A supported Pt-Au heteronuclear diatomic catalyst, its preparation method and application
By using 1,6-hexanediamine as a directing agent, a supported Pt-Au heteronuclear diatomic catalyst was prepared, which solved the problem of uneven distribution in the synthesis of heteronuclear diatomic catalysts, and achieved the effect of highly efficient electrocatalytic reduction of nitrate to ammonia, simplifying the preparation process and reducing costs.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- INNER MONGOLIA UNIVERSITY
- Filing Date
- 2024-12-27
- Publication Date
- 2026-06-02
AI Technical Summary
Existing technologies make it difficult to accurately synthesize high proportions of heteronuclear diatomic catalysts, resulting in uneven distribution of diatomic sites in the catalyst. Furthermore, the synthesis process relies on expensive equipment and rare metal complexes, making large-scale preparation difficult.
Using 1,6-hexanediamine as a diatomic structure guide and stabilizer, a supported Pt-Au heteronuclear diatomic catalyst was prepared in two steps. First, Pt atoms were loaded onto g-C3N4, and then Au atoms were introduced under the guidance of 1,6-hexanediamine, so as to achieve precise controlled dispersion of platinum single atoms and avoid unwanted pairing.
The prepared supported Pt-Au heteronuclear diatomic catalyst exhibits high ammonia yield and good electrochemical stability in the electrocatalytic reduction of nitrate to ammonia, with an ammonia yield as high as 3347.6 μg h⁻¹ mg⁻¹ and a Faraday efficiency of 96%, which simplifies the preparation process and reduces costs.
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Abstract
Description
Technical Field
[0001] This application relates to a supported Pt-Au heteronuclear diatomic catalyst, its preparation method and application, belonging to the field of electrocatalytic nitrate reduction to ammonia technology. Background Technology
[0002] Ammonia is an essential chemical for human survival and ecosystems, and is considered a key alternative fuel for green hydrogen and a crucial carrier for energy transition. Currently, ammonia synthesis mainly relies on the energy-intensive and carbon-intensive Haber-Bosch (HB) process, which uses nitrogen obtained from air separation and hydrogen obtained from fossil fuel reforming as feedstocks under high temperature and pressure conditions, resulting in significant carbon emissions and energy consumption. Electrocatalytic nitrate reduction reaction (e-NO3RR) enables large-scale ammonia production under environmentally friendly conditions while mitigating nitrate pollution, providing a dual benefit of "turning waste into treasure." However, the synthesis of ammonia via electrocatalytic nitrate reduction involves complex electron transfer processes and is subject to competition from the hydrogen evolution reaction. Therefore, designing highly selective electrocatalytic nitrate reduction catalysts has become a key challenge.
[0003] Diatom catalysts (DACs) have attracted widespread attention in the field of catalysis due to their high atom utilization and synergistic catalytic effect between two atomic sites. Compared with single-atom catalysts, DACs have higher metal loading, flexible combinations of multiple metal atoms, and unique microenvironments, exhibiting superior catalytic performance in many reactions. The advantages of increased metal atom number, the regulation of adsorption configuration of reactants and intermediates by the interaction between the two atoms, the synergistic effect between metal atoms and / or supports, and the reduction of reaction barriers have made them a hot research topic in the field of electrocatalytic nitrate reduction to ammonia.
[0004] In the synthesis of most DACs in the past, the lack of correlation between the two metal sites and the high randomness of their pairing led to a random and uncontrollable distribution of the two metal sites, resulting in a relatively low proportion of diatomic sites in the obtained catalysts. Single atoms, clusters, and nanoparticles also coexisted. This is particularly problematic in the precise synthesis of heteronuclear diatomic catalysts, where the formation of homonuclear diatomic clusters further complicates the process. Current methods for preparing heteronuclear DACs, such as wet chemical impregnation and atomic layer deposition (ALD), can precisely prepare diatomic sites, but their limited "precision engineering" capabilities result in structural inhomogeneity, making it difficult to accurately distinguish between target diatomic pairs and densely packed atoms. Furthermore, these methods largely rely on expensive equipment and rare dinuclear metal complexes. Currently, there is a lack of simple and universal methods in the field of heteronuclear DAC synthesis for the precise and large-scale synthesis of stable heteronuclear diatomic catalysts with a high proportion of diatomic distributions. Summary of the Invention
[0005] To address the aforementioned technical problems, this application provides a preparation method for a supported Pt-Au heteronuclear diatomic catalyst, using 1,6-hexanediamine (HA) as a diatomic structure directing and stabilizing agent, exhibiting a well-defined diatomic configuration. The preparation method is simple, independent of metal precursors and specialized equipment, and enables large-scale preparation of diatomic catalysts. The prepared supported Pt-Au heteronuclear diatomic catalyst exhibits superior ammonia synthesis performance and demonstrates excellent electrochemical stability.
