CN113555571B - MgPtC0.06H0.32Ti, N-C nano cuboid and preparation method and application thereof - Google Patents

Abstract

The invention discloses MgPtC_0.06H_0.32Nano cuboid of/Ti, N-C and preparation method thereofAnd the application, the nano cuboid is prepared by drying a dispersion liquid of titanium-containing metal organic framework material and chloroplatinic acid, covering the obtained solid powder with magnesium powder, and adding N₂The Pt-based catalyst is obtained by acid washing and drying after high-temperature heat treatment in the atmosphere, the content of the Pt element is only about 4.5 wt%, the preparation period is short, and the operation is simple. The material is used as an electrocatalyst for catalyzing the cathode oxygen reduction reaction of a fuel cell, has high ORR catalytic activity in acidic and alkaline solutions, particularly in the acidic solution, the catalytic activity is equivalent to commercial Pt/C, the methanol resistance and the cycling stability are superior to those of Pt/C, the catalytic activity is increased after 20000 circles of voltage cycling in a voltage range of 0.05-1.25V or 1.0-1.6V, the material is a novel ORR electrocatalyst which is low in price, high in activity, high in cycling stability, methanol resistance and applicable to wide pH, and has a remarkable application prospect in the fuel cell.

Description

MgPtC0.06H0.32Ti, N-C nano cuboid and preparation method and application thereof

Technical Field

The invention belongs to the technical field of nano material preparation and energy materials, and particularly relates to a methanol-resistant oxygen reduction reaction electrocatalyst with high activity and high cycle stability and suitable for both acid and alkali electrolytes and a preparation method thereof.

Background

With social development and technological progress, people have increasingly increased demands for energy, and development of green new energy to replace traditional fossil fuels becomes important content of development plans of various countries. The fuel cell is clean and efficient, has high conversion efficiency and quick low-temperature start, is very suitable for being used as an automobile power supply to replace gasoline, and is one of effective measures for reducing energy consumption and environmental pollution caused by gasoline combustion. However, the critical performance of fuel cell efficiency, lifetime, etc. is limited by the electrocatalyst, especially the cathode electrocatalyst. The cathode of the fuel cell undergoes an Oxygen Reduction Reaction (ORR), the reaction kinetics of which are slow, and the ORR reaction rate is typically accelerated using a platinum carbon (Pt/C) electrocatalyst. However, the reserves of Pt on the earth are low and are not uniformly distributed, and the Pt-containing mineral resources in China are poor, so that the price of the Pt/C electrocatalyst is high, and the cost of the fuel cell is too high to be applied in a large scale. In addition, when the Pt/C works in an oxygen-rich environment (especially in an acidic oxygen-rich solution) for a long time, the carbon matrix is gradually oxidized and corroded, so that the loaded Pt nano particles are agglomerated or fall off, the ORR catalytic activity of the Pt/C is seriously deteriorated, and the service life of the battery cannot meet the practical application. Further, when a liquid such as methanol or ethanol is used as a fuel for a fuel cell, the fuel permeating from the anode to the cathode of the cell through the exchange membrane also undergoes an oxidation reaction on the Pt nanoparticles, which leads to a decrease in the output voltage and a decrease in the output of the cell. Therefore, the development of an ORR electrocatalyst with low Pt loading, high activity, high stability, methanol resistance, and suitability for acid/alkali fuel cells has become an important goal for the development of new energy fields in various countries.

Disclosure of Invention

The invention aims to overcome the defects of high price, poor stability and weak methanol resistance of a commercial Pt/C electrocatalyst, and provides an oxygen reduction electrocatalyst MgPtC with low Pt element content, high activity, high cycle stability, methanol resistance and wide pH range_0.06H_0.32a/Ti, N-C nano cuboid, a preparation method and application of the material.

