A catalyst, its preparation method, and the application of the anode prepared as an anode material in the electrocatalytic oxidation of glycerol to formate.

Abstract

This application discloses a catalyst and its preparation method, as well as the application of an anode prepared as an anode material in the electrocatalytic oxidation of glycerol to formate. The catalyst comprises a matrix and an alloy supported on the surface of the matrix; the alloy is selected from at least four of the metallic elements Co, Ni, Cu, Mn, Mo, Fe, W, and Cr; each metallic element accounts for 5% to 35% of the total metallic elements in the alloy; the amount of the alloy supported on the matrix surface is 1 to 1.3 mg / cm³. 2 The matrix is ​​selected from carbon cloth, titanium mesh, titanium sheet, and nickel foam. The catalyst described in this application is a high-entropy alloy. Its electron transfer ability as a catalyst in redox reactions has broad application prospects. It is environmentally friendly, low-cost, highly stable, uses simple raw materials, and exhibits high catalytic activity. The preparation method is simple, and the equipment is basic.

Description

Technical Field

[0001] This invention relates to a catalyst and its preparation method, and the application of an anode prepared as an anode material in the electrocatalytic oxidation of glycerol to formate, belonging to the fields of inorganic catalyst material synthesis and electrochemical synthesis. Background Technology

[0002] Hydrogen is widely considered one of the most promising energy carriers, possessing advantages such as high energy density, abundant sources, cleanliness, and sustainable development. Water electrolysis has long been considered a clean hydrogen production technology, but this has been hampered by some drawbacks of oxygen evolution reaction (OER) at the anode, such as slow kinetics, formation of reactive oxygen species, and low oxygen cost. The electrochemical oxidation of some organic compounds, such as methanol, glycerol, 5-hydroxymethylfurfural (HMF), and primary amines, provides a favorable alternative to OER at the anode, not only improving the energy efficiency of water electrolysis but also yielding value-added chemicals. Among these studied organic molecules, glycerol is a low-cost byproduct in the biodiesel production industry. Furthermore, the electrochemical oxidation of glycerol has a very low theoretical oxidation potential (0.003 V), and its oxidation products (glyceric acid, dihydroxyacetone, glycolic acid, formic acid, etc.) have promising broad application prospects. Therefore, the catalytic oxidation of glycerol (GOR) is an ideal alternative to OER. Due to the favorable kinetics of GOR and the diversity of glycerol oxidation products, electrocatalysts play a crucial role in GOR. Noble metal-based materials have been extensively explored as electrocatalysts for GOR (Gas-Organic Regenerative Catalysis), but their high cost and limited Earth reserves hinder their practical application. Although some noble metal-free transition metal compounds have been reported for GOR, few catalysts have achieved both good activity and selectivity. Therefore, efforts remain to develop highly efficient electrocatalysts for GOR.

[0003] High entropy alloys (HEAs) are crystalline solid solutions composed of five or more elements, attracting widespread attention due to their superior physicochemical properties. Besides excellent hardness and toughness, corrosion resistance, and thermal stability, the random distribution of multiple elements in a single phase in HEAs endows them with inherent synergistic effects, severe lattice distortion, and flexible tunability of elemental concentration and electronic structure. This provides abundant active sites, making them promising for applications in energy storage and conversion. In the field of electrocatalysis, high entropy alloys exhibit excellent electrocatalytic performance in CO oxidation, carbon dioxide reduction, oxygen reduction, oxygen evolution reaction, hydrogen evolution reaction, and nitrogen reduction. However, the application of HEA catalysts in GOR (Gas Oxidation Reduction) has not yet received sufficient attention. Given the diverse types and unique structures of HEA materials, there is significant potential for developing novel GOR electrocatalysts with high selectivity and activity. Summary of the Invention

[0004] This invention provides a catalyst supported on CoNiCuMnMo high-entropy alloy nanoparticles, its preparation method, and its application. The CoNiCuMnMo high-entropy alloy nanoparticles supported on the substrate are densely and uniformly distributed, with controllable loading, uniform nanoparticle size, and small particle size. The carbon cloth substrate improves the conductivity, thereby significantly enhancing the catalytic oxidation performance of glycerol.

