Preparation method and application of metal phthalocyanine-graphite phase carbon nitride / graphene ternary composite material

Abstract

The present application relates to a kind of preparation method and application of metal phthalocyanine-graphite phase carbon nitride / graphene ternary composite material, it solves the problem of poor dispersibility, easy aggregation and poor conductivity of metal phthalocyanine material as electrocatalyst.Existing Preparation method steps include: metal phthalocyanine, graphite phase carbon nitride are added to sulfuric acid, after heating stirring, solution A is prepared by cooling;Solution B is prepared by stirring after adding sodium nitrite to solution A under ice bath;Graphene oxide is ultrasonically dispersed in distilled water to prepare solution C;Solution B is added dropwise to solution C and stirred, then ascorbic acid is added and stirred, the product is centrifuged, washed and dried to prepare metal phthalocyanine-graphite phase carbon nitride / graphene ternary composite material.The ternary composite material prepared by the method is a two-dimensional sheet structure, has high dispersibility, large specific surface area, good conductivity and structural stability;The product of the present application can be used for electrocatalytic reduction of carbon dioxide.

Description

Technical Field

[0001] This invention relates to the field of electrocatalyst technology; specifically, it relates to a ternary composite material of metal phthalocyanine-graphite phase carbon nitride / graphene, its preparation method, and its application. Background Technology

[0002] The extensive use of fossil fuels has led to a significant increase in atmospheric carbon dioxide (CO2) concentration, resulting in a series of environmental problems such as global warming and ocean acidification. Utilizing catalysts to electroreducively reduce CO2 to produce high-value-added chemicals or fuels is an effective way to simultaneously achieve carbon cycling and the storage and conversion of electrical energy into chemical energy, attracting widespread attention from scientists and industry. However, due to the molecular inertness of CO2 and the complex proton and electron transfer processes involved in the reaction, efficiently, selectively, and cost-effectively electroreducing CO2 into specific products remains challenging. Therefore, the scientific and rational design and preparation of CO2 electroreduction catalysts is currently a key focus and challenge in the research for the industrial application of CO2 electroreduction technology.

[0003] Recent studies have shown that metal phthalocyanines exhibit outstanding reactivity and selectivity for carbon monoxide (CO) in the electrocatalytic reduction of carbon dioxide. However, due to the strong p-covalent interactions between their planar conjugated structures, the molecules are prone to stacking and aggregation, thus masking the active sites. Furthermore, the poor conductivity of metal phthalocyanines themselves hinders electron transfer to the active centers during electrocatalysis, limiting their further development. Currently, a common approach to improvement is to load metal phthalocyanines onto high-surface-area, highly conductive support materials (such as carbon nanotubes, graphene, and molybdenum sulfide). This is typically achieved through mechanical mixing and physical adsorption of the metal phthalocyanines and the support material in organic solvents (such as N,N-dimethylformamide and tetrahydrofuran). This strategy mitigates the problems of excessive aggregation and poor conductivity of metal phthalocyanines to some extent. However, because the interaction between metal phthalocyanine molecules and the support material is only a relatively weak non-covalent bond, metal phthalocyanines are still prone to re-aggregation, detachment, and deactivation during electrocatalysis, severely impacting catalytic activity and stability. In the electrocatalytic reduction of CO2, besides the number of exposed active sites and the intrinsic activity of these sites, increasing the local CO2 concentration on the catalyst surface is equally crucial for improving the catalytic conversion efficiency. Integrating components with CO2-capturing and enriching effects into the catalyst holds promise for increasing the local CO2 concentration on the catalyst surface, thereby enhancing the selectivity and conversion efficiency of CO2 reduction. However, this surface enrichment strategy for CO2 has not yet been well explored. Graphitic carbon nitride possesses a layered structure similar to graphene, which offers a potentially high specific surface area. Furthermore, the high proportion of nitrogen in carbon nitride (e.g., pyridine nitrogen, graphitic nitrogen, and amino nitrogen) can effectively increase the basic sites on the catalyst surface, thereby increasing the enrichment concentration of CO2 on the catalyst surface. However, graphitic carbon nitride is typically a bulk material obtained by high-temperature sintering of small-molecule precursors containing nitrogen and carbon elements (e.g., urea, melamine, etc.), making it difficult to disperse and resulting in a low specific surface area. Although methods such as chemical oxidation, mechanical spheroidization, and ultrasonic exfoliation have been developed to obtain single-layer or few-layer graphitic carbon nitride materials, these methods generally suffer from low yields, poor performance, and a tendency to re-aggregate, while also being difficult to integrate with other materials. Therefore, developing effective strategies, seeking simple and efficient modification methods and preparation techniques, and synthesizing highly efficient metal phthalocyanine-based CO2 electroreduction catalysts for practical application are currently important issues that urgently need to be addressed. Summary of the Invention

[0004] In view of the shortcomings of the prior art, the present invention aims to provide a method for preparing and applying a ternary composite material of metal phthalocyanine-graphite phase carbon nitride / graphene.