For the above purpose, MgPtC used in the present invention_0.06H_0.32the/Ti, N-C nano cuboid is prepared by the following method: ultrasonically dispersing titanium metal organic framework material in water or ethanol, adding chloroplatinic acid water solution, ultrasonically dispersing uniformly, drying the obtained dispersion liquid, uniformly spreading the dried solid powder in a porcelain boat, covering with magnesium powder, then placing the porcelain boat in a tube furnace, and putting the porcelain boat in a N-shaped furnace₂Carrying out heat treatment for 2-4 hours at 900-950 ℃ in the atmosphere, stirring and washing with hydrochloric acid after the heat treatment is finished, and carrying out centrifugal washing and drying on a solid product to obtain MgPtC_0.06H_0.32a/Ti, N-C nano cuboid.

In the above preparation method, the concentration of the titanium metal organic framework material in the obtained dispersion liquid is preferably controlled to be 0.008 to 0.012g/mL, and the concentration of the chloroplatinic acid is preferably controlled to be 0.001 to 0.002 mol/L.

The titanium metal organic framework material is obtained by carrying out solvothermal reaction on titanium isopropoxide and 2-aminoterephthalic acid in a mixed solution of methanol and N, N-dimethylformamide in a volume ratio of 1:1 at 140-160 ℃ for 15-18 hours according to a molar ratio of 1:2.

In the preparation method, the mass ratio of the solid powder to the magnesium powder is preferably controlled to be 1: 1.5-1: 2.5.

In the above production method, N is preferably used under a pressure of 0.025 to 0.04MPa₂Heating to 900-950 ℃ at a heating rate of 2-5 ℃/min in an atmosphere, and carrying out heat treatment for 2-4 hours.

In the preparation method, the concentration of the hydrochloric acid is 1-3 mol/L.

The invention MgPtC_0.06H_0.32the/Ti, N-C nano cuboid can be used as an electrocatalyst for catalyzing the cathode oxygen reduction reaction of the fuel cell.

Compared with the prior art, the invention has the following beneficial effects:

the invention prepares the MgPtC with the Pt element content of only about 4.5wt percent through simple dipping, high-temperature heat treatment and subsequent acid washing_0.06H_0.32the/Ti, N-C nano cuboid has short preparation period and simple operation. The material is used as an electrocatalyst for catalyzing the cathode oxygen reduction reaction of a fuel cell, has high ORR catalytic activity in acidic and alkaline solutions, particularly in the acidic solution, the catalytic activity is equivalent to commercial Pt/C, and the methanol resistance and the cycling stability are superior to those of Pt/C, and the catalytic activity is improved after the circulation of 20000 circles in a voltage interval of 0.05-1.25V or 1.0-1.6V.

Drawings

FIG. 1 shows MgPtC prepared in examples 1, 3 and 4_0.06H_0.32XRD pattern of/Ti, N-C nano cuboid.

FIG. 2 is MgPtC prepared in example 1_0.06H_0.32TEM image of/Ti, N-C nano cuboid.

FIG. 3 is MgPtC prepared in example 1_0.06H_0.32N of/Ti, N-C nano cuboid₂Isothermal physical adsorption/desorption curves.

FIG. 4 is MgPtC prepared in example 1_0.06H_0.32The aperture distribution diagram of the/Ti, N-C nano cuboid.

FIG. 5 is MgPtC prepared in example 1_0.06H_0.32XPS spectrum of/Ti, N-C nano cuboid.

FIG. 6Is MgPtC prepared in example 1_0.06H_0.32Raman spectrum of the/Ti, N-C nano cuboid.

FIG. 7 is MgPtC prepared in example 1_0.06H_0.32Linear cyclic voltammetry (LSV) curves of/Ti, N-C nano-cuboids and commercial Pt/C (20 wt%) against ORR in basic (0.1mo1/L KOH) solution.

FIG. 8 is MgPtC prepared in example 1_0.06H_0.32Nano cuboid of/Ti, N-C and commercial Pt/C (20 wt%) in acidity (0.1mo1/L HClO)₄) LSV curve in solution against ORR.

FIG. 9 is MgPtC prepared in example 1_0.06H_0.32The nano cuboid of/Ti, N-C and commercial Pt/C (20 wt%) are respectively in acidity (0.5mo1/L H)₂SO₄) Solution and acidity with 1mo1/L methanol (0.5mo1/L H)₂SO₄) Cyclic voltammogram in solution.

