Preparation method of catalyst and catalyst

Abstract

The invention relates to the field of photocatalytic degradation, and provides a preparation method of a catalyst and the catalyst.The preparation method comprises the following steps that firstly, TiN nanoparticles are subjected to light irradiation oxidation, and a TiN / TiO2 catalyst is prepared; and 2, carrying out reduction treatment on the TiN / TiO2 catalyst in a NaBH4 aqueous solution, introducing oxygen vacancies to the surface of the TiN / TiO2 catalyst, and carrying out centrifugation and drying to obtain the TiN / TiO2-Ov catalyst. Therefore, the catalytic performance of the catalyst on antibiotics can be further improved.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of photocatalytic degradation, and particularly relates to a preparation method of a catalyst capable of improving the catalytic performance on antibiotics and the catalyst. BACKGROUND

[0002] As a key drug in the fields of medical treatment and breeding, antibiotics are difficult to be completely metabolized by organisms, and a large amount of antibiotics are excreted into the water cycle system with feces and urine. Residues of various antibiotics such as β-lactams, tetracyclines, fluoroquinolones and sulfonamides have been detected in surface water, groundwater and drinking water sources. These residues not only destroy the ecological balance of water (such as inhibiting the photosynthesis of algae and interfering with the physiological functions of fish), but also accumulate through the food chain, induce bacteria to produce drug-resistant genes, and pose a potential threat to human health. The persistence of antibiotics in sewage has become an urgent environmental pressure source to be solved.

[0003] Existing technical means for treating antibiotics have limitations: the microbial degradation method has strict requirements on environmental temperature, pH value and other conditions, and the degradation rate of structurally stable antibiotics is slow; the chemical oxidation method can quickly decompose pollutants, but consumes a large amount of oxidizing agents, and the energy consumption and treatment cost are high; the physical separation method (such as membrane filtration) has low interception efficiency for low-concentration antibiotics, and the running cost is prone to skyrocketing due to membrane pollution; the adsorption method is limited by the selectivity of the adsorbent, and has poor removal effect on low-concentration antibiotics, and has problems such as narrow PH application range and difficult regeneration of adsorbent.

[0004] Photocatalytic technology can mineralize antibiotics into harmless CO2, H2 and inorganic ions by virtue of the strong oxidation ability of reactive oxygen species (such as hydroxyl radical OH, superoxide radical O2 - ) generated by photocatalysts under light, and has great potential in the field of degrading pollutants. At present, TiO2 is widely used due to its high chemical stability and low cost, but it is limited by the wide band gap of 3.2eV, and can only respond to ultraviolet light (about 7% of sunlight), the light utilization rate is low, and the recombination rate of photo-generated electron-hole pairs is high, which restricts the catalytic efficiency.

[0005] Therefore, in the prior art, how to improve the catalytic performance of the catalyst on antibiotics has become a technical problem. SUMMARY

[0006] The application aims to provide a catalyst preparation method and a catalyst capable of improving the catalytic performance of the catalyst on antibiotics. To achieve the above-mentioned purpose, one scheme of the application is a catalyst preparation method, comprising the following steps: step one: oxidizing TiN nanoparticles by light irradiation to obtain a TiN / TiO2 catalyst; and step two: reducing the TiN / TiO2 catalyst in a NaBH4 aqueous solution, introducing oxygen vacancies on the surface of the TiN / TiO2 catalyst, and then obtaining a TiN / TiO2-O v catalyst.

[0007] In a preferred mode, in the step one, the light irradiation intensity is 2200-2400 mW / cm 2 .

[0008] In a preferred mode, in the step one, the light irradiation time is 10-13 s.

[0009] In a preferred mode, in the step two, the concentration of the NaBH4 aqueous solution is 0.4-0.6 mol / L.

[0010] In a preferred mode, the TiN / TiO2 catalyst is reduced in the NaBH4 aqueous solution for 3-3.5 h.

