Iron-carbon co-modified graphite phase carbon nitride-based catalytic material, preparation method and application thereof

Abstract

This invention discloses an iron-carbon co-modified graphitic carbon nitride-based catalytic material, its preparation method, and its application. The invention involves dispersing melamine and acetamide in ethanol and stirring for 12 hours to obtain solution A; dispersing cyanuric acid and FeCl3·6H2O in ethanol and stirring for 12 hours to obtain solution B; mixing solutions A and B and stirring thoroughly; and then hydrothermally reacting the mixture at 180°C. The reaction product is washed until neutral, centrifuged, and dried to obtain a Fe / C-C3N4 precursor; the precursor is transferred to a tube furnace and calcined at 550°C for 2 hours to obtain the iron-carbon co-modified graphitic carbon nitride-based catalytic material. This catalytic material can be used for the photocatalytic degradation of antibiotic pollutants in water. This invention features a simple preparation process, low raw material costs, good environmental compatibility, and can efficiently and deeply purify antibiotic pollutants in water.

Description

Technical Field

[0001] This invention relates to the field of water pollution treatment technology, and in particular to an iron-carbon co-modified graphite phase carbon nitride-based (Fe / C-C3N4) catalytic material, its preparation method, and its application. Background Technology

[0002] Against the backdrop of increasingly severe global water pollution control, recalcitrant organic pollutants (ROS) have become a core challenge restricting the improvement of water quality safety due to their high stability, high biotoxicity, and significant environmental accumulation effects. Advanced oxidation processes (AOPs) generate highly reactive oxygen species (ROS) in situ, which can rapidly destroy the chemical structure of organic pollutants, providing an effective way to efficiently remove these pollutants. Among them, sustainable photocatalysis and multiphase Fenton-like processes are considered to have the greatest potential for industrial application due to their advantages such as green energy saving and mild reaction conditions. However, both technologies face key bottlenecks in practical applications: for photocatalysis, the photogenerated electron-hole pairs on the surface of semiconductor photocatalysts recombine easily, leading to slow charge separation and transfer kinetics, significantly weakening the photocatalytic oxidation efficiency; while in multiphase Fenton-like processes, Fe... 3+ To Fe 2+ The slow reduction reaction rate directly limits the activation efficiency of H2O2, ultimately leading to a severe deficiency in the generation of hydroxyl radicals (·OH), the core active species in both processes. This lack of ·OH not only makes it difficult to completely degrade organic pollutants, resulting in residual products with high biotoxicity, but also weakens the system's resistance to interference—due to the presence of coexisting ions commonly found in actual wastewater (such as Cl-). - HCO3 - Waterborne matrices such as dissolved organic matter (DOM) can further inhibit degradation efficiency through competitive adsorption and quenching of active species. Therefore, how to overcome the inherent limitations of single photocatalysis or Fenton processes and achieve deep oxidation of recalcitrant organic micropollutants into low-toxicity or non-toxic products has become a core challenge that urgently needs to be addressed in the field of environmental catalysis.

[0003] To address the aforementioned technical bottlenecks, photocatalysis is coupled with a multiphase Fenton-like process to construct a multiphase photo-Fenton-like catalytic oxidation system that combines high stability and high efficiency, opening a new pathway for the deep purification of recalcitrant organic micropollutants in wastewater. In this composite system, photogenerated electrons from the photocatalytic process can be rapidly transferred to the Fenton-like reaction system, significantly accelerating the reduction kinetics of ferric ions to ferrous ions, thereby improving the catalytic activation efficiency of H₂O₂ and ultimately achieving the large-scale generation of highly reactive hydroxyl radicals (·OH). Currently, this direction has become a research hotspot in the field of environmental catalysis.

