Preparation method of defect-rich cobalt-nickel-based amorphous sulfide and application of defect-rich cobalt-nickel-based amorphous sulfide in electrocatalytic oxidation of 5-hydroxymethylfurfural

Abstract

The invention belongs to the technical field of electro-catalysis, and discloses a preparation method of defect-rich cobalt-nickel-based amorphous sulfide and application of the defect-rich cobalt-nickel-based amorphous sulfide in electro-catalytic oxidation of 5-hydroxymethylfurfural. The preparation method comprises the following steps that firstly, cobalt-nickel-based bimetal hydroxide is obtained through liquid phase growth and ion exchange; and vulcanizing by adopting an ethanol modified surface vulcanization method to synthesize the defect-rich cobalt-nickel-based amorphous sulfide (CoNiS-A (at) NF). Finally, the CoNiS-A-coated NF is used as an electrocatalyst for electrochemical testing, the CoNiS-A-coated NF is applied to preparation of FDCA through HMF electrocatalytic oxidation, and the material has excellent HMF electrocatalytic oxidation performance and stable cycle performance.

Description

Technical Field

[0001] This invention relates to the field of electrocatalysis technology, specifically to a method for preparing defect-rich cobalt-nickel-based amorphous sulfides and their application in the electrocatalytic oxidation of 5-hydroxymethylfurfural. Background Technology

[0002] Biomass, as a renewable non-fossil resource, has been recognized as a potential alternative to meet the stringent requirements of environmental protection and sustainable development. 5-Hydroxymethylfurfural (HMF) is one of the valuable intermediates identified by the U.S. Department of Energy for use in chemical, fuel, and other biorenewable materials. Its oxidation product, 2,5-furandicarboxylic acid (FDCA), is widely recognized as an outstanding monomer due to its potential applications in polymer resource development. In the research of electrochemical catalysts, considering the scarcity of precious metals, the development of green and inexpensive, highly efficient non-precious metal catalysts such as Co, Ni, and Fe is crucial. Although the economic burden can be reduced by decreasing the loading or controlling the morphology, developing non-precious metal catalysts and more efficient synthesis methods is the ultimate way to reduce costs, and non-precious metal-based electrocatalysts are gradually showing great potential. Based on this, this project investigated a method for preparing defect-rich cobalt-nickel-based amorphous sulfides and their application in the electrocatalytic oxidation of 5-hydroxymethylfurfural. Summary of the Invention

[0003] The purpose of this invention is to overcome the shortcomings of existing technologies and provide a novel method for preparing cobalt-nickel-based amorphous sulfides and applying it to the electrocatalytic oxidation of 5-hydroxymethylfurfural (HMF). A cobalt-nickel-based bimetallic hydroxide was obtained through liquid-phase growth and ion exchange, followed by sulfidation using an ethanol-modified surface sulfidation method to synthesize a defect-rich cobalt-nickel-based amorphous sulfide (CoNiS-A@NF). Finally, CoNiS-A@NF was used as an electrocatalyst for electrochemical testing, demonstrating excellent HMF electrocatalytic oxidation performance and stable cycling performance in the preparation of FDCA.

[0004] The technical solution of the present invention is as follows:

[0005] A method for preparing cobalt-nickel-based amorphous sulfides and their application in the electrocatalytic oxidation of 5-hydroxymethylfurfural, the method comprising the following steps:

[0006] (1) Nickel foam pretreatment: First, cut NF into 1cm×3cm sizes and use 3ML -1 The NF was ultrasonically cleaned with hydrochloric acid aqueous solution for 30 min to remove the oxide layer on the surface. Then, the NF was ultrasonically cleaned in anhydrous ethanol and deionized water for 10 min each. Finally, it was dried in a vacuum oven at 60℃ for 6 h to obtain clean NF.

[0007] (2) Preparation of Co-MOF@NF: An aqueous solution containing C4H6N2 was added to a Co(NO3)2·6H2O solution, and the solution was magnetically stirred to ensure uniform mixing. Then, a clean piece of NF (protected by PTFE tape on the top) was suspended 2 cm below the surface of the mixed solution and allowed to react at room temperature for 4 h. After the reaction was completed, the sample was removed, washed with anhydrous ethanol, and dried in a vacuum oven at 60 °C for 6 h.

[0008] (3) Preparation of CoNi LDH@NF precursor: The sample obtained in step (2) was added to an ethanol solution containing Ni(NO3)2·6H2O and etched for 1 h under magnetic stirring. After the reaction was completed, the sample was taken out, washed with ultrapure water and dried in a vacuum oven at 60℃ for 6 h to obtain cobalt-nickel based bimetallic hydroxide.

