A method for preparing and applying a cobalt-deficient cobalt selenide-anchored high-loading Pt single-atom catalyst
By constructing Co defect sites on the surface of cobalt selenide to anchor Pt single atoms, the problems of thermodynamic instability and low loading of single-atom catalysts in acidic media were solved, achieving efficient preparation of H2O2.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- BEIJING HYDRO ENERGY TECH CO LTD
- Filing Date
- 2024-05-10
- Publication Date
- 2026-05-26
AI Technical Summary
Existing single-atom catalysts exhibit thermodynamic instability during synthesis and catalytic reactions, are prone to aggregation, and have low loading, resulting in insufficient catalytic activity and selectivity, making it difficult to efficiently prepare H2O2 in acidic media.
A defect engineering strategy was adopted to prepare well-ordered cobalt selenide via a one-step hydrothermal method, and potassium thiocyanate was directionally adsorbed on its surface. After ultrasonic exfoliation and calcination, Co defective cobalt selenide was formed, which was used to anchor high-load Pt single atoms to improve its stability and catalytic activity.
Stable dispersion of high-load Pt single atoms was achieved, which significantly improved the selectivity and yield of H2O2 in acidic media and enhanced the electrocatalytic oxygen reduction performance.
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Figure CN118287112B_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of electrochemical technology, specifically to a method for preparing and applying a cobalt-deficient cobalt selenide-anchored high-loading Pt single-atom catalyst. Background Technology
[0002] H2O2 is an important industrial chemical widely used in medical disinfection, paper bleaching, wastewater treatment, and fine chemical synthesis. Currently, the synthesis of H2O2 mainly relies on the anthraquinone process, which involves multiple complex processes, requires significant infrastructure investment, and is environmentally polluting. Through electrochemical processes (2e... - ORR (Organic Reactive Oxygen Regulator) synthesis of H2O2 is an alternative green route because it utilizes only O2 and H2O as raw materials. However, due to the four-electron (4e)... - Competition for the ORR reaction pathway makes 2e - The ORR process exhibits low selectivity. In recent years, the electrocatalytic ORR production of H2O2 in acidic media has attracted widespread attention. Compared to alkaline electrolytes, acidic electrolytes can effectively suppress the self-decomposition of H2O2 and have good compatibility with commercial proton exchange membrane electrolysis devices, significantly reducing production costs. To realize the application of this technology, the development of highly active and selective electrocatalysts is crucial.
[0003] Many catalysts for the preparation of H2O2 using acidic ORR have been developed, including metal alloys, transition metal compounds, single-atom catalysts (SACs), and carbon materials. Among them, SACs have been extensively studied due to their highest atom utilization, tunable electronic structure, and excellent catalytic performance. The strong interaction between individual metal atoms and the support ensures the stable dispersion of metal atoms on the support surface without aggregation. SACs with monodisperse active sites can promote the adsorption of *O2 in the form of "terminal oxygen," thereby reducing the breaking of OO bonds and effectively improving the selectivity of H2O2. However, single-atom catalysts exhibit thermodynamic instability due to their high surface energy. During synthesis and catalytic reactions, they are often accompanied by the aggregation and migration of single-atom sites, forming nanoclusters or nanoparticles, thus losing the advantages of single atoms. At the same time, the high surface energy of single atoms tends to result in low loading and limited mass activity. To address this problem, in recent years, scholars at home and abroad have developed various methods for synthesizing single-atom catalysts, including "defect engineering strategies," "spatial confinement strategies," and "ligand coordination strategies." Among them, the "defect engineering strategy" of anchoring single atoms by constructing defect sites on the surface of transition metal compound supports is a simple and effective synthesis method. The strong charge transfer effect between single atoms and the defective support surface can effectively prevent the transfer and aggregation of single atoms during synthesis and catalytic reaction, achieving a high loading capacity and good stability of single atoms.