[0005] According to one aspect of this application, a catalyst is provided, the catalyst comprising a matrix and an active component supported on the surface of the matrix;

[0006] The active component comprises a metal element alloy; the metal element alloy contains at least four selected from Co, Ni, Cu, Mn, Mo, Fe, W, and Cr.

[0007] The percentage of each metal element in the active component is 5% to 35% of the total amount of metal elements in the active component.

[0008] The amount of the active component loaded on the substrate surface is 1–1.3 mg / cm³. 2 .

[0009] The matrix is ​​selected from at least one of carbon cloth, titanium mesh, titanium sheet, and nickel foam;

[0010] The amount of the active component loaded on the substrate surface is 1.1 mg / cm³. 2 ;

[0011] The metal element alloy has a face-centered cubic nanoparticle structure; the diameter of the face-centered cubic nanoparticle structure is 5-20 nm.

[0012] According to another aspect of this application, a method for preparing the above-mentioned catalyst is provided, comprising the following steps: mixing a raw material containing an active component precursor with an organic solvent, an organic acid, and an aqueous ethanol solution to obtain a mixed solution; immersing the matrix in the mixed solution to undergo a solvothermal reaction to obtain the catalyst.

[0013] The molar ratio of the active component precursor to the volume ratio of the organic solvent is 2-3 mmol: 20-30 ml;

[0014] The molar ratio of the organic acid to the volume ratio of the organic solvent is 10–15 mmol: 20–30 ml.

[0015] The volume ratio of the ethanol-water solution to the organic solvent is 2-4 ml : 20-30 ml.

[0016] The active component precursor is selected from at least one of the chloride, nitrate, and acetate salts of the metal element;

[0017] The organic solvent is selected from at least one of N,N-dimethylformamide, N-methylpyrrolidone, dimethylacetamide, and 1,3-dimethyl-2-imidazolinone;

[0018] The organic acid is selected from at least one of 2,5-dihydroxyterephthalic acid, 1,4-phthalic acid, and trimesic acid.

[0019] The main role of organic acids is to act as organic ligands to form high-entropy organometallic frameworks (HE-MOFs) with various metal ions. On the other hand, they interact with hydroxyl groups on the treated matrix, which is beneficial for the uniform in-situ growth of HE-MOFs on the matrix surface.

[0020] The ethanol-water solution has an ethanol volume concentration of 50%.

[0021] The temperature of the solvothermal reaction is 120–140°C, and the time of the solvothermal reaction is 24–36 h.

[0022] The catalyst is also calcined in a mixed atmosphere of hydrogen and inactive gas.

[0023] In the mixed atmosphere, the volume percentage of hydrogen is 5-10%;

[0024] The inactive gas is selected from nitrogen or an inert gas;

[0025] The roasting temperature is 350℃~1200℃; the roasting time is 3.5~4h;

[0026] Optionally, when the alloy does not contain W and Cr elements, the calcination process includes: holding at 350°C for 1 hour, and then calcining at 450-500°C for 2-3 hours.

[0027] Optionally, when the alloy contains W, the calcination process includes: holding at 350°C for 1 hour, and then calcining at 650-750°C for 2-3 hours.

[0028] Optionally, when the alloy contains Cr, the calcination process includes: first holding at 450°C for 1 hour, then raising the temperature to 1000-1200°C and calcining for 2-3 hours.

[0029] The matrix undergoes pretreatment;

[0030] The pretreatment process includes pretreatment of the hydrophilic carbon cloth substrate by boiling it in 0.5M H2SO4 and 30% H2O2 at 80°C for 1 hour, followed by washing with deionized water and drying.

