distribution image of In-O2N2 SACs in Example 1.
[0023] Figure 2 The images shown are (a) scanning electron microscope image, (b) spherical aberration corrected high-angle annular dark-field scanning transmission electron microscope image, and (c) elemental distribution image of In-O4 SACs in Example 2.
[0024] Figure 3 The following are the (a) K-edge XANES spectra, (b) K-edge FT-EXAFS spectra, and (c, d) corresponding EXAFS fitting curves in R space for In-O2N2 SACs in Example 1 and In-O4 SACs in Example 2.
[0025] Figure 4 XRD patterns of (A) the indium single-atom catalyst of Example 1, (B) the tin single-atom catalyst of Example 3, and (C) the antimony single-atom catalyst of Example 4;
[0026] Figure 5 Scanning electron microscope images of the indium single-atom catalyst of Example 1, the tin single-atom catalyst of Example 3, and the antimony single-atom catalyst of Example 4;
[0027] Figure 6 This is an aberration-corrected high-angle annular dark-field scanning transmission electron microscope image of the tin single-atom catalyst in Example 3.
[0028] Figure 7 In Figure a, LSV curves of In-O2N2 SACs from Example 1, In-O4 SACs from Example 2, and HMNC from Comparative Example 1 are shown. In Figure b, different products of In-O2N2 SACs from Example 1 at different voltages are shown (from top to bottom in the bar chart: HCOO). -The Faraday efficiency of (CO, H2), where c represents the different products of In-O4 SACs in Example 2 at different voltages (from top to bottom in the bar chart: HCOO). - The Faraday efficiency of (CO, H2) is shown in the figure, and d is the stability test result of In-O2N2 SACs in Example 1. Detailed Implementation
[0029] To enable those skilled in the art to better understand the technical solution of the present invention, the technical solution of the present invention will be described in detail below with reference to specific embodiments and comparative examples.
[0030] Example 1
[0031] Dissolve 1.79 g of dopamine hydrochloride in 600 mL of deionized water, and add 1.7 g of tris(hydroxymethyl)aminomethane while stirring. Then, disperse 1.09 g of silica in 100 mL of water and add it to the reaction system. After stirring for 20 min, add 10 mL of 0.1 mol / L In... 3+ The solution was stirred and reacted for 12 hours. The reaction system was centrifuged, the precipitate was washed, and dried at 50°C to obtain the precursor. The precursor was annealed at 750°C for 2 hours in an argon atmosphere. After annealing, it was first etched with 2.25M NaOH solution at 65°C for 18 hours to remove the silica template, and then etched with 1M HCl for 36 hours to obtain the indium single-atom catalyst, denoted as In-O2N2 SACs. Figure 1 As shown in Figure A, the microstructure of In-O2N2 SACs is hollow spheres, and no obvious metal nanoparticles or clusters were observed. Figure 1 As shown in b, no metal nanoparticles or clusters were found, proving that the metal sites in In-O2N2 SACs are dispersed in a single-atom state. Figure 1 As shown in c, the In, C, N and O elements are evenly distributed in In-O2N2 SACs, with a high In content. The In content in In-O2N2 SACs was 13.02 wt% as determined by ICP testing.
[0032] Example 2
[0033] Dissolve 1.79 g of dopamine hydrochloride in 600 mL of deionized water and adjust the pH of the solution to 1 with hydrochloric acid. Add 10 mL of 0.1 mol / L In solution while stirring. 3+The solution was stirred for 1 hour, and then 1.7 g of tris(hydroxymethyl)aminomethane was added. 1.09 g of silica was dispersed in 100 mL of water and added to the reaction system, and the mixture was stirred for 12 hours. The reaction system was centrifuged, the precipitate was washed, and dried at 50 °C to obtain the precursor. The precursor was annealed at 750 °C for 2 hours in an argon atmosphere. After annealing, it was first etched with 2.25 M NaOH solution at 65 °C for 18 hours to remove the silica subtemplate, and then etched with 1 M HCl for 36 hours to obtain the indium single-atom catalyst, denoted as In-O4SACs. Figure 2 As shown in Figure A, the microstructure of In-O4 SACs is hollow spheres, and no obvious metal nanoparticles or clusters were observed. Figure 2 As shown in b, no metal nanoparticles or clusters were found, proving that the metal sites in In-O4 SACs are dispersed in a single-atom state. Figure 2 As shown in c, In-O4 SACs have a uniform distribution of In, C, N and O elements, with a high In content. The In content in In-O4 SACs was 9.89 wt% as determined by ICP testing.
