Negative ion release type activated carbon composite purification material and preparation method thereof

Abstract

The invention provides a negative ion release type activated carbon composite purification material and a preparation method thereof, and belongs to the technical field of activated carbon composite purification materials. The invention constructs an efficient composite purification material. Firstly, a porous nitrogen-doped modified aerogel substrate is responsible for efficiently adsorbing pollutants and serves as a firm loading platform; then, near-infrared light in the environment is converted into high-energy ultraviolet / blue light by the up-conversion nanoparticles, and the high-energy ultraviolet / blue light is used as an internal light source to excite the piezoelectric heterojunction to generate photo-generated charges. Under the airflow disturbance, the piezoelectric effect in the heterojunction can generate a strong electric field, and the electric field improves the separation efficiency of photo-generated charges; finally, oxygen is reduced into electronegative active species such as superoxide silver ions by the efficiently separated electrons, and adsorbed pollutants are degraded in cooperation with other active species. And efficient cooperative utilization of low-quality light energy and mechanical energy in the environment is realized.

Description

Technical Field

[0001] This invention belongs to the technical field of activated carbon composite purification materials, and relates to a negative ion releasing activated carbon composite purification material and its preparation method. Background Technology

[0002] With increasing societal demands for health and environmental quality, the development of efficient and long-lasting air purification technologies has become a research hotspot. Activated carbon, due to its large specific surface area and well-developed pore structure, excels in the physical adsorption of volatile organic compounds (VOCs) and particulate matter, making it one of the most widely used purification materials. However, the adsorption of pure activated carbon is a reversible physical process with limited adsorption capacity; once saturated, it easily becomes ineffective and may cause secondary pollution. To overcome this drawback, combining semiconductor photocatalysts with activated carbon, utilizing the strong oxidizing free radicals generated by photocatalysis to degrade the adsorbed pollutants in situ, is considered an effective way to achieve "self-regeneration" of activated carbon and enhance the purification depth.

[0003] Despite some progress in combining semiconductor photocatalysts with activated carbon, existing technologies still face two major challenges that limit their practical application performance: First, traditional composite materials primarily rely on ambient light (especially ultraviolet light) to excite the semiconductor. However, the rapid recombination of photogenerated electron-hole pairs is an inherent challenge in semiconductor photocatalysis, resulting in a significant waste of light energy and low catalytic quantum efficiency. Even with the construction of heterojunctions, this passive charge separation method offers limited improvement and struggles to maintain efficient pollutant degradation rates in complex real-world environments. Second, the catalytic activity of existing composite materials is entirely dependent on light intensity. Indoors, at night, or under low-light conditions, due to insufficient light energy input, their catalytic function almost completely ceases, and the material degenerates into a simple physical adsorbent. This severely limits their potential as an all-weather, long-lasting purification material. Summary of the Invention

[0004] To address the aforementioned problems, the present invention aims to provide a negative ion-releasing activated carbon composite purification material and its preparation method. This application constructs a highly efficient purification material by loading core-shell upconversion nanoparticles and bismuth oxyiodide / bismuth ferrite heterojunctions onto a nitrogen-doped graphene / activated carbon aerogel substrate. First, the porous, nitrogen-doped aerogel substrate is responsible for efficiently adsorbing pollutants and serves as a robust loading platform. Subsequently, the upconversion nanoparticles convert near-infrared light from the environment into high-energy ultraviolet / blue light, which serves as an internal light source to excite the piezoelectric heterojunction to generate photogenerated charges. Under airflow disturbance, the piezoelectric effect in the heterojunction generates a strong electric field, which improves the separation efficiency of the photogenerated charges. Finally, the efficiently separated electrons reduce oxygen to negatively charged reactive species such as superoxide anions, which synergistically degrade the adsorbed pollutants with other reactive species. This achieves the efficient synergistic utilization of low-quality light and mechanical energy in the environment.

[0005] To achieve this objective, the present invention adopts the following technical solution:

[0006] In a first aspect, the present invention provides a method for preparing a negative ion-releasing activated carbon composite purification material, the method comprising:

[0007] S1: Prepare a graphene oxide dispersion, add mesoporous activated carbon powder and urea to obtain a mixture; sonicate it to obtain a reaction precursor solution, perform a hydrothermal reaction, cool naturally after the reaction is completed, take out the hydrogel, wash and pre-freeze, and then freeze-dry to obtain a nitrogen-doped graphene / activated carbon aerogel substrate.

[0008] S2: Hydrophobic core-shell upconversion nanoparticles are dispersed in chloroform to obtain a dispersion. An equal volume of sodium citrate solution is added to the dispersion, and the pH is adjusted to obtain a treatment solution. The treatment solution is ultrasonically emulsified, allowed to stand and separate into phases, the upper aqueous phase is collected, centrifuged, washed, and the product is dispersed in deionized water to obtain a hydrophilic core-shell upconversion nanoparticle dispersion. A nitrogen-doped graphene / activated carbon aerogel substrate is impregnated in an ethanol dispersion of bismuth oxyiodide / bismuth ferrite heterojunction to obtain a reaction solution F. After ultrasonic treatment at room temperature, it is dried to obtain an aerogel intermediate loaded with heterojunction. The aerogel intermediate loaded with heterojunction is impregnated in a hydrophilic core-shell upconversion nanoparticle dispersion to obtain a reaction solution G. After ultrasonic treatment, the composite gel is freeze-dried to obtain a negative ion releasing activated carbon composite purification material.

[0009] The preparation method of the hydrophobic core-shell structured upconversion nanoparticles is as follows:

[0010] S21: Rare earth acetate is added to a mixed solvent to obtain a mixed dispersion. The mixed dispersion is heated under argon protection and then stirred under vacuum to obtain a rare earth oleate precursor solution. The solution is cooled and a methanol solution of sodium hydroxide and a methanol solution of ammonium fluoride are added to obtain reaction solution A. After stirring, the temperature is raised to evaporate the methanol and then the temperature is raised again to react. After cooling, an oil phase dispersion of core nanoparticles is obtained. The rare earth acetate is yttrium acetate, ytterbium acetate and thulium acetate.

[0011] S22: Yttrium acetate was dispersed in a mixed solvent to obtain a shell precursor solution. After heating under argon protection, the solution was stirred under vacuum to obtain a yttrium oleate precursor solution. After cooling, the solution was added to the oil phase dispersion of the core nanoparticles to obtain reaction solution B. The reaction solution B was added to a methanol solution of sodium hydroxide and a methanol solution of ammonium fluoride to obtain reaction solution C. After stirring, the methanol was evaporated and the reaction was carried out at a higher temperature. After cooling to room temperature, anhydrous ethanol was added to break the emulsion. The solution was centrifuged, washed, and dried to obtain hydrophobic core-shell upconversion nanoparticles.

[0012] The preparation method of the bismuth oxyiodide / bismuth ferrite heterojunction is as follows:

[0013] S23: Bismuth nitrate and ferric nitrate are dispersed in nitric acid solution to obtain a mixed salt solution. The mixed salt solution is added dropwise to potassium hydroxide solution to obtain a suspension. The suspension is subjected to hydrothermal reaction, centrifuged, and the precipitate is washed alternately with second nitric acid and deionized water. The precipitate is then washed with water until the supernatant reaches 7.0-7.2. The precipitate is dried to obtain bismuth ferrite particles. The bismuth ferrite particles are dispersed in ethylene glycol, and bismuth nitrate and polyvinylpyrrolidone are added to obtain reaction solution D. After continuous stirring, potassium iodide in ethylene glycol solution is added dropwise to obtain reaction solution E. The mixture is stirred, centrifuged, washed, and dried to obtain bismuth iodide oxide / bismuth ferrite heterojunction.

[0014] As a preferred technical solution of the present invention, in step S1, the concentration of the graphene oxide dispersion is 2-5 mg / mL, for example, it can be 2.0 mg / mL, 2.3 mg / mL, 2.6 mg / mL, 2.9 mg / mL, 3.2 mg / mL, 3.5 mg / mL, 3.8 mg / mL, 4.1 mg / mL, 4.4 mg / mL, 4.7 mg / mL or 5.0 mg / mL, but it is not limited to the listed values, and other unlisted values ​​within this range are also applicable.

[0015] In some optional embodiments, the mass ratio of graphene oxide, mesoporous activated carbon powder and urea is 1:(0.5-1.5):(20-40), for example, it can be 1:(0.5, 0.6, 0.7, 0.8, 0.9, 1.0, 1.1, 1.2, 1.3, 1.4 or 1.5):(20, 22, 24, 26, 28, 30, 32, 34, 36, 38 or 40), but is not limited to the listed values, and other unlisted values ​​within this range are also applicable.

[0016] In some alternative embodiments, the temperature for ultrasonic treatment of the mixture is 60-90°C, for example, 60°C, 63°C, 66°C, 69°C, 72°C, 75°C, 78°C, 81°C, 84°C, 87°C or 90°C, but is not limited to the listed values, and other unlisted values ​​within this range are also applicable.

[0017] In some alternative embodiments, the ultrasonic treatment time of the mixture is 1-2 hours, for example, 1.0 hours, 1.1 hours, 1.2 hours, 1.3 hours, 1.4 hours, 1.5 hours, 1.6 hours, 1.7 hours, 1.8 hours, 1.9 hours or 2.0 hours, but is not limited to the listed values, and other unlisted values ​​within this range are also applicable.

[0018] In some optional embodiments, the temperature of the hydrothermal reaction of the precursor liquid is 160-200°C, for example, it can be 160°C, 164°C, 168°C, 172°C, 176°C, 180°C, 184°C, 188°C, 192°C, 196°C or 200°C, but is not limited to the listed values, and other unlisted values ​​within this range are also applicable.

