Preparation methods and applications of Ni3C / Bi5O7I composite materials

Abstract

This invention provides a method for preparing Ni3C / Bi5O7I composite material and its application, relating to the field of photocatalysis technology. The preparation method includes: Step 1: Adding KI to a suspension containing Bi(NO3)3·5H2O and NaOH, stirring, and then carrying out a hydrothermal reaction. The resulting product is cooled to room temperature, centrifuged, washed, and dried to obtain Bi5O7I; Step 2: Adding nickel acetate to an oleylamine aqueous solution under a nitrogen atmosphere, carrying out a hydrothermal reaction, cooling to room temperature, and the resulting precipitate is centrifuged, washed, and dried to obtain Ni3C; Step 3: Adding Bi(NO3)3·5H2O solution dropwise to a suspension containing Bi5O7I and Ni3C under vigorous stirring, and then carrying out a hydrothermal reaction. The resulting precipitate is centrifuged, washed, and vacuum dried to obtain Ni3C / Bi5O7I. This invention improves the photocatalytic activity of Bi5O7I by introducing Ni3C into it, and gives the resulting photocatalytic material the ability to efficiently and stably degrade phenol in water, which has potential application value in the field of phenol-containing wastewater purification.

Description

Technical Field

[0001] This invention relates to the field of photocatalysis technology, and in particular to the preparation method and application of Ni3C / Bi5O7I composite materials. Background Technology

[0002] Phenol is a common volatile organic compound and an important raw material for the production of resins, bactericides, preservatives, and pharmaceuticals (such as aspirin). Phenol is a major pollutant in industrial wastewater from oil refineries, petrochemical plants, coking plants, and phenolic resin plants. It may also be found in some agricultural products and animal excrement. However, phenol is a highly toxic organic pollutant, and phenol-containing wastewater, due to its toxicity and bioaccumulation, causes serious damage to the aquatic environment and poses a threat to human and biological health when discharged into waterways. Furthermore, international environmental organizations have set a phenol emission concentration limit of micrograms per liter. Therefore, phenol treatment is a challenging and significant engineering project. In recent decades, advanced oxidation processes (AOPs) have proven attractive for wastewater treatment. Currently, AOPs have been successfully applied to degrade persistent organic pollutants, converting toxic organic pollutants into easily degradable low-molecular-weight metabolites. Among advanced oxidation processes (AOPs), photocatalytic oxidation is a low-cost, green, and efficient method for phenol removal, although existing photocatalytic materials have relatively low degradation efficiency.

[0003] Bi5O7I is a newly discovered visible-light-driven photocatalyst with an optical band gap of approximately 2.8 eV. Its unique layered crystal structure results in an internal electrostatic field perpendicular to each layer, thereby promoting the separation of photogenerated carriers. Therefore, Bi5O7I photocatalysts exhibit good photoactivity in the degradation of methyl orange (MO) in water and acetaldehyde (CH3CHO) in air. However, its insufficient light absorption and low carrier transport efficiency limit its photocatalytic activity.

[0004] Therefore, in the field of photocatalysis technology, how to improve the photocatalytic activity of Bi5O7I and efficiently degrade phenol has become an urgent technical problem to be solved. Summary of the Invention

[0005] To address the above problems, in a first aspect, the present invention provides a method for preparing Ni3C / Bi5O7I composite materials, the method comprising:

[0006] Step 1: Add KI to a suspension containing Bi(NO3)3·5H2O and NaOH and stir, then carry out a hydrothermal reaction. The resulting product is cooled to room temperature, centrifuged, washed and dried to obtain Bi5O7I.

[0007] Step 2: Under a nitrogen atmosphere, nickel acetate was added to an aqueous solution of oleylamine and subjected to a hydrothermal reaction. After cooling to room temperature, the resulting precipitate was centrifuged, washed, and dried to obtain Ni3C.

[0008] Step 3: Bi(NO3)3·5H2O solution is added dropwise to a suspension containing Bi5O7I and Ni3C under vigorous stirring, and then a hydrothermal reaction is carried out. The resulting precipitate is centrifuged, washed, and vacuum dried to obtain Ni3C / Bi5O7I; wherein Ni3C accounts for 1% to 15% of the mass of Ni3C / Bi5O7I.

[0009] Preferably, in step 1, the suspension containing Bi(NO3)3·5H2O and NaOH is obtained by dissolving Bi(NO3)3·5H2O and NaOH in water at a molar ratio of 1:1 to 3.

[0010] Preferably, the molar ratio of Bi(NO3)3·5H2O to KI is 5 to 10:1.

[0011] Preferably, in step 1, the stirring time is 30 min to 1 h; the hydrothermal reaction temperature is 160 °C to 200 °C; and the hydrothermal reaction time is 20 h to 30 h.

[0012] Preferably, in step 2, the amount of nickel acetate is 2 mmol to 30 mmol; and the amount of oleylamine aqueous solution is 14 mL.

[0013] Preferably, in step 2, the temperature of the hydrothermal reaction is 280℃~300℃, and the time of the hydrothermal reaction is 3h~6h; in both steps 1 and 2, the drying is carried out in air at a temperature of 60℃ for 24h.