[0004] In metal selenides, represented by cobalt selenide, the low electronegativity of Se weakens the attraction of outer electrons to Co, generating more weakly bound electrons and thus contributing to an increased redox reaction rate. Meanwhile, cobalt selenide possesses advantages such as a narrow band gap, acid resistance, simple preparation, chemical stability, and low cost, leading to its application in the electrocatalytic acidic ORR reaction to H₂O₂. Constructing Co-defective cobalt selenide anchored to Pt single atoms using defect engineering strategies can effectively increase the Pt single-atom loading and stability, thereby enhancing the catalyst's catalytic activity and selectivity for oxygen reduction to H₂O₂. Summary of the Invention
[0005] The purpose of this invention is to provide a method for preparing and applying a cobalt-deficient cobalt selenide-anchored high-loading Pt single-atom catalyst. First, well-structured cobalt selenide is obtained via a one-step hydrothermal method. Then, an appropriate amount of potassium thiocyanate is added to an anhydrous ethanol dispersion of cobalt selenide, and the mixture is thoroughly stirred to achieve SCN. - The directional adsorption of Co sites on the surface is followed by ultrasonic exfoliation, water washing, alcohol washing, and drying in a vacuum drying oven. After calcination in a tube furnace, Co selenide with Co defects is finally obtained. Co-defective cobalt selenide can anchor high-load Pt single atoms, improving the stability of Pt single atoms. When used in the electrocatalytic oxygen reduction reaction to prepare H2O2, it exhibits higher catalytic activity and selectivity compared to Co-defective cobalt selenide.
[0006] One objective of this invention is to provide a method for preparing a cobalt-deficient cobalt selenide-anchored high-loading Pt single-atom catalyst, which specifically includes the following steps:
[0007] (1) Weigh a certain amount of selenium powder and add it to a NaOH solution with a concentration of 0.133 g / mL. Stir vigorously for 30-60 min to obtain mixture A; weigh a certain amount of cobalt nitrate hexahydrate and add it to an EDTA-2Na solution with a concentration of 0.25 mol / L. Stir vigorously for 30-60 min to obtain mixture B;
[0008] (2) Add mixture B to mixture A and stir for 10-30 min to obtain mixture C. Transfer mixture C to a reactor for hydrothermal reaction. The temperature of the hydrothermal reaction is 200 °C and the reaction time is 6 h. After the hydrothermal reaction is completed, the reactor is naturally cooled to room temperature. Then, the product in the reactor is centrifuged and the black precipitate is collected and washed three times with hydrochloric acid solution. Then, it is washed with ultrapure water until the washing liquid is neutral. After that, the precipitate is collected and placed in a vacuum drying oven and dried at 60 °C for 24 h to obtain cobalt selenide powder.
[0009] (3) Weigh a certain amount of cobalt selenide powder prepared in step (2), add it to a beaker containing anhydrous ethanol and disperse it, then add a certain amount of potassium thiocyanate powder to the beaker and stir vigorously for 30-60 min; then transfer the beaker to a cell disruptor and ultrasonically exfoliate at 40-50 ℃ for 2-4 h, with an ultrasonic power of 100-250 W, a centrifuge speed of 7500 rpm, and a centrifugation time of 4-6 min. Centrifuge the dispersion after ultrasonic exfoliation, wash the precipitate with anhydrous ethanol 5 times, collect the precipitate, transfer it to a vacuum drying oven for drying, and place the dried sample in a tube furnace and calcine at 300 ℃ for 2 h in an air atmosphere to obtain cobalt selenide rich in Co defects.
[0010] (4) Weigh a certain amount of the Co-defect-rich cobalt selenide prepared in step (3), disperse it uniformly in an ammonium hydroxide aqueous solution, adjust the pH of the solution to 11~13, then slowly add a certain amount of ammonia solution containing tetraammineplatinum nitrate, stir at room temperature for 24 h, then centrifuge to separate, wash the precipitate with water by centrifugation, and then vacuum dry. The dried powder is calcined at 300 ℃ for 2 h in a H2 / Ar mixed atmosphere to obtain a cobalt defect-type cobalt selenide anchored high-load Pt single-atom catalyst.
[0011] As a preferred embodiment of the present invention, the molar ratio of selenium powder to Co(NO3)2·6H2O is 2:1.
[0012] As a preferred embodiment of the present invention, the mass ratio of cobalt selenide powder to potassium thiocyanate powder added in step (3) is 1:0.04~0.14.
[0013] As a preferred embodiment of the present invention, the heating rate during calcination in steps (3) and (4) is 5 °C / min.
[0014] As a preferred embodiment of the present invention, the concentration of the ammonium hydroxide aqueous solution in step (4) is 0.1 mol / L, and the mass ratio of the added Co-defect-rich cobalt selenide to the volume of the ammonium hydroxide aqueous solution is 1 g: 150 mL.