[0019] In some optional embodiments, the hydrothermal reaction time of the precursor solution is 10-18 h, for example, it can be 10.0 h, 10.8 h, 11.6 h, 12.4 h, 13.2 h, 14.0 h, 14.8 h, 15.6 h, 16.4 h, 17.2 h or 18.0 h, but is not limited to the listed values, other unlisted values ​​within this range are also applicable.

[0020] In some optional embodiments, the pre-freezing temperature of the hydrogel is -80 to -50°C, for example, it can be -80°C, -77°C, -74°C, -71°C, -68°C, -65°C, -62°C, -59°C, -56°C, -53°C or -50°C, but is not limited to the listed values, other unlisted values ​​within this range are also applicable.

[0021] In some optional embodiments, the pre-freezing time of the hydrogel is 4-8 hours, for example, 4.0 hours, 4.4 hours, 4.8 hours, 5.2 hours, 5.6 hours, 6.0 hours, 6.4 hours, 6.8 hours, 7.2 hours, 7.6 hours, or 8.0 hours, but is not limited to the listed values; other unlisted values ​​within this range are also applicable.

[0022] As a preferred technical solution of the present invention, in step S2, the concentration of the hydrophobic core-shell structure upconversion nanoparticle dispersion is 5-10 mg / mL, for example, it can be 5.0 mg / mL, 5.5 mg / mL, 6.0 mg / mL, 6.5 mg / mL, 7.0 mg / mL, 7.5 mg / mL, 8.0 mg / mL, 8.5 mg / mL, 9.0 mg / mL, 9.5 mg / mL or 10.0 mg / mL, but is not limited to the listed values, other unlisted values ​​within this range are also applicable.

[0023] In some alternative embodiments, the concentration of the sodium citrate solution is 0.1-0.5M, for example, it can be 0.10M, 0.14M, 0.18M, ​​0.22M, 0.26M, 0.30M, 0.34M, 0.38M, 0.42M, 0.46M or 0.50M, but is not limited to the listed values, other unlisted values ​​within this range are also applicable.

[0024] In some alternative embodiments, the pH value of the treatment solution is 9-10, for example, it may be 9.0, 9.1, 9.2, 9.3, 9.4, 9.5, 9.6, 9.7, 9.8, 9.9 or 10.0, but is not limited to the listed values, other unlisted values ​​within this range are also applicable.

[0025] In some optional embodiments, the ultrasonic emulsification temperature of the treatment fluid is 40-60°C, for example, 40°C, 42°C, 44°C, 46°C, 48°C, 50°C, 52°C, 54°C, 56°C, 58°C or 60°C, but is not limited to the listed values, and other unlisted values ​​within this range are also applicable.

[0026] In some optional embodiments, the ultrasonic emulsification time of the treatment solution is 4-8 hours, for example, 4.0 hours, 4.4 hours, 4.8 hours, 5.2 hours, 5.6 hours, 6.0 hours, 6.4 hours, 6.8 hours, 7.2 hours, 7.6 hours or 8.0 hours, but is not limited to the listed values, and other unlisted values ​​within this range are also applicable.

[0027] In some optional embodiments, the concentration of the hydrophilic core-shell upconversion nanoparticle dispersion is 5-10 mg / mL, for example, it can be 5.0 mg / mL, 5.5 mg / mL, 6.0 mg / mL, 6.5 mg / mL, 7.0 mg / mL, 7.5 mg / mL, 8.0 mg / mL, 8.5 mg / mL, 9.0 mg / mL, 9.5 mg / mL or 10.0 mg / mL, but is not limited to the listed values, other unlisted values ​​within this range are also applicable.

[0028] In some optional embodiments, the concentration of the ethanol dispersion of the bismuth oxyiodide / bismuth ferrite heterojunction is 1-4 mg / mL, for example, it can be 1.0 mg / mL, 1.3 mg / mL, 1.6 mg / mL, 1.9 mg / mL, 2.2 mg / mL, 2.5 mg / mL, 2.8 mg / mL, 3.1 mg / mL, 3.4 mg / mL, 3.7 mg / mL or 4.0 mg / mL, but is not limited to the listed values, and other unlisted values ​​within this range are also applicable.

[0029] In some optional embodiments, the mass ratio of the nitrogen-doped graphene / activated carbon aerogel substrate to the bismuth oxyiodide / bismuth ferrite heterojunction is 10:(1-3), for example, it can be 10:1.0, 10:1.2, 10:1.4, 10:1.6, 10:1.8, 10:2.0, 10:2.2, 10:2.4, 10:2.6, 10:2.8 or 10:3.0, but is not limited to the listed values, other unlisted values ​​within this range are also applicable.

[0030] In some optional embodiments, the ultrasonic treatment time of the reaction solution F at room temperature is 30-60 min, for example, it can be 30 min, 33 min, 36 min, 39 min, 42 min, 45 min, 48 min, 51 min, 54 min, 57 min or 60 min, but is not limited to the listed values, and other unlisted values ​​within this range are also applicable.

[0031] In some optional embodiments, the reaction solution F is ultrasonically treated at room temperature and then dried at 60-80°C to obtain an aerogel intermediate loaded with heterostructures. For example, it can be dried at 60°C, 62°C, 64°C, 66°C, 68°C, 70°C, 72°C, 74°C, 76°C, 78°C or 80°C, but is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0032] In some optional embodiments, the mass ratio of the aerogel intermediate loaded with heterostructure to the hydrophilic core-shell upconversion nanoparticles is 100:(2-5), for example, it can be 100:2.0, 100:2.3, 100:2.6, 100:2.9, 100:3.2, 100:3.5, 100:3.8, 100:4.1, 100:4.4, 100:4.7 or 100:5.0, but is not limited to the listed values, other unlisted values ​​within this range are also applicable.

[0033] In some optional embodiments, the ultrasonic treatment time of the reaction solution G is 30-60 min, for example, it can be 30 min, 33 min, 36 min, 39 min, 42 min, 45 min, 48 min, 51 min, 54 min, 57 min or 60 min, but is not limited to the listed values, and other unlisted values ​​within this range are also applicable.

[0034] As a preferred embodiment of the present invention, in step S21, the molar ratio of yttrium acetate, ytterbium acetate, and thulium acetate in the mixed dispersion is (78-80):(20-22):(0.2-0.5), for example, it can be (78.0, 78.2, 78.4, 78.6, 78.8, 79, 79.2, 79.4, 79.6, 79.8, or 80):(20.0, 2...). 0.2, 20.4, 20.6, 20.8, 21.0, 21.2, 21.4, 21.6, 21.8 or 22.0: (0.20, 0.23, 0.26, 0.29, 0.32, 0.35, 0.38, 0.41, 0.44, 0.47 or 0.50), but not limited to the listed values; other unlisted values ​​within this range also apply.

[0035] In some optional embodiments, the mixed solvent is a mixture of oleic acid and 1-octadecene, wherein the volume ratio of oleic acid to 1-octadecene is 1:(1-1.5), for example, it can be 1:1.00, 1:1.05, 1:1.10, 1:1.15, 1:1.20, 1:1.25, 1:1.30, 1:1.35, 1:1.40, 1:1.45 or 1:1.50, but is not limited to the listed values, other unlisted values ​​within this range are also applicable.

[0036] In some optional embodiments, the ratio of the total molar amount of rare earth acetate to the volume of 1-octadecene is 1 mmol:(10-20) mL, for example, it can be 1 mmol:10 mL, 1 mmol:11 mL, 1 mmol:12 mL, 1 mmol:13 mL, 1 mmol:14 mL, 1 mmol:15 mL, 1 mmol:16 mL, 1 mmol:17 mL, 1 mmol:18 mL, 1 mmol:19 mL or 1 mmol:20 mL, but is not limited to the values ​​listed, other unlisted values ​​within this range are also applicable.

[0037] In some optional embodiments, the mixed dispersion is heated to 140-160°C under argon protection, for example to 140°C, 142°C, 144°C, 146°C, 148°C, 150°C, 152°C, 154°C, 156°C, 158°C or 160°C, but is not limited to the listed values, and other unlisted values ​​within this range are also applicable.

[0038] In some optional embodiments, the mixed dispersion is vacuum stirred under argon protection for 1-1.5 hours, for example, 1.00 hours, 1.05 hours, 1.10 hours, 1.15 hours, 1.20 hours, 1.25 hours, 1.30 hours, 1.35 hours, 1.40 hours, 1.45 hours, or 1.50 hours, but is not limited to the listed values; other unlisted values ​​within this range are also applicable.

[0039] In some optional embodiments, the rare earth oleate precursor solution is cooled to 50-70°C, for example, to 50°C, 52°C, 54°C, 56°C, 58°C, 60°C, 62°C, 64°C, 66°C, 68°C or 70°C, but is not limited to the listed values, and other unlisted values ​​within this range are also applicable.

[0040] In some optional embodiments, the molar ratio of sodium hydroxide to the total molar amount of rare earth acetate in the reaction solution A is (2-3):1, for example, it can be 2.0:1, 2.1:1, 2.2:1, 2.3:1, 2.4:1, 2.5:1, 2.6:1, 2.7:1, 2.8:1, 2.9:1 or 3.0:1, but is not limited to the listed values, other unlisted values ​​within this range are also applicable.

[0041] In some optional embodiments, the molar ratio of ammonium fluoride to the total molar amount of rare earth acetate in the reaction solution A is (3.5-4.5):1, for example, it can be 3.5:1, 3.6:1, 3.7:1, 3.8:1, 3.9:1, 4.0:1, 4.1:1, 4.2:1, 4.3:1, 4.4:1 or 4.5:1, but is not limited to the listed values, other unlisted values ​​within this range are also applicable.

