Manganese-doped nickel selenide nanoparticles, preparation method thereof and application of manganese-doped nickel selenide nanoparticles in methanol oxidation reaction

Abstract

The invention discloses manganese-doped nickel selenide nanoparticles, a preparation method thereof and application of the manganese-doped nickel selenide nanoparticles in methanol electrocatalytic oxidation. Firstly, a series of Ni3Se4-x% Mn (x = 5, 10 or 15) flaky nanoparticles are prepared through a hydrothermal method, the particle size is 18-39 nm, and the material has excellent performance in methanol oxidation reaction and is superior to pure-phase Ni3Se4. When the doping amount of Mn is 10%, the methanol oxidation performance is the best, in a 1M KOH + 1M methanol electrolyte, the current density reaches about 190 mA cm <-2 > when the voltage is 1.6 V, the Faraday efficiency is close to 100%, the current density is still kept at 123 mA cm <-2 > after being tested for 18 hours, and the stability is good. In general, by introducing manganese atoms to regulate and control the spinning state and the electronic structure, the catalytic performance is improved, the preparation method is simple, the cost is low, and certain application prospects are achieved in the fields of hydrogen production through water electrolysis coupling, small organic molecule electrocatalytic oxidation and the like.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of electrocatalytic materials, and particularly relates to a manganese-doped nickel selenide nanoparticle, a preparation method thereof, and application of the nanoparticle in a methanol oxidation reaction. BACKGROUND

[0002] The reaction of oxidizing methanol into formic acid (Methanol Oxidation Reaction, MOR) provides a promising alternative to the anodic oxygen evolution reaction (Oxygen Evolution Reaction, OER) of water electrolysis. The reaction has many advantages such as high energy efficiency, good selectivity, operation at normal temperature and pressure, and utilization of renewable electricity, and can be combined with an electro-reduction reaction, which has important application value in industry (Nat Commun, 2020, 11, 4647). However, traditional MOR mostly relies on noble metal catalysts, which seriously limits its popularization and application in large-scale industry.

[0003] To break this bottleneck, researchers have gradually turned to exploring low-cost catalysts based on 3d transition metals (ACS Energy Letters, 2024 9(3), 853-879). Among them, nickel-based materials exhibit excellent performance under alkaline conditions, and the NiOOH species formed on their surface is considered to be the real active species in MOR (J. Am. Chem. Soc. 2024, 146, 7, 4830-4841). Current research is mainly devoted to improving the overall catalytic performance by increasing the number of active sites and optimizing their intrinsic activity, and the regulation of electronic structure is a key means.

[0004] In recent years, spin state is considered to be a key but often neglected parameter in electrocatalysis. The spin state of the metal center affects the bonding strength with the ligand, and then affects the adsorption behavior of the reaction intermediate, ultimately determines the efficiency of the overall catalytic reaction. Although there is much evidence that spin state has a key influence on various electrochemical reactions, research on how metal cation doping regulates the electronic structure and spin state of MOR catalysts is still relatively scarce.

[0005] Therefore, the application provides a high-efficiency and low-cost catalyst for methanol oxidation reaction, which improves the catalytic performance by regulating the electronic structure and spin state of the catalyst.

[0006] TECHNICAL SCHEME

[0007] A manganese-doped nickel selenide nanoparticle has a chemical formula of Ni3Se4-x%Mn, wherein x is 5, 10 or 15, and the nanoparticle has a sheet-like morphology and a particle size of 18 nm to 39 nm. The preparation method of the manganese-doped nickel selenide nanoparticle comprises the following steps:

[0008] (1) Preparation of chemical reagents: nickel nitrate hexahydrate (Ni(NO3)2·6H2O, 98%), manganese nitrate solution (Mn(NO3)2, 50%), potassium hydroxide (KOH, 99%), selenium powder (Se, 99%, 100 mesh), hydrazine hydrate (N2H4·H2O, 98%), carbon black, and 10% Nafion solution.