[0034] like Figure 3 As shown, no obvious In-In metallic bonds were found in either In-O2N2 SACs or In-O4 SACs, proving that the indium element is dispersed in a single-atom state in the prepared indium single-atom catalyst. In In-O2N2 SACs, each indium atom is coordinated with two nitrogen atoms and two oxygen atoms, while in In-O4 SACs, each indium atom is coordinated with four oxygen atoms.
[0035] Example 3
[0036] Unlike Example 1, In 3+ The solution was replaced with an equal volume of Sn of equimolar concentration. 4+ O solution yields tin single-atom catalyst.
[0037] Example 4
[0038] Unlike Example 1, In 3+ The solution was replaced with an equal volume of Sb of equimolar concentration. 3+ Antimony single-atom catalysts were obtained from the solution.
[0039] like Figure 4 As shown, no obvious peaks related to metal nanoparticles and metal oxides were observed in any of the three p-block main group metal single-atom catalysts. Figure 5 As shown, all three p-block main group metal single-atom catalysts exhibited a mesoporous hollow nitrogen-doped carbon substrate morphology, and no obvious metal nanoparticles or clusters were observed. Figure 6 As shown, no metal nanoparticles or clusters were found in the tin single-atom catalyst.
[0040] Comparative Example 1
[0041] Unlike Example 1, In is not added. 3+ The solution yielded a final product denoted as HMNC.
[0042] Example 5
[0043] The In-O2N2 SACs from Example 1, the In-O4 SACs from Example 2, and the HMNC from Comparative Example 1 were prepared as inks and dropped onto hydrophobic carbon paper to serve as cathodes in a three-electrode electrolytic cell for electrocatalytic carbon dioxide reduction experiments. The electrolyte was CO2-saturated 0.5M KHCO3, and the loading was 1.6 mg / cm³ for all samples. -2 .
[0044] like Figure 7 As shown in Figure a, compared to the bare HMNC, the two In SACs exhibit lower onset potentials and higher total current densities, in the order In-O2N2 SACs > In-O4 SACs, indicating their potential CO2RR performance. Figure 7 As shown in b, the formate formation Faraday efficiency (FE) of In-O2N2 SACs. HCOO- It can maintain >90% within a wide potential window from -0.7 to -1.1V, and reaches a maximum of 95.5% at -0.8V. Figure 7 As shown in c, In-O4 SACs exhibit a low FE over a total potential range of -0.7 to -1.1 V. HCOO- The maximum FE at -0.9V HCOO- Approximately 64%. For example... Figure 7 As shown in d, In-O2N2 SACs were tested at -0.8V vs RHE for 24 hours without a significant decrease in current density, and at the end of the evaluation, FE HCOO- Maintaining >95% durability confirms the high durability of In-O2N2 SACs.
[0045] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.
Claims
1. A method for preparing a p-block main group metal single-atom catalyst, characterized in that, Includes the following steps: S1. Dopamine hydrochloride is dissolved in water and then reacted with tris(hydroxymethyl)aminomethane, silica template, and p-block main group metal salt to obtain the precursor. S2. After annealing the precursor, the silica template is removed to obtain the p-block main group metal single-atom catalyst. The annealing temperature is 700-800 ℃, the annealing time is 1.5-2.5 h, and the annealing atmosphere is argon. The p-block group metal salts include soluble salts of indium, tin, and antimony.
2. The preparation method according to claim 1, characterized in that, In step S1, the molar ratio of dopamine hydrochloride to tris(hydroxymethyl)aminomethane is 1:1.4-1.
6.
3. The preparation method according to claim 1, characterized in that, Step S1 specifically involves dissolving dopamine hydrochloride in water, adding tris(hydroxymethyl)aminomethane and stirring, then adding a silica template, and finally adding a p-block main group metal salt to obtain the precursor.
4. The preparation method according to claim 1, characterized in that, Step S1 is as follows: Dopamine hydrochloride is dissolved in water and hydrochloric acid is added to adjust the pH to 1. Then, a p-block main group metal salt is added and stirred to mix. Tris(hydroxymethyl)aminomethane is added and stirred to mix. Finally, a silica template is added to react and obtain the precursor.
5. The preparation method according to claim 1, characterized in that, In step S1, the reaction time is 10-14 h.
6. The preparation method according to claim 1, characterized in that, Use at least one of hydrofluoric acid, sodium hydroxide, potassium hydroxide, or ammonium fluoride to remove the silica template.
7. A p-block group metal single-atom catalyst, characterized in that, Obtained by the preparation method as described in any one of claims 1-6.
8. The application of the p-block main group metal single-atom catalyst as described in claim 7 in electrocatalytic carbon dioxide reduction.