[0042] In some optional embodiments, the stirring time of the reaction solution A is 30-50 min, for example, it can be 30 min, 32 min, 34 min, 36 min, 38 min, 40 min, 42 min, 44 min, 46 min or 48 min, 50 min, but is not limited to the listed values, and other unlisted values ​​within this range are also applicable.

[0043] In some optional embodiments, the heating rate of the reaction solution A after stirring to evaporate methanol is 2-4℃ / min, for example, it can be 2℃ / min, 2.2℃ / min, 2.4℃ / min, 2.6℃ / min, 2.8℃ / min, 3℃ / min, 3.2℃ / min, 3.4℃ / min, 3.6℃ / min, 3.8℃ / min or 4℃ / min, but is not limited to the listed values, other unlisted values ​​within this range are also applicable.

[0044] In some optional embodiments, the reaction solution A is heated to 110-120°C to evaporate methanol, for example, 110°C, 111°C, 112°C, 113°C, 114°C, 115°C, 116°C, 117°C, 118°C, 119°C or 120°C, but is not limited to the listed values, and other unlisted values ​​within this range are also applicable.

[0045] In some optional embodiments, the time for evaporating methanol by heating reaction solution A is 15-20 min, for example, it can be 15 min, 15.5 min, 16 min, 16.5 min, 17 min, 17.5 min, 18 min, 18.5 min, 19 min, 19.5 min or 20 min, but is not limited to the listed values, other unlisted values ​​within this range are also applicable.

[0046] In some optional embodiments, the heating rate of the reaction solution A after stirring, heating to evaporate methanol, and then heating again is 5-10℃ / min, for example, it can be 5℃ / min, 5.5℃ / min, 6℃ / min, 6.5℃ / min, 7℃ / min, 7.5℃ / min, 8℃ / min, 8.5℃ / min, 9℃ / min, 9.5℃ / min or 10℃ / min, but is not limited to the listed values, other unlisted values ​​within this range are also applicable.

[0047] In some optional embodiments, the reaction solution A is stirred and then heated to evaporate methanol, and then heated to 300-330°C. For example, it can be heated to 300°C, 303°C, 306°C, 309°C, 312°C, 315°C, 318°C, 321°C, 324°C, 327°C, or 330°C, but it is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0048] In some optional embodiments, the reaction time after stirring the reaction solution A, heating to evaporate the methanol, and then heating again is 1-2 hours, for example, 1.0h, 1.1h, 1.2h, 1.3h, 1.4h, 1.5h, 1.6h, 1.7h, 1.8h, 1.9h, or 2.0h, but is not limited to the listed values; other unlisted values ​​within this range are also applicable.

[0049] As a preferred technical solution of the present invention, in step S22, the mixed solvent is a mixed solvent of oleic acid and 1-octadecene, wherein the volume ratio of oleic acid to 1-octadecene is 1:(1-1.5), for example, it can be 1:1.00, 1:1.05, 1:1.10, 1:1.15, 1:1.20, 1:1.25, 1:1.30, 1:1.35, 1:1.40, 1:1.45 or 1:1.50, but is not limited to the listed values, and other unlisted values ​​within this range are also applicable.

[0050] In some optional embodiments, the molar ratio of yttrium acetate to 1-octadecene in the shell precursor solution is 1 mmol:(5-10) mL, for example, it can be 1 mmol:5.0 mL, 1 mmol:5.5 mL, 1 mmol:6.0 mL, 1 mmol:6.5 mL, 1 mmol:7.0 mL, 1 mmol:7.5 mL, 1 mmol:8.0 mL, 1 mmol:8.5 mL, 1 mmol:9.0 mL, 1 mmol:9.5 mL or 1 mmol:10.0 mL, but is not limited to the listed values, other unlisted values ​​within this range are also applicable.

[0051] In some optional embodiments, the shell precursor solution is heated to 140-160°C under argon protection, for example to 140°C, 142°C, 144°C, 146°C, 148°C, 150°C, 152°C, 154°C, 156°C, 158°C or 160°C, but is not limited to the listed values, and other unlisted values ​​within this range are also applicable.

[0052] In some optional embodiments, the shell precursor solution is vacuum stirred under argon protection for 1-1.5 hours, for example, 1.00 hours, 1.05 hours, 1.10 hours, 1.15 hours, 1.20 hours, 1.25 hours, 1.30 hours, 1.35 hours, 1.40 hours, 1.45 hours, or 1.50 hours, but is not limited to the listed values; other unlisted values ​​within this range are also applicable.

[0053] In some optional embodiments, the molar ratio of yttrium acetate in the shell precursor solution to the total molar amount of rare earth acetate in the mixed dispersion in S21 is (0.3-0.6):1, for example, it can be 0.30:1, 0.33:1, 0.36:1, 0.39:1, 0.42:1, 0.45:1, 0.48:1, 0.51:1, 0.54:1, 0.57:1 or 0.60:1, but is not limited to the listed values, other unlisted values ​​within this range are also applicable.

[0054] In some optional embodiments, the molar ratio of sodium hydroxide to yttrium acetate in the shell precursor solution is (2-3):1, for example, it can be 2.0:1, 2.1:1, 2.2:1, 2.3:1, 2.4:1, 2.5:1, 2.6:1, 2.7:1, 2.8:1, 2.9:1 or 3.0:1, but is not limited to the listed values, other unlisted values ​​within this range are also applicable.

[0055] In some optional embodiments, the molar ratio of ammonium fluoride to yttrium acetate in the shell precursor solution is (3.5-4.5):1, for example, it can be 3.5:1, 3.6:1, 3.7:1, 3.8:1, 3.9:1, 4.0:1, 4.1:1, 4.2:1, 4.3:1, 4.4:1 or 4.5:1, but is not limited to the listed values, other unlisted values ​​within this range are also applicable.

[0056] In some optional embodiments, the stirring time of the reaction solution C is 30-50 min, for example, it can be 30 min, 32 min, 34 min, 36 min, 38 min, 40 min, 42 min, 44 min, 46 min, 48 min or 50 min, but is not limited to the listed values, and other unlisted values ​​within this range are also applicable.

[0057] In some optional embodiments, the heating rate of the reaction solution C after stirring to evaporate methanol is 2-4℃ / min, for example, it can be 2℃ / min, 2.2℃ / min, 2.4℃ / min, 2.6℃ / min, 2.8℃ / min, 3℃ / min, 3.2℃ / min, 3.4℃ / min, 3.6℃ / min, 3.8℃ / min or 4℃ / min, but is not limited to the listed values, other unlisted values ​​within this range are also applicable.

[0058] In some optional embodiments, the reaction solution C is heated to 110-120°C to evaporate methanol, for example, 110°C, 111°C, 112°C, 113°C, 114°C, 115°C, 116°C, 117°C, 118°C, 119°C or 120°C, but is not limited to the listed values, and other unlisted values ​​within this range are also applicable.

[0059] In some optional embodiments, the time for evaporating methanol by heating the reaction solution C is 15-20 min, for example, 15 min, 15.5 min, 16 min, 16.5 min, 17 min, 17.5 min, 18 min, 18.5 min, 19 min, 19.5 min or 20 min, but is not limited to the listed values, and other unlisted values ​​within this range are also applicable.

[0060] In some optional embodiments, the heating rate of the reaction solution C after stirring, heating to evaporate methanol, and then heating again is 5-10℃ / min, for example, it can be 5℃ / min, 5.5℃ / min, 6℃ / min, 6.5℃ / min, 7℃ / min, 7.5℃ / min, 8℃ / min, 8.5℃ / min, 9℃ / min, 9.5℃ / min or 10℃ / min, but is not limited to the listed values, other unlisted values ​​within this range are also applicable.

[0061] In some optional embodiments, the reaction solution C is stirred, heated to evaporate methanol, and then heated to 300-330°C. For example, it can be heated to 300°C, 303°C, 306°C, 309°C, 312°C, 315°C, 318°C, 321°C, 324°C, 327°C, or 330°C, but it is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0062] In some optional embodiments, the reaction time after stirring the reaction solution C, heating to evaporate methanol, and then heating again is 60-90 min, for example, 60 min, 63 min, 66 min, 69 min, 72 min, 75 min, 78 min, 81 min, 84 min, 87 min, or 90 min, but is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0063] As a preferred technical solution of the present invention, in step S23, the concentration of the dilute nitric acid solution is 0.5-1.5M, for example, it can be 0.5M, 0.6M, 0.7M, 0.8M, 0.9M, 1.0M, 1.1M, 1.2M, 1.3M, 1.4M or 1.5M, but it is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0064] In some optional embodiments, the molar ratio of bismuth nitrate to ferric nitrate in the mixed salt solution is (1-1.05):1, for example, it can be 1.000:1, 1.005:1, 1.010:1, 1.015:1, 1.020:1, 1.025:1, 1.030:1, 1.035:1, 1.040:1, 1.045:1 or 1.050:1, but is not limited to the listed values, other unlisted values ​​within this range are also applicable.

[0065] In some alternative embodiments, the concentration of the potassium hydroxide solution is 4-8M, for example, it can be 4.0M, 4.4M, 4.8M, 5.2M, 5.6M, 6.0M, 6.4M, 6.8M, 7.2M, 7.6M or 8.0M, but is not limited to the listed values, other unlisted values ​​within this range are also applicable.

[0066] In some alternative embodiments, the pH value of the suspension is 12-13, for example, it may be 12.0, 12.1, 12.2, 12.3, 12.4, 12.5, 12.6, 12.7, 12.8, 12.9 or 13.0, but is not limited to the listed values, other unlisted values ​​within this range are also applicable.

[0067] In some optional embodiments, the temperature of the hydrothermal reaction of the suspension is 200-240°C, for example, 200°C, 204°C, 208°C, 212°C, 216°C, 220°C, 224°C, 228°C, 232°C, 236°C or 240°C, but is not limited to the listed values, and other unlisted values ​​within this range are also applicable.