[0031] The titanium mesh was ultrasonically cleaned for 3 minutes each with anhydrous ethanol, 0.05-0.2 mol / L dilute hydrochloric acid, and pure water, then rinsed with deionized water and dried.

[0032] The titanium sheet was ultrasonically cleaned for 3 minutes each with anhydrous ethanol, dilute hydrochloric acid with a mass fraction of 0.05-0.2 mol / L, and pure water, then rinsed with deionized water and dried.

[0033] The nickel foam was ultrasonically cleaned for 3 minutes each with anhydrous ethanol, dilute hydrochloric acid with a mass fraction of 0.05-0.2 mol / L, and pure water, then rinsed with deionized water and dried.

[0034] The matrix is ​​cleaned and dried before calcination;

[0035] The cleaning and drying process includes rinsing with deionized water and anhydrous ethanol 3 to 5 times, followed by vacuum drying at 60°C for 24 hours.

[0036] When the substrate is carbon cloth, the size and area of ​​the carbon cloth are 1-2 cm × 1-2 cm.

[0037] Furthermore, the carbon cloth has a size of 2cm × 2cm.

[0038] According to another aspect of this application, an anode material is provided, the anode material comprising the catalyst described above or the catalyst prepared by the preparation method described above.

[0039] According to another aspect of this application, an electrocatalytic anode is provided, the anode comprising the aforementioned anode material.

[0040] According to another aspect of this application, the above-described electrocatalytic anode is provided for use in the electrocatalytic oxidation of glycerol to formate, wherein the electrocatalytic anode achieves 10 mA / cm² in 1.0 mol / L KOH containing 0.1 mol / L glycerol. 2 The voltage; in the range of 1.29–1.45V, the Tafel slope is 96.0–120.0 mV dec. -1 The driving potential when using the RHE (reversible hydrogen electrode) as a reference electrode is not less than 1.20V.

[0041] The beneficial effects that this application may produce include at least the following:

[0042] 1) The catalyst described in this application is a high-entropy alloy. Due to the high-entropy effect, cocktail effect, hysteresis and diffusion effect and lattice distortion effect of high-entropy alloy, the high mixing entropy promotes the free and disordered distribution of each component element, which is conducive to the formation of a simple solid solution. Moreover, the multiple metal element components tend to be arranged randomly. The multi-element alloy induces the formation of a single solid solution through high entropy, so that the metal element components are evenly distributed, resulting in the formation of a large number of new active centers. This improves the electron transfer ability of the supported CoNiCuMnMo high-entropy alloy nanoparticle catalyst as a catalyst in redox reactions, and has broad application prospects.

[0043] 2) The preparation equipment for preparing nanoparticle catalysts supported on CoNiCuMnMo high-entropy alloys by solvothermal growth and hydrogen reduction calcination pyrolysis is simple and easy to operate.

[0044] 3) The material prepared by this invention is an environmentally friendly material with low cost, high stability, and simple raw material selection, which can be used for large-scale industrial production.

[0045] 4) Electro-oxidation of glycerol to formate using nanoparticle catalysts supported on CoNiCuMnMo high-entropy alloys achieved 10 mA / cm². -2 The potential of the current density does not exceed 1.29V vs. RHE, and is within 10mA cm⁻¹. -2 Constant current electrolysis at a current density for 12 hours resulted in a Faraday efficiency of over 90% for formate. Attached Figure Description

[0046] Figure 1 The XRD diffraction pattern of the precursor HE-MOF obtained in Example 1 (4) is shown.

[0047] Figure 2a The image shows the XRD diffraction pattern of the catalyst material prepared in Example 1.

[0048] Figure 2b The image shows the XRD diffraction pattern of the high-entropy alloy nanoparticles obtained in Example 2.

[0049] Figure 2c It is an XRD standard card with an FCC structure for Cu.

[0050] Figure 3 a is a scanning electron microscope image of the catalyst material prepared in Example 1 at the 2μm scale.