[0004] In recent years, numerous studies have revealed the potential risks of antibiotic pollutants in water bodies to the ecological environment and human health, prompting the rapid development of various water treatment technologies. Among these, catalytic oxidation technologies based on strategies such as semiconductor photocatalysis, heterogeneous Fenton / Fenton-like processes, and adsorption-catalysis synergy have become research hotspots. For example, titanium dioxide (TiO2)-based composite materials, with their excellent chemical stability and photocatalytic activity, have been widely used in the degradation of antibiotics such as tetracycline and levofloxacin. Bismuth-based photocatalysts (such as Bi2WO6 and BiOBr) achieve visible light response by modulating the band structure, showing certain advantages in the removal of low-concentration antibiotics. In addition, transition metal oxides derived from metal-organic frameworks (MOFs) (such as Co3O4) have attracted much attention in the field of Fenton-like catalytic degradation of antibiotics due to their abundant active sites. However, these existing technologies still have significant shortcomings: TiO2-based materials have a wide band gap (~3.2 eV), can only respond to ultraviolet light, and have a fast photogenerated charge recombination rate, resulting in limited degradation efficiency in actual water bodies; bismuth-based catalysts have catalytic active sites that are prone to aggregation, have poor long-term cycling stability, and are susceptible to coexisting ions in complex water conditions (such as Cl-). - HCO3 - While MOF-derived catalysts exhibit high activity, their preparation process is complex and costly, and the leaching of transition metals can easily cause secondary pollution to water bodies. Furthermore, single catalytic systems (such as pure photocatalysis or pure Fenton-like catalysts) generally suffer from insufficient deep oxidation capacity: antibiotic molecules are only partially degraded into intermediate products, making complete mineralization difficult, and residual intermediates may produce higher ecotoxicity. Graphitic carbon nitride (g-C3N4), as a typical polymer semiconductor, has become our core carrier choice for constructing an efficient antibiotic degradation system, with particularly prominent advantages: Firstly, g-C3N4 has a suitable band structure (band gap ~2.7 eV), effectively responding to visible light and possessing strong light-harvesting capabilities, meeting the energy requirements of practical water treatment; secondly, its molecular structure is rich in sp... 2 The hybridized nitrogen atoms form a unique "six-membered cavity" structure, which can anchor transition metal active sites through coordination, while also participating in the reaction as non-metallic catalytic sites. Thirdly, it exhibits excellent chemical stability, its raw materials (such as melamine and urea) are inexpensive and readily available, and it carries no risk of metal leaching, demonstrating good environmental compatibility. However, pure g-C3N4 also has inherent drawbacks: severe interlayer stacking leads to a small specific surface area and insufficient exposure of active sites; the photogenerated electron-hole recombination rate is fast, resulting in low charge separation efficiency; and poor surface hydrophilicity leads to weak interaction with antibiotic molecules in water, limiting the catalytic reaction kinetics.

[0005] In summary, the layer stacking problem of pure g-C3N4 is the bottleneck of its catalytic performance, which directly leads to insufficient exposure of active sites, resulting in a series of derivative problems such as slow degradation rate, low removal efficiency of low-concentration pollutants, and poor long-term stability, which seriously limits its application in the purification of antibiotics in actual water bodies. Summary of the Invention

[0006] To overcome the shortcomings of existing technologies, the purpose of this invention is to provide an iron-carbon co-modified graphitic carbon nitride-based (Fe / C-C3N4) catalytic material, its preparation method, and its application.

[0007] The technical solution provided by this invention is as follows: A method for preparing an iron-carbon co-modified graphitic carbon nitride-based catalytic material, the method comprising the following steps: (1) Disperse melamine and acetamide in ethanol and stir for 12 hours to obtain solution A; disperse cyanuric acid and FeCl3·6H2O in ethanol and stir for 12 hours to obtain solution B; (2) Mix solutions A and B and stir until homogeneous. Perform hydrothermal reaction at 180°C. Wash the reaction product until neutral and centrifuge and dry to obtain Fe / C-C3N4 precursor. (3) The precursor is transferred to a tube furnace and calcined at 550°C for 2 hours to obtain iron-carbon co-modified graphite phase carbon nitride-based catalyst.

[0008] Preferably, in step (1), the mass-to-volume ratio of melamine, acetamide, and ethanol in solution A is 2.8~3.15 g: 0.035 g: 22~38 mL;

[0009] Preferably, in step (1), the mass-to-volume ratio of cyanuric acid, cyanuric acid and FeCl3·6H2O in solution B is 3g:0.01g:24~36mL.

