Difunctional superfine high-entropy nano-catalyst for ethylene glycol electrochemical oxidation coupling electrolytic hydrogen production and preparation method of difunctional superfine high-entropy nano-catalyst

Abstract

The invention discloses a bifunctional superfine high-entropy nano-catalyst for ethylene glycol electrochemical oxidation coupling electrolytic hydrogen production and a preparation method thereof. The manufacturing method is simple and convenient, the high-entropy nano-structure alloy is synthesized only through a solvothermal method, and carbon black is loaded; the temperature of the whole synthesis process is lower than 200 DEG C, no solvent needs to be added, and the problems of high cost, high energy consumption, poor stability, large potential safety hazards and the like in a traditional synthesis method are solved. The high-entropy nano-catalyst prepared by the invention shows excellent performance in electro-catalysis ethylene glycol oxidation and electro-catalysis hydrogen evolution reaction. In a membrane-free flowing electrolytic tank assembled by using the catalyst as a bifunctional catalyst, the effect of industrial-grade co-production of hydrogen and glycollic acid can be realized only by using the voltage of 0.724 V, and the catalyst can stably run for more than 1200 hours. Crude ethylene glycol derived from waste PET plastics also shows an industrial-grade effect in an outdoor electrolysis process in which a photovoltaic panel is driven by solar energy to generate electricity.

Description

Technical Field

[0001] The invention belongs to the technical field of electrocatalyst preparation, and specifically relates to an ultrafine high-entropy nanocatalyst for ethylene glycol electrochemical oxidation coupled electrolysis to produce hydrogen and a preparation method thereof. Background Art

[0002] Polyethylene terephthalate (PET) is a widely used plastic with an annual consumption of more than 70 million tons. It is a copolymer synthesized by the esterification reaction of terephthalic acid and ethylene glycol - ethylene glycol (EG). The traditional treatment methods for waste PET are landfill and mechanical treatment. Since there is no known biomass that can decompose PET, it is difficult to completely solve this large amount of waste PET by landfill, and the performance of waste PET treated by mechanical method is much worse than before. With the generation of more and more waste PET, the environmental impact is becoming more and more serious, and it has threatened the life safety of terrestrial and aquatic organisms. Alkaline hydrolysis can quickly depolymerize PET into EG and terephthalate monomers under mild conditions. By adjusting the acidity of the hydrolyzate, terephthalate can form slightly soluble terephthalic acid for separation. However, EG has low volatility, high viscosity, and good water solubility, making it difficult to separate and purify. Therefore, how to effectively utilize crude EG is a key issue in the chemical cycle of waste PET plastics.

[0003] Driven by sustainable energy, the crude EG in the above-mentioned chemical cycle of waste PET plastics is used as raw material, bypassing the separation and purification steps, and directly electrochemically oxidizing it into chemicals with higher added value (such as glycolic acid GA) and coupling it with electrochemical hydrogen evolution reaction. This strategy is expected to solve the problems of purification difficulties in the chemical cycle of waste PET plastics, and can also achieve efficient, low-energy, and low-carbon symbiosis of high-value-added chemicals and hydrogen.

[0004] In past studies, Pt group metal catalysts were considered to be electrocatalysts that can efficiently catalyze EG oxidation and hydrogen evolution reactions. This is mainly because Pt group metals have a specific electronic structure and can efficiently adsorb reactants, thus showing strong competitiveness in EG electrooxidation and hydrogen evolution reactions. Although Pt group metal resources are scarce and expensive, this shortcoming can be overcome by introducing non-precious metals and long-term stable and efficient catalysis. However, in the catalytic process of Pt-based catalysts, due to the strong adsorption of Pt group metals with substrates, some reaction intermediates such as some carbonyl compounds will also be "stubbornly" adsorbed on the catalytic sites, causing catalyst "poisoning". Therefore, when designing efficient and highly stable Pt group metal catalysts, it is necessary to appropriately reduce the adsorption of carbonyl-containing intermediates by the catalytic center and remove "toxic species" in time. However, reducing the effect of Pt-based catalytic sites on carbon-based compounds may also weaken the adsorption of catalytic sites and reactants. Therefore, it is necessary to find a "balance point" between the two, which makes the design and synthesis of Pt group metal catalysts challenging.