[0011] In a preferred mode, the TiN / TiO2 catalyst is reduced in the NaBH4 aqueous solution at a temperature of 40-60℃.

[0012] In a preferred mode, in the step two, the drying temperature is 60-100℃.

[0013] In a preferred mode, in the step two, the drying time is 6-12 h.

[0014] In addition, another aspect of the application is a catalyst prepared by the aforementioned catalyst preparation method; wherein the catalyst has TiO2-O v as an active center and TiN as a light-heat conversion center.

[0015] According to the aforementioned technical scheme, the light absorption capacity of the catalyst prepared by the application is significantly improved, and the reduction in the NaBH4 aqueous solution to construct oxygen vacancies also helps to enhance the adsorption and activation effect of the catalyst on antibiotic molecules. BRIEF DESCRIPTION OF DRAWINGS

[0016] In order to more clearly illustrate the present application, a description and illustration of the drawings of the present application will be described and explained below. Obviously, the drawings described below in the description only illustrate some aspects of the exemplary embodiments of the present application, and other drawings can also be obtained by those of ordinary skill in the art without creative labor on the basis of these drawings.

[0017] Figure 1 is an X-ray diffraction pattern of Example 1.

[0018] Figure 2 is an EDS energy spectrum pattern of Example 1.

[0019] Figure 3 is a performance graph of photocatalytic degradation of tetracycline of Example 1-Example 4 at an antibiotic concentration of 50 mg / L.

[0020] Figure 4 is a performance graph of photocatalytic degradation of tetracycline of Example 1 and Example 5-Example 8 at an antibiotic concentration of 50 mg / L.

[0021] Figure 5 is a cycle performance graph of photocatalytic degradation of tetracycline of Example 1.

[0022] Figure 6 is a performance graph of photocatalytic degradation of tetracycline of Example 1 and Comparative Example 1 at an antibiotic concentration of 50 mg / L. DETAILED DESCRIPTION

[0023] Various exemplary embodiments of the present application are described in detail below with reference to the attached drawings. The description of the exemplary embodiments is merely illustrative, and in no way limits the present application, its application or uses. The present application can be implemented in numerous different forms, and is not limited to the embodiments described herein. These embodiments are provided so that this disclosure will be thorough and complete, and fully convey the scope of the application to those skilled in the art. It should be noted that the relative arrangement of the components and steps illustrated in these embodiments, numerical expressions, and numerical values, etc. set forth in these embodiments should be interpreted as merely exemplary, and not as a limitation of the application unless otherwise specified.

[0024] The "include" or "contain" and similar words used in the present application mean that the elements before the word cover the elements listed after the word, and do not exclude the possibility of also covering other elements.

[0025] All terms used in this application (including technical or scientific terms) have the same meaning as understood by one of ordinary skill in the art to which this application pertains, unless otherwise specifically defined. It should also be understood that terms defined in general dictionaries should be interpreted as having meanings consistent with their meanings in the context of the relevant art, and not as being interpreted with idealized or highly formalized meanings, unless explicitly defined herein.

[0026] For components, specific model numbers and other parameters of components not described in detail in this section, the interrelationships between components and control circuits, these may be considered as techniques, methods and devices known to those skilled in the art, but where appropriate, such techniques, methods and devices should be considered part of the specification.

[0027] It should be noted that although the operations of the method described in this application are given a specific order, this does not require or imply that these operations must be performed in that specific order, or that all of the operations shown must be performed to achieve the desired result. On the contrary, the steps described in this application may be performed in a different order. Additionally or alternatively, certain steps may be omitted, multiple steps may be combined into one step, and / or one step may be broken down into multiple steps.

[0028] The catalyst and its preparation method described in this application are explained in detail below.

[0029] The catalyst in this application is TiO2-O v TiN serves as the active center, a photothermal conversion center, and is commonly used in the photocatalytic degradation of antibiotics. Here, the active center refers to the specific atoms, atomic groups, or microstructures on the catalyst surface and / or inside that can adsorb reactant molecules and promote their chemical reaction. Simply put, it is the "core working region" of the catalyst. Furthermore, exemplarily, the water used in the experiments in this application is ultrapure water, and the purchased reagents are all analytical grade.