[0010] Preferably, in step (1), the mass-to-volume ratio of melamine, acetamide, and ethanol in solution A is 3 g: 0.035 g: 30 mL; and the mass-to-volume ratio of cyanuric acid, FeCl3·6H2O, and ethanol in solution B is 3 g: 0.01 g: 30 mL.

[0011] Preferably, in step (2), the volume ratio of solution A to solution B is 1:1, and the hydrothermal reaction time is 12 h.

[0012] Preferably, in step (2), the washing involves washing the reaction product three times each with deionized water and anhydrous ethanol until it becomes neutral.

[0013] This invention further discloses the iron-carbon co-modified graphitic carbon nitride-based catalytic material prepared by the above method.

[0014] This invention further discloses the application of the above-mentioned iron-carbon co-modified graphite phase carbon nitride-based catalytic material in the photocatalytic degradation of antibiotic pollutants in water.

[0015] Preferably, the antibiotic contaminants include tetracycline hydrochloride and levofloxacin.

[0016] To address the aforementioned shortcomings of pure g-C3N4 and leverage the advantages of photo-Fenton-like synergistic catalysis, this invention provides an iron-carbon co-modified graphitic carbon nitride-based (Fe / C-C3N4) catalytic material, its preparation method, and its applications. Fe, as the core active site for heterogeneous Fenton-like reactions, can synergistically enhance the photocatalytic performance of g-C3N4. Meanwhile, C doping / modification can optimize the intrinsic properties of g-C3N4 at the structural and electronic levels. The synergistic effect of these two factors achieves a comprehensive improvement in catalytic performance. The specific regulatory mechanisms and advantages are as follows: Firstly, from a structural regulation perspective, the introduction of carbon-based species (amorphous carbon, carbon nanotubes, graphene quantum dots, etc.) can intercalate into the interlayer of g-C3N4, breaking the interlayer hydrogen bonds and π-π stacking, achieving layer exfoliation and pore structure regulation of g-C3N4, significantly increasing the material's specific surface area and pore volume, and fully exposing the non-metallic catalytic sites of g-C3N4 itself. Simultaneously, Fe-based active species (Fe... 2+ / Fe 3+ Iron oxides and iron-based nanoparticles can be anchored to the carbon and nitrogen active sites of g-C3N4 through Fe-N and Fe-C coordination bonds, effectively inhibiting the aggregation of Fe-based species and improving the dispersibility and accessibility of active sites. Secondly, from the perspective of electronic structure optimization and photo-Fenton-like synergy, the electronegativity of C (2.55) and the N atom (3.04) and sp in g-C3N4 are related. 2 The electronegativity difference of hybrid C atoms allows for the formation of local electron density differences within the g-C3N4 lattice after doping, creating an internal electric field. Simultaneously, the d orbitals of Fe can couple with the π-conjugated orbitals of g-C3N4, forming a Fe-C3N4 heterojunction. These two factors synergistically accelerate the separation and directional transfer of photogenerated electron-hole pairs in g-C3N4, significantly suppressing charge recombination. More importantly, the photogenerated electrons produced by g-C3N4 photocatalysis can rapidly displace Fe in the system. 3+ Reduced to Fe 2+ To realize Fe in a Fenton-like system 2+ / Fe 3+ The efficient valence state cycle continuously catalyzes the decomposition of H2O2 to generate highly reactive oxidizing species such as ·OH, thus completely resolving the Fe content issue in pure Fenton-like systems. 2+The problems of rapid consumption and low oxidant utilization are addressed by achieving efficient coupling of photocatalysis and Fenton-like reactions. Thirdly, from the perspective of surface chemical properties and catalytic reaction kinetics regulation, Fe and C co-modification can reconstruct the surface properties of g-C3N4. The introduced functional groups such as CO, C=O, and Fe-OH can significantly improve the surface hydrophilicity of the material, enhance the adsorption and mass transfer of polar antibiotic molecules in water, and increase the probability of contact between pollutants and active sites. Simultaneously, Fe-C synergistically regulate the catalytic reaction pathway, in addition to the ·O2 generated by photocatalysis... - h + In addition to the ·OH produced by Fenton-like compounds, it can also promote 1 The synergistic generation of multiple reactive oxygen species, including O2, enables highly efficient attack and bond breaking of antibiotic molecules with different structures, enhancing the deep mineralization of antibiotics and avoiding the residue of intermediate products. Fourth, from a stability perspective, Fe-based species are tightly bound to g-C3N4 through coordination bonds, significantly reducing the risk of Fe leaching in complex water conditions and avoiding secondary pollution; at the same time, the doping of carbon-based species can enhance the structural stability of the g-C3N4 lattice, improving the material's resistance to interference and long-term cyclic stability in complex water conditions (containing high concentrations of coexisting ions and acid-base fluctuations).

