Method for improving photocatalytic antibacterial performance of ternary metal sulfide based on A-site deletion strategy

Abstract

The invention discloses a method for improving the photocatalytic antibacterial performance of ternary metal sulfide based on an A-site deletion strategy, which comprises the following steps: firstly, according to the molar ratio of A-site metal ions to indium ions of x: 2, wherein 0 lt; xlt; the method comprises the following steps: 1, selecting and weighing a corresponding A-site metal source, an indium source and a sulfur source according to an adaptive proportion of sulfur ions; the method comprises the following steps: dissolving an A-site metal source and an indium source in deionized water, stirring at room temperature for 30 minutes to obtain a mixed solution, adding a sulfur source, and stirring until the sulfur source is dissolved into a precursor solution; vigorously stirring and reacting the precursor solution in an oil bath at 80-120 DEG C for 3-8 hours to obtain a turbid liquid, centrifuging for 5-30 minutes at 3000-8000 r.p.m., collecting precipitates, cleaning for 2-5 times, and dispersing; and performing ultrasonic treatment for 0.5-5 hours at 200-300 W, and centrifuging to take clear liquid, thereby obtaining the AxIn2S3 + x material. The method does not need special equipment and harsh conditions, and is simple in process, high in controllability and easy to realize large-scale production.

Description

Technical Field

[0001] This invention relates to the field of photocatalytic antibacterial materials technology, and in particular to a method for improving the photocatalytic antibacterial performance of ternary metal sulfides based on an A-site deletion strategy. Background Technology

[0002] Pathogenic bacteria (such as Escherichia coli, Staphylococcus aureus, and Pseudomonas aeruginosa) and viruses (such as swine influenza H1N1 and human coronaviruses) pose a serious threat to public health. Traditional disinfection methods, such as ozone, ultraviolet irradiation, chlorination, and antibacterial agents, consume large amounts of energy and have many side effects (toxic byproducts, antibiotic resistance, etc.), which are unfavorable from a long-term sustainability perspective. In contrast, photocatalytic disinfection technology is considered a promising alternative to traditional disinfection techniques due to its green, safe, and long-term effectiveness.

[0003] Since Matsunaga et al. first reported the photocatalytic bactericidal effect of TiO2 in 1985, the study of photocatalytic bactericidal performance based on semiconductors has attracted widespread attention from scholars. This technology utilizes electron-hole pairs generated by photoexcitation and reactive oxygen species (·O2) - ·OH and 1 Photocatalysis employs multiple oxidative damage mechanisms (such as O2) on bacterial cell membranes, proteins, and genetic material, resulting in irreversible inactivation of microorganisms. Compared to traditional chemical disinfection methods, photocatalysis offers advantages such as long-lasting effects, environmental friendliness, and highly efficient antibacterial activity, making it a green antibacterial technology with great development potential.

[0004] However, current photocatalytic antibacterial materials still face the following challenges: (1) Limited spectral response range: Due to the wide bandgap characteristic of 3.2 eV, mainstream TiO2-based materials can only be activated in the ultraviolet spectral region (< 387 nm), while ultraviolet light accounts for only 4% of the solar spectrum, which seriously restricts the photon utilization rate; (2) High carrier recombination rate: The photogenerated electron-hole pairs of traditional photocatalysts recombine quickly, resulting in low photocatalytic efficiency, which is a key factor restricting the photocatalytic sterilization efficiency; (3) Insufficient sterilization efficiency against drug-resistant bacteria: With the emergence of superbugs caused by the overuse of antibiotics, the existing materials have poor inactivation efficiency against pathogens such as drug-resistant Staphylococcus aureus. Therefore, it is of great significance to develop efficient and stable photocatalytic antibacterial materials with visible light absorption.

[0005] Metal sulfides, due to their suitable conduction band (CB) position, relatively narrow band gap, and relatively good chemical stability, are a class of promising visible-light photocatalytic antibacterial materials. Among them, ternary metal sulfides, with their diverse structures, rich elemental composition, and tunable antibacterial properties, have significant advantages over traditional binary sulfides and are considered next-generation photocatalytic antibacterial materials. However, for common ternary metal sulfides such as ZnIn2S4, MgIn2S4, and CaIn2S4, their wide band gap and poor photogenerated carrier separation ability result in low visible light utilization and less generation of reactive oxygen species, thus limiting their application in the field of photocatalytic antibacterial (see ACS Applied Materials Interfaces, 2015, Vol. 7, pp. 16440-16449). Therefore, improving the light absorption performance of ternary metal sulfides and enhancing the separation ability of photogenerated carriers are key to achieving efficient antibacterial activity.

[0006] Current modification strategies for ternary metal sulfides mainly revolve around doping, heterojunction construction, noble metal co-catalyst deposition, and S-vacancy construction. For example, Chinese patent document CN111437834A discloses a method for constructing in-situ heterostructures based on ZnIn2S4 nanosheets. Using zinc acetate dihydrate and indium chloride tetrahydrate as raw materials, thioacetamide as the sulfur source, and deionized water and ethanol as solvents, In2O3@ZnIn2S4 and In(OH)3@ZnIn2S4 heterostructures were constructed in-situ in an ammonia solution. This effectively suppressed the recombination of photogenerated electron-hole pairs and exhibited excellent performance in photocatalytic CO2 reduction. However, the construction of heterostructures usually requires high requirements for the band structure and interface matching of the material. (Journal of Materials Chemistry) A, Volume 13, Issue 23, pp. 17646-17657, reports a solid-state decomposition method that incorporates Mn from α-MnO2 into ZnIn2S4. When the Mn doping amount is 0.25%, the antibacterial efficiency against *Escherichia coli* and *Staphylococcus aureus* is increased by 9.64% and 23.53%, respectively. However, doping can also lead to defect formation, which, as recombination centers for photogenerated charge carriers, affects photocatalytic efficiency. *Applied Catalysis B: Environmental*, 2018, Volume 237, pp. 970-975, reports the use of photoreduction to load Pd nanoparticles as a co-catalyst onto ZnIn2S4, effectively improving its photocatalytic efficiency. However, the introduction of the noble metal co-catalyst also leads to increased costs. *Journal of the American Chemical Society* Society, 2023, Vol. 145, No. 50, pp. 27757–27766, reported a strategy of constructing ZnIn2S4 containing S vacancies by calcining in air, which effectively promoted the separation of photogenerated electrons and holes, thereby improving the efficiency of photocatalytic H2O2 production. However, the presence of defect energy levels may also promote the recombination of photogenerated carriers, which is not conducive to the photocatalytic reaction.

[0007] Based on the advantages and disadvantages of the above strategies, this application proposes a novel strategy: A-site ion deletion to improve photocatalytic sterilization efficiency. The deletion of A-site cations causes a red shift in the absorption edge of the material, reducing the band gap and improving the material's light absorption performance. Simultaneously, the deletion of A-site cations promotes the separation of photogenerated carriers, ensuring their full utilization and facilitating the generation of reactive oxygen species, thereby achieving highly efficient photocatalytic antibacterial activity. Specifically, Zn... 0.7 In2S 3.7 It exhibits excellent photocatalytic antibacterial properties, effectively killing Escherichia coli within 10 minutes, Staphylococcus aureus within 20 minutes, and drug-resistant Staphylococcus aureus within 30 minutes. Summary of the Invention

[0008] In order to overcome the shortcomings and deficiencies of the existing technology, the present invention provides a method for improving the photocatalytic antibacterial performance of ternary metal sulfides based on the A-site deletion strategy.