[0005] To solve this problem, some researchers have tried to optimize the electronic structure of the catalytic site by doping a small amount of Ir. Through this adjustment, the toxic intermediates adsorbed near Ir can be effectively removed, thereby "liberating" more catalytic sites, thereby achieving improved activity and stability of ethylene glycol oxidation. Although the above strategy has improved the stability of EGOR to a certain extent, it still cannot meet the requirements of large-scale commercial applications.

[0006] Recently, high entropy alloy materials have attracted widespread attention from researchers due to their huge structural regulation space, high thermal stability, unique crystal structure and other advantages. Existing literature reports a catalyst for preparing a high-entropy PdPtCuAgAu nanowire network using a carboxyl-functionalized surfactant as a soft template (Dongping Fan, Ke Guo, Yan Zhang, et al. Engineering high-entropy alloy nanowires network for alcohol electrooxidation. Journal of Colloid and Interface Science, 625, 2022, 1012-1021). Compared with other nanoparticle catalysts, this catalyst has outstanding advantages in synergistic composition (such as high entropy effect, slow diffusion effect and lattice distortion effect) and structure (anisotropy and thin nanowires), but its stability is poor and it is difficult to apply industrially. Existing literature reports a trimetallic palladium-silver-copper nanosheet assembly nanocatalyst (Li, Z., Lao, X., Yang, L. et al. Assembly of trimetallic palladium-silver-copper nanosheets forefficient C 2 alcohol electrooxidation. Sci. China Mater. 66, 150-159 (2023).), compared with other nanoparticle catalysts, this catalyst has the advantage of excellent long-term stability, but due to its large nanoparticle size, fewer exposed active sites, and low utilization of precious metal atoms, the catalyst activity is poor and difficult to apply industrially. In addition, most of the reported high-entropy alloys are synthesized under high temperature conditions, which consumes a lot of energy and has high cost (Yao, Yonggang, et al. "High-entropy nanoparticles: Synthesis-structure-property relationships and data-driven discovery." Science 376. 6589 (2022): eabn3103.;). Summary of the invention

[0007] The present invention aims to develop a new bifunctional ultrafine high entropy nanocatalyst with high activity and strong stability in electrocatalytic oxidation of crude ethylene glycol coupled with electrolysis to produce hydrogen. By mixing a metal source with a reducing agent, iridium-doped palladium, platinum, gold, nickel, and copper high entropy ultrafine nanoparticles (Ir-PdPtAuNiCu HEANs) are synthesized under the protection of a surfactant, and carbon black is added and uniformly dispersed to obtain carbon black-loaded iridium-doped palladium, platinum, gold, nickel, and copper high entropy ultrafine nanoparticles (Ir-PdPtAuNiCu HEANs-C) for efficient and stable catalysis of ethylene glycol electrooxidation reactions, so as to solve the problems of high manufacturing cost, high energy consumption, low activity, and poor stability of traditional Pt-based catalysts. Interestingly, if no iridium (Ir) metal source is added during the synthesis process, PdPtAuNiCu HEANs-C with better hydrogen evolution reaction performance than commercial catalysts can be obtained. In a membraneless, flowing electrolytic cell with Ir-PdPtAuNiCuHEANs-C as the anode ethylene glycol oxidation reaction catalyst and PdPtAuNiCu HEANs-C as the cathode hydrogen evolution reaction catalyst, crude ethylene glycol was used as the substrate to achieve efficient and stable symbiosis of glycolic acid and hydrogen.

