Electrocatalyst based on helical carrier modified Cu single atom and preparation method and application thereof
By preparing Cu single-atom catalysts modified with helical supports, the problems of low catalytic activity and poor product selectivity of Cu-based single-atom catalysts were solved, and efficient CO2 reduction to formic acid was achieved, with good stability and high product selectivity.
Patent Information
- Application Number
- CN202411665818.5
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- Filing Date
- 2024-11-20
- Publication Date
- 2026-01-06
- Estimated Expiration
- 2044-11-20
AI Technical Summary
Existing Cu-based single-atom catalysts exhibit low catalytic activity and poor product selectivity in the electrocatalytic reduction of CO2 to formic acid, and the lack of effective support construction methods leads to insufficient regulation of their catalytic activity.
Electrocatalysts with helical supports modified with Cu single atoms were prepared by mixing D-glutamic acid or L-glutamic acid with an aqueous dispersion of pyrrole and reacting with ammonium persulfate to prepare a helical polypyrrole support. This support was then combined with copper acetate tetrahydrate to adjust the Cu single atom content, thus forming a Cu SAs/HCNT catalyst with a helical structure.
It significantly improved the formic acid yield and product selectivity of the catalyst, the Cu single-atom loading was adjustable, the electronic structure was improved, and the activity and stability of the ECO2RR reaction were enhanced.
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Figure CN119663336B_ABST
Abstract
Description
Technical Field
[0001] This invention belongs to the field of single-atom catalytic material preparation technology, specifically relating to an electrocatalyst based on helical support modified Cu single atoms, its preparation method, and its application. Background Technology
[0002] Electrocatalytic CO2 reduction reaction (ECO2RR) technology is considered a key solution to the current greenhouse effect and energy shortage problems. Researchers are dedicated to developing related catalysts to facilitate ECO2RR research, converting CO2 into high-energy-density and high-economic-value carbon-based chemicals or fuels. However, current ECO2RR catalysts still suffer from problems such as low catalytic activity, low product selectivity, and insufficient long-cycle performance.
[0003] Electrocatalysts play a crucial role in the ECO2RR reaction. A good catalyst needs to rapidly enrich reactants, suppress the competing hydrogen evolution reaction (HER), improve product selectivity, and simultaneously address operating conditions including reactivity and stability. Currently, noble metals, non-metallic materials, and metal-organic frameworks are widely used in the ECO2RR reaction. However, due to the uncertainty of active sites in the study of catalysts at general scales such as micrometers and sub-nanometers, the research on these catalysts struggles to reflect the true proton-coupled electron transfer mechanism in the ECO2RR process, and it is also difficult to balance the advantages of both catalytic performance and cost. Single-atom-based catalysts have shown excellent performance in ECO2RR research due to their unique electronic structure, theoretically highest atom utilization efficiency, and stable catalytic performance, and have great potential for industrial application. However, the lack of effective support construction methods for metal Cu single-atom-based catalysts has resulted in insufficient regulation of their catalytic activity, leading to low Faraday selectivity for the electrocatalytic reduction of CO2 to formic acid.
[0004] Therefore, further research is needed on the design and preparation of functional carriers for single-atom active sites of metallic Cu in order to regulate their electronic structure and improve the adsorption relationship between the active center and the formic acid precursor intermediate. The problems of low activity and poor product selectivity of existing Cu-based single-atom catalysts in the electrocatalytic production of formic acid from CO2 also need to be solved. Summary of the Invention
[0005] This invention is based on the above background technology and aims to provide an electrocatalyst based on helical support modified Cu single atoms, its preparation method and application.