[0009] The technical solution adopted in this invention is a method for improving the photocatalytic antibacterial performance of ternary metal sulfides based on an A-site deletion strategy, comprising the following steps:

[0010] S1: Select an A-site metal source, an indium source, and a sulfur source. The A-site metal source is one of zinc acetate, zinc nitrate, zinc sulfate, magnesium acetate, magnesium nitrate, magnesium sulfate, calcium acetate, calcium nitrate, or calcium sulfate. The indium source is indium nitrate or indium chloride. The sulfur source is thioacetamide or cysteine. The molar ratio of A-site metal ion to indium ion is x : 2 (0 < x < 1), corresponding to A... x In2S 3+x The ratio of the total valence states of sulfide ions to A-site metal ions and indium ions was determined by weighing each raw material.

[0011] S2: Add the weighed A-site metal source and indium source to deionized water, stir at room temperature for 30 min to fully dissolve and mix the A-site metal source and indium source to form a mixed solution.

[0012] S3: Add the weighed sulfur source to the mixed solution obtained in S2, and continue stirring until the sulfur source is completely dissolved to obtain the reaction precursor solution;

[0013] S4: Transfer the reaction precursor liquid obtained in S3 to an oil bath, control the oil bath temperature at 80-120 ℃, and stir vigorously at the same time. Maintain this temperature and stirring state for 3-8 h to generate a suspension containing ternary metal sulfide precipitate.

[0014] S5: Centrifuge the suspension obtained in S4. Set the centrifuge speed to 3000-8000 rpm and the centrifugation time to 5-30 min. Collect the precipitate at the bottom after centrifugation. Wash the precipitate 2-5 times with deionized water or ethanol. Then redisperse the washed precipitate in deionized water to form a dispersion.

[0015] S6: The dispersion obtained in S5 was subjected to ultrasonic exfoliation. The ultrasonic power was set to 200-300 W and the ultrasonic time was 0.5-5 h. After ultrasonication, it was centrifuged again with the same centrifugation parameters as in S5. The supernatant was taken, which is the ternary metal sulfide A missing at site A. x In2S 3+x Photocatalytic materials.

[0016] Furthermore, S1 includes the following sub-steps:

[0017] S1.1: Determine the target product Ax In2S 3+x For the type of A, if A is Zn, then one of zinc acetate, zinc nitrate, and zinc sulfate is selected as the metal source at the A site; if A is Mg, then one of magnesium acetate, magnesium nitrate, and magnesium sulfate is selected as the metal source at the A site; if A is Ca, then one of calcium acetate, calcium nitrate, and calcium sulfate is selected as the metal source at the A site.

[0018] S1.2: Based on the target x value, 0 < x < 1, calculate the molar amounts of the metal source and indium source at site A to ensure that the molar ratio of metal ions to indium ions at site A is accurate to x : 2, wherein the indium source is selected from either indium nitrate or indium chloride.

[0019] S1.3: Based on the total molar number of metal ions and indium ions at site A, calculate the amount of sulfur source to be used, such that the molar number of sulfur ions and the total molar number of metal ions and indium ions at site A satisfy A. x In2S 3+x The stoichiometric ratio, the sulfur source is selected from either thioacetamide or cysteine;

[0020] S1.4: Using a weighing instrument with the required accuracy, weigh the calculated amounts of the metal source at position A, the indium source, and the sulfur source, and place each raw material in a clean container for later use.

[0021] Furthermore, S2 includes the following sub-steps:

[0022] S2.1: Select a clean reaction vessel and add a set volume of deionized water to it. The volume of deionized water should meet the requirements for subsequent raw material dissolution and reaction, which is 250 mL.

[0023] S2.2: Slowly add the metal source at site A weighed in S1 into the reaction vessel containing deionized water, turn on the stirring device, and set the stirring speed to a value that can fully dissolve the raw materials without producing too much foam. Observe the dissolution of the metal source at site A during the stirring process until it is completely dissolved.

[0024] S2.3: After the metal source at site A has completely dissolved, slowly add the indium source weighed in S1 into the solution in the reaction vessel, keep the stirring device running continuously, avoid splashing the solution during the stirring process, and ensure that the indium source is evenly dispersed in the solution;

[0025] S2.4: Stir continuously for 30 min, and observe the solution state regularly during this period to ensure that the metal source at site A and the indium source are completely dissolved, and that the solution is uniformly mixed without obvious particles or stratification, forming a homogeneous mixed solution.

[0026] Furthermore, S3 includes the following sub-steps:

[0027] S3.1: Keep the stirring device running in S2, and slowly add the sulfur source weighed in S1 to the mixed solution obtained in S2. Control the addition rate of the sulfur source during the addition process to avoid precipitation caused by excessively high local concentration due to excessive addition.

[0028] S3.2: After the sulfur source is completely added, continue stirring at the same speed as in S2 to ensure that the sulfur source is evenly dispersed in the mixed solution. At the same time, observe whether there are any abnormal phenomena in the solution, such as sudden color change or the formation of flocculent matter.

[0029] S3.3: Continue stirring for a period of time until the sulfur source is completely dissolved. Observe with the naked eye whether the solution is transparent and free of solid particles. If there are still undissolved sulfur source particles, the stirring rate can be increased or the stirring time can be extended appropriately.

[0030] S3.4: After the sulfur source is completely dissolved, the reaction precursor solution is obtained. Stop stirring and let the reaction precursor solution stand for a while to observe whether a precipitate is formed. If a precipitate is formed, it needs to be stirred again until the precipitate is dissolved to ensure that the reaction precursor solution is uniform and stable.

[0031] Furthermore, S4 includes the following sub-steps:

[0032] S4.1: Set the temperature of the oil bath to a specific value between 80-120 ℃, turn on the oil bath heating device, and after the oil bath temperature stabilizes at the set value, put the reaction vessel containing the reaction precursor liquid obtained in S3 into the oil bath, ensuring that the bottom of the reaction vessel is completely submerged in the oil bath.

[0033] S4.2: Turn on the stirring device and adjust the stirring speed to a vigorous stirring state to ensure that the reaction precursor solution is fully mixed during the reaction process to avoid uneven local reaction. At the same time, record the reaction start time.

[0034] S4.3: During the reaction, regularly observe the state of the solution in the reaction vessel, including color changes, whether precipitation is formed and the amount of precipitation. At the same time, monitor the temperature of the oil bath to ensure that the temperature is stable at the set value. If the temperature fluctuates, adjust the oil bath parameters in time.

[0035] S4.4: Maintain the set temperature and stirring state, and react for 3-8 hours. After the reaction is completed, turn off the oil bath heating device and stirring device, remove the reaction vessel from the oil bath, and let it cool naturally to room temperature. At this time, a suspension containing ternary metal sulfide precipitate is formed in the vessel.

