A multi-stage radial microspherical alkali phosphate-carbon nitride composite material, a preparation method and application thereof

Abstract

A kind of multistage radial microspherical basic phosphate-nitrogen carbon composite material and its preparation method and application.The carbon nitride is dispersed in deionized water to obtain suspension A;Phosphate is dissolved in suspension A to obtain mixed solution B;Take transition metal acetate powder is dissolved in deionized water to obtain transparent solution C;B mixed solution is placed in an open container, in the state of static, solution C is sprayed into mixed solution B, and the precursor of flocculent insoluble is generated;The precursor is transferred into the container, and the floating flocculent is converted into precipitate under the condition of sealing;After falling to room temperature, the obtained precipitate is separated and washed and dried, to obtain multistage radial microspherical basic phosphate-nitrogen carbon composite material.The morphology of the prepared composite material is microspherical, and there is an opening in the middle of the microsphere, and the microsphere is assembled by radial divergence of nanorod with gap.Application in electrocatalytic material, secondary ion battery electrode material, photocatalytic material and photoanode material.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of nanomaterials and electrochemistry, and in particular to a multi-stage radial microspherical alkali phosphate-carbon nitride composite material, a preparation method therefor and an application thereof. BACKGROUND

[0002] By utilizing solar energy to electrolyze water and then producing hydrogen as fuel, a perfect path for realizing sustainable development is provided. However, to realize this path, an electrocatalyst must be used to reduce the reaction energy barrier of hydrogen production by electrolysis of water, so as to save electric energy and reduce production cost.

[0003] At present, Pt is the most efficient hydrogen evolution electrocatalyst, but its abundance is low and its price is high, which limits its large-scale popularization and application. The urgent task is to develop efficient non-noble metal electrocatalysts, and among them, transition metal alkali phosphates have a typical layered structure, can provide a large specific surface area and thus generate sufficient catalytic active sites. The multiple oxidation states of transition metal ions make them have rich redox behavior, and the protons of the phosphate group can diffuse in the interlayer region, which can increase the mass transfer speed and promote ion migration. These characteristics make them have unique advantages in electrocatalysis. However, alkali phosphates have high impedance and poor corrosion resistance, and need to be appropriately modified to meet the practical needs.

[0004] Currently there are few methods for the preparation of transition metal basic phosphate composite. Copper site attraction method [Zhou W, Chen Xiaofang. Basic copper phosphate coated diatomite composite and plastic composition and plastic products containing the same and their preparation methods [P]. Patent number: CN201510627214.6]. In addition, there are few reports. For example, the preparation method of transition metal phosphate is to use the precipitation method to prepare cobalt phosphate-carbon nitride nanosheet [Shi W, Li M, Huang X, et al. Facile synthesis of 2D / 2D Co3(PO4)2 / g-C3N4 heterojunction for highly photocatalytic overall water splitting under visible light [J]. Chemical Engineering Journal, 2020, 382: 122960.]. In situ photodeposition preparation of cobalt phosphate-carbon composite [Ge L, Han C, Xiao X, et al. In situ synthesis of cobalt-phosphate (Co-Pi) modified g-C3N4 photocatalysts with enhanced photocatalytic activities [J]. Applied Catalysis B: Environmental, 2013, 142: 414-422.]. Solvothermal preparation of nickel phosphate / nickel phosphide hollow microspheres [Chang J, Lv Q, Li G, et al. Core-shell structured Ni 12 P5 / Ni3(PO4)2hollow spheres as difunctional and efficient electrocatalysts for overall water electrolysis [J]. Applied Catalysis B: Environmental, 2017, 204: 486-496.]. High-energy ball milling preparation of copper phosphate / carbon composite [Zhao W, Zhong G, McDonald M J, et al. Cu3(PO4)2 / C composite as a high-capacity cathode material for rechargeable Na-ion batteries [J]. Nano energy, 2016, 27: 420-429.]