[0014] Preferably, the suspension containing Bi5O7I and Ni3C is obtained by placing the Bi5O7I obtained in step 1 and the Ni3C obtained in step 2 in deionized water and then subjecting them to ultrasonic treatment for 30 to 60 minutes; the Bi(NO3)3·5H2O solution is obtained by dissolving Bi(NO3)3·5H2O in 5 mL of glacial acetic acid.

[0015] Preferably, in step 3, the vigorous stirring time is 2h to 3h, the hydrothermal reaction temperature is 60℃ to 100℃, and the hydrothermal reaction time is 3h to 6h; in steps 1, 2, and 3, the washing is performed by alternating washing with deionized water and ethanol 6 to 10 times; in step 3, the vacuum drying is performed at a temperature of 60℃ for 12h to 24h.

[0016] Preferably, the Ni3C accounts for 7% of the mass of the Ni3C / Bi5O7I.

[0017] Secondly, the present invention provides an application of the Ni3C / Bi5O7I composite material for visible light catalytic degradation of phenol, wherein the Ni3C / Bi5O7I composite material obtained by the preparation method described in the first aspect is used for visible light catalytic degradation of phenol.

[0018] Compared with the prior art, the present invention has the following advantages:

[0019] This invention provides a method for preparing Ni3C / Bi5O7I composite material and its application, relating to the field of photocatalysis technology. The preparation method includes: Step 1: Adding KI to a suspension containing Bi(NO3)3·5H2O and NaOH, stirring, and then carrying out a hydrothermal reaction. The resulting product is cooled to room temperature, centrifuged, washed, and dried to obtain Bi5O7I; Step 2: Adding nickel acetate to an oleylamine aqueous solution under a nitrogen atmosphere, carrying out a hydrothermal reaction, cooling to room temperature, and the resulting precipitate is centrifuged, washed, and dried to obtain Ni3C; Step 3: Adding Bi(NO3)3·5H2O solution dropwise to a suspension containing Bi5O7I and Ni3C under vigorous stirring, and then carrying out a hydrothermal reaction. The resulting precipitate is centrifuged, washed, and vacuum dried to obtain Ni3C / Bi5O7I. This invention improves the photocatalytic activity of Bi5O7I by introducing Ni3C into it, and gives the resulting photocatalytic material the ability to efficiently and stably degrade phenol in water, which has potential application value in the field of phenol-containing wastewater purification.

[0020] This invention employs an in-situ hydrothermal synthesis method to combine Ni3C and Bi5O7I photocatalysts, yielding a binary composite nano-photocatalyst—the Ni3C / Bi5O7I photocatalyst. By combining the photocatalyst Bi5O7I, which possesses high photocatalytic activity and thermochemical stability, with nickel nanoparticles exhibiting plasmon resonance effects, the problem of low photocatalytic activity in Bi5O7I, which is limited by its low photon efficiency, is solved. The introduction of Ni3C enhances the photocatalytic activity of Bi5O7I. The visible light absorption range of the catalyst is expanded, which helps in the separation of photogenerated carriers and the narrowing of the band gap, thereby improving carrier transport efficiency and enhancing the photocatalytic activity of Bi5O7I. This results in a composite photocatalytic material with excellent photocatalytic activity and a highly efficient and stable ability to degrade phenol in water. The improved adsorption capacity of the composite photocatalytic material for phenol further enhances the degradation rate of phenol under visible light, making it an effective material for purifying phenol-containing wastewater. This invention has potential application value in the field of phenol-containing wastewater purification and realizes the construction of a novel, efficient, and environmentally friendly photocatalytic purification system for phenol-containing wastewater. The preparation method provided by this invention is simple and easy to operate. Furthermore, this photocatalytic nanocomposite material also exhibits better stability and reusability. Attached Figure Description

[0021] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0022] Figure 1 A flowchart illustrating the preparation method of the Ni3C / Bi5O7I composite material provided in this embodiment of the invention;

[0023] Figure 2 This is a SEM image of the Ni3C / Bi5O7I composite material obtained in Example 1 of this invention;

[0024] Figure 3 The N2 adsorption-desorption isotherm of the Ni3C / Bi5O7I composite material prepared in Example 1 of this invention;

[0025] Figure 4 Fourier transform infrared spectrum of the Ni3C / Bi5O7I composite material prepared in Example 1 of this invention;

[0026] Figure 5 The ultraviolet diffuse reflectance spectra of the materials prepared in Examples 1, 2, and 3 are shown below.

[0027] Figure 6 This is a comparison chart of the photocatalytic performance of the materials prepared in Examples 1-7 of this invention;

[0028] Figure 7 The figure shows the results of the continuous degradation experiment of the 7% Ni3C / Bi5O7I composite material prepared in Example 5. Detailed Implementation

[0029] The following embodiments are provided to better understand the present invention and are not limited to the preferred embodiments described. They do not constitute a limitation on the content and scope of protection of the present invention. Any product that is the same as or similar to the present invention, derived by any person under the guidance of the present invention or by combining the features of the present invention with other prior art, falls within the protection scope of the present invention.