[0017] This invention breaks the interlayer stacking at its source through precise structural regulation, achieving full exposure and stable retention of active sites. At the same time, it combines the characteristics of photo-Fenton-like synergistic catalysis to further optimize the electronic structure and surface reaction characteristics of g-C3N4, thereby improving its catalytic performance from multiple dimensions.

[0018] This invention addresses the shortcomings of existing technologies by designing a Fe / C co-doping strategy. Through the synergistic regulation of "structure-electronic-surface properties," it overcomes the following technical problems one by one: (1) Addressing structural stacking and insufficient active sites: The interlayer embedding of carbon-based species (amorphous carbon, carbon nanotubes) can directly break the interlayer hydrogen bonds and π-π stacking forces of g-C3N4, forcibly peeling off the layers to form a porous ultrathin nanostructure; at the same time, Fe-based active species are anchored on the g-C3N4 framework through Fe-N and Fe-C coordination bonds, forming a dual effect of "physical support + chemical anchoring", inhibiting the re-aggregation of layers and the aggregation of Fe-based species, significantly increasing the specific surface area and pore volume, fully exposing the non-metallic catalytic sites and Fe-based Fenton-like active sites in the interlayer and on the surface, and completely solving the core structural problems of insufficient active site supply and poor accessibility of g-C3N4. Addressing the fast photogenerated charge recombination and low charge separation efficiency: The electronegativity of C atoms (2.55) is lower than that of N atoms (3.04), sp 2The hybrid C atoms have different properties. After Fe and N co-modification, a local electron density gradient is formed in the g-C3N4 lattice, which constructs an internal electric field. At the same time, the d orbitals of Fe and the π conjugated orbitals of g-C3N4 are coupled to form Fe-C3N4 heterojunction. The two work together to accelerate the separation and directional transfer of photogenerated electron-hole pairs and significantly suppress charge recombination. Furthermore, by widening the charge delocalization range, the photon yield is improved, providing a sufficient electronic basis for the subsequent generation of active species.

[0019] (2) To address the issues of poor surface hydrophilicity and low interphase mass transfer efficiency of pollutants, Fe and C co-modification can reconstruct the surface chemical properties of g-C3N4, introduce polar functional groups such as CO, C=O, and Fe-OH, significantly improve the surface hydrophilicity of the material and its adsorption capacity for polar antibiotic molecules, enhance the contact rate between pollutants and active sites, and solve the problem of limited reaction kinetics.

[0020] (3) For traditional Fenton Fe 2+ / Fe 3+ The slow cycle and low oxidant utilization problems can be addressed by using photogenerated electrons generated by g-C3N4 photocatalysis to rapidly convert Fe... 3+ Reduced to Fe 2+ This constructs an efficient valence cycle, continuously catalyzing the decomposition of H2O2 to generate ·OH, significantly improving the utilization rate of the oxidant, and breaking the Fe-like system in pure Fenton systems. 2+ Bottlenecks in consumption. Addressing the issues of poor stability and metal leaching risk, Fe-based species are tightly bound to g-C3N4 through Fe-N / Fe-C coordination bonds, significantly reducing the risk of Fe leaching in complex water conditions and preventing secondary pollution. Simultaneously, the doping of carbon-based species enhances the structural stability of the g-C3N4 lattice, improving the material's resistance to interference and long-term cyclic stability in complex water conditions containing coexisting ions and fluctuating acidity and alkali levels, thus meeting the needs of practical water treatment.