[0005] It can be found that there are few reports on the preparation of basic phosphate nanocomposites, and in the above reported methods, the copper site attraction method makes the prepared material unable to be used for water electrolysis, the process is complicated, and the preparation process takes a long time. For the technical route of preparing other similar substances, the high-energy ball milling method has high energy consumption and cannot control the morphology of the product. The solvothermal method involves high temperature and high pressure reaction conditions, and the use of organic solvents increases the production cost. The material prepared by the in-situ photodeposition method is amorphous phosphate with very little content. SUMMARY

[0006] The purpose of the present application is to provide a multi-stage radial microspherical basic phosphate-carbon nitride composite material and its preparation method and application in view of the above-mentioned technical problems.

[0007] To achieve the above-mentioned purpose, the preparation method of the present application is as follows:

[0008] 1) Disperse carbon nitride uniformly in deionized water to obtain a suspension A with a concentration of 0.5-5 mg / mL;

[0009] 2) Dissolve phosphate in the suspension A to obtain a mixed solution B with a phosphate concentration of 5-100 mmol / L;

[0010] 3) Dissolve transition metal acetate powder in deionized water to form a transparent solution C with a concentration of 1-50 mmol / L;

[0011] 4) Take the mixed solution B and the solution C with a volume ratio of 10:1, place the mixed solution B in an open container, and spray the solution C into the mixed solution B under static state to generate a flocculent insoluble precursor;

[0012] 5) Transfer the precursor obtained in 4) into a container, and incubate under a sealed condition at 30-150°C to convert the floating flocculent into a precipitate;

[0013] 6) After the incubation is completed, the obtained precipitate is separated and washed and dried to obtain a multi-stage radial microspherical basic phosphate-carbon nitride composite material.

[0014] The carbon nitride of step 1) is in a nanosheet structure.

[0015] The phosphate of step 2) is one or a mixture of more than one of diammonium hydrogen phosphate, disodium hydrogen phosphate, dipotassium hydrogen phosphate in any proportion.

[0016] The phosphate concentration of step 2) is 5-10 mmol / L.

[0017] The transition metal acetate of step 3) is cobalt acetate, iron acetate, nickel acetate or copper acetate.

[0018] The concentration of the transparent solution C in the step 3) is 1-5 mmol / L.

[0019] The spraying speed of the liquid in the step 4) is greater than or equal to 1 mL / s.

[0020] The ripening in the step 5) adopts direct heating, water bath heating or oil bath heating.

[0021] The multi-level radial microspherical basic phosphate-carbon nitride composite material prepared by the above preparation method has a microspherical morphology, and an opening exists in the middle of the microsphere, the microsphere is assembled by nanorods with gaps between the nanorods in a radial divergent manner, and the nanorods have obvious gaps, so that the specific surface area of the material can be greatly improved, and more reaction active sites are provided.

[0022] The multi-level radial microspherical basic phosphate-carbon nitride composite material prepared by the above preparation method is applied as an electrocatalytic material, a secondary ion battery electrode material, a photocatalytic material and a photoanode material.

[0023] Compared with the prior art, the application has the following beneficial technical effects:

[0024] The method for preparing the multi-level radial microspherical basic phosphate-carbon nitride composite material has the following characteristics: (1) the basic phosphate is nucleated and grown on the surface of carbon nitride by utilizing the characteristics of carbon nitride, such as stable chemical properties and rich unsaturated bonds on the surface, the morphology of the basic phosphate is jointly controlled by the space limitation of carbon nitride and the adsorption characteristics of acetate, and then a heterojunction structure in which the basic phosphate and carbon nitride are uniformly combined is obtained; (2) the electronic structure of the material is controlled by establishing the heterojunction structure, and then the electrocatalytic reaction path is optimized, and the electrocatalytic performance of the material is improved; (3) the preparation process of the application requires few control factors, and the requirements for equipment and instruments are very simple, and the obtained material has a rich pore structure and a large specific surface area; (4) the preparation process is simple, easy to control and operate, safe and stable, environmentally friendly, and easy to realize industrialized production. BRIEF DESCRIPTION OF DRAWINGS

[0025] Figure 1 is an XRD graph of the multi-level radial microspherical copper basic phosphate-carbon nitride nanocomposite material prepared in Example 4 of the application;

[0026] Figure 2 is an SEM graph of the multi-level radial microspherical copper basic phosphate-carbon nitride nanocomposite material prepared in Example 4 of the application;

[0027] Figure 3 is a linear sweep voltammetry curve graph of the performance of the multi-level radial microspherical copper basic phosphate-carbon nitride nanocomposite material prepared in Example 4 of the application for electrocatalytic hydrogen evolution.