[0006] The technical solution adopted in this application is as follows:
[0007] According to a first aspect of this application, a method for preparing a supported Pt-Au heteronuclear diatomic catalyst is provided, comprising the following steps:
[0008] S1. Calcining urea yields g-C3N4 powder;
[0009] S2. Add water and the g-C3N4 powder to the aqueous solution of H2PtCl6 to obtain mixture I. Stir the mixture I, remove the solvent, dry the product and then calcine it II to obtain Pt1 / g-C3N4.
[0010] S3. Add 1,6-hexanediamine aqueous solution to the aqueous dispersion containing Pt1 / g-C3N4, stir II, then add HAuCl4 aqueous solution to obtain mixture II, stir mixture II, remove solvent, dry the product and calcine III to obtain the supported Pt-Au heteronuclear diatomic catalyst.
[0011] The addition of 1,6-hexanediamine serves as a diatomic structure directing agent and stabilizer.
[0012] Optionally, in step S1, the conditions for calcination I include: a heating rate of 4℃ / min to 6℃ / min, a calcination temperature of 400℃ to 600℃, and a calcination time of 3h to 5h.
[0013] Optionally, in step S2, the concentration of the aqueous solution of H2PtCl6 is 0.05M to 0.25M.
[0014] Optionally, in step S2, the ratio of the amount of g-C3N4 powder to the aqueous solution of H2PtCl6 and water is 0.5g: 100μL~200μL: 100mL~150mL.
[0015] Optionally, in step S2, the conditions for calcination II include: a heating rate of 4℃ / min to 6℃ / min, a calcination temperature of 200℃ to 400℃, and a calcination time of 1h to 3h.
[0016] Optionally, in step S2, the stirring time is 12h to 36h.
[0017] Optionally, in step S3, the concentration of the 1,6-hexanediamine aqueous solution is 0.05M to 0.25M.
[0018] In this application, 1,6-hexanediamine acts as a diatomic structure directing agent and stabilizer.
[0019] Optionally, in step S3, the volume ratio of the aqueous dispersion of Pt1 / g-C3N4 to the aqueous solution of 1,6-hexanediamine is 25 mL: 50 μL to 100 μL.
[0020] Optionally, in step S3, the concentration of the HAuCl4 aqueous solution is 0.05M to 0.25M.
[0021] Optionally, in step S3, the volume ratio of the aqueous dispersion of Pt1 / g-C3N4 to the aqueous solution of HAuCl4 is 25 mL: 10 μL to 50 μL.
[0022] Optionally, in steps S2 and S3, the conditions for removing the solvent independently include: heating at 60°C to 80°C until the solvent is completely evaporated.
[0023] Optionally, in steps S2 and S3, the drying conditions independently include: a drying temperature of 60°C to 80°C and a drying time of 6h to 18h.
[0024] Optionally, in step S3, the conditions for calcination III include: under an inactive atmosphere, a heating rate of 4℃ / min to 6℃ / min, a calcination temperature of 100℃ to 300℃, and a calcination time of 0.5h to 2h.
[0025] Optionally, in step S3, the stirring time for stirring II is 0.5h to 2h.
[0026] Optionally, in step S3, the stirring time for stirring II is 12h to 36h.
[0027] According to a first aspect of this application, a supported Pt-Au heteronuclear diatomic catalyst prepared by the above-described preparation method is provided, wherein platinum atoms and gold atoms are arranged in pairs on the supported Pt-Au heteronuclear diatomic catalyst.
[0028] According to a first aspect of this application, a supported Pt-Au heteronuclear diatomic catalyst prepared by the above-described preparation method or the above-described supported Pt-Au heteronuclear diatomic catalyst is provided for the reduction of nitrate to ammonia.