FIG. 10 is MgPtC prepared in example 1_0.06H_0.32Nano cuboid of/Ti, N-C and commercial Pt/C (20 wt%) in acidity (0.1mo1/L HClO)₄) Chronoamperometric profile at 0.8V vs. rhe in solution.

FIG. 11 is MgPtC prepared in example 1_0.06H_0.32Nano cuboid of/Ti, N-C and commercial Pt/C (20 wt%) in acidity (0.1mo1/L HClO)₄) LSC curve of ORR before and after 0.05-1.25V (RHE) voltage range 20000 CV cycles in the solution.

FIG. 12 is MgPtC prepared in example 1_0.06H_0.32Nano cuboid of/Ti, N-C and commercial Pt/C (20 wt%) in acidity (0.1mo1/L HClO)₄) LSV curve of ORR before and after 1-1.6V (RHE) high voltage range 20000 CV cycles in solution.

FIG. 13 is MgPtC prepared in example 2_0.06H_0.32The nano cuboid of/Ti, N-C is in acidity (0.1mo1/L HClO)₄) LSV curves for ORR in solution and alkaline (0.1mo1/L KOH) solutions.

FIG. 14 is MgPtC prepared in example 3_0.06H_0.32The nano cuboid of/Ti, N-C is in acidity (0.1mo1/L HClO)₄) LSV curves for ORR in solution and alkaline (0.1mo1/L KOH) solutions.

FIG. 15 is MgPtC prepared in example 4_0.06H_0.32The nano cuboid of/Ti, N-C is in acidity (0.1mo1/L HClO)₄) LSV curves for ORR in solution and alkaline (0.1mo1/L KOH) solutions.

FIG. 16 is MgPtC prepared in example 5_0.06H_0.32The nano cuboid of/Ti, N-C is in acidity (0.1mo1/L HClO)₄) LSV curves for ORR in solution and alkaline (0.1mo1/L KOH) solutions.

Detailed Description

The invention is described in further detail below with reference to the figures and examples, but the scope of the invention as claimed is not limited to these examples.

The Ti-MOFs used in the following examples were synthesized according to the literature methods (Wu, Y., Huang, Z., Jiang, H., et al, facility Synthesis of Universal Metal Nanoparticles from Metal-Organic Frameworks by Laser Metal Applied Materials & interfaces, 2019,11, (47), 44573-: 0.853g (3mmol) of titanium isopropoxide and 1.087g (6mmol) of 2-aminoterephthalic acid were added to 50mL of a mixed solution of methanol and N, N-Dimethylformamide (DMF) in a volume ratio of 1:1 in sequence, stirred until dissolved, transferred to a 150mL polytetrafluoroethylene kettle, and heated at 150 ℃ for 16 h. And centrifuging to obtain a solid product, washing the solid product with DMF and methanol respectively for 3 times, and performing vacuum drying at 150 ℃ for 12 hours to obtain the dried Ti-MOF.

Example 1

Adding 0.1g of Ti-MOF into 10mL of ethanol, performing ultrasonic dispersion for 30min, adding 640 mu L of 19.3mmol/L chloroplatinic acid aqueous solution, performing ultrasonic mixing for 60min, and drying in an oven at 60 ℃. Uniformly spreading the dried solid powder in a porcelain boat, spreading a layer of magnesium powder on the upper layer of the porcelain boat, controlling the mass ratio of the solid powder to the magnesium powder to be 1:2, then placing the porcelain boat in a tube furnace, and putting the porcelain boat in a furnace N₂Under the atmosphere, the pressure in the tube is kept at 0.03MPa, the temperature is raised to 900 ℃ at the heating rate of 3 ℃/min, and the temperature is kept for 2 h. Stirring and washing the obtained sample in 2mol/L hydrochloric acid for 2h, centrifugally separating a solid product, washing the solid product to be neutral by using water, and drying the solid product at 80 ℃ to obtain MgPtC_0.06H_0.32a/Ti, N-C nano cuboid.