[0015] As a preferred embodiment of the present invention, in step (4), the concentration of tetraammineplatinum nitrate in the ammonia solution is 0.005-0.15 mol / L, and the volume ratio of its addition to the volume of the ammonium hydroxide solution is 1:3.
[0016] As a preferred embodiment of the present invention, the volume percentages of H2 and Ar in the H2 / Ar mixed atmosphere in step (4) are 5% and 95%, respectively.
[0017] The cobalt-defective cobalt selenide-anchored high-loading Pt single-atom catalyst prepared according to the above method is in the form of nanosheets.
[0018] This invention also provides an application of the prepared cobalt-deficient cobalt selenide-anchored high-loading Pt single-atom catalyst as an electrocatalyst, particularly its application in the electrocatalytic reduction of oxygen to H₂O₂ in acidic media. The cobalt-deficient cobalt selenide-anchored high-loading Pt single-atom catalyst at 0 V... vs The hydrogen peroxide yield under RHE was 225.5 mmol / g. cat. -1 h -1 Therefore, the cobalt-deficient cobalt selenide-anchored high-loading Pt single-atom catalyst further improves the acidity of 2e- - ORR performance.
[0019] Compared with existing technologies, this invention has significant advantages and beneficial effects. Through the above technical solution, this invention achieves considerable technological advancement and practicality, and has broad application value, possessing at least the following advantages:
[0020] (1) This invention uses selenium powder as the selenium source and cobalt salt as the cobalt source to obtain well-structured cobalt selenide through a one-step hydrothermal method. A certain amount of potassium thiocyanate white crystalline powder is added to an anhydrous ethanol solution of cobalt selenide and stirred thoroughly to achieve SCN. - Directed adsorption at Co sites makes CoSCN more soluble in organic solutions, and ultrasonic exfoliation accelerates the dissolution of SCN. - The process of directional adsorption of Co at Co sites and dissolution of CoSCN in organic solvents, followed by ultrasonic exfoliation, washing with water and alcohol, drying in a vacuum drying oven, and then calcination in a tube furnace at a specific temperature, ultimately achieves controllable modulation and uniform distribution of cation defect concentration, yielding Co-defective cobalt selenide. Further, Pt is anchored to the Co defect sites on the surface of the Co-defective cobalt selenide. By controlling the concentration of the ammonia solution in tetraammineplatinum nitrate, the pH of the solution, and factors such as calcination temperature, calcination time, and heating rate during post-treatment, a high-load Pt single-atom catalyst is finally prepared. The prepared Co-defective cobalt selenide-anchored high-load Pt single-atom catalyst can effectively regulate the adsorption configuration of oxygen-containing intermediates and possesses suitable binding energy. When used in the electrocatalytic oxygen reduction reaction to prepare H₂O₂, it exhibits higher activity and selectivity compared to Co-defective cobalt selenide.
[0021] (2) This invention utilizes a Co-defective cobalt selenide-anchored high-loading Pt single-atom catalyst, which possesses high stability, a large specific surface area, and good conductivity. It exhibits good electrocatalytic oxygen reduction to H2O2 production performance in acidic media, demonstrating higher activity, selectivity, and yield. The Co-defective cobalt selenide-anchored high-loading Pt single-atom catalyst sample exhibits a nanosheet morphology at 0.3 V. vs During RHE, the selectivity of H2O2 significantly increased to 97%, which is beneficial for 2e-. -The process of ORR to H2O2. Co-defective cobalt selenide anchors the double-layer capacitance (C) of a highly loaded Pt single-atom catalyst. dl The value is 0.61 mFcm -2 This indicates that it has a high electrochemical active surface area, which is beneficial for 2e - ORR procedure. At 0 V vs Under RHE conditions, the hydrogen peroxide yield of a Co-defective cobalt selenide-anchored high-loading Pt single-atom catalyst was 225.5 mmol g. cat. -1 h -1 Therefore, Co-defective cobalt selenide-anchored high-loading Pt single-atom catalysts significantly improve the acidity of 2e⁻. - ORR performance.
