A highly reconstituted ni-doped glassy MOFs electrocatalyst, preparation method and application thereof

Abstract

The application discloses a highly restructured Ni-doped glassy MOFs electrocatalyst and a preparation method and application thereof, a solution containing a cobalt salt and an organic ligand is subjected to a hydrothermal reaction to obtain ZIF-Co powder; the mixture of the ZIF-Co powder and a nickel source is used as a powder precursor; the powder precursor is loaded on an electrode material to obtain an electrode material loaded with the catalyst; and the electrode material loaded with the catalyst is subjected to glassification through a melt quenching technology, and then is restructured to obtain the highly restructured Ni-doped glassy MOFs electrocatalyst. The application promotes electrochemical surface restructuring by using the glassification, and obtains the glassy MOFs catalyst with rich active sites, thereby solving the problem that the active sites of the MOFs material are not easy to expose. In addition, the glassy MOFs can be directly fused and attached on the electrode material without a binder, thereby solving the problem that the powder catalyst is difficult to process, and facilitating device assembly and industrial scale production.

Description

Technical Field

[0001] This invention belongs to the field of electrocatalysis technology, and specifically relates to a highly reconstructed Ni-doped glassy MOF electrocatalyst, its preparation method, and its application. Background Technology

[0002] 5-Hydroxymethylfurfural (HMF) is considered one of the most versatile biomass platform molecules, capable of deriving a variety of high-value-added chemicals with important industrial applications. In particular, its oxidation product, 2,5-furandicarboxylic acid (FDCA), has high commercial value and can be used to manufacture many important polymer materials, finding wide applications in engineering plastics, pharmaceuticals, and textiles. Traditional thermocatalytic oxidation of HMF mostly requires noble metal-based catalysts to achieve FDCA yields of over 90%, involving high reaction temperatures and relatively high oxygen pressures, as well as some expensive and toxic organic reagents, which greatly limits the large-scale application of these systems. Electrocatalytic oxidation, as a newly developed method for FDCA preparation, is a "green" catalytic process that can selectively oxidize HMF to FDCA under ambient temperature and pressure conditions via anodic electrocatalytic oxidation. This method uses electrode potential and current density as two additional controllable parameters, enabling tunable substrate reactivity and high selectivity for the target product. More importantly, the HMF oxidation reaction (HMFOR) can replace the slow-kind oxygen evolution reaction (OER) and, when combined with the hydrogen evolution reaction (HER), significantly improve overall electrolysis efficiency, enabling the production of high-value chemicals.

[0003] Designing catalysts with fast reaction kinetics, strong oxidation equilibrium capabilities, and high selectivity is particularly important. Recent studies have shown that Co / Ni-based metal-organic frameworks (MOFs) possess enormous potential in electrocatalysis due to their structural and morphological diversity, rapid kinetics, and the coupling effect between Ni and Co. However, compared to some noble metal-based electrocatalysts, most of them still suffer from poor conductivity and insufficient intrinsic activity. Furthermore, many powdered MOF electrocatalysts require binders, which can not only clog active sites but also hinder assembly and fabrication for large-scale industrial applications. Summary of the Invention

[0004] To address the technical problem of low catalytic efficiency in existing catalysts, the present invention aims to provide a highly reconstructed Ni-doped glassy MOF electrocatalyst, its preparation method, and its application. The catalyst prepared by this method has more active sites, high catalytic effect, and due to its unique melting characteristics, the catalyst can be directly adhered to the electrode material, avoiding the difficulty in processing powdered MOF catalysts.

[0005] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0006] A method for preparing a highly reconstructed Ni-doped glassy MOF electrocatalyst includes the following steps:

[0007] ZIF-Co powder was obtained by hydrothermal reaction of a solution containing cobalt salt and organic ligand.

[0008] A mixture of ZIF-Co powder and a nickel source was used as a powder precursor;

[0009] A powder precursor is loaded onto an electrode material to obtain an electrode material loaded with a catalyst;

[0010] The electrode material with the catalyst was vitrified by melt quenching technology to obtain Ni-doped glassy ZIF-CoNi(g) precatalyst;

[0011] The Ni-doped glassy ZIF-CoNi(g) precatalyst was reconstructed to obtain a highly reconstructed Ni-doped glassy MOF electrocatalyst.

[0012] A further improvement of the present invention is that the cobalt salt is cobalt nitrate, the organic ligand is a mixture of imidazole and benzimidazole, the solvent in the solution is N,N-dimethylformamide, the nickel source is nickel acetylacetone, and the electrode material is copper foam, nickel foam, or carbon cloth.

[0013] A further improvement of the present invention is that the mass ratio of ZIF-Co powder to nickel acetylacetone is 4:1-16:1.

[0014] A further improvement of the present invention is that the molar ratio of imidazole to benzimidazole is 5:1-8:1; the molar ratio of organic ligand to cobalt salt is 2:1-4:1; and the mass ratio of cobalt salt to solvent is 1:60-1:120.

[0015] A further improvement of the present invention is that the hydrothermal reaction temperature is 120-150℃ and the time is 48-168h.

[0016] A further improvement of the present invention is that loading a powder precursor onto an electrode material to obtain a catalyst-loaded electrode material includes the following steps:

[0017] The electrode material is placed on the inner wall of a ball mill jar, a powder precursor is added, and the mixture is ball-milled to obtain an electrode material loaded with a catalyst.

[0018] A further improvement of this invention lies in vitrifying the catalyst-supported electrode material using a melt-quenching technique to obtain a Ni-doped glassy ZIF-CoNi(g) precatalyst, comprising the following steps:

[0019] The electrode material with the catalyst supported is placed in an inert gas atmosphere of argon or nitrogen and heated to 455-485℃ at a heating rate of 8-15℃ / min. After holding for 10-30min, it is cooled at a cooling rate of 5-10℃ / min to obtain Ni-doped glassy ZIF-CoNi(g) precatalyst.