[0030] The preparation steps of the catalyst in this application are as follows: Step 1: TiN nanoparticles are oxidized by light irradiation to prepare TiN / TiO2 catalyst; Step 2: The TiN / TiO2 catalyst is reduced in NaBH4 aqueous solution to introduce oxygen vacancies on the surface of the TiN / TiO2 catalyst. After centrifugation and drying, TiN / TiO2-O is obtained. v catalyst.

[0031] As an example, in step one, commercial TiN nanoparticles are uniformly spread, for example, on glass, and oxidized by strong light to obtain a TiN / TiO2 catalyst.

[0032] For example, in step two, one oxygen atom is removed from the two oxygen atoms of a portion of the TiO2 molecules in all TiN / TiO2, thereby creating a corresponding number of oxygen vacancies. The reason for using O here is... v The term "oxygen vacancy" is used because not every TiO2 molecule is stripped of an oxygen atom. Rather, a portion of the many TiO2 molecules have an oxygen atom removed to form the corresponding oxygen vacancy. Therefore, it is neither necessary nor easy to accurately determine the total number of oxygen vacancies formed.

[0033] Light intensity determines the surface temperature of TiN, which in turn determines whether it can transform into TiO2. Both light intensity and irradiation time jointly determine the conversion ratio from TiN to TiO2 and the distribution of TiO2 crystal forms. It is well known that the TiO2 crystal form plays a crucial role in catalytic reactions; appropriately retained TiN can increase the temperature of the catalytic reaction and enhance catalytic activity. Furthermore, TiN can form heterojunctions with TiO2, further suppressing carrier recombination.

[0034] In this application, after in-situ oxidation and NaBH4 reduction treatment, TiN / TiO2-O v The composite material retains its nanosphere morphology, highly consistent with that of the original commercial TiN nanoparticles. This indicates that the strong photo-oxidation and mild reduction processes did not damage the original TiN framework structure: the nanosphere morphology not only ensures a large specific surface area, providing more catalytically active sites, but also the intact spherical structure facilitates light scattering and absorption, reducing photon energy loss and laying the structural foundation for full-spectrum photoresponse capability.

[0035] This application is based on extensive experiments to explore the optimal conditions for light intensity, light exposure time, NaBH4 aqueous solution concentration, and reduction time.

[0036] Experimental conditions: tetracycline concentration 50 mg / L, catalyst dosage 0.5 g / L, illumination conditions: natural light or 500 W xenon lamp, 2 mL sample, centrifugation, and supernatant were collected and the antibiotic concentration in the solution was detected using a UV spectrophotometer at a wavelength of 355 nm.

[0037] Experimental Data 1: Only the irradiation light intensity was adjusted, while other preparation parameters remained unchanged:

[0038] Based on existing experience, the light intensity needs to be higher than 2000 mW / cm². 2 Only under specific light intensity conditions can the transformation of TiN to TiO2 be effectively promoted. This light intensity is a crucial basis for conducting subsequent experiments. Therefore, we selected a light intensity of 1500-3000 mW / cm². 2Catalysts were synthesized within a certain range, and the performance of the catalysts obtained under various synthesis conditions was evaluated.

[0039] The performance evaluation results clearly show that when the light intensity is higher than 2000 mW / cm², 2 At this time, the degradation rate of tetracycline increased significantly, especially at 2200 mW / cm². 2 Under suitable light intensity, the degradation effect was particularly outstanding, achieving a tetracycline degradation rate of 98%. This result is closely related to the effective conversion of TiN to TiO2—when the light intensity is within this suitable range, TiN can be well converted into TiO2, providing sufficient target active centers for the catalytic reaction.

