A CeO2-Co3O4 composite gel material and its preparation method
Patent Information
- Application Number
- CN202611121315.0
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2026-07-27
- Publication Date
- 2026-11-03
AI Technical Summary
Existing cerium dioxide-based composite gel materials suffer from insufficient visible light response, easy recombination of photogenerated carriers, high resistance to charge transport at heterogeneous interfaces, and insufficient exposure of active sites, resulting in low charge separation efficiency.
Using cerium nitrate, citric acid, potassium chloride, red mud, and sulfur-containing Co3O4 precursor as raw materials, a Ce-Co composite was obtained through mixing, grinding, and calcination. This composite was then introduced into a gelation system composed of acrylic acid, glycerol, N'N-methylenebisacrylamide, ammonium bicarbonate, and sodium bicarbonate. Through heating and aging, a three-phase heterogeneous interface consisting of a red mud-derived phase, a sulfur-doped CeO2 phase, and a Co3O4 phase was formed, constructing a hierarchical pore structure of macropores, mesopores, and micropores, which enhances visible light response and promotes carrier separation and transport.
It significantly improves the charge separation efficiency of the material, enhances the visible light response, promotes the spatial separation and transport of photogenerated carriers, fully exposes active sites, and improves the mass transfer efficiency of reactants.
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Figure CN123024546A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of composite gel material preparation technology, specifically to a CeO2-Co3O4 composite gel material and its preparation method. Background Technology
[0002] Photocatalysis, with its mild reaction conditions and environmental friendliness, is considered a core green solution to address environmental pollution and energy shortages. Cerium dioxide (CeO2), due to its excellent oxygen storage and release capacity and chemical stability, is a highly promising photocatalytic matrix material. Constructing composite gel materials using cerium dioxide as a matrix can leverage the high specific surface area and porous nature of gel systems to further enhance the exposure of active sites and reactant mass transfer efficiency, representing an important development direction in the field of photocatalytic materials. However, the low charge separation efficiency of existing cerium dioxide-based composite gel materials severely limits their practical application.
[0003] The main reasons for the low charge separation efficiency are as follows: First, cerium dioxide has a band gap of approximately 3.2 eV, which only responds to ultraviolet light with wavelengths less than 387 nm, resulting in extremely low visible light utilization and insufficient generation of photogenerated carriers. Second, photogenerated electrons and holes in cerium dioxide recombine rapidly in both the bulk and surface phases, leading to a high recombination rate and a very low proportion of carriers participating in surface reactions. Third, existing strategies for constructing heterojunctions with narrow-bandgap semiconductors such as cobalt tetroxide often use pure-phase raw materials, and the interfaces are mostly physical contacts, lacking chemical bonding bridging channels, resulting in high transport resistance of photogenerated carriers at the interface. Fourth, metal ions in the precursors of composite gel materials tend to aggregate, and existing pore-forming methods are limited, making it difficult to construct interconnected hierarchical channels in the gel system. This results in insufficient surface active sites, making it difficult for photogenerated carriers reaching the material surface to be effectively captured and utilized by reactants. All these factors contribute to the overall low charge separation efficiency of cerium dioxide-based composite gel materials.
[0004] Therefore, overcoming the shortcomings of existing cerium dioxide-based composite gel materials, such as insufficient visible light response, easy recombination of photogenerated carriers, large charge transport resistance at heterogeneous interfaces, and insufficient exposure of active sites, and thus improving the charge separation efficiency of the materials, has become a technical problem that urgently needs to be solved by those skilled in the art. Summary of the Invention
[0005] The purpose of this invention is to provide a CeO2-Co3O4 composite gel material and its preparation method, so as to overcome the problems of insufficient visible light response, easy recombination of photogenerated charge carriers, large charge transport resistance at heterogeneous interfaces, and insufficient exposure of active sites in the existing cerium dioxide-based composite gel materials, which lead to low charge separation efficiency.
[0006] The present invention solves the above-mentioned technical problems through the following technical solution: This invention provides a method for preparing a CeO2-Co3O4 composite gel material, comprising the following steps: Step 1: Mix and grind cerium nitrate, citric acid, potassium chloride, red mud and Co3O4 precursor containing sulfur source to obtain calcination precursor; Step 2: Calcine the precursor to obtain the Ce-Co complex; Step 3: Add acrylic acid and glycerol to deionized water and stir to obtain the first mixed solution. Weigh N'N-methylenebisacrylamide and add it to the first mixed solution and continue stirring to obtain the second mixed solution. Add ammonium bicarbonate to the second mixed solution and continue stirring to obtain the third mixed solution. Add the Ce-Co composite to the third mixed solution and continue stirring to obtain the fourth mixed solution. Add sodium bicarbonate to the fourth mixed solution, heat and purge with nitrogen gas, and after aging treatment, obtain the CeO2-Co3O4 composite gel material.