[0008] In order to achieve the above object, the technical solution of the present invention is as follows:

[0009] The present invention provides a method for preparing ultrafine high entropy nanoparticles for a catalyst of a crude ethylene glycol electrochemical oxidation coupled hydrogen production electrolysis cell, comprising the following steps:

[0010] (1) Mixing and dispersing a metal source, a reducing agent and a surfactant, and synthesizing ultrafine high entropy nanomaterials by a solvothermal method at a temperature below 200° C. under the protection of an inert atmosphere;

[0011] The metal source contains a copper source, a platinum source, a nickel source, a palladium source and a gold source;

[0012] (2) The high entropy ultrafine nanomaterial obtained in step (1) is mixed and dispersed with a carbon material to obtain the ultrafine high entropy nanocatalyst.

[0013] As a preferred embodiment, in step (1), the metal source further comprises an iridium source;

[0014] The copper source, platinum source and iridium source are copper acetylacetonate, platinum acetylacetonate and iridium acetylacetonate respectively.

[0015] The nickel source is nickel chloride or nickel acetylacetonate,

[0016] The palladium source is palladium chloride or palladium acetylacetonate,

[0017] The gold source is chloroauric acid;

[0018] The reducing agent is ascorbic acid,

[0019] The surfactant is oleylamine.

[0020] Further preferably, the molar mass ratio of copper element: nickel element: palladium element: platinum element: iridium element: gold element in the metal source is 1:1:1:1:1:1:1 or 3:2:3:3:3:3.

[0021] Preferably, in step (1), the solvent thermal method is as follows: first react at a reaction temperature of 170° C. for 2 h, then raise the reaction temperature to 200° C., and react at 200° C. for 1 h. The heating rate is 6° C. / min. The present invention has low energy consumption, and the temperature during the entire preparation process is not higher than 200° C.

[0022] As a preferred embodiment, in step (1), after heating the reaction, washing with an organic solvent is performed;

[0023] The organic solvent is a mixed solution of cyclohexane and anhydrous ethanol, and the volume ratio of the cyclohexane to the anhydrous ethanol is 7:1.

[0024] As a preferred embodiment, in step (2), the carbon material is carbon black; and the mass ratio of the carbon material to the ultrafine high entropy nanomaterial is 2:1-3.

[0025] The invention provides a preparation method for preparing a carbon-supported ultrafine high-entropy nanoparticle catalyst.

[0026] The carbon-supported high-entropy ultrafine nanocatalyst (Ir-PdPtAuNiCu HEANs-C and PdPtAuNiCuHEANs-C) is composed of palladium, platinum, iridium, gold, nickel, copper nanoparticles with a particle size ranging from 3 to 7 nm and palladium, platinum, gold, nickel, copper and carbon black, respectively, with an average particle size of 5.45±0.05 nm.

[0027] The present invention also provides the use of the two ultrafine high entropy nanocatalysts in an efficient and stable electrocatalytic ethylene glycol oxidation coupled hydrogen production electrolysis cell.

[0028] In particular, it is used for the efficient and high stability catalytic electro-oxidation of crude ethylene glycol from waste PET plastics coupled with hydrogen production electrolysis.

[0029] Compared with the prior art, the present invention has the following beneficial effects:

[0030] (1) The preparation method of the present invention is simple and convenient. It only needs to synthesize ultrafine high entropy nanostructures (Ir-PdPtAuNiCu HEANs and PdPtAuNiCu HEANs) by a low-temperature solvothermal method and load carbon black. The synthesis process is safe and green, avoiding the problems of high cost, high energy consumption, poor stability, and great safety hazards existing in traditional synthesis methods.

[0031] (2) The temperature of the present invention during the whole manufacturing process is not higher than 200°C, which has low energy consumption, high safety and low cost. Non-precious metal materials are used in the manufacturing process, which can further reduce the production cost.

[0032] (3) The ultrafine high-entropy nanocatalyst prepared by the present invention is a nanoparticle with regular morphology and uniform size (average diameter of 5.5 nm) and a relatively obvious high-entropy alloy structure.

[0033] (4) The Ir-PdPtAuNiCu HEANs-C and PdPtAuNiCu HEANs-C prepared by the present invention exhibit excellent ethylene glycol oxidation and hydrogen evolution catalytic performance, respectively. In a membraneless, flowing electrolytic cell in which these two materials are ethylene glycol electro-oxidation and hydrogen evolution catalysts, respectively, they exhibit efficient and stable application effects in the resource application of crude ethylene glycol from waste PET plastics and hydrogen production.