[0029] The beneficial effects that this application can produce include:
[0030] (1) The preparation method of the supported Pt-Au heteronuclear diatomic catalyst provided in this application uses 1,6-hexanediamine for the precise synthesis of heteronuclear diatoms. The amino groups at both ends of the hexanediamine molecule pair the two heteronuclear diatoms through complexation and restrict the movement of the two atoms in space during the thermal decomposition process, guiding them to form a diatomic configuration on the g-C3N4 substrate, thereby achieving the purpose of precise synthesis of the supported Pt-Au heteronuclear diatomic catalyst.
[0031] (2) The preparation method provided in this application employs a two-step method to introduce two atoms: firstly, the first atom Pt is loaded into the defect of g-C3N4, and then the second metal atom Au is introduced under the guidance of 1,6-hexanediamine. This method can achieve precise control and dispersion of platinum single atoms by independently optimizing the reaction conditions, avoiding uncertain reactions or undesirable pairings caused by the simultaneous introduction of two metal atoms.
[0032] (3) The preparation method provided in this application is simple, does not depend on metal precursors and special instruments, has mild reaction conditions, and can realize the large-scale preparation of heteronuclear diatomic catalysts.
[0033] (4) The Pt-Au heteronuclear diatomic particles prepared by the method provided in this application can be used as a catalyst for the electrocatalytic reduction of nitrate to ammonia, with an ammonia yield as high as 3347.6 μg / h. -1 mg -1 It has a Faraday efficiency of 96%, which is better than most single-atom / diatomic catalysts reported to date. Attached Figure Description
[0034] Figure 1 For the purpose of applying for aberration-corrected high-angle annular dark-field scanning transmission microscope image of the supported Pt-Au heteronuclear diatomic catalyst prepared in Example 1 of this invention;
[0035] Figure 2 The X-ray diffraction pattern of the supported Pt-Au heteronuclear diatomic catalyst prepared in Example 1 of this application;
[0036] Figure 3The images show the near-edge X-ray absorption fine structure spectra of the supported Pt-Au heteronuclear diatomic catalyst prepared in Example 1 of this application, where a is the normalized Pt L3 edge X-ray absorption near-edge structure spectrum of the supported Pt-Au heteronuclear diatomic catalyst in Example 1 of this application, and b is the normalized Au L3 edge X-ray absorption near-edge structure spectrum of the supported Pt-Au heteronuclear diatomic catalyst in Example 1 of this application.
[0037] Figure 4 This is a schematic diagram showing the ammonia yield and Faraday efficiency at different potentials in the electrocatalytic reduction of nitrate to ammonia performance test of the Pt-Au heteronuclear diatomic catalyst prepared in Example 1 of this application.
[0038] Figure 5 This is a cyclic schematic diagram of the electrocatalytic nitrate reduction to ammonia production performance of the supported Pt-Au heteronuclear diatomic catalyst prepared in Example 1 of this application. Detailed Implementation
[0039] The present application is described in detail below with reference to the embodiments, but the present application is not limited to these embodiments.
[0040] Unless otherwise specified, all raw materials used in the embodiments of this application were purchased through commercial channels.
[0041] Unless otherwise specified, all test methods are standard and all instrument settings are those recommended by the manufacturer.
[0042] Example 1: Preparation of Supported Pt-Au Heteronuclear Diatomic Catalyst
[0043] Step 1: Place urea in an alumina crucible and calcine it in a muffle furnace at 550°C for 4 hours with a heating rate of 5°C / min to obtain a light yellow powder g-C3N4.
[0044] Step 2: Add 150 μL of 0.1 M H₂PtCl₆·6H₂O aqueous solution to 120 mL of water and stir continuously to obtain a homogeneous solution. Then, add 500 mg g-C₃N₄ to the above solution, stir continuously for 24 h, heat at 80 °C to remove the aqueous solvent, and dry at 60 °C overnight. The resulting product is calcined in N₂ at 200 °C for 2 h at a heating rate of 5 °C / min to obtain Pt₁ / g-C₃N₄.
[0045] Step 3: Disperse 300 mg Pt1 / g-C3N4 SACs in 25 mL of water, then add 85 μL of 0.1 M 1,6-hexanediamine aqueous solution. After stirring for 1 h, add 25 μL of 0.1 M HAuCl4·4H2O aqueous solution to the mixture, and stir for another 23 h. After the water has completely evaporated at 80 °C and dried overnight at 60 °C, calcine the collected product at 200 °C for 1 h under N2 at a heating rate of 5 °C / min. The final product is designated as Pt-Au heteronuclear diatomic catalyst.
