Ni3S2 / Ni (OH) 2 / metal phthalocyanine heterojunction self-supporting electrocatalyst as well as preparation method and application thereof

Abstract

The invention discloses a Ni3S2 / Ni (OH) 2 / metal phthalocyanine heterojunction self-supporting electrocatalyst as well as a preparation method and application thereof. According to the catalyst, foamed nickel serves as a substrate and a nickel source, a Ni3S2 / Ni (OH) 2 nanosheet array precursor grows in situ through one-step hydrothermal, metal phthalocyanine is loaded through solvothermal, and the Ni3S2 / Ni (OH) 2 / metal phthalocyanine composite electrode material with a multistage heterogeneous interface is formed. The material can be used for preparing 2, 5-furandicarboxylic acid (FDCA) through efficient electro-catalysis of deep oxidation of 5-hydroxymethylfurfural (HMF) in an alkaline solution at room temperature; the metal phthalocyanine molecular catalyst and the nickel-based composite material are combined for preparing the self-supporting electrode for the first time, efficient and high-selectivity total oxidation of HMF is achieved in an alkaline environment, the structure avoids using a binder, the conductivity, the structural stability and the active site exposure degree are enhanced, and industrial large-scale preparation is facilitated.

Description

Technical Field

[0001] This invention belongs to the field of biomass electrocatalytic conversion, specifically relating to a Ni3S2 / Ni(OH)2 / metal phthalocyanine heterostructure self-supporting electrocatalyst, its preparation method, and its application. Background Technology

[0002] 5-Hydroxymethylfurfural (HMF) is an important biomass platform compound. Its complete oxidation product, 2,5-furandicarboxylic acid (FDCA), is a key monomer for the synthesis of bio-based polyesters and can replace petroleum-based feedstock terephthalic acid, showing broad market prospects. Therefore, the electrocatalytic oxidation of HMF to FDCA has become a promising anodic alternative reaction in coupled-cathode hydrogen production systems. The key to achieving efficient and highly selective conversion of this reaction lies in developing high-performance, low-cost electrocatalysts.

[0003] Among numerous candidate materials, nickel-based sulfides (such as Ni3S2) have attracted widespread attention due to their good conductivity, abundant active sites, and low cost. Previous studies have reported various strategies to enhance their catalytic performance, such as: stepwise construction of Ni(OH)2 / Ni3S2 heterojunction electrodes by introducing nickel salts to improve selectivity and reaction kinetics for FDCA (CN117966201A); optimization of the electronic structure of Ni3S2 using Co doping (Advanced Science 2022, 9, 2200957); and designing CeO2@Co-Ni3S2 catalysts with hierarchical structures to synergistically accelerate Ni 3+ Generate and enhance HMF adsorption (Advanced Functional Materials 2025, 9, e12292); and construct highly active NiOOH-SO through Cu doping and surface reconstruction strategies. x Phase (Advanced Energy Materials2024, 14, 2303557).

[0004] On the other hand, metal phthalocyanine (MPc) molecules with a well-defined metal center and a unique M−N4 coordination environment have shown significant potential in the field of electrocatalysis. For example, a study used copper phthalocyanine (CuPc) in situ supported on Co3O4 for the electrooxidation of HMF under neutral conditions (Journal of Colloid and Interface Science, 2024, 654, 731-739). At 1.5 V vs RHE, a 64% yield of 5-formyl-2-furanoic acid (FFCA) was achieved, but the yield of the fully oxidized product FDCA was only 18%, indicating that this system is difficult to achieve deep oxidation of HMF under neutral conditions.

[0005] Based on the above research status, this invention innovatively combines metal phthalocyanine (MPc) with Ni3S2 / Ni(OH)2 heterojunction to construct a self-supporting composite electrode material Ni3S2 / Ni(OH)2 / MPc, and applies it to a strongly alkaline electrolysis system to achieve efficient and highly selective deep oxidation of HMF to the high-value-added product FDCA. Summary of the Invention

[0006] This invention discloses a Ni3S2 / Ni(OH)2 / metal phthalocyanine heterojunction self-supporting electrocatalyst and its preparation method, as well as its application in the electrocatalytic oxidation of 5-hydroxymethylfurfural (HMF) to prepare 2,5-furandicarboxylic acid (FDCA).

[0007] The technical solution of the present invention is as follows:

[0008] A method for preparing a Ni3S2 / Ni(OH)2 / metal phthalocyanine heterojunction self-supported electrocatalyst includes the following steps:

[0009] Step 1: Using nickel foam as a self-supporting substrate and nickel source, place it in an aqueous solution of thiourea and carry out a hydrothermal reaction at 100~180 ℃ for 4~8 h. After that, take it out, rinse and dry it to obtain Ni3S2 / Ni(OH)2 precursor material on the nickel foam substrate.

