A simple and environment-friendly preparation method of microcrystalline cellulose-based electrocatalytic oxygen evolution material

Abstract

The application discloses a simple and environment-friendly preparation method of a microcrystalline cellulose-based electrocatalytic oxygen evolution material, and belongs to the technical field of catalysts. The application aims at solving the problems of the prior art, such as the difficulty in forming a nano-scale structure for a transition metal-based OER catalyst, the disadvantage of the catalyst in high efficiency and stability, and the problems of high production cost, complex process, strict experimental conditions and environmental pollution. The method comprises the following steps: firstly, metal precursors and coordination precursors are added into water to be dissolved and dispersed, then microcrystalline cellulose is added to be stirred uniformly, and finally, drying and grinding are performed; secondly, solid powder is calcined at high temperature; and finally, cooling is performed to room temperature. The application is used for the preparation of the simple and environment-friendly microcrystalline cellulose-based electrocatalytic oxygen evolution material.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of catalysts. BACKGROUND

[0002] Oxygen evolution reaction (OER) plays a crucial role in sustainable energy storage and conversion, including water electrolysis for hydrogen production, metal-air batteries, and carbon dioxide electroreduction. Due to the slow kinetics of four proton-coupled electron transfer involved in oxygen evolution reaction, the energy conversion efficiency of the above devices is low. Although noble metal-based (such as Ir and Ru) materials are currently the benchmark for OER electrocatalysts, their low reserves in nature and high prices make it difficult to achieve large-scale applications.

[0003] Compared with noble metals, transition metals have the advantages of abundant natural reserves and low cost. At present, many studies have synthesized transition metal-based OER catalysts with performance not inferior to noble metals by using strategies such as structure size design and coordination environment regulation. The activity and stability of OER catalysts are closely related to the structure, and the nanoscale structure means more active sites, and some studies have also shown that the nanoscale structure is also beneficial to reducing side reactions and improving the stability of the catalyst. On the one hand, the transition metals and their compounds synthesized by traditional high-temperature solid-phase method are difficult to form nanoscale structure by physical grinding method, which is not conducive to the high efficiency and stability of the catalyst. On the other hand, most of the existing nanoscale catalyst synthesis methods have problems such as high production cost, complex process, harsh experimental conditions, and environmental pollution, which are difficult to realize large-scale production. Therefore, it is very urgent to design a simple and environmentally friendly preparation method of microcrystalline cellulose-based electrocatalytic oxygen evolution material. SUMMARY

[0004] The present application aims to solve the problems of existing transition metal-based OER catalysts that are difficult to form nanoscale structure, which is not conducive to the high efficiency and stability of the catalyst, and the problems of high production cost, complex process, harsh experimental conditions, and environmental pollution, and further provides a simple and environmentally friendly preparation method of microcrystalline cellulose-based electrocatalytic oxygen evolution material.

[0005] A simple and environmentally friendly preparation method of microcrystalline cellulose-based electrocatalytic oxygen evolution material, which is carried out according to the following steps:

[0006] I. Dissolve and disperse the metal precursor and the coordination precursor in water, then add microcrystalline cellulose and stir uniformly, and finally dry and grind uniformly to obtain a solid powder;

[0007] The coordination precursor is one or a combination of several of thiourea, sodium hypophosphite, urea, and ammonium chloride;

[0008] II. Under the protection of the gas, the solid powder is high-temperature calcined, and finally cooled to room temperature, so that the preparation method of the simple and environment-friendly microcrystalline cellulose-based electrocatalytic oxygen evolution material is completed.

[0009] The beneficial effects of the present application are:

[0010] 1. In the preparation method, the microcrystalline cellulose has the advantages of small size, large specific area and high crystallinity, and the surface also contains a large number of hydroxyl groups, which is beneficial to realize the surface adsorption of a large number of transition metal ions. The microcrystalline cellulose has high crystallinity and order, which is beneficial to form a graphitized structure in the high-temperature calcination process, thereby improving the conductivity of the catalyst. The biomass carbon material formed also has a certain spatial confinement effect, which is beneficial to alleviate the migration and agglomeration of metal particles, and form smaller particles. The production process of microcrystalline cellulose is mature, which is beneficial to realize large-scale production.

[0011] 2. The electrocatalyst prepared in the present application is specifically a heteroatom-doped carbon material surface loaded with transition metal compound nanoparticles, which has good OER activity and stability.

