C-tio 2 composite material using carbon source as raw material, preparation method therefor and use thereof

Abstract

Disclosed in the present invention are a C-TiO2 composite material using a carbon source as a raw material, a preparation method therefor and the use thereof. The preparation method comprises: dispersing a carbon source and TiO2 powder in a polar solvent to obtain a suspension A; heating the suspension A under a stirring condition, and volatilizing the polar solvent to obtain a mixture B; and calcining the mixture B to obtain a C-TiO2 composite material, wherein the carbon source comprises a first carbon source and / or a second carbon source, the first carbon source is elemental carbon, and the second carbon source is an organic matter that can be pyrolyzed to generate carbon. The present invention uses recycled or cheap carbon sources as raw materials to prepare the C-TiO2 composite material, which can effectively reduce environmental pollution caused by decommissioned new energy power lithium batteries while providing a feasible solution for the high-value utilization of cheap carbon sources. The C-TiO2 composite material is applied to the field of electrocatalytic water splitting to prepare efficient and stable oxygen evolution catalytic electrodes, thus realizing ampere-level current density applications oriented to industrial requirements.

Description

A C-TiO2 composite material using carbon source as raw material, its preparation method and application Technical Field

[0001] This invention belongs to the field of composite material technology, specifically relating to a C-TiO2 composite material using carbon source as raw material, its preparation method, and its application. Background Technology

[0002] Titanium dioxide possesses excellent chemical stability and electrochemical resistance, making it widely used in various energy conversion and storage materials. However, its high bandgap of 3.2 eV and low conductivity lead to increased interfacial contact impedance, hindering its application in electrochemical devices. One research direction to improve the conductivity of titanium dioxide is combining it with highly conductive carbon materials. For example, invention patent CN201810191246X discloses a GO-TiO2 nanorod composite nanoparticle and its preparation method, wherein the GO particles (redox graphene) are prepared by redox method, and the TiO2 nanorods are grown on the surface of sheet-like GO by electrochemical and chemical bath deposition methods; invention patent CN2022108599970 discloses a titanium dioxide electrode coated with oxygen-defect-containing nano-carbon layer and its preparation method and magnesium battery, wherein the nano-carbon layer is formed by impregnating nanorods with a mixed solution of dopamine hydrochloride and tris(hydroxymethyl)aminomethane and then calcining and carbonizing them. However, carbon sources such as dopamine hydrochloride and redox graphene are expensive, and the production cost of composite materials formed by titanium dioxide and carbon materials is high, which hinders the low-cost large-scale application of related processes.

[0003] Therefore, using inexpensive carbon sources to modify titanium dioxide materials can bring huge economic and social benefits.

[0004] Furthermore, titanium dioxide possesses a tunable band structure and excellent light-harvesting ability, making it a promising photocatalyst with significant application potential in photocatalytic water splitting for hydrogen production. However, photocatalytic hydrogen production is limited by unstable environmental factors, making it difficult to sustain and stabilize. Electrocatalytic water splitting for hydrogen production, based on electricity, is considered a highly promising method for green hydrogen production. However, titanium dioxide exhibits electrocatalytic inertness, making it difficult to apply in electrocatalytic water splitting despite its suitability for photocatalytic hydrogen production. Using titanium dioxide as a supported catalyst is one current research approach for its application in water electrolysis for hydrogen production. For example, invention patent CN2021105760082 discloses a supported RuO2 catalyst. x / F-TiO2 oxygen evolution catalyst is used for the slow-kind oxygen evolution half-reaction in electrocatalytic water splitting, where TiO2 is used as a highly efficient support. Invention patent CN2021112724521 discloses a supported iridium catalyst, in which metallic iridium is supported on a titanium dioxide support, for catalyzing the anodic oxygen evolution reaction in the water electrolysis process.

[0005] Therefore, in existing technologies, titanium dioxide is generally used as a carrier for catalytically active materials to reduce the amount of precious metal catalysts used and lower catalyst production costs. However, the catalysts obtained through these methods are all powdered catalysts, which have weak bonding with the conductive substrate. In industrial-scale ampere-level electrocatalytic water splitting, the large-scale escape of bubbles continuously impacts the catalyst-conductive substrate interface of the electrode, causing catalyst detachment and resulting in electrode activity degradation. Currently available titanium dioxide powdered composite materials cannot achieve efficient and stable ampere-level electrocatalytic water splitting applications, which greatly limits the large-scale application of titanium dioxide materials in electrochemical green hydrogen production.

[0006] In conclusion, if titanium dioxide-modified materials can be prepared using inexpensive carbon sources, and new application methods can be developed to enable these materials to be directly used in electrocatalytic water splitting for hydrogen production, the production cost of this process can be reduced. Summary of the Invention

[0007] To address the aforementioned technical problems, the present invention aims to provide a C-TiO2 composite material using a carbon source as raw material, its preparation method, and its application. The preparation of C-TiO2 composite material using an inexpensive carbon source can effectively reduce the environmental pollution caused by retired power lithium batteries from new energy sources, while also providing a feasible solution for the high-value utilization of inexpensive carbon sources.

[0008] Another objective of this invention is to provide an application method for the C-TiO2 composite material prepared above, proposing a "chloride ion-assisted micro-battery corrosion" strategy to apply the C-TiO2 composite material in the field of electrocatalytic water splitting, thereby preparing a highly efficient and stable oxygen evolution catalytic electrode that can achieve ampere-level current density applications for industrial applications.