[0034] (5) The ultrafine high entropy nanocatalyst prepared by the present invention has several significant features: ① The structure is a high entropy alloy; ② The morphology is ultrafine nanoparticles of uniform size; ③ The synthesis method does not exceed 200°C, with low energy consumption and low cost; ④ The Ir-PdPtAuNiCu HEANs-C and PdPtAuNiCu HEANs-C materials synthesized by this method can be used as bifunctional electrocatalysts to efficiently and stably catalyze the electro-oxidation reaction of ethylene glycol and the hydrogen evolution reaction. In the catalytic electro-oxidation reaction of ethylene glycol, the activities of Ir-PdPtAuNiCuHEANs-C and PdPtAuNiCu HEANs-C catalysts far exceed those of commercial Pt / C catalysts, among which Ir-PdPtAuNiCuHEANs-C has the best performance; after 1000 cycles of CV cycle test, the catalytic activity of Ir-PdPtAuNiCu HEANs-C only decreased by 0.6%. At the same time, when catalyzing the hydrogen evolution reaction, the activity of Ir-PdPtAuNiCu HEANs-C and PdPtAuNiCu HEANs-C catalysts also far exceeds that of commercial Pt / C catalysts, among which PdPtAuNiCu HEANs-C has the best performance. In a membraneless, flowing electrolytic cell with the above-mentioned optimal materials as cathode and anode catalysts, only a voltage of 0.724V is required to achieve the effect of industrial-grade co-production of hydrogen and glycolic acid. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] Figure 1 It is the TEM characterization spectrum and elemental analysis of the high entropy nanocatalyst described in Example 1 of the present invention; wherein, a is the TEM image; b is the size distribution; c is the HR-TEM image and the corresponding d is the lattice spacing; e is the EDS line scan; f is the element surface scan; g is the chemical composition determined by EDS, XPS and ICP-MS.

[0036] Figure 2 It is the TEM characterization spectrum and elemental analysis of the high entropy nanocatalyst described in Example 2 of the present invention; wherein, a is the TEM image; b is the size distribution; c is the HR-TEM image and the corresponding d is the lattice spacing; e is the EDS line scan; f is the element surface scan; g is the chemical composition determined by EDS, XPS and icp-ms.

[0037] Figure 3 It is the XRD diagram of the high entropy nanocatalyst described in Examples 1-2 of the present invention and Comparative Example 1.

[0038] Figure 4 This is the LSV test diagram of Example 1 of the present invention in NaOH solution and ethylene glycol + NaOH solution.

[0039] Figure 5 The LSV test graphs of Example 1 and Example 2 of the present invention in ethylene glycol small molecules are compared with the performance of commercial Pd / C and Pt / C.

[0040] Figure 6 It is the LSV test graph of Example 1 of the present invention and Comparative Examples 2 and 3 in ethylene glycol small molecules.

[0041] Figure 7 It is the LSV test graph of Example 1 of the present invention and Comparative Examples 4, 5, and 6 in ethylene glycol small molecules.

[0042] Figure 8 The three-electrode IT test diagram of Example 1 and Example 2 of the present invention in ethylene glycol solution is compared with the performance of commercial Pd / C and Pt / C.

[0043] Fig. 9 The LSV graphs of the products prepared in Example 1 and Example 2 of the present invention before and after 1000 cycles of cyclic voltammetry test in ethylene glycol solution after being assembled into electrodes.

[0044] Fig.10 The products prepared in Example 1 and Example 2 of the present invention were assembled into electrodes and subjected to IT tests at different potentials in ethylene glycol solutions. The products were collected and the Faraday efficiency of the products was calculated by NMR analysis.

[0045] Fig.11 The products prepared in Example 1 and Example 2 of the present invention were assembled into electrodes and subjected to IT testing at the same potential in ethylene glycol solution for different periods of time. The products were collected and the Faraday efficiency of the products was calculated by NMR analysis.