[0005] Metal phthalocyanines are excellent catalytic active centers, but many active sites are masked due to their difficulty in dispersion, easy stacking, and poor conductivity. This invention solves the problem of easy aggregation and difficulty in dispersion of metal phthalocyanines by bonding the edge structure of molecularly dispersed graphitic carbon nitride with metal phthalocyanines to form a metal phthalocyanine-graphitic carbon nitride conjugate. At the same time, the large number of alkaline sites on the surface of graphitic carbon nitride have an electrostatic attraction effect on carbon dioxide, which helps to increase the local carbon dioxide concentration on the catalyst surface, thereby improving the ability of the metal phthalocyanine active sites to electrocatalyze the reduction of CO2.

[0006] To further improve the conductivity and structural stability of metal phthalocyanine materials, this invention organically assembles molecularly dispersed metal phthalocyanine-graphite phase carbon nitride conjugates with graphene, which has excellent conductivity and a large specific surface area, through electrostatic and PP interactions. This process inhibits the self-stacking of the metal phthalocyanine-graphite phase carbon nitride conjugates, enhancing structural stability, while also effectively improving the conductivity and specific surface area of ​​the catalytic material.

[0007] This invention utilizes metal phthalocyanine, graphitic carbon nitride, concentrated sulfuric acid, sodium nitrite, graphene oxide, and distilled water to prepare a metal phthalocyanine-graphitic carbon nitride / graphene ternary composite material for the electrocatalytic reduction of carbon dioxide. This is achieved through the following steps:

[0008] Step 1: Add 25–125 mg of metal phthalocyanine powder and 0.5–1 g of graphitic carbon nitride powder to 5–10 mL of sulfuric acid solution with a concentration of 90–98%. Seal and stir for 2 h at 90–110 °C, then cool to room temperature to obtain solution A.

[0009] Step 2: Under ice bath conditions, add 10-25 mg of sodium nitrite powder to solution A obtained in step 1 and stir for 1 h to obtain solution B;

[0010] Step 3: Weigh 150–450 mg of graphene oxide powder and add it to 150 mL of distilled water. Disperse the powder by sonication for 2 h to obtain solution C.

[0011] Step 4: At 25 °C, 1–5 mL of solution B obtained in Step 2 is added dropwise to 150 mL of solution C obtained in Step 3 within 2 minutes. The mixture is stirred for 1 h, then 100 mg of ascorbic acid is added, and stirring is continued for 1 h. The product is separated by centrifugation and washed 3–5 times with distilled water and ethanol, respectively. The product is then dried at 80 °C to obtain the metal phthalocyanine-graphite phase carbon nitride / graphene ternary composite material.

[0012] The metal phthalocyanine in the metal is cobalt, nickel or iron; the graphitic carbon nitride can be prepared from urea or melamine; and the graphene oxide is prepared by the Hummers method.

[0013] A ternary composite material of metal phthalocyanine-graphite phase carbon nitride / graphene was prepared by the above method, which can be used as an electrocatalyst for the electrocatalytic reduction of carbon dioxide.

[0014] Compared with the prior art, the present invention has the following outstanding advantages:

[0015] This invention solves the problem of difficult dispersion of metal phthalocyanine and graphitic carbon nitride. It dissolves metal phthalocyanine and graphitic carbon nitride through a solvothermal reaction, allowing them to exist in a free state in concentrated sulfuric acid, forming a green and transparent solution. A diazotization reaction bonds the metal phthalocyanine and graphitic carbon nitride: the graphitic carbon nitride, with its edge structure resembling that of a primary aromatic amine, generates a diazo group under the action of sodium nitrite, which reacts with the aromatic ring of the metal phthalocyanine. This results in a planar conjugate between the free metal phthalocyanine and the graphitic carbon nitride in the solution, significantly improving the stability of the metal phthalocyanine while dispersing them at the molecular level.