[0009] To achieve the above-mentioned objectives, the technical solution adopted by the present invention is as follows:

[0010] In a first aspect, the present invention provides a method for preparing a C-TiO2 composite material using a carbon source as raw material, as follows:

[0011] A1. Disperse the carbon source and TiO2 powder in a polar solvent to obtain suspension A;

[0012] A2. Under stirring conditions, suspension A is heated to evaporate the ethanol aqueous solution, resulting in mixture B.

[0013] A3. Calcine mixture B to obtain C-TiO2 composite material;

[0014] The carbon source includes one or both of the first carbon source and the second carbon source. The first carbon source is elemental carbon, and the second carbon source is an organic matter that can be decomposed to produce carbon.

[0015] Preferably, the first carbon source includes recycled conductive carbon material; more preferably, the first carbon source includes negative electrode graphite recovered from retired power lithium batteries; the second carbon source includes one or more of urea, citric acid, and glucose.

[0016] Preferably, in step A1, a chloride ion source is also added. The polar solvent is a solvent that can dissolve the chloride ion source and organic matter. The carbon source, TiO2 powder and chloride ion source are dispersed in the polar solvent to form suspension A. The chloride ion source includes one or both of sodium chloride and potassium chloride.

[0017] In step A1, the mass ratio of carbon source, TiO2 powder and chloride ion source is (0.2-10):1:(0-1).

[0018] More preferably, the polar solvent includes an aqueous ethanol solution, the carbon source, TiO2 powder, chloride ion source, and the mass ratio of water to ethanol in the aqueous ethanol solution is (0.2-10):1:(0-1):(2-10):(2-10), and more preferably, the mass ratio of water to ethanol in the aqueous ethanol solution is 1:(0.5-4).

[0019] Preferably, in step A2, the heating temperature is 50–80°C and the heating time is 1–12 hours.

[0020] Preferably, in step A3, the calcination temperature is 80-600°C, the calcination time is 1-12 hours, and the calcination treatment is carried out in an oxygen-containing atmosphere or an inert atmosphere. Specifically, when the carbon source is the first carbon source, the calcination treatment is carried out in an oxygen-containing atmosphere or an inert atmosphere, and when the carbon source is the second carbon source, the calcination treatment is carried out in an inert atmosphere.

[0021] In a second aspect, the present invention provides a C-TiO2 composite material prepared by the above-described method. The C-TiO2 composite material is formed with carbon as a support and TiO2 primary particles loaded on the carbon support. Preferably, the particle size range of the TiO2 primary particles is 5 nm to 5 μm, and the particle size range of the carbon support is 5 to 100 μm.

[0022] In a third aspect, the present invention proposes an application of a C-TiO2 composite material, as follows:

[0023] B1. The prepared C-TiO2 composite material is dispersed in a polar solvent to obtain slurry C;

[0024] B2. Spray slurry C onto the surface of the iron-nickel alloy and dry it to obtain an oxygen evolution electrode;

[0025] B3. The prepared oxygen evolution electrode is used in the electrochemical water splitting process;

[0026] In step B1, when the C-TiO2 composite material does not contain a chloride ion source, step B1 also adds a chloride ion source dispersed in an aqueous ethanol solution; a polar solvent refers to a solvent that can dissolve both the chloride ion source and organic matter.

[0027] Preferably, in step B1, the mass ratio of C-TiO2 composite material to chloride ion source is (1-10):(0-20).

[0028] Preferably, in step B1, the polar solvent includes an aqueous ethanol solution, the chloride ion source includes one or both of sodium chloride and potassium chloride, and the mass ratio of the C-TiO2 composite material, the chloride ion source and water and ethanol in the aqueous ethanol solution is (1-10):(0-20):(40-400):(40-400). More preferably, the mass ratio of water to ethanol is 1:(0.5-4).

[0029] Preferably, in step B2, the spraying amount of slurry C is calculated based on the mass ratio of the C-TiO2 composite material to the area ratio of the iron-nickel alloy, and is 0.1–2.0 mg / cm². 2 .

[0030] Preferably, in step B2, the drying time is 0.2 to 12 hours. Beneficial effects:

[0031] This invention uses recycled or inexpensive carbon sources as raw materials and cleverly utilizes the defect sites on the surface of graphite recovered from the negative electrode of retired power lithium batteries to firmly anchor titanium dioxide powder; or it utilizes the cracking reaction of inexpensive carbon sources during high-temperature calcination to generate a carbon layer that is tightly bonded to titanium dioxide powder in situ. The process scheme of this invention achieves simple and efficient titanium dioxide material modification, with a short process flow, high reliability, and easy large-scale production.

[0032] This invention develops a new application for the recycling of graphite from the negative electrode of retired power lithium batteries. Graphite is used as a carbon source to prepare C-TiO2 composite materials, which are then applied to ampere-level electrochemical water splitting for industrial applications. This method can replace precious metals in traditional catalytic electrodes, has high economic value, and solves the problems of high pollution, low value, and difficulty in processing recycled graphite, thus demonstrating significant social benefits.