[0009] (2) Preparation of aqueous metal salt solution: Ni(NO3)2·6H2O and Mn(NO3)2 were used as precursors to prepare an aqueous metal salt solution with a molar ratio of Ni to Mn of 100:0, 95:5, 90:10, or 85:15, and a total metal ion molar number of 3.3 mmol, which was dissolved in deionized water.

[0010] (3) Preparation of selenium-containing solution: 4.4 mmol of Se powder was dissolved in 10 mL of hydrazine hydrate solution.

[0011] (4) Mixing and ultrasonicating: the aqueous metal salt solution obtained in step 2 was mixed with the selenium-containing solution obtained in step 3, and ultrasonicated for 30 minutes.

[0012] (5) Hydrothermal reaction: the mixed solution was transferred to a 50 mL polytetrafluoroethylene-lined stainless steel high-pressure reaction kettle, and hydrothermally reacted at 180°C for 16 hours.

[0013] (6) Washing and drying: the precipitate obtained by reaction was washed with deionized water and ethanol (centrifuged 4 times), and then placed in a 60°C vacuum drying box for drying for 24 hours to obtain manganese-doped nickel selenide nanoparticles in the form of black powder.

[0014] For comparison, pure-phase Ni3Se4 nanoparticles were prepared using the above steps without adding the Mn precursor.

[0015] The manganese-doped nickel selenide nanoparticles were used as catalysts for methanol oxidation reaction. In a 1M KOH+1M methanol electrolyte, the MOR current density of the catalyst at 1.6V voltage was about 190mA cm -2 , and the Faraday efficiency was close to 100%.

[0016] Advantages

[0017] The present application significantly improves the catalytic performance of MOR by introducing manganese atoms with unsaturated t2g orbitals into Ni3Se4. The manganese-doped nickel selenide nanoparticles prepared as catalysts have high current density and high Faraday efficiency, with a current density of about 190mA cm -2The catalyst exhibits a Faraday efficiency close to 100% and excellent stability, maintaining a high current density even during continuous 18-hour testing, far exceeding most reported Ni-based catalysts. Its preparation method is simple and low-cost, providing a strong theoretical and experimental basis for developing high-performance, low-cost alcohol electrooxidation catalysts. It also shows broad application prospects in fuel cells, green formic acid synthesis, and clean energy conversion. Attached Figure Description

[0018] Figure 1 Schematic diagram of the synthesis process of Ni3Se4–x%Mn particles.

[0019] Figure 2 XRD patterns of Ni3Se4 with different Mn doping ratios – x%Mn and pure Ni3Se4.

[0020] Figure 3 TEM images and particle size distributions of samples (a) Ni3Se4, (b) Ni3Se4–5% Mn, (c) Ni3Se4–10% Mn, and (d) Ni3Se4–15% Mn.

[0021] Figure 4 (a) Elemental distribution map, (b) EDS line scan and (c) HRTEM image of Ni3Se4–10% Mn sample.

[0022] Figure 5 Electrochemical performance of Ni3Se4 with different Mn doping ratios and pure Ni3Se4 in (a) electrolytes containing methanol and (b) electrolytes without methanol.

[0023] Figure 6 (a) CA curves of Ni3Se4–10%Mn sample at different potentials; (b) corresponding IC spectra; (c) FE at different potentials.

[0024] Figure 7 (a) 18-hour CA test of Ni3Se4 with different Mn doping ratios and pure Ni3Se4; (b) IC curve; (c) comparison of formic acid yield with FE. Detailed Implementation

[0025] Example 1: Preparation of Ni3Se4

[0026] 1. Weigh 3.3 mmol of Ni(NO3)2·6H2O, dissolve it in an appropriate amount of deionized water, and prepare an aqueous solution of the metal salt.

[0027] 2. Dissolve 4.4 mmol of Se powder in 10 mL of hydrazine hydrate solution to obtain a selenium-containing solution.