[0030] Specific experimental steps or conditions are not specified in the embodiments; they can be performed according to the conventional experimental steps or conditions described in the prior art. Reagents and other instruments used, unless otherwise specified, are all commercially available conventional reagent products. Furthermore, the accompanying drawings are merely illustrative diagrams of the embodiments of this disclosure and are not necessarily drawn to scale. The same reference numerals in the drawings denote the same or similar parts, and therefore, repeated descriptions of them will be omitted. Some block diagrams shown in the drawings are functional entities and do not necessarily correspond to physically or logically independent entities.

[0031] Bi5O7I is a newly discovered visible-light-driven photocatalyst with an optical band gap of approximately 2.8 eV. Its unique layered crystal structure results in an internal electrostatic field perpendicular to each layer, thereby promoting the separation of photogenerated carriers. Therefore, Bi5O7I photocatalysts exhibit good photoactivity in the degradation of methyl orange (MO) in water and acetaldehyde (CH3CHO) in air. However, its insufficient light absorption and low carrier transport efficiency limit its photocatalytic activity. Therefore, improving the photocatalytic activity of Bi5O7I and efficiently degrading phenol has become an urgent technical problem to be solved.

[0032] In view of this, the present invention improves the photocatalytic activity of Bi5O7I by introducing Ni3C into Bi5O7I, and enables the photocatalytic material to efficiently and stably degrade phenol in water, making it an effective material for purifying phenol-containing wastewater. It has potential application value in the field of phenol-containing wastewater purification, and realizes the construction of a new, efficient and environmentally friendly photocatalytic purification system for phenol-containing wastewater, so as to solve the problem that the energy conversion efficiency of Bi5O7I is limited due to its low photon efficiency, thus resulting in low photocatalytic activity of Bi5O7I.

[0033] Firstly, referring to Figure 1 , Figure 1This is a flowchart illustrating a method for preparing the Ni3C / Bi5O7I composite material according to an embodiment of the present invention. The preparation method includes:

[0034] S101, KI was added to a suspension containing Bi(NO3)3·5H2O and NaOH and stirred, followed by a hydrothermal reaction. The resulting product was cooled to room temperature, centrifuged, washed and dried to obtain Bi5O7I.

[0035] S102, under a nitrogen atmosphere, nickel acetate was added to an aqueous solution of oleylamine and subjected to a hydrothermal reaction. After cooling to room temperature, the resulting precipitate was centrifuged, washed, and dried to obtain Ni3C.

[0036] S103, Bi(NO3)3·5H2O solution is added dropwise to a suspension containing Bi5O7I and Ni3C under vigorous stirring, followed by hydrothermal reaction. The resulting precipitate is centrifuged, washed, and vacuum dried to obtain Ni3C / Bi5O7I; wherein Ni3C accounts for 1% to 15% of the mass of Ni3C / Bi5O7I.

[0037] Ni3C is a good co-catalyst for Bi5O7I photocatalyst.

[0038] In practice, an excess of bismuth source is provided by the pentahydrate bismuth nitrate in the Bi(NO3)3·5H2O solution to prevent the precipitation of bismuth ions from Bi5O7I during the hydrothermal process, thus preventing the formation of the Ni3C / Bi5O7I composite material. The aforementioned Ni3C accounts for 1% to 15% of the mass of Ni3C / Bi5O7I, and this mass percentage is determined by the amount of nickel acetate.

[0039] In this invention, an in-situ hydrothermal synthesis method is used to combine Ni3C and Bi5O7I photocatalysts to obtain a binary composite nanophotocatalyst material—Ni3C / Bi5O7I photocatalyst. Bi5O7I is a semiconductor with a narrow bandgap and suitable band positions, thus exhibiting high photocatalytic activity and thermochemical stability. However, Bi5O7I suffers from low photon efficiency, which limits its energy conversion efficiency. Therefore, this invention solves the problem of low photon efficiency of Bi5O7I by introducing Ni3C: due to the plasmon resonance effect of nickel nanoparticles, the visible light absorption range of the Bi5O7I photocatalyst is improved, and it also helps in the separation of photogenerated carriers and the narrowing of the bandgap, thereby improving carrier transport efficiency and enhancing the photocatalytic activity of Bi5O7I. Furthermore, the preparation method provided by this invention is simple and easy to operate.

[0040] The prepared photocatalytic nanocomposite material, due to the introduction of Ni3C, exhibits excellent photocatalytic performance, thereby enhancing its adsorption capacity for phenol and subsequently increasing the degradation rate of phenol under visible light. This makes it potentially valuable for the purification of phenol-containing wastewater, realizing the construction of a novel, efficient, and environmentally friendly photocatalytic system for purifying phenol-containing wastewater. The catalyst, possessing the ability to efficiently and stably degrade phenol in water, becomes an effective material for purifying phenol-containing wastewater, addressing the problems of low photocatalytic activity and low phenol degradation efficiency in existing photocatalytic materials. This photocatalytic nanocomposite material also features better stability and reusability.

[0041] Preferably, in step 1, the suspension containing Bi(NO3)3·5H2O and NaOH is obtained by dissolving Bi(NO3)3·5H2O and NaOH in water at a molar ratio of 1:1 to 3.

[0042] In specific implementation, the preferred molar ratio of Bi(NO3)3·5H2O to NaOH is 1:3.

[0043] Preferably, the molar ratio of Bi(NO3)3·5H2O to KI is 5 to 10:1.