[0028] Figure 4 Figure 4 is a linear sweep voltammetry plot of the performance of the multi-level radial microspherical copper hydroxyl phosphate-carbon nitride nanocomposite material prepared in Example 4 for electrocatalytic oxygen evolution. DETAILED DESCRIPTION

[0029] The application will be further described in detail below with reference to the accompanying drawings and examples:

[0030] Example 1

[0031] 1) Carbon nitride nanosheets were added to deionized water, and after ultrasonic oscillation for 1 h, magnetic stirring was continued for 1 h to obtain a suspension A with a concentration of 2.5 mg / mL;

[0032] 2) Phosphate diammonium hydrogen phosphate was added to the suspension A, and magnetic stirring was performed for 0.5 h to obtain a mixed solution B with a phosphate concentration of 10 mmol / L;

[0033] 3) Transition metal acetate cobalt acetate powder was taken and added to deionized water, and magnetic stirring was performed for 2 h to form a transparent solution C with a concentration of 5 mmol / L;

[0034] 4) Mixed solution B and solution C were taken in a volume ratio of 10:1, mixed solution B was placed in an open container, and solution C was sprayed into mixed solution B at a spraying speed of 10 mL / s under a static state to generate a precursor of flocculent insoluble substance;

[0035] 5) The precursor obtained in 4) was transferred into a container, and the floating flocculent substance was converted into a precipitate under a sealed condition at 60°C;

[0036] 6) After the completion of the curing, the obtained precipitate was separated and washed and dried to obtain a multi-level radial microspherical phosphate-carbon nitride composite material.

[0037] Example 2

[0038] 1) Carbon nitride nanosheets were added to deionized water, and after ultrasonic oscillation for 1 h, magnetic stirring was continued for 1 h to obtain a suspension A with a concentration of 2 mg / mL;

[0039] 2) Phosphate disodium hydrogen phosphate was added to the suspension A, and magnetic stirring was performed for 0.5 h to obtain a mixed solution B with a phosphate concentration of 5 mmol / L;

[0040] 3) Transition metal acetate iron acetate powder was taken and added to deionized water, and magnetic stirring was performed for 1 h to form a transparent solution C with a concentration of 3 mmol / L;

[0041] 4) Take mixed solution B and solution C with a volume ratio of 10:1, place mixed solution B in an open container, and spray solution C into mixed solution B at a spraying speed of 8 mL / s under static state to generate the precursor of flocculent insoluble substance;

[0042] 5) Transfer the precursor obtained in 4) into a container, and heat to 70°C in a water bath under sealed condition to mature, so that the floating flocculent substance is converted into a precipitate;

[0043] 6) After the maturation is completed, the obtained precipitate is separated, washed and dried after being cooled to room temperature, to obtain a multi-level radial microspherical alkali phosphate-carbon nitride composite material.

[0044] Example 3

[0045] 1) Add carbon nitride nanosheets into deionized water, and continue to magnetically stir for 1 h after ultrasonic oscillation for 1 h, to obtain a suspension A with a concentration of 1.5 mg / mL;

[0046] 2) Add a mixture of phosphate dipotassium hydrogen phosphate and disodium hydrogen phosphate into suspension A, and magnetically stir for 0.5 h to obtain a mixed solution B with a phosphate concentration of 8 mmol / L;

[0047] 3) Take transition metal acetate nickel acetate powder into deionized water, and magnetically stir for 2 h to form a transparent solution C with a concentration of 1 mmol / L;