[0020] A further improvement of this invention lies in reconstructing the Ni-doped glassy ZIF-CoNi(g) precatalyst to obtain a highly reconstructed Ni-doped glassy MOF electrocatalyst, comprising the following steps:

[0021] Ni-doped glassy ZIF-CoNi(g) precatalyst was subjected to multiple CV scans in a three-electrode system at standard hydrogen electrode potentials of 1.0–1.8 V to obtain a highly reconstructed Ni-doped glassy MOF electrocatalyst.

[0022] A highly reconstructed Ni-doped glassy MOF electrocatalyst.

[0023] Application of a highly reconstructed Ni-doped glassy MOF electrocatalyst in the electrooxidation of 5-hydroxymethylfurfural.

[0024] Compared with existing technologies, the present invention has the following advantages:

[0025] This invention is the first to introduce Ni into ZIF-Co to construct a novel glassy MOF catalyst. This catalyst exhibits glassy properties and contains Ni metal particles, providing more active sites and thus favoring electrocatalytic reactions. The vitrification strategy employed in this invention promotes the electrochemical reconstruction process. Due to the stronger charge transfer capacity and weaker Co-N bonding of the glassy ZIF-CoNi(g), the pre-catalyst undergoes deep reconstruction, resulting in abundant active sites and excellent HMF electro-oxidation performance. The proposed method for preparing a highly reconstructed Ni-doped glassy MOF electrocatalyst utilizes simple equipment, mild reaction conditions, low cost, and is easy to control, requiring no toxic or harmful reagents, thus facilitating the industrialization and engineering application of the catalyst.

[0026] Furthermore, in this invention, the vitrification process is a crucial factor determining catalyst performance. This process is achieved through melt quenching technology to induce a disordered state in the Co-N bonds and weaken their bond energy, which is beneficial for subsequent electrochemical reconstruction. Therefore, precisely controlling the heating temperature and the rates of heating and cooling are indispensable elements for optimizing the vitrification effect and thus improving catalyst performance.

[0027] Furthermore, the amount of Ni doping has a significant impact on catalyst performance; the addition of an appropriate amount of Ni can effectively increase the number of active sites, thereby enhancing catalytic activity. However, when Ni is excessively doped, it not only fails to further improve catalytic performance but may also interfere with the original Co active sites, leading to a decline in performance. Therefore, optimizing the ratio of Co to Ni atoms is key to improving the overall performance of the catalyst.

[0028] The glassy electrocatalyst prepared by this invention is molten and adhered to the surface of the electrode material, making full contact without the need for additional binders, and does not cover the reactive active sites. At the same time, it achieves rapid charge transfer, solving the problem of difficult processing of powdered MOF catalysts. Attached Figure Description

[0029] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments recorded in this application. For those skilled in the art, other drawings can be obtained based on these drawings without any creative effort.

[0030] Figure 1 This invention provides a schematic diagram of the preparation principle of R-ZIF-CoNi(g).

[0031] Figure 2 The image shows a scanning electron microscope (SEM) image of ZIF-Co obtained in Comparative Example 1 of this invention.

[0032] Figure 3 The image shown is a scanning electron microscope image of ZIF-Co(g) obtained in Comparative Example 1 of this invention.

[0033] Figure 4 The image shown is a scanning electron microscope image of R-ZIF-Co(g) obtained in Comparative Example 1 of this invention.

[0034] Figure 5 The ZIF-CoNi obtained in Example 2 of this invention 0.1 The scanning electron microscope images; where (a) is at low magnification and (b) is at high magnification;

[0035] Figure 6 The ZIF-CoNi obtained in Example 2 of this invention 0.1 (g) is a scanning electron microscope image; where (a) is at a low magnification and (b) is at a high magnification.

[0036] Figure 7 The R-ZIF-CoNi obtained in Example 2 of this invention 0.1 (g) scanning electron microscope image;

[0037] Figure 8 The X-ray diffraction pattern of the catalyst obtained in Example 2 of this invention;

[0038] Figure 9 The cyclic voltammetry curves of the catalysts obtained in Example 2 and Comparative Example 2 of this invention are shown below.

[0039] Figure 10 Linear sweep voltammetry curves of the catalysts obtained in Examples 1-3 and Comparative Examples 1-2 of this invention;

[0040] Figure 11 The R-ZIF-CoNi obtained in Example 2 of this invention 0.1 (g) Current-time diagram of the catalyst electrolysis of HMF;

[0041] Figure 12 The R-ZIF-CoNi obtained in Example 2 and Comparative Example 2 of this invention 0.1 (g), R-ZIF-CoNi 0.1 The conversion (con.) of HMF, the yield (yield) of FDCA, and the Faraday efficiency (FE) of FDCA after the catalytic electrolysis of HMF.

[0042] Figure 13 The R-ZIF-CoNi obtained in Example 2 of this invention 0.1 (g) Cyclic stability plot of HMF electro-oxidation of catalyst with respect to HMF conversion, FDCA yield and Faraday efficiency of FDCA. Detailed Implementation

[0043] To facilitate understanding of the present invention, a more complete description will be given below with reference to the accompanying drawings. Preferred embodiments of the invention are shown in the drawings. However, the invention can be implemented in many different forms and is not limited to the embodiments described herein. Rather, these embodiments are provided to provide a thorough and complete understanding of the disclosure of the invention.