[0007] A further improvement of this invention is that the preparation method of the Co3O4 precursor containing a sulfur source specifically includes the following steps: Step a: Add cobalt nitrate to deionized water and stir to obtain solution A; add thiourea, ammonium fluoride and urea to deionized water and stir to obtain solution B; Step b: Add solution B to solution A and stir until homogeneous. After heating and reacting, wash the solution alternately with deionized water and anhydrous ethanol, and then dry to obtain cobalt powder. Step c: Add cobalt powder to acid solution and stir, heat under reflux and pass argon gas through, then wash until neutral to obtain Co3O4 precursor containing sulfur source.
[0008] A further improvement of the present invention is that, in step a, by mass parts, cobalt nitrate is 15-20 parts, thiourea is 2.2-4.5 parts, ammonium fluoride is 25-45 parts, and urea is 3.5-6 parts.
[0009] A further improvement of the present invention is that, in step b, the heating reaction temperature is 120~150℃ and the heating time is 15~24h; the drying temperature is 75~85℃ and the drying time is 20~28h.
[0010] A further improvement of the present invention is that, in step c, the acid solution is a citric acid solution with a concentration of 0.2~0.3 mol / L, the reflux temperature is 90~120℃, and the time is 10~14h; the argon flow rate is 40~60mL / min.
[0011] A further improvement of the present invention is that, in step one, by mass parts, cerium nitrate is 5.5 to 7.2 parts, Co3O4 precursor is 0.8 to 1.4 parts, citric acid is 0.45 to 0.75 parts, potassium chloride is 10 to 15 parts, and red mud is 2.5 to 3 parts.
[0012] A further improvement of the present invention is that, in step two, the calcination temperature is 700~900℃, the time is 3~4h, and the heating rate is 8~12℃ / min.
[0013] A further improvement of the present invention is that, in step three, by mass parts, acrylic acid is 3-5 parts, glycerol is 3-5 parts, N'N-methylenebisacrylamide is 0.2-0.4 parts, sodium bicarbonate is 2-4 parts, and ammonium bicarbonate is 1 part.
[0014] A further improvement of the present invention is that, in step three, the heating temperature is 70~110℃, the heating time is 15~30min, and the nitrogen flow rate is 40~60mL / min; the aging treatment temperature is 20~30℃, and the aging time is 10~14h.
[0015] The present invention also provides a CeO2-Co3O4 composite gel material, which is prepared by the above-mentioned method for preparing CeO2-Co3O4 composite gel material. The CeO2-Co3O4 composite gel material forms a three-phase heterogeneous interface composed of a red mud-derived phase, a sulfur-doped CeO2 phase, and a Co3O4 phase.
[0016] Compared with the prior art, the positive and progressive effects of the present invention are as follows: The method for preparing CeO2-Co3O4 composite gel material provided by this invention involves releasing sulfur elements from a Co3O4 precursor containing a sulfur source during calcination, thereby doping CeO2 with S anions. -Partially replacing lattice oxygen introduces lattice strain and impurity energy levels into the CeO2 surface and near-surface regions, effectively narrowing the band gap and enabling the material to achieve visible light response. Simultaneously, the multiphase mineral components rich in red mud, such as Fe2O3, Al2O3, and SiO2, undergo in-situ solid-state reactions with S-CeO2 and Co3O4 during calcination, constructing a three-phase heterogeneous interface of red mud-derived phase / S-CeO2 / Co3O4. SiO2 and CeO2 condense to form Si-O-Ce covalent bonds, serving as charge transport bridging channels; Fe2O3 and Co3O4 form pn heterojunctions through band matching, promoting spatial separation of photogenerated carriers. Potassium chloride, during calcination, facilitates the formation of pn heterojunctions. Over-melting etching simultaneously induces lattice oxygen overflow, forming surface oxygen vacancy defects, and constructs interconnected multi-level channels through a dissolution-reprecipitation mechanism. Sodium bicarbonate decomposes and releases CO2 during subsequent gelation heating treatment, exerting a pore-forming effect. The two work together to form a hierarchical pore structure of macropores, mesopores, and micropores. The abundant carboxyl groups in acrylic acid in the gel system coordinate with Ce and Co metal ions to achieve molecular-level uniform dispersion of the precursor, ensuring high dispersion and full exposure of active components after calcination. This overcomes the defects of easy agglomeration of precursor metal ions and insufficient exposure of active sites in existing technologies. The combined effect of these technical features significantly improves the overall charge separation efficiency of the material.
[0017] Furthermore, the sulfur-containing Co3O4 precursor can serve as a sulfur source to achieve S anion doping of CeO2 during subsequent calcination. At the same time, it transforms into an active component of Co3O4 to participate in the construction of the three-phase heterogeneous interface. The introduction of ammonium fluoride can regulate the properties of the reaction system during the precursor synthesis process. The decomposition and gas release of urea during heating helps to control the morphology of the precursor. Thiourea serves as both a sulfur source and a ligand, ensuring the uniform distribution of sulfur in the precursor.