[0016] This invention solves the problem of stacking during the precipitation of metal phthalocyanine-graphite phase carbon nitride conjugates. When dispersed in water, the metal phthalocyanine-graphite phase carbon nitride conjugates suffer from reduced specific surface area and masked active sites due to layer stacking. Through electrostatic interactions, graphene oxide and the metal phthalocyanine-graphite phase carbon nitride conjugates attract and assemble to form supramolecular structures. Electrostatic interactions anchor the conjugates to the graphene oxide surface, preventing stacking. The anchoring scale can be controlled by adjusting the graphene oxide concentration, stirring speed, and dropping speed. Furthermore, the binding strength between the conjugates and graphene is further enhanced by reducing the functional groups on the graphene oxide surface with ascorbic acid, thus improving chemical stability.

[0017] This invention relates to a ternary composite material of metal phthalocyanine and graphitic carbon nitride / graphene. In this material, metal phthalocyanine serves as the active site, graphitic carbon nitride increases the local concentration of reactants during the reaction, and metal phthalocyanine and graphitic carbon nitride are covalently bonded through diazotization to improve the stability of metal phthalocyanine. Graphene acts as a conductor and support. Through ingenious design and synthesis, this high-performance electrocatalyst has significant application value in the field of electrocatalytic carbon dioxide reduction.

[0018] The method for preparing the above-mentioned metal phthalocyanine-graphite phase carbon nitride / graphene ternary composite material provided by this invention is simple, environmentally friendly, and has a high yield. The obtained product has the characteristics of uniform morphology, good dispersibility, large specific surface area, high conductivity, and stable structure. This preparation method has the advantages of low cost, green environmental protection, and ease of large-scale production. Attached Figure Description

[0019] Figure 1 A schematic diagram of the metal phthalocyanine-graphite phase carbon nitride / graphene ternary composite material prepared in Embodiment 1;

[0020] Figure 2 A scanning electron microscope image of the cobalt phthalocyanine-graphite phase carbon nitride / graphene ternary composite material prepared in Embodiment 1;

[0021] Figure 3 Transmission electron microscope image and energy dispersive spectra of nitrogen and cobalt for the cobalt phthalocyanine-graphite phase carbon nitride / graphene ternary composite material prepared in Embodiment 1.

[0022] Figure 4 The images show the cobalt phthalocyanine-graphite phase carbon nitride / graphene ternary composite material prepared in Embodiment 1, and cobalt phthalocyanine dispersed in water (concentration of 1.0 mg / mL), and allowed to stand for 2 hours. In A, the solute is cobalt phthalocyanine; in B, the solute is the cobalt phthalocyanine-graphite phase carbon nitride / graphene ternary composite material.

[0023] Figure 5 The full X-ray photoelectron spectroscopy spectrum of the cobalt phthalocyanine-graphite phase carbon nitride / graphene ternary composite material prepared in Embodiment 1;

[0024] Figure 6 X-ray diffraction pattern of the cobalt phthalocyanine-graphite phase carbon nitride / graphene ternary composite material prepared in Embodiment 1;

[0025] Figure 7 The infrared spectrum of the cobalt phthalocyanine-graphite phase carbon nitride / graphene ternary composite material prepared in Embodiment 1;

[0026] Figure 8 The image shows the UV-Vis absorption spectrum of the cobalt phthalocyanine-graphite phase carbon nitride / graphene ternary composite material prepared in Implementation Method 1 in DMF solvent.

[0027] Figure 9 The nitrogen isothermal adsorption-desorption curve of the cobalt phthalocyanine-graphite phase carbon nitride / graphene ternary composite material prepared in Embodiment 1 is shown.

[0028] Figure 10 Thermogravimetric analysis curve of the cobalt phthalocyanine-graphite phase carbon nitride / graphene ternary composite material prepared in Embodiment 1;

[0029] Figure 11 The current-voltage characteristic curve of the cobalt phthalocyanine-graphite phase carbon nitride / graphene ternary composite material prepared in Embodiment 1 is shown.