[0044] Glassy MOFs, as emerging materials, have attracted increasing attention due to their high porosity, excellent ionic conductivity, and charge transfer capabilities. Furthermore, recent studies have shown that many MOF electrocatalysts undergo surface reconstruction under electro-oxidation conditions, forming actual active sites and exhibiting superior catalytic performance. Therefore, glassy MOFs hold promise as highly efficient catalysts for the electro-oxidation of HMFs, as their disordered amorphous structure may facilitate surface reconstruction and the formation of abundant active species.

[0045] This invention provides a method for preparing a highly reconstructed Ni-doped glassy MOF electrocatalyst and its application in HMF electrooxidation, overcoming the technical shortcomings of existing catalysts such as low catalytic efficiency, insufficient active sites, low electron transfer efficiency, difficulty in processing powder form, and the need for binders. The highly reconstructed Ni-doped glassy MOF electrocatalyst prepared by this invention has abundant active sites and excellent catalytic activity, and can also be directly melt-loaded onto the surface of electrode materials, possessing potential for industrial application.

[0046] The present invention discloses a method for preparing a highly reconstructed Ni-doped glassy MOF electrocatalyst, comprising the following steps:

[0047] Metal salt (cobalt nitrate) and organic ligand (a mixture of imidazole and benzimidazole) were added to N,N-dimethylformamide solvent and stirred for 30-80 min. The molar ratio of imidazole to benzimidazole was 5:1-8:1, the molar ratio of organic ligand to metal salt was 2:1-4:1, and the mass ratio of metal salt to N,N-dimethylformamide was 1:60-1:120. The mixture was transferred to a high-pressure reactor and heated at 120-150℃ for 48-168 h. The product was washed 3-5 times with N,N-dimethylformamide or methanol, centrifuged, and dried to obtain ZIF-Co powder.

[0048] ZIF-Co powder and nickel acetylacetonate were mixed and ground evenly in a mortar at a mass ratio of 4:1 to 16:1 to obtain the powder precursor ZIF-CoNi.

[0049] Select cleaned electrode materials (foamed copper, foamed nickel, or carbon cloth), cut them to the appropriate size, and attach them to the inner wall of a ball mill jar. Use zirconia ball milling beads with diameters of 1.2 mm and 3.2 mm, with masses of 2-6 g and 16-20 g respectively, and 50-100 g of powder precursor powder. Ball mill the loaded powder catalyst at a speed of 350-450 rpm for 5 min to obtain electrode materials with good catalyst loading. Place the electrode materials with good catalyst loading in a tube furnace under an inert gas atmosphere of argon or nitrogen, and rapidly heat them to 455-485 °C at a heating rate of 8-15 °C / min to melt them. After holding the temperature for 10-30 min, rapidly cool them at a cooling rate of 5-10 °C / min to vitrify them, thus obtaining Ni-doped glassy ZIF-CoNi(g) precatalyst.

[0050] The Ni-doped glassy ZIF-CoNi(g) precatalyst was electrochemically reconstructed by cyclic voltammetry scans in a three-electrode system. Specifically, the precatalyst was reconstructed using cyclic voltammetry with scanning parameters set to 100-200 cycles at a scan rate of 100 mV / s at a standard hydrogen electrode potential of 1.0–1.8 V, resulting in a highly reconstructed Ni-doped glassy MOF electrocatalyst, namely the R-ZIF-CoNi(g) electrocatalyst.

[0051] A highly reconstructed Ni-doped glassy MOF electrocatalyst was prepared according to the method described above.

[0052] Application of a highly reconstructed Ni-doped glassy MOF electrocatalyst as described above in the electrooxidation of 5-hydroxymethylfurfural (HMF).

[0053] Figure 1 A schematic diagram illustrating the preparation principle of the R-ZIF-CoNi(g) electrocatalyst provided by this invention. See also... Figure 1 First, the precursors ZIF-62(Co) (ZIF-Co) and nickel acetylacetone (Ni(acac)2) are thoroughly ground and mixed. Then, glassy ZIF-CoNi (ZIF-CoNi(g)) is deposited on copper foam (CF) by a two-step method of ball milling and melt quenching. Subsequently, it is reconstructed by cyclic voltammetry (CV) to obtain electrochemically reconstructed ZIF-CoNi(g), namely R-ZIF-CoNi(g) electrocatalyst.

[0054] The HMF electro-oxidation performance of Examples 1-3 and Comparative Examples 1-2 was tested in a typical H-type electrolytic cell three-electrode system, using conductive substrates (0.9 × 0.9 cm) loaded with different materials. 2) The HMF was used directly as the working electrode, with a carbon rod as the counter electrode and Hg / HgO as the reference electrode. The electrolyte solution was 1.0 mol / L KOH containing 10 mmol / L HMF. The potential during the test can be converted into the reversible hydrogen electrode potential E(RHE) using the Stearns equation. The HMF electrolysis products of Examples 1-3 and Comparative Examples 1-2 were analyzed by long-term electrolysis at 1.48 V vs. RHE, with 30 mL of 1.0 mol / L KOH solution containing 10 mmol / L HMF in the electrolyte. Samples were taken from the anode at regular intervals and analyzed by high-performance liquid chromatography (HPLC).

[0055] The present invention is further illustrated by the following embodiments, which provide a better understanding of the invention. However, those skilled in the art will readily understand that the specific material ratios, process conditions, and results described in the embodiments are for illustrative purposes only and should not, and will not, limit the invention as described in detail in the claims.

[0056] Example 1

[0057] Step 1) Add 4 mmol cobalt nitrate, 11.6 mmol imidazole and 1.6 mmol benzimidazole to 90 mL N,N-dimethylformamide solvent and stir for 60 min. Transfer the mixture to a high-pressure reactor and heat at 130 °C for 168 h. Wash the product three times with N,N-dimethylformamide, centrifuge, and vacuum dry at 70 °C for 12 h to obtain ZIF-Co powder.