[0051] Figure 3 b is a scanning electron microscope image of the catalyst material prepared in Example 1 at the 100 nm scale.

[0052] Figure 4 Transmission electron microscopy image of the catalyst material prepared in Example 1

[0053] Figure 5 The polarization curve is a performance test diagram of an anode prepared using the catalyst material obtained in Example 1 for catalytic glycerol oxidation.

[0054] Figure 6 The nuclear magnetic resonance spectrum of the nanoparticle catalyst supported on CoNiCuMnMo high-entropy alloy used in Test Example 5 of this application for the analysis of glycerol oxidation products. Detailed Implementation

[0055] The present application is described in detail below with reference to the embodiments, but the present application is not limited to these embodiments.

[0056] Unless otherwise specified, the raw materials and reagents used in the embodiments of this application were purchased commercially, and the hydrophilic carbon cloth was purchased from Haote New Materials Co., Ltd.

[0057] The analysis method in the embodiments of this application is as follows:

[0058] XRD diffraction of the samples was performed using a Miniflex 6000 at 40 kV and 15 mA with Cu-Kα radiation. Characterization was performed at a scanning speed of 10° / min.

[0059] The samples were characterized by scanning electron microscopy (SEM) using a JSM6700-F field emission scanning electron microscope; and by transmission electron microscopy (TEM) using a TECNAI G2 F20 field emission scanning electron microscope.

[0060] Cyclic voltammetry of the electrodes was performed on a CHI760E electrochemical workstation from Shanghai Chenhua Co., Ltd.

[0061] Sample product analysis was performed using an EC-600R nuclear magnetic resonance instrument.

[0062] Example 1: Preparation of nanoparticle catalysts supported on high-entropy alloy CoNiCuMnMo grown in situ on carbon cloth

[0063] (1) Cut the commercial carbon cloth to the required size (2cm×2cm), boil it in 0.5MH2SO4 and 30%H2O2 at 80℃ for 1 hour, wash it with deionized water and dry it for later use.

[0064] (2) Weigh out equimolar amounts of 0.5 mmol each of CoCl2·6H2O, NiCl2·6H2O, CuCl2·2H2O, MnCl2·5H2O, and MoCl3, and 2.5 g of 2,5-dihydroxyterephthalic acid. Then add 26 ml of DMF, 2 ml of anhydrous ethanol, and 2 ml of ultrapure water, and dissolve by sonication to obtain a mixed solution.

[0065] (3) Transfer the mixed solution obtained in step (2) into a 50ml reactor liner, and immerse the carbon cloth treated in step (1) into the bottom of the liner, completely submerging it in the mixed solution. Place it in the stainless steel sleeve of the reactor and put it in an oven at 120℃ for 24h.

[0066] (4) Take out the carbon cloth from step (3), rinse it several times with anhydrous ethanol and ultrapure water respectively, and put it into a vacuum drying oven to dry at 60°C to obtain the precursor HE-MOF loaded on the carbon cloth.

[0067] (5) The carbon cloth treated in step (4) is placed in a ceramic boat and placed in the middle of a tube furnace. Under a mixed protective reducing atmosphere of 90% argon and 10% hydrogen, the temperature is first raised from room temperature to 350°C at a rate of 5°C / min, and held at 350°C for 1 hour. Then, the temperature is raised from room temperature to 500°C at a rate of 5°C / min, and held at 500°C for 2 hours. Then, the temperature is naturally cooled to room temperature to obtain nanoparticle catalysts of CoNiCuMnMo high-entropy alloy grown in situ on hydrophilic carbon cloth.

[0068] Figure 1 The XRD diffraction pattern of the precursor HE-MOF obtained in (4) shows that the precursor HE-MOF has a MOF structure.