[0036] Furthermore, S5 includes the following sub-steps:

[0037] S5.1: Transfer the suspension containing precipitate obtained in S4 to centrifuge tubes, taking care to avoid spilling the suspension. Place the centrifuge tubes into the centrifuge, ensuring that the centrifuge tubes are placed symmetrically to ensure stable operation of the centrifuge.

[0038] S5.2: Set the centrifuge speed to a specific value between 3000-8000 rpm, set the centrifugation time to the corresponding duration between 5-30 min, turn on the centrifuge, and perform centrifugation according to the set parameters;

[0039] S5.3: After centrifugation, turn off the centrifuge and wait until the centrifuge has completely stopped rotating before removing the centrifuge tube. At this time, the liquid in the tube will be separated into an upper clear liquid and a bottom precipitate. Pour off the upper clear liquid and retain the ternary metal sulfide precipitate at the bottom.

[0040] S5.4: Add deionized water or ethanol to the centrifuge tube, gently stir the precipitate with a glass rod to redisperse it, and then centrifuge again. Repeat this washing-centrifugation operation 2-5 times until the supernatant after washing is neutral and free of impurities. After the last centrifugation, retain the precipitate.

[0041] Furthermore, S6 includes the following sub-steps:

[0042] S6.1: Transfer the precipitate collected by the last centrifugation in S5 to a clean container, add an appropriate amount of deionized water, and stir with a glass rod to make the precipitate evenly dispersed in the deionized water to form a dispersion. The concentration of the dispersion should be such that it can ensure the effect of subsequent ultrasonic peeling.

[0043] S6.2: Place the container containing the dispersion into the ultrasonic instrument, set the ultrasonic power to 200-300 W and the ultrasonic time to 0.5-5 h, turn on the ultrasonic instrument, and perform ultrasonic stripping treatment. During the ultrasonic process, observe the state of the dispersion regularly to ensure that no sediment adheres to the container wall.

[0044] S6.3: After ultrasonic stripping, transfer the dispersion to a centrifuge tube and centrifuge again according to the centrifuge speed and centrifugation time parameters set in S5.

[0045] S6.4: After centrifugation, remove the centrifuge tube. The supernatant liquid in the tube at this time contains the ternary metal sulfide A with the A site missing. x In2S 3+x The solution of photocatalytic material is poured out, and the supernatant is collected for later use. If there is any precipitate at the bottom that has not been completely removed, it can be subjected to ultrasonic removal and centrifugation again.

[0046] Furthermore, the ternary metal sulfide A missing at site A x In2S 3+x The photocatalytic material has a nanosheet structure with a thickness of 4-5 nm, a lateral dimension of 0.8-1.2 μm, and a specific surface area of ​​40-45 m². 2 / g.

[0047] Furthermore, the prepared ternary metal sulfide A with A-site deletion... x In2S 3+x This photocatalytic material is used for photocatalytic sterilization and can efficiently kill Escherichia coli, Staphylococcus aureus, and drug-resistant Staphylococcus aureus in a short time.

[0048] Furthermore, the prepared ternary metal sulfide A with A-site deletion... x In2S 3+x Photocatalytic materials, which are also used for photocatalytic hydrogen production, photocatalytic degradation of organic pollutants, or preparation of solar cells.

[0049] Beneficial Effects: This invention proposes a method for improving the photocatalytic antibacterial performance of ternary metal sulfides based on an A-site deletion strategy, effectively enhancing their photocatalytic antibacterial efficiency. The deletion of A-site ions can modulate the band structure and light absorption properties of the material, while simultaneously regulating its redox capabilities of photogenerated electrons and holes, thus improving photocatalytic performance. Furthermore, the deletion of A-site ions can promote the separation of photogenerated carriers, improve their utilization rate, and promote the generation of reactive oxygen species, thereby enhancing photocatalytic antibacterial efficiency. This strategy can be applied to various ternary metal sulfides such as ZnIn2S4, MgIn2S4, and CaIn2S4. This method requires no special equipment or harsh conditions, is simple in process, highly controllable, and easily scalable, making it practical. The A-site-deleted A-site ions prepared by this method... x In2S 3+x (A = Zn, Mg, Ca, 0 < x < 1) It possesses tunable band structure, excellent visible light response, highly efficient photogenerated carrier separation capability, and superior photocatalytic sterilization performance. Among these, Zn... 0.7 In2S 3.7 It exhibits excellent photocatalytic antibacterial properties, effectively killing Escherichia coli within 10 minutes, Staphylococcus aureus within 20 minutes, and drug-resistant Staphylococcus aureus within 30 minutes. Attached Figure Description

[0050] Figure 1 The XRD patterns are those of Examples 1-5 and Comparative Example 1.

[0051] Figure 2 The XRD spectra are for Examples 6-8 and Comparative Example 2.

[0052] Figure 3 The XRD spectra are for Examples 9-11 and Comparative Example 3.

[0053] Figure 4 The UV-Vis diffuse reflectance spectra of Examples 1-5 and Comparative Example 1 are shown.

[0054] Figure 5The UV-Vis diffuse reflectance spectra of Examples 6-8 and Comparative Example 1 are shown.

[0055] Figure 6 The UV-Vis diffuse reflectance spectra of Examples 9-11 and Comparative Example 1 are shown.

[0056] Figure 7 This is a transmission electron microscope image of Example 4.

[0057] Figure 8 This is an atomic force microscope image of Example 4.

[0058] Figure 9 This is an atomic force microscope image of Example 7.

[0059] Figure 10 This is an atomic force microscope image of Example 10.

[0060] Figure 11 For Example 4 and Comparative Example 1, O2 - EPR spectrum of ·OH free radicals.

[0061] Figure 12 For Example 7 and Comparative Example 2, O2 - EPR spectrum of ·OH radicals.

[0062] Figure 13 O2 for Example 10 and Comparative Example 3 - EPR spectrum of ·OH free radicals.

[0063] Figure 14 The images show the photocatalytic killing effect of Escherichia coli in Examples 1-5 and Comparative Example 1.

[0064] Figure 15 The images show the photocatalytic killing effect of Staphylococcus aureus in Example 4 and Comparative Example 1.

[0065] Figure 16 The images show the photocatalytic killing effect of drug-resistant Staphylococcus aureus in Example 4 and Comparative Example 1.

[0066] Figure 17 The images shown are from Example 4 and are confocal fluorescence images of stained bacteria. Red represents bacterial death, and green represents bacterial survival.

[0067] Figure 18 This is a cyclical effect diagram of photocatalytic killing of Escherichia coli in Example 4.

[0068] Figure 19 The images show the photocatalytic killing effect of Escherichia coli in Example 7 and Comparative Example 2.

[0069] Figure 20 The images show the photocatalytic killing effect of Escherichia coli in Example 10 and Comparative Example 3. Detailed Implementation

[0070] It should be noted that, unless otherwise specified, the embodiments and features described in this application can be combined with each other. The application will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0071] A method for improving the photocatalytic antibacterial properties of ternary metal sulfides based on the A-site deletion strategy includes the following steps:

[0072] S1: Select an A-site metal source, an indium source, and a sulfur source. The A-site metal source is one of zinc acetate, zinc nitrate, zinc sulfate, magnesium acetate, magnesium nitrate, magnesium sulfate, calcium acetate, calcium nitrate, or calcium sulfate. The indium source is indium nitrate or indium chloride. The sulfur source is thioacetamide or cysteine. The molar ratio of A-site metal ion to indium ion is x : 2 (0 < x < 1), corresponding to A... x In2S 3+x The ratio of the total valence states of sulfide ions to A-site metal ions and indium ions was determined by weighing each raw material.