[0022] (3) The preparation method of the present invention is simple and can obtain a cobalt-deficient cobalt selenide anchored high-load Pt single-atom catalyst rapidly and at low cost under mild conditions. The obtained Co-deficient cobalt selenide anchored high-load Pt single-atom catalyst can effectively reduce oxygen to hydrogen peroxide under electrocatalytic conditions, which solves the problems of low activity and poor selectivity of current catalysts for producing hydrogen peroxide under acidic conditions. Attached Figure Description
[0023] Figure 1 These are transmission electron microscopy (a) and aberration electron microscopy (b) images of the cobalt defect cobalt selenide anchored high-loading Pt single-atom catalyst powder prepared in Example 1.
[0024] Figure 2 The X-ray crystal diffraction patterns are those of the cobalt defect cobalt selenide anchored high-load Pt single-atom catalyst (sample II) prepared in Example 1 and the Co defect cobalt selenide (sample I) prepared in steps (1)-(3).
[0025] Figure 3 The Raman spectra of the cobalt-defect cobalt selenide anchored high-load Pt single-atom catalyst prepared in Example 1 (sample II) and the Co-defect cobalt selenide prepared in steps (1)-(3) (sample I) are shown.
[0026] Figure 4 These are XPS images of the cobalt-defect cobalt selenide anchored high-loading Pt single-atom catalyst prepared in Example 1 (sample II) and the Co-defect cobalt selenide prepared in steps (1)-(3) (sample I);
[0027] Figure 5 The polarization curves of the cobalt defect cobalt selenide anchored high-loading Pt single-atom catalyst (sample II) prepared in Example 1 and the Co defect cobalt selenide (sample I) prepared in steps (1)-(3) for electrocatalytic oxygen reduction to hydrogen peroxide are shown.
[0028] Figure 6 This is a catalytic selectivity diagram of the cobalt-deficient cobalt selenide anchored high-loading Pt single-atom catalyst prepared in Example 1 (sample II) and the Co-deficient cobalt selenide prepared in steps (1)-(3) (sample I);
[0029] Figure 7 The electron transfer diagrams are of the cobalt defect cobalt selenide anchored high-loading Pt single-atom catalyst prepared in Example 1 (sample II) and the Co defect cobalt selenide prepared in steps (1)-(3) (sample I).
[0030] Figure 8 The double-layer capacitance diagrams are of the cobalt defect cobalt selenide anchored high-loading Pt single-atom catalyst (sample II) prepared in Example 1 and the Co defect cobalt selenide (sample I) prepared in steps (1)-(3).
[0031] Figure 9 The figures show the yield and Faraday efficiency of the cobalt-deficient cobalt selenide anchored high-load Pt single-atom catalyst (sample II) prepared in Example 1 and the Co-deficient cobalt selenide (sample I) prepared in steps (1)-(3) for catalytic oxygen reduction to H2O2. Detailed Implementation
[0032] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the present invention will be clearly and completely described below in conjunction with specific embodiments and accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of the present invention, not all of them. The embodiments described and shown in the accompanying drawings can generally be implemented through various different configurations. Therefore, the following detailed description of the embodiments of the present invention provided in the accompanying drawings is not intended to limit the scope of the claims, but merely to illustrate selected embodiments of the present invention. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without inventive effort are within the scope of protection of the present invention.
[0033] This invention does not impose any special restrictions on the source of any of the raw materials used; they can be commercially available or self-made, and there are no special restrictions on their purity.
[0034] Example 1:
[0035] (1) Weigh 0.32 g of selenium powder and add it to a beaker containing 30 mL of NaOH (4 g of NaOH, from Guoyao) solution. Stir vigorously for 30 min to obtain mixture A. Weigh 0.587 g of cobalt nitrate hexahydrate and add it to a beaker containing 10 mL of 0.25 M EDTA-2Na solution. Stir vigorously for 30 min to obtain mixture B.
[0036] (2) Add mixture B to mixture A and stir for 20 min to obtain mixture C. Transfer mixture C to a reactor for hydrothermal reaction at a temperature of 200 °C for 6 h. After the hydrothermal reaction is completed, allow the reactor to cool naturally to room temperature. Then, centrifuge the product in the reactor and collect the black precipitate. Disperse the black precipitate in 100 mL of 0.1 mol / L hydrochloric acid solution and stir for 6 h. Then centrifuge. Repeat this process three times with 100 mL of 0.1 mol / L hydrochloric acid solution each time, and centrifuge with ultrapure water until the washing solution is neutral. The centrifuge parameters are 7500 rpm and the centrifugation time is 4 min. After that, collect a large amount of black precipitate and place it in a vacuum drying oven at 60 °C for 24 h to obtain cobalt selenide powder.