[0021] In summary, Fe and C co-modification achieves highly efficient coupling of photocatalysis and Fenton-like reactions through synergistic regulation of the structure, electronic structure, and surface properties of g-C3N4. This not only overcomes the inherent defects of pure g-C3N4, such as small specific surface area, low charge separation efficiency, and poor hydrophilicity, but also solves the problems of active site aggregation and Fe in traditional heterogeneous Fenton-like systems. 2+ / Fe 3+ To address the issues of low cycle efficiency and low oxidant utilization, a Fe / C-C3N4 photo-Fenton-like catalytic system was finally constructed, which combines high visible light photocatalytic activity, high efficiency Fenton-like performance, and strong pollutant mineralization ability. This system has a simple preparation process, low raw material cost, and good environmental compatibility, providing a feasible technical solution and theoretical support for the efficient and in-depth purification of antibiotic pollutants in water.

[0022] The beneficial effects of this invention after adopting the above technical solution are as follows: (1) Through the dual effects of carbon-based species intercalation and Fe-based species coordination anchoring, not only are the interlayer hydrogen bonds and π-π stacking of g-C3N4 broken to form a porous ultrathin nanostructure, but also the secondary aggregation of the lamellar structure and the aggregation of active sites are inhibited from a thermodynamic perspective, thereby significantly improving the specific surface area and pore volume, and increasing the exposure rate of active sites by more than 60%, thus solving the core problems of insufficient supply of active sites and poor accessibility. The structural stability is far superior to traditional methods such as simple ultrasonic exfoliation and solvent intercalation.

[0023] (2) The difference in electronegativity of C atoms and the coupling of Fe-d orbitals with g-C3N4-π orbitals construct a dual charge separation channel with an internal electric field and a heterojunction, which significantly suppresses photogenerated electron-hole recombination; secondly, the photogenerated electron-mediated Fe 2+ / Fe 3+ Highly efficient valence state cycle, completely solving the problem of traditional Fenton-like Fe 2+ Addressing the pain points of rapid consumption and low oxidant utilization, the activation efficiency of H2O2 is increased by more than 40%, achieving a synergistic effect of "1+1>2" between photocatalysis and Fenton-like processes.

[0024] (3) The polar functional groups such as CO, C=O, and Fe-OH introduced by Fe and C co-modification significantly improve the hydrophilicity and antibiotic adsorption capacity of the material, thereby greatly increasing the probability of contact between pollutants and active sites. At the same time, the present invention uses inexpensive and readily available melamine (g-C3N4 raw material) and iron salt (Fe source) as raw materials, and the preparation process is simple, with a cost of only 1 / 3 to 1 / 2 of that of MOFs-derived catalysts. At the same time, it retains the visible light response characteristics of g-C3N4, which meets the energy requirements of actual water treatment and has significant prospects for industrial application.

[0025] In summary, this invention achieves a comprehensive leap in catalytic performance, stability, and practicality through a precise Fe and C co-modification strategy, completely solving the core pain points of existing carbon nitride-based and traditional catalytic technologies. It is a water antibiotic purification technology solution that combines theoretical innovation with engineering application value. Attached Figure Description

[0026] Figure 1 These are high-resolution scanning electron microscope (SEM) images; in which (a) graphitic carbon nitride (C3N4), (b) carbon-rich graphitic carbon nitride (C-C3N4), (c) graphitic carbon nitride loaded with Fe species (Fe / C3N4), and (d) Fe / C-C3N4. Figure 2 These are the degradation curves of tetracycline hydrochloride (TC) by Fe / C-C3N4 in different systems; among them, (a) is a Fenton system and (b) is a photo-Fenton system. Detailed Implementation

[0027] The technical solution of the present invention will be further described in detail below with reference to specific embodiments, but this does not constitute any limitation on the present invention.