[0069] Example 2: Preparation of nanoparticles of CoNiCuMnMo high-entropy alloy

[0070] High-entropy alloy nanoparticles of CoNiCuMnMo were prepared using the same method as in Example 1, but without the addition of carbon cloth.

[0071] Test Example 1: XRD Characterization of Nanoparticle Catalysts Supported with CoNiCuMnMo High-Entropy Alloy

[0072] The samples obtained in Examples 1 and 2 were characterized using a Miniflex 6000 instrument.

[0073] Figure 2a The image shows the XRD diffraction pattern of the catalyst material prepared in Example 1. Figure 2b The XRD diffraction pattern is shown for the catalyst material obtained using the same method as in Example 1 without the addition of carbon cloth. Figure 2c It is an XRD standard card with an FCC structure for Cu.

[0074] Will Figure 2a and Figure 2b Compared with the standard card, it can be seen that... Figure 2a The sample shows a single FCC structure. Figure 2b It also uses a single FCC structure.

[0075] Test Example 2: SEM Characterization of Nanoparticle Catalysts Supported with CoNiCuMnMo High-Entropy Alloy

[0076] The fine morphology of the samples obtained in Examples 1 and 2 was examined using scanning electron microscopy (SEM), and the SEM images are shown below. Figure 3 As shown. Figure 3 a is a scanning electron microscope image of the catalyst material prepared in Example 1 at a 2 μm scale; Figure 3 b is a scanning electron microscope image of the catalyst material prepared in Example 1 at the 100 nm scale.

[0077] Figure 3 a shows that the sample is uniformly and evenly loaded on the hydrophilic carbon cloth. Figure 3 As can be seen from b, the material consists of densely packed spherical nanoparticles with a diameter of approximately 10 nm.

[0078] Test Example 3: TEM characterization of nanoparticle catalysts supported on CoNiCuMnMo high-entropy alloys

[0079] The morphology of the samples obtained in Examples 1 and 2 was examined in more detail using transmission electron microscopy (TEM). The TEM images are shown below. Figure 4 As shown. Figure 4 The sample appears to be composed of uniform spherical nanoparticles (dashed circle), with a particle diameter of approximately 10 nm, consistent with SEM results. The nanosized high-entropy alloy particles increase the contact area with the electrolyte, providing abundant active sites for the electrocatalytic process.

[0080] Test Example 4: The hydrophilic carbon cloth containing the in-situ grown CoNiCuMnMo high-entropy alloy nanoparticle catalyst from Example 1 was used as the anode electrode (A#) for the electrochemical testing of GOR.

[0081] The hydrophilic carbon cloth electrode sheet with CoNiCuMnMo high-entropy alloy nanoparticle catalyst grown in situ in Example 1 was subjected to linear sweep spectroscopy (LSV) testing on an electrochemical workstation. The electrolytes were as follows:

[0082] 1) The electrolyte consisted of 1.0 mol / L KOH and 0.1 mol / L glycerol. The catalytic oxidation of glycerol (GOR) was tested.

[0083] 2) The electrolyte is 1.0 mol / L KOH, and the oxygen evolution reaction (OER) performance is tested.

[0084] The linear scan curves of electrode A# in the two electrolytes mentioned above are as follows: Figure 5As shown in the figure, the OER reaction occurring on the anolyte surface in 1.0 mol / L KOH is followed by the GOR reaction after the addition of 0.1 mol / L glycerol solution. The corresponding oxidation current increases rapidly near 1.20 V vs. RHE, reaching 10 mA cm⁻¹. -2 The required potential is 1.29V vs. RHE.

[0085] The results showed that carbon cloth with in-situ grown CoNiCuMnMo high-entropy alloy nanoparticle catalyst as an anode electrode exhibited good GOR catalytic performance.

[0086] Test Example 5: Qualitative and quantitative analysis of anolyte products after long-term constant current electrolysis of A# anolyte electrode.