[0044] In specific implementation, the preferred molar ratio of Bi(NO3)3·5H2O to KI is 5:1.

[0045] Preferably, in step 1, the stirring time is 30 min to 1 h; the hydrothermal reaction temperature is 160 °C to 200 °C; and the hydrothermal reaction time is 20 h to 30 h.

[0046] In specific implementation, in step 1, the optimal stirring time is 30 minutes, the optimal temperature for the hydrothermal reaction is 180°C, and the optimal hydrothermal time is 24 hours.

[0047] Preferably, in step 2, the amount of nickel acetate is 2 mmol to 30 mmol; and the amount of oleylamine aqueous solution is 14 mL.

[0048] In specific implementation, the preferred amount of nickel acetate is 14 mmol, so that Ni3C accounts for 7% of the mass of the Ni3C / Bi5O7I composite material. It should be noted that the amount of oleylamine aqueous solution added is 14 mL.

[0049] Preferably, in step 2, the temperature of the hydrothermal reaction is 280℃~300℃, and the time of the hydrothermal reaction is 3h~6h; in both steps 1 and 2, the drying is carried out in air at a temperature of 60℃ for 24h.

[0050] In specific implementation, in step 2, the preferred temperature for the hydrothermal reaction is 300℃, and the preferred time for the hydrothermal reaction is 4 hours.

[0051] Preferably, the suspension containing Bi5O7I and Ni3C is obtained by placing the Bi5O7I obtained in step 1 and the Ni3C obtained in step 2 in deionized water and then subjecting them to ultrasonic treatment for 30 to 60 minutes; the Bi(NO3)3·5H2O solution is obtained by dissolving Bi(NO3)3·5H2O in 5 mL of glacial acetic acid.

[0052] Preferably, in step 3, the vigorous stirring time is 2h to 3h, the hydrothermal reaction temperature is 60℃ to 100℃, and the hydrothermal reaction time is 3h to 6h; in steps 1, 2, and 3, the washing is performed by alternating washing with deionized water and ethanol 6 to 10 times; in step 3, the vacuum drying is performed at a temperature of 60℃ for 12h to 24h.

[0053] In specific implementation, in step 3, the preferred temperature for the hydrothermal reaction is 80℃, and the preferred time for the hydrothermal reaction is 4 hours.

[0054] Preferably, the Ni3C accounts for 7% of the mass of the Ni3C / Bi5O7I.

[0055] In practice, experimental tests showed that when Ni3C accounted for 7% of the mass of the Ni3C / Bi5O7I composite material, its catalytic activity was the best and its degradation efficiency was the highest.

[0056] Secondly, the present invention provides an application of the Ni3C / Bi5O7I composite material for visible light catalytic degradation of phenol, wherein the Ni3C / Bi5O7I composite material obtained by the preparation method described in the first aspect is used for visible light catalytic degradation of phenol.

[0057] In this embodiment of the invention, the provided photocatalytic nanocomposite material exhibits excellent photocatalytic performance, thereby improving the adsorption capacity of the photocatalytic material for phenol. This makes the catalyst, which has the ability to efficiently and stably degrade phenol in water, an effective material for purifying phenol-containing wastewater, thus solving the problems of low photocatalytic activity and low phenol degradation efficiency of existing photocatalytic materials. This photocatalytic nanocomposite material features a higher phenol degradation rate under visible light, better stability, and reusability, demonstrating potential application value in the field of phenol-containing wastewater purification and realizing the construction of a novel, efficient, and environmentally friendly photocatalytic purification system for phenol-containing wastewater.

[0058] To enable those skilled in the art to better understand the present invention, the preparation method provided by the present invention will be described below through several specific embodiments.

[0059] The raw materials and reagents used in the following embodiments of this invention are all commercially available products. Specifically, sodium hydroxide (NaOH), nickel acetate (Ni(CH3COO)2), bismuth nitrate pentahydrate (Bi(NO3)3·5H2O), glacial acetic acid (CH3COOH), and potassium iodide (KI) were all purchased from Aladdin (Shanghai, China). All reagents can be used without further purification, and deionized water was used in all experiments. It should be noted that, unless otherwise specified, all operations involved are standard procedures in the art.

[0060] Example 1

[0061] Bi(NO3)3·5H2O and NaOH in a molar ratio of 1:3 were dissolved in 50 mL of water to form a white suspension. KI (with a molar ratio of Bi(NO3)3·5H2O to KI of 5:1) was then added to the suspension. After stirring for 30 min, the suspension was transferred to a 100 mL high-pressure reactor lined with polytetrafluoroethylene (PTFE). The high-pressure reactor was then sealed in a stainless steel container for a hydrothermal reaction at 180 °C for 24 h. After the reactor cooled naturally to room temperature, it was centrifuged and washed three times with deionized water. After washing, it was dried in air at 60 °C for 24 h to obtain Bi5O7I.

[0062] Under a nitrogen atmosphere, 2 mmol of nickel acetate was added to 14 mL of oleylamine aqueous solution and a hydrothermal reaction was carried out at a temperature of 300 °C for 4 h. After the reaction, the solution was cooled to room temperature (25 °C), the precipitate was centrifuged, and then washed with ethanol, hexane and acetone. Finally, the product was dried under vacuum at 60 °C to obtain Ni3C.