[0012] 3. The raw material cost of the method is low, and the industrial production has been realized.

[0013] 4. The preparation method has simple process, low equipment requirement, no high-pressure special equipment, and is easy to realize large-scale production.

[0014] 5. The preparation method has high utilization efficiency of raw materials, no waste of metal raw materials caused by production waste in the process, low water consumption in the production process, and no need for sewage treatment, which has the advantages of environmental protection.

[0015] The oxygen evolution catalyst prepared in the present application is tested in 1.0M KOH aqueous solution, and the overpotential is only 260mV under the current density of 10mA / cm 2 , the overpotential is only 322mV under the current density of 100mA / cm 2 , and the current density has no obvious change after being tested for 45h under the current density of 10mA / cm 2 , and has good stability.

[0016] Drawings of the specification

[0017] Figure 1 X-ray diffraction pattern of the electrocatalytic oxygen evolution material Ni2Fe1S / NS@C prepared in Example 1;

[0018] Figure 2 Raman spectrum of the electrocatalytic oxygen evolution material Ni2Fe1S / NS@C prepared in Example 1;

[0019] Figure 3This is a scanning electron microscope image of the Ni2Fe1S / NS@C electrocatalytic oxygen evolution material prepared in Example 1;

[0020] Figure 4 Transmission electron microscopy (TEM) image of the Ni2Fe1S / NS@C electrocatalytic oxygen evolution material prepared in Example 1;

[0021] Figure 5 The energy dispersive X-ray spectrum of the electrocatalytic oxygen evolution material Ni2Fe1S / NS@C prepared in Example 1 is shown below.

[0022] Figure 6 To test the elemental mass fraction distribution of the electrocatalytic oxygen evolution material Ni2Fe1S / NS@C prepared in Example 1 using inductively coupled plasma atomic emission spectrometry;

[0023] Figure 7 The electrocatalytic oxygen evolution reaction performance of Ni2Fe1S / NS@C prepared in Example 1 and commercially available ruthenium dioxide is shown in the figure.

[0024] Figure 8 The graph shows the electrocatalytic stability test performance of the Ni2Fe1S / NS@C electrocatalytic oxygen evolution material prepared in Example 1.

[0025] Figure 9 Ni2Fe1S, an electrocatalytic oxygen evolution material prepared for comparative experiments + Scanning electron microscope image of / NS@C;

[0026] Figure 10 Ni2Fe1S, an electrocatalytic oxygen evolution material prepared for comparative experiments + Electrocatalytic oxygen evolution reaction performance of / NS@C and Ni2Fe1S / NS@C prepared in Example 1. Detailed Implementation

[0027] Specific Implementation Method 1: This implementation method is a simple and environmentally friendly method for preparing microcrystalline cellulose-based electrocatalytic oxygen evolution material, which is carried out according to the following steps:

[0028] 1. The metal precursor and coordination precursor are dissolved and dispersed in water, then microcrystalline cellulose is added and stirred evenly. Finally, the mixture is dried and ground evenly to obtain a solid powder.

[0029] The coordination precursor is one or a combination of several of the following: thiourea, sodium hypophosphite, urea, and ammonium chloride;

[0030] II. Under a protective gas atmosphere, the solid powder is calcined at high temperature and then cooled to room temperature, thus completing a simple and environmentally friendly method for preparing microcrystalline cellulose-based electrocatalytic oxygen evolution materials.

[0031] Compared with ordinary cellulose, microcrystalline cellulose has the characteristics of small size, large specific surface area and high crystallinity. This is conducive to the surface adsorption of a large number of transition metal ions, reduces the swelling of the non-crystalline region to make metal ions enter the interior of the cellulose, and avoids a large number of metal ions from nucleating in the interior of the carbon layer during high-temperature carbonization, thereby reducing the accessibility of active sites. Compared with nanocellulose, the synthesis method of microcrystalline cellulose is more mature and has realized industrial production. At present, there are still few studies on the use of microcrystalline cellulose for constructing electrocatalytic oxygen evolution materials. Therefore, the embodiment provides a simple and environmentally friendly preparation method of a microcrystalline cellulose-based electrocatalytic oxygen evolution material.