The resulting product was obtained using Smart Lab (9)The crystal structure, morphology, specific surface area, pore structure, pore diameter, pore volume and element valence of the X-ray diffractometer (Nippon chemical company), Tecnai G2F 20 transmission electron microscope, full-automatic specific surface area and micropore physisorption instrument (ASAP2460, American Michkok company), XPS and Raman spectrometer are characterized, and the results are shown in FIGS. 1-6. In fig. 1, distinct diffraction peaks are seen at 25.38, 30.18, and 39.765 ° 2 θ, corresponding to MgPtC, respectively_0.06H_0.32The (001), (100) and (101) planes of (A), and MgPtC_0.06H_0.32Is consistent with standard PDF card, indicating that the product contains crystalline MgPtC_0.06H_0.32. As can be seen from FIG. 2, the obtained product is a nano cuboid, and the particle size range is 100-300 nm. The nitrogen physical adsorption-desorption curve of FIG. 3 shows a steep rising trend at a relative pressure of less than 0.01 and a hysteresis loop at a relative pressure of 0.4 or more, indicating that the product has a large number of micropores and mesopores, and the specific surface area of the obtained product is 584m calculated by a Density Functional (DFT) method²g^-1. It can also be seen from the pore size distribution diagram of fig. 4 that the product has a microporous and mesoporous structure. The XPS survey of FIG. 5 shows characteristic peaks for C, N, O, Mg, Ti, Pt, Mg being residual small amounts of MgCl₂There is no effect on ORR performance. Meanwhile, the raman spectrum of fig. 6 confirms the presence of TiC_yO_z. Comprehensive characterization data show that the main body of the nano cuboid is Ti and N element doped low-graphitization carbon, wherein Ti is connected into a carbon skeleton through Ti-O, Ti-N and Ti-C bonds, and crystallized MgPtC_0.06H_0.32Uniformly embedded in the carbon nano cuboid.

Hg/Hg with carbon rod as counter electrode₂Cl₂The electrode is a reference electrode coated with MgPtC_0.06H_0.32The glassy carbon electrode of the/Ti, N-C nano cuboid is taken as a working electrode to form a three-electrode system. Respectively in 0.1mo1/L KOH solution and 0.1mo1/L HClO₄The ORR catalytic activity was measured in solution. As can be seen from FIGS. 7 and 8, MgPtC is present in acidic and alkaline solutions_0.06H_0.32ORR catalytic activity of/Ti, N-C nano cuboid is equivalent to commercial Pt/C (20 wt%). FIG. 9 shows the reaction mixture in the acidic state (0.5mo1/L H)₂SO₄) And contains 1mo1/LAcidity of methanol (0.5mo1/L H)₂SO₄) In electrolyte, MgPtC_0.06H_0.32CV curves of the catalytic activity of the/Ti, N-C nano cuboid and the commercial Pt/C (20 wt%) to the methanol show that the commercial Pt/C (20 wt%) CV curve has obvious methanol oxidation peaks, which indicates that the methanol resistance is poor; and MgPtC_0.06H_0.32The CV curve of the/Ti, N-C nano cuboid has no methanol oxidation peak, which shows that the methanol resistance is excellent. FIG. 10 shows the reaction conditions in the acidic state (0.1mo1/L HClO₄) Chronoamperometric curve of ORR catalytic process measured in solution at 0.5V vs. RHE voltage, for commercial Pt/C (20 wt%), current density was measured from initial-2.96 mA/cm over time²It became-2.17 mA/cm²The current retention rate (73%) was not good; and MgPtC_0.06H_0.32The current retention rate of the/Ti, N-C nano cuboid is 89%, and the long-time discharge stability is better. FIG. 11 shows the reaction mixture in acidic condition (0.1mo1/L HClO₄) LSV curve graph of ORR before and after 20000 CV cycles at sweep rate of 50mV/s in the voltage range of 0.05-1.25V (RHE), as can be seen from the graph, after 20000 cycles, the half-wave potential of commercial Pt/C (20 wt%) is shifted negatively by 110mV, which means that ORR catalytic performance is deteriorated; and MgPtC_0.06H_0.32The half-wave potential of the/Ti, N-C nano cuboid is shifted by 10mV, which shows that the ORR catalytic performance becomes more excellent after being circulated for 20000 times. FIG. 12 shows the reaction mixture in acidic (0.1mo1/L HClO)₄) LSV curve of ORR before and after 20000 CV cycles at a sweep rate of 500mV/s in the range of 1-1.6V (RHE) of high potential in the solution. Under the condition of high potential, the medium carbon carrier of commercial Pt/C (20 wt%) can generate oxidation corrosion, so that the loaded Pt nano particles are agglomerated and fall off, the ORR catalytic activity is reduced, the half-wave potential is shifted negatively by 40mV, and MgPtC_0.06H_0.32After the/Ti, N-C nano cuboid is circulated for 20000 times, the half-wave potential is shifted by 10mV, which shows that the nano cuboid has excellent corrosion resistance, the ORR catalytic performance is not influenced by the working voltage range, and the nano cuboid has better practical application prospect compared with commercial Pt/C (20 wt%).