[0006] This invention provides a method for preparing an electrocatalyst based on a helical support modified with Cu single atoms, characterized by the following steps: S10, mixing an ethanol dispersion of either D-glutamic acid or L-glutamic acid with an aqueous dispersion of pyrrole to obtain a mixed solution; S20, adding ammonium persulfate to the mixed solution and stirring to react, then separating to obtain helical polypyrrole; S30, dispersing the helical polypyrrole in methanol, adding copper acetate tetrahydrate to it, sonicating and heating to react, separating and drying to obtain a catalyst precursor; S40, annealing, acid washing, washing and drying the catalyst precursor to obtain Cu SAs / HCNT, i.e., an electrocatalyst based on a helical support modified with Cu single atoms, wherein the Cu single atom content in the electrocatalyst based on the helical support modified with Cu single atoms is adjusted by adjusting the amount of copper acetate tetrahydrate added in step S30.
[0007] In the preparation method of an electrocatalyst based on a helical support modified Cu single atom provided by the present invention, it may also have the following features: wherein step S10 includes the following sub-steps: S11, dispersing pyrrole monomer in water and mixing to obtain a first dispersion; S12, ultrasonically dispersing either D-glutamic acid or L-glutamic acid in ethanol to obtain a second dispersion; S13, under low temperature stirring conditions, adding the second dispersion to the first dispersion and stirring for a certain time to obtain a mixed solution.
[0008] In the preparation method of the electrocatalyst based on helical support modified Cu single atom provided by the present invention, it may also have the following features: in step S11, the volume concentration of pyrrole in the first dispersion is 0.2%~0.5%, and the mixing condition is stirring at an ice-water bath for more than 10 min; in step S12, the concentration of D-glutamic acid or L-glutamic acid in the second dispersion is 1.2 mg / mL~2.4 mg / mL, and the mixing condition is stirring at room temperature for more than 15 min; in step S13, the volume ratio of the first dispersion to the second dispersion is 2:1.
[0009] In the preparation method of an electrocatalyst based on a helical support modified with Cu single atoms provided by the present invention, it may also have the following features: wherein step S20 includes the following sub-steps: S21, adding ammonium persulfate to the mixture and stirring to react to obtain a helical polypyrrole dispersion; S22, centrifuging, washing, vacuum drying and grinding the helical polypyrrole dispersion to obtain helical polypyrrole.
[0010] In the preparation method of the electrocatalyst based on helical support modified Cu single atom provided by the present invention, it may also have the following characteristics: wherein the molar ratio of pyrrole in step S10, D-glutamic acid or L-glutamic acid in step S10, and ammonium persulfate in step S21 is 1:1:(1~2), the stirring time is 15 min, and the stirring rate is 800 rpm~2000 rpm.
[0011] In the preparation method of the electrocatalyst based on the modification of Cu single atoms by a helical support provided by the present invention, it may also have the following features: wherein, in step S30, the mass ratio of helical polypyrrole to copper acetate tetrahydrate is 40:(9~36), the ultrasonic time is 30 min~60 min, the heating reaction is carried out by stirring in a water bath at 40 ℃~60 ℃ for 20 h~24 h, the separation method is centrifugation, and the drying method is freeze drying.
[0012] In the preparation method of the electrocatalyst based on helical support modified Cu single atoms provided by the present invention, it may also have the following features: in step S40, the annealing treatment is carried out by heating to 800 ℃~850 ℃ for 2 h~3 h in a tube furnace under an inert atmosphere at a heating rate of 2 ℃ / min~5 ℃ / min; the acid washing method is to disperse in sulfuric acid (aq) for acid washing, the washing liquid is deionized water, and the drying method is freeze drying.
[0013] In the preparation method of the electrocatalyst based on helical support modified Cu single atoms provided by the present invention, it may also have the following feature: wherein the concentration of sulfuric acid (aq) is 1.0 mol / L to 1.2 mol / L.
[0014] The present invention also provides an electrocatalyst based on a helical support modified with Cu single atoms, characterized in that it is prepared by any of the preceding methods for preparing an electrocatalyst based on a helical support modified with Cu single atoms, wherein the electrocatalyst based on the helical support modified with Cu single atoms is a nanofiber with a helical structure, having a diameter of 70 nm to 100 nm and a length of 1 μm to 2 μm, and the Cu single atom loading of the electrocatalyst based on the helical support modified with Cu single atoms is 1.12 wt% to 3.79 wt%.