[0040] However, the catalytic effect will significantly decline when the light intensity is unsuitable. On the one hand, if the light intensity is too low (e.g., below 2000 mW / cm²), the catalytic effect will decrease. 2 When the TiN surface cannot reach a sufficient temperature, it is difficult to achieve an effective transformation to TiO2. At this time, the majority of the catalyst is still TiN, with almost no target active center TiO2, so it cannot effectively degrade tetracycline. On the other hand, if the light intensity is too high and exceeds the appropriate range, the crystal form of TiO2 is easily transformed into the rutile phase. The single rutile phase is not conducive to the catalytic reaction, thus affecting the degradation effect of tetracycline.

[0041] Therefore, preferably, in step one, the light intensity is 2200-2400 mW / cm². 2 This ensures a tetracycline degradation rate of over 95%.

[0042] Experimental Data 2: Only the irradiation time was adjusted, while other preparation parameters remained unchanged:

[0043] The experimental results show that changes in illumination time have a relatively limited impact on the degradation efficiency of tetracycline. This phenomenon can be analyzed in conjunction with the relationship between preparation conditions and catalyst characteristics: once the light intensity is determined, the temperature on the catalyst surface no longer fluctuates significantly, and the proportion of TiN to TiO2 is essentially fixed.

[0044] Under these circumstances, changes in irradiation time primarily affect the catalytic process by influencing the crystal structure of TiO2. Specifically, with prolonged irradiation time, the proportion of the thermodynamically more stable rutile phase in TiO2 gradually increases, while the proportion of the more catalytically active anatase phase decreases accordingly. Since a single rutile phase lacks sufficient surface active sites and a suitable band structure, it is difficult to efficiently adsorb and activate tetracycline molecules, nor can it effectively promote the separation and migration of photogenerated charges. Therefore, it adversely affects the smooth progress of the catalytic reaction, which is the key reason why irradiation time has a relatively small impact on degradation efficiency but still needs to be reasonably controlled.

[0045] Therefore, preferably, the light irradiation time is 10-13 seconds to ensure a tetracycline degradation rate of over 95%.

[0046] Experimental data 3: Only the concentration of the NaBH4 aqueous solution was adjusted, while other preparation parameters remained unchanged.

[0047] It can be seen that the concentration of NaBH4 aqueous solution is a key parameter for regulating the surface properties of the catalyst. Both excessively concentrated and excessively diluted NaBH4 solutions will have a significant adverse effect on the photodegradation process of tetracycline. From the perspective of the mechanism of action, an appropriate concentration of NaBH4 can construct reasonable defect structures or active sites on the catalyst surface through moderate reduction, while maintaining the integrity of its crystal structure. This ensures the effective separation of photogenerated charges without destroying the surface active centers required for the catalytic reaction.

[0048] When the NaBH4 aqueous solution is too dilute, its reducing effect is insufficient. At this point, it is difficult to form enough effective defects or active sites on the catalyst surface, failing to effectively promote the separation and migration of photogenerated charges, thus hindering the full activation of the catalyst's intrinsic catalytic activity. Simultaneously, the weak reducing effect may not improve the hydrophilicity / hydrophobicity or charge distribution on the catalyst surface, resulting in weak adsorption of tetracycline molecules, which in turn limits the subsequent photocatalytic degradation rate, ultimately leading to a low overall degradation efficiency.

[0049] If the NaBH4 aqueous solution is too concentrated, the excessive reducing substances will cause over-reduction on the catalyst surface. This may not only lead to the deep reduction of the active components on the catalyst surface or even the precipitation of elemental substances, destroying the original phase structure, but also cause excessive accumulation of surface defects, which will become recombination centers for photogenerated charges, significantly reducing charge separation efficiency.

[0050] It can be seen that when the concentration of NaBH4 aqueous solution is 0.4-0.6 mol / L, the tetracycline removal rate can reach more than 95%.