[0073] S2: Add the weighed A-site metal source and indium source to deionized water, stir at room temperature for 30 min to fully dissolve and mix the A-site metal source and indium source to form a mixed solution.

[0074] S3: Add the weighed sulfur source to the mixed solution obtained in S2, and continue stirring until the sulfur source is completely dissolved to obtain the reaction precursor solution;

[0075] S4: Transfer the reaction precursor liquid obtained in S3 to an oil bath, control the oil bath temperature at 80-120 ℃, and stir vigorously at the same time. Maintain this temperature and stirring state for 3-8 h to generate a suspension containing ternary metal sulfide precipitate.

[0076] S5: Centrifuge the suspension obtained in S4. Set the centrifuge speed to 3000-8000 rpm and the centrifugation time to 5-30 min. Collect the precipitate at the bottom after centrifugation. Wash the precipitate 2-5 times with deionized water or ethanol. Then redisperse the washed precipitate in deionized water to form a dispersion.

[0077] S6: The dispersion obtained in S5 was subjected to ultrasonic exfoliation. The ultrasonic power was set to 200-300 W and the ultrasonic time was 0.5-5 h. After ultrasonication, it was centrifuged again with the same centrifugation parameters as in S5. The supernatant was taken, which is the ternary metal sulfide A missing at site A. x In2S 3+x Photocatalytic materials.

[0078] Preferably, S1 includes the following sub-steps:

[0079] S1.1: Determine the target product A x In2S 3+x For the type of A, if A is Zn, then one of zinc acetate, zinc nitrate, and zinc sulfate is selected as the metal source at the A site; if A is Mg, then one of magnesium acetate, magnesium nitrate, and magnesium sulfate is selected as the metal source at the A site; if A is Ca, then one of calcium acetate, calcium nitrate, and calcium sulfate is selected as the metal source at the A site.

[0080] S1.2: Based on the target x value, 0 < x < 1, calculate the molar amounts of the metal source and indium source at site A to ensure that the molar ratio of metal ions to indium ions at site A is accurate to x : 2, wherein the indium source is selected from either indium nitrate or indium chloride.

[0081] S1.3: Based on the total molar number of metal ions and indium ions at site A, calculate the amount of sulfur source to be used, such that the molar number of sulfur ions and the total molar number of metal ions and indium ions at site A satisfy A. x In2S 3+x The stoichiometric ratio, the sulfur source is selected from either thioacetamide or cysteine;

[0082] S1.4: Using a weighing instrument with the required accuracy, weigh the calculated amounts of the metal source at position A, the indium source, and the sulfur source, and place each raw material in a clean container for later use.

[0083] Preferably, S2 includes the following sub-steps:

[0084] S2.1: Select a clean reaction vessel and add a set volume of deionized water to it. The volume of deionized water should meet the requirements for subsequent raw material dissolution and reaction, which is 250 mL.

[0085] S2.2: Slowly add the metal source at site A weighed in S1 into the reaction vessel containing deionized water, turn on the stirring device, and set the stirring speed to a value that can fully dissolve the raw materials without producing too much foam. Observe the dissolution of the metal source at site A during the stirring process until it is completely dissolved.

[0086] S2.3: After the metal source at site A has completely dissolved, slowly add the indium source weighed in S1 into the solution in the reaction vessel, keep the stirring device running continuously, avoid splashing the solution during the stirring process, and ensure that the indium source is evenly dispersed in the solution;

[0087] S2.4: Stir continuously for 30 min, and observe the solution state regularly during this period to ensure that the metal source at site A and the indium source are completely dissolved, and that the solution is uniformly mixed without obvious particles or stratification, forming a homogeneous mixed solution.

[0088] Preferably, S3 includes the following sub-steps:

[0089] S3.1: Keep the stirring device running in S2, and slowly add the sulfur source weighed in S1 to the mixed solution obtained in S2. Control the addition rate of the sulfur source during the addition process to avoid precipitation caused by excessively high local concentration due to excessive addition.

[0090] S3.2: After the sulfur source is completely added, continue stirring at the same speed as in S2 to ensure that the sulfur source is evenly dispersed in the mixed solution. At the same time, observe whether there are any abnormal phenomena in the solution, such as sudden color change or the formation of flocculent matter.

[0091] S3.3: Continue stirring for a period of time until the sulfur source is completely dissolved. Observe with the naked eye whether the solution is transparent and free of solid particles. If there are still undissolved sulfur source particles, the stirring rate can be increased or the stirring time can be extended appropriately.

[0092] S3.4: After the sulfur source is completely dissolved, the reaction precursor solution is obtained. Stop stirring and let the reaction precursor solution stand for a while to observe whether a precipitate is formed. If a precipitate is formed, it needs to be stirred again until the precipitate is dissolved to ensure that the reaction precursor solution is uniform and stable.

[0093] Preferably, S4 includes the following sub-steps:

[0094] S4.1: Set the temperature of the oil bath to a specific value between 80-120 ℃, turn on the oil bath heating device, and after the oil bath temperature stabilizes at the set value, put the reaction vessel containing the reaction precursor liquid obtained in S3 into the oil bath, ensuring that the bottom of the reaction vessel is completely submerged in the oil bath.

[0095] S4.2: Turn on the stirring device and adjust the stirring speed to a vigorous stirring state to ensure that the reaction precursor solution is fully mixed during the reaction process to avoid uneven local reaction. At the same time, record the reaction start time.

[0096] S4.3: During the reaction, regularly observe the state of the solution in the reaction vessel, including color changes, whether precipitation is formed and the amount of precipitation. At the same time, monitor the temperature of the oil bath to ensure that the temperature is stable at the set value. If the temperature fluctuates, adjust the oil bath parameters in time.

[0097] S4.4: Maintain the set temperature and stirring state, and react for 3-8 hours. After the reaction is completed, turn off the oil bath heating device and stirring device, remove the reaction vessel from the oil bath, and let it cool naturally to room temperature. At this time, a suspension containing ternary metal sulfide precipitate is formed in the vessel.

[0098] Preferably, S5 includes the following sub-steps:

[0099] S5.1: Transfer the suspension containing precipitate obtained in S4 to centrifuge tubes, taking care to avoid spilling the suspension. Place the centrifuge tubes into the centrifuge, ensuring that the centrifuge tubes are placed symmetrically to ensure stable operation of the centrifuge.

[0100] S5.2: Set the centrifuge speed to a specific value between 3000-8000 rpm, set the centrifugation time to the corresponding duration between 5-30 min, turn on the centrifuge, and perform centrifugation according to the set parameters;

[0101] S5.3: After centrifugation, turn off the centrifuge and wait until the centrifuge has completely stopped rotating before removing the centrifuge tube. At this time, the liquid in the tube will be separated into an upper clear liquid and a bottom precipitate. Pour off the upper clear liquid and retain the ternary metal sulfide precipitate at the bottom.