[0015] This invention also provides an application of an electrocatalyst based on a helical support-modified Cu single atom in the electrocatalytic production of formic acid from CO2. In step S30, when the mass ratio of helical polypyrrole to copper acetate tetrahydrate is 40:18, the electrocatalyst based on the helical support-modified Cu single atom maintains a formic acid product selectivity greater than 80% (-1.05 V, E vs. RHE) and operates stably for more than 30 h.
[0016] The role and effect of invention
[0017] This invention utilizes chiral small molecules as the basic structure to successfully achieve morphological isomerization of the composite catalyst support precursor, giving the composite catalyst typical helical characteristics and the structural potential to regulate the electrochemical microenvironment in the ECO2RR reaction.
[0018] This invention utilizes the universal strategy of electrostatic adsorption to successfully combine metal salts with organic-based carrier precursors, and achieves the regulation and optimization of Cu single-atom loading in Cu SAs / HCNTs. The related preparation techniques are simple and universal, facilitating industrial production practices.
[0019] This invention, by customizing a helical support for Cu single atoms, alters the electronic structure of Cu active sites compared to non-helical supports. This induces the electrons at Cu atomic sites to transition from low-spin to high-spin states, significantly reducing the adsorption free energy of the catalyst Cu SAs / HCNT for key intermediates, improving its ECO2RR reactivity, and increasing the formic acid yield. Attached Figure Description
[0020] Figure 1 This is a flowchart illustrating the preparation method of an electrocatalyst based on a helical support modified with Cu single atoms, as described in an embodiment of the present invention.
[0021] Figure 2 This is a diagram illustrating the preparation strategy of helical polypyrrole in an embodiment of the present invention.
[0022] Figure 3 This is a comparison of SEM images of the helical polypyrrole obtained in catalyst preparation process S22 in the embodiments of the present invention and the non-helical polypyrrole fiber carrier obtained in the preparation process S22 of the control sample.
[0023] Figure 4 This is a comparison of SEM images of catalyst 2 (an electrocatalyst based on a helical support modified with Cu single atoms) and a control sample (an electrocatalyst based on a non-helical support modified with Cu single atoms) in the embodiments of the present invention.
[0024] Figure 5 This is a comparison of TEM images of catalyst 2 and the control sample in an embodiment of the present invention.
[0025] Figure 6 These are TEM images of catalyst 1 and catalyst 3 in embodiments of the present invention.
[0026] Figure 7 This is an AC-TEM image of catalyst 2 in an embodiment of the present invention.
[0027] Figure 8The X-ray photoelectron spectrum of catalyst 2 in the embodiments of the present invention includes N 1s high-resolution and O 1s high-resolution spectra.
[0028] Figure 9 The linear sweep voltammograms (LSVs) of catalysts 1, 2, and 3 in the test examples of this invention are shown. The electrochemical operating conditions are 0.1 M KHCO3 electrolyte in a stationary cell, the scan window is 0 V to -1.65 V (E vs. RHE), and the scan rate is 50 mV / s.
[0029] Figure 10 This is a Faraday efficiency diagram of the ECO2RR reaction products of catalysts 1, 2 and 3 in the test example of the present invention.
[0030] Figure 11 This is a test of the long-cycle stability of catalyst 2 in the test examples of the present invention. Detailed Implementation
[0031] To make the technical means, creative features, objectives and effects of this invention easier to understand, the following embodiments, in conjunction with the accompanying drawings, specifically illustrate an electrocatalyst based on helical support-modified Cu single atoms, its preparation method and application.