[0051] Experimental Data 4: Only the reduction time was adjusted, while other preparation parameters remained unchanged:

[0052] It can be seen that reduction time is equally crucial for regulating catalytic activity. An appropriate reduction time allows for the formation of a stable active structure on the catalyst surface: sufficient to generate the desired defects and active sites, while avoiding excessive reduction that damages the structure. If the reduction time is too short, surface reduction is insufficient, resulting in an inadequate number of active sites and hindering the intrinsic activity of the catalyst, thus limiting the tetracycline degradation efficiency. Conversely, an excessively long reduction time can easily lead to over-reduction, causing the structure of the active component to be destroyed. This not only reduces the effective active sites but may also enhance photogenerated charge recombination, thereby weakening the catalytic performance.

[0053] Therefore, preferably, the TiN / TiO2 catalyst is reduced in NaBH4 aqueous solution for 3-3.5 hours to ensure a tetracycline degradation rate of over 95%.

[0054] More preferably, the reduction treatment temperature of the TiN / TiO2 catalyst in NaBH4 aqueous solution is 40–60 °C.

[0055] More preferably, in step two, the drying temperature is 60-100℃ and the drying time is 6-12h.

[0056] Next, the catalyst and its preparation method of this application will be further described with reference to examples and comparative examples.

[0057] Example 1

[0058] (1) Weigh 75 mg of commercial TiN nanoparticles and spread them evenly on a clean glass surface, ensuring that there is no obvious accumulation of particles. Use a Fresnel lens with a diameter of 10 cm to focus strong light and irradiate the spread TiN particles. The irradiation time is controlled to be 10 s to complete the oxidation treatment and obtain TiN / TiO2 catalyst.

[0059] (2) Prepare a 0.5 mol / L NaBH4 aqueous solution, and place the TiN / TiO2 catalyst obtained in step (1) into the aqueous solution. Reduce the catalyst at 40°C for 3 hours. After treatment, obtain TiN / TiO2-O by centrifugation, washing with deionized water three times, and vacuum drying. v Heterogeneous junction.

[0060] Example 2

[0061] (1) Weigh 75 mg of commercial TiN nanoparticles and spread them evenly on a clean glass surface, ensuring that there is no obvious accumulation of particles. Use a Fresnel lens with a diameter of 10 cm to focus strong light and irradiate the spread TiN particles. Control the irradiation time to 5 s to complete the oxidation treatment and obtain TiN / TiO2 catalyst.

[0062] (2) Prepare a 0.5 mol / L NaBH4 aqueous solution, and place the TiN / TiO2 catalyst obtained in step (1) into the aqueous solution. Reduce the catalyst at 40°C for 3 hours. After treatment, obtain TiN / TiO2-O by centrifugation, washing with deionized water three times, and vacuum drying. v Heterogeneous junction.

[0063] Example 3

[0064] (1) Weigh 75 mg of commercial TiN nanoparticles and spread them evenly on a clean glass surface, ensuring that there is no obvious accumulation of particles. Use a Fresnel lens with a diameter of 10 cm to focus strong light and irradiate the spread TiN particles. The irradiation time is controlled to be 13 s to complete the oxidation treatment and obtain TiN / TiO2 catalyst.

[0065] (2) Prepare a 0.5 mol / L NaBH4 aqueous solution, and place the TiN / TiO2 catalyst obtained in step (1) into the aqueous solution. Reduce the catalyst at 40°C for 3 hours. After treatment, obtain TiN / TiO2-O by centrifugation, washing with deionized water three times, and vacuum drying. v Heterogeneous junction.

[0066] Example 4

[0067] (1) Weigh 75mg of commercial TiN nanoparticles and spread them evenly on a clean glass surface, ensuring that there is no obvious accumulation of particles. Use a Fresnel lens with a diameter of 10cm to focus strong light and irradiate the spread TiN particles. The irradiation time is controlled to be 20s to complete the oxidation treatment and obtain TiN / TiO2 catalyst.

[0068] (2) Prepare a 0.5 mol / L NaBH4 aqueous solution, and place the TiN / TiO2 catalyst obtained in step (1) into the aqueous solution. Reduce the catalyst at 40°C for 3 hours. After treatment, obtain TiN / TiO2-O by centrifugation, washing with deionized water three times, and vacuum drying. v Heterogeneous junction.