[0032] The beneficial effects of the embodiment are:

[0033] 1. In the preparation method of the embodiment, the microcrystalline cellulose has the advantages of small size, large specific surface area and high crystallinity, and the surface also contains a large number of hydroxyl groups, which is conducive to the surface adsorption of a large number of transition metal ions. The microcrystalline cellulose has high crystallinity and order, which is conducive to the formation of a graphitized structure during high-temperature calcination, thereby improving the conductivity of the catalyst. The formed biomass carbon material also has a certain spatial confinement effect, which is conducive to relieving the migration and agglomeration of metal particles and forming smaller particles. The production process of microcrystalline cellulose is mature, which is conducive to realizing large-scale production.

[0034] 2. The electrocatalyst prepared in the embodiment is specifically a heteroatom-doped carbon material surface loaded with transition metal compound nanoparticles, which has good OER activity and stability.

[0035] 3. The raw material cost of the method of the embodiment is low, and all have realized industrial production.

[0036] 4. The preparation method of the embodiment has a simple process, low equipment requirements, no high-pressure special equipment, and is easy to realize large-scale production.

[0037] 5. The preparation method of the embodiment has high utilization efficiency of raw materials, no waste of metal raw materials caused by production waste in the process, low water consumption in the production process, and no need for sewage treatment, which has the advantages of environmental protection.

[0038] The oxygen evolution catalyst prepared in the embodiment is tested in 1.0M KOH aqueous solution, and the overpotential is only 260mV at a current density of 10mA / cm 2 , the overpotential is only 322mV at a current density of 100mA / cm 2 , and the current density does not change significantly after being tested at a current density of 10mA / cm 2 for 45h, which has good stability.

[0039] Specific embodiment two: the difference between this embodiment and the specific embodiment one is that the metal precursor in step one is one or a combination of several of nickel nitrate, iron nitrate and cobalt nitrate. The others are the same as the specific embodiment one.

[0040] Specific embodiment three: the difference between this embodiment and one of the specific embodiment one or two is that the metal precursor in step one is nickel nitrate and iron nitrate, and the complex precursor is thiourea. The others are the same as the specific embodiment one or two.

[0041] Specific embodiment four: the difference between this embodiment and one of the specific embodiment one to three is that the mass ratio of the metal precursor to microcrystalline cellulose in step one is (0.1-3):1. The others are the same as the specific embodiment one to three.

[0042] Specific embodiment five: the difference between this embodiment and one of the specific embodiment one to four is that the mass ratio of the complex precursor to microcrystalline cellulose in step one is (0.1-2):1. The others are the same as the specific embodiment one to four.

[0043] Specific embodiment six: the difference between this embodiment and one of the specific embodiment one to five is that the protective gas in step two is one or a combination of several of nitrogen, helium, neon, argon, krypton and xenon. The others are the same as the specific embodiment one to five.

[0044] Specific embodiment seven: the difference between this embodiment and one of the specific embodiment one to six is that the high-temperature calcination in step two is specifically high-temperature calcination for 2-6 h under the conditions of a protective gas and a temperature of 700-1200℃. The others are the same as the specific embodiment one to six.

[0045] Specific embodiment eight: the difference between this embodiment and one of the specific embodiment one to seven is that the temperature is raised to 700-1200℃ at a temperature raising rate of 1-10℃ / min. The others are the same as the specific embodiment one to seven.

[0046] Specific embodiment nine: the difference between this embodiment and one of the specific embodiment one to eight is that the high-temperature calcination in step two is specifically high-temperature calcination for 2 h under the conditions of a nitrogen atmosphere and a temperature of 900℃. The others are the same as the specific embodiment one to eight.

[0047] Specific embodiment ten: the difference between this embodiment and one of the specific embodiment one to nine is that the temperature is raised to 900℃ at a temperature raising rate of 5℃ / min. The others are the same as the specific embodiment one to nine.

[0048] The following examples are used to verify the beneficial effects of the present application:

[0049] Example One:

[0050] A simple and environmentally friendly preparation method of microcrystalline cellulose-based electrocatalytic oxygen evolution material, which is carried out according to the following steps:

[0051] I. 0.291 g of nickel nitrate, 0.202 g of iron nitrate and 0.250 g of thiourea are added to water to dissolve and disperse, then 0.500 g of microcrystalline cellulose is added and stirred uniformly, finally dried for 12 h and ground uniformly to obtain a solid powder;

[0052] II. Under a nitrogen atmosphere, the solid powder is heated to 900℃ at a heating rate of 5℃ / min, then high-temperature calcination is carried out under a nitrogen atmosphere and at a temperature of 900℃ for 2 h, and finally cooled to room temperature to obtain the microcrystalline cellulose-based electrocatalytic oxygen evolution material, which is named as electrocatalytic oxygen evolution material Ni2Fe1S / NS@C.