[0018] The CeO2-Co3O4 composite gel material provided by this invention has a three-phase heterogeneous interface consisting of a red mud-derived phase, a sulfur-doped CeO2 phase, and a Co3O4 phase. In this interface, the Si-O-Ce covalent bonds formed by the condensation of SiO2 and CeO2 in the red mud act as charge transport bridging channels, reducing interfacial charge transport resistance. The pn heterojunction formed by Fe2O3 and Co3O4 through band matching promotes spatial separation of photogenerated carriers. The Lewis acidic sites provided by Al2O3 enhance the surface adsorption and activation of reactant molecules. Simultaneously, the material possesses a hierarchical pore structure of macropores, mesopores, and micropores. Combined with the high specific surface area of the gel system, this fully exposes active sites, improving reactant mass transfer efficiency. The synergistic effect of these structural features significantly improves the material's visible light response, carrier separation efficiency, and surface reactivity, ultimately achieving an overall improvement in charge separation efficiency. Attached Figure Description
[0019] The accompanying drawings are provided to further understand the invention and constitute a part of this invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an improper limitation of the invention.
[0020] Figure 1 This is a simplified diagram of the preparation method of the CeO2-Co3O4 composite gel material proposed in this application; Figure 2 The graph shows the NH3 product test results of the CeO2-Co3O4 composite gel materials prepared in the examples and comparative examples. Detailed Implementation
[0021] To enable those skilled in the art to understand the features and effects of the present invention, the terms and expressions used in the specification and claims are explained and defined in general below. Unless otherwise specified, all technical and scientific terms used herein have the ordinary meaning understood by those skilled in the art regarding the present invention, and in case of conflict, the definitions in this specification shall prevail.
[0022] The theories or mechanisms described and disclosed herein, whether right or wrong, should not in any way limit the scope of the invention, that is, the contents of the invention can be implemented without being limited by any particular theory or mechanism.
[0023] In this document, all features defined by numerical ranges or percentage ranges, such as numerical values, quantities, contents, and concentrations, are for the sake of brevity and convenience only. Accordingly, descriptions of numerical ranges or percentage ranges should be considered as covering and specifically disclosing all possible sub-ranges and individual numerical values (including integers and fractions) within those ranges.
[0024] In this article, unless otherwise specified, “contains,” “includes,” “containing,” “has,” or similar terms cover the meanings of “composed of” and “mainly composed of,” for example, “A contains a” covers the meanings of “A contains a and others” and “A contains only a.”
[0025] For the sake of brevity, not all possible combinations of the technical features in each implementation scheme or embodiment are described herein. Therefore, as long as there is no contradiction in the combination of these technical features, the technical features in each implementation scheme or embodiment can be combined arbitrarily, and all possible combinations should be considered within the scope of this specification.
[0026] Existing cerium dioxide-based composite gel materials suffer from limited responsiveness to the ultraviolet region due to the wide bandgap of CeO2 (approximately 3.2 eV), resulting in low visible light utilization. Furthermore, the rapid recombination rate of photogenerated electrons and holes in both the bulk and surface phases leads to an extremely low proportion of charge carriers participating in surface reactions. Simultaneously, when composited with narrow-bandgap semiconductors such as Co3O4, the interfaces are primarily physical contacts, lacking chemically bonded bridging channels and exhibiting high charge transport resistance. In addition, metal ions in the precursor tend to aggregate, pore-forming methods are limited, making it difficult to construct interconnected hierarchical channels, and surface active sites are insufficient. These shortcomings collectively contribute to the material's low charge separation efficiency.
[0027] Based on the above background, this application provides a method for preparing a CeO2-Co3O4 composite gel material. The method uses cerium nitrate, citric acid, potassium chloride, red mud, and a Co3O4 precursor containing a sulfur source as raw materials. These materials are mixed, ground, and calcined to obtain a Ce-Co composite. This composite is then introduced into a gelation system composed of acrylic acid, glycerol, N'N-methylenebisacrylamide, ammonium bicarbonate, and sodium bicarbonate. Through heating and aging treatment, the CeO2-Co3O4 composite gel material is obtained. This method, through the synergistic effect of multiple mechanisms such as sulfur source introduction, utilization of multiphase mineral components from red mud, potassium chloride melt etching, and gel framework coordination dispersion, achieves in-situ coupling during a single calcination. This systematically improves the charge separation efficiency of the material from multiple dimensions, including enhanced visible light response, promoted carrier separation and transport, construction of hierarchical channels, and full exposure of active sites.
[0028] The technical solution of this application will be clearly and completely described below with reference to specific embodiments. The described embodiments are only some embodiments of this application, and not all embodiments. Based on the embodiments in this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.
[0029] The following examples use instruments and equipment conventional in the art. Experimental methods in the following examples, unless otherwise specified, are generally performed under standard conditions or as recommended by the manufacturer. All raw materials used in the following examples are conventional commercially available products with specifications in the art, unless otherwise stated.