[0030] Figure 12 The diagram shows the Faraday efficiency versus current density of the cobalt phthalocyanine-graphite phase carbon nitride / graphene ternary composite electrode prepared in Embodiment 6 for the electrocatalytic reduction of carbon dioxide to carbon monoxide. Detailed Implementation

[0031] Implementation method 1:

[0032] This embodiment describes the preparation of a cobalt phthalocyanine-graphite phase carbon nitride / graphene ternary composite material:

[0033] Step 1: Add 125 mg of cobalt phthalocyanine powder and 1 g of graphitic carbon nitride powder to 10 mL of 98% sulfuric acid solution, seal and stir for 2 h at 110 ℃, cool to room temperature to obtain solution A;

[0034] Step 2: Under ice bath conditions, add 25 mg of sodium nitrite powder to solution A obtained in step 1 and stir for 1 hour to obtain solution B;

[0035] Step 3: Weigh 450 mg of graphene oxide powder and add it to 30 mL of distilled water. Disperse the powder by ultrasonication for 2 h to obtain solution C.

[0036] Step 4: At 25 °C, 5 mL of solution B obtained in step 2 is added dropwise to 150 mL of solution C obtained in step 3 within 2 minutes, stirred for 1 h, then 100 mg of ascorbic acid is added, and stirring is continued for 1 h. The product is separated by centrifugation, washed 3 to 5 times with distilled water and ethanol respectively, and dried at 80 °C to obtain the cobalt phthalocyanine-graphite phase carbon nitride / graphene ternary composite material.

[0037] The preparation method of graphitic carbon nitride is as follows:

[0038] Add 10 g of urea or melamine to a ceramic boat, wrap it with aluminum foil, place it in a muffle furnace, heat it to 500 ℃ at 2.3 ℃ / min, hold it for 2 hours, then heat it to 520 ℃ at 2.3 ℃ / min, hold it for 2 hours, and anneal it to obtain graphitic carbon nitride.

[0039] The preparation method of graphene oxide is as follows:

[0040] With slight modifications to the Hummers method, 5 g of graphite powder was placed in a 2 L beaker and soaked overnight in 400 mL of concentrated sulfuric acid. The temperature was controlled below 5 °C in a water bath. 2.5 g of sodium nitrate was added, and the mixture was stirred until homogeneous. 15 g of potassium permanganate was slowly added, and the reaction solution temperature was controlled to not exceed 5 °C. After thorough mixing, the mixture was kept in a constant temperature water bath at 35 °C and stirred evenly for 2 hours. 230 mL of distilled water was added, and the reaction solution temperature was controlled at approximately 95 °C. Stirring continued for 15 minutes, followed by the addition of 700 mL of distilled water and 20 mL of 30% hydrogen peroxide. The solution changed from black to yellowish-brown, indicating the reaction was terminated. The mixture was filtered while hot, washed with 5% dilute hydrochloric acid, and dried in a 60 °C oven to obtain graphene oxide.

[0041] Scanning electron microscope images of the cobalt phthalocyanine-graphite phase carbon nitride / graphene ternary composite material obtained in this embodiment are shown below. Figure 2 As shown in the figure, the ternary composite material is a dispersed two-dimensional sheet structure.

[0042] In this embodiment, the cobalt phthalocyanine-graphite phase carbon nitride / graphene ternary composite material obtained was dispersed in water and allowed to stand for 2 hours before being compared with... Figure 4 As shown in the figure, the ternary composite material has better dispersibility in water compared to cobalt phthalocyanine.

[0043] The carbon dioxide gas adsorption curve of the cobalt phthalocyanine-graphite phase carbon nitride / graphene ternary composite material obtained in this embodiment is as follows: Figure 9 As shown in the figure, the ternary composite material has a large specific surface area.

[0044] The current-voltage characteristic curve of the cobalt phthalocyanine-graphite phase carbon nitride / graphene ternary composite material obtained in this embodiment is shown in the figure below. Figure 11 As shown in the figure, the ternary composite material has better electrical conductivity than cobalt phthalocyanine.

[0045] Implementation Method 2:

[0046] This embodiment describes the preparation of a cobalt phthalocyanine-graphite phase carbon nitride / graphene ternary composite material:

[0047] Step 1: Add 25 mg of cobalt phthalocyanine powder and 0.5 g of graphitic carbon nitride powder to 5 mL of 90% sulfuric acid solution. Seal and stir for 2 h at 90 °C. Cool to room temperature to obtain solution A.

[0048] Step 2: Under ice bath conditions, add 10 mg of sodium nitrite powder to solution A obtained in step 1 and stir for 1 hour to obtain solution B;

[0049] Step 3: Weigh 150 mg of graphene oxide powder and add it to 150 mL of distilled water. Disperse the powder by ultrasonication for 2 h to obtain solution C.