[0102] S5.4: Add deionized water or ethanol to the centrifuge tube, gently stir the precipitate with a glass rod to redisperse it, and then centrifuge again. Repeat this washing-centrifugation operation 2-5 times until the supernatant after washing is neutral and free of impurities. After the last centrifugation, retain the precipitate.

[0103] Preferably, S6 includes the following sub-steps:

[0104] S6.1: Transfer the precipitate collected by the last centrifugation in S5 to a clean container, add an appropriate amount of deionized water, and stir with a glass rod to make the precipitate evenly dispersed in the deionized water to form a dispersion. The concentration of the dispersion should be such that it can ensure the effect of subsequent ultrasonic peeling.

[0105] S6.2: Place the container containing the dispersion into the ultrasonic instrument, set the ultrasonic power to 200-300 W and the ultrasonic time to 0.5-5 h, turn on the ultrasonic instrument, and perform ultrasonic stripping treatment. During the ultrasonic process, observe the state of the dispersion regularly to ensure that no sediment adheres to the container wall.

[0106] S6.3: After ultrasonic stripping, transfer the dispersion to a centrifuge tube and centrifuge again according to the centrifuge speed and centrifugation time parameters set in S5.

[0107] S6.4: After centrifugation, remove the centrifuge tube. The supernatant liquid in the tube at this time contains the ternary metal sulfide A with the A site missing. x In2S 3+x The solution of photocatalytic material is poured out, and the supernatant is collected for later use. If there is any precipitate at the bottom that has not been completely removed, it can be subjected to ultrasonic removal and centrifugation again.

[0108] Preferably, the ternary metal sulfide A missing at position A... x In2S 3+xThe photocatalytic material has a nanosheet structure with a thickness of 4-5 nm, a lateral dimension of 0.8-1.2 μm, and a specific surface area of ​​40-45 m². 2 / g.

[0109] Preferably, the prepared ternary metal sulfide A with A-site deletion x In2S 3+x Photocatalytic material, used for photocatalytic sterilization, effectively kills Escherichia coli, Staphylococcus aureus, and drug-resistant Staphylococcus aureus within a preset time.

[0110] Preferably, the prepared ternary metal sulfide A with A-site deletion x In2S 3+x Photocatalytic materials, which are also used for photocatalytic hydrogen production, photocatalytic degradation of organic pollutants, or preparation of solar cells.

[0111] Example 1: The present invention's ultra-thin A x In2S 3+x Preparation of Nanosheets (A = Zn, x = 0.2) (Part 1)

[0112] 0.2 mmol zinc acetate and 2 mmol anhydrous indium chloride were dissolved in 250 mL deionized water. After stirring at room temperature for 30 min, 3.2 mmol thioacetamide was added, and the mixture was placed in an oil bath and heated to 95 °C, and stirred vigorously for 5 h. The resulting suspension was centrifuged, the precipitate was collected and washed twice with deionized water, and then dispersed again in 200 mL deionized water. The mixture was sonicated at 40 kHz and 250 W for 30 min, and then centrifuged at 6000 rpm for 5 min. The supernatant was taken as the final product.

[0113] Example 2: The present invention's ultrathin A x In2S 3+x Preparation of Nanosheets (A = Zn, x = 0.4) (Part 2)

[0114] 0.4 mmol zinc acetate and 2 mmol anhydrous indium chloride were dissolved in 250 mL deionized water. After stirring at room temperature for 30 min, 3.4 mmol thioacetamide was added, and the mixture was placed in an oil bath and heated to 95 °C, and stirred vigorously for 5 h. The resulting suspension was centrifuged, the precipitate was collected and washed twice with deionized water, and then dispersed again in 200 mL deionized water. The mixture was sonicated at 40 kHz and 250 W for 30 min, and then centrifuged at 6000 rpm for 5 min. The supernatant was taken as the final product.

[0115] Example 3: The present invention's ultrathin A x In2S 3+xPreparation of Nanosheets (A = Zn, x = 0.6) (Part 3)

[0116] 0.6 mmol zinc acetate and 2 mmol anhydrous indium chloride were dissolved in 250 mL deionized water. After stirring at room temperature for 30 min, 3.6 mmol thioacetamide was added, and the mixture was placed in an oil bath and heated to 95 °C, and stirred vigorously for 5 h. The resulting suspension was centrifuged, the precipitate was collected and washed twice with deionized water, and then dispersed again in 200 mL deionized water. The mixture was sonicated at 40 kHz and 250 W for 30 min, and then centrifuged at 6000 rpm for 5 min. The supernatant was taken as the final product.

[0117] Example 4: The present invention's ultrathin A x In2S 3+x Preparation of Nanosheets (A = Zn, x = 0.7) (Part 4)

[0118] 0.7 mmol zinc acetate and 2 mmol anhydrous indium chloride were dissolved in 250 mL deionized water. After stirring at room temperature for 30 min, 3.7 mmol thioacetamide was added, and the mixture was then placed in an oil bath and heated to 95 °C, and stirred vigorously for 5 h. The resulting suspension was centrifuged, the precipitate was collected and washed twice with deionized water, and then dispersed again in 200 mL deionized water. The mixture was sonicated at 40 kHz and 250 W for 30 min, and then centrifuged at 6000 rpm for 5 min. The supernatant was taken as the final product.

[0119] Example 5: The present invention's ultrathin A x In2S 3+x Preparation of Nanosheets (A = Zn, x = 0.8) (Part 5)

[0120] 0.8 mmol zinc acetate and 2 mmol anhydrous indium chloride were dissolved in 250 mL deionized water and stirred at room temperature for 30 min. Then, 3.8 mmol thioacetamide was added, and the mixture was placed in an oil bath and heated to 95 °C, and stirred vigorously for 5 h. The resulting suspension was centrifuged, the precipitate was collected and washed twice with deionized water, and then dispersed again in 200 mL deionized water. The mixture was sonicated at 40 kHz and 250 W for 30 min, and then centrifuged at 6000 rpm for 5 min. The supernatant was taken as the final product.

[0121] Example 6: The present invention's ultrathin A x In2S 3+x Preparation of Nanosheets (A = Mg, x = 0.5) (Part 6)

[0122] 0.5 mmol magnesium acetate and 2 mmol anhydrous indium chloride were dissolved in 250 mL deionized water and stirred at room temperature for 30 min. Then, 3.5 mmol thioacetamide was added, and the mixture was placed in an oil bath and heated to 95 °C, and stirred vigorously for 5 h. The resulting suspension was centrifuged, the precipitate was collected and washed twice with deionized water, and then dispersed again in 200 mL deionized water. The mixture was sonicated at 40 kHz and 250 W for 30 min, and then centrifuged at 6000 rpm for 5 min. The supernatant was taken as the final product.

[0123] Example 7: The ultra-thin A of the present invention x In2S 3+x Preparation of Nanosheets (A = Mg, x = 0.7) (Part 7)

[0124] 0.7 mmol magnesium acetate and 2 mmol anhydrous indium chloride were dissolved in 250 mL deionized water. After stirring at room temperature for 30 min, 3.7 mmol thioacetamide was added, and the mixture was placed in an oil bath and heated to 95 °C, and stirred vigorously for 5 h. The resulting suspension was centrifuged, the precipitate was collected and washed twice with deionized water, and then dispersed again in 200 mL deionized water. The mixture was sonicated at 40 kHz and 250 W for 30 min, and then centrifuged at 6000 rpm for 5 min. The supernatant was taken as the final product.