[0046] Fig.12 The LSV test diagrams of Example 1 and Example 2 of the present invention in NaOH solution are compared with the performance of commercial Pt / C.

[0047] Fig.13 Graph showing the relationship between current density and electrolysis time for assembling the [(-)PdPtAuNiCu| |Ir-PdPtAuNiCu(+)] membrane-free flow electrolytic cell in Example 1 and Example 2.

[0048] Fig.14 LSV test graph of Example 1 of the present invention and Comparative Examples 7, 8, 9, 10, 11, and 12 in ethylene glycol small molecules. Detailed implementation manners

[0049] Example 1

[0050] The synthesis mechanism of Ir-PdPtAuNiCu HEANs-C is as Figure 1 shown, and its preparation method is as follows:

[0051] (1) Weigh 10.0 mg of copper acetylacetonate, 14.7 mg of platinum acetylacetonate, 18.2 mg of iridium acetylacetonate, 6.6 mg of palladium chloride, 14.6 mg of chloroauric acid trihydrate, 11.9 mg of nickel chloride hexahydrate, 52.8 mg of ascorbic acid, and 5 mL of oleylamine;

[0052] (2) Transfer the above products into a round-bottom flask and ultrasonicate for half an hour to disperse the solution evenly; install a three-way valve, evacuate and then fill the volumetric flask with nitrogen, and ensure that the experiment is carried out in a nitrogen environment;

[0053] (3) Place the above round-bottom flask in an oil bath at 170 °C and heat for 2 h, then raise the temperature to 200 °C at a heating rate of 6 °C per minute and react for 1 h;

[0054] (4) Wash three times with a mixed solution of cyclohexane: absolute ethanol = 7:1 and then place in a vacuum oven to dry to obtain the high-entropy ultrafine nanostructure nanocomposite Ir-PdPtAuNiCu HEANs;

[0055] (5) Add carbon black in a ratio of ECP-600JD carbon black: Ir-PdPtAuNiCu HEANs = 2:3 and place in an ultrasonic cleaner to ultrasonicate for 0.5 - 2 h to disperse it evenly to form Ir-PdPtAuNiCu HEANs-C.

[0056] Example 2

[0057] This comparative example provides a preparation method of a high-entropy ultrafine nanocatalyst, which is different from Example 1 in that:

[0058] In step (1), iridium acetylacetonate is not added.

[0059] The remaining steps and parameters are the same as those in Example 1.

[0060] Comparative Example 1

[0061] This comparative example provides a method for preparing a high entropy ultrafine nanocatalyst, which differs from Example 1 in that:

[0062] In step (1), only copper acetylacetonate is added.

[0063] The remaining steps and parameters are the same as those in Example 1.

[0064] Comparative Example 2

[0065] This comparative example provides a method for preparing a high entropy ultrafine nanocatalyst, which differs from Example 1 in that:

[0066] In step (1), the content of palladium, platinum and gold sources is half of that in step (1).

[0067] The remaining steps and parameters are the same as those in Example 1.

[0068] Comparative Example 3

[0069] This comparative example provides a method for preparing a high entropy ultrafine nanocatalyst, which differs from Example 1 in that:

[0070] In step (1), the content of palladium, platinum and gold sources is one quarter of that in step (1).

[0071] The remaining steps and parameters are the same as those in Example 1.

[0072] Comparative Example 4

[0073] This comparative example provides a method for preparing a high entropy ultrafine nanocatalyst, which differs from Example 1 in that:

[0074] In step (1), gold acetylacetonate is not added.

[0075] The remaining steps and parameters are the same as those in Example 1.

[0076] Comparative Example 5

[0077] This comparative example provides a method for preparing a high entropy ultrafine nanocatalyst, which differs from Example 1 in that:

[0078] In step (1), nickel acetylacetonate is not added.

[0079] The remaining steps and parameters are the same as those in Example 1.

[0080] Comparative Example 6

[0081] This comparative example provides a method for preparing a high entropy ultrafine nanocatalyst, which differs from Example 1 in that:

[0082] In step (1), copper acetylacetonate is not added.