[0053] Comparative experiment: The difference between this example and Example One is that 0.413 g of nickel nitrate and 0.287 g of iron nitrate are added, and the others are the same as Example One. The sample prepared in the comparative experiment is named as electrocatalytic oxygen evolution material Ni2Fe1S + / NS@C.

[0054] The electrocatalytic oxygen evolution material Ni2Fe1S / NS@C prepared in Example One is subjected to oxygen evolution reaction performance test. The test method is carried out in a 1.0 M potassium hydroxide aqueous solution at room temperature using a three-electrode system. Glassy carbon (GC, diameter 5 mm, 0.196 cm 2 ) is used as the working electrode, graphite rod as the counter electrode, and Ag / AgCl electrode as the reference electrode. The prepared electrocatalytic oxygen evolution material Ni2Fe1S / NS@C is dropped on the glassy carbon electrode head in the form of ink and slowly dried in air until a uniform catalyst covering layer is formed on the surface of the working electrode, and the catalyst loading is about 0.5 mg / cm 2 . The commercial ruthenium dioxide and the electrocatalytic oxygen evolution material Ni2Fe1S + / NS@C prepared in the comparative experiment are subjected to EER performance test using the same method. The stability test is carried out by coating the sample on a 1 cm x 2 cm hydrophilic carbon paper, and the catalyst loading is about 2.0 mg / cm 2 .

[0055] Figure 1 X-ray diffraction pattern of the electrocatalytic oxygen evolution material Ni2Fe1S / NS@C prepared in Example One; from the figure, it can be seen that the metal compounds on the surface of the electrocatalytic oxygen evolution material Ni2Fe1S / NS@C are mainly Fe5Ni4S8, and there is a small amount of Ni3S2.

[0056] Figure 2The Raman spectrum of the electrocatalytic oxygen evolution material Ni2Fe1S / NS@C prepared in Example 1; as can be seen from the figure, the intensity ratio of the D peak and the G peak of the electrocatalytic oxygen evolution material Ni2Fe1S / NS@C is 1, indicating that the material forms a certain graphite carbon structure.

[0057] Figure 3 The scanning electron microscope image of the electrocatalytic oxygen evolution material Ni2Fe1S / NS@C prepared in Example 1; as can be seen from the figure, in the electrocatalytic oxygen evolution material Ni2Fe1S / NS@C, the nickel-iron sulfide particles loaded on the surface of the microcrystalline cellulose-based carbon material have a particle size of 100 nm to 500 nm.

[0058] Figure 4 The transmission electron microscope image of the electrocatalytic oxygen evolution material Ni2Fe1S / NS@C prepared in Example 1; as can be seen from the figure, in the electrocatalytic oxygen evolution material Ni2Fe1S / NS@C, there are also smaller size nickel-iron sulfides loaded on the surface of the microcrystalline cellulose-based carbon material, with a particle size of 10 nm to 30 nm.

[0059] Figure 5 The energy dispersive X-ray spectrum of the electrocatalytic oxygen evolution material Ni2Fe1S / NS@C prepared in Example 1; as can be seen from the figure, in the electrocatalytic oxygen evolution material Ni2Fe1S / NS@C, the elements N and S exist on the surface of the carbon material, i.e. the carbon material is doped with N and S heteroatoms, and the particles are composed of Fe, Ni and S elements.

[0060] Figure 6 The element mass fraction distribution diagram of the electrocatalytic oxygen evolution material Ni2Fe1S / NS@C prepared in Example 1 tested by inductively coupled plasma emission spectrometer; as can be seen from the figure, in the electrocatalytic oxygen evolution material Ni2Fe1S / NS@C, the contained Ni and Fe elements respectively account for 14.30% and 6.79% of the total mass of the sample, having a relatively high loading amount.

[0061] Figure 7 The electrocatalytic oxygen evolution reaction performance diagram of the electrocatalytic oxygen evolution material Ni2Fe1S / NS@C prepared in Example 1 and the commercially purchased ruthenium dioxide; as can be seen from the figure, in 1.0M KOH aqueous solution, the electrocatalytic oxygen evolution material Ni2Fe1S / NS@C has an overpotential of only 260mV at a current density of 10mA / cm 2 , and an overpotential of only 322mV at a current density of 100mA / cm 2 , both of which are better than the commercially purchased ruthenium dioxide.