[0063] The Bi5O7I and Ni3C obtained above were placed in 60 mL of deionized water and sonicated for 30 min to obtain a suspension containing Bi5O7I and Ni3C. A specific mass (485 mg) of bismuth nitrate pentahydrate (Bi(NO3)3·5H2O) was dissolved in 5 mL of glacial acetic acid to obtain a Bi(NO3)3·5H2O solution. The Bi(NO3)3·5H2O solution was added dropwise to the suspension containing Bi5O7I and Ni3C under vigorous stirring for 2 h. The resulting mixture was transferred to a polytetrafluoroethylene stainless steel autoclave for hydrothermal reaction at 80 °C for 4 h. After the reaction was completed, the precipitate was centrifuged, washed repeatedly, and vacuum dried to obtain 1% Ni3C / Bi5O7I.

[0064] The material obtained in Example 1 was characterized, referring to... Figure 2 , Figure 2This is a SEM image of the Ni3C / Bi5O7I composite material obtained in Example 1 of this invention. Figure 2 As shown, the square nanosheet structure is Bi5O7I, with a small amount of Ni3C particles dotted on the surface of the Bi5O7I (square nanosheet structure). (Refer to...) Figure 3 , Figure 3 This is the N2 adsorption-desorption isotherm diagram of the Ni3C / Bi5O7I composite material prepared in Example 1 of this invention. Figure 3 As shown, the specific surface area of ​​the composite material is 12.64 m². 2 The g / g indicates that the physical adsorption of the composite material is poor. In the microstructure of the Ni3C / Bi5O7I composite material provided by this invention, the ultrathin nanosheets aggregate, resulting in a very weak interaction between the adsorbent and adsorbate, leading to poor adsorption of organic pollutants. Furthermore, the Ni3C / Bi5O7I composite material provided by this invention mainly undergoes redox reactions (chemisorption) rather than physical adsorption in the photocatalytic degradation of organic pollutants. To study the composition and structure of the synthesized sample, FTIR analysis was performed, referring to... Figure 4 , Figure 4 The Fourier transform infrared spectrum of the Ni3C / Bi5O7I composite material prepared in Example 1 of this invention is shown. For Bi5O7I, the spectrum is at 500 cm⁻¹. -1 There is an absorption peak nearby, which corresponds to the absorption peak caused by the Bi-O stretching vibration; for Ni3C, no obvious absorption peak was observed, possibly due to the low doping amount, which indicates the successful synthesis of Ni3C / Bi5O7I composite catalyst.

[0065] Example 2 (Comparative Example 1 of Example 1)

[0066] Bi(NO3)3·5H2O and NaOH in a molar ratio of 1:3 were dissolved in 50 mL of water to form a white suspension. KI (with a molar ratio of Bi(NO3)3·5H2O to KI of 5:1) was then added to the suspension. After stirring for 30 min, the suspension was transferred to a 100 mL high-pressure reactor lined with polytetrafluoroethylene (PTFE). The high-pressure reactor was then sealed in a stainless steel container for a hydrothermal reaction at 180 °C for 24 h. After the reactor cooled naturally to room temperature, it was centrifuged and washed three times with deionized water. After washing, it was dried in air at 60 °C for 24 h to obtain Bi5O7I.

[0067] Example 3 (Comparative Example 2 of Example 1)

[0068] Under a nitrogen atmosphere, 2 mmol of nickel acetate was added to 14 mL of oleylamine aqueous solution and a hydrothermal reaction was carried out at a temperature of 300 °C for 4 h. After the reaction, the solution was cooled to room temperature (25 °C), the precipitate was centrifuged, and then washed with ethanol, hexane and acetone. Finally, the product was dried under vacuum at 60 °C to obtain Ni3C.

[0069] The three materials obtained above—1% Ni3C / Bi5O7I, Bi5O7I, and Ni3C—were subjected to ultraviolet diffuse reflectance testing, and their spectra were obtained. (Refer to...) Figure 5 , Figure 5 The images show the diffuse ultraviolet reflectance spectra of the materials prepared in Examples 1, 2, and 3. Figure 3 As shown, pure Bi5O7I (Comparative Example 1) begins to absorb at 452 nm, which corresponds precisely to the band gap of 2.74 eV determined by the Kubelka-Munk theory. Similarly, the band gap energy of Ni3C (Comparative Example 2) is 2.68 eV. It is evident that the two materials have similar band gap energies, which in turn leads to similar light absorption properties in the Ni3C / Bi5O7I composite material. However, for the sample of Example 1 (1% Ni3C / Bi5O7I), a new absorption peak is observed at 550 nm. Considering that the Ni3C sample (Comparative Example 2) also shows a peak, and no change was observed in the UV-vis spectrum of the Bi5O7I used, the strong absorption can be attributed to the surface plasmon absorption of the formed Ni nanoparticles.

[0070] Example 4

[0071] The difference between this embodiment and Example 1 is that the amount of nickel acetate is different, resulting in a different mass ratio of Ni3C in Ni3C / Bi5O7I.