[0030] See Figure 1 A method for preparing a CeO2-Co3O4 composite gel material, the specific steps of which are as follows: Step 1: Mix and grind cerium nitrate, citric acid, potassium chloride, red mud and Co3O4 precursor containing sulfur source to obtain calcination precursor.
[0031] Cerium nitrate serves as the cerium source, forming the CeO2 matrix during subsequent calcination. Citric acid acts as a complexing agent and fuel, facilitating initial mixing of components during grinding and aiding combustion during calcination. Potassium chloride, as a molten salt medium, melts during calcination to etch the product. Red mud, an industrial solid waste containing multiphase mineral components such as Fe2O3, Al2O3, and SiO2, is not simply an iron source or inert carrier, but rather a multifunctional mineral precursor participating in subsequent interfacial reactions. The Co3O4 precursor, containing a sulfur source, simultaneously provides a cobalt source for Co3O4 formation and a sulfur source for subsequent doping. Uniform mixing of all components is fundamental for in-situ solid-phase reactions and synergistic modification of multiple components during subsequent calcination. Thorough grinding ensures close contact of the raw materials at the microscopic scale.
[0032] Step 2: Calcine the calcined precursor obtained in Step 1 to obtain the Ce-Co complex.
[0033] This calcination step is a key step in achieving the in-situ coupling of multiple modification mechanisms in this application. Under high-temperature calcination conditions, cerium nitrate decomposes to generate CeO2, and the sulfur-containing Co3O4 precursor is converted to Co3O4. Furthermore, the sulfur element in the sulfur source is converted to S². - The form partially replaces oxygen in the CeO2 lattice, introducing lattice strain and impurity energy levels, narrowing the band gap of CeO2, and enhancing its visible light response. Simultaneously, multiphase mineral components in the red mud, such as SiO2, Fe2O3, and Al2O3, undergo in-situ solid-state reactions with the generated S-doped CeO2 and Co3O4, constructing a three-phase heterogeneous interface composed of red mud-derived phases, sulfur-doped CeO2 phases, and Co3O4 phases. In this interface, SiO2 and CeO2 can form Si-O-Ce covalent bonds, serving as bridging channels for charge transport and reducing interfacial charge transport resistance; Fe2O3 and Co3O4 form pn heterojunctions, promoting spatial separation of photogenerated carriers. Potassium chloride melts at this temperature, and its melt etching effect simultaneously induces oxygen overflow from the CeO2 lattice, forming abundant surface oxygen vacancy defects, and constructing interconnected mesopores and micropores in the product through a dissolution-reprecipitation mechanism. This step yields a porous powdered Ce-Co composite that integrates multiple modification effects.
[0034] Step 3: Add acrylic acid and glycerol to deionized water and stir to obtain the first mixed solution; weigh N'N-methylenebisacrylamide and add it to the first mixed solution and continue stirring to obtain the second mixed solution; add ammonium bicarbonate to the second mixed solution and continue stirring to obtain the third mixed solution; add the Ce-Co composite obtained in Step 2 to the third mixed solution and continue stirring to obtain the fourth mixed solution; add sodium bicarbonate to the fourth mixed solution, heat and purge with nitrogen gas, and after aging treatment, obtain CeO2-Co3O4 composite gel material.
[0035] This step aims to load and immobilize the aforementioned Ce-Co composite powder, which possesses a porous structure and a three-phase heterogeneous interface, within a gel framework. Acrylic acid serves as the polymerizing monomer, glycerol as a crosslinking aid or plasticizer, and N'N-methylenebisacrylamide as a crosslinking agent, collectively constituting the organic framework precursor of the gel. The addition of ammonium bicarbonate adjusts the pH of the system and participates in pore formation. Adding the Ce-Co composite powder to this solution and stirring allows for coordination complexation between the carboxyl groups on the acrylic acid molecular chains and the Ce and Co metal ions on the composite surface, achieving molecular-level uniform dispersion of the powder in the liquid precursor and effectively inhibiting nanoparticle aggregation. After adding sodium bicarbonate, heating and purging with nitrogen gas to provide an anaerobic environment initiate the free radical polymerization reaction of acrylic acid, forming a crosslinked network structure that uniformly encapsulates and immobilizes the Ce-Co composite within it. During heating, sodium bicarbonate partially decomposes to produce carbon dioxide gas. This gas, escaping from the gel, acts as a macroscopic pore-forming agent, creating macropores. These macropores, in conjunction with the mesopores and micropores formed by potassium chloride etching during the calcination step, ultimately construct a continuous hierarchical pore structure of macropores, mesopores, and micropores within the gel material. This structure is highly beneficial for mass transfer of reactants and exposure of active sites. The final curing treatment further refines and stabilizes the gel network structure. Through this step, a CeO2-Co3O4 composite gel material with strong visible light response, high carrier separation and transport efficiency, abundant active sites, and unobstructed mass transfer channels is obtained, fundamentally solving the problem of low charge separation efficiency in existing technologies.