[0068] In some optional embodiments, the hydrothermal reaction time of the suspension is 24-48 hours, for example, 24.0 hours, 26.4 hours, 28.8 hours, 31.2 hours, 33.6 hours, 36.0 hours, 38.4 hours, 40.8 hours, 43.2 hours, 45.6 hours, or 48.0 hours, but is not limited to the listed values; other unlisted values ​​within this range are also applicable.

[0069] In some alternative embodiments, the washing is performed by alternating washing with a second nitric acid of a concentration of 0.2-0.5M and deionized water. For example, the concentration of the second nitric acid can be 0.20M, 0.23M, 0.26M, 0.29M, 0.32M, 0.35M, 0.38M, 0.41M, 0.44M, 0.47M or 0.50M, but is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0070] In some optional embodiments, the mass ratio of bismuth ferrite particles to bismuth nitrate in the reaction solution D is 1:(4-8), for example, it can be 1:4.0, 1:4.4, 1:4.8, 1:5.2, 1:5.6, 1:6.0, 1:6.4, 1:6.8, 1:7.2, 1:7.6 or 1:8.0, but is not limited to the listed values, other unlisted values ​​within this range are also applicable.

[0071] In some optional embodiments, the mass ratio of polyvinylpyrrolidone to bismuth nitrate in the reaction solution D is (0.5-1):1, for example, it can be 0.50:1, 0.55:1, 0.60:1, 0.65:1, 0.70:1, 0.75:1, 0.80:1, 0.85:1, 0.90:1, 0.95:1 or 1.00:1, but is not limited to the listed values, other unlisted values ​​within this range are also applicable.

[0072] In some optional embodiments, the reaction solution D is continuously stirred for 30-60 minutes, for example, 30 minutes, 33 minutes, 36 minutes, 39 minutes, 42 minutes, 45 minutes, 48 ​​minutes, 51 minutes, 54 minutes, 57 minutes or 60 minutes, but is not limited to the listed values, and other unlisted values ​​within this range are also applicable.

[0073] In some optional embodiments, the molar ratio of potassium iodide to bismuth nitrate in the reaction solution E is (1-1.2):1, for example, it can be 1.00:1, 1.02:1, 1.04:1, 1.06:1, 1.08:1, 1.10:1, 1.12:1, 1.14:1, 1.16:1, 1.18:1 or 1.20:1, but is not limited to the listed values, other unlisted values ​​within this range are also applicable.

[0074] In some optional embodiments, the reaction temperature of the reaction liquid E is 40-60°C, for example, it can be 40°C, 42°C, 44°C, 46°C, 48°C, 50°C, 52°C, 54°C, 56°C, 58°C or 60°C, but is not limited to the listed values, and other unlisted values ​​within this range are also applicable.

[0075] In some optional embodiments, the reaction time of the reaction solution E is 2-5 hours, for example, 2.0 hours, 2.3 hours, 2.6 hours, 2.9 hours, 3.2 hours, 3.5 hours, 3.8 hours, 4.1 hours, 4.4 hours, 4.7 hours or 5.0 hours, but is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0076] Secondly, the present invention provides a negative ion releasing activated carbon composite purification material.

[0077] This application prepared a nitrogen-doped graphene / activated carbon aerogel substrate, which serves as a structural and functional foundation platform for the entire purification system. First, graphene oxide, as the structural building block, is partially reduced under hydrothermal conditions and self-assembles into a three-dimensional porous network, while mesoporous activated carbon is embedded within it as the physical framework, jointly constructing a composite material with a multi-level pore structure. This structure not only endows the material with a large specific surface area, providing ample sites for the efficient physical adsorption of pollutants such as VOCs and PM2.5 in the air, but also provides open channels for the uniform loading and mass transport of subsequent functional nanoparticles. Second, by introducing urea as a nitrogen source into the reaction system, in-situ nitrogen doping of the graphene framework was achieved. Under hydrothermal conditions, nitrogen-containing species generated by the decomposition of urea can replace or fill the graphene lattice, introducing nitrogen atoms in various forms such as pyridine nitrogen and pyrrole nitrogen. These nitrogen sites not only enhance the chemisorption of specific gas molecules, but more importantly, as highly active coordination sites, they can fix the subsequently loaded functional nanoparticles through chemical forces, enhancing the interfacial bonding strength. Freeze-drying avoids the damage to the porous structure caused by the surface tension of water, preserving its three-dimensional network and ensuring the material's low density, high porosity, and structural integrity.

[0078] This application prepares core-shell structured upconversion nanoparticles that convert ubiquitous, low-energy near-infrared photons—which are unusable by traditional photocatalysis—into high-energy ultraviolet / blue photons. The mechanism is based on energy transfer upconversion between rare-earth ions: first, ytterbium ions, acting as sensitizers, efficiently absorb the energy of external near-infrared photons and transition to an excited state; subsequently, through non-radiative energy transfer, the energy is transferred to thulium ions, acting as activators, causing them to transition to an intermediate metastable energy level; when a second near-infrared photon is absorbed and energy is transferred again, the metastable thulium ions continue to absorb energy, transitioning to a higher excited state energy level; finally, the excited thulium ions transition back to the ground state, releasing high-energy photons (such as ultraviolet and blue light) with energy far exceeding that of a single near-infrared photon. The core-shell structure synthesized in this application aims to achieve "surface passivation": first, a luminescent core containing ytterbium and thulium ions is synthesized, and then an inert shell without luminescent ions is coated onto its surface. This inert shell can effectively repair lattice defects and dangling bonds on the core surface, isolate the luminescent center from the external environment, thereby suppressing the surface quenching effect that leads to energy loss and improving the upconversion luminescence efficiency.

[0079] This application introduces a bismuth oxyiodide / bismuth ferrite heterojunction, which is the core catalytic and energy conversion unit of the system. First, bismuth ferrite nanoparticles synthesized via a high-temperature hydrothermal method possess excellent piezoelectric effects due to their non-centrosymmetric crystal structure. When the material is subjected to weak mechanical disturbances such as airflow, a piezoelectric potential field is generated internally. Second, a heterojunction is constructed by in-situ growth of bismuth oxyiodide nanosheets on the surface of bismuth ferrite. Bismuth oxyiodide, as a narrow bandgap semiconductor, is responsible for efficiently absorbing ultraviolet / blue photons provided by the core-shell upconversion nanoparticles and generating initial electron-hole pairs. Subsequently, under the action of the piezoelectric potential field generated by bismuth ferrite, this strong built-in electric field acts as a "charge pump," actively and forcefully separating photogenerated electrons and holes generated in bismuth oxyiodide and driving electrons to the material surface. This built-in electric field and piezoelectric potential synergistically achieve active charge separation and suppress photogenerated carrier recombination. Electrons enriched on the material surface interact with adsorbed oxygen to preferentially generate negatively charged reactive oxygen species such as superoxide anions, which then synergistically participate in the oxidative degradation of organic matter with holes / ·OH.

[0080] Synergistic effects also exist in this application. First, the nitrogen-doped graphene / activated carbon aerogel substrate efficiently captures and immobilizes pollutants. Simultaneously, core-shell upconversion nanoparticles capture near-infrared photons from the environment and convert them into high-energy ultraviolet / blue photons, providing the light energy required for the photochemical reaction of the system. This constitutes the "upconversion energy supply" synergistic effect of the system. These internally generated photons are absorbed by the adjacent bismuth oxyiodide / bismuth ferrite heterojunction, generating photogenerated electron-hole pairs. Subsequently, when the airflow causes microscopic vibration of the material, the piezoelectric effect of bismuth ferrite is activated, and the resulting piezoelectric potential field acts on the bismuth oxyiodide / bismuth ferrite heterojunction interface, triggering the "piezoelectric / photoelectronic" synergistic effect, improving the separation efficiency of photogenerated charges, and realizing the material's response to mechanical energy input. High-energy electrons enriched on the surface react with oxygen to generate negatively charged reactive species such as superoxide anions. These negatively charged reactive species, along with the separated holes, constitute highly oxidizing reactive species, capable of efficiently degrading adsorbed pollutants into inorganic small molecules nearby, and achieving partial regeneration of the substrate adsorption sites. The entire system realizes the capture of low-quality energy (near-infrared light, mechanical vibration), the internal conversion of energy forms, and the enhancement of catalytic performance, constructing a complete and highly efficient negative ion-releasing activated carbon composite purification material.

[0081] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0082] This application prepares a nitrogen-doped graphene / activated carbon aerogel substrate. The substrate utilizes its huge specific surface area and hierarchical pore structure to efficiently adsorb pollutants. At the same time, the in-situ introduced nitrogen doping sites not only enhance the chemical adsorption capacity, but also serve as highly active anchors to improve the interfacial bonding strength with functional nanoparticles, thereby ensuring the structural stability of the entire composite material system.

[0083] This application achieves the conversion of low-energy near-infrared light into high-energy ultraviolet / blue light by preparing core-shell structured upconversion nanoparticles: the sensitizer (ytterbium ions) absorbs near-infrared photons multiple times and relays the energy to the activator (thulium ions), ultimately releasing high-energy photons. The core-shell structure, by passivating surface defects, suppresses energy loss, thereby improving the upconversion luminescence efficiency.

[0084] The bismuth oxyiodide / bismuth ferrite heterojunction introduced in this application achieves efficient energy conversion through the synergistic effect of piezoelectricity and photoelectricity. The piezoelectric bismuth ferrite generates an electric field under airflow disturbance, which greatly promotes the separation efficiency of photogenerated charges in the photosensitive bismuth oxyiodide and drives electrons to the material surface, ultimately efficiently reducing oxygen to negative ions.