[0058] Step 2) Mix ZIF-Co and nickel acetylacetonate at a mass ratio of 16:1 and grind them evenly to obtain ZIF-CoNi. 0.05 ;

[0059] Step 3) Select cleaned copper foam, cut to size, and attach it to the inner wall of the ball mill jar. Use zirconia grinding beads with diameters of 1.2 mm and 3.2 mm, weighing 4 g and 18 g respectively, and 60 g of catalyst powder. Ball mill the loaded powder catalyst at 400 rpm for 5 min. Place the catalyst-loaded electrode material in a tube furnace under an argon atmosphere and rapidly heat it to 470 °C at a heating rate of 10 °C / min to melt it. Hold it for 20 min, then rapidly cool it at a cooling rate of 10 °C / min to vitrify it, obtaining Ni-doped glassy ZIF-CoNi. 0.05 (g) Precatalyst;

[0060] Step 4) In a three-electrode system, the pre-catalyst is reconstructed using cyclic voltammetry with parameters set to 1.0–1.8 V and a scan rate of 100 mV / s for 100 cycles to obtain the reconstructed glassy catalyst, denoted as R-ZIF-CoNi. 0.05 (g)

[0061] from Figure 10 The sex scan voltammetry (LSV) curve shows R-ZIF-CoNi 0.05 (g) exhibits good HMF electro-oxidation performance at 10 mA cm⁻¹. -2 The potential required at this current density is only 1.365 V vs. RHE. Compared with Comparative Example 1, the potential of this electrocatalyst is reduced, indicating that Ni doping can effectively promote the reaction.

[0062] Example 2

[0063] Step 1) Add 4 mmol cobalt nitrate, 11.6 mmol imidazole and 1.6 mmol benzimidazole to 90 mL N,N-dimethylformamide solvent and stir for 60 min. Transfer the mixture to a high-pressure reactor and heat at 130 °C for 168 h. Wash the product three times with N,N-dimethylformamide, centrifuge, and vacuum dry at 70 °C for 12 h to obtain ZIF-Co powder.

[0064] Step 2) Mix ZIF-Co and nickel acetylacetonate at a mass ratio of 8:1 and grind them evenly to obtain ZIF-CoNi. 0.1 ;

[0065] Step 3) Select cleaned copper foam, cut to size, and attach it to the inner wall of the ball mill jar. Use zirconia grinding beads with diameters of 1.2 mm and 3.2 mm, weighing 4 g and 18 g respectively, and 60 g of catalyst powder. Ball mill the loaded powder catalyst at 400 rpm for 5 min. Place the catalyst-loaded electrode material in a tube furnace under an argon atmosphere and rapidly heat it to 470 °C at a heating rate of 10 °C / min to melt it. Hold it for 20 min, then rapidly cool it at a cooling rate of 10 °C / min to vitrify it, obtaining Ni-doped glassy ZIF-CoNi. 0.1 (g) Precatalyst;

[0066] Step 4) In a three-electrode system, the pre-catalyst is reconstructed using cyclic voltammetry with parameters set to 1.0–1.8 V and a scan rate of 100 mV / s for 100 cycles to obtain the reconstructed glassy catalyst, denoted as R-ZIF-CoNi. 0.1 (g)

[0067] Figure 5 In Figures (a) and (b), ZIF-CoNi is shown in this embodiment. 0.1 The scanning electron microscope image clearly shows the catalyst particles supported on the copper foam.

[0068] Figure 6 In Figures (a) and (b), ZIF-CoNi is shown in this embodiment. 0.1 The scanning electron microscope image (g) clearly shows the catalyst molten and supported on the copper foam.

[0069] Figure 7 The R-ZIF-CoNi in this embodiment 0.1 The scanning electron microscope image of (g) clearly shows that many lamellar structures appear on the reconstructed surface, forming new active centers.

[0070] Figure 8 This is the X-ray diffraction (XRD) pattern of the catalyst in this embodiment, ZIF-CoNi. 0.1 It exhibits a crystalline structure; ZIF-CoNi0.1 (g) It exhibits an amorphous state, which is a long-range disordered glassy structure.

[0071] from Figure 10 The sex scan voltammetry (LSV) curve shows R-ZIF-CoNi0 .1 (g) exhibits good HMF electro-oxidation performance at 10 mA cm⁻¹. -2 The potential required at this current density is only 1.36 V vs. RHE. Compared to Example 1, the potential of this electrocatalyst is further reduced, indicating that increasing the amount of Ni doping improves the catalytic activity.

[0072] Example 3

[0073] Step 1) Add 4 mmol cobalt nitrate, 11.6 mmol imidazole and 1.6 mmol benzimidazole to 90 mL N,N-dimethylformamide solvent and stir for 60 min. Transfer the mixture to a high-pressure reactor and heat at 130 °C for 168 h. Wash the product three times with N,N-dimethylformamide, centrifuge, and vacuum dry at 70 °C for 12 h to obtain ZIF-Co powder.