Example 2

Adding 0.1g Ti-MOF into 10mL ethanol, and ultrasonically dispersing for 30min640 mul of 19.3mmol/L chloroplatinic acid aqueous solution is added, ultrasonic mixing is carried out for 60min, and then drying is carried out in an oven at 60 ℃. Uniformly spreading the dried solid powder in a porcelain boat, spreading a layer of magnesium powder on the upper layer of the porcelain boat, controlling the mass ratio of the solid powder to the magnesium powder to be 1:1.5, then placing the porcelain boat in a tubular furnace, and putting the porcelain boat in a N furnace₂Under the atmosphere, the pressure in the tube is kept at 0.03MPa, the temperature is increased to 900 ℃ at the heating rate of 3 ℃/min, and the temperature is kept for 2 h. Stirring and washing the obtained sample in 2mol/L hydrochloric acid for 2h, centrifugally separating a solid product, washing the solid product to be neutral by using water, and drying the solid product at 80 ℃ to obtain MgPtC_0.06H_0.32a/Ti, N-C nano cuboid. The LSV curves of the resulting samples against ORR in acidic and basic solutions are shown in FIG. 13. As can be seen, it has good ORR activity in both acidic and alkaline electrolytes.

Example 3

Adding 0.1g of Ti-MOF into 10mL of ethanol, performing ultrasonic dispersion for 30min, adding 640 mu L of 19.3mmol/L chloroplatinic acid aqueous solution, performing ultrasonic mixing for 60min, and drying in an oven at 60 ℃. Uniformly spreading the dried solid powder in a porcelain boat, spreading a layer of magnesium powder on the upper layer of the porcelain boat, controlling the mass ratio of the solid powder to the magnesium powder to be 1:2.5, then placing the porcelain boat in a tubular furnace, and putting the porcelain boat in a N furnace₂Under the atmosphere, the pressure in the tube is kept at 0.03MPa, the temperature is increased to 900 ℃ at the heating rate of 3 ℃/min, and the temperature is kept for 2 h. Stirring and washing the obtained sample in 2mol/L hydrochloric acid for 2h, centrifugally separating a solid product, washing the solid product to be neutral by using water, and drying the solid product at 80 ℃ to obtain MgPtC_0.06H_0.32a/Ti, N-C nano cuboid. The LSV curves of the resulting samples against ORR in acidic and basic solutions are shown in FIG. 14. As can be seen, it has good ORR activity in both acidic and alkaline electrolytes.

Example 4

Adding 0.1g of Ti-MOF into 10mL of water, performing ultrasonic dispersion for 30min, adding 640 mu L of 19.3mmol/L chloroplatinic acid aqueous solution, performing ultrasonic mixing for 60min, and drying in an oven at 60 ℃. Uniformly spreading the dried solid powder in a porcelain boat, spreading a layer of magnesium powder on the upper layer of the porcelain boat, controlling the mass ratio of the solid powder to the magnesium powder to be 1:2, then placing the porcelain boat in a tube furnace, and putting the porcelain boat in a furnace N₂Under the atmosphere, the pressure in the tube is kept at 0.03MPa, the temperature is increased to 900 ℃ at the heating rate of 3 ℃/min, and the temperature is kept for 2 h. The obtained sampleStirring and washing in 2mol/L hydrochloric acid for 2h, centrifugally separating a solid product, washing to be neutral by using water, and drying at 80 ℃ to obtain MgPtC_0.06H_0.32a/Ti, N-C nano cuboid. The LSV curves of the resulting samples against ORR in acidic and basic solutions are shown in FIG. 15. As can be seen, it has good ORR activity in both acidic and alkaline electrolytes.