[0046] Test Example 1
[0047] The supported Pt-Au heteronuclear diatomic catalyst prepared in Example 1 of this application was subjected to microstructural observation, compositional analysis, and performance testing. All electrochemical measurements in the performance testing were performed in an H-type electrolytic cell, using the Pt-Au heteronuclear diatomic catalyst (1.5 × 1.5 cm⁻¹) prepared in Example 1. 2 Using a CHI 760E electrochemical workstation as the working electrode, commercial carbon rods and Hg / HgO were used as the counter and reference electrodes, respectively. A Nafion 211 membrane separated the two chambers of the H-type cell, and the ammonia concentration of the product was determined by UV-Vis spectrophotometry. Utilizing the above H-type electrolytic cell, the supported Pt-Au heteronuclear diatomic catalyst prepared in Example 1 was used to test the electrocatalytic reduction of nitrate to ammonia. The specific steps were as follows: In the cathode electrolyte (containing 7.14 mM NO3...)... - Add 0.1M 60mL KNO3 to the solution, and add 10mL of high-purity argon gas (min) -1 ) The electrolyte was continuously injected into the cathode cell and stirred at 200 rpm. During the reaction, NO3 was subjected to different potentials. - RR conducted a 3-hour experiment, using linear sweep voltammetry (LSV) at 5 mV s. -1 The reaction was carried out at a rate of [missing information] to evaluate the ammonia yield and Faraday efficiency of the catalyst. For stability testing, NO3 [missing information] - The RR experiment was conducted at -0.2V / RHE with a stirring speed of 200 rpm. The electrolyte solution was changed every 3 hours, and the experiment was repeated 5 times under the same working electrode.
[0048] Results analysis:
[0049] (1) The supported Pt-Au heteronuclear diatomic catalyst prepared in Example 1 of this application was observed and photographed using a spherical aberration-corrected high-angle annular dark-field scanning transmission microscope, thereby obtaining the following results: Figure 1 The electron microscope image shown. (By...) Figure 1It can be clearly seen that in the entire region of the Pt1-Au1 / g-C3N4 diatomic catalyst, a large number of atoms are arranged in regular pairs, and only a very small number of atoms are randomly dispersed as single atoms, with no particulate matter present.
[0050] (2) X-ray diffraction was used to analyze the composition of g-C3N4 and the prepared supported Pt-Au heteronuclear diatomic catalyst in Example 1 of this application, thereby obtaining the following results: Figure 2 The X-ray diffraction pattern shown is from... Figure 2 It can be seen that the XRD pattern of the Pt-Au heteronuclear diatomic catalyst is very similar to that of g-C3N4. The absorption peaks at 12.9° and 27.6° correspond to the (002) and (100) crystal planes of g-C3N4, respectively. There are no characteristic peaks of Pt and Au particles, which confirms that Pt and Au species are supported on the g-C3N4 substrate in atomic form.
[0051] (3) Synchrotron radiation was used to analyze the composition of the supported Pt-Au heteronuclear diatomic catalyst prepared in Example 1 of this application, as well as PtO2, Pt foil, Au2O3, and Au foil, to obtain the following results: Figure 3 The image shows a near-edge X-ray absorption fine structure spectrum. Among them, Figure 3 a represents the normalized near-edge X-ray absorption spectrum of the supported Pt-Au heteronuclear diatomic catalyst in Example 1 of this application. It can be seen that the white line intensity of Pt1-Au1 / g-C3N4 is higher than that of the platinum foil but lower than that of PtO2, indicating that Pt carries a partial positive charge (Pt...). δ+ ,0<δ<4). Figure 3 b is the normalized Au L3 edge X-ray absorption near-edge structure spectrum of the supported Pt-Au heteronuclear diatomic catalyst in Example 1 of this application. It can be seen that the white line intensity of the supported Pt-Au heteronuclear diatomic catalyst is between that of Au foil and Au2O3 standard, indicating the presence of cation Au(Au) δ+ ,0<δ<3). From Figure 3 It can be seen that the 1,6-hexanediamine molecule successfully fixes the Pt and Au atoms on the g-C3N4 substrate through Pt-N and Au-N bonds.
[0052] (4) Figure 4 This is a schematic diagram showing the ammonia yield and Faraday efficiency at different potentials in the electrocatalytic reduction of nitrate to ammonia performance test of the supported Pt-Au heteronuclear diatomic catalyst prepared in Example 1.