[0074] Step 2) Mix ZIF-Co and nickel acetylacetonate at a mass ratio of 16:3 and grind them evenly to obtain ZIF-CoNi. 0.15 ;

[0075] Step 3) Select cleaned copper foam, cut to size, and attach it to the inner wall of the ball mill jar. Use zirconia grinding beads with diameters of 1.2 mm and 3.2 mm, weighing 4 g and 18 g respectively, and 60 g of catalyst powder. Ball mill the loaded powder catalyst at 400 rpm for 5 min. Place the catalyst-loaded electrode material in a tube furnace under an argon atmosphere and rapidly heat it to 470 °C at a heating rate of 10 °C / min to melt it. Hold it for 20 min, then rapidly cool it at a cooling rate of 10 °C / min to vitrify it, obtaining Ni-doped glassy ZIF-CoNi. 0.15 (g) Precatalyst;

[0076] Step 4) In a three-electrode system, the pre-catalyst is reconstructed using cyclic voltammetry with parameters set to 1.0–1.8 V and a scan rate of 100 mV / s for 100 cycles to obtain the reconstructed glassy catalyst, denoted as R-ZIF-CoNi. 0.15 (g)

[0077] from Figure 10 The sex scan voltammetry (LSV) curve shows R-ZIF-CoNi 0.15 (g) exhibits good HMF electro-oxidation performance at 10 mA cm⁻¹. -2The potential required at the specified current density is only 1.36 V vs. RHE. Compared to Example 2, the potential of this electrocatalyst did not change, indicating that further increasing the amount of Ni doping did not contribute to the catalytic activity.

[0078] Comparative Example 1

[0079] Step 1) Add 4 mmol cobalt nitrate, 11.6 mmol imidazole and 1.6 mmol benzimidazole to 90 mL N,N-dimethylformamide solvent and stir for 60 min. Transfer the mixture to a high-pressure reactor and heat at 130 °C for 168 h. Wash the product three times with N,N-dimethylformamide, centrifuge, and vacuum dry at 70 °C for 12 h to obtain ZIF-Co powder.

[0080] Step 2) Select cleaned copper foam, cut it to the desired size, and attach it to the inner wall of the ball mill jar. Use zirconia ball milling beads with diameters of 1.2 mm and 3.2 mm, with masses of 4 g and 18 g respectively, and 60 g of catalyst powder. Ball mill the loaded powder catalyst at 400 rpm for 5 min. Place the electrode material loaded with catalyst in a tube furnace under an argon atmosphere and rapidly heat it to 470 °C at a heating rate of 10 °C / min to melt it. After holding it for 20 min, rapidly cool it at a cooling rate of 10 °C / min to vitrify it, and obtain a glassy ZIF-Co(g) precatalyst.

[0081] Step 3) In a three-electrode system, the pre-catalyst is reconstructed using cyclic voltammetry with parameters set to 1.0–1.8 V and cyclically 100 times at a scan rate of 100 mV / s to obtain the reconstructed glassy electrocatalyst, denoted as R-ZIF-Co(g).

[0082] The MOF structure of the glassy electrocatalyst in this comparative example is ZIF-62(Co)[Co(Im)]. 1.75 (bIm) 0.25 The catalyst has a melting point of 425℃ and a glass transition temperature of 365℃. Compared to the crystalline state, glassy MOFs have disordered and weaker Co-N bonds, making them more prone to reconstruction. The reconstructed R-ZIF-Co(g) has abundant active sites.

[0083] Figure 2 The scanning electron microscope image of ZIF-Co in this comparative example clearly shows the catalyst particles supported on the copper foam.

[0084] Figure 3 The scanning electron microscope image of ZIF-Co(g) in this comparative example clearly shows the catalyst molten and supported on the copper foam.

[0085] Figure 4The scanning electron microscope image of R-ZIF-Co(g) in this comparative example clearly shows that a lamellar structure appears on the surface after reconstruction, forming new active centers.

[0086] Figure 10 This corresponds to the linear sweep volt-ampere (LSV) curve. At a current density of 10 mA / cm²... -2 At the given location, the potentials of the R-ZIF-Co(g) electrocatalyst were 1.380 V vs. RHE, demonstrating good HMF electro-oxidation performance.

[0087] Comparative Example 2

[0088] Step 1) Add 4 mmol cobalt nitrate, 11.6 mmol imidazole and 1.6 mmol benzimidazole to 90 mL N,N-dimethylformamide solvent and stir for 60 min. Transfer the mixture to a high-pressure reactor and heat at 130 °C for 168 h. Wash the product three times with N,N-dimethylformamide, centrifuge, and vacuum dry at 70 °C for 12 h to obtain ZIF-Co powder.

[0089] Step 2) Mix ZIF-Co and nickel acetylacetonate at a mass ratio of 8:1 and grind them evenly to obtain ZIF-CoNi. 0.1 ;

[0090] Step 3) Select the cleaned foam copper, cut it to the desired size, and attach it to the inner wall of the ball mill jar. Use zirconia ball milling beads with diameters of 1.2 mm and 3.2 mm, with masses of 4 g and 18 g respectively, and 60 g of catalyst powder. Ball mill the loaded powder catalyst at 400 rpm for 5 min.

[0091] Step 4) In a three-electrode system, the pre-catalyst is reconstructed using cyclic voltammetry with parameters set to 1.0–1.8 V and a scan rate of 100 mV / s for 100 cycles to obtain the reconstructed catalyst, denoted as R-ZIF-CoNi. 0.1 .

[0092] Figure 9 These are the cyclic voltammograms of the catalysts in Example 2 and Comparative Example 2. During cycling, the ZIF-CoNi... 0.1 and ZIF-CoNi 0.1 The curves for (g) all showed a significant increase, which is attributed to the dynamic electrochemical reconstruction process. This is similar to the ZIF-CoNi... 0.1 In comparison, ZIF-CoNi 0.1 (g) exhibited a stronger oxidation peak and higher current density after 100 cycles, indicating that glass transition promoted surface reconstruction.

[0093] from Figure 10The sex scan voltammetry (LSV) curve shows R-ZIF-CoNi 0.1 Catalyst at 10 mAcm -2 The potential required at the specified current density is 1.4V vs. RHE. The potential of this electrocatalyst is significantly higher than that of Examples 1-3 and Comparative Example 1, indicating that vitrification is an important factor affecting catalytic activity. Vitrification can promote the formation of more active centers during the reconstruction process, which is beneficial to the HMF reaction.