Example 5

Adding 0.1g of Ti-MOF into 10mL of ethanol, performing ultrasonic dispersion for 30min, adding 640 mu L of 19.3mmol/L chloroplatinic acid aqueous solution, performing ultrasonic mixing for 60min, and drying in an oven at 60 ℃. Uniformly spreading the dried solid powder in a porcelain boat, spreading a layer of magnesium powder on the upper layer of the porcelain boat, controlling the mass ratio of the solid powder to the magnesium powder to be 1:2.5, then placing the porcelain boat in a tubular furnace, and putting the porcelain boat in a N furnace₂Under the atmosphere, the pressure in the tube is kept at 0.03MPa, the temperature is raised to 900 ℃ at the heating rate of 3 ℃/min, and the temperature is kept for 3 h. Stirring and washing the obtained sample in 2mol/L hydrochloric acid for 2h, centrifugally separating a solid product, washing the solid product to be neutral by using water, and drying the solid product at 80 ℃ to obtain MgPtC_0.06H_0.32a/Ti, N-C nano cuboid. The LSV curves of the resulting samples against ORR in acidic and basic solutions are shown in FIG. 16. As can be seen, it has good ORR activity in both acidic and alkaline electrolytes.

Claims (7)

1. MgPtC_0.06H_0.32The preparation method of the/Ti, N-C nano cuboid is characterized by comprising the following steps: ultrasonically dispersing titanium metal organic framework material in water or ethanol, adding chloroplatinic acid water solution, ultrasonically dispersing uniformly, drying the obtained dispersion liquid, uniformly spreading the dried solid powder in a porcelain boat, covering with magnesium powder, then placing the porcelain boat in a tube furnace, and adding N₂Carrying out heat treatment for 2-4 hours at 900-950 ℃ in the atmosphere, stirring and washing with hydrochloric acid after the heat treatment is finished, and carrying out centrifugal washing and drying on a solid product to obtain MgPtC_0.06H_0.32A nano cuboid of Ti, N-C;

the titanium metal organic framework material is obtained by carrying out solvothermal reaction on titanium isopropoxide and 2-amino terephthalic acid in a mixed solution of methanol and N, N-dimethylformamide in a volume ratio of 1:1 at 140-160 ℃ for 15-18 hours according to a molar ratio of 1:2.

2. The MgPtC of claim 1_0.06H_0.32The preparation method of the/Ti, N-C nano cuboid is characterized by comprising the following steps: the concentration of the titanium metal organic framework material in the obtained dispersion liquid is controlled to be 0.008-0.012 g/mL, and the concentration of the chloroplatinic acid is controlled to be 0.001-0.002 mol/L.

3. The MgPtC of claim 1_0.06H_0.32The preparation method of the/Ti, N-C nano cuboid is characterized by comprising the following steps: the mass ratio of the solid powder to the magnesium powder is controlled to be 1: 1.5-1: 2.5.

4. The MgPtC of claim 1_0.06H_0.32The preparation method of the/Ti, N-C nano cuboid is characterized by comprising the following steps: n under a pressure of 0.025 to 0.04MPa₂Heating to 900-950 ℃ at a heating rate of 2-5 ℃/min in an atmosphere, and carrying out heat treatment for 2-4 hours.

5. The MgPtC of claim 1_0.06H_0.32The preparation method of the/Ti, N-C nano cuboid is characterized by comprising the following steps: the concentration of the hydrochloric acid is 1-3 mol/L.

6. MgPtC prepared by the process of claim 1_0.06H_0.32a/Ti, N-C nano cuboid.

7. The MgPtC of claim 6_0.06H_0.32The application of the/Ti, N-C nano cuboid as an electrocatalyst in catalyzing the cathode oxygen reduction reaction of a fuel cell.

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