[0028] Example 1 (1) Disperse 3 g of melamine and 0.035 g of acetamide in 30 mL of ethanol and stir for 12 hours to obtain solution A; disperse 3 g of cyanuric acid and 0.01 g of FeCl3·6H2O in 36 mL of ethanol and stir for 12 hours to obtain solution B; (2) Mix solution A and solution B in a volume ratio of 1:1 and stir until homogeneous. Then, perform a hydrothermal reaction at 180°C for 12 h. Wash the reaction product with deionized water and anhydrous ethanol three times each until neutral. After centrifugation and drying, obtain the Fe / C-C3N4 precursor. (3) The precursor was transferred to a tube furnace and calcined at 550°C for 2 hours to obtain iron-carbon co-modified graphite phase carbon nitride-based catalyst (Fe / C-C3N4).

[0029] Example 2 (1) Disperse 2.8 g of melamine and 0.035 g of acetamide in 38 mL of ethanol and stir for 12 hours to obtain solution A; disperse 3 g of cyanuric acid and 0.01 g of FeCl3·6H2O in 36 mL of ethanol and stir for 12 hours to obtain solution B; (2) Mix solution A and solution B in a volume ratio of 1:1 and stir until homogeneous. Then, perform a hydrothermal reaction at 180°C for 12 h. Wash the reaction product with deionized water and anhydrous ethanol three times each until neutral. After centrifugation and drying, obtain the Fe / C-C3N4 precursor. (3) The precursor was transferred to a tube furnace and calcined at 550°C for 2 hours to obtain iron-carbon co-modified graphite phase carbon nitride-based catalyst (Fe / C-C3N4).

[0030] Example 3 (1) Disperse 3.15 g of melamine and 0.035 g of acetamide in 22 mL of ethanol and stir for 12 hours to obtain solution A; disperse 3 g of cyanuric acid and 0.01 g of FeCl3·6H2O in 24 mL of ethanol and stir for 12 hours to obtain solution B; (2) Mix solution A and solution B in a volume ratio of 1:1 and stir until homogeneous. Then, perform a hydrothermal reaction at 180°C for 12 h. Wash the reaction product with deionized water and anhydrous ethanol three times each until neutral. After centrifugation and drying, obtain the Fe / C-C3N4 precursor. (3) The precursor was transferred to a tube furnace and calcined at 550°C for 2 hours to obtain iron-carbon co-modified graphite phase carbon nitride-based catalyst (Fe / C-C3N4).

[0031] Comparative Example 1 (1) Preparation of precursor solution: Weigh 3 g of melamine, disperse it in 30 mL of anhydrous ethanol, and stir magnetically for 12 h to obtain a uniformly dispersed precursor solution (referred to as blank solution A). (2) Preparation of the precursor solution: Weigh 3 g of cyanuric acid, disperse it in 30 mL of anhydrous ethanol, and stir magnetically for 12 h to obtain a uniformly dispersed solution (referred to as blank solution B). (3) Mixing and hydrothermal pretreatment: Mix blank A solution and blank B solution thoroughly and stir magnetically for 30 min until the system is homogeneous. Then transfer the mixture to a polytetrafluoroethylene-lined high-pressure reactor and perform a hydrothermal reaction at 180°C for 12 h. (4) Post-processing: After the hydrothermal reaction is completed, the reactor is allowed to cool naturally to room temperature. The product is then removed and repeatedly washed with deionized water and anhydrous ethanol until the filtrate is neutral (to remove unreacted precursors and impurities). Subsequently, it is vacuum dried at 60°C for 12 hours. (5) Calcination and molding: The dried precursor powder is transferred to a tube furnace and heated to 550°C at a heating rate of 2.5°C / min. It is then calcined at this temperature for 2 h (the calcination atmosphere is air or an inert atmosphere, preferably air). After natural cooling, pure graphitic carbon nitride is obtained and labeled as C3N4.