[0010] The aqueous solution concentration of thiourea is 10~30 µM, preferably 15 µM;

[0011] The preferred hydrothermal reaction temperature is 150 ℃ and the preferred reaction time is 5 h;

[0012] Step 2: Add the precursor material obtained in Step 1 to an ethanol solution of metal phthalocyanine and carry out a solvothermal reaction at 100~150 °C for 6~10 h. Then take it out, rinse and dry to obtain the Ni3S2 / Ni(OH)2 / metal phthalocyanine heterojunction self-supported electrocatalyst (denoted as: Ni3S2 / Ni(OH)2 / MPc).

[0013] The metal phthalocyanine is selected from cobalt phthalocyanine, copper phthalocyanine, iron phthalocyanine, and zinc phthalocyanine, with cobalt phthalocyanine being the most preferred.

[0014] In an ethanol solution of metal phthalocyanine, the concentration of metal phthalocyanine is 0.1~1 mg / mL, preferably 0.05 mg / mL;

[0015] The preferred solvothermal reaction temperature is 120 °C and the reaction time is 6 h.

[0016] In this invention, the preparation method of metal phthalocyanine is as follows:

[0017] Acid anhydride, urea, ammonium compound, and transition metal salt were mixed, ground evenly, and then transferred to a muffle furnace. The furnace was heated to 220 °C for 3 hours in air at a rate of 3 °C / min. After that, the mixture was removed, washed, and dried to obtain metallic titanium cyanide.

[0018] The preferred molar ratio of acid anhydride, urea, ammonium compound, and transition metal salt is 6:45:12:1.1;

[0019] The acid anhydride is selected from at least one of pyromellitic dianhydride and phthalic anhydride;

[0020] The ammonium compound is selected from at least one of ammonium chloride and ammonium molybdate;

[0021] The transition metal salt is selected from at least one of cobalt chloride hexahydrate, copper acetate monohydrate, zinc chloride, and ferric chloride hexahydrate.

[0022] This invention relates to a Ni3S2 / Ni(OH)2 / metal phthalocyanine heterojunction self-supporting electrocatalyst prepared by the above-mentioned preparation method.

[0023] The Ni3S2 / Ni(OH)2 / metal phthalocyanine heterostructure self-supported electrocatalyst of this invention can be used in the electrocatalytic oxidation of 5-hydroxymethylfurfural (HMF) to prepare 2,5-furandicarboxylic acid (FDCA). Specific application methods are as follows:

[0024] In an H-type electrolytic cell containing a proton exchange membrane, a three-electrode system was constructed using a Ni3S2 / Ni(OH)2 / metal phthalocyanine heterojunction self-supporting electrocatalyst as the anode (working electrode), a platinum sheet as the cathode (counter electrode), and an Hg / HgO electrode as the reference electrode. An alkaline solution containing 5-hydroxymethylfurfural was added to the anode chamber as the anolyte, and an alkaline solution was added to the cathode chamber as the cathode electrolyte. The anolyte was stirred and electrolyzed at a constant potential under room temperature and atmospheric pressure to produce 2,5-furandicarboxylic acid.

[0025] The preferred alkaline solution for the anode and cathode chambers is a 1M KOH solution.

[0026] In the anolyte, the concentration of 5-hydroxymethylfurfural is 10~100 mM, preferably 20 mM;

[0027] The preferred electrolysis potential is 1.3~1.7 V vs. RHE, and the electrolysis time is 1~5 h; the more preferred electrolysis potential is 1.425 V vs. RHE, and the electrolysis time is 2 h.

[0028] The beneficial effects of this invention are as follows:

[0029] This invention is the first to propose using metal phthalocyanine-modified nickel-based sulfide and hydroxide heterojunction electrode materials as anode electrodes, achieving highly selective electrocatalytic deep oxidation of 5-hydroxymethylfurfural (HMF) to 2,5-furandicarboxylic acid (FDCA): HMF conversion ≥95%, FDCA yield ≥90%, and Faraday efficiency ≥90%.

[0030] The catalyst of this invention uses inexpensive and readily available nickel, sulfur, and transition metal (Co, Cu, Fe, Zn) phthalocyanines as raw materials, avoiding the use of precious metals and significantly reducing material costs. The electrode material is directly grown on a conductive substrate, exhibiting strong bonding and good structural stability during long-term electrolysis, and is easy to separate and reuse.

[0031] The catalyst preparation method of this invention is simple and easy to mass-produce, which provides a new idea for designing novel composite electrode materials for efficient and highly selective electrocatalytic conversion of biomass molecules. This strategy can be extended to other metal phthalocyanine and support systems. Attached Figure Description

[0032] Figure 1 Scanning electron microscope (SEM) image of Ni3S2 / Ni(OH)2 / CoPc in Example 1.