[0048] 4) Take mixed solution B and solution C with a volume ratio of 10:1, place mixed solution B in an open container, and spray solution C into mixed solution B at a spraying speed of 5 mL / s under static state to generate the precursor of flocculent insoluble substance;

[0049] 5) Transfer the precursor obtained in 4) into a container, and heat to 80°C in a water bath under sealed condition to mature, so that the floating flocculent substance is converted into a precipitate;

[0050] 6) After the maturation is completed, the obtained precipitate is separated, washed and dried after being cooled to room temperature, to obtain a multi-level radial microspherical alkali phosphate-carbon nitride composite material.

[0051] Example 4

[0052] 1) Add carbon nitride nanosheets into deionized water, and continue to magnetically stir for 1 h after ultrasonic oscillation for 1 h, to obtain a suspension A with a concentration of 1 mg / mL;

[0053] 2) Add phosphate diammonium hydrogen phosphate into suspension A, and magnetically stir for 0.5 h to obtain a mixed solution B with a phosphate concentration of 8 mmol / L;

[0054] 3) Take transition metal acetate copper acetate powder into deionized water, and magnetically stir for 2 h to form a transparent solution C with a concentration of 1 mmol / L;

[0055] 4) Take mixed solution B and solution C at a volume ratio of 10:1, place mixed solution B in an open container, and spray solution C into mixed solution B at a spray speed of 1 mL / s under static conditions to generate a precursor of flocculent insoluble substance;

[0056] 5) Transfer the precursor obtained in 4) into a container, and heat to 80°C in a water bath under sealed conditions to convert the floating flocculent substance into a precipitate;

[0057] 6) After the completion of the aging, after being cooled to room temperature, separate and wash the obtained precipitate and dry to obtain a multi-level radial microspherical alkali phosphate-carbon nitride composite material.

[0058] As can be seen from Figure 1 , the diffraction peaks of the prepared material well match standard card 36-0403, and the corresponding phase is Cu2(PO4)(OH), and the diffraction peak is sharp in shape and has good crystallinity. More importantly, a diffraction peak attributed to the graphite phase of carbon nitride appears at 27.5°, which shows that the alkali copper phosphate-carbon nitride composite material can be obtained by using the technical route in the application.

[0059] As can be seen from Figure 2 , the prepared alkali copper phosphate-carbon nitride composite material presents a microspherical morphology with intermediate separation. It can be found from the broken microspheres that the microspherical morphology is assembled by a section of aggregated nanocolumns in a radial divergent form, and there is a rich gap structure between the nanocolumns. This shows that the material has a high specific surface area. This can greatly increase the contact area of the material with the electrolyte and provide more active sites for reaction.

[0060] As can be seen from Figure 3 and Figure 4 , the prepared alkali copper phosphate-carbon nitride composite material is used for electrocatalytic decomposition of water. In an alkaline condition, when the current density of the hydrogen evolution and oxygen evolution reactions reaches 10 mA / cm 2 , the corresponding overpotential is 189 mV and 404 mV, respectively, which shows good electrocatalytic hydrogen evolution and oxygen evolution properties. This shows that the prepared alkali copper phosphate-carbon nitride composite material can be used as a bifunctional catalyst for water electrolysis, and has great application potential.

[0061] Example 5

[0062] 1) Add carbon nitride nanosheets to deionized water, ultrasonically shake for 1 h, and then continue to magnetically stir for 1 h to obtain a suspension A with a concentration of 0.5 mg / mL;

[0063] 2) Add phosphate dipotassium hydrogen phosphate to the suspension A, and magnetically stir for 1 h to obtain a mixed solution B with a phosphate concentration of 50 mmol / L;

[0064] 3) Take the transition metal acetate cobalt acetate powder into deionized water, magnetic stirring for 0.5h to form a concentration of 20mmol / L transparent solution C;

[0065] 4) Take mixed solution B and solution C with a volume ratio of 10:1, place mixed solution B in an open container, under the condition of static state, spray solution C into mixed solution B at a spray speed of 3mL / s, to generate the precursor of flocculent insoluble substance;

[0066] 5) Transfer the precursor obtained in 4) into a container, heat to 30℃ under sealed condition in an oil bath to mature, so that the floating flocculent material is converted into a precipitate;

[0067] 6) After the maturation is completed, after being reduced to room temperature, separate and wash the obtained precipitate and dry to obtain a multi-level radial microspherical alkali phosphate-carbon nitride composite material.