[0085] This application involves enriching pollutants on a substrate; then, upconversion particles convert near-infrared light into an internal light source, exciting a heterojunction to generate photogenerated charges; driven by airflow, the piezoelectric effect of the heterojunction generates a strong electric field, greatly improving charge separation efficiency, and ultimately generating negatively charged reactive species such as superoxide anions and free radicals to degrade pollutants. This application achieves the synergistic utilization of light and mechanical energy in the environment, constructing a highly efficient intelligent responsive purification material. Detailed Implementation

[0086] The technical solution of the present invention will be described in detail below with reference to specific embodiments. The embodiments described herein are specific implementations of the present invention and are used to illustrate the concept of the present invention; these descriptions are explanatory and exemplary and should not be construed as limiting the implementation of the present invention or the scope of protection of the present invention. In addition to the embodiments described herein, those skilled in the art can also adopt other obvious technical solutions based on the content disclosed in the claims and the specification of this application. These technical solutions include technical solutions that employ any obvious substitutions and modifications made to the embodiments described herein.

[0087] The chemical reagents used in the embodiments and comparative examples of this invention are all commercially available products and have not undergone further purification or processing.

[0088] Example 1

[0089] This embodiment provides a negative ion-releasing activated carbon composite purification material and its preparation method. The preparation method of the negative ion-releasing activated carbon composite purification material specifically includes the following steps:

[0090] S1: Prepare a graphene oxide dispersion with a concentration of 4 mg / mL, add mesoporous activated carbon powder and urea to obtain a mixture, wherein the mass ratio of graphene oxide, mesoporous activated carbon powder and urea is 1:1.2:35; sonicate it at 85℃ for 1.8 h to obtain a reaction precursor solution, and hydrothermally react it at 185℃ for 15 h. After the reaction is completed, cool it naturally, take out the hydrogel, wash it and pre-freeze it at -60℃ for 7 h, and then freeze-dry it to obtain a nitrogen-doped graphene / activated carbon aerogel substrate.

[0091] S2: Hydrophobic core-shell upconversion nanoparticles were dispersed in chloroform to obtain a dispersion with a concentration of 8 mg / mL. An equal volume of 0.4 M sodium citrate solution was added to the dispersion, and the pH was adjusted to 9.8 to obtain a treatment solution. The treatment solution was ultrasonically emulsified at 52 °C for 7 h. After standing and phase separation, the upper aqueous phase was collected, centrifuged, washed, and the product was dispersed in deionized water to obtain a hydrophilic core-shell upconversion nanoparticle dispersion with a concentration of 9 mg / mL. A nitrogen-doped graphene / activated carbon aerogel substrate was impregnated in an ethanol dispersion of bismuth oxyiodide / bismuth ferrite heterostructure with a concentration of 3.5 mg / mL. A reaction solution F was obtained, wherein the mass ratio of nitrogen-doped graphene / activated carbon aerogel substrate to bismuth oxyiodide / bismuth ferrite heterojunction was 10:2.5. After ultrasonic treatment at room temperature for 50 min, it was dried at 75 °C to obtain an aerogel intermediate loaded with heterojunction. The aerogel intermediate loaded with heterojunction was then impregnated in a dispersion of hydrophilic core-shell structured upconversion nanoparticles to obtain a reaction solution G, wherein the mass ratio of the aerogel intermediate loaded with heterojunction to hydrophilic core-shell structured upconversion nanoparticles was 100:4. After ultrasonic treatment for 45 min, the composite gel was freeze-dried to obtain a negative ion releasing activated carbon composite purification material.

[0092] The preparation method of the hydrophobic core-shell structured upconversion nanoparticles is as follows:

[0093] S21: Rare earth acetates are added to a mixed solvent to obtain a mixed dispersion, wherein the rare earth acetates are yttrium acetate, ytterbium acetate, and thulium acetate, and the molar ratio of yttrium acetate, ytterbium acetate, and thulium acetate is 79:21:0.4. The mixed solvent is oleic acid and 1-octadecene, wherein the volume ratio of oleic acid to 1-octadecene is 1:1.4, and the ratio of the total molar amount of rare earth acetates to the volume of 1-octadecene is 1 mmol:18 mL. The mixed dispersion is heated to 155 °C under argon protection and stirred under vacuum for 1.4 h to obtain rare earth oleate. The precursor solution was cooled to 65°C, and a methanol solution of sodium hydroxide and a methanol solution of ammonium fluoride were added to obtain reaction solution A, wherein the molar ratio of the total molar amount of sodium hydroxide to rare earth acetate was 2.8:1, and the molar ratio of the total molar amount of ammonium fluoride to rare earth acetate was 4.2:1. After stirring for 45 min, the temperature was increased to 114°C at a rate of 3.5°C / min and held for 18 min to evaporate methanol. Then, the temperature was increased to 325°C at a rate of 6°C / min and reacted for 1.8 h. After cooling, an oil phase dispersion of core nanoparticles was obtained.

[0094] S22: Yttrium acetate was dispersed in a mixed solvent to obtain a shell precursor solution, wherein the mixed solvent was oleic acid and 1-octadecene, the volume ratio of oleic acid to 1-octadecene was 1:1.4, and the molar volume ratio of yttrium acetate to 1-octadecene was 1 mmol:8 mL. The solution was heated to 152 °C under argon protection and stirred under vacuum for 1.3 h to obtain a yttrium oleate precursor solution. After cooling, the solution was added to the oil phase dispersion of the core nanoparticles to obtain reaction solution B. The molar ratio of yttrium acetate in the shell precursor solution to the total molar amount of rare earth acetate in the mixed dispersion was 0.5:1. Reaction solution B was prepared by adding a methanol solution of sodium hydroxide and a methanol solution of ammonium fluoride to obtain reaction solution C. The molar ratio of sodium hydroxide to yttrium acetate in the shell precursor solution was 2.6:1, and the molar ratio of ammonium fluoride to yttrium acetate in the shell precursor solution was 4.0:1. After stirring for 42 min, the temperature was increased to 120 °C at a rate of 3 °C / min and held for 18 min to evaporate methanol. Then, the temperature was increased to 315 °C at a rate of 8 °C / min and reacted for 85 min. After cooling to room temperature, anhydrous ethanol was added to break the emulsion. The mixture was centrifuged, washed, and dried to obtain hydrophobic core-shell upconversion nanoparticles.

[0095] The preparation method of the bismuth oxyiodide / bismuth ferrite heterojunction is as follows:

[0096] S23: Bismuth nitrate and ferric nitrate were dispersed in a 1.2M nitric acid solution to obtain a mixed salt solution, wherein the molar ratio of bismuth nitrate to ferric nitrate was 1.04:1. This solution was added dropwise to a 7M potassium hydroxide solution until the pH reached 12.8 to obtain a suspension. The suspension was hydrothermally reacted at 230℃ for 40 hours, centrifuged, and the precipitate was washed alternately with 0.4M secondary nitric acid and deionized water. The precipitate was then washed with water until the pH of the supernatant reached 7.0. The precipitate was dried to obtain bismuth ferrate particles. The iron... Bismuth ferrite particles were dispersed in ethylene glycol. Bismuth nitrate and polyvinylpyrrolidone were added to obtain reaction solution D, in which the mass ratio of bismuth ferrite particles to bismuth nitrate was 1:7 and the mass ratio of polyvinylpyrrolidone to bismuth nitrate was 0.8:1. After stirring continuously for 55 min, a potassium iodide solution in ethylene glycol was added dropwise to obtain reaction solution E, in which the molar ratio of potassium iodide to bismuth nitrate was 1.15:1. The reaction was stirred at 55 °C for 4.5 h. After centrifugation, washing, and drying, bismuth iodide oxide / bismuth ferrite heterojunction was obtained.

[0097] Example 2

[0098] This embodiment provides a negative ion-releasing activated carbon composite purification material and its preparation method. The preparation method of the negative ion-releasing activated carbon composite purification material specifically includes the following steps:

[0099] S1: Prepare a graphene oxide dispersion with a concentration of 2 mg / mL, add mesoporous activated carbon powder and urea to obtain a mixture, wherein the mass ratio of graphene oxide, mesoporous activated carbon powder and urea is 1:0.5:20; sonicate it at 60℃ for 1 h to obtain a reaction precursor solution, and hydrothermally react it at 160℃ for 10 h. After the reaction is completed, cool it naturally, take out the hydrogel, wash it and pre-freeze it at -80℃ for 4 h, and then freeze-dry it to obtain a nitrogen-doped graphene / activated carbon aerogel substrate.

[0100] S2: Hydrophobic core-shell upconversion nanoparticles were dispersed in chloroform to obtain a dispersion with a concentration of 5 mg / mL. An equal volume of 0.1 M sodium citrate solution was added to the dispersion, and the pH was adjusted to 9 to obtain a treatment solution. The treatment solution was ultrasonically emulsified at 60 °C for 4 h. After standing and phase separation, the upper aqueous phase was collected, centrifuged, washed, and the product was dispersed in deionized water to obtain a hydrophilic core-shell upconversion nanoparticle dispersion with a concentration of 5 mg / mL. A nitrogen-doped graphene / activated carbon aerogel substrate was impregnated in an ethanol dispersion of bismuth oxyiodide / bismuth ferrite heterostructure with a concentration of 1 mg / mL to obtain... The reaction solution F, wherein the mass ratio of nitrogen-doped graphene / activated carbon aerogel substrate to bismuth oxyiodide / bismuth ferrite heterojunction is 10:1, is ultrasonically treated at room temperature for 30 min and then dried at 60 °C to obtain an aerogel intermediate loaded with heterojunction. The aerogel intermediate loaded with heterojunction is then impregnated in a dispersion of hydrophilic core-shell structured upconversion nanoparticles to obtain reaction solution G, wherein the mass ratio of the aerogel intermediate loaded with heterojunction to hydrophilic core-shell structured upconversion nanoparticles is 100:2. After ultrasonic treatment for 60 min, the composite gel is freeze-dried to obtain a negative ion releasing activated carbon composite purification material.