[0069] Example 5

[0070] (1) Weigh 75 mg of commercial TiN nanoparticles and spread them evenly on a clean glass surface, ensuring that there is no obvious accumulation of particles. Use a Fresnel lens with a diameter of 10 cm to focus strong light and irradiate the spread TiN particles. The irradiation time is controlled to be 10 s to complete the oxidation treatment and obtain TiN / TiO2 catalyst.

[0071] (2) Prepare a 0.1 mol / L NaBH4 aqueous solution, and place the TiN / TiO2 catalyst obtained in step (1) into the aqueous solution. Reduce the catalyst at 40°C for 3 hours. After treatment, obtain TiN / TiO2-O by centrifugation, washing with deionized water three times, and vacuum drying. v Heterogeneous junction.

[0072] Example 6

[0073] (1) Weigh 75 mg of commercial TiN nanoparticles and spread them evenly on a clean glass surface, ensuring that there is no obvious accumulation of particles. Use a Fresnel lens with a diameter of 10 cm to focus strong light and irradiate the spread TiN particles. The irradiation time is controlled to be 10 s to complete the oxidation treatment and obtain TiN / TiO2 catalyst.

[0074] (2) Prepare a 1 mol / L NaBH4 aqueous solution, and place the TiN / TiO2 catalyst obtained in step (1) into the aqueous solution. Reduce the catalyst at 40°C for 3 hours. After treatment, obtain TiN / TiO2-O by centrifugation, washing with deionized water three times, and vacuum drying. v Heterogeneous junction.

[0075] Example 7

[0076] (1) Weigh 75 mg of commercial TiN nanoparticles and spread them evenly on a clean glass surface, ensuring that there is no obvious accumulation of particles. Use a Fresnel lens with a diameter of 10 cm to focus strong light and irradiate the spread TiN particles. The irradiation time is controlled to be 10 s to complete the oxidation treatment and obtain TiN / TiO2 catalyst.

[0077] (2) Prepare a 0.5 mol / L NaBH4 aqueous solution, and place the TiN / TiO2 catalyst obtained in step (1) into the aqueous solution. Reduce the catalyst at 40°C for 1 hour. After treatment, obtain TiN / TiO2-O by centrifugation, washing with deionized water three times, and vacuum drying. v Heterogeneous junction.

[0078] Example 8

[0079] (1) Weigh 75 mg of commercial TiN nanoparticles and spread them evenly on a clean glass surface, ensuring that there is no obvious accumulation of particles. Use a Fresnel lens with a diameter of 10 cm to focus strong light and irradiate the spread TiN particles. The irradiation time is controlled to be 10 s to complete the oxidation treatment and obtain TiN / TiO2 catalyst.

[0080] (2) Prepare a 0.5 mol / L NaBH4 aqueous solution, and place the TiN / TiO2 catalyst obtained in step (1) into the aqueous solution. Reduce the catalyst at 40°C for 6 hours. After treatment, obtain TiN / TiO2-O by centrifugation, washing with deionized water three times, and vacuum drying. v Heterogeneous junction.

[0081] Comparative Example 1 A 0.5 mol / L NaBH4 aqueous solution was prepared, and a commercially available TiO2 catalyst was added to this solution. Reduction treatment was carried out at 40°C for 3 hours. After treatment, TiO2-O was obtained by centrifugation, washing three times with deionized water, and vacuum drying. v .

[0082] like Figure 1 As shown, X-ray diffraction (XRD) analysis was performed on the sample prepared in Example 1. The results showed that after in-situ oxidation under strong light irradiation and reduction with NaBH4, the diffraction peaks of the product highly matched the characteristic peaks of anatase TiO2 and rutile TiO2, and the rutile phase diffraction peaks were more intense, indicating that TiO2 in the product existed in a mixed crystal form with rutile phase as the main component and anatase phase as the auxiliary component. It is worth noting that the characteristic diffraction peaks of TiN did not appear in the XRD pattern. This is related to the fact that most of TiN was converted into TiO2 during the oxidation process, and the remaining content was low and highly dispersed. Its low content did not provide sufficient response for the XRD detection sensitivity.