[0072] Bi(NO3)3·5H2O and NaOH in a molar ratio of 1:3 were dissolved in 50 mL of water to form a white suspension. KI (with a molar ratio of Bi(NO3)3·5H2O to KI of 5:1) was then added to the suspension. After stirring for 30 min, the suspension was transferred to a 100 mL high-pressure reactor lined with polytetrafluoroethylene (PTFE). The high-pressure reactor was then sealed in a stainless steel container for a hydrothermal reaction at 180 °C for 24 h. After the reactor cooled naturally to room temperature, it was centrifuged and washed three times with deionized water. After washing, it was dried in air at 60 °C for 24 h to obtain Bi5O7I.

[0073] Under a nitrogen atmosphere, 10 mmol of nickel acetate was added to 14 mL of oleylamine aqueous solution and a hydrothermal reaction was carried out at a temperature of 300 °C for 4 h. After the reaction, the solution was cooled to room temperature (25 °C), the precipitate was centrifuged, and then washed with ethanol, hexane and acetone. Finally, the product was dried under vacuum at 60 °C to obtain Ni3C.

[0074] The Bi5O7I and Ni3C obtained above were placed in 60 mL of deionized water and sonicated for 30 min to obtain a suspension containing Bi5O7I and Ni3C. A specific mass of bismuth nitrate pentahydrate (Bi(NO3)3·5H2O) was dissolved in 5 mL of glacial acetic acid to obtain a Bi(NO3)3·5H2O solution. The Bi(NO3)3·5H2O solution was added dropwise to the suspension containing Bi5O7I and Ni3C under vigorous stirring for 2 h. The resulting mixture was transferred to a polytetrafluoroethylene stainless steel autoclave for hydrothermal reaction at 80 °C for 4 h. After the reaction was completed, the precipitate was centrifuged, washed repeatedly, and vacuum dried to obtain 5% Ni3C / Bi5O7I.

[0075] Example 5

[0076] The difference between this embodiment and Example 1 is that the amount of nickel acetate is different, resulting in a different mass ratio of Ni3C in Ni3C / Bi5O7I.

[0077] Bi(NO3)3·5H2O and NaOH in a molar ratio of 1:3 were dissolved in 50 mL of water to form a white suspension. KI (with a molar ratio of Bi(NO3)3·5H2O to KI of 5:1) was then added to the suspension. After stirring for 30 min, the suspension was transferred to a 100 mL high-pressure reactor lined with polytetrafluoroethylene (PTFE). The high-pressure reactor was then sealed in a stainless steel container for a hydrothermal reaction at 180 °C for 24 h. After the reactor cooled naturally to room temperature, it was centrifuged and washed three times with deionized water. After washing, it was dried in air at 60 °C for 24 h to obtain Bi5O7I.

[0078] Under a nitrogen atmosphere, 14 mmol of nickel acetate was added to 14 mL of oleylamine aqueous solution and a hydrothermal reaction was carried out at a temperature of 300 °C for 4 h. After the reaction, the solution was cooled to room temperature (25 °C), the precipitate was centrifuged, and then washed with ethanol, hexane and acetone. Finally, the product was dried under vacuum at 60 °C to obtain Ni3C.

[0079] The Bi5O7I and Ni3C obtained above were placed in 60 mL of deionized water and sonicated for 30 min to obtain a suspension containing Bi5O7I and Ni3C. A specific mass of bismuth nitrate pentahydrate (Bi(NO3)3·5H2O) was dissolved in 5 mL of glacial acetic acid to obtain a Bi(NO3)3·5H2O solution. The Bi(NO3)3·5H2O solution was added dropwise to the suspension containing Bi5O7I and Ni3C under vigorous stirring for 2 h. The resulting mixture was transferred to a polytetrafluoroethylene stainless steel autoclave for hydrothermal reaction at 80 °C for 4 h. After the reaction was completed, the precipitate was centrifuged, washed repeatedly, and vacuum dried to obtain 7% Ni3C / Bi5O7I.

[0080] Example 6

[0081] The difference between this embodiment and Example 1 is that the amount of nickel acetate is different, resulting in a different mass ratio of Ni3C in Ni3C / Bi5O7I.

[0082] Bi(NO3)3·5H2O and NaOH in a molar ratio of 1:3 were dissolved in 50 mL of water to form a white suspension. KI (with a molar ratio of Bi(NO3)3·5H2O to KI of 5:1) was then added to the suspension. After stirring for 30 min, the suspension was transferred to a 100 mL high-pressure reactor lined with polytetrafluoroethylene (PTFE). The high-pressure reactor was then sealed in a stainless steel container for a hydrothermal reaction at 180 °C for 24 h. After the reactor cooled naturally to room temperature, it was centrifuged and washed three times with deionized water. After washing, it was dried in air at 60 °C for 24 h to obtain Bi5O7I.

[0083] Under a nitrogen atmosphere, 18 mmol of nickel acetate was added to 14 mL of oleylamine aqueous solution and a hydrothermal reaction was carried out at a temperature of 300 °C for 4 h. After the reaction, the solution was cooled to room temperature (25 °C), the precipitate was centrifuged, and then washed with ethanol, hexane and acetone. Finally, the product was dried under vacuum at 60 °C to obtain Ni3C.