[0101] The preparation method of the hydrophobic core-shell structured upconversion nanoparticles is as follows:

[0102] S21: Rare earth acetates are added to a mixed solvent to obtain a mixed dispersion, wherein the rare earth acetates are yttrium acetate, ytterbium acetate, and thulium acetate, and the molar ratio of yttrium acetate, ytterbium acetate, and thulium acetate is 80:20:0.5. The mixed solvent is oleic acid and 1-octadecene, wherein the volume ratio of oleic acid to 1-octadecene is 1:1, and the ratio of the total molar amount of rare earth acetates to the volume of 1-octadecene is 1 mmol:10 mL. The mixed dispersion is heated to 140 °C under argon protection and stirred under vacuum for 1 h to obtain rare earth oleate. The precursor solution was cooled to 50°C, and a methanol solution of sodium hydroxide and a methanol solution of ammonium fluoride were added to obtain reaction solution A, wherein the molar ratio of the total molar amount of sodium hydroxide to rare earth acetate was 2:1, and the molar ratio of the total molar amount of ammonium fluoride to rare earth acetate was 3.5:1. After stirring for 30 min, the temperature was increased to 116°C at a heating rate of 2.5°C / min and held for 17 min to evaporate methanol. Then the temperature was increased to 300°C at a heating rate of 8°C / min and reacted for 1 h. After cooling, an oil phase dispersion of core nanoparticles was obtained.

[0103] S22: Yttrium acetate was dispersed in a mixed solvent to obtain a shell precursor solution, wherein the mixed solvent was oleic acid and 1-octadecene, the volume ratio of oleic acid to 1-octadecene was 1:1, and the molar volume ratio of yttrium acetate to 1-octadecene was 1 mmol: 5 mL. The solution was heated to 160 °C under argon protection and stirred under vacuum for 1.5 h to obtain a yttrium oleate precursor solution. After cooling, this solution was added to the oil phase dispersion of the core nanoparticles to obtain reaction solution B. The molar ratio of yttrium acetate in the shell precursor solution to the total molar amount of rare earth acetate in the mixed dispersion was 0.3:1. Reaction solution B was prepared by adding a methanol solution of sodium hydroxide and a methanol solution of ammonium fluoride to obtain reaction solution C. The molar ratio of sodium hydroxide to yttrium acetate in the shell precursor solution was 2:1, and the molar ratio of ammonium fluoride to yttrium acetate in the shell precursor solution was 3.5:1. After stirring for 50 min, the temperature was increased to 110 °C at a rate of 4 °C / min and held for 20 min to evaporate methanol. Then, the temperature was increased to 330 °C at a rate of 7 °C / min and reacted for 60 min. After cooling to room temperature, anhydrous ethanol was added to break the emulsion. The mixture was centrifuged, washed, and dried to obtain hydrophobic core-shell upconversion nanoparticles.

[0104] The preparation method of the bismuth oxyiodide / bismuth ferrite heterojunction is as follows:

[0105] S23: Bismuth nitrate and ferric nitrate were dispersed in a 0.5M nitric acid solution to obtain a mixed salt solution, wherein the molar ratio of bismuth nitrate to ferric nitrate was 1:1. This solution was added dropwise to a 4M potassium hydroxide solution until the pH reached 12 to obtain a suspension. The suspension was hydrothermally reacted at 200℃ for 24 hours. After centrifugation, the precipitate was washed alternately with 0.2M second nitric acid and deionized water, and then washed with water until the pH of the supernatant reached 7.1. The precipitate was dried to obtain bismuth ferrite particles. The bismuth ferrite particles were dispersed in ethylene glycol, and bismuth nitrate and polyvinylpyrrolidone were added to obtain reaction solution D, wherein the mass ratio of bismuth ferrite particles to bismuth nitrate was 1:4, and the mass ratio of polyvinylpyrrolidone to bismuth nitrate was 0.5:1. After stirring continuously for 30 minutes, a potassium iodide solution in ethylene glycol was added dropwise to obtain reaction solution E, wherein the molar ratio of potassium iodide to bismuth nitrate was 1:1. The mixture was stirred at 40℃ for 2 hours, centrifuged, washed, and dried to obtain a bismuth iodide oxide / bismuth ferrite heterojunction.

[0106] Example 3

[0107] This embodiment provides a negative ion-releasing activated carbon composite purification material and its preparation method. The preparation method of the negative ion-releasing activated carbon composite purification material specifically includes the following steps:

[0108] S1: Prepare a graphene oxide dispersion with a concentration of 3 mg / mL, add mesoporous activated carbon powder and urea to obtain a mixture, wherein the mass ratio of graphene oxide, mesoporous activated carbon powder and urea is 1:0.8:25; sonicate it at 70℃ for 1.2 h to obtain a reaction precursor solution, and hydrothermally react it at 170℃ for 12 h. After the reaction is completed, cool it naturally, take out the hydrogel, wash it and pre-freeze it at -75℃ for 5 h, and then freeze-dry it to obtain a nitrogen-doped graphene / activated carbon aerogel substrate;

[0109] S2: Hydrophobic core-shell upconversion nanoparticles were dispersed in chloroform to obtain a dispersion with a concentration of 6 mg / mL. An equal volume of 0.2 M sodium citrate solution was added to the dispersion, and the pH was adjusted to 9.2 to obtain a treatment solution. The treatment solution was ultrasonically emulsified at 58 °C for 5 h. After standing and phase separation, the upper aqueous phase was collected, centrifuged, washed, and the product was dispersed in deionized water to obtain a hydrophilic core-shell upconversion nanoparticle dispersion with a concentration of 7 mg / mL. A nitrogen-doped graphene / activated carbon aerogel substrate was impregnated in an ethanol dispersion of bismuth oxyiodide / bismuth ferrite heterostructure with a concentration of 2 mg / mL to obtain... The reaction solution F, wherein the mass ratio of nitrogen-doped graphene / activated carbon aerogel substrate to bismuth oxyiodide / bismuth ferrite heterojunction is 10:1.5, is ultrasonically treated at room temperature for 40 min and then dried at 65 °C to obtain an aerogel intermediate loaded with heterojunction. The aerogel intermediate loaded with heterojunction is then impregnated in a dispersion of hydrophilic core-shell structured upconversion nanoparticles to obtain reaction solution G, wherein the mass ratio of the aerogel intermediate loaded with heterojunction to hydrophilic core-shell structured upconversion nanoparticles is 100:3. After ultrasonic treatment for 55 min, the composite gel is freeze-dried to obtain a negative ion releasing activated carbon composite purification material.

[0110] The preparation method of the hydrophobic core-shell structured upconversion nanoparticles is as follows:

[0111] S21: Rare earth acetates are added to a mixed solvent to obtain a mixed dispersion, wherein the rare earth acetates are yttrium acetate, ytterbium acetate, and thulium acetate, and the molar ratio of yttrium acetate, ytterbium acetate, and thulium acetate is 78:22:0.2. The mixed solvent is oleic acid and 1-octadecene, wherein the volume ratio of oleic acid to 1-octadecene is 1:1.1, and the ratio of the total molar amount of rare earth acetates to the volume of 1-octadecene is 1 mmol:12 mL. Under argon protection, the mixed dispersion is heated to 145 °C and stirred under vacuum for 1.1 h to obtain rare earth oleic acid. The salt precursor solution was cooled to 55°C, and a methanol solution of sodium hydroxide and a methanol solution of ammonium fluoride were added to obtain reaction solution A, wherein the molar ratio of sodium hydroxide to rare earth acetate was 2.2:1 and the molar ratio of ammonium fluoride to rare earth acetate was 3.8:1. After stirring for 35 min, the temperature was increased to 119°C at a rate of 4°C / min and held for 16 min to evaporate methanol. Then the temperature was increased to 310°C at a rate of 10°C / min and reacted for 1.2 h. After cooling, an oil phase dispersion of core nanoparticles was obtained.

[0112] S22: Yttrium acetate was dispersed in a mixed solvent to obtain a shell precursor solution, wherein the mixed solvent was oleic acid and 1-octadecene, the volume ratio of oleic acid to 1-octadecene was 1:1.1, and the molar volume ratio of yttrium acetate to 1-octadecene was 1 mmol:6 mL. The solution was heated to 148 °C under argon protection and stirred under vacuum for 1.4 h to obtain a yttrium oleate precursor solution. After cooling, this solution was added to the oil phase dispersion of the core nanoparticles to obtain reaction solution B. The molar ratio of yttrium acetate in the shell precursor solution to the total molar amount of rare earth acetate in the mixed dispersion was 0.4:1. Reaction solution B was prepared by adding a methanol solution of sodium hydroxide and a methanol solution of ammonium fluoride to obtain reaction solution C. The molar ratio of sodium hydroxide to yttrium acetate in the shell precursor solution was 2.4:1, and the molar ratio of ammonium fluoride to yttrium acetate in the shell precursor solution was 3.7:1. After stirring for 38 min, the temperature was increased to 115 °C at a rate of 4 °C / min and held for 15 min to evaporate methanol. Then, the temperature was increased to 325 °C at a rate of 5 °C / min and reacted for 70 min. After cooling to room temperature, anhydrous ethanol was added to break the emulsion. The mixture was centrifuged, washed, and dried to obtain hydrophobic core-shell upconversion nanoparticles.