[0036] The specific method for preparing the Co3O4 precursor containing a sulfur source is as follows: Step a: Add cobalt nitrate to deionized water and stir to obtain solution A; add thiourea, ammonium fluoride and urea to deionized water and stir to obtain solution B.
[0037] In this step, cobalt nitrate is used as the cobalt source, thiourea serves as both a sulfur source and a morphology modifier, and ammonium fluoride and urea are used as precipitants and pH adjusters.
[0038] Step b: Add solution B to solution A and stir until homogeneous. After heating and reacting, wash the mixture alternately with deionized water and anhydrous ethanol, and finally dry it to obtain cobalt powder.
[0039] During the heating reaction, cobalt ions in the solution undergo a homogeneous precipitation reaction under the combined action of thiourea, ammonium fluoride, and urea, generating a sulfur-containing cobalt-based precursor with a specific microstructure. Washing and drying steps are used to remove unreacted ions and impurities, yielding pure cobalt powder.
[0040] Step c: Add the cobalt powder obtained in step b to the acid solution and stir, heat under reflux and pass argon gas through, then wash until neutral to obtain a Co3O4 precursor containing a sulfur source.
[0041] The role of the acid is to etch and reshape the surface structure of the cobalt powder obtained in step b. Under the protection of heating reflux and inert atmosphere, it induces the cobalt powder to undergo a controllable in-situ phase transformation or surface modification, transforming it into a Co3O4 precursor suitable for the subsequent main process calcination step. Washing to neutrality is to remove residual acid and reaction byproducts.
[0042] By introducing the sulfur source into the Co3O4 precursor through the above independent pretreatment steps, it can be ensured that the sulfur doping and the construction of the three-phase heterogeneous interface can be carried out more efficiently and in a more controllable manner during subsequent co-calcination with cerium nitrate, red mud, etc.
[0043] In step one, by mass fraction, cerium nitrate can be 5.5 to 7.2 parts, Co3O4 precursor can be 0.8 to 1.4 parts, citric acid can be 0.45 to 0.75 parts, potassium chloride can be 10 to 15 parts, and red mud can be 2.5 to 3 parts. Selecting a proportion within the above range helps balance the reactivity of each component during calcination, ensuring sufficient construction of the three-phase heterogeneous interface and maximizing the pore-forming effect of molten salt etching, while avoiding raw material waste or side reactions. In step two, the calcination temperature can be 700 to 900°C, the time can be 3 to 4 hours, and the heating rate can be 8 to 12°C / min. This temperature range is higher than the melting point of potassium chloride, ensuring the molten etching process without causing the resulting mesoporous structure to collapse due to high-temperature sintering; a constant heating rate is beneficial for the crystallinity of the product and the uniformity of the pore structure. In step three, by mass fraction, acrylic acid can be 3 to 5 parts, glycerol can be 3 to 5 parts, N'N-methylenebisacrylamide can be 0.2 to 0.4 parts, sodium bicarbonate can be 2 to 4 parts, and ammonium bicarbonate can be 1 part. The appropriate ratio of crosslinking agent to monomer determines the crosslinking density and mechanical strength of the gel network, thus affecting its structural stability and the retention of internal mass transfer channels. The amount of sodium bicarbonate directly affects the number and size of macropores. In step three, the heating temperature can be 70 to 110°C, the heating time is 15 to 30 minutes, and the nitrogen flow rate is 40 to 60 mL / min; the curing temperature is 20 to 30°C, and the curing time is 10 to 14 hours. At these temperatures and times, the polymerization reaction can occur smoothly, and the decomposition and pore-forming rate of sodium bicarbonate matches the formation rate of the gel network, which is beneficial for forming a uniformly structured hierarchical porous material. Sufficient curing ensures the full relaxation of polymer chain segments and the final stability of the network.
[0044] This embodiment further optimizes the S doping effect, the construction quality of the three-phase heterogeneous interface, the connectivity of the hierarchical pore structure, and the dispersion uniformity of the active components by limiting the specific process parameters mentioned above, thereby making the final CeO2-Co3O4 composite gel material more stable and efficient in charge separation.
[0045] Example 1 A CeO2-Co3O4 composite gel material comprises the following materials in parts by weight: 3 parts acrylic acid, 5.5 parts cerium nitrate, 0.8 parts Co3O4 precursor containing sulfur source, 3 parts glycerol, 1 part ammonium bicarbonate, 2.5 parts red mud, 0.45 parts citric acid, 10 parts KCl and 0.2 parts N'N-methylenebisacrylamide; The preparation method of the Co3O4 precursor containing a sulfur source includes the following steps: a. Weigh 15 parts of cobalt nitrate and add them to 100 parts of deionized water. Stir at 1200 r / min for 1 h to obtain solution A. Weigh 2.2 parts of thiourea, 25 parts of ammonium fluoride and 3.5 parts of urea and add them to 100 parts of deionized water. Stir at 1200 r / min for 1 h to obtain solution B. b. Add the B solution obtained in step a to the A solution obtained in step a, stir at 800 r / min for 4 h, heat at 120℃ for 15 h, wash with deionized water and anhydrous ethanol alternately 5 times each, and dry at 80℃ for 24 h to obtain Co powder. c. Add the Co powder obtained in step b to 200 parts of acid solution, wherein the acid solution is a citric acid solution with a concentration of 0.25 mol / L, stir at 800 r / min for 12 h, heat and reflux at 90℃ for 12 h, and introduce Ar gas at a flow rate of 50 mL / min. Wash with deionized water until neutral to obtain a Co3O4 precursor containing a sulfur source.