[0053] (5) Figure 5 This is a schematic diagram illustrating the cyclic performance of the supported Pt-Au heteronuclear diatomic catalyst prepared in Example 1 for the electrocatalytic reduction of nitrate to ammonia. Figure 5It can be seen that the supported Pt-Au heteronuclear diatomic catalyst still has good ammonia yield and Faraday efficiency after 6 cycles.
[0054] The above description is merely a few embodiments of this application and is not intended to limit this application in any way. Although this application discloses preferred embodiments as described above, it is not intended to limit this application. Any changes or modifications made by those skilled in the art without departing from the scope of the technical solution of this application using the disclosed technical content are equivalent to equivalent implementation cases and fall within the scope of the technical solution.
Claims
1. A method for preparing a supported Pt-Au heteronuclear diatomic catalyst, characterized in that, Includes the following steps: S1. Calcining urea yields g-C3N4 powder; S2. Add water and the g-C3N4 powder to the aqueous solution of H2PtCl6 to obtain mixture I. Stir the mixture I, remove the solvent, dry the product and then calcine it II to obtain Pt1 / g-C3N4. S3. Add 1,6-hexanediamine aqueous solution to the aqueous dispersion containing Pt1 / g-C3N4, stir II, then add HAuCl4 aqueous solution to obtain mixture II, stir mixture II III, remove solvent, dry the product and calcine III to obtain the supported Pt-Au heteronuclear diatomic catalyst; The addition of 1,6-hexanediamine serves as a diatomic structure directing agent and stabilizer.
2. The preparation method according to claim 1, characterized in that, In step S1, the conditions for calcination I include: a heating rate of 4℃ / min to 6℃ / min, a calcination temperature of 400℃ to 600℃, and a calcination time of 3h to 5h.
3. The preparation method according to claim 1, characterized in that, In step S2, the concentration of the aqueous solution of H2PtCl6 is 0.05M to 0.25M; Preferably, in step S2, the ratio of the amount of g-C3N4 powder to the aqueous solution of H2PtCl6 and water is 0.5g: 100μL~200μL: 100mL~150mL.
4. The preparation method according to claim 1, characterized in that, In step S2, the conditions for calcination II include: a heating rate of 4℃ / min to 6℃ / min, a calcination temperature of 200℃ to 400℃, and a calcination time of 1h to 3h. Preferably, in step S2, the stirring time is 12h to 36h.
5. The preparation method according to claim 1, characterized in that, In step S3, the concentration of the 1,6-hexanediamine aqueous solution is 0.05M to 0.25M; Preferably, in step S3, the volume ratio of the aqueous dispersion of Pt1 / g-C3N4 to the aqueous solution of 1,6-hexanediamine is 25 mL: 50 μL to 100 μL.
6. The preparation method according to claim 1, characterized in that, In step S3, the concentration of the HAuCl4 aqueous solution is 0.05M to 0.25M; Preferably, in step S3, the volume ratio of the aqueous dispersion of Pt1 / g-C3N4 to the aqueous solution of HAuCl4 is 25 mL: 10 μL to 50 μL.
7. The preparation method according to claim 1, characterized in that, In steps S2 and S3, the conditions for removing the solvent independently include: heating at 60°C to 80°C until the solvent is completely evaporated; Preferably, in steps S2 and S3, the drying conditions independently include: a drying temperature of 60°C to 80°C and a drying time of 6h to 18h.
8. The preparation method according to claim 1, characterized in that, In step S3, the conditions for calcination III include: under an inactive atmosphere, a heating rate of 4℃ / min to 6℃ / min, a calcination temperature of 100℃ to 300℃, and a calcination time of 0.5h to 2h. Preferably, in step S3, the stirring time for step II is 0.5 h to 2 h; Preferably, in step S3, the stirring time for stirring II is 12h to 36h.
9. The supported Pt-Au heteronuclear diatomic catalyst prepared by the preparation method according to any one of claims 1 to 8, characterized in that, Platinum and gold atoms are arranged in pairs on a supported Pt-Au heteronuclear diatomic catalyst.
10. The application of the supported Pt-Au heteronuclear diatomic catalyst prepared by any one of claims 1 to 8 or the supported Pt-Au heteronuclear diatomic catalyst of claim 9 in the reduction of nitrate to ammonia.