[0083] The remaining steps and parameters are the same as those in Example 1.

[0084] Comparative Example 7

[0085] This comparative example provides a method for preparing a high entropy ultrafine nanocatalyst, which differs from Example 1 in that:

[0086] In step (1), chloroauric acid and iridium acetylacetonate are not added, but molybdenum acetylacetonate is added.

[0087] The remaining steps and parameters are the same as those in Example 1.

[0088] Comparative Example 8

[0089] This comparative example provides a method for preparing a high entropy ultrafine nanocatalyst, which differs from Example 1 in that:

[0090] In step (1), chloroauric acid and nickel acetylacetonate are not added, but lanthanum acetylacetonate is added.

[0091] The remaining steps and parameters are the same as those in Example 1.

[0092] Comparative Example 9

[0093] This comparative example provides a method for preparing a high entropy ultrafine nanocatalyst, which differs from Example 1 in that:

[0094] In step (1), chloroauric acid and iridium acetylacetonate are not added, but iron acetylacetonate and cobalt acetylacetonate are added.

[0095] The remaining steps and parameters are the same as those in Example 1.

[0096] Comparative Example 10

[0097] This comparative example provides a method for preparing a high entropy ultrafine nanocatalyst, which differs from Example 1 in that:

[0098] In step (1), chloroauric acid and nickel acetylacetonate are not added, but cobalt acetylacetonate is added.

[0099] The remaining steps and parameters are the same as those in Example 1.

[0100] Comparative Example 11

[0101] This comparative example provides a method for preparing a high entropy ultrafine nanocatalyst, which differs from Example 1 in that:

[0102] In step (1), chloroauric acid and nickel acetylacetonate are not added, but iron acetylacetonate is added.

[0103] The remaining steps and parameters are the same as those in Example 1.

[0104] Comparative Example 12

[0105] This comparative example provides a method for preparing a high entropy ultrafine nanocatalyst, which differs from Example 1 in that:

[0106] In step (1), copper acetylacetonate and nickel acetylacetonate are not added.

[0107] The remaining steps and parameters are the same as those in Example 1.

[0108] Test Example 1

[0109] (1) The morphology of the high entropy nanocatalyst prepared in Example 1 was analyzed and the following results were obtained: Figure 1 The high entropy nanocatalyst transmission electron microscope TEM image shown. Figure 1 It can be seen that the high entropy nanoparticle structure and the average particle size are 5.45nm. From the ICP-MS, TEM and XPS element content analysis, it can be known that the Ir content is less than 5%, indicating that the Ir element is a doping element. Figure 2 It can be seen that Example 2 has an obvious high-entropy nanoparticle structure and an average particle size of 5.5 nm, and except for the Ir element, the relative contents of other elements are basically consistent with those in Example 1.

[0110] (2) Figure 3 is the XRD pattern of the high entropy nanocatalyst of Examples 1-2 and Comparative Example 1 (wherein, the curve Ir-PdPtAuNiCu HEANs is the XRD pattern of the high entropy nanomaterial Ir-PdPtAuNiCu HEANs prepared in Example 1, the curve PdPtAuNiCu HEANs is the XRD pattern of the high entropy nanocatalyst prepared from the high entropy nanomaterial PdPtAuNiCu HEANs in Example 2, and the curve Cu NPs is the XRD pattern of the nanomaterial Cu NPs in Comparative Example 1). Figure 3 It can be seen that the PdPtAuNiCu HEANs diffraction peaks corresponding to the Cu(111) plane at 43.1° and 50.2° appear between the copper standard card and the iridium, palladium, platinum and gold standard cards. The three peaks of 40.2°, 46.6° and 68.1° prove the formation of the PdPtAuNiCu HEANs alloy structure. With the doping of Ir to form Ir-PdPtAuNiCu HEANs, the corresponding reflections significantly reduce the diffraction angles to 39.6°, 46.1° and 67.0°, respectively.