[0046] This embodiment also provides a method for preparing a CeO2-Co3O4 composite gel material, comprising the following steps: Step 1: Weigh 5.5 parts of cerium nitrate, 0.8 parts of Co3O4 precursor containing sulfur source, 0.45 parts of citric acid, 10-15 parts of KCl and 2.5 parts of red mud (sieved using a 200-mesh screen), mix and grind them to obtain the calcination precursor; Step 2: Calcine the calcined precursor obtained in Step 1 at 700℃ for 3-4 hours at a heating rate of 10℃ / min to obtain the Ce-Co composite. Step 3: Weigh 3 parts acrylic acid and 3 parts glycerol and add them to 25 parts deionized water. Stir at 600 r / min for 30 min. Weigh 0.2 parts N'N-methylenebisacrylamide and add them to the mixture. Continue stirring at the same speed for 30 min. Weigh 1 part ammonium bicarbonate and add it to the mixture. Continue stirring at the same speed for 30 min. Add the Ce-Co composite obtained in Step 2 and continue stirring at the same speed for 30 min. Weigh 2 parts sodium bicarbonate and add it to the mixture. Heat at 70℃ for 15 min and purge with nitrogen gas at a flow rate of 50 mL / min. Cure at 25℃ for 12 h to obtain the CeO2-Co3O4 composite gel material.
[0047] Example 2 A CeO2-Co3O4 composite gel material comprises the following materials in parts by weight: 4 parts acrylic acid, 6.5 parts cerium nitrate, 1.1 parts Co3O4 precursor containing sulfur source, 4 parts glycerol, 1 part ammonium bicarbonate, 2.8 parts red mud, 0.55 parts citric acid, 13 parts KCl and 0.3 parts N'N-methylenebisacrylamide; The preparation method of the Co3O4 precursor containing a sulfur source includes the following steps: a. Weigh 18 parts of cobalt nitrate and add them to 100 parts of deionized water. Stir at 1200 r / min for 1 h to obtain solution A. Weigh 3.5 parts of thiourea, 35 parts of ammonium fluoride and 4.8 parts of urea and add them to 100 parts of deionized water. Stir at 1200 r / min for 1 h to obtain solution B. b. Add the B solution obtained in step a to the A solution obtained in step a, stir at 800 r / min for 4 h, heat at 135℃ for 18 h, wash with deionized water and anhydrous ethanol alternately 5 times each, and dry at 80℃ for 24 h to obtain Co powder. c. Add the Co powder obtained in step b to 200 parts of acid solution, wherein the acid solution is a citric acid solution with a concentration of 0.25 mol / L, stir at 800 r / min for 12 h, heat and reflux at 110℃ for 12 h, and introduce Ar gas at a flow rate of 50 mL / min. Wash with deionized water until neutral to obtain a Co3O4 precursor containing a sulfur source.
[0048] This embodiment also provides a method for preparing a CeO2-Co3O4 composite gel material, comprising the following steps: Step 1: Weigh 6.5 parts of cerium nitrate, 1.1 parts of Co3O4 precursor containing sulfur source, 0.55 parts of citric acid, 13 parts of KCl and 2.8 parts of red mud (sieved using a 200-mesh screen), mix and grind them to obtain the calcination precursor; Step 2: The calcined precursor obtained in Step 1 is calcined at 800℃ for 3.5h at a heating rate of 10℃ / min to obtain the Ce-Co composite. Step 3: Weigh 4 parts acrylic acid and 4 parts glycerol and add them to 25 parts deionized water. Stir at 600 r / min for 30 min. Weigh 0.3 parts N'N-methylenebisacrylamide and add them to the mixture. Continue stirring at the same speed for 30 min. Weigh 1 part ammonium bicarbonate and add it to the mixture. Continue stirring at the same speed for 30 min. Add the Ce-Co composite obtained in Step 2 and continue stirring at the same speed for 30 min. Weigh 3 parts sodium bicarbonate and add it to the mixture. Heat at 90℃ for 20 min and purge with nitrogen gas at a flow rate of 50 mL / min. Cure at 25℃ for 12 h to obtain the CeO2-Co3O4 composite gel material.