[0033] This invention successfully applies C-TiO2 composite materials to the field of electrocatalytic water splitting through a strategy of "chloride ion-assisted micro-cell corrosion." This induces the formation of a micro-galvanic cell between the C-TiO2 composite material and a conductive iron-nickel alloy substrate, further generating highly catalytically active materials that are tightly bonded to the substrate. The oxygen evolution catalytic electrode prepared in this way maintains excellent activity and stability even at high current densities, enabling ampere-level current density applications for industrial applications. Attached Figure Description

[0034] Figure 1 is a scanning electron microscope image of the recycled negative electrode graphite from a retired new energy power lithium battery in Example 1;

[0035] Figure 2 is a scanning electron microscope image of the nano-scale TiO2 powder in Example 1;

[0036] Figure 3 is a scanning electron microscope image of the C-TiO2 composite material in Example 1;

[0037] Figure 4 shows the X-ray photoelectron spectrum of the C-TiO2 composite material in Example 1;

[0038] Figure 5 shows the electrochemical oxygen evolution reaction activity test curve of the high-efficiency oxygen evolution electrode prepared by C-TiO2 composite material in Example 1;

[0039] Figure 6 is a scanning electron microscope image of the C-TiO2 composite material in Example 2;

[0040] Figure 7 shows the electrochemical oxygen evolution reaction activity test curve of the high-efficiency oxygen evolution electrode prepared by C-TiO2 composite material in Example 2;

[0041] Figure 8 is a scanning electron microscope image of the C-TiO2 composite material in Example 3;

[0042] Figure 9 shows the electrochemical oxygen evolution reaction activity test curve of the high-efficiency oxygen evolution electrode prepared by C-TiO2 composite material in Example 3;

[0043] Figure 10 is a scanning electron microscope image of the C-TiO2 composite material in Example 4;

[0044] Figure 11 shows the electrochemical oxygen evolution reaction activity test curve of the high-efficiency oxygen evolution electrode prepared by C-TiO2 composite material in Example 4;

[0045] Figure 12 shows the electrochemical oxygen evolution reaction activity test curve of the oxygen evolution electrode prepared by C-TiO2 composite material in Comparative Example 1;

[0046] Figure 13 shows the electrochemical oxygen evolution reaction activity test curve of the oxygen evolution electrode prepared by TiO2 material in Comparative Example 2. Detailed Implementation

[0047] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the specific implementation methods of the present invention will be described below with reference to the accompanying drawings. Obviously, the drawings described below are merely some embodiments of the present invention. For those skilled in the art, other drawings and other implementation methods can be obtained based on these drawings without any creative effort.

[0048] This invention proposes a C-TiO2 composite material using a carbon source as raw material. Carbon serves as the carrier, with TiO2 primary particles loaded onto the carbon carrier. The particle size of the TiO2 primary particles ranges from approximately 5 nm to 5 μm, while the particle size of the carbon carrier ranges from approximately 5 to 100 μm. The carbon carrier is sourced from inexpensive or recycled carbon sources. Recycled carbon sources include recycled graphite, such as the negative electrode graphite carbon recovered from retired power lithium batteries. Inexpensive carbon sources include low-cost sources such as urea, citric acid, and glucose. Using recycled carbon sources can also effectively reduce environmental pollution caused by retired power lithium batteries from new energy sources.

[0049] This invention also proposes a method for preparing C-TiO2 composite materials using carbon sources as raw materials, the steps of which are as follows:

[0050] A1. Disperse the carbon source and TiO2 powder in a polar solvent to obtain suspension A;

[0051] A2. Under stirring conditions, suspension A is heated to evaporate the polar solvent, resulting in mixture B;

[0052] A3. Calcine mixture B to obtain C-TiO2 composite material.

[0053] In step A1, the carbon source includes a first carbon source and a second carbon source. The first carbon source is elemental carbon, which includes recycled conductive carbon materials, such as recycled graphite. Recycled graphite can be negative electrode graphite recovered from retired power lithium batteries of new energy. It is easy to understand that recycled graphite can also be pure conductive carbon materials recovered from other fields, such as industrial production waste. Graphite electrodes used in the production process of steel plants, aluminum plants, silicon plants, etc., will be worn out after a period of use and become waste graphite electrodes. The second carbon source is an organic matter that can be decomposed to generate carbon. Inexpensive organic matter is preferred as an inexpensive carbon source, such as urea, citric acid, and glucose.

[0054] Long-term charge-discharge cycles result in numerous defects on the surface of the graphite recovered from the negative electrode of retired power lithium batteries. These defects can serve as strong anchoring points for titanium dioxide. Therefore, a stable C-TiO2 composite material can be obtained by a three-step processing method involving solvent dispersion and mixing, solvent evaporation under stirring and heating, and high-temperature calcination of the recovered graphite and titanium dioxide powder.

[0055] Inexpensive carbon sources such as urea, citric acid, and glucose can decompose under high-temperature conditions. Therefore, mixing these carbon sources with titanium dioxide powder and then calcining them at high temperatures can generate a carbon layer that is tightly bonded to titanium dioxide in situ, thereby obtaining a stable C-TiO2 composite material.

[0056] In step A1, a chloride ion source is also added, and the carbon source, TiO2 powder and chloride ion source are dispersed in a polar solvent to form suspension A, wherein the chloride ion source includes one or both of sodium chloride and potassium chloride.

[0057] In step A1, the TiO2 powder is nano-sized TiO2 powder and / or micro-sized TiO2 powder.

[0058] In step A1, the polar solvent refers to a solvent capable of dissolving both the chloride ion source and the organic matter; it can be a mixed solvent or a pure substance. Preferably, the polar solvent is an aqueous solution of ethanol. In addition, the polar solvent can also be water, an aqueous solution of a low-molecular-weight alcohol / ketone, such as an aqueous solution of ethylene glycol.