[0125] Example 8: The present invention's ultrathin A x In2S 3+x Preparation of Nanosheets (A = Mg, x = 0.9) (Part 8)

[0126] 0.9 mmol magnesium acetate and 2 mmol anhydrous indium chloride were dissolved in 250 mL deionized water and stirred at room temperature for 30 min. Then, 3.9 mmol thioacetamide was added, and the mixture was placed in an oil bath and heated to 95 °C, and stirred vigorously for 5 h. The resulting suspension was centrifuged, the precipitate was collected and washed twice with deionized water, and then dispersed again in 200 mL deionized water. The mixture was sonicated at 40 kHz and 250 W for 30 min, and then centrifuged at 6000 rpm for 5 min. The supernatant was taken as the final product.

[0127] Example 9: The present invention's ultrathin A x In2S 3+x Preparation of Nanosheets (A = Ca, x = 0.5) (Part 9)

[0128] 0.5 mmol calcium acetate and 2 mmol anhydrous indium chloride were dissolved in 250 mL deionized water. After stirring at room temperature for 30 min, 3.5 mmol thioacetamide was added, and the mixture was placed in an oil bath and heated to 95 °C, and stirred vigorously for 5 h. The resulting suspension was centrifuged, the precipitate was collected and washed twice with deionized water, and then dispersed again in 200 mL deionized water. The mixture was sonicated at 40 kHz and 250 W for 30 min, and then centrifuged at 6000 rpm for 5 min. The supernatant was taken as the final product.

[0129] Example 10: The present invention's ultrathin A x In2S 3+x Preparation of Nanosheets (A = Ca, x = 0.7) (Part 10)

[0130] 0.7 mmol calcium acetate and 2 mmol anhydrous indium chloride were dissolved in 250 mL deionized water. After stirring at room temperature for 30 min, 3.7 mmol thioacetamide was added, and the mixture was placed in an oil bath and heated to 95 °C, and stirred vigorously for 5 h. The resulting suspension was centrifuged, the precipitate was collected and washed three times with deionized water, and then dispersed again in 200 mL deionized water. The mixture was sonicated at 40 kHz and 250 W for 30 min, and then centrifuged at 6000 rpm for 5 min. The supernatant was taken as the final product.

[0131] Example 11 The present invention ultrathin A x In2S 3+x Preparation of Nanosheets (A = Ca, x = 0.9) (XI)

[0132] 0.9 mmol calcium acetate and 2 mmol anhydrous indium chloride were dissolved in 250 mL deionized water and stirred at room temperature for 30 min. Then, 3.9 mmol thioacetamide was added, and the mixture was placed in an oil bath and heated to 95 °C, and stirred vigorously for 5 h. The resulting suspension was centrifuged, the precipitate was collected and washed three times with deionized water, and then dispersed again in 200 mL deionized water. The mixture was sonicated at 40 kHz and 250 W for 30 min, and then centrifuged at 6000 rpm for 5 min. The supernatant was taken as the final product.

[0133] Comparative Example 1

[0134] To highlight the superior performance of the A-site metal-deficient photocatalyst provided in this invention, a ternary metal sulfide without A-site cation regulation was synthesized as a comparison.

[0135] 1 mmol zinc acetate and 2 mmol anhydrous indium chloride were dissolved in 250 mL deionized water. After stirring at room temperature for 30 min, 4 mmol thioacetamide was added, and the mixture was placed in an oil bath and heated to 120 °C with vigorous stirring for 5 h. The resulting suspension was centrifuged, the precipitate was collected and washed three times with deionized water, and then dispersed again in 200 mL deionized water. The mixture was sonicated at 40 kHz and 150 W for 30 min, and then centrifuged at 3000 rpm for 15 min. The supernatant was taken as the final product ZnIn2S4.

[0136] Comparative Example 2

[0137] The reaction steps were the same as in Comparative Example 1, except that zinc acetate was replaced with magnesium acetate to prepare the MgIn2S4 photocatalyst.

[0138] Comparative Example 3

[0139] The reaction steps were the same as in Comparative Example 1, except that zinc acetate was replaced with calcium acetate to prepare CaIn2S4 photocatalyst.

[0140] Example 12 Structural Characterization

[0141] The crystal structure of the sample was characterized using X-ray powder diffraction, such as... Figure 1-3 As shown, all samples with Zn at the A site are hexagonal, while those with Mg and Ca at the A site are cubic. The absence of metal elements at the A site did not change the crystal structure of the material.

[0142] Example 13 Characterization of light absorption performance

[0143] The light absorption properties of the material were characterized using ultraviolet-visible diffuse reflectance spectra, such as... Figure 4-6 As shown, as x decreases, the absorption edge of the material redshifts, the band gap narrows, and the light absorption performance is enhanced. However, this also weakens the redox ability of photogenerated holes and electrons. Therefore, adjusting the content of metal elements at the A site can effectively find the balance between the redox ability of photogenerated carriers and the light absorption performance, thereby achieving better photocatalytic sterilization performance.

[0144] Example 14 Morphological Observation

[0145] The morphology of the product was observed using a JEMF200 high-resolution transmission electron microscope. The transmission electron microscope image of Example 4 is shown below. Figure 7 As shown, the morphology of the nanosheets is revealed. Calculations using AFM atomic probe microscopy show that... Figure 8-10 As shown, the nanosheets in Examples 4, 8, and 10 have a thickness of 4-5 nm, which is A. x In2S 3+xBilayer nanosheets with a lateral dimension of 1 µm and a specific surface area of ​​approximately 40-45 m² 2 / g.

[0146] Example 15 Elemental Content Test

[0147] The elemental content in the material was tested by ICP-OES, and the results are shown in Table 1. The elemental content was basically consistent with the feed ratio, proving the successful preparation of the A-site-deficient ternary metal sulfide.

[0148] Table 1. Metal element content of Examples 1-12 and Comparative Examples 1-3

[0149] Zn content (wt%) Mg content (wt%) Ca content (wt%) In content (wt%) Example 1 4.25 - - 61.64 Example 2 7.66 - - 59.64 Example 3 10.37 - - 57.02 Example 4 11.61 - - 56.86 Example 5 13.39 - - 54.66 Comparative Example 1 15.29 - - 52.08 Example 6 - 3.42 - 64.27 Example 7 - 4.86 - 63.01 Example 8 - 5.73 - 61.42 Comparative Example 2 - 6.42 - 60.13 Example 9 - - 5.21 63.22 Example 10 - - 7.23 61.07 Example 11 - - 9.35 58.92 Comparative Example 3 - - 10.21 57.80

[0150] Example 16 Characterization of free radical generation

[0151] The free radicals generated in the samples were characterized using a Bruker ESR 5000 electron paramagnetic resonance spectrometer, with DMPO used as a scavenger for superoxide and hydroxyl radicals. See [link to relevant documentation]. Figure 11-13 When x = 0.7, the signals of superoxide radicals and hydroxyl radicals generated are significantly stronger than those of materials without A-site deletion, indicating that A-site deletion effectively improves the photogenerated carrier separation capability of the material and promotes the generation of reactive oxygen species.