[0033] Figure 2 X-ray diffraction (XRD) pattern of Ni3S2 / Ni(OH)2 / CoPc in Example 1.

[0034] Figure 3 Linear sweep voltammograms (LSVs) of different catalyst materials in Examples 1-4.

[0035] Figure 4 Electrolysis results of the catalysts in Examples 1-4 at 1.425 V vs. RHE.

[0036] Figure 5 The results of repeated electrolysis of the Ni3S2 / Ni(OH)2 / CoPc catalyst in Example 1. Detailed Implementation

[0037] To facilitate understanding of the present invention, specific embodiments will be further described below. These embodiments are for illustrative purposes only and do not limit the scope of the invention. The technical terms used herein are for the purpose of describing specific embodiments only and are not intended to limit the scope of protection of the present invention.

[0038] Example 1:

[0039] 0.6098 g of pyromellitic dianhydride, 0.4740 g of phthalic anhydride, 2.721 g of urea, 0.6419 g of ammonium chloride, 0.0034 g of ammonium molybdate, and 0.2617 g of cobalt chloride hexahydrate were mixed and ground. The mixture was then heated in a muffle furnace at 3°C ​​for [time missing]. -1 The temperature was raised to 220 °C and held for 3 hours. After the reaction was completed, the mixture was washed successively with deionized water, acetone and ethanol, and then dried under vacuum at 60 °C for 12 hours to obtain cobalt phthalocyanine powder.

[0040] Nickel foam was used as the substrate and nickel source, and placed in a 14.45 µM thiourea aqueous solution. The mixture was subjected to a hydrothermal reaction at 150 °C for 5 hours. After that, it was taken out, rinsed and dried to obtain the Ni3S2 / Ni(OH)2 precursor material.

[0041] 1 mg of cobalt phthalocyanine powder was weighed and dispersed in 20 mL of ethanol. Ni3S2 / Ni(OH)2 precursor material was added and the mixture was solvothermal reacted in a hydrothermal reactor at 120 °C for 6 h. After the reaction, the material was rinsed and dried to obtain the cobalt phthalocyanine-modified Ni3S2 / Ni(OH)2 / CoPc heterojunction catalyst material.

[0042] Figure 1 The image shows the SEM morphology of Ni3S2 / Ni(OH)2 / CoPc, which reveals that the catalyst exhibits a 2D nanosheet morphology. Figure 2 The XRD pattern of Ni3S2 / Ni(OH)2 / CoPc shows that the phase composition of the catalyst is mainly composed of Ni3S2 and Ni(OH)2.

[0043] In an H-type electrolytic cell containing a proton exchange membrane diaphragm, a three-electrode system was constructed using Ni3S2 / Ni(OH)2 / CoPc as the working electrode, a platinum sheet as the counter electrode, and an Hg / HgO electrode as the reference electrode. 20 mM 5-hydroxymethylfurfural was added to a 1 M KOH solution in the anode chamber as the anolyte, and a 1 M KOH solution was added to the cathode chamber as the cathode electrolyte. The anolytes were stirred at room temperature and atmospheric pressure, and cyclic voltammetry (LSV) curves were obtained. Figure 3 The current density shown on the screen is 139 mA / cm² at 1.425 V vs. RHE. 2 Electrolysis at 1.425 V vs. RHE for 2 hours yielded 96% of 2,5-furandicarboxylic acid, 98% of 5-hydroxymethylfurfural, and a Faraday efficiency of 99%. Figure 4 ). Figure 5 The results of six repeated electrolysis cycles show that the conversion rate of 5-hydroxymethylfurfural is consistently above 95%, the yield of 2,5-furandicarboxylic acid is ≥90%, and the Faraday efficiency is ≥90%.

[0044] Example 2:

[0045] The preparation method and process are the same as in Example 1, except that the metal salt is adjusted to 0.2196 g of copper acetate monohydrate, while other amounts remain unchanged. Repeating a similar process yields the Ni3S2 / Ni(OH)2 / CuPc catalytic electrode. Using it as the working electrode, the current density at 1.425 V vs. RHE is 116 mA / cm². 2 ( Figure 3 Applying 1.425 V vs. RHE electrolysis for 2 hours yielded 95% 2,5-furandicarboxylic acid, ~100% conversion of 5-hydroxymethylfurfural, and a Faraday efficiency of 97%. Figure 4 ).

[0046] Example 3:

[0047] The preparation method and process are the same as in Example 1, except that the metal salt is adjusted to 0.2973 g of ferric chloride hexahydrate, while other amounts remain unchanged. Repeating a similar process yields the Ni3S2 / Ni(OH)2 / FePc catalytic electrode. Using it as the working electrode, the current density at 1.425 V vs. RHE is 110 mA / cm². 2 ( Figure 3 Applying 1.425 V vs. RHE electrolysis for 2 hours yielded 80% 2,5-furandicarboxylic acid and 87% 5-hydroxymethylfurfural, with a Faraday efficiency of 80%. Figure 4 ).