[0037] (3) Weigh 1.0 g of the cobalt selenide powder prepared in step (2) and add it to a beaker containing 100 mL of anhydrous ethanol for dispersion. Then add 0.1344 g of potassium thiocyanate white crystalline powder to the beaker and stir vigorously for 60 min. Then transfer the beaker to a cell disruptor and sonicate it at 40~50℃ for 4 h with an ultrasonic power of 100 W. Centrifuge the sonicated cobalt selenide dispersion at 7500 rpm for 4 min. Wash the precipitate with anhydrous ethanol five times. Then collect the black precipitate and transfer it to a vacuum drying oven to dry at 80℃ for 12 h. Place the dried sample in a tube furnace and calcine it at 300℃ (heating rate of 5℃ / min) for 2 h in an air atmosphere to finally obtain cobalt selenide rich in Co defects, which is recorded as sample I.
[0038] (4) Weigh 0.2 g of the cobalt-defect-rich cobalt selenide powder prepared in step (3), and uniformly disperse it in 30 mL of 0.1 mol / L ammonium hydroxide aqueous solution, and adjust the pH of the solution to 12. Then slowly add 10 mL of ammonia solution containing tetraammineplatinum nitrate, the concentration of tetraammineplatinum nitrate in the ammonia solution being 0.01 mol / L, stir at room temperature for 24 h, then centrifuge, wash the precipitate with water four times by centrifugation, and then dry it in a vacuum oven at 80 ℃ for 12 h. Calcine the dried powder at 300 ℃ for 2 h in a mixed atmosphere of H2 / Ar (H2 and Ar volume percentages being 5% and 95%, respectively), with a heating rate of 5 ℃ / min, to obtain a cobalt-defect-type cobalt selenide-anchored high-loading Pt single-atom catalyst (hereinafter referred to as "high-loading Pt single-atom catalyst"), designated as sample ⅠⅠ.
[0039] Figure 1Transmission electron microscopy (TEM) images (a) and aberration-corrected electron microscopy (AEM) images (b) of the high-load Pt single-atom catalyst prepared in Example 1 are shown. The TEM image reveals that the prepared high-load Pt single-atom catalyst exhibits a nanosheet morphology. The AEM image shows that the Pt on the catalyst surface is monodisperse, and the Pt loading was determined to be 1.5% by inductively coupled plasma atomic emission spectrometry (ICP). wt .%.
[0040] Electrochemical performance testing procedure for high-loading Pt single-atom catalyst (sample II):
[0041] 5 mg of high-loading Pt single-atom catalyst and 1 mg of conductive carbon black were weighed, added to 750 μL of isopropanol and 250 μL of ultrapure water, followed by the addition of 10 μL of 5% Nafion solution. The mixture was ultrasonicated until the catalyst was uniformly dispersed, yielding a dispersion. 2.5 μL of this dispersion was drop-coated onto a rotating ring-disk electrode to obtain the working electrode. A carbon rod and a saturated silver chloride electrode were used as the counter and reference electrodes, respectively. Testing was performed using a Chenhua CHI760e electrochemical workstation with a rotating ring-disk instrument. The electrolyte was a 0.1 mol / L HClO4 solution. Before the ORR electrochemical test, Ar gas was passed through the electrolyte for 30 min for CV activation, followed by oxygen passage for 30 min. The polarization curves were obtained at a scanning rate of 10 mV / s at 1600 rpm, with a ring voltage of 1.3 V relative to the standard hydrogen electrode and a disk voltage of -0.35 to 0.55 V relative to the saturated silver chloride electrode. All data were acquired after the scanning current stabilized.
[0042] 200 μL of the dispersion was drop-coated onto a 2.5 cm × 2.5 cm gas diffusion carbon paper to obtain an electrode sheet. Electrocatalytic oxygen reduction to hydrogen peroxide was tested in a flow electrolytic cell using a 0.1 mol / L HClO4 solution. Under oxygen saturation, 0 V was obtained. vs The yield graph of hydrogen peroxide under RHE is shown below. Figure 9 As shown.
[0043] The electrochemical performance of Co-defective cobalt selenide (sample I) prepared in steps (1) to (3) was tested according to the above test method.