[0028] 3. Mix the aqueous solution of the metal salt with the selenium-containing solution and sonicate for 30 minutes.

[0029] 4. Transfer the mixture to a 50mL polytetrafluoroethylene-lined stainless steel high-pressure reactor and hydrothermally react at 180℃ for 16 hours.

[0030] 5. After the reaction was completed, the precipitate was washed with deionized water and ethanol (centrifuged 4 times), and then dried in a vacuum drying oven at 60℃ for 24 hours to obtain Ni3Se4 nanoparticles.

[0031] Example 2: Preparation of Ni3Se4-5%Mn

[0032] 1. Weigh 3.135 mmol of Ni(NO3)2·6H2O and 0.165 mmol of Mn(NO3)2, dissolve them in an appropriate amount of deionized water to make the molar ratio of Ni to Mn 95:5 and the total number of metal ions 3.3 mmol, and prepare an aqueous solution of metal salt.

[0033] 2. Prepare a selenium-containing solution in the same manner as step 2 of Example 1.

[0034] 3. Following steps 3 to 5 of Example 1, Ni3Se4–5%Mn nanoparticles were obtained.

[0035] Example 3: Preparation of Ni3Se4-10%Mn

[0036] 1. Weigh 2.97 mmol of Ni(NO3)2·6H2O and 0.33 mmol of Mn(NO3)2, dissolve them in an appropriate amount of deionized water to make the molar ratio of Ni to Mn 90:10 and the total number of metal ions 3.3 mmol, and prepare an aqueous solution of metal salt.

[0037] 2. Prepare a selenium-containing solution in the same manner as step 2 of Example 1.

[0038] 3. Following steps 3 to 5 of Example 1, Ni3Se4–10%Mn nanoparticles were obtained.

[0039] Example 4: Preparation of Ni3Se4-15%Mn

[0040] 1. Weigh out 2.805 mmol of Ni(NO3)2·6H2O and 0.495 mmol of Mn.

[0041] (NO3)2 is dissolved in an appropriate amount of deionized water to make the molar ratio of Ni to Mn 85:15 and the total number of metal ions 3.3 mmol, thus preparing an aqueous solution of the metal salt.

[0042] 2. Prepare a selenium-containing solution in the same manner as step 2 of Example 1.

[0043] 3. Following steps 3 to 5 of Example 1, Ni3Se4–15%Mn nanoparticles were obtained.

[0044] Characterization and performance testing of catalysts

[0045] 1. Crystal Structure Analysis: The crystal structure of the samples prepared in each embodiment was analyzed by X-ray diffraction (XRD). The scanning range was 2θ = 15–75°, and the scanning speed was 10° / min. The results are as follows: Figure 2 As shown, the sample exhibits distinct diffraction peaks at 33.3°, 45.1°, 50.8°, 60.7°, and 61.7°, corresponding to the (–112), (–314), (310), (–716), and (–422) crystal planes of Ni3Se4 (JCPDS card number: 97-004-2558), respectively. No Mn-related impurities or other Ni–Se phases were observed, indicating that the introduction of Mn did not alter the crystal structure of Ni3Se4.

[0046] 2. Morphology and Elemental Analysis: Morphology was analyzed using a Hitachi SU-70 scanning electron microscope (SEM), and elemental distribution and content were determined using energy dispersive spectroscopy (EDS). The detailed structure of the samples was further observed using a JEM-F200 transmission electron microscope (TEM). Results are as follows: Figure 3 As shown, the resulting particles have a plate-like morphology. After Mn doping, the particle size gradually increases from about 18±5 nm in pure Ni3Se4 to 39±5 nm in Ni3Se4–15% Mn. Figure 4 The sample indicates that Ni, Mn, and Se elements are uniformly distributed in the sample. High-resolution transmission electron microscopy (HRTEM) shows that the Ni3Se4–10% Mn sample has a monoclinic crystal system. Mn doping reduces the (1-1-2) interplanar spacing, indicating that the substitution effect of Mn leads to lattice shrinkage.