[0111] (3) The high entropy nanocatalysts prepared in Example 1 and Example 2 were assembled into electrodes, and the performance of ethylene glycol electro-oxidation and hydrogen evolution was tested and compared with commercial Pd / C and Pt / C. The specific assembly method is as follows:

[0112] 5 mg of high entropy carbon-based nanocatalyst and 10 μL of Nafion binder were dispersed in 990 μL of isopropanol solution and dispersed evenly by ultrasonication for 0.5 h. Coated on a glassy carbon electrode and dried naturally for use. Then, 10 μL of ink was transferred to the glassy carbon electrode to obtain a working electrode. Mercury-mercuric oxide was used as a reference electrode, a carbon rod was used as a counter electrode, and the electrolyte was a 1 M NaOH solution and a 0.5 M ethylene glycol biomass small molecule solution.

[0113] Figure 4 This is the LSV curve of Ir-PdPtAuNiCu HEANs-C in 1M NaOH solution and 1M NaOH+biomass small molecule solution. Figure 4 It can be seen that Ir-PdPtAuNiCuHEANs-C has an obvious catalytic effect on ethylene glycol small molecules, and the starting potential is only 0.245 V relative to the standard hydrogen electrode.

[0114] Figure 5 The LSV diagrams of the two high entropy nanocatalysts in Example 1 and Example 2 of the present invention in ethylene glycol solution show that the two high entropy nanocatalysts show certain electrooxidation activity of biomass alcohol. Among them, Ir-PdPtAuNiCu HEANs-C has the highest catalytic activity, reaching 2.41A cm at 0.724V. -2 , which are 2.17, 12.7 and 10.0 times of PdPtAuNiCuHEANs-C, Pt / C and Pd / C respectively, and Ir-PdPtAuNiCu HEANs-C has the lowest catalytic onset potential, which is lower than PdPtAuNiCu HEANs-C (0.29 V), Pt / C (0.45 V) and Pd / C (0.46 V).

[0115] Figure 6 The LSV graphs of the three high entropy nanocatalysts in ethylene glycol solution of Example 1 and Comparative Examples 2 and 3 of the present invention clearly show that the three high entropy nanocatalysts exhibit certain electro-oxidation activity for biomass alcohol, among which Ir-PdPtAuNiCu HEANs-C has the highest catalytic activity, indicating that the catalyst is the optimal ratio.

[0116] Figure 7 The LSV diagrams of the three high entropy nanocatalysts in Example 1 of the present invention and Comparative Examples 4, 5, and 6 in ethylene glycol solution show that the three high entropy nanocatalysts exhibit certain activity in the electro-oxidation of biomass alcohols, among which Ir-PdPtAuNiCu HEANs-C has the highest catalytic activity.

[0117] Figure 8After the products prepared in Example 1 and Example 2 were assembled into electrodes, IT tests were performed in 1M NaOH+EG solution. We found that the Ir-PdPtAuNiCu HEANs-C catalyst had an initial current density of After five hours, the maximum current density is reached The current density after twenty hours was 147% of the initial value.

[0118] Fig. 9 After the products prepared in Example 1 and Example 2 were assembled into electrodes, cyclic voltammetry was performed in 1M NaOH+EG solution. It was found that the current of the Ir-PdPtAuNiCu HEANs-C catalyst dropped to 99.4% of the initial state after nearly 1000 cycles of catalysis.

[0119] Fig.10 The products prepared in Example 1 and Example 2 were assembled into electrodes and subjected to IT testing. The products in the electrolyte were collected for nuclear magnetic resonance testing. It was found that the Faraday efficiency of ethylene glycol for the Ir-PdPtAuNiCu HEANs-C catalyst was the highest at 0.724 V, reaching 88%.

[0120] Fig.11 The products prepared in Example 1 and Example 2 were assembled into electrodes and subjected to IT testing. The products in the electrolyte were collected and tested by nuclear magnetic resonance analysis. It was found that after ten hours of electrolysis, the Faraday efficiency of ethylene glycol of the Ir-PdPtAuNiCu HEANs-C catalyst was maintained at about 80%.