[0044] Figure 2The X-ray diffraction patterns of the high-load Pt single-atom catalyst (sample II) prepared in Example 1 and the Co-defect cobalt selenide (sample I) prepared in steps (1)-(3) are compared with the data of the cobalt selenide standard PDF card. Each diffraction peak can be assigned to the peaks of the (110), (011), (101), (111), (120), (121), (211), (002), (031), (131), (310), and (122) crystal planes of the cobalt selenide standard PDF card, which is consistent with the standard data, indicating that the material is cobalt selenide. Since Pt is in a monodisperse state, no diffraction peaks were found.
[0045] Figure 3 These are Raman spectra of the high-loading Pt single-atom catalyst (sample II) prepared in Example 1 and the Co-defective cobalt selenide (sample I) prepared in steps (1)-(3), used to analyze the structural information of the samples. Figure 3 It can be seen that the sample is 168cm. -1 and 668 cm -1 There are two typical characteristic peaks at this point, which are attributed to the A of Se-Se in CoSe2. g and A 1g Vibrational model. Compared with Co-defective cobalt selenide, the characteristic peaks of the high-loading Pt single-atom catalyst show slight changes, which may be due to the introduction of Pt.
[0046] Figure 4 XPS spectra of the high-load Pt single-atom catalyst (sample II) prepared in Example 1 of this invention and the Co-defective cobalt selenide (sample I) prepared in steps (1)-(3). It can be seen that the Co 2p spectra of both the high-load Pt single-atom catalyst and the Co-defective cobalt selenide have four peaks, including Co 2p... 1 / 2 Co 2p 3 / 2 And two satellite peaks. Compared with Co-deficient cobalt selenide, the Co 2p peak of the high-load Pt single-atom catalyst shifts to a lower binding energy direction by 0.48 eV, which means that the incorporation of Pt affects the electronic structure of Co on the surface of Co-deficient cobalt selenide. In addition, the proportion of Co-Se bonds is reduced, which may be due to the formation of more Pt-Se bonds. Figure 4 As shown in (b), the binding energies of 54.78 eV and 55.63 eV correspond to Se in CoSe2, respectively. 2- Se 3d 3 / 2 and Se 3d 5 / 2 The Se 3d peak at 59.4 eV originates from oxidized Se. Compared to Co-deficient cobalt selenide, the Se 3d peak of the highly loaded Pt single-atom catalyst shows a significant shift. This is likely due to electron transfer from Pt to Se.
[0047] Figure 5 The polarization curves of the high-load Pt single-atom catalyst (sample II) prepared in Example 1 of this invention and the Co-defect cobalt selenide (sample I) prepared in steps (1)-(3) for electrocatalytic oxygen reduction to hydrogen peroxide are shown. It can be seen that the ring current of the high-load Pt single-atom catalyst (sample II) is much higher than that of the Co-defect cobalt selenide (sample I). The ring currents of all samples at 0.3 V relative to the standard hydrogen electrode are 0.70 mAcm. -2 (Sample II) and 0.39 mAcm -2 (Sample I).
[0048] Figure 6 The catalytic selectivity diagrams are shown for the high-load Pt single-atom catalyst (sample II) prepared in Example 1 of this invention and the Co-defective cobalt selenide (sample I) prepared in steps (1)-(3). It can be seen that at 0.3 V, the selectivity for H2O2 significantly increases from 63% (sample I) to 97% (sample II). Clearly, the high-load Pt single-atom catalyst is beneficial for 2e- - ORR is the process of converting to H2O2.
[0049] Figure 7 Electron transfer number diagrams are shown for the high-loading Pt single-atom catalyst (sample II) prepared in Example 1 of this invention and the Co-defective cobalt selenide (sample I) prepared in steps (1)-(3). The calculated Co-defective cobalt selenide (sample I) at 0.3 V... vs The electron transfer number at RHE is 2.85, while that of the high-load Pt single-atom catalyst (sample II) at 0.3 V is higher. vs The electron transfer number at RHE is 2.05, which is closer to the theoretical electron transfer number.
[0050] Figure 8 The electric double-layer capacitance diagrams are shown for the high-loading Pt single-atom catalyst (sample II) prepared in Example 1 of this invention and the Co-defective cobalt selenide (sample I) prepared in steps (1)-(3). It can be seen that C... dl They are 0.61 mFcm -2 (Sample II) and 0.32 mFcm -2 (Sample I). Clearly, the high-loading Pt single-atom catalyst possesses a higher electrochemical active surface area, which is beneficial for 2e... - ORR procedure.