[0032] Comparative Example 2 (1) Preparation of carbon source-melamine precursor solution: Weigh 3 g of melamine and 35 mg of acetamide (carbon doping source), disperse them together in 30 mL of anhydrous ethanol, and stir magnetically for 12 h to obtain a uniformly dispersed solution A (containing carbon source precursor). (2) Preparation of cyanuric acid matching solution: Weigh 3 g of cyanuric acid, disperse it in 30 mL of anhydrous ethanol, and stir magnetically for 12 h to obtain a uniformly dispersed solution B (without iron source). (3) Mixing and hydrothermal pretreatment: Mix solution A and solution B, stir magnetically for 30 min until the system is homogeneous, transfer to a polytetrafluoroethylene-lined high-pressure reactor, and hydrothermally react at 180℃ for 12 h. (4) Post-treatment: After the reaction is completed, cool to room temperature, wash the product with deionized water and ethanol pentahydrate until the filtrate is neutral, and dry under vacuum at 60°C for 12 h; (5) Calcination and molding: The dry powder is placed in a tube furnace and heated to 550°C at 2.5°C / min. It is then calcined at a constant temperature for 2 hours and naturally cooled to obtain carbon-rich graphitic carbon nitride, which is labeled as C-C3N4 (C-CN).

[0033] Comparative Example 3 (1) Preparation of melamine precursor solution: Weigh 3 g of melamine, disperse it in 30 mL of anhydrous ethanol, and stir magnetically for 12 h to obtain a uniformly dispersed solution A (without carbon source). (2) Preparation of cyanuric acid-iron source composite solution: Weigh 3 g of cyanuric acid and 10 mg of ferric chloride hexahydrate (FeCl3・6H2O, Fe species precursor), disperse them together in 30 mL of anhydrous ethanol, and stir magnetically for 12 h to obtain a uniformly dispersed solution (containing iron source). (3) Mixing and hydrothermal pretreatment: Mix solution A and solution B, stir magnetically for 30 min until the system is homogeneous, transfer to a polytetrafluoroethylene-lined high-pressure reactor, and hydrothermally react at 180℃ for 12 h. (4) Post-treatment: After the reaction is completed, cool to room temperature, wash the product with deionized water until the filtrate is neutral (to remove free Cl⁻ and uncomplexed Fe ions), and dry under vacuum at 60℃ for 12h; (5) Calcination and shaping: The dry powder is placed in a tube furnace and heated to 550°C at 2.5°C / min. It is then calcined at a constant temperature for 2 h and naturally cooled to obtain Fe species-supported graphite phase carbon nitride, labeled as Fe / C3N4 (Fe-CN).

[0034] Effect Example The following experiments were conducted using the graphitic carbon nitride-based catalytic material (Fe / C-C3N4) prepared in Example 1, the graphitic carbon nitride (C3N4), carbon-rich graphitic carbon nitride (C-C3N4), and graphitic carbon nitride supported on Fe species (Fe / C3N4) prepared in the comparative examples.

[0035] 1. Observation of morphological features The morphological characteristics of Fe / C-C3N4 were observed using scanning electron microscopy (SEM), and reference samples such as graphitic carbon nitride (C3N4), carbon-rich graphitic carbon nitride (C-C3N4), and graphitic carbon nitride supported on Fe species (Fe / C3N4) were simultaneously tested. Figure 1 As shown in figure a, C3N4 exhibits a typical dense, blocky aggregated structure. This stems from the strong NH…N / C hydrogen bonds and π-π stacking between the triazine / heptaazine ring backbones formed by the thermal polymerization of melamine and acetamide. After introducing carbon-based species as a carbon source, the interlayer stacking of C3N4 is significantly disrupted, resulting in a loose, ultrathin nanosheet structure. Figure 1 (b) Carbon-based species intercalate into the C3N4 interlayer, disrupting interlayer hydrogen bonds and causing the thick sheets to peel away into thinner, more dispersed two-dimensional nanosheets, while simultaneously introducing numerous mesoporous and macroporous structures. This structure not only significantly increases the specific surface area but also inhibits secondary aggregation of the sheets through the supporting effect of the carbon-based structure, providing ample active sites for subsequent anchoring of Fe species. Figure 1 c. After iron salt doping, the lamellar morphology of Fe-C3N4 is similar to that of C-C3N4, but fine granular protrusions appear on the surface of the lamellars. After Fe / C co-modification, the material exhibits a highly dispersed porous nanosheet network structure, representing the optimal morphology of this system. Figure 1 d) Carbon-based intercalation completely exfoliates the C3N4 sheets, forming a two-dimensional structure only a few nanometers thick; simultaneously, Fe-based species are anchored to the carbon-modified sheet surface through Fe-N and Fe-C dual coordination bonds, without significant aggregation. This structure not only maximizes the exposure of non-metallic catalytic sites and Fe-based Fenton-like active sites of C3N4, but also accelerates the mass transfer of pollutants and the diffusion of reactive oxygen species through a porous network, providing a solid structural foundation for efficient photo-Fenton-like catalysis.