[0094] Figure 11 The current-time graph of the HMF electrolysis process shows that the R-ZIF-CoNi prepared in Example 2 of this invention... 0.1 The HMF electro-oxidation process of (g) requires only 160 min of electrolysis time, demonstrating superior reaction performance.

[0095] Figure 12 The graphs show the HMF conversion rate, FDCA yield, and FDCA Faraday efficiency of the HMF electrolysis process. The R-ZIF-CoNi prepared in Example 2 and Comparative Example 2 of this invention... 0.1 (g) and R-ZIF-CoNi 0.1 The final HMF conversions were 100% and 93%, respectively; the FDCA yields were 99.6% and 91.3%, respectively; and the FDCA Faraday efficiencies were 98.5% and 90.1%, respectively. This demonstrates that the vitrified catalyst can provide more catalytic active sites and exhibits excellent performance.

[0096] Figure 13 R-ZIF-CoNi prepared in Example 2 of this invention 0.1 (g) After seven cycles of HMF electro-oxidation catalysis, the HMF conversion, FDCA yield and FDCA Faradaic efficiency did not decrease significantly, demonstrating excellent catalytic cycle stability.

[0097] Example 4

[0098] Step 1) Add 4 mmol of cobalt nitrate, imidazole, and benzimidazole to N,N-dimethylformamide solvent and stir for 30 min. Transfer the mixture to a high-pressure reactor and heat at 150 °C for 48 h. Wash the product three times with N,N-dimethylformamide, centrifuge, and vacuum dry at 70 °C for 12 h to obtain ZIF-Co powder. The molar ratio of imidazole to benzimidazole is 5:1, the molar ratio of the total amount of imidazole and benzimidazole to cobalt nitrate is 4:1, and the mass ratio of cobalt nitrate to N,N-dimethylformamide is 1:60.

[0099] Step 2) Mix ZIF-Co and nickel acetylacetonate at a mass ratio of 5:1 and grind them evenly to obtain ZIF-CoNi;

[0100] Step 3) Select cleaned copper foam, cut it to the desired size, and attach it to the inner wall of the ball mill jar. Use zirconia ball milling beads with diameters of 1.2 mm and 3.2 mm, with masses of 2 g and 18 g respectively, and 50 g of catalyst powder. Ball mill the loaded powder catalyst at 400 rpm for 5 min. Place the electrode material loaded with catalyst in a tube furnace under an argon atmosphere and rapidly heat it to 465 °C at a heating rate of 8 °C / min to melt it. After holding it for 20 min, rapidly cool it at a cooling rate of 8 °C / min to vitrify it, thus obtaining Ni-doped glassy ZIF-CoNi(g) precatalyst.

[0101] Step 4) In a three-electrode system, the precatalyst was reconstructed using cyclic voltammetry with parameters set to 1.0–1.8 V and cyclically repeated 150 times at a scan rate of 100 mV / s to obtain the R-ZIF-CoNi(g) electrocatalyst.

[0102] Example 5

[0103] Step 1) Add 4 mmol of cobalt nitrate, imidazole, and benzimidazole to N,N-dimethylformamide solvent and stir for 40 min. Transfer the mixture to a high-pressure reactor and heat at 140 °C for 72 h. Wash the product three times with N,N-dimethylformamide, centrifuge, and vacuum dry at 70 °C for 12 h to obtain ZIF-Co powder. The molar ratio of imidazole to benzimidazole is 8:1, the molar ratio of the total amount of imidazole and benzimidazole to cobalt nitrate is 7:2, and the mass ratio of cobalt nitrate to N,N-dimethylformamide is 1:100.

[0104] Step 2) Mix ZIF-Co and nickel acetylacetonate at a mass ratio of 7:1 and grind them evenly to obtain ZIF-CoNi;

[0105] Step 3) Select cleaned copper foam, cut it to the desired size, and attach it to the inner wall of the ball mill jar. Use zirconia ball milling beads with diameters of 1.2 mm and 3.2 mm, with masses of 3 g and 17 g respectively, and 100 g of catalyst powder. Ball mill the loaded powder catalyst at 420 rpm for 5 min. Place the electrode material loaded with catalyst in a tube furnace under an argon atmosphere and rapidly heat it to 480 °C at a heating rate of 18 °C / min to melt it. After holding it for 15 min, rapidly cool it at a cooling rate of 15 °C / min to vitrify it, thus obtaining Ni-doped glassy ZIF-CoNi(g) precatalyst.

[0106] Step 4) In a three-electrode system, the precatalyst is reconstructed using cyclic voltammetry with parameters set to 1.0–1.8 V and cyclically repeated 200 times at a scan rate of 100 mV / s until stable, to obtain the R-ZIF-CoNi(g) electrocatalyst.

[0107] Example 6

[0108] Step 1) Add 4 mmol of cobalt nitrate, imidazole, and benzimidazole to N,N-dimethylformamide solvent and stir for 60 min. Transfer the mixture to a high-pressure reactor and heat at 130 °C for 120 h. Wash the product three times with N,N-dimethylformamide, centrifuge, and vacuum dry at 70 °C for 12 h to obtain ZIF-Co powder. The molar ratio of imidazole to benzimidazole is 6:1, the molar ratio of the total amount of imidazole and benzimidazole to cobalt nitrate is 5:2, and the mass ratio of cobalt nitrate to N,N-dimethylformamide is 1:70.