[0059] In step A1, the mass ratio of carbon source, TiO2 powder and chloride ion source is (0.2-10):1:(0-1).

[0060] In step A1, when the polar solvent is an aqueous ethanol solution, the mass ratio of water to ethanol in the carbon source, TiO2 powder, chloride ion source and aqueous ethanol solution is (0.2-10):1:(0-1):(2-10):(2-10).

[0061] In step A1, the mass ratio of water to ethanol in the ethanol-water solution can be 1:(0.5–4). The mass ratio of water to ethanol in the ethanol-water solution does not affect the preparation of the product, but it does affect the drying speed.

[0062] In step A2, the heating temperature is 50–80°C and the heating time is 1–12 hours. The heating can be performed directly in an air atmosphere.

[0063] In step A3, the calcination temperature is 80–600°C, the calcination time is 1–12 h, and the calcination is carried out in an oxygen-containing atmosphere or an inert atmosphere. The oxygen-containing atmosphere can be an air atmosphere, and the inert atmosphere can be a nitrogen atmosphere or an inert gas such as an argon atmosphere.

[0064] It is easy to understand that when the carbon source is elemental carbon, combustion of the carbon source must be avoided during calcination. Therefore, a temperature below the ignition point of elemental carbon or calcination in an oxygen-free, inert environment must be selected. For example, when the ignition point of elemental carbon is above 600°C (such as graphite), the calcination temperature range and calcination atmosphere of this invention can be used. When the ignition point of elemental carbon is between 600°C and 800°C, a temperature below that ignition point can be selected for calcination, or an inert atmosphere and a higher calcination temperature can be used. When the carbon source is organic matter, calcination needs to decompose and carbonize the organic matter. The calcination temperature must be greater than or equal to the temperature at which the organic matter decomposes and carbonizes, and calcination must be carried out in an inert atmosphere to avoid oxidation of the organic matter.

[0065] The typical morphology of the C-TiO2 composite material prepared by the above preparation method is that of TiO2 particles loaded on a bulk carbon support.

[0066] The C-TiO2 composite material obtained by this invention can be used in the field of energy conversion and storage, such as in the field of electrochemical water splitting. Specific applications are as follows:

[0067] B1. The prepared C-TiO2 composite material is dispersed with a chloride ion source in a polar solvent to obtain slurry C;

[0068] B2. Spray slurry C onto the surface of the iron-nickel alloy and dry it to obtain an oxygen evolution electrode;

[0069] B3. The prepared oxygen evolution electrode is used in the electrochemical water splitting process.

[0070] In step B1, the chloride ion source includes one or both of sodium chloride and potassium chloride. The presence of chloride ions in situ or externally added to the C-TiO2 composite material in the slurry C can disrupt the passivation film on the iron-nickel alloy surface, which is beneficial for the C-TiO2 composite material to adhere to the iron-nickel alloy surface.

[0071] In step B1, the polar solvent refers to a solvent capable of dissolving both the chloride ion source and the organic matter; it can be a mixed solvent or a pure substance. Preferably, the polar solvent is an aqueous solution of ethanol. In addition, the polar solvent can also be an aqueous solution of water or a low-molecular-weight alcohol / ketone, such as an aqueous solution of ethylene glycol.

[0072] In step B1, the mass ratio of C-TiO2 composite material to chloride ion source is (1-10):(0-20).

[0073] In step B1, the polar solvent is an aqueous ethanol solution. The mass ratio of the C-TiO2 composite material, the chloride ion source, and the water and ethanol in the aqueous ethanol solution is (1-10):(0-20):(40-400):(40-400). Preferably, the mass ratio of water to ethanol can be 1:(0.5-4). The mass ratio of water to ethanol in the aqueous ethanol solution does not affect the preparation of the product, but it does affect the drying speed.

[0074] In step B2, the main components of the iron-nickel alloy are iron and nickel, wherein the mass fraction of iron is 50-80% and the mass fraction of nickel is 20-50%. In this invention, iron-nickel alloy refers to an alloy material whose main elements are iron and nickel, and other metallic elements may also be incorporated.

[0075] In step B2, the spraying amount of slurry C is calculated based on the mass ratio of the C-TiO2 composite material to the area ratio of the iron-nickel alloy, and is 0.1–2.0 mg / cm². 2 That is, each square centimeter of iron-nickel alloy surface spray slurry contains 0.1 to 2.0 mg of C-TiO2 composite material.

[0076] In step B2, the drying time is 0.2 to 12 hours, and drying can be carried out in an air atmosphere.

[0077] It should be noted that in this invention, if a chloride ion source is added in the preparation step, then a chloride ion source may not be added in the application step; conversely, if a chloride ion source is not added in the preparation step, then a chloride ion source needs to be added in the application step.