[0062] Figure 8 The electrocatalytic stability test performance diagram of the electrocatalytic oxygen evolution material Ni2Fe1S / NS@C prepared in Example 1; at 10mA / cm 2The current density of the electrocatalytic oxygen evolution material Ni2Fe1S / NS@C did not change significantly after 45h of testing at a current density of 10mA / cm2, and it had good stability.

[0063] Figure 9 The electrocatalytic oxygen evolution material Ni2Fe1S / NS@C prepared for the comparative experiment + The scanning electron microscope image of the electrocatalytic oxygen evolution material Ni2Fe1S / NS@C; as can be seen from the figure, in the electrocatalytic oxygen evolution material Ni2Fe1S / NS@C, the size of the nickel-iron sulfide particles loaded on the surface of the microcrystalline cellulose-based carbon material increased significantly compared to Ni2Fe1S / NS@C. This indicates that the amount of metal precursor added has an effect on the size of the metal compound. +

[0064] Figure 10 The electrocatalytic oxygen evolution material Ni2Fe1S / NS@C prepared for the comparative experiment + The electrocatalytic oxygen evolution reaction performance chart of the electrocatalytic oxygen evolution material Ni2Fe1S / NS@C prepared in Example 1 and the electrocatalytic oxygen evolution material Ni2Fe1S / NS@C prepared for the comparative experiment; as can be seen from the figure, in 1.0M KOH aqueous solution, the electrocatalytic oxygen evolution material Ni2Fe1S / NS@C has an overpotential of 295mV at a current density of 10mA / cm2, and an overpotential of 394mV at a current density of 100mA / cm2, both of which are higher than those of Ni2Fe1S / NS@C. This indicates that the amount of metal precursor added has an effect on the OER activity. + 2 2 The electrocatalytic oxygen evolution reaction performance chart of the electrocatalytic oxygen evolution material Ni2Fe1S / NS@C prepared in Example 1 and the electrocatalytic oxygen evolution material Ni2Fe1S / NS@C prepared for the comparative experiment; as can be seen from the figure, in 1.0M KOH aqueous solution, the electrocatalytic oxygen evolution material Ni2Fe1S / NS@C has an overpotential of 295mV at a current density of 10mA / cm2, and an overpotential of 394mV at a current density of 100mA / cm2, both of which are higher than those of Ni2Fe1S / NS@C. This indicates that the amount of metal precursor added has an effect on the OER activity.​​​

Claims

1. A simple and environmentally friendly method for preparing a microcrystalline cellulose-based electrocatalytic oxygen evolution material Ni2Fe1S / NS@C, characterized in that... It is done in the following steps:

1. The metal precursor and coordination precursor are dissolved and dispersed in water, then microcrystalline cellulose is added and stirred evenly. Finally, the mixture is dried and ground evenly to obtain a solid powder. The metal precursors are nickel nitrate and iron nitrate, and the coordination precursor is thiourea; The mass ratio of the metal precursor to microcrystalline cellulose is (0.1~3):1; The mass ratio of the coordination precursor to microcrystalline cellulose is (0.1~2):1; 2. Under a protective gas, the temperature is raised to 900℃ at a heating rate of 5℃ / min. Under the conditions of a protective gas and a temperature of 900℃, the solid powder is calcined at high temperature for 2 hours and finally cooled to room temperature to obtain microcrystalline cellulose-based electrocatalytic oxygen evolution material. This completes the simple and environmentally friendly preparation method of microcrystalline cellulose-based electrocatalytic oxygen evolution material. The microcrystalline cellulose-based electrocatalytic oxygen evolution material contains 100nm~500nm nickel-iron sulfide particles and 10nm~30nm nickel-iron sulfide particles loaded on the surface of the microcrystalline cellulose-based carbon material, and the microcrystalline cellulose-based carbon material is doped with N and S heteroatoms.

2. The method for preparing a simple and environmentally friendly microcrystalline cellulose-based electrocatalytic oxygen evolution material Ni2Fe1S / NS@C according to claim 1, characterized in that... The protective gas mentioned in step two is one or a combination of nitrogen, helium, neon, argon, krypton and xenon.

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