[0051] Figure 9The yield and Faradaic efficiency (FE) plots for the oxygen reduction to H2O2 catalyzed by the high-load Pt single-atom catalyst (sample II) prepared in Example 1 of this invention and the Co-defective cobalt selenide (sample I) prepared in steps (1)-(3) are shown. It can be seen that the hydrogen peroxide yield of the high-load Pt single-atom catalyst at 0 V vs. RHE is 225.5 mmol g. cat. -1 h -1 The Faraday efficiency was 86.2%. In contrast, the H2O2 yield of Co-defective cobalt selenide (Sample I) was lower at 0 V. vs. The hydrogen peroxide yield at RHE was 147.7 mmol / g. cat. -1 h -1 The Faraday efficiency is 85.4%. Therefore, the high-loading Pt single-atom catalyst further improves the acidity of 2e⁻. - ORR performance.
[0052] Example 2:
[0053] Steps (1) and (2) are the same as in Example 1;
[0054] In step (3), 0.0896 g of potassium thiocyanate white crystalline powder is added to the beaker, and the rest is the same as in Example 1;
[0055] (4) Weigh 0.2 g of the cobalt-defect-rich cobalt selenide powder prepared in step (3), and uniformly disperse it in a mixed solution of 30 mL of deionized water and ammonium hydroxide (NH3OH), and adjust the pH of the solution to 11. Then slowly add 10 mL of an ammonia solution containing tetraammineplatinum nitrate, the concentration of tetraammineplatinum nitrate in the ammonia solution being 0.015 mol / L, stir at room temperature for 24 h, then centrifuge, wash the precipitate with water four times by centrifugation, and then dry it in a vacuum oven at 80 ℃ for 12 h. Calcine the dried powder at 300 ℃ for 2 h in a mixed atmosphere of H2 / Ar (H2:Ar volume ratio of 5%:95%), with a heating rate of 5 ℃ / min, to obtain a high-load Pt single-atom catalyst.
[0056] Example 3:
[0057] Steps (1) and (2) are the same as in Example 1;
[0058] In step (3), 0.0448 g of potassium thiocyanate white crystalline powder is added to the beaker, and the rest is the same as in Example 1;
[0059] (4) Weigh 0.2 g of the cobalt-defect-rich cobalt selenide powder prepared in step (3), and uniformly disperse it in a mixed solution of 30 mL of deionized water and ammonium hydroxide (NH3OH), and adjust the pH of the solution to 13. Then slowly add 10 mL of an ammonia solution containing tetraammineplatinum nitrate, the concentration of tetraammineplatinum nitrate in the ammonia solution being 0.005 mol / L. Stir at room temperature for 24 h, then centrifuge. Wash the precipitate with water four times by centrifugation, and then dry it in a vacuum oven at 80 ℃ for 12 h. Calcine the dried powder at 300 ℃ for 2 h in a mixed atmosphere of H2 / Ar (H2:Ar volume ratio of 5%:95%), with a heating rate of 5 ℃ / min, to obtain a high-load Pt single-atom catalyst.
[0060] Example 4:
[0061] In step (4), the pH of the solution was adjusted to 13, the concentration of tetraammineplatinum nitrate in the ammonia solution was 0.15 mol / L, and the rest was the same as in Example 1.
[0062] The above description is merely an embodiment of the present invention and is not intended to limit the present invention in any way. The present invention can also have other embodiments based on the above structure and function, which will not be listed hereafter. Therefore, any simple modifications, equivalent changes, and alterations made by those skilled in the art to the above embodiments based on the technical essence of the present invention without departing from the scope of the present invention shall still fall within the scope of the present invention.