[0048] Example 4:

[0049] The preparation method and process were the same as in Example 1, except that the metal salt was adjusted to 0.1499 g of zinc chloride, while other amounts remained unchanged. A Ni3S2 / Ni(OH)2 / ZnPc catalytic electrode was obtained. Using it as the working electrode, the current density at 1.425 V vs. RHE was 106 mA / cm². 2 ( Figure 3 Applying 1.425 V vs. RHE electrolysis for 2 hours yielded 80% 2,5-furandicarboxylic acid, ~88% conversion of 5-hydroxymethylfurfural, and a Faraday efficiency of 83%. Figure 4 ).

Claims

1. A method for preparing a Ni3S2 / Ni(OH)2 / metal phthalocyanine heterojunction self-supporting electrocatalyst, characterized in that, Includes the following steps: Step 1: Using nickel foam as a self-supporting substrate and nickel source, place it in an aqueous solution of thiourea and carry out a hydrothermal reaction at 100~180 ℃ for 4~8 h. After that, take it out, rinse and dry it to obtain Ni3S2 / Ni(OH)2 precursor material on the nickel foam substrate. Step 2: Add the precursor material obtained in Step 1 to an ethanol solution of metal phthalocyanine and carry out a solvothermal reaction at 100~150 °C for 6~10 h. Then take it out, rinse and dry it to obtain the Ni3S2 / Ni(OH)2 / metal phthalocyanine heterostructure self-supporting electrocatalyst. Metal phthalocyanines are selected from cobalt phthalocyanine, copper phthalocyanine, iron phthalocyanine, and zinc phthalocyanine.

2. The preparation method of the Ni3S2 / Ni(OH)2 / metal phthalocyanine heterojunction self-supporting electrocatalyst as described in claim 1, characterized in that, In step one, the concentration of the thiourea aqueous solution is 10~30 µM.

3. The preparation method of the Ni3S2 / Ni(OH)2 / metal phthalocyanine heterojunction self-supported electrocatalyst as described in claim 1, characterized in that, In step two, the concentration of the metal phthalocyanine in the ethanol solution is 0.1~1 mg / mL.

4. The preparation method of the Ni3S2 / Ni(OH)2 / metal phthalocyanine heterojunction self-supported electrocatalyst as described in claim 1, characterized in that, Metal phthalocyanines are prepared by the following method: Acid anhydride, urea, ammonium compound, and transition metal salt were mixed, ground evenly, and then transferred to a muffle furnace. The furnace was heated to 220 °C for 3 hours in air at a rate of 3 °C / min. After that, the mixture was removed, washed, and dried to obtain metallic titanium cyanide. The acid anhydride is selected from at least one of pyromellitic dianhydride and phthalic anhydride; The ammonium compound is selected from at least one of ammonium chloride and ammonium molybdate; The transition metal salt is selected from at least one of cobalt chloride hexahydrate, copper acetate monohydrate, zinc chloride, and ferric chloride hexahydrate.

5. The preparation method of the Ni3S2 / Ni(OH)2 / metal phthalocyanine heterojunction self-supporting electrocatalyst as described in claim 4, characterized in that, The molar ratio of acid anhydride, urea, ammonium compound, and transition metal salt is 6:45:12:1.

1.

6. The Ni3S2 / Ni(OH)2 / metal phthalocyanine heterostructure self-supporting electrocatalyst prepared by the preparation method according to any one of claims 1 to 5.

7. The application of the Ni3S2 / Ni(OH)2 / metal phthalocyanine heterostructure self-supporting electrocatalyst as described in claim 6 in the electrocatalytic oxidation of 5-hydroxymethylfurfural to prepare 2,5-furandicarboxylic acid.

8. The application as described in claim 7, characterized in that, The method is as follows: In an H-type electrolytic cell containing a proton exchange membrane, a three-electrode system was constructed using a Ni3S2 / Ni(OH)2 / metal phthalocyanine heterojunction self-supporting electrocatalyst as the anode, a platinum sheet as the cathode, and an Hg / HgO electrode as the reference electrode. An alkaline solution containing 5-hydroxymethylfurfural was added to the anode chamber as the anolyte, and an alkaline solution was added to the cathode chamber as the cathode electrolyte. The anolyte was stirred and electrolyzed at a constant potential under room temperature and atmospheric pressure to produce 2,5-furandicarboxylic acid.

9. The application as described in claim 8, characterized in that, The alkaline solution in the anode and cathode chambers is a 1M KOH solution; the concentration of 5-hydroxymethylfurfural in the anolyte is 10~100 mM.

10. The application as described in claim 8, characterized in that, Electrolysis potential 1.3~1.7 V vs. RHE, electrolysis time 1~5 h.

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