[0009] (4) Preparation of cobalt-nickel based amorphous sulfides: The sample obtained in step (3) was added to an ethanol solution containing Na2S·9H2O. After reacting for 24 hours, the sample was taken out, washed with anhydrous ethanol, and then dried in a vacuum oven at 60°C for 6 hours to obtain the sample cobalt-nickel based amorphous sulfides.

[0010] The essential features of this invention are:

[0011] This invention first uses nickel foam as a self-supporting substrate to obtain CoNi-based bimetallic hydroxide CoNi LDH@NF through liquid-phase growth and ion exchange. Then, it employs an ethanol-modified surface sulfidation method to synthesize defect-rich CoNi-based amorphous sulfide CoNiS-A@NF. This material is then used as a catalyst for the electrochemical oxidation of 5-hydroxymethylfurfural (HMF) to prepare 2,5-furandicarboxylic acid (FDCA).

[0012] The results show that the cobalt-nickel based amorphous sulfide CoNiS-A@NF exhibits excellent electrocatalytic performance in the oxidation of HMF. In a 1.0 M KOH and 10 mM HMF electrolyte, the CoNiS-A catalyst requires only a potential of 1.37 V vs. RHE to reach 100 mA cm⁻¹. -2 The current density was [value missing]. After constant potential electrolysis at 1.475 V vs. RHE, the HMF conversion reached 98.5%, and the yield, Faraday efficiency, and production rate of FDCA reached 97.1%, 96.9%, and 380.0 μmol / cm³, respectively. -2 h -1 This surpasses most currently reported catalysts. Furthermore, the catalyst maintained good catalytic stability even after 11 cycles of electrolysis. Attached Figure Description

[0013] Figure 1The X-ray diffraction pattern is shown for the cobalt-nickel based amorphous sulfide CoNiS-A@NF electrocatalyst prepared in this invention.

[0014] Figure 2 Scanning electron microscope image of the cobalt-nickel based amorphous sulfide CoNiS-A@NF electrocatalyst prepared in this invention.

[0015] Figure 3 Transmission electron microscope image of the cobalt-nickel based amorphous sulfide CoNiS-A@NF electrocatalyst prepared in this invention.

[0016] Figure 4 The graph shows the HMF oxidation performance of the cobalt-nickel based amorphous sulfide CoNiS-A@NF electrocatalyst prepared in this invention at different potentials.

[0017] Figure 5 The graph shows the HMF oxidation performance of the cobalt-nickel based amorphous sulfide CoNiS-A@NF electrocatalyst prepared in this invention after 11 consecutive electrolysis experiments. Detailed Implementation

[0018] Example 1

[0019] Step 1: Select nickel foam (NF) with a three-dimensional framework as the substrate for growing the metal-organic framework (MOF). First, cut the NF to a 1cm × 3cm size and use 3ml of [material name missing]... -1 The NF was ultrasonically cleaned with hydrochloric acid aqueous solution for 30 min to remove the oxide layer on the surface. Then, the NF was ultrasonically cleaned in anhydrous ethanol and deionized water for 10 min each. Finally, it was dried in a vacuum oven at 60℃ for 6 h to obtain clean NF.

[0020] Step Two: First, add an aqueous solution containing C4H6N2 (0.4M, 40ml) to a Co(NO3)2·6H2O (0.05M, 40ml) solution, and stir magnetically to mix the solution thoroughly. Then, suspend a clean piece of NF (protected at the top with PTFE tape) 2cm below the surface of the mixed solution and allow it to react at room temperature for 4 hours. After the reaction is complete, remove the sample, wash it with anhydrous ethanol, and dry it in a vacuum oven at 60℃ for 6 hours to obtain the Co-MOF sample.

[0021] Step 3: Add the sample obtained in Step 2 to an ethanol solution (80 ml) containing 0.232 g Ni(NO3)2·6H2O, and carry out ion exchange under magnetic stirring. After reacting for 1 h, take out the sample, wash it with ultrapure water, and dry it in a vacuum oven at 60 ℃ for 6 h to obtain the sample CoNi LDH@NF.

[0022] Step 4: Add the sample obtained in Step 3 to Na2S·9H2O (19.2g) ethanol solution (80ml), react for 24h, take out the sample, wash it with anhydrous ethanol, and dry it in a vacuum oven at 60℃ for 6h to obtain the sample CoNiS-A@NF electrocatalyst.

[0023] The electrocatalytic oxidation performance of HMF was measured using a Metrohm Autolab PGSTAT 302N electrochemical workstation. A standard three-electrode system was employed, using 1.0 M KOH (pH = 14) solution as the electrolyte, 10 mM HMF as the substrate, CoNiS-A@NF electrocatalyst as the working electrode (electrolyte submerged 1 cm × 1 cm above the electrode), an Hg / HgO electrode as the reference electrode, and a Φ = 5 mm graphite electrode as the counter electrode. The reaction was carried out in a 10 mL H-type electrolytic cell, with two chambers separated by a Nafion 117 proton exchange membrane. All potentials were calibrated relative to the reversible hydrogen electrode (RHE), and the potential transitions were performed according to the Nernst equation: E vs.RHE =E vs.Hg / HgO +0.0592×pH+0.098V. Electrolysis products were determined by high-performance liquid chromatography.