[0084] The Bi5O7I and Ni3C obtained above were placed in 60 mL of deionized water and sonicated for 30 min to obtain a suspension containing Bi5O7I and Ni3C. A specific mass of bismuth nitrate pentahydrate (Bi(NO3)3·5H2O) was dissolved in 5 mL of glacial acetic acid to obtain a Bi(NO3)3·5H2O solution. The Bi(NO3)3·5H2O solution was added dropwise to the suspension containing Bi5O7I and Ni3C under vigorous stirring for 2 h. The resulting mixture was transferred to a polytetrafluoroethylene stainless steel autoclave for hydrothermal reaction at 80 °C for 4 h. After the reaction was completed, the precipitate was centrifuged, washed repeatedly, and vacuum dried to obtain 9% Ni3C / Bi5O7I.

[0085] Example 7

[0086] The difference between this embodiment and Example 1 is that the amount of nickel acetate is different, resulting in a different mass ratio of Ni3C in Ni3C / Bi5O7I.

[0087] Bi(NO3)3·5H2O and NaOH in a molar ratio of 1:3 were dissolved in 50 mL of water to form a white suspension. KI (with a molar ratio of Bi(NO3)3·5H2O to KI of 5:1) was then added to the suspension. After stirring for 30 min, the suspension was transferred to a 100 mL high-pressure reactor lined with polytetrafluoroethylene (PTFE). The high-pressure reactor was then sealed in a stainless steel container for a hydrothermal reaction at 180 °C for 24 h. After the reactor cooled naturally to room temperature, it was centrifuged and washed three times with deionized water. After washing, it was dried in air at 60 °C for 24 h to obtain Bi5O7I.

[0088] Under a nitrogen atmosphere, 30 mmol of nickel acetate was added to 14 mL of oleylamine aqueous solution and a hydrothermal reaction was carried out at a temperature of 300 °C for 4 h. After the reaction, the solution was cooled to room temperature (25 °C), the precipitate was centrifuged, and then washed with ethanol, hexane and acetone. Finally, the product was dried under vacuum at 60 °C to obtain Ni3C.

[0089] The Bi5O7I and Ni3C obtained above were placed in 60 mL of deionized water and sonicated for 30 min to obtain a suspension containing Bi5O7I and Ni3C. A specific mass of bismuth nitrate pentahydrate (Bi(NO3)3·5H2O) was dissolved in 5 mL of glacial acetic acid to obtain a Bi(NO3)3·5H2O solution. The Bi(NO3)3·5H2O solution was added dropwise to the suspension containing Bi5O7I and Ni3C under vigorous stirring for 2 h. The resulting mixture was transferred to a polytetrafluoroethylene stainless steel autoclave for hydrothermal reaction at 80 °C for 4 h. After the reaction was completed, the precipitate was centrifuged, washed repeatedly, and vacuum dried to obtain 15% Ni3C / Bi5O7I.

[0090] The degradation performance of the materials prepared in Examples 1 to 7 on phenol was verified:

[0091] Evaluation of photocatalytic activity:

[0092] The photocatalytic degradation of phenol was carried out in a self-made photochemical reactor equipped with a 350W xenon lamp. The xenon lamp was combined with two filters to block ultraviolet and infrared light. All photocatalytic reactions were conducted under the same initial conditions: 100 mL of a reaction solution containing 10 mg / L phenol was mixed with the material prepared in Examples 1 to 7 (1.0 g / L) under constant magnetic stirring; the solution containing the photocatalyst was stirred for 1 hour before irradiation to allow the system to reach adsorption-desorption equilibrium; approximately 5 mL of suspension was collected at given irradiation intervals, and the solids were subsequently removed from the solution by centrifugation for further analysis. The concentration of the aqueous phenol solution was determined by measuring the maximum absorbance at 554 nm using a UV-Vis spectrophotometer. (Reference) Figure 6 , Figure 6The graph shows a comparison of the photocatalytic performance of the materials prepared in Examples 1-7 of this invention. In the graph, the curves from top to bottom (between times 30-60) are, in order: Blank, Ni3C, Bi5O7I, 1% Ni3C / Bi5O7I, 15% Ni3C / Bi5O7I, 9% Ni3C / Bi5O7I, 5% Ni3C / Bi5O7I, and 7% Ni3C / Bi5O7I. It can be observed from the graph that the self-degradation of phenol is negligible in the absence of a photocatalyst (Blank). When pure Bi5O7I sample was added to the phenol solution, the phenol content decreased by approximately 13% during the adsorption experiment; after xenon lamp irradiation, the phenol concentration further decreased with increasing visible light irradiation time. The degradation rate of Ni3C is slightly lower than that of Bi5O7I, but its adsorption capacity for phenol is higher. Compared with pure Bi5O7I or Ni3C, the Ni3C / Bi5O7I hybrid (Ni3C / Bi5O7I composite material) exhibits significantly enhanced adsorption and degradation capabilities for phenol. The Ni3C nanoparticles formed on the surface of Bi5O7I microrods are the reason for the increased phenol adsorption. The improved photocatalytic activity can be attributed to the improved electron-hole pair separation efficiency and enhanced visible light absorption performance. As the Ni3C addition increases from 1% to 15%, the photocatalytic activity first increases and then decreases. Experimental tests show that the 7% Ni3C / Bi5O7I sample exhibits the highest phenol degradation efficiency under visible light irradiation.