[0050] Step 4: At 25 °C, 1 mL of solution B obtained in step 2 is added dropwise to 150 mL of solution C obtained in step 3 within 2 minutes, stirred for 1 h, then 100 mg of ascorbic acid is added, and stirring is continued for 1 h. The product is separated by centrifugation, washed 3 to 5 times with distilled water and ethanol respectively, and dried at 80 °C to obtain the cobalt phthalocyanine-graphite phase carbon nitride / graphene ternary composite material.

[0051] Implementation Method 3:

[0052] This embodiment describes the preparation of a ternary composite material consisting of iron phthalocyanine, graphitic carbon nitride, and graphene.

[0053] Step 1: Add 50 mg of iron phthalocyanine powder and 1 g of graphitic carbon nitride powder to 8 mL of 95% sulfuric acid solution, seal and stir for 2 h at 110 ℃, cool to room temperature to obtain solution A;

[0054] Step 2: Under ice bath conditions, add 15 mg of sodium nitrite powder to solution A obtained in step 1 and stir for 1 hour to obtain solution B;

[0055] Step 3: Weigh 300 mg of graphene oxide powder and add it to 150 mL of distilled water. Disperse the powder by ultrasonication for 2 h to obtain solution C.

[0056] Step 4: At 25 °C, 3 mL of solution B obtained in step 2 is added dropwise to 150 mL of solution C obtained in step 3 within 2 minutes, stirred for 1 h, then 100 mg of ascorbic acid is added, and stirring is continued for 1 h. The product is separated by centrifugation, washed 3 to 5 times with distilled water and ethanol respectively, and dried at 80 °C to obtain the iron phthalocyanine-graphite phase carbon nitride / graphene ternary composite material.

[0057] Implementation Method 4:

[0058] This embodiment describes the preparation of a nickel phthalocyanine-graphite phase carbon nitride / graphene ternary composite material:

[0059] Step 1: Add 75 mg of nickel phthalocyanine powder and 0.5 g of graphitic carbon nitride powder to 5 mL of 98% sulfuric acid solution. Seal and stir at 90℃ for 2 h, then cool to room temperature to obtain solution A.

[0060] Step 2: Under ice bath conditions, add 10 mg of sodium nitrite powder to solution A obtained in step 1 and stir for 1 hour to obtain solution B;

[0061] Step 3: Weigh 150 mg of graphene oxide powder and add it to 150 mL of distilled water. Disperse the powder by ultrasonication for 2 h to obtain solution C.

[0062] Step 4: At 25 °C, 5 mL of solution B obtained in step 2 is added dropwise to 150 mL of solution C obtained in step 3 within 2 minutes, stirred for 1 h, then 100 mg of ascorbic acid is added, and stirring is continued for 1 h. The product is separated by centrifugation, washed 3 to 5 times with distilled water and ethanol respectively, and dried at 80 °C to obtain the metal phthalocyanine-graphite phase carbon nitride / graphene ternary composite material.

[0063] Implementation Method 5:

[0064] This embodiment describes the preparation of a ternary composite material consisting of iron phthalocyanine, graphitic carbon nitride, and graphene.

[0065] Step 1: Add 75 mg of iron phthalocyanine powder and 0.5 g of graphitic carbon nitride powder to 10 mL of 90% sulfuric acid solution. Seal and stir for 2 h at 90℃, then cool to room temperature to obtain solution A.

[0066] Step 2: Under ice bath conditions, add 10 mg of sodium nitrite powder to solution A obtained in step 1 and stir for 1 hour to obtain solution B;

[0067] Step 3: Weigh 150 mg of graphene oxide powder and add it to 150 mL of distilled water. Disperse the powder by ultrasonication for 2 h to obtain solution C.

[0068] Step 4: At 25 °C, 5 mL of solution B obtained in step 2 is added dropwise to 150 mL of solution C obtained in step 3 within 2 minutes, stirred for 1 h, then 100 mg of ascorbic acid is added, and stirring is continued for 1 h. The product is separated by centrifugation, washed 3 to 5 times with distilled water and ethanol respectively, and dried at 80 °C to obtain the iron phthalocyanine-graphite phase carbon nitride / graphene ternary composite material.