[0032] <Example>
[0033] Figure 1 This is a flowchart illustrating the preparation method of an electrocatalyst based on a helical support modified with Cu single atoms, as described in an embodiment of the present invention. Figure 2 This is a diagram illustrating the preparation strategy of helical polypyrrole in an embodiment of the present invention.
[0034] like Figure 1 and 2 As shown, this embodiment provides a method for preparing an electrocatalyst based on a helical support modified with Cu single atoms, including the following steps:
[0035] S10, the mixture is prepared by mixing an ethanol dispersion of either D-glutamic acid or L-glutamic acid with an aqueous dispersion of pyrrole, specifically including the following sub-steps:
[0036] S11, 0.498 mL of pyrrole monomer was dispersed in 120 mL of deionized water and stirred in an ice-water bath for more than 10 min to obtain the first dispersion;
[0037] S12, 1.05 g of either D-glutamic acid or L-glutamic acid is ultrasonically dispersed in 60 mL of ethanol and stirred at room temperature for more than 15 min to obtain a second dispersion.
[0038] S13, under ice-water bath and magnetic stirring at 1000 rpm, the second dispersion was added to the first dispersion in one go and stirred for 15 min to obtain a mixture.
[0039] S20, ammonium persulfate is added to the mixture and stirred to react, and the spiral polypyrrole is separated. The specific steps include the following:
[0040] S21, 1.8 g of ammonium persulfate was added to the mixture and the mixture was stirred for 1.5 h to obtain a spiral polypyrrole dispersion;
[0041] S22, the spiral polypyrrole dispersion was centrifuged, washed (to remove excess reactants and small by-product molecules), vacuum dried and ground to obtain black spiral polypyrrole.
[0042] S30: Weigh 200 mg of spiral polypyrrole and disperse it in methanol. Add 45 mg to 180 mg of copper acetate tetrahydrate, sonicate for 30 min, stir in a water bath at 40 °C for 24 h, centrifuge and freeze dry to obtain the catalyst precursor.
[0043] S40, the catalyst precursor was heated to 800℃ for 2 h in a tube furnace under an argon atmosphere at a heating rate of 5 ℃ / min, then dispersed in 1 M sulfuric acid solution for acid washing, followed by washing with deionized water, and finally dried to obtain Cu SAs / HCNT, which is an electrocatalyst based on Cu single atoms modified by a helical support.
[0044] This embodiment also provides an electrocatalyst based on helical support-modified Cu single atoms, which is prepared by the preparation method of the electrocatalyst based on helical support-modified Cu single atoms in this embodiment.
[0045] In this embodiment, three electrocatalysts based on helical support-modified Cu single atoms (Cu SAs / HCNT) were prepared and designated as catalyst 1, catalyst 2 and catalyst 3, respectively.
[0046] The preparation processes of catalysts 1, 2, and 3 are largely similar, with the only difference being the amount of copper acetate tetrahydrate added in step S30 of the preparation process: 45 mg, 90 mg, and 180 mg, respectively. The Cu loadings in the three catalysts are 1.12 wt%, 2.01 wt%, and 3.79 wt%, respectively.
[0047] In this embodiment, a non-helical Cu single-atom electrocatalyst (Cu SAs / NHCNT) was also prepared, designated as the control sample. The preparation process and parameters of the control sample were largely similar to those of catalyst 1, with the only difference being that the raw material used in step S12 of the preparation process was a racemic mixture of glutamic acid (DL-glutamic acid).
[0048] Figure 3 This is a comparison of SEM images of the helical polypyrrole obtained in catalyst preparation process S22 in the embodiments of the present invention and the non-helical polypyrrole fiber carrier obtained in the preparation process S22 of the control sample.
[0049] like Figure 3 As shown, the helical polypyrrole carrier exhibits obvious helical twisting characteristics and a relatively rough surface. In contrast, although non-helical polypyrrole is similar to helical polypyrrole in fiber length and diameter, it does not show any twisting characteristics and has a relatively smooth surface.