[0109] Step 2) Mix ZIF-Co and nickel acetylacetonate at a mass ratio of 13:1 and grind them evenly to obtain ZIF-CoNi;

[0110] Step 3) Select cleaned copper foam, cut it to the desired size, and attach it to the inner wall of the ball mill jar. Use zirconia ball milling beads with diameters of 1.2 mm and 3.2 mm, with masses of 4 g and 18 g respectively, and 70 g of catalyst powder. Ball mill the loaded powder catalyst at 370 rpm for 5 min. Place the electrode material loaded with catalyst in a tube furnace under an argon atmosphere and rapidly heat it to 470 °C at a heating rate of 12 °C / min to melt it. After holding it for 20 min, rapidly cool it at a cooling rate of 12 °C / min to vitrify it, and obtain Ni-doped glassy ZIF-CoNi(g) precatalyst.

[0111] Step 4) In a three-electrode system, the precatalyst was reconstructed using cyclic voltammetry with parameters set to 1.0–1.8 V and cyclically repeated 120 times at a scan rate of 100 mV / s to obtain the R-ZIF-CoNi(g) electrocatalyst.

[0112] Example 7

[0113] Step 1) Add 4 mmol of cobalt nitrate, imidazole, and benzimidazole to N,N-dimethylformamide solvent and stir for 70 min. Transfer the mixture to a high-pressure reactor and heat at 120 °C for 140 h. Wash the product three times with N,N-dimethylformamide, centrifuge, and vacuum dry at 70 °C for 12 h to obtain ZIF-Co powder. The molar ratio of imidazole to benzimidazole is 7:1, the molar ratio of the total amount of imidazole and benzimidazole to cobalt nitrate is 7:2, and the mass ratio of cobalt nitrate to N,N-dimethylformamide is 1:80.

[0114] Step 2) Mix ZIF-Co and nickel acetylacetonate at a mass ratio of 12:1 and grind them evenly to obtain ZIF-CoNi;

[0115] Step 3) Select cleaned copper foam, cut it to the desired size, and attach it to the inner wall of the ball mill jar. Use zirconia ball milling beads with diameters of 1.2 mm and 3.2 mm, with masses of 5 g and 16 g respectively, and 90 g of catalyst powder. Ball mill the loaded powder catalyst at 400 rpm for 5 min. Place the electrode material loaded with catalyst in a tube furnace under an argon atmosphere and rapidly heat it to 460 °C at a heating rate of 13 °C / min to melt it. After holding it for 30 min, rapidly cool it at a cooling rate of 13 °C / min to vitrify it, and obtain Ni-doped glassy ZIF-CoNi(g) precatalyst.

[0116] Step 4) In a three-electrode system, the precatalyst was reconstructed using cyclic voltammetry with parameters set to 1.0–1.8 V and cyclically 180 times at a scan rate of 100 mV / s to obtain the R-ZIF-CoNi(g) electrocatalyst.

[0117] Example 8

[0118] Step 1) Add 4 mmol of cobalt nitrate, imidazole, and benzimidazole to N,N-dimethylformamide solvent and stir for 80 min. Transfer the mixture to a high-pressure reactor and heat at 120 °C for 168 h. Wash the product 5 times with N,N-dimethylformamide, centrifuge, and vacuum dry at 70 °C for 12 h to obtain ZIF-Co powder. The molar ratio of imidazole to benzimidazole is 8:1, the molar ratio of the total amount of imidazole and benzimidazole to cobalt nitrate is 3:1, and the mass ratio of cobalt nitrate to N,N-dimethylformamide is 1:120.

[0119] Step 2) Mix ZIF-Co and nickel acetylacetonate at a mass ratio of 4:1 and grind them evenly to obtain ZIF-CoNi. 0.2 ;

[0120] Step 3) Select cleaned copper foam, cut to size, and attach it to the inner wall of the ball mill jar. Use zirconia grinding beads with diameters of 1.2 mm and 3.2 mm, weighing 6 g and 19 g respectively, and 80 g of catalyst powder. Ball mill the loaded catalyst at 450 rpm for 5 min. Place the catalyst-loaded electrode material in a tube furnace under an argon atmosphere and rapidly heat it to 485 °C at a heating rate of 14 °C / min to melt it. Hold it for 10 min, then rapidly cool it at a cooling rate of 14 °C / min to vitrify it, obtaining Ni-doped glassy ZIF-CoNi. 0.2 (g) Precatalyst;

[0121] Step 4) In a three-electrode system, the pre-catalyst was reconstructed using cyclic voltammetry with parameters set to 1.0–1.8 V and a scan rate of 100 mV / s for 170 cycles to obtain R-ZIF-CoNi. 0.2 (g) Electrocatalyst.

[0122] Example 9

[0123] Step 1) Add 4 mmol of cobalt nitrate, imidazole, and benzimidazole to N,N-dimethylformamide solvent and stir for 50 min. Transfer the mixture to a high-pressure reactor and heat at 135 °C for 96 h. Wash the product with N,N-dimethylformamide four times, centrifuge, and vacuum dry at 70 °C for 12 h to obtain ZIF-Co powder. The molar ratio of imidazole to benzimidazole is 5:1, the molar ratio of the total amount of imidazole and benzimidazole to cobalt nitrate is 2:1, and the mass ratio of cobalt nitrate to N,N-dimethylformamide is 1:120.

[0124] Step 2) Mix ZIF-Co and nickel acetylacetonate at a mass ratio of 8:1 and grind them evenly to obtain ZIF-CoNi;

[0125] Step 3) Select cleaned copper foam, cut it to the desired size, and attach it to the inner wall of the ball mill jar. Use zirconia ball milling beads with diameters of 1.2 mm and 3.2 mm, with masses of 4 g and 20 g respectively, and 70 g of catalyst powder. Ball mill the loaded powder catalyst at 350 rpm for 5 min. Place the electrode material loaded with catalyst in a tube furnace under an argon atmosphere and rapidly heat it to 455 °C at a heating rate of 11 °C / min to melt it. After holding it for 30 min, rapidly cool it at a cooling rate of 11 °C / min to vitrify it, and obtain Ni-doped glassy ZIF-CoNi(g) precatalyst.