[0113] The preparation method of the bismuth oxyiodide / bismuth ferrite heterojunction is as follows:

[0114] S23: Bismuth nitrate and ferric nitrate were dispersed in a 0.8 M nitric acid solution to obtain a mixed salt solution, wherein the molar ratio of bismuth nitrate to ferric nitrate was 1.01:1. This solution was added dropwise to a 5 M potassium hydroxide solution until the pH reached 12.2, resulting in a suspension. This suspension was hydrothermally reacted at 210 °C for 30 h. After centrifugation, the precipitate was washed alternately with 0.3 M secondary nitric acid and deionized water, followed by water washing until the pH of the supernatant reached 7.2. The precipitate was then dried to obtain bismuth ferrite particles. Bismuth ferrite particles were dispersed in ethylene glycol, and bismuth nitrate and polyvinylpyrrolidone were added to obtain reaction solution D, wherein the mass ratio of bismuth ferrite particles to bismuth nitrate was 1:5, and the mass ratio of polyvinylpyrrolidone to bismuth nitrate was 0.6:1. After stirring continuously for 40 min, a potassium iodide solution in ethylene glycol was added dropwise to obtain reaction solution E, wherein the molar ratio of potassium iodide to bismuth nitrate was 1.05:1. The reaction was stirred at 45 °C for 3 h, centrifuged, washed, and dried to obtain bismuth iodide oxide / bismuth ferrite heterojunction.

[0115] Example 4

[0116] This embodiment provides a negative ion-releasing activated carbon composite purification material and its preparation method. The preparation method of the negative ion-releasing activated carbon composite purification material specifically includes the following steps:

[0117] S1: Prepare a graphene oxide dispersion with a concentration of 5 mg / mL, add mesoporous activated carbon powder and urea to obtain a mixture, wherein the mass ratio of graphene oxide, mesoporous activated carbon powder and urea is 1:1.5:40; sonicate it at 90℃ for 2 h to obtain a reaction precursor solution, and hydrothermally react it at 200℃ for 18 h. After the reaction is completed, cool it naturally, take out the hydrogel, wash it and pre-freeze it at -50℃ for 8 h, and then freeze-dry it to obtain a nitrogen-doped graphene / activated carbon aerogel substrate.

[0118] S2: Hydrophobic core-shell upconversion nanoparticles were dispersed in chloroform to obtain a dispersion with a concentration of 10 mg / mL. An equal volume of 0.5 M sodium citrate solution was added to the dispersion, and the pH was adjusted to 10 to obtain a treatment solution. The treatment solution was ultrasonically emulsified at 40 °C for 8 h. After standing and phase separation, the upper aqueous phase was collected, centrifuged, washed, and the product was dispersed in deionized water to obtain a hydrophilic core-shell upconversion nanoparticle dispersion with a concentration of 10 mg / mL. A nitrogen-doped graphene / activated carbon aerogel substrate was impregnated in an ethanol dispersion of bismuth oxyiodide / bismuth ferrite heterostructure with a concentration of 4 mg / mL. A reaction solution F was obtained, wherein the mass ratio of nitrogen-doped graphene / activated carbon aerogel substrate to bismuth oxyiodide / bismuth ferrite heterojunction was 10:3. After ultrasonic treatment at room temperature for 60 min, it was dried at 80 °C to obtain an aerogel intermediate loaded with heterojunction. The aerogel intermediate loaded with heterojunction was then impregnated in a dispersion of hydrophilic core-shell structured upconversion nanoparticles to obtain a reaction solution G, wherein the mass ratio of the aerogel intermediate loaded with heterojunction to hydrophilic core-shell structured upconversion nanoparticles was 100:5. After ultrasonic treatment for 30 min, the composite gel was freeze-dried to obtain a negative ion releasing activated carbon composite purification material.

[0119] The preparation method of the hydrophobic core-shell structured upconversion nanoparticles is as follows:

[0120] S21: Rare earth acetates are added to a mixed solvent to obtain a mixed dispersion, wherein the rare earth acetates are yttrium acetate, ytterbium acetate, and thulium acetate, and the molar ratio of yttrium acetate, ytterbium acetate, and thulium acetate is 79.5:20.3:0.3. The mixed solvent is oleic acid and 1-octadecene, wherein the volume ratio of oleic acid to 1-octadecene is 1:1.5, and the ratio of the total molar amount of rare earth acetates to the volume of 1-octadecene is 1 mmol:20 mL. The mixed dispersion is heated to 160 °C under argon protection and stirred under vacuum for 1.5 h to obtain... A rare earth oleate precursor solution was cooled to 70°C, and a methanol solution of sodium hydroxide and a methanol solution of ammonium fluoride were added to obtain reaction solution A. The molar ratio of sodium hydroxide to rare earth acetate was 3:1, and the molar ratio of ammonium fluoride to rare earth acetate was 4.5:1. After stirring for 50 min, the temperature was increased to 120°C at a rate of 2°C / min and held for 15 min to evaporate methanol. Then, the temperature was increased to 330°C at a rate of 5°C / min and reacted for 2 h. After cooling, an oil phase dispersion of core nanoparticles was obtained.

[0121] S22: Yttrium acetate is dispersed in a mixed solvent to obtain a shell precursor solution, wherein the mixed solvent is oleic acid and 1-octadecene, the volume ratio of oleic acid to 1-octadecene is 1:1.5, and the molar volume ratio of yttrium acetate to 1-octadecene is 1 mmol:10 mL. Under argon protection, the solution is heated to 140 °C and stirred under vacuum for 1 h to obtain a yttrium oleate precursor solution. After cooling, this solution is added to the oil phase dispersion of the core nanoparticles to obtain reaction solution B. The molar ratio of yttrium acetate in the shell precursor solution to the total molar amount of rare earth acetate in the mixed dispersion is 0.6:1. Reaction solution B was mixed with a methanol solution of sodium hydroxide and a methanol solution of ammonium fluoride to obtain reaction solution C. The molar ratio of sodium hydroxide to yttrium acetate in the shell precursor solution was 3:1, and the molar ratio of ammonium fluoride to yttrium acetate in the shell precursor solution was 4.5:1. After stirring for 30 min, the temperature was increased to 118 °C at a rate of 3.5 °C / min and held for 17 min to evaporate methanol. Then, the temperature was increased to 300 °C at a rate of 10 °C / min and reacted for 90 min. After cooling to room temperature, anhydrous ethanol was added to break the emulsion. The mixture was centrifuged, washed, and dried to obtain hydrophobic core-shell upconversion nanoparticles.

[0122] The preparation method of the bismuth oxyiodide / bismuth ferrite heterojunction is as follows:

[0123] S23: Bismuth nitrate and ferric nitrate were dispersed in a 1.5M nitric acid solution to obtain a mixed salt solution, wherein the molar ratio of bismuth nitrate to ferric nitrate was 1.05:1. This solution was added dropwise to an 8M potassium hydroxide solution until the pH reached 13 to obtain a suspension. The suspension was hydrothermally reacted at 240℃ for 48 hours. After centrifugation, the precipitate was washed alternately with 0.5M secondary nitric acid and deionized water, and then washed with water until the pH of the supernatant reached 7.1. The precipitate was dried to obtain bismuth ferrite particles. The bismuth ferrite particles were dispersed in ethylene glycol, and bismuth nitrate and polyvinylpyrrolidone were added to obtain reaction solution D, wherein the mass ratio of bismuth ferrite particles to bismuth nitrate was 1:8, and the mass ratio of polyvinylpyrrolidone to bismuth nitrate was 1:1. After stirring continuously for 60 minutes, a potassium iodide solution in ethylene glycol was added dropwise to obtain reaction solution E, wherein the molar ratio of potassium iodide to bismuth nitrate was 1.2:1. The mixture was stirred at 60℃ for 5 hours, centrifuged, washed, and dried to obtain a bismuth iodide oxide / bismuth ferrite heterojunction.

[0124] Comparative Example 1

[0125] This comparative example provides a negative ion-releasing activated carbon composite purification material. The difference between this example and Example 1 is that no hydrophilic core-shell structured upconversion nanoparticle dispersion is added. Other operating steps and process parameters are exactly the same as in Example 1.

[0126] Comparative Example 2

[0127] This comparative example provides a negative ion releasing activated carbon composite purification material. The difference from Example 1 is that the S22 shell coating step is omitted, and the core nanoparticles are directly used for hydrophilization and loading steps. Other operation steps and process parameters are exactly the same as in Example 1.

[0128] Comparative Example 3

[0129] This comparative example provides a negative ion-releasing activated carbon composite purification material. The difference from Example 1 is that bismuth ferrite particles and bismuth oxyiodide are prepared separately and mixed in the same mass ratio. Other operating steps and process parameters are exactly the same as in Example 1.

[0130] Comparative Example 4

[0131] This comparative example provides a negative ion-releasing activated carbon composite purification material. The difference between this example and Example 1 is that no bismuth oxyiodide / bismuth ferrite heterojunction is added. All other operating steps and process parameters are exactly the same as in Example 1.

[0132] The performance of the negative ion-releasing activated carbon composite purification materials prepared in Examples 1-4 and Comparative Examples 1-4 was tested, and the specific process is as follows:

[0133] Gaseous pollutant degradation performance test: A composite purification material sample was placed in a sealed quartz glass reactor equipped with a built-in fan, and a quantitative concentration of the target pollutant (such as formaldehyde) was injected. The reactor was then allowed to stand in the dark and without wind for 1 hour to reach adsorption equilibrium. Subsequently, the reaction was carried out for 2 hours under constant temperature and humidity conditions and different conditions ("near-infrared light + airflow disturbance", "near-infrared light only", or "airflow disturbance only"). After the reaction, a sample was taken from the reactor, and the final pollutant concentration was measured using a gas chromatograph to calculate the degradation rate.