[0036] 2. Catalytic oxidation performance The heterogeneous photo-Fenton-like catalytic oxidation performance of Fe / C-C3N4 was evaluated by the degradation of tetracycline hydrochloride (TC). Experimental conditions: catalyst dosage 50 mg; initial TC concentration C0 = 10 mg·L⁻¹. -1 The reaction volume was 50 mL; the hydrogen peroxide concentration C(H2O2) = 50 mmol·L. -1 Wavelength λ > 400 nm. After 60 minutes of reaction, the removal efficiencies of TC were: 89% for the Fe / C-C3N4 type Fenton system and 100% for the Fe / C-C3N4 type photo-Fenton system. Figure 2 (a, 2b) These results indicate that the highly efficient activation energy of Fe / C-C3N4 for H2O2 under visible light irradiation significantly promotes the catalytic oxidation of TC. Exposing the non-metallic catalytic sites of C3N4 and the Fe-based Fenton-like active sites accelerates pollutant degradation, demonstrating that the precise Fe and C co-modification strategy achieves a comprehensive leap in catalytic performance, stability, and practicality.

[0037] The above embodiments are preferred embodiments of the present invention, but the embodiments of the present invention are not limited to the above embodiments. Any changes, modifications, substitutions, combinations, or simplifications made without departing from the spirit and principle of the present invention shall be considered equivalent substitutions and shall be included within the protection scope of the present invention.

Claims

1. A method for preparing an iron-carbon co-modified graphitic carbon nitride-based catalytic material, characterized in that, The method includes the following steps: (1) Disperse melamine and acetamide in ethanol and stir for 12 hours to obtain solution A; disperse cyanuric acid and FeCl3·6H2O in ethanol and stir for 12 hours to obtain solution B; (2) Mix solutions A and B and stir until homogeneous. Perform hydrothermal reaction at 180°C. Wash the reaction product until neutral and centrifuge and dry to obtain Fe / C-C3N4 precursor. (3) The precursor is transferred to a tube furnace and calcined at 550°C for 2 hours to obtain iron-carbon co-modified graphite phase carbon nitride-based catalyst.

2. The method as described in claim 1, characterized in that, In step (1), the mass-to-volume ratio of melamine, acetamide, and ethanol in solution A is 2.8~3.15 g: 0.035 g: 22~38 mL; In step (1), the mass-to-volume ratio of cyanuric acid, cyanuric acid and FeCl3·6H2O in solution B is 3 g: 0.01 g: 24~36 mL.

3. The method as described in claim 1, characterized in that, In step (1), the mass-volume ratio of melamine, acetamide and ethanol in solution A is 3 g: 0.035 g: 30 mL; the mass-volume ratio of cyanuric acid, FeCl3·6H2O and ethanol in solution B is 3 g: 0.01 g: 30 mL.

4. The method as described in claim 1, characterized in that, In step (2), the volume ratio of solution A to solution B is 1:1, and the hydrothermal reaction time is 12 h.

5. The method as described in claim 1, characterized in that, In step (2), the washing involves washing the reaction product three times each with deionized water and anhydrous ethanol until it becomes neutral.

6. The iron-carbon co-modified graphitic carbon nitride-based catalytic material prepared by the method described in claims 1 to 5.

7. The application of the iron-carbon co-modified graphite phase carbon nitride-based catalytic material according to claim 6 in the photocatalytic degradation of antibiotic pollutants in water.

8. The application as described in claim 7, characterized in that, The antibiotic contaminants include tetracycline hydrochloride and levofloxacin.

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