[0024] Figure 1 The X-ray diffraction pattern of the cobalt-nickel based amorphous sulfide CoNiS-A@NF electrocatalyst prepared in this invention shows that there are no obvious diffraction peaks in its XRD pattern, indicating that CoNiS-A@NF has an amorphous structure.

[0025] Figure 2 The scanning electron microscope image of the cobalt-nickel based amorphous sulfide CoNiS-A@NF electrocatalyst prepared in this invention shows that the catalyst surface has a nanoarray structure and forms interconnected ultrathin nanosheets.

[0026] Figure 3 The image shows a transmission electron microscope image of the cobalt-nickel based amorphous sulfide CoNiS-A@NF electrocatalyst prepared in this invention. No obvious lattice fringes are observed in the image, and the absence of the catalyst lattice indicates the amorphous structure of the nanosheets.

[0027] Figure 4The graph shows the HMF oxidation performance of the cobalt-nickel based amorphous sulfide CoNiS-A@NF electrocatalyst prepared in this invention at different potentials. At lower potentials (1.375 and 1.425 V vs. RHE), relatively high HMF conversion and FDCA Faradaic efficiency (FE) can be achieved, but the FDCA production rate is very low. When the potential is increased to 1.475 V vs. RHE, the HMF conversion is 98.5%, the FDCA yield is 97.1%, the FDCA FE is 96.9%, and the production rate reaches 380.0 μmol / cm³. -2 h -1 When the potential exceeds 1.475 V vs. RHE, although the production rate of FDCA continues to increase, the conversion rate of HMF and the FE of FDCA both begin to decrease due to the presence of the OER competing reaction. At 1.575 V vs. RHE, the FE drops to 86.6%. Therefore, the optimal electrolysis potential for the electrochemical oxidation of HMF by CoNiS-A@NF is 1.475 V vs. RHE.

[0028] Figure 5 The graph shows the HMF oxidation performance of the cobalt-nickel-based amorphous sulfide CoNiS-A@NF electrocatalyst prepared in this invention after 11 consecutive electrolysis experiments. The stability of the HMF electrochemical oxidation performance of the CoNiS-A@NF electrocatalyst was evaluated by applying a constant potential of 1.475 V vs. RHE. In these 11 cyclic electrolysis experiments, the HMF conversion (95.7%–98.5%), FDCA yield (93%–97.1%), and FE (92.8%–96.9%) fluctuated within a relatively small range, demonstrating that the cobalt-nickel-based amorphous sulfide CoNiS-A@NF electrocatalyst has good stability.

[0029] The present invention has been described above by way of example. It should be noted that any simple modifications, alterations or other equivalent substitutions that can be made by those skilled in the art without creative effort without departing from the core of the present invention fall within the protection scope of the present invention.

Claims

1. A method for preparing defect-rich cobalt-nickel-based amorphous sulfides and their application in the electrocatalytic oxidation of 5-hydroxymethylfurfural, characterized in that, Includes the following steps: (1) First, cut the NF to a size of 1cm × 3cm, using 3M L -1 The NF was ultrasonically cleaned with hydrochloric acid aqueous solution for 30 min to remove the oxide layer on the surface. Then, the NF was ultrasonically cleaned in anhydrous ethanol and deionized water for 10 min each. Finally, it was dried in a vacuum oven at 60℃ for 6 h to obtain clean NF. (2) Add the aqueous solution containing C4H6N2 to the Co(NO3)2·6H2O solution and stir magnetically to mix the solution evenly. Then, suspend a clean piece of NF (protected by PTFE tape on the top) 2 cm below the surface of the mixed solution and let it stand at room temperature for 4 h. After the reaction is complete, take out the sample, wash it with anhydrous ethanol, and dry it in a vacuum oven at 60℃ for 6 h. (3) The sample obtained in step (2) was added to an ethanol solution containing Ni(NO3)2·6H2O and etched for 1 hour under magnetic stirring. After the reaction was completed, the sample was taken out, washed with ultrapure water, and then dried in a vacuum oven at 60°C for 6 hours to obtain the sample cobalt-nickel based bimetallic hydroxide. (4) The sample obtained in step (3) was added to an ethanol solution containing Na2S·9H2O. After reacting for 24 hours, the sample was taken out, washed with anhydrous ethanol, and then dried in a vacuum oven at 60°C for 6 hours to obtain a defect-rich cobalt-nickel-based amorphous sulfide.

2. The preparation method according to claim 1, characterized in that, Amorphous nanosheet structures with lattice defects were obtained.

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