[0047] 3. Electrochemical Performance Testing: Electrochemical tests were conducted using a CorrTest (CS2350H) three-electrode system under open-environment conditions at room temperature. The working electrode was a prepared glassy carbon electrode, the counter electrode was a platinum wire, and the reference electrode was Hg / HgO. All tests were performed in 1M KOH electrolyte, with some experiments supplemented with 1M methanol. Catalytic activity was evaluated using cyclic voltammetry (CV) and chronoamperometry (CA). The results are as follows: Figure 5 As shown, in a 1M KOH + 1M methanol electrolyte, the current density of undoped Ni3Se4 at 1.6V is 140 mA cm⁻¹. -2 The Ni3Se4–5% Mn, –10% Mn, and –15% Mn samples reached 176, 190, and 156 mA cm⁻¹, respectively. -2 In summary, a 10% Mn doping ratio resulted in the best catalytic activity.

[0048] 4. Faraday efficiency (FE) test: Chronoamperometry (CA) tests were performed on Ni3Se4–10% Mn samples at different voltages (1.3–1.8 V). After 1 hour of testing, the electrolyte was extracted, and the formic acid yield was determined by ion chromatography (IC). The Faraday efficiency was calculated. Results are as follows: Figure 6 As shown, FE peaks at 1.6V, reaching nearly 100%, and then decreases, indicating that the OER reaction competition intensifies thereafter, inhibiting formic acid formation.

[0049] 5. Stability Test: The electrodes prepared in each embodiment were subjected to an 18-hour CA test at 1.6V. The results are as follows. Figure 7 As shown, Ni3Se4–10% Mn still maintains 123 mA cm⁻¹ after 18 hours. -2 The initial current density decreased by 36.4% compared to the initial value, and its overall performance was the best. It generated 4.63 mmol of formic acid within 18 hours, with an average FE of 93.2%, which was better than other doping ratio samples and pure Ni3Se4.

Claims

1. A wet chemical synthesis method of manganese doped nickel selenide nanoparticles with high methanol oxidation activity, characterized in that, Ni3Se4-x%Mn, wherein x is 5, 10 or 15, the nanoparticles have a sheet-like morphology and a particle size of 18-39 nm.

2. The method for preparing manganese-doped nickel selenide nanoparticles as described in claim 1, characterized in that, The method comprises the following steps: (1) using Ni(NO3)2·6H2O and Mn(NO3)2 as precursors, the molar ratio of Ni to Mn is 95:5, 90:10 or 85:15, the total number of metal ions is 3.3 mmol, and the metal salt aqueous solution is prepared by dissolving in deionized water; (2) dissolving 4.4 mmol of Se powder in 10 mL of hydrazine hydrate solution to obtain a selenium-containing solution; (3) mixing the metal salt aqueous solution with the selenium-containing solution and ultrasonicating for 30 minutes; (4) transferring the mixed solution into a 50 mL polytetrafluoroethylene-lined stainless steel high-pressure reaction kettle, and hydrothermally reacting at 180℃ for 16 hours; (5) drying the precipitate obtained by reaction in a 60℃ vacuum drying box for 24 hours after washing with deionized water and ethanol and centrifugation to obtain the manganese-doped nickel selenide nanoparticles.

3. Use of the manganese-doped nickel selenide nanoparticles according to claim 1 in the oxidation of methanol, characterized in that, The electrocatalytic performance is higher than that of the pure Ni3Se4 comparative sample, and when the doping amount of Mn is 10%, the sample has the optimal methanol oxidation performance. In 1M KOH+1M methanol electrolyte, the MOR current density of the catalyst at 1.6V voltage is 190mA cm -2 , and the faradic efficiency is about 100%.

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