[0049] Example 3 A CeO2-Co3O4 composite gel material comprises the following materials in parts by weight: 5 parts acrylic acid, 7.2 parts cerium nitrate, 1.4 parts Co3O4 precursor containing sulfur source, 5 parts glycerol, 1 part ammonium bicarbonate, 3 parts red mud, 0.75 parts citric acid, 15 parts KCl and 0.4 parts N'N-methylenebisacrylamide; The preparation method of the Co3O4 precursor containing a sulfur source includes the following steps: a. Weigh 20 parts of cobalt nitrate and add them to 100 parts of deionized water. Stir at 1200 r / min for 1 h to obtain solution A. Weigh 4.5 parts of thiourea, 45 parts of ammonium fluoride and 6 parts of urea and add them to 100 parts of deionized water. Stir at 1200 r / min for 1 h to obtain solution B. b. Add the B solution obtained in step a to the A solution obtained in step a, stir at 800 r / min for 4 h, heat at 150℃ for 24 h, wash with deionized water and anhydrous ethanol alternately 5 times each, and dry at 80℃ for 24 h to obtain Co powder. c. Add the Co powder obtained in step b to 200 parts of acid solution, wherein the acid solution is a citric acid solution with a concentration of 0.25 mol / L, stir at 800 r / min for 12 h, heat and reflux at 120℃ for 12 h, and introduce Ar gas at a flow rate of 50 mL / min. Wash with deionized water until neutral to obtain a Co3O4 precursor containing a sulfur source.
[0050] This embodiment also provides a method for preparing a CeO2-Co3O4 composite gel material, comprising the following steps: Step 1: Weigh 7.2 parts of cerium nitrate, 1.4 parts of Co3O4 precursor containing sulfur source, 0.75 parts of citric acid, 15 parts of KCl and 3 parts of red mud (sieved using a 200-mesh screen), mix and grind them to obtain the calcination precursor; Step 2: Calcine the calcined precursor obtained in Step 1 at 900℃ for 3-4 hours at a heating rate of 10℃ / min to obtain the Ce-Co composite. Step 3: Weigh 5 parts acrylic acid and 5 parts glycerol and add them to 25 parts deionized water. Stir at 600 r / min for 30 min. Weigh 0.4 parts N'N-methylenebisacrylamide and add them to the mixture. Continue stirring at the same speed for 30 min. Weigh 1 part ammonium bicarbonate and add it to the mixture. Continue stirring at the same speed for 30 min. Add the Ce-Co composite obtained in Step 2 and continue stirring at the same speed for 30 min. Weigh 4 parts sodium bicarbonate and add it to the mixture. Heat at 110℃ for 30 min and purge with nitrogen gas at a flow rate of 50 mL / min. Cure at 25℃ for 12 h to obtain the CeO2-Co3O4 composite gel material.
[0051] The CeO2-Co3O4 composite gel material prepared by the above method has a three-phase heterogeneous interface consisting of a red mud-derived phase, a sulfur-doped CeO2 phase, and a Co3O4 phase.
[0052] To further verify the technical effect of this application, the photocatalytic nitrogen reduction synthesis performance of the material prepared in this embodiment was tested and compared with several comparative examples, wherein: The difference between Comparative Example 1 and Example 2 is that Ce-Co complex was not added; otherwise, they are the same as Example 2. The difference between Comparative Example 2 and Example 2 is that cerium nitrate was not added; otherwise, they are the same as Example 2. The difference between Comparative Example 3 and Example 2 is that the Co3O4 precursor was not added; otherwise, they are the same as Example 2. Comparative Example 4 uses a single CeO2, prepared as follows: Step 1: Weigh 6.5 parts of cerium nitrate and grind them to obtain the calcined precursor; Step 2: Calcine the calcination precursor obtained in Step 1 at 480℃ for 3.5h at a heating rate of 10℃ / min to obtain CeO2. Comparative Example 5 uses a single Co3O4, prepared as follows: Step 1: Weigh 1.1 parts of the Co3O4 precursor containing a sulfur source and grind it to obtain the calcined precursor; Step 2: The calcination precursor obtained in Step 1 is calcined at 480℃ for 3.5h at a heating rate of 10℃ / min to obtain Co3O4.
[0053] See test results Figure 2 Under the same testing conditions, the ammonia yield of the CeO2-Co3O4 composite gel material prepared in this embodiment was significantly higher than that of all comparative examples. Comparative examples 1 to 3 exhibited a sharp decline in performance due to the absence of key components for constructing heterojunctions or composite structures; the pure-phase materials of comparative examples 4 and 5 showed extremely low performance due to narrow light absorption range and severe carrier recombination. This demonstrates that the present invention effectively solves the core problem of low charge separation efficiency through the in-situ synergistic application of multiple modification strategies, including sulfur doping, three-phase heterostructure construction, hierarchical pore formation, and high dispersion of active components, thereby macroscopically manifesting as a significant improvement in photocatalytic nitrogen fixation performance.
[0054] Finally, it should be noted that the embodiments listed above are merely one or more specific manifestations of the technical solution of this invention. Their purpose is to clearly illustrate the concept, principle, and application of this invention through specific examples, and is by no means intended to limit the scope of protection of this invention to these specific embodiments. In fact, the true value of this invention lies in its proposed technical ideas and innovations, rather than its manifestations or implementation methods.