[0050] Figure 4 This is a comparison of SEM images of catalyst 2 (an electrocatalyst based on a helical support modified with Cu single atoms) and a control sample (an electrocatalyst based on a non-helical support modified with Cu single atoms) in the embodiments of the present invention. Figure 5 This is a comparison of TEM images of catalyst 2 and the control sample in an embodiment of the present invention.
[0051] like Figure 4 and 5 As shown, catalyst 2 is a nanofiber with a helical structure, with a diameter of 70 nm to 100 nm and a length of 1 μm to 2 μm, consistent with the precursor support. Catalyst 2 exhibits obvious helical twisting characteristics, and the carbonized support structure shows a clear pitch. In contrast, the control sample is consistent with its precursor template, non-helical polypyrrole fibers, and no pitch or twisting characteristics were observed; its surface is relatively smooth.
[0052] Figure 6 These are TEM images of catalyst 1 and catalyst 3 in embodiments of the present invention.
[0053] like Figure 6 As shown, the helical polypyrrole template exhibits good compatibility with Cu single atoms. The morphology of the composite catalyst under different loadings does not show significant changes. Even in catalyst 3 with the highest Cu loading, no Cu metal-related particles or Cu species aggregations were observed. This indicates that Cu single atoms are well dispersed on the helical support according to the above strategy.
[0054] Figure 7 This is an AC-TEM image of catalyst 2 in an embodiment of the present invention.
[0055] like Figure 7 As shown, the Cu species atomic images of catalyst 2 (an electrocatalyst based on a helical support-modified Cu single atom) in this embodiment are clearly distinguishable.
[0056] Figure 8 The X-ray photoelectron spectrum of catalyst 2 in the embodiments of the present invention includes N 1s high-resolution and O 1s high-resolution spectra.
[0057] like Figure 8 As shown, the chemical structure of catalyst 2 was analyzed using X-ray photoelectron spectroscopy. From the presence of Cu-N peaks in the N 1s high-resolution spectrum and Cu-O peaks in the O 1s high-resolution spectrum, it can be seen that Cu single atoms in the catalyst are co-coordinated with N and O.
[0058] <Test Example>
[0059] This test example demonstrates the electrochemical performance of catalysts 1, 2, and 3 in the examples and provides an application of an electrocatalyst based on a helical support-modified Cu single atom in the electrocatalytic production of formic acid from CO2.
[0060] First, the electrochemical performance of catalysts 1, 2, and 3 was tested in a fixed cell.
[0061] Figure 9 The linear sweep voltammograms (LSVs) of catalysts 1, 2, and 3 in the test examples of this invention are shown. The electrochemical operating conditions are 0.1 M KHCO3 electrolyte in a fixed cell, the scan window is 0 V to -1.65 V (E vs. RHE), and the scan rate is 50 mV / s. Figure 10 This is a Faraday efficiency diagram of the ECO2RR reaction products of catalysts 1, 2 and 3 in the test example of the present invention.
[0062] like Figure 9 and 10 As shown, catalyst 2 (with a Cu loading of 2.01 wt%) exhibits the highest Faraday efficiency in the electrocatalytic reduction of CO2 to formic acid at -1.05 V (E vs. RHE).
[0063] Figure 11 This is a test of the long-cycle stability of catalyst 2 in the test examples of the present invention.
[0064] like Figure 11 As shown, catalyst 2, as the optimal sample, can maintain a high level of formic acid product selectivity greater than 80% (-1.05 V, E vs. RHE) under high current and operate stably for more than 30 h.
[0065] Those skilled in the art should understand that this invention is not limited to the above embodiments. The embodiments and descriptions in the specification are merely illustrative of the principles of the invention. Various changes and modifications can be made to this invention without departing from its spirit and scope, and all such changes and modifications fall within the scope of the invention as claimed. The scope of protection of this invention is defined by the appended claims and their equivalents.