[0078] The C-TiO2 composite material prepared by this invention can be used to prepare a high-efficiency oxygen evolution electrode. The principle is as follows: First, the presence of chloride ions in the slurry C, either precipitated in situ or added externally by the C-TiO2 composite material, will damage the passivation film on the surface of the conductive iron-nickel alloy, reducing the corrosion resistance of the iron-nickel alloy. Second, thanks to the enhanced conductivity of the C-TiO2 composite material and its potential difference with the iron-nickel alloy surface, the C-TiO2 composite material forms a large number of micro galvanic cells on the iron-nickel alloy surface. At this time, the iron-nickel alloy acts as the negative electrode of the micro galvanic cell, and iron-nickel ions are continuously precipitated. The C-TiO2 composite material acts as the positive electrode of the micro galvanic cell, and an oxygen reduction reaction occurs to generate hydroxide ions. Thus, at and around the solid-solid interface between the C-TiO2 composite material and the iron-nickel alloy, the precipitated iron-nickel ions combine with hydroxide ions to obtain a highly active iron-nickel hydroxide that is tightly bonded to the conductive substrate, serving as the catalytic active phase for the oxygen evolution reaction. This can achieve ampere-level current density applications for industrial applications.

[0079] The technical solution of the present invention will be described in detail below with specific embodiments.

[0080] Example 1

[0081] A1. By weight fraction, 2 parts of recycled negative electrode graphite from retired new energy power lithium batteries, 6 parts of nano-sized TiO2 powder, and 3 parts of potassium chloride are dispersed in 30 parts of water and 36 parts of anhydrous ethanol to obtain suspension A.

[0082] A2. Under stirring, suspension A is heated to obtain mixture B, wherein the heating temperature is 70℃, the heating time is 5h, and the heating environment is an air environment;

[0083] A3. The mixture B is calcined to obtain the C-TiO2 composite material, wherein the calcination temperature is 100℃, the calcination time is 8h, and the calcination environment is an air environment.

[0084] B1. By weight fraction, 3 parts of C-TiO2 composite material and 1 part of potassium chloride are dispersed in a mixed solution of 250 parts of water and 250 parts of ethanol to obtain slurry C;

[0085] B2. Based on the mass ratio of C-TiO2 composite material to the area of ​​the iron-nickel alloy, slurry C is sprayed onto the surface of the iron-nickel alloy (the alloy contains approximately 40% iron and 60% nickel by mass), with a spraying amount of 0.4 mg / cm². 2 ;

[0086] The iron-nickel alloy coated with slurry C was left to air dry for 2 hours to obtain a high-efficiency oxygen evolution electrode.

[0087] Figure 1 shows a scanning electron microscope image of the recycled negative electrode graphite from retired new energy power lithium batteries. The recycled negative electrode graphite exhibits a blocky structure at the micrometer scale (10-50 μm).

[0088] Figure 2 shows a scanning electron microscope image of nanoscale TiO2 powder. The nanoscale TiO2 powder contains a large number of primary nanoscale particles, which agglomerate into secondary particles at the micrometer scale (0.5–3 μm). In this embodiment, recycled graphite from a lithium-ion battery anode is used as the carbon source, and the nanoscale TiO2 powder is modified according to the steps described above.

[0089] Figure 3 shows a scanning electron microscope image of the obtained C-TiO2 composite material. The surface of the bulk recycled negative electrode graphite is loaded with a large amount of nano-sized TiO2 powder. The introduction of highly conductive recycled negative electrode graphite can effectively improve the conductivity of nano-sized TiO2 materials and promote their application in electrochemical devices.

[0090] Figure 4 shows the X-ray photoelectron spectroscopy (XPS) spectrum of the C-TiO2 composite material. The detection of K and Cl elements indicates that the potassium chloride introduced during the preparation process was successfully retained in the C-TiO2 composite material. During the preparation of a high-efficiency oxygen evolution electrode induced by the C-TiO2 composite material, chloride ions present in the slurry, either precipitated in situ or added externally, can damage the passivation film on the conductive iron-nickel alloy surface, reducing the corrosion resistance of the iron-nickel alloy. Simultaneously, thanks to the enhanced conductivity of the C-TiO2 composite material and its potential difference with the iron-nickel alloy surface, the C-TiO2 composite material forms numerous micro-galvanic cells on the iron-nickel alloy surface. At this point, the iron-nickel alloy acts as the negative electrode of the micro-galvanic cells, continuously precipitating iron-nickel ions, while the C-TiO2 composite material acts as the positive electrode, undergoing an oxygen reduction reaction to generate hydroxide ions. Thus, at and around the solid-solid interface between the C-TiO2 composite material and the iron-nickel alloy, the precipitated iron-nickel ions combine with hydroxide ions to obtain a highly active iron-nickel hydroxide that is tightly bonded to the conductive substrate, serving as the catalytic active phase for the oxygen evolution reaction.

[0091] A three-electrode testing system was employed, using the high-efficiency oxygen evolution electrode induced by C-TiO2 composite material in this embodiment as the working electrode, a platinum sheet as the counter electrode, mercury oxide as the reference electrode, and 1 mol / L potassium hydroxide as the electrolyte. Linear sweep voltammetry was performed using a Gamry Interface 1000 electrochemical workstation to characterize the oxygen evolution reaction activity of the working electrode. Specific test parameters were as follows: scan rate of 5 mV / s, scan voltage range of 1.2–1.65 V (vs. RHE, relative to the reversible hydrogen electrode). The test results are shown in Figure 5. The iron-nickel alloy with C-TiO2 composite material on its surface exhibited significantly enhanced electrocatalytic activity, reaching a current density of 100 mA / cm². 2 The overpotential is only 274 mV, less than the 363 mV of the iron-nickel alloy. Furthermore, at an overpotential of 352 mV, the high-efficiency oxygen evolution electrode induced by the C-TiO2 composite material in this embodiment can also generate an ampere-level current density (1000 mA / cm²) required for industrial applications. 2 ).