[0055] For those skilled in the art, after thoroughly reading and understanding the technical solution of this invention, they are fully capable of making various changes, modifications, or equivalent substitutions to the specific implementation of the invention based on their own professional knowledge and skills. These changes may include, but are not limited to: adjusting the range of technical parameters, optimizing the algorithm flow to improve efficiency, and replacing some technical components to achieve better compatibility or reduce costs. As long as these modified technical solutions substantially retain the technical features claimed by the original invention, that is, they can still achieve the core functions and effects of this invention, then these changes should be considered to fall within the scope of protection of the pending claims of this invention.
[0056] Furthermore, with the continuous progress and development of technology, new technical means and methods are constantly emerging, which provides ample space for further improvement and perfection of this invention. Therefore, the scope of protection of this invention should also include reasonable and foresightful improvements and extensions based on existing technology. As long as these improvements and extensions do not depart from the basic principles and core concepts of this invention, they should be considered equivalents of this invention and are equally protected by patent rights.
Claims
1. A method for preparing a CeO2-Co3O4 composite gel material, characterized in that, Includes the following steps: Step 1: Mix and grind cerium nitrate, citric acid, potassium chloride, red mud and Co3O4 precursor containing sulfur source to obtain calcination precursor; Step 2: Calcine the precursor to obtain the Ce-Co complex; Step 3: Add acrylic acid and glycerol to deionized water and stir to obtain the first mixed solution. Weigh N'N-methylenebisacrylamide and add it to the first mixed solution and continue stirring to obtain the second mixed solution. Add ammonium bicarbonate to the second mixed solution and continue stirring to obtain the third mixed solution. Add the Ce-Co composite to the third mixed solution and continue stirring to obtain the fourth mixed solution. Add sodium bicarbonate to the fourth mixed solution, heat and purge with nitrogen gas, and after aging treatment, obtain the CeO2-Co3O4 composite gel material.
2. The method for preparing a CeO2-Co3O4 composite gel material according to claim 1, characterized in that, The preparation method of the Co3O4 precursor containing a sulfur source specifically includes the following steps: Step a: Add cobalt nitrate to deionized water and stir to obtain solution A; add thiourea, ammonium fluoride and urea to deionized water and stir to obtain solution B; Step b: Add solution B to solution A and stir until homogeneous. After heating and reacting, wash the solution alternately with deionized water and anhydrous ethanol, and then dry to obtain cobalt powder. Step c: Add cobalt powder to acid solution and stir, heat under reflux and pass argon gas through, then wash until neutral to obtain Co3O4 precursor containing sulfur source.
3. The method for preparing a CeO2-Co3O4 composite gel material according to claim 2, characterized in that, In step a, by mass parts, cobalt nitrate is 15-20 parts, thiourea is 2.2-4.5 parts, ammonium fluoride is 25-45 parts, and urea is 3.5-6 parts.
4. The method for preparing a CeO2-Co3O4 composite gel material according to claim 2, characterized in that, In step b, the heating temperature is 120~150℃ and the heating time is 15~24h; the drying temperature is 75~85℃ and the drying time is 20~28h.
5. The method for preparing a CeO2-Co3O4 composite gel material according to claim 2, characterized in that, In step c, the acid solution is a citric acid solution with a concentration of 0.2~0.3 mol / L, the reflux temperature is 90~120℃, and the time is 10~14h; the argon flow rate is 40~60mL / min.
6. The method for preparing a CeO2-Co3O4 composite gel material according to claim 1, characterized in that, In step one, by mass fraction, cerium nitrate is 5.5-7.2 parts, Co3O4 precursor is 0.8-1.4 parts, citric acid is 0.45-0.75 parts, potassium chloride is 10-15 parts, and red mud is 2.5-3 parts.
7. The method for preparing a CeO2-Co3O4 composite gel material according to claim 1, characterized in that, In step two, the calcination temperature is 700~900℃, the time is 3~4h, and the heating rate is 8~12℃ / min.
8. The method for preparing a CeO2-Co3O4 composite gel material according to claim 1, characterized in that, In step three, by mass parts, acrylic acid is 3-5 parts, glycerol is 3-5 parts, N'N-methylenebisacrylamide is 0.2-0.4 parts, sodium bicarbonate is 2-4 parts, and ammonium bicarbonate is 1 part.
9. The method for preparing a CeO2-Co3O4 composite gel material according to claim 1, characterized in that, In step three, the heating temperature is 70~110℃, the heating time is 15~30min, and the nitrogen flow rate is 40~60mL / min; the aging temperature is 20~30℃, and the aging time is 10~14h.
10. A CeO2-Co3O4 composite gel material, characterized in that, The CeO2-Co3O4 composite gel material is prepared by any of the preparation methods of claims 1 to 9, wherein the CeO2-Co3O4 composite gel material forms a three-phase heterogeneous interface consisting of a red mud-derived phase, a sulfur-doped CeO2 phase, and a Co3O4 phase.