[0068] Example 6

[0069] 1) Put carbon nitride nanosheet into deionized water, ultrasonic oscillation for 1h, then continue magnetic stirring for 1h to obtain a suspension A with a concentration of 5mg / mL;

[0070] 2) Put phosphate diammonium hydrogen phosphate into suspension A, magnetic stirring for 2h to obtain mixed solution B with a phosphate concentration of 100mmol / L;

[0071] 3) Take the transition metal acetate copper acetate powder into deionized water, magnetic stirring for 2h to form a concentration of 50mmol / L transparent solution C;

[0072] 4) Take mixed solution B and solution C with a volume ratio of 10:1, place mixed solution B in an open container, under the condition of static state, spray solution C into mixed solution B at a spray speed of 7mL / s, to generate the precursor of flocculent insoluble substance;

[0073] 5) Transfer the precursor obtained in 4) into a container, heat to 150℃ under sealed condition to mature, so that the floating flocculent material is converted into a precipitate;

[0074] 6) After the maturation is completed, after being reduced to room temperature, separate and wash the obtained precipitate and dry to obtain a multi-level radial microspherical alkali phosphate-carbon nitride composite material.

Claims

1. A method for preparing a multi-level radial microspherical basic phosphate-carbon nitride composite material, characterized in that, The preparation method comprises the following steps: 1) uniformly dispersing carbon nitride in deionized water to obtain a suspension A with a concentration of 0.5-5 mg / mL; 2) dissolving a phosphate in the suspension A to obtain a mixed solution B with a phosphate concentration of 5-100 mmol / L; 3) dissolving a transition metal acetate powder in deionized water to form a transparent solution C with a concentration of 1-50 mmol / L; the transition metal acetate is cobalt acetate, iron acetate, nickel acetate or copper acetate; 4) taking the mixed solution B and the solution C at a volume ratio of 10:1, placing the mixed solution B in an open container, and spraying the solution C into the mixed solution B at a spraying speed of ≥1 mL / s under a static state to generate a precursor of flocculent insoluble substances; 5) transferring the precursor obtained in 4) into a container, and curing the precursor under a sealed condition at 30-150°C to convert the floating flocculent substances into a precipitate; 6) after the curing is completed, the obtained precipitate is separated, washed and dried to obtain a multi-level radial microspherical alkali phosphate-carbon nitride composite material; the multi-level radial microspherical alkali phosphate-carbon nitride composite material has a microspherical morphology, and an opening exists in the middle of the microsphere; the microsphere is assembled by radially diverging nanorods with gaps between the nanorods.

2. The preparation method of the multistage radial microspheroidal base phosphate-carbon nitride composite material according to claim 1, characterized in that: the carbon nitride in step 1) has a nanosheet structure.

3. The preparation method of the multi-stage radial microspheroidal base phosphate-carbon nitride composite material according to claim 1, characterized in that: the phosphate in step 2) is at least one of diammonium hydrogen phosphate, disodium hydrogen phosphate and dipotassium hydrogen phosphate.

4. The preparation method of multi-stage radial microspheroidal base phosphate-carbon nitride composite material according to claim 1, characterized in that: the phosphate concentration in step 2) is 5-10 mmol / L.

5. The preparation method of multi-stage radial microspheroidal base phosphate-carbon nitride composite material according to claim 1, characterized in that: the concentration of the transparent solution C in step 3) is 1-5 mmol / L.

6. The method for preparing the multi-level radial microspherical basic phosphate-carbon nitride composite material according to claim 1, characterized in that: the curing in step 5) adopts direct heating, water bath heating or oil bath heating.

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