[0092] Example 2

[0093] A1. By weight fraction, 3 parts of recycled negative electrode graphite from retired new energy power lithium batteries, 5 parts of micron-sized TiO2 powder, and 0 parts of sodium chloride are dispersed in 30 parts of water and 40 parts of anhydrous ethanol to obtain suspension A.

[0094] A2. Under stirring, suspension A is heated to obtain mixture B, wherein the heating temperature is 60℃, the heating time is 10h, and the heating environment is an air environment;

[0095] A3. The mixture B was calcined to obtain the C-TiO2 composite material, wherein the calcination temperature was 400℃, the calcination time was 1h, and the calcination environment was an air environment;

[0096] B1. By weight fraction, 3 parts of C-TiO2 composite material and 4 parts of sodium chloride are dispersed in a mixed solution of 230 parts of water and 280 parts of ethanol to obtain slurry C;

[0097] B2. Based on the mass ratio of C-TiO2 composite material to the area of ​​the iron-nickel alloy, slurry C is sprayed onto the surface of the iron-nickel alloy (the alloy contains approximately 40% iron and 60% nickel by mass), with a spraying amount of 0.6 mg / cm². 2 ;

[0098] The iron-nickel alloy coated with slurry C was left to air dry for 6 hours to obtain a high-efficiency oxygen evolution electrode.

[0099] Figure 6 shows a scanning electron microscope (SEM) image of the C-TiO2 composite material obtained in this embodiment using recycled negative electrode graphite from retired new energy power lithium batteries as the carbon source. The surface of the blocky recycled negative electrode graphite is loaded with a large amount of TiO2 powder. The introduction of highly conductive recycled negative electrode graphite can effectively improve the conductivity of TiO2 materials and promote their application in electrochemical devices.

[0100] In this embodiment, the process and reaction activity test of the C-TiO2 composite material-induced preparation of the high-efficiency oxygen evolution electrode are similar to those in Example 1. As shown in Figure 7, the iron-nickel alloy with the C-TiO2 composite material on its surface exhibits significantly enhanced electrocatalytic activity, reaching a current density of 100 mA / cm². 2 The overpotential is only 283 mV, less than the 363 mV of the iron-nickel alloy. Furthermore, at an overpotential of 362 mV, the high-efficiency oxygen evolution electrode induced by the C-TiO2 composite material in this embodiment can also generate an ampere-level current density (1000 mA / cm²) required for industrial applications. 2 ).

[0101] Example 3

[0102] A1. By weight fraction, 15 parts of urea, 6 parts of nano-sized TiO2 powder, and 3 parts of potassium chloride are dispersed in 35 parts of water and 40 parts of anhydrous ethanol to obtain suspension A.

[0103] A2. Under stirring, suspension A is heated to obtain mixture B, wherein the heating temperature is 65℃, the heating time is 12h, and the heating environment is an air environment;

[0104] A3. The mixture B was calcined to obtain the C-TiO2 composite material, wherein the calcination temperature was 500℃, the calcination time was 3h, and the calcination environment was a nitrogen atmosphere;

[0105] B1. By weight fraction, 1 part of C-TiO2 composite material and 0 parts of potassium chloride are dispersed in a mixed solution of 50 parts of water and 50 parts of ethanol to obtain slurry C;

[0106] B2. Based on the mass ratio of C-TiO2 composite material to the area of ​​the iron-nickel alloy, slurry C is sprayed onto the surface of the iron-nickel alloy (the alloy contains approximately 40% iron and 60% nickel by mass), with a spraying amount of 0.8 mg / cm². 2 ;

[0107] The iron-nickel alloy coated with slurry C was left to air dry for 8 hours to obtain a high-efficiency oxygen evolution electrode.

[0108] Figure 8 shows a scanning electron microscope (SEM) image of the C-TiO2 composite material obtained using urea as the carbon source in this embodiment. The surface of the blocky urea pyrolysis carbon is loaded with a large amount of TiO2 powder. The introduction of highly conductive urea pyrolysis carbon can effectively improve the conductivity of TiO2 materials and promote their application in electrochemical devices.

[0109] In this embodiment, the process and reaction activity test of the C-TiO2 composite material-induced preparation of the high-efficiency oxygen evolution electrode are similar to those in Example 1. As shown in Figure 9, the iron-nickel alloy with the C-TiO2 composite material on its surface exhibits significantly enhanced electrocatalytic activity, reaching a current density of 100 mA / cm². 2 The overpotential is only 273 mV, less than the 363 mV of the iron-nickel alloy. Furthermore, at an overpotential of 349 mV, the high-efficiency oxygen evolution electrode induced by the C-TiO2 composite material in this embodiment can also generate an ampere-level current density (1000 mA / cm²) required for industrial applications. 2 ).

[0110] Example 4

[0111] A1. By weight fraction, 16 parts of citric acid, 5 parts of micron-sized TiO2 powder, and 1 part of sodium chloride are dispersed in 30 parts of water and 35 parts of anhydrous ethanol to obtain suspension A.