[0069] Implementation method 6:

[0070] This embodiment describes the preparation and testing of a metal phthalocyanine-graphite phase carbon nitride / graphene ternary composite electrode: The cobalt phthalocyanine-graphite phase carbon nitride / graphene ternary composite material obtained in Embodiment 1 was ground. 5 mg of the sample was weighed into a 2 mL centrifuge tube, and 30 μL of 5% Nafion solution and 70 μL of anhydrous ethanol were added. The sample tube was tightly capped and ultrasonically dispersed in an ultrasonic cleaner for 2 hours to obtain a uniformly dispersed catalyst ink.

[0071] The carbon paper was cut into 1×1 cm squares and washed sequentially in 5% dilute hydrochloric acid, distilled water, acetone, and ethanol. After drying, 100 μL of catalyst ink was evenly coated onto a carbon paper. After drying, the cobalt phthalocyanine-graphite phase carbon nitride / graphene ternary composite electrode was obtained.

[0072] A three-electrode system was formed, with the working electrode as the working electrode, a graphite rod as the counter electrode, and silver / silver chloride as the reference electrode. In a 0.5 mol / L potassium bicarbonate solution saturated with carbon dioxide, 20 cycles of cyclic voltammetry were performed with a potential window of -0.5 to -0.9 V vs. RHE and a scan rate of 50 mV / s to activate the working electrode. Chronostatic potentiometry was then performed at the corresponding potential. Samples were taken at 10 min for gas chromatography to detect the products, and the Faraday efficiency was calculated.

[0073] The Faradaic efficiency and current density of the cobalt phthalocyanine-graphite phase carbon nitride / graphene ternary composite electrode prepared in this embodiment for the electrocatalytic reduction of carbon dioxide to carbon monoxide are as follows: Figure 12 As shown in the figure, the composite material maintains high Faraday efficiency and high current density over a wide potential window.

Claims

1. A method for preparing a ternary composite material of metal phthalocyanine-graphite phase carbon nitride / graphene, characterized in that, Includes the following steps: Step 1: Add 25–125 mg of metal phthalocyanine powder and 0.5–1 g of graphitic carbon nitride powder to 5–10 mL of sulfuric acid solution with a concentration of 90–98%. Seal and stir for 2 h at 90–110 °C, then cool to room temperature to obtain solution A. Step 2: Under ice bath conditions, add 10-25 mg of sodium nitrite powder to solution A obtained in step 1 and stir for 1 hour to obtain solution B; Step 3: Weigh 150–450 mg of graphene oxide powder and add it to 150 mL of distilled water. Disperse the powder by sonication for 2 h to obtain solution C. Step 4: At 25 °C, 1–5 mL of solution B obtained in Step 2 is added dropwise to 150 mL of solution C obtained in Step 3 within 2 minutes, stirred for 1 h, then 100 mg of ascorbic acid is added, and stirring is continued for 1 h. The product is separated by centrifugation, washed 3–5 times with distilled water and ethanol respectively, and dried at 80 °C to obtain a metal phthalocyanine-graphite phase carbon nitride / graphene ternary composite material; the metal in the metal phthalocyanine is cobalt, nickel or iron.

2. The preparation method of the metal phthalocyanine-graphite phase carbon nitride / graphene ternary composite material according to claim 1, characterized in that... The graphene oxide was prepared using the Hummers method.

3. The preparation method of the metal phthalocyanine-graphite phase carbon nitride / graphene ternary composite material according to claim 1, characterized in that... The ice bath temperature in step two is 0–5 °C.

4. The preparation method of the metal phthalocyanine-graphite phase carbon nitride / graphene ternary composite material according to claim 1, characterized in that... In step three, the ultrasonic power is 200 W and the ultrasonic frequency is 40 kHz.

5. The preparation method of the metal phthalocyanine-graphite phase carbon nitride / graphene ternary composite material according to claim 1, characterized in that... In step four, the centrifugation speed is 5000-8000 rpm.

6. The method for preparing the metal phthalocyanine-graphite phase carbon nitride / graphene ternary composite material according to claim 1, characterized in that... The stirring speed in steps one, two, and four is 1000 rpm.

7. A ternary composite material of metal phthalocyanine-graphite phase carbon nitride / graphene, characterized in that, The ternary composite material is prepared by the preparation method described in any one of claims 1 to 6.

8. An electrocatalyst, characterized in that, The electrocatalyst is the metal phthalocyanine-graphite phase carbon nitride / graphene ternary composite material according to claim 7, used for the electrocatalytic reduction of carbon dioxide.

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