[0152] Example 17: Photocatalytic bactericidal performance test

[0153] The photocatalytic bactericidal performance of the obtained nanosheets was tested: 23.3 mL of a 1 mg / mL sample and 1.7 mL of a 0.5 McFarland unit suspension of *E. coli* were mixed and stirred thoroughly. The mixture was stirred in the dark for 30 min, then irradiated with a 300 W xenon lamp equipped with a 400 nm filter. 100 µL of the solution was extracted from the dark at 0 min, 30 min, and different lighting times, and diluted 1000 times. Then, 100 µL of the diluted mixture was mixed with 300 µL of physiological saline and spread onto sheep blood agar plates. After incubation overnight, the plates were observed and counted.

[0154] The nanosheets obtained above were subjected to photocatalytic killing of Staphylococcus aureus. Except for replacing Escherichia coli in the bacterial solution with Staphylococcus aureus, the other steps were the same as the test steps for Escherichia coli.

[0155] The nanosheets obtained above were subjected to photocatalytic killing of drug-resistant Staphylococcus aureus. Except for replacing Escherichia coli in the bacterial solution with drug-resistant Staphylococcus aureus, the other steps were the same as the test steps for Escherichia coli.

[0156] Depend on Figure 14It can be seen that when position A is Zn, Zn 0.7 In2S 3.7 It exhibited optimal bactericidal performance, effectively killing E. coli within 10 minutes. Similarly, Zn 0.7 In2S 3.7 It also exhibited excellent bactericidal properties against Staphylococcus aureus and drug-resistant Staphylococcus aureus. For example... Figure 15-17 As shown, Zn 0.7 In2S 3.7 It can effectively kill Staphylococcus aureus within 20 minutes and drug-resistant Staphylococcus aureus within 30 minutes, significantly outperforming ZnIn2S4. Furthermore, this material also exhibits good stability, stably and efficiently killing Escherichia coli within 5 cycles. Figure 18 As shown. Additionally, Mg prepared according to the method of the present invention... 0.7 In2S 3.7 and Ca 0.7 In2S 3.7 It also exhibited superior photocatalytic bactericidal performance compared to unmodified MgIn2S4 and CaIn2S4, such as... Figures 19-20 As shown in Table 2, the photocatalytic bactericidal performance test results of other examples and comparative examples are shown in Table 2. Compared with the unmodified ternary metal sulfide, the A-site missing A... x In2S 3+x (A=Zn, Mg, Ca, 0 < x < 1) Photocatalysts have higher sterilization efficiency. The photoactivity of the catalyst comes from its suitable band structure, superior visible light response capability, and efficient photogenerated carrier separation and transport capability.

[0157] Table 2. Percentage of viable bacteria (%) in the products of Examples 1-11 and Comparative Examples 1-3 at 10 min time points.

[0158] Group E. coli Staphylococcus aureus Drug-resistant Staphylococcus aureus Example 1 0.2 25.7 39.0 Example 2 0.4 23.6 35.2 Example 3 0 19.5 30.2 Example 4 0 17.3 28.1 Example 5 2.6 22.9 32.8 Example 6 16.2 55.7 53.2 Example 7 13.7 50.2 58.9 Example 8 17.1 53.2 59.3 Example 9 27.7 60.1 67.9 Example 10 21.3 55.9 59.3 Example 11 23.4 58.6 65.4 Comparative Example 1 0.8 49.0 50.1 Comparative Example 2 50.2 68.8 76.3 Comparative Example 3 62.7 73.2 80.2

[0159] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various equivalent changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A method for improving the photocatalytic antibacterial properties of ternary metal sulfides based on an A-site deletion strategy, characterized in that, Includes the following steps: S1: Select a metal source at the A-site, an indium source, and a sulfur source. The metal source at the A-site is one of zinc acetate, zinc nitrate, zinc sulfate, magnesium acetate, magnesium nitrate, magnesium sulfate, calcium acetate, calcium nitrate, or calcium sulfate. The indium source is indium nitrate or indium chloride. The sulfur source is thioacetamide or cysteine. According to the molar ratio of metal ions at the A-site to indium ions of x:2, where 0 < x < 1, corresponding to A x In2S 3+x , and the sulfur ions are in a proportion adapted to the valence states of the metal ions at the A-site and indium ions, and weigh the raw materials; S2: Add the weighed A-site metal source and indium source to deionized water, stir at room temperature for 30 min to fully dissolve and mix the A-site metal source and indium source to form a mixed solution. S3: Add the weighed sulfur source to the mixed solution obtained in S2, and continue stirring until the sulfur source is completely dissolved to obtain the reaction precursor solution; S4: Transfer the reaction precursor liquid obtained in S3 to an oil bath, control the oil bath temperature at 80-120 ℃, and stir vigorously at the same time. Maintain this temperature and stirring state for 3-8 h to generate a suspension containing ternary metal sulfide precipitate. S5: Centrifuge the suspension obtained in S4. Set the centrifuge speed to 3000-8000 rpm and the centrifugation time to 5-30 min. Collect the precipitate at the bottom after centrifugation. Wash the precipitate 2-5 times with deionized water or ethanol. Then redisperse the washed precipitate in deionized water to form a dispersion. S6: The dispersion obtained in S5 was subjected to ultrasonic exfoliation. The ultrasonic power was set to 200-300 W and the ultrasonic time was 0.5-5 h. After ultrasonication, it was centrifuged again with the same centrifugation parameters as in S5. The supernatant was taken, which is the ternary metal sulfide A missing at site A. x In2S 3+x Photocatalytic materials.

2. The method for improving the photocatalytic antibacterial performance of ternary metal sulfides based on the A-site deletion strategy according to claim 1, characterized in that, S1 includes the following steps: S1.1: Determine the target product A x In2S 3+x For the type of A, if A is Zn, then one of zinc acetate, zinc nitrate, and zinc sulfate is selected as the metal source at the A site; if A is Mg, then one of magnesium acetate, magnesium nitrate, and magnesium sulfate is selected as the metal source at the A site; if A is Ca, then one of calcium acetate, calcium nitrate, and calcium sulfate is selected as the metal source at the A site. S1.2: Based on the target x value, 0 < x < 1, calculate the molar amounts of the metal source and indium source at site A to ensure that the molar ratio of metal ions to indium ions at site A is accurate to x : 2, wherein the indium source is selected from either indium nitrate or indium chloride. S1.3: Based on the total molar number of metal ions and indium ions at site A, calculate the amount of sulfur source to be used, such that the molar number of sulfur ions and the total molar number of metal ions and indium ions at site A satisfy A. x In2S 3+x The stoichiometric ratio, the sulfur source is selected from either thioacetamide or cysteine; S1.4: Using a weighing instrument with the required accuracy, weigh the calculated amounts of the metal source at position A, the indium source, and the sulfur source, and place each raw material in a clean container for later use.