[0112] A2. Under stirring, suspension A is heated to obtain mixture B, wherein the heating temperature is 80℃, the heating time is 4h, and the heating environment is an air environment;

[0113] A3. Calcine mixture B to obtain C-TiO2 composite material, wherein the calcination temperature is 600℃, the calcination time is 2h, and the calcination environment is argon atmosphere;

[0114] B1. By weight fraction, 3 parts of C-TiO2 composite material and 2 parts of sodium chloride are dispersed in a mixed solution of 250 parts of water and 250 parts of ethanol to obtain slurry C;

[0115] B2. Based on the mass ratio of C-TiO2 composite material to the area of ​​the iron-nickel alloy, slurry C is sprayed onto the surface of the iron-nickel alloy (the alloy contains approximately 40% iron and 60% nickel by mass) at a coating weight of 1.2 mg / cm². 2 ;

[0116] The iron-nickel alloy coated with slurry C was left to air dry for 12 hours to obtain a high-efficiency oxygen evolution electrode.

[0117] Figure 10 shows a scanning electron microscope (SEM) image of the C-TiO2 composite material obtained using citric acid as the carbon source in this embodiment. The surface of the blocky citric acid pyrolysis carbon is loaded with a large amount of TiO2 powder. The introduction of highly conductive citric acid pyrolysis carbon can effectively improve the conductivity of TiO2 materials and promote their application in electrochemical devices.

[0118] In this embodiment, the process and reaction activity test of the C-TiO2 composite material-induced preparation of the high-efficiency oxygen evolution electrode are similar to those in Example 1. As shown in Figure 11, the iron-nickel alloy with the C-TiO2 composite material on its surface exhibits significantly enhanced electrocatalytic activity, reaching a current density of 100 mA / cm². 2 The overpotential is only 290mV, less than the 363mV of the iron-nickel alloy. Furthermore, at an overpotential of 378mV, the high-efficiency oxygen evolution electrode induced by the C-TiO2 composite material in this embodiment can also generate an ampere-level current density (1000mA / cm²) required for industrial applications. 2 ).

[0119] Comparative Example 1

[0120] A1. By weight fraction, 2 parts of recycled negative electrode graphite from retired new energy power lithium batteries, 6 parts of nano-sized TiO2 powder, and 3 parts of potassium chloride are dispersed in 30 parts of water and 36 parts of anhydrous ethanol to obtain suspension A.

[0121] A2. Under stirring, suspension A is heated to obtain mixture B, wherein the heating temperature is 70℃, the heating time is 5h, and the heating environment is atmospheric environment;

[0122] A3. The mixture B was calcined to obtain the C-TiO2 composite material, wherein the calcination temperature was 100℃, the calcination time was 8h, and the calcination environment was an air environment;

[0123] B1. By weight fraction, 3 parts of C-TiO2 composite material and 1 part of potassium chloride are dispersed in a mixed solution of 250 parts of water and 250 parts of ethanol to obtain suspension C;

[0124] B2. Based on the mass ratio of the C-TiO2 composite material to the carbon cloth area, the suspension C is sprayed onto the carbon cloth surface at a spraying amount of 0.4 mg / cm². 2 ;

[0125] The carbon cloth coated with suspension C was left to air dry for 2 hours to obtain the oxygen evolution electrode.

[0126] The preparation method of the C-TiO2 composite material in this comparative example is the same as that in Example 1. In the step of inducing the preparation of the oxygen evolution electrode with the C-TiO2 composite material, carbon cloth is used instead of the iron-nickel alloy.

[0127] A three-electrode testing system was employed, using the oxygen evolution reaction (OER) electrode induced by the C-TiO2 composite material in this comparative example as the working electrode, a platinum sheet as the counter electrode, mercury oxide as the reference electrode, and 1 mol / L potassium hydroxide as the electrolyte. Linear sweep voltammetry was performed using a Gamry Interface 1000 electrochemical workstation to characterize the OER activity of the working electrode. Specific test parameters were as follows: scan rate of 5 mV / s, scan voltage range of 1.2–1.65 V (vs. RHE, relative to the reversible hydrogen electrode). The test results are shown in Figure 12. The carbon cloth with the C-TiO2 composite material on its surface showed no significant current response to the OER reaction even at high voltages. Comparison with the results of Example 1 indicates that the key to applying the C-TiO2 composite material in the field of electrochemical water splitting lies in loading it onto the surface of an iron-nickel alloy, utilizing the micro-galvanic cell formed by the solid-solid interface potential difference between the two to obtain a highly active iron-nickel hydroxide tightly bonded to the conductive substrate as the catalytic active phase for the OER reaction.

[0128] Comparative Example 2

[0129] A1. By weight fraction, 6 parts of nano-sized TiO2 powder and 3 parts of potassium chloride are dispersed in 30 parts of water and 36 parts of anhydrous ethanol to obtain suspension A;

[0130] A2. Under stirring, suspension A is heated to obtain mixture B, wherein the heating temperature is 70℃, the heating time is 5h, and the heating environment is an air environment;

[0131] A3. The mixture B is calcined to obtain TiO2 material, wherein the calcination temperature is 100℃, the calcination time is 8h, and the calcination environment is an air environment;

[0132] B1. By weight fraction, 3 parts of TiO2 material and 1 part of potassium chloride are dispersed in a mixed solution of 250 parts of water and 250 parts of ethanol to obtain suspension C.

[0133] B2. Based on the mass ratio of TiO2 material to the area of ​​the iron-nickel alloy, spray suspension C onto the surface of the iron-nickel alloy (the alloy contains approximately 40% iron and 60% nickel by mass) at a spraying amount of 0.4 mg / cm². 2 ;

[0134] The iron-nickel alloy coated with suspension C was left to air dry for 2 hours to obtain an oxygen evolution electrode.