Claims
1. A method for preparing an electrocatalyst based on Cu single atoms modified by a helical support, characterized in that, The method comprises the following steps: S10, mixing an ethanol dispersion of one of D-glutamic acid or L-glutamic acid and an aqueous dispersion of pyrrole to obtain a mixture; S20, adding ammonium persulfate to the mixture and stirring to react to obtain a helical poly-pyrrole; S30, dispersing the helical poly-pyrrole in methanol, adding copper acetate tetrahydrate to the helical poly-pyrrole, ultrasonicating, and then heating to react, and then separating and drying to obtain a catalyst precursor, the mass ratio of the helical poly-pyrrole to the copper acetate tetrahydrate being 40:(9-36); S40, annealing, pickling, washing, and drying the catalyst precursor to obtain Cu SAs / HCNT, i.e., an electrocatalyst based on a helical carrier modified Cu monatomic, wherein the content of Cu monatomic in the electrocatalyst based on a helical carrier modified Cu monatomic is adjusted by adjusting the amount of the copper acetate tetrahydrate in step S30.
2. The method according to claim 1, wherein: wherein step S10 comprises the following sub-steps: S11, dispersing pyrrole monomers in water to obtain a first dispersion; S12, ultrasonicating one of D-glutamic acid or L-glutamic acid in ethanol to obtain a second dispersion; S13, under low-temperature stirring conditions, adding the second dispersion to the first dispersion and stirring for a certain period of time to obtain the mixture.
3. The method according to claim 2, wherein: wherein in step S11, the volume concentration of pyrrole in the first dispersion is 0.2%-0.5%, and the mixing condition is stirring for more than 10 min in an ice water bath, in step S12, the concentration of D-glutamic acid or L-glutamic acid in the second dispersion is 1.2 mg / mL-2.4 mg / mL, and the mixing condition is stirring for more than 15 min at room temperature, in step S13, the volume ratio of the first dispersion to the second dispersion is 2:
1.
4. The method according to claim 1, wherein: wherein step S20 comprises the following sub-steps: S21, adding ammonium persulfate to the mixture and stirring to react to obtain a helical poly-pyrrole dispersion; S22, centrifuging, washing, vacuum drying, and grinding the helical poly-pyrrole dispersion to obtain the helical poly-pyrrole.
5. The method according to claim 4, wherein: wherein the molar ratio of pyrrole in step S10, D-glutamic acid or L-glutamic acid in step S10, and ammonium persulfate in step S21 is 1:1:(1-2), the stirring time is 15 min, and the stirring rate is 800 rpm-2000 rpm.
6. The method according to claim 1, wherein: wherein in step S30, the ultrasonicating time is 30 min-60 min, The heating reaction is stirred at 40-60 °C for 20-24 h, The separation is centrifugation, The drying is freeze-drying.
7. The method of claim 1, wherein the annealing is performed in a tube furnace under inert atmosphere at a heating rate of 2-5 °C / min to 800-850 °C for 2-3 h. wherein The acid pickling is performed by dispersing in a sulfuric acid solution. The washing liquid is deionized water. The drying is freeze-drying.
8. The method of claim 7, wherein the concentration of the sulfuric acid solution is 1.0-1.2 mol / L. The method of any one of claims 1-8, wherein The Cu single atom-based electrocatalyst is a nanofiber with a helical structure, having a diameter of 70-100 nm and a length of 1-2 μm.
9. An electrocatalyst based on helical support modified Cu single atoms, characterized in that, The Cu single atom-based electrocatalyst has a Cu single atom loading of 1.12-3.79 wt%.
10. The Cu single atom-based electrocatalyst of claim 9 for use in electrocatalytic CO2 reduction to formic acid. When the mass ratio of the helical polypyrrole to copper acetate tetrahydrate in step S30 is 40:18, the Cu single atom-based electrocatalyst can maintain a formic acid product selectivity of greater than 80% at a potential of -1.05 V vs. RHE and can be stably operated for greater than 30 h. wherein
Citation Information
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