3. The method for improving the photocatalytic antibacterial performance of ternary metal sulfides based on the A-site deletion strategy according to claim 1, characterized in that, S2 includes the following steps: S2.1: Select a clean reaction vessel and add a set volume of deionized water to it. The volume of deionized water should meet the requirements for subsequent raw material dissolution and reaction, which is 250 mL. S2.2: Slowly add the metal source at site A weighed in S1 into the reaction vessel containing deionized water, turn on the stirring device, and set the stirring speed to a value that can fully dissolve the raw materials without producing too much foam. Observe the dissolution of the metal source at site A during the stirring process until it is completely dissolved. S2.3: After the metal source at site A has completely dissolved, slowly add the indium source weighed in S1 into the solution in the reaction vessel, keep the stirring device running continuously, avoid splashing the solution during the stirring process, and ensure that the indium source is evenly dispersed in the solution; S2.4: Stir continuously for 30 min, and observe the solution state regularly during this period to ensure that the metal source at site A and the indium source are completely dissolved, and that the solution is uniformly mixed without obvious particles or stratification, forming a homogeneous mixed solution.

4. The method for improving the photocatalytic antibacterial performance of ternary metal sulfides based on the A-site deletion strategy according to claim 1, characterized in that, S3 includes the following steps: S3.1: Keep the stirring device running in S2, and slowly add the sulfur source weighed in S1 to the mixed solution obtained in S2. Control the addition rate of the sulfur source during the addition process to avoid precipitation caused by excessively high local concentration due to excessive addition. S3.2: After the sulfur source is completely added, continue stirring at the same speed as in S2 to ensure that the sulfur source is evenly dispersed in the mixed solution. At the same time, observe whether there are any abnormal phenomena in the solution, such as sudden color change or the formation of flocculent matter. S3.3: Continue stirring for a period of time until the sulfur source is completely dissolved. Observe with the naked eye whether the solution is transparent and free of solid particles. If there are still undissolved sulfur source particles, the stirring rate can be increased or the stirring time can be extended appropriately. S3.4: After the sulfur source is completely dissolved, the reaction precursor solution is obtained. Stop stirring and let the reaction precursor solution stand for a while to observe whether a precipitate is formed. If a precipitate is formed, it needs to be stirred again until the precipitate is dissolved to ensure that the reaction precursor solution is uniform and stable.

5. The method for improving the photocatalytic antibacterial performance of ternary metal sulfides based on the A-site deletion strategy according to claim 1, characterized in that, S4 includes the following steps: S4.1: Set the temperature of the oil bath to a specific value between 80-120 ℃, turn on the oil bath heating device, and after the oil bath temperature stabilizes at the set value, put the reaction vessel containing the reaction precursor liquid obtained in S3 into the oil bath, ensuring that the bottom of the reaction vessel is completely submerged in the oil bath. S4.2: Turn on the stirring device and adjust the stirring speed to a vigorous stirring state to ensure that the reaction precursor solution is fully mixed during the reaction process to avoid uneven local reaction. At the same time, record the reaction start time. S4.3: During the reaction, regularly observe the state of the solution in the reaction vessel, including color changes, whether precipitation is formed and the amount of precipitation. At the same time, monitor the temperature of the oil bath to ensure that the temperature is stable at the set value. If the temperature fluctuates, adjust the oil bath parameters in time. S4.4: Maintain the set temperature and stirring state, and react for 3-8 hours. After the reaction is completed, turn off the oil bath heating device and stirring device, remove the reaction vessel from the oil bath, and let it cool naturally to room temperature. At this time, a suspension containing ternary metal sulfide precipitate is formed in the vessel.

6. The method for improving the photocatalytic antibacterial performance of ternary metal sulfides based on the A-site deletion strategy according to claim 1, characterized in that, S5 includes the following steps: S5.1: Transfer the suspension containing precipitate obtained in S4 to centrifuge tubes, taking care to avoid spilling the suspension. Place the centrifuge tubes into the centrifuge, ensuring that the centrifuge tubes are placed symmetrically to ensure stable operation of the centrifuge. S5.2: Set the centrifuge speed to a specific value between 3000-8000 rpm, set the centrifugation time to the corresponding duration between 5-30 min, turn on the centrifuge, and perform centrifugation according to the set parameters; S5.3: After centrifugation, turn off the centrifuge and wait until the centrifuge has completely stopped rotating before removing the centrifuge tube. At this time, the liquid in the tube will be separated into an upper clear liquid and a bottom precipitate. Pour off the upper clear liquid and retain the ternary metal sulfide precipitate at the bottom. S5.4: Add deionized water or ethanol to the centrifuge tube, gently stir the precipitate with a glass rod to redisperse it, and then centrifuge again. Repeat this washing-centrifugation operation 2-5 times until the supernatant after washing is neutral and free of impurities. After the last centrifugation, retain the precipitate.

7. The method for improving the photocatalytic antibacterial performance of ternary metal sulfides based on the A-site deletion strategy according to claim 1, characterized in that, S6 includes the following steps: S6.1: Transfer the precipitate collected by the last centrifugation in S5 to a clean container, add an appropriate amount of deionized water, and stir with a glass rod to make the precipitate evenly dispersed in the deionized water to form a dispersion. The concentration of the dispersion should be such that it can ensure the effect of subsequent ultrasonic peeling. S6.2: Place the container containing the dispersion into the ultrasonic instrument, set the ultrasonic power to 200-300 W and the ultrasonic time to 0.5-5 h, turn on the ultrasonic instrument, and perform ultrasonic stripping treatment. During the ultrasonic process, observe the state of the dispersion regularly to ensure that no sediment adheres to the container wall. S6.3: After ultrasonic stripping, transfer the dispersion to a centrifuge tube and centrifuge again according to the centrifuge speed and centrifugation time parameters set in S5. S6.4: After centrifugation, remove the centrifuge tube. The supernatant liquid in the tube at this time contains the ternary metal sulfide A with the A site missing. x In2S 3+x The solution of photocatalytic material is poured out, and the supernatant is collected for later use. If there is any precipitate at the bottom that has not been completely removed, it can be subjected to ultrasonic removal and centrifugation again.

8. The method for improving the photocatalytic antibacterial performance of ternary metal sulfides based on an A-site deletion strategy according to any one of claims 1-7, characterized in that, The ternary metal sulfide A with the A site missing x In2S 3+x The photocatalytic material has a nanosheet structure with a thickness of 4-5 nm, a lateral dimension of 0.8-1.2 μm, and a specific surface area of ​​40-45 m². 2 / g.

9. The method for improving the photocatalytic antibacterial performance of ternary metal sulfides based on an A-site deletion strategy according to any one of claims 1-7, characterized in that, Prepared A-site-deficient ternary metal sulfide A x In2S 3+x Photocatalytic material, used for photocatalytic sterilization, effectively kills Escherichia coli, Staphylococcus aureus, and drug-resistant Staphylococcus aureus within a preset time.

10. The method for improving the photocatalytic antibacterial performance of ternary metal sulfides based on an A-site deletion strategy according to any one of claims 1-7, characterized in that, Prepared A-site-deficient ternary metal sulfide A x In2S 3+x Photocatalytic materials, which are also used for photocatalytic hydrogen production, photocatalytic degradation of organic pollutants, or preparation of solar cells.

Images