[0134] The test results are shown in Table 1.

[0135] Table 1 Performance test results of negative ion releasing activated carbon composite purification materials prepared in Examples 1-4 and Comparative Examples 1-4

[0136]

[0137] As shown in Table 1, the test results of Example 1 and Comparative Example 1 reveal that the absence of a hydrophilic core-shell upconversion nanoparticle dispersion leads to a sharp decline in the catalytic performance of the composite material under near-infrared light irradiation. This is because the lack of core-shell upconversion nanoparticles capable of converting near-infrared light into high-energy ultraviolet / blue light prevents the subsequent bismuth oxyiodide / bismuth ferrite heterojunction from being effectively excited to generate photogenerated charges. Under the conditions of "near-infrared light + airflow disturbance," the degradation rate is essentially the same as that under the condition of "airflow disturbance only," indicating that the catalytic activity at this point almost entirely originates from the piezoelectric effect of bismuth ferrite, while near-infrared light cannot provide any additional photocatalytic contribution.

[0138] As shown in Table 1, the test results of Example 1 and Comparative Example 2 reveal that omitting the S22 shell coating step and directly using core nanoparticles for hydrophilization and loading significantly reduces degradation ability under all conditions including near-infrared irradiation. This is because the upconversion luminescence efficiency of core nanoparticles is much lower than that of core-shell structured particles that have undergone "surface passivation" with an inert shell due to the surface quenching effect. Consequently, the number of internal photons provided to subsequent catalytic units is greatly reduced, and the amount of photogenerated charge also decreases, ultimately leading to a decline in overall catalytic activity. However, the performance under conditions of airflow disturbance is relatively minor.

[0139] As shown in Table 1, the test results of Example 1 and Comparative Example 3 reveal that mixing bismuth ferrite particles and bismuth oxyiodide at the same mass ratio significantly weakens the enhancing effect of piezoelectricity on photocatalytic performance. Under near-infrared light + airflow disturbance conditions, the degradation performance of the material decreases because the physically mixed particles lack atomically tight interfaces, preventing the piezoelectric potential field from effectively acting on the photogenerated charge, and the synergistic effect of piezo-photoelectronics almost completely fails.

[0140] As shown in Table 1, the test results of Example 1 and Comparative Example 4 reveal that without the addition of the bismuth oxyiodide / bismuth ferrite heterojunction, the material almost completely loses its chemical catalytic degradation ability. Under all test conditions, its pollutant removal efficiency decreased. This is because the bismuth oxyiodide / bismuth ferrite heterojunction is the core execution unit of the entire energy conversion and catalytic reaction chain. Removing this component is equivalent to cutting off the entire pathway from energy input to chemical degradation; even if the core-shell upconversion nanoparticles can emit light normally, the system cannot utilize this energy for catalytic reactions.

[0141] The above description is only a specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Those skilled in the art should understand that any changes or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention fall within the protection and disclosure scope of the present invention.

Claims

1. A method for preparing a negative ion-releasing activated carbon composite purification material, characterized in that, The preparation method includes: S1: Prepare graphene oxide dispersion, add mesoporous activated carbon powder and urea to obtain a mixture; treat the mixture with ultrasound to obtain a reaction precursor solution, perform hydrothermal reaction, cool naturally after the reaction is completed, take out the hydrogel, wash and pre-freeze, and then freeze-dry to obtain nitrogen-doped graphene / activated carbon aerogel substrate. S2: Hydrophobic core-shell upconversion nanoparticles are dispersed in chloroform to obtain a dispersion. An equal volume of sodium citrate solution is added to the dispersion, and the pH is adjusted to obtain a treatment solution. The treatment solution is ultrasonically emulsified, allowed to stand and separate into phases, the upper aqueous phase is collected, centrifuged, washed, and the product is dispersed in deionized water to obtain a hydrophilic core-shell upconversion nanoparticle dispersion. A nitrogen-doped graphene / activated carbon aerogel substrate is impregnated in an ethanol dispersion of bismuth oxyiodide / bismuth ferrite heterojunction to obtain a reaction solution F. After ultrasonic treatment at room temperature, it is dried to obtain an aerogel intermediate loaded with heterojunction. The aerogel intermediate loaded with heterojunction is impregnated in a hydrophilic core-shell upconversion nanoparticle dispersion to obtain a reaction solution G. After ultrasonic treatment, the composite gel is freeze-dried to obtain a negative ion releasing activated carbon composite purification material.

2. The preparation method of a negative ion releasing activated carbon composite purification material according to claim 1, characterized in that, In S1: The mass ratio of the graphene oxide, mesoporous activated carbon powder and urea is 1:(0.5-1.5):(20-40).

3. The preparation method of a negative ion releasing activated carbon composite purification material according to claim 1, characterized in that, In S2: The mass ratio of the nitrogen-doped graphene / activated carbon aerogel substrate to the bismuth oxyiodide / bismuth ferrite heterojunction is 10:(1-3); The mass ratio of the aerogel intermediate loaded with heterostructure to the hydrophilic core-shell upconversion nanoparticles is 100:(2-5).

4. The preparation method of a negative ion releasing activated carbon composite purification material according to claim 1, characterized in that, In S2, the preparation method of hydrophobic core-shell structured upconversion nanoparticles is as follows: S21: Rare earth acetate is added to a mixed solvent to obtain a mixed dispersion. The mixed dispersion is heated under argon protection and then stirred under vacuum to obtain a rare earth oleate precursor solution. The solution is cooled and a methanol solution of sodium hydroxide and a methanol solution of ammonium fluoride are added to obtain reaction solution A. After stirring, the temperature is raised to evaporate the methanol and then the temperature is raised again to react. After cooling, an oil phase dispersion of core nanoparticles is obtained. The rare earth acetate is yttrium acetate, ytterbium acetate and thulium acetate. S22: Yttrium acetate was dispersed in a mixed solvent to obtain a shell precursor solution. After heating under argon protection, the solution was stirred under vacuum to obtain a yttrium oleate precursor solution. After cooling, the solution was added to the oil phase dispersion of the core nanoparticles to obtain reaction solution B. The reaction solution B was added to a methanol solution of sodium hydroxide and a methanol solution of ammonium fluoride to obtain reaction solution C. After stirring, the methanol was evaporated and the reaction was carried out at a higher temperature. After cooling to room temperature, anhydrous ethanol was added to break the emulsion. The solution was centrifuged, washed, and dried to obtain hydrophobic core-shell upconversion nanoparticles.

5. The preparation method of a negative ion releasing activated carbon composite purification material according to claim 4, characterized in that, In S21: The molar ratio of yttrium acetate, ytterbium acetate, and thulium acetate in the mixed dispersion is (78-80):(20-22):(0.2-0.5); The mixed solvent is a mixture of oleic acid and 1-octadecene, wherein the volume ratio of oleic acid to 1-octadecene is 1:(1-1.5); The ratio of the total molar amount of rare earth acetate to the volume of 1-octadecene is 1 mmol:(10-20) mL.

6. The preparation method of a negative ion releasing activated carbon composite purification material according to claim 4, characterized in that, In S21: The molar ratio of sodium hydroxide to rare earth acetate in reaction solution A is (2-3):

1. The molar ratio of ammonium fluoride to rare earth acetate in the reaction solution A is (3.5-4.5):

1.

7. The preparation method of a negative ion releasing activated carbon composite purification material according to claim 4, characterized in that, In S22: The mixed solvent is a mixture of oleic acid and 1-octadecene, wherein the volume ratio of oleic acid to 1-octadecene is 1:(1-1.5); The molar amount of yttrium acetate to the volume ratio of 1-octadecene in the shell precursor solution is 1 mmol:(5-10) mL; The molar ratio of yttrium acetate in the shell precursor solution to the total molar amount of rare earth acetate in the mixed dispersion described in S21 is (0.3-0.6):1; The molar ratio of sodium hydroxide to yttrium acetate in the shell precursor solution is (2-3):1; The molar ratio of ammonium fluoride to yttrium acetate in the shell precursor solution is (3.5-4.5):

1.

8. The preparation method of a negative ion releasing activated carbon composite purification material according to claim 1, characterized in that, In S2, the preparation method of the bismuth oxyiodide / bismuth ferrite heterojunction is as follows: S23: Bismuth nitrate and ferric nitrate are dispersed in nitric acid solution to obtain a mixed salt solution. The mixed salt solution is added dropwise to potassium hydroxide solution to obtain a suspension. The suspension is subjected to hydrothermal reaction, centrifuged, and the precipitate is washed alternately with second nitric acid and deionized water. The precipitate is then washed with water until the pH of the supernatant is 7.0-7.

2. The precipitate is dried to obtain bismuth ferrite particles. The bismuth ferrite particles are dispersed in ethylene glycol, and bismuth nitrate and polyvinylpyrrolidone are added to obtain reaction solution D. After continuous stirring, potassium iodide in ethylene glycol solution is added dropwise to obtain reaction solution E. The mixture is stirred, centrifuged, washed, and dried to obtain bismuth iodide oxide / bismuth ferrite heterojunction.

9. The preparation method of a negative ion releasing activated carbon composite purification material according to claim 8, characterized in that, In S23: The molar ratio of bismuth nitrate to ferric nitrate in the mixed salt solution is (1-1.05):1; The mass ratio of bismuth ferrite particles to bismuth nitrate particles in the reaction solution D is 1:(4-8); The mass ratio of polyvinylpyrrolidone to bismuth nitrate in the reaction solution D is (0.5-1):1; The molar ratio of potassium iodide to bismuth nitrate in the reaction solution E is (1-1.2):

1.

10. A negative ion-releasing activated carbon composite purification material prepared by the preparation method according to any one of claims 1-9.

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