Claims
1. A method for preparing a cobalt-deficient cobalt selenide-anchored high-loading Pt single-atom catalyst, characterized in that... Specifically, the following steps are included: (1) Weigh a certain amount of selenium powder and add it to a NaOH solution with a concentration of 0.133 g / mL. Stir vigorously for 30-60 min to obtain mixture A; weigh a certain amount of cobalt nitrate hexahydrate and add it to an EDTA-2Na solution with a concentration of 0.25 mol / L. Stir vigorously for 30-60 min to obtain mixture B; (2) Add mixture B to mixture A and stir for 10-30 min to obtain mixture C. Transfer mixture C to a reactor for hydrothermal reaction. The temperature of the hydrothermal reaction is 200 °C and the reaction time is 6 h. After the hydrothermal reaction is completed, the reactor is naturally cooled to room temperature. Then, the product in the reactor is centrifuged and the black precipitate is collected and washed three times with hydrochloric acid solution. Then, it is washed with ultrapure water until the washing liquid is neutral. After that, the precipitate is collected and placed in a vacuum drying oven and dried at 60 °C for 24 h to obtain cobalt selenide powder. (3) Weigh a certain amount of cobalt selenide powder prepared in step (2), add it to a beaker containing anhydrous ethanol and disperse it, then add a certain amount of potassium thiocyanate powder to the beaker and stir vigorously for 30-60 min; then transfer the beaker to a cell disruptor and ultrasonically exfoliate at 40-50 ℃ for 2-4 h, with an ultrasonic power of 100-250 W, a centrifuge speed of 7500 rpm, and a centrifugation time of 4-6 min. Centrifuge the dispersion after ultrasonic exfoliation, wash the precipitate with anhydrous ethanol 5 times, collect the precipitate, transfer it to a vacuum drying oven for drying, and place the dried sample in a tube furnace and calcine at 300 ℃ for 2 h in an air atmosphere to obtain cobalt selenide rich in Co defects. (4) Weigh a certain amount of the Co-defect-rich cobalt selenide prepared in step (3), disperse it uniformly in an ammonium hydroxide aqueous solution, adjust the pH of the solution to 11~13, then slowly add a certain amount of ammonia solution containing tetraammineplatinum nitrate, stir at room temperature for 24 h, then centrifuge to separate, wash the precipitate with water by centrifugation, and then vacuum dry. The dried powder is calcined at 300 ℃ for 2 h in a H2 / Ar mixed atmosphere to obtain a cobalt defect-type cobalt selenide anchored high-load Pt single-atom catalyst.
2. The preparation method of the cobalt-defective cobalt selenide-anchored high-loading Pt single-atom catalyst as described in claim 1, characterized in that... The molar ratio of selenium powder to Co(NO3)2·6H2O is 2:
1.
3. The preparation method of the cobalt-defective cobalt selenide-anchored high-loading Pt single-atom catalyst as described in claim 1, characterized in that... The mass ratio of cobalt selenide powder to potassium thiocyanate powder added in step (3) is 1:0.04~0.
14.
4. The preparation method of the cobalt-defective cobalt selenide-anchored high-loading Pt single-atom catalyst as described in claim 1, characterized in that... The heating rate during roasting in steps (3) and (4) is 5 °C / min.
5. The preparation method of the cobalt-defective cobalt selenide-anchored high-loading Pt single-atom catalyst as described in claim 1, characterized in that... In step (4), the concentration of the ammonium hydroxide aqueous solution is 0.1 mol / L, and the mass ratio of the added Co-defect-rich cobalt selenide to the volume of the ammonium hydroxide aqueous solution is 1 g: 150 mL.
6. The method for preparing the cobalt-defective cobalt selenide-anchored high-loading Pt single-atom catalyst as described in claim 1 or 5, characterized in that... In step (4), the concentration of tetraammineplatinum nitrate in the ammonia solution is 0.005-0.15 mol / L, and the volume ratio of its addition to the volume of ammonium hydroxide solution is 1:
3.
7. The method for preparing the cobalt-defective cobalt selenide-anchored high-loading Pt single-atom catalyst as described in claim 1, characterized in that... In step (4), the volume percentages of H2 and Ar in the H2 / Ar mixed atmosphere are 5% and 95%, respectively.
8. The cobalt-defect cobalt selenide-anchored high-loading Pt single-atom catalyst prepared by the preparation method according to claim 1, characterized in that... It is in the form of nanosheets.
9. The application of the cobalt-defect cobalt selenide-anchored high-loading Pt single-atom catalyst prepared by the preparation method according to claim 1 in the electrocatalytic oxygen reduction to H2O2.
10. The application as described in claim 9, characterized in that... Cobalt-defective cobalt selenide-anchored high-loading Pt single-atom catalyst at 0 V vs The yield of hydrogen peroxide produced by electrocatalytic oxygen reduction under RHE was 225.5 mmol / g. cat. -1 h -1 .