[0135] The preparation method of the TiO2 material in this comparative example is similar to that in Example 1, but recycled graphite from retired new energy power lithium batteries is not added as a carbon source. The application method of the TiO2 composite material in this comparative example is the same as that in Example 1.

[0136] A three-electrode testing system was used, with the oxygen evolution reaction (OER) electrode induced by TiO2 material in this comparative example as the working electrode, a platinum sheet as the counter electrode, mercury oxide as the reference electrode, and 1 mol / L potassium hydroxide as the electrolyte. Linear sweep voltammetry was performed using a Gamry Interface 1000 electrochemical workstation to characterize the OER activity of the working electrode. Specific test parameters were as follows: scan rate of 5 mV / s, scan voltage range of 1.2–1.65 V (vs. RHE, relative to the reversible hydrogen electrode). The test results are shown in Figure 13. The iron-nickel alloy with TiO2 material on the surface showed limited improvement in electrocatalytic activity, especially when the current density reached 100 mA / cm². 2 The overpotential was 349 mV, only slightly better than the 363 mV of the iron-nickel alloy, and still insufficient to meet the ampere-level current density requirements for industrial applications. Comparison with the results of Example 1 demonstrates the importance of recovering graphite carbon from the negative electrode of retired new energy power lithium batteries. Unmodified TiO2, due to its low conductivity, hinders the formation of a solid-solid interface micro-galvanic cell between it and the iron-nickel alloy, resulting in limited improvement in the catalytic activity of the obtained oxygen evolution electrode.

[0137] The embodiments provided by the present invention have been described in detail above. Specific examples have been used to illustrate the principles and implementation methods of the present invention, and the descriptions of the embodiments above are only for the purpose of helping to understand the core ideas of the present invention. It should be noted that those skilled in the art can make several improvements and modifications to the present invention without departing from the principles of the present invention, and these improvements and modifications also fall within the protection scope of the claims of the present invention.

Claims

1. A method for preparing C-TiO2 composite material using carbon source as raw material, characterized in that, as follows: A1. Disperse the carbon source and TiO2 powder in a polar solvent to obtain suspension A; A2. Under stirring conditions, suspension A is heated to evaporate the polar solvent, resulting in mixture B; A3. Calcine mixture B to obtain C-TiO2 composite material; The carbon source includes one or both of the first carbon source and the second carbon source. The first carbon source is elemental carbon, and the second carbon source is an organic matter that can be decomposed to produce carbon.

2. The preparation method according to claim 1, characterized in that, In step A1, a chloride ion source is also added. A polar solvent is a solvent that can dissolve chloride ion source and organic matter. The carbon source, TiO2 powder and chloride ion source are dispersed in a polar solvent to form suspension A. The chloride ion source includes one or both of sodium chloride and potassium chloride. In step A1, the mass ratio of carbon source, TiO2 powder and chloride ion source is (0.2-10):1:(0-1).

3. The preparation method according to claim 2, characterized in that, Polar solvents include aqueous ethanol solution, carbon source, TiO2 powder, chloride ion source, and the mass ratio of water to ethanol in aqueous ethanol solution is (0.2~10):1:(0~1):(2~10):(2~10).

4. The preparation method according to claim 2 or 3, characterized in that, The first carbon source includes recycled conductive carbon material, more preferably, the first carbon source includes negative electrode graphite recovered from retired power lithium batteries; the second carbon source includes one or more of urea, citric acid and glucose.

5. The preparation method according to claim 2 or 3, characterized in that, In step A2, the heat treatment temperature is 50–80°C; In step A3, the calcination temperature is 80-600℃. When the carbon source is the first carbon source, the calcination is carried out in an oxygen-containing atmosphere or an inert atmosphere. When the carbon source is the second carbon source, the calcination is carried out in an inert atmosphere.

6. A C-TiO2 composite material, characterized in that, The C-TiO2 composite material is prepared by the preparation method according to any one of claims 2-5, wherein the C-TiO2 composite material is formed with carbon as a carrier and TiO2 particles loaded on the carbon carrier.

7. An application of a C-TiO2 composite material, characterized in that, as follows: B1. Disperse the C-TiO2 composite material prepared by any one of claims 2-5 in a polar solvent to obtain slurry C; B2. Spray slurry C onto the surface of the iron-nickel alloy and dry it to obtain an oxygen evolution electrode; B3. The prepared oxygen evolution electrode is used in the electrochemical water splitting process; In step B1, when the C-TiO2 composite material does not contain a chloride ion source, step B1 also involves adding a chloride ion source dispersed in a polar solvent.

8. The application according to claim 7, characterized in that, In step B1, the chloride ion source includes one or both of sodium chloride and potassium chloride, and the mass ratio of C-TiO2 composite material to chloride ion source is (1-10):(0-20).

9. The application according to claim 8, characterized in that, In step B1, the polar solvent includes an aqueous ethanol solution, and the mass ratio of the C-TiO2 composite material, the chloride ion source, and water and ethanol in the aqueous ethanol solution is (1-10):(0-20):(40-400):(40-400).

10. The application according to any one of claims 7-9, characterized in that, In step B2, the spraying amount of slurry C is calculated based on the mass ratio of the C-TiO2 composite material to the area ratio of the iron-nickel alloy, and is 0.1–2.0 mg / cm². 2 .

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