[0083] like Figure 2 As shown, scanning electron microscopy (SEM) characterization revealed that, after in-situ oxidation and NaBH4 reduction treatment, the TiN / TiO2-O prepared in Example 1... v The composite material retains its microstructure as nanospheres with a diameter of approximately 50-80 nm, highly consistent with the morphology of the original commercial TiN nanoparticles. This result indicates that the strong photo-oxidation and mild reduction processes did not destroy the original framework structure of TiN: the nanosphere morphology not only ensures a large specific surface area, providing more catalytic active sites, but also the intact spherical structure facilitates light scattering and absorption, reducing photon energy loss and laying the structural foundation for full-spectrum photoresponse capability.

[0084] Of all the embodiments, Example 1 (10s illumination time) showed the best activity. If the illumination time is too short, it is not enough to convert TiN into TiO2 in large quantities. TiN alone has poor ability to degrade tetracycline. If the illumination time is too long, the crystal form of TiO2 will be completely converted into the rutile phase. A single crystal form is not conducive to the catalytic reaction.

[0085] Specifically, this is directly related to the evolution of TiO2 crystal forms: when the illumination time is too short (e.g., 5s in Example 2), TiN oxidation is incomplete, resulting in a small amount of TiO2, which mainly exists in amorphous or low-crystallinity form. At this time, the proportion of TiN in the system is relatively high, while pure TiN, lacking photocatalytic active centers (oxygen vacancies and heterojunction structures without TiO2), has a weak ability to degrade tetracycline (degradation rate of only 44% at 60 min). When the illumination time is too long (e.g., 20s in Example 4), TiN is almost completely oxidized to TiO2. Although the single rutile phase has high thermal stability, the photogenerated electron-hole pair recombination rate is fast, and the catalytic activity decreases significantly (degradation rate drops to 85% at 60 min). The 10s illumination condition in Example 1 allows for precise control of the TiO2 crystal form ratio while retaining an appropriate amount of TiN to form a heterojunction, thereby maximizing activity. Meanwhile, the 13s illumination condition in Example 3 is also within the preferred illumination time range of this application, therefore... Figure 3 The shown location also achieves better activity.

[0086] like Figure 4 As shown, by comparing the tetracycline degradation performance under different reduction conditions, the regulation of catalytic activity by the NaBH4 reduction parameters can be clearly identified: under the conditions of NaBH4 concentration of 0.5 mol / L, reduction temperature of 40℃, and reaction time of 3 h (Example 1), the catalyst achieved a 98% degradation rate of 50 mg / L tetracycline in 60 min. This optimal condition is directly related to the precise control of oxygen vacancy concentration. If the NaBH4 concentration is too low (e.g., 0.1 mol / L, Example 5), insufficient oxygen vacancy generation will result in a weak adsorption capacity of the catalyst for tetracycline; if the NaBH4 concentration is too high (e.g., 1 mol / L, Example 6), over-reduction will occur, forming a large number of disordered defects, which will instead become electron-hole recombination centers. Furthermore, if the reaction time in NaBH4 is too short (1 h, Example 7), the oxygen vacancy concentration will be insufficient; if the reaction time is too long (6 h, Example 8), TiO2-O2 may be triggered. v The partial collapse of the structure will reduce catalytic activity.

[0087] like Figure 5As shown, the cyclic stability test of the catalyst further verified its practical application potential: the catalyst of Example 1 was used for 6 cycles (after each use, it was separated by centrifugation at 10,000 rpm for 3 min, washed 3 times with deionized water, and regenerated by vacuum drying at 80℃ for 12 h), and its 60 min degradation rate of tetracycline remained above 97%, indicating that TiN / TiO2-O v The heterojunction structure has good chemical stability, and oxygen vacancies are not easily lost in the cyclic reaction, which provides a reliable guarantee for its long-term practical application.