[0126] Step 4) In a three-electrode system, the precatalyst was reconstructed using cyclic voltammetry with parameters set to 1.0–1.8 V and cyclically repeated 130 times at a scan rate of 100 mV / s to obtain the R-ZIF-CoNi(g) electrocatalyst.

[0127] In this invention, the vitrification process is a crucial factor determining catalyst performance. This process is achieved through melt quenching technology to induce a disordered state in the Co-N bonds and weaken their bond energy, which is beneficial for subsequent electrochemical reconstruction. Therefore, precisely controlling the heating temperature and the rates of heating and cooling are indispensable elements for optimizing the vitrification effect and thus improving catalyst performance. Furthermore, the amount of Ni doping has a significant impact on catalyst performance; the addition of an appropriate amount of Ni can effectively increase the number of active sites, thereby enhancing catalytic activity. However, when Ni doping is excessive, it not only fails to further improve catalytic performance but may also interfere with the original Co active sites, leading to a decline in performance. Therefore, optimizing the ratio of Co to Ni atoms is key to improving the overall performance of the catalyst.

[0128] This invention utilizes vitrification to promote electrochemical surface reconstruction, thereby obtaining glassy MOFs catalysts with abundant active sites. This solves the problem that the active sites of MOFs materials are not easily exposed. In addition, glassy MOFs can be directly melted and attached to electrode materials without the need for binders, solving the problem of difficult processing of powdered catalysts and facilitating device assembly and industrial-scale production.

[0129] The above description is only of the preferred embodiment of the present invention and should not be construed as limiting the scope of the claims. The present invention is not limited to the above embodiments, and variations in its specific structure are permitted. All variations made within the scope of the independent claims of the present invention are also within the scope of protection of the present invention.

[0130] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. The terminology used herein in the description of the invention is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. The term "and / or" as used herein includes any and all combinations of one or more of the associated listed items.

Claims

1. A method for preparing a highly reconstituted Ni-doped glassy MOFs electrocatalyst, characterized in that, The method comprises the following steps: a solution containing a cobalt salt and an organic ligand is subjected to a hydrothermal reaction to obtain a ZIF-Co powder; a mixture of the ZIF-Co powder and a nickel source is used as a powder precursor; the powder precursor is loaded on an electrode material to obtain an electrode material loaded with a catalyst; the electrode material loaded with the catalyst is subjected to glassification by a melt quenching technique to obtain a glassy ZIF-CoNi(g) pre-catalyst doped with nickel; the glassy ZIF-CoNi(g) pre-catalyst doped with nickel is restructured to obtain a highly restructured Ni-doped glassy MOFs electrocatalyst; the electrode material loaded with the catalyst is subjected to glassification by a melt quenching technique to obtain a glassy ZIF-CoNi(g) pre-catalyst doped with nickel, comprising the following steps: the electrode material loaded with the catalyst is placed in an argon or nitrogen inert gas atmosphere, heated to 455-485℃ at a heating rate of 8-15℃ / min, kept for 10-30min, and then cooled at a cooling rate of 5-10℃ / min to obtain the glassy ZIF-CoNi(g) pre-catalyst doped with nickel; the glassy ZIF-CoNi(g) pre-catalyst doped with nickel is restructured to obtain a highly restructured Ni-doped glassy MOFs electrocatalyst, comprising the following steps: the glassy ZIF-CoNi(g) pre-catalyst doped with nickel is subjected to cyclic multiple CV scans under a three-electrode system at a standard hydrogen electrode potential of 1.0-1.8 V to obtain the highly restructured Ni-doped glassy MOFs electrocatalyst.

2. The method of claim 1, wherein the highly reconstructed Ni-doped glassy MOFs electrocatalyst is prepared by the method comprising: The cobalt salt is cobalt nitrate, the organic ligand is a mixture of imidazole and benzimidazole, the solvent in the solution is N,N-dimethylformamide, and the nickel source is nickel acetylacetonate; the electrode material is copper foam, nickel foam or carbon cloth.

3. The method of claim 2, wherein the highly reconstructed Ni-doped glassy MOFs electrocatalyst is prepared by the method comprising: The mass ratio of the ZIF-Co powder to the nickel acetylacetonate is 4:1-16:

1.

4. The method of claim 2, wherein the highly reconstructed Ni-doped glassy MOFs electrocatalyst is prepared by the method comprising: The molar ratio of imidazole to benzimidazole is 5:1-8:1; the molar ratio of the organic ligand to the cobalt salt is 2:1-4:1; and the mass ratio of the cobalt salt to the solvent is 1:60-1:

120.

5. The method of claim 1, wherein the highly reconstituted Ni-doped glassy MOFs electrocatalyst is prepared by the steps of: The hydrothermal reaction is performed at a temperature of 120-150℃ for 48-168h.

6. The method of claim 1, wherein the highly reconstructed, Ni-doped glassy MOFs electrocatalyst is prepared by the method comprising: The powder precursor is loaded on the electrode material to obtain an electrode material loaded with a catalyst, comprising the following steps: The electrode material is placed on the inner wall of a ball mill jar, and the powder precursor is added and subjected to ball milling to obtain an electrode material loaded with a catalyst. 7.A highly restructured Ni-doped glassy MOFs electrocatalyst prepared by the method according to any one of claims 1-6. 8.Use of a highly restructured Ni-doped glassy MOFs electrocatalyst prepared by the method according to any one of claims 1-6 in electro-oxidation of 5-hydroxymethylfurfural.

Images