[0121] Fig.12 is the LSV curve of Example 1 and Example 2 in 1M NaOH solution. Fig.12 It can be seen that the catalysts have a significant catalytic effect on water electrolysis, among which PdPtAuNiCu HEANs-C has the highest catalytic activity. Ir-PdPtAuNiCu HEANs-C The performance is better than commercial Pt / C.

[0122] Fig.13 This is a graph showing the relationship between the current density and the electrolysis time of the membraneless flow electrolyzer [(-)PdPtAuNiCu||Ir-PdPtAuNiCu(+)] assembled by Example 1 and Example 2. It can be found that the current density does not decrease significantly within 1200 hours, indicating the ultra-stability of the catalyst.

[0123] Fig.14The LSV diagrams of seven high entropy nanocatalysts in ethylene glycol solution of Example 1 of the present invention and Comparative Examples 7, 8, 9, 10, 11, and 12 show that the seven high entropy nanocatalysts exhibit certain activity in the electro-oxidation of biomass alcohols, among which Ir-PdPtAuNiCu HEANs-C has the highest catalytic activity.

[0124] In summary, the present invention prepares high entropy nanocatalysts, and the metals used are all transition metals, which reduces the cost, and has extremely strong stability and low starting potential, which is suitable for industrial production. It can also be coupled with cathode hydrogen evolution catalysis and can be applied to various energy storage fields.

Claims

1. A method for preparing a bifunctional ultrafine high entropy nanocatalyst for electrochemical oxidation of ethylene glycol coupled with electrolysis to produce hydrogen, characterized in that: The following steps are involved: (1) A metal source, a reducing agent and a surfactant are mixed and dispersed, and a bifunctional ultrafine high entropy nanomaterial is synthesized by a solvothermal method at a temperature below 200° C. under the protection of an inert atmosphere; The metal source contains a copper source, a platinum source, a nickel source, a palladium source and a gold source; (2) The high entropy ultrafine nanomaterial obtained in step (1) is mixed and dispersed with a carbon material to obtain the bifunctional ultrafine high entropy nanocatalyst.

2. The preparation method according to claim 1, characterized in that: In step (1), the metal source further comprises an iridium source; The copper source, platinum source and iridium source are copper acetylacetonate, platinum acetylacetonate and iridium acetylacetonate respectively. The nickel source is nickel chloride or nickel acetylacetonate, The palladium source is palladium chloride or palladium acetylacetonate, The gold source is chloroauric acid; The reducing agent is ascorbic acid, The surfactant is oleylamine.

3. The preparation method according to claim 2, characterized in that: The molar mass ratio of copper element: nickel element: palladium element: platinum element: iridium element: gold element in the metal source is 1:1:1:1:1:1 or 3:2:3:3:3:

3.

4. The preparation method according to claim 1, characterized in that: In step (1), the conditions of the solvothermal method are: first react at a reaction temperature of 170° C. for 2 h, then increase the reaction temperature to 200° C., and react at 200° C. for 1 h.

5. The preparation method according to claim 4, characterized in that: The heating rate is 6°C / min.

6. The preparation method according to claim 1, characterized in that: In step (1), washing with an organic solvent is performed after heating the reaction; The organic solvent is a mixed solution of cyclohexane and anhydrous ethanol, and the volume ratio of the cyclohexane to the anhydrous ethanol is 7:

1.

7. The preparation method according to claim 1, characterized in that: In step (2), the carbon material is ECP-600JD carbon black; The mass ratio of the carbon material to the dual-functional ultrafine high-entropy nanomaterial is 2:1-3.

8. A bifunctional ultrafine high entropy nanocatalyst prepared by the preparation method according to any one of claims 1 to 7.

9. The bifunctional ultrafine high entropy nanocatalyst according to claim 8, characterized in that: The particle size of the ultrafine high entropy nanocatalyst is 3-7 nm.

10. Use of the bifunctional ultrafine high entropy nanocatalyst according to claim 8 in catalyzing the electrochemical oxidation of ethylene glycol coupled with electrolysis to produce hydrogen.

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