[0088] Figure 6 This is a graph showing the photocatalytic degradation performance of tetracycline in Example 1 and Comparative Example 1 at an antibiotic concentration of 50 mg / L. Figure 6 As shown, under the condition that the NaBH4 reduction process parameters (including NaBH4 dosage, reduction temperature, reaction time, etc.) are completely consistent with those in Example 1, TiO2-O is prepared by direct single reduction treatment using commercial TiO2. v Its activity was still significantly lower than that of Example 1. Despite the same NaBH4 reduction conditions, commercial TiO2, after single reduction, could only form a certain amount of oxygen vacancies on the surface and lacked the synergistic effect of the TiN phase: on the one hand, without TiN as an electron-capturing center, photogenerated electron-hole pairs easily recombine, resulting in insufficient light absorption efficiency conversion and inability to effectively stimulate the active free radicals required for antibiotic degradation; on the other hand, the activity of commercial TiO2-O2 alone was significantly lower than that of Example 1. v The surface adsorption capacity is weak, and due to the crystal structure and surface state of commercial TiO2 itself, even under the same reduction conditions, it is impossible to form an efficient reaction cycle of "adsorption-activation-degradation".

[0089] In summary, this invention innovatively combines in-situ oxidation with NaBH4 reduction to successfully prepare TiN / TiO2-O with high oxygen vacancy content. v Heterogeneous structure. Experiments have verified that this synthesized TiN / TiO2-O... v Under full light conditions, the TiN / TiO2 composite catalyst exhibits excellent antibiotic degradation activity. Its heterojunction structure effectively promotes electron-hole separation, while TiN's narrow bandgap broadens the photoresponse range into the infrared region. Furthermore, TiN's excellent infrared absorption and high photothermal conversion efficiency further accelerate the activation and degradation of antibiotic molecules through thermal effects, significantly improving the degradation of various antibiotics.

[0090] Among these methods, introducing oxygen vacancies via NaBH4 reduction is simple and easy, and the concentration of oxygen vacancies on the catalyst surface can be precisely controlled by adjusting the reduction concentration, temperature, and time. Thanks to the presence of TiN, the light absorption capacity of the prepared catalyst is significantly improved; and the construction of oxygen vacancies helps to enhance the adsorption and activation effect of antibiotic molecules on the catalyst.

[0091] It should be understood that the specific embodiments described above are only used to explain this application, and the scope of protection of this application is not limited thereto. Any changes, substitutions, or combinations made by those skilled in the art within the scope of the technology disclosed in this application, based on the technical solution and inventive concept of this application, should be covered within the scope of protection of this application.

Claims

1. A method for preparing a catalyst, characterized in that, Includes the following steps: Step 1: TiN nanoparticles are oxidized by photo-irradiation to prepare TiN / TiO2 catalyst; Step 2: The TiN / TiO2 catalyst is reduced in NaBH4 aqueous solution to introduce oxygen vacancies on the surface of the TiN / TiO2 catalyst. After centrifugation and drying, TiN / TiO2-O is obtained. v catalyst.

2. The method for preparing the catalyst according to claim 1, characterized in that: In step one, the light intensity is 2200-2400 mW / cm². 2 .

3. The method for preparing the catalyst according to claim 2, characterized in that: In step one, the illumination time is 10-13 seconds.

4. The method for preparing the catalyst according to any one of claims 1-3, characterized in that: In step two, the concentration of the NaBH4 aqueous solution is 0.4-0.6 mol / L.

5. The method for preparing the catalyst according to claim 4, characterized in that: The TiN / TiO2 catalyst was reduced in the NaBH4 aqueous solution for 3-3.5 hours.

6. The method for preparing the catalyst according to claim 5, characterized in that: The TiN / TiO2 catalyst is reduced in the NaBH4 aqueous solution at a temperature of 40-60℃.

7