[0093] Continuous degradation experiment:

[0094] After the first degradation reaction was completed, the catalyst was separated from the solution with the aid of centrifugation, washed three times with deionized water and ethanol respectively, and then dried in a freeze dryer for 12 hours before storage. The stored material was then used for the second degradation reaction, with all reaction conditions remaining the same as the first reaction except for the material itself. After the second reaction was completed, the above steps were repeated for the sixth degradation experiment, and the results are as follows: Figure 7 As shown. (Refer to...) Figure 7 , Figure 7 The figure shows the continuous degradation results of the 7% Ni3C / Bi5O7I composite material prepared in Example 5. As can be seen from the figure, the Ni3C / Bi5O7I composite photocatalytic nanomaterial exhibits stable photocatalytic performance. In each repeated cycle, the degradation rate of phenol did not show any significant decrease, and the photocatalyst remained rapid and effective in removing phenol even after 6 cycles, indicating that the catalyst has high reusability.

[0095] For the sake of simplicity, the method embodiments are described as a series of actions. However, those skilled in the art should understand that the present invention is not limited to the described order of actions, as some steps can be performed in other orders or simultaneously according to the present invention. Furthermore, those skilled in the art should also understand that the embodiments described in the specification are preferred embodiments, and the actions and components involved are not necessarily essential to the present invention.

[0096] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of this disclosure. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. In addition, those skilled in the art can combine and integrate the different embodiments or examples described in this specification.

[0097] The preparation method and application of the Ni3C / Bi5O7I composite material provided by the present invention have been described in detail above. Specific examples have been used to illustrate the principle and implementation of the present invention. The description of the above embodiments is only for the purpose of helping to understand the method and core idea of ​​the present invention. At the same time, for those skilled in the art, there will be changes in the specific implementation and application scope based on the idea of ​​the present invention. Therefore, the content of this specification should not be construed as a limitation of the present invention.

Claims

1. A method for preparing a Ni3C / Bi5O7I composite material, characterized in that, The preparation method includes: Step 1: Add KI to a suspension containing Bi(NO3)3·5H2O and NaOH and stir. Then carry out a hydrothermal reaction. After cooling to room temperature, centrifuge, wash and dry the product to obtain Bi5O7I. Step 2: Under a nitrogen atmosphere, nickel acetate was added to an aqueous solution of oleylamine and subjected to a hydrothermal reaction. After cooling to room temperature, the resulting precipitate was centrifuged, washed, and dried to obtain Ni3C. Step 3: Bi(NO3)3·5H2O solution is added dropwise to a suspension containing Bi5O7I and Ni3C under vigorous stirring, followed by a hydrothermal reaction. The resulting precipitate is centrifuged, washed, and vacuum dried to obtain Ni3C / Bi5O7I; wherein Ni3C accounts for 1% to 15% of the mass of Ni3C / Bi5O7I. In step 1, the suspension containing Bi(NO3)3·5H2O and NaOH is obtained by dissolving Bi(NO3)3·5H2O and NaOH in water at a molar ratio of 1:1~3; In step 2, the amount of nickel acetate is 2 mmol to 30 mmol; the amount of oleylamine aqueous solution is 14 mL; In step 2, the temperature of the hydrothermal reaction is 280 ℃~300 ℃, and the time of the hydrothermal reaction is 3 h~6 h.

2. The preparation method according to claim 1, characterized in that, The molar ratio of Bi(NO3)3·5H2O to KI is 5~10:

1.

3. The preparation method according to claim 1, characterized in that, In step 1, the stirring time is 30 min to 1 h; the hydrothermal reaction temperature is 160 ℃ to 200 ℃; and the hydrothermal reaction time is 20 h to 30 h.

4. The preparation method according to claim 1, characterized in that, In both steps 1 and 2, the drying process involves drying in air at a temperature of 60 °C for 24 hours.

5. The preparation method according to claim 1, characterized in that, The suspension containing Bi5O7I and Ni3C is obtained by placing Bi5O7I obtained in step 1 and Ni3C obtained in step 2 in deionized water and then subjecting them to ultrasonic treatment for 30 min to 60 min; the Bi(NO3)3·5H2O solution is obtained by dissolving Bi(NO3)3·5H2O in 5 mL of glacial acetic acid.

6. The preparation method according to claim 1, characterized in that, In step 3, the vigorous stirring time is 2 h to 3 h, the hydrothermal reaction temperature is 60 ℃ to 100 ℃, and the hydrothermal reaction time is 3 h to 6 h; in steps 1, 2, and 3, the washing is performed by alternating washing with deionized water and ethanol 6 to 10 times; in step 3, the vacuum drying is performed at a temperature of 60 ℃ for 12 h to 24 h.

7. The preparation method according to claim 1, characterized in that, The Ni3C accounts for 7% of the mass of the Ni3C / Bi5O7I.

8. The application of Ni3C / Bi5O7I composite material in visible light photocatalytic degradation of phenol, characterized in that, The Ni3C / Bi5O7I composite material obtained by the preparation method according to any one of claims 1-7 is used for visible light catalytic degradation of phenol.

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