[0087] Nuclear magnetic resonance (NMR) technology was used to analyze the anolyte products, such as... Figure 6 As shown, qualitative and quantitative analysis by liquid chromatography-nuclear magnetic resonance (LC-NMR) revealed that the substance produced by anodic electro-oxidation of glycerol is formate. This was achieved using a current density of 10 mA cm⁻¹. -2 Constant current electrolysis was performed, followed by qualitative and quantitative analysis using liquid-phase NMR. Calculations showed that the Faraday efficiency for formate production exceeded 90%.

[0088] The above description is merely a few embodiments of this application and is not intended to limit this application in any way. Although this application discloses preferred embodiments as described above, it is not intended to limit this application. Any changes or modifications made by those skilled in the art without departing from the scope of the technical solution of this application using the disclosed technical content are equivalent to equivalent implementation cases and fall within the scope of the technical solution.

Claims

1. The application of an electrocatalytic anode in the electrocatalytic oxidation of glycerol to formate, characterized in that, The electrocatalytic anode, in 1.0 mol / L KOH containing 0.1 mol / L glycerol, achieves 10 mA / cm². 2 The potential at the current density relative to the standard hydrogen electrode does not exceed 1.29 V; in the range of 1.29–1.45 V, the Tafel slope is 96.0–120.0 mV dec. -1 ; The electrocatalytic anode contains an anode material; The anode material includes a catalyst; The catalyst comprises a matrix and an active component supported on the surface of the matrix; The active component comprises a metallic element alloy; the metallic element in the metallic element alloy is selected from Co, Ni, Cu, Mn, and Mo; The percentage of each metal element in the active component is 5% to 35% of the total metal elements in the active component. The amount of the active component loaded on the substrate surface is 1~1.3 mg / cm³. 2 .

2. The application according to claim 1, characterized in that, The matrix is ​​selected from at least one of carbon cloth, titanium mesh, titanium sheet, and nickel foam; The amount of the active component loaded on the substrate surface is 1.1 mg / cm³. 2 ; The metallic alloy has a face-centered cubic nanoparticle structure; the diameter of the face-centered cubic nanoparticle structure is 5~20 nm.

3. The application according to claim 1, characterized in that, The method for preparing the catalyst includes the following steps: mixing a raw material containing an active component precursor with an organic solvent, an organic acid, and an aqueous ethanol solution to obtain a mixed solution; immersing the matrix in the mixed solution to undergo a solvothermal reaction to obtain the catalyst; The active component precursor is selected from at least one of the chloride, nitrate, and acetate salts of the metal element; The organic solvent is selected from at least one of N,N-dimethylformamide, N-methylpyrrolidone, dimethylacetamide, and 1,3-dimethyl-2-imidazolinone; The organic acid is selected from at least one of 2,5-dihydroxyterephthalic acid, 1,4-phthalic acid, and trimesic acid. The volume concentration of ethanol in the aqueous ethanol solution is 50%. The catalyst is also calcined in a mixed atmosphere of hydrogen and inactive gas. In the mixed atmosphere, the volume percentage of hydrogen is 5-10%; The roasting temperature is 350℃~1200℃; the roasting time is 3.5~4h; The roasting process includes: holding at 350℃ for 1 hour, then raising the temperature to 450~500℃ and roasting for 2~3 hours.

4. The application according to claim 3, characterized in that, The molar ratio of the active component precursor to the volume ratio of the organic solvent is 2-3 mmol: 20-30 ml; The molar ratio of the organic acid to the volume ratio of the organic solvent is 10~15 mmol: 20~30 ml; The volume ratio of the ethanol-water solution to the organic solvent is 2-4 ml : 20-30 ml.

5. The application according to claim 3, characterized in that, The temperature of the solvothermal reaction is 120~140℃, and the time of the solvothermal reaction is 24~36h.

6. The application according to claim 3, characterized in that, The inactive gas is selected from inert gases.

7. The application according to claim 3, characterized in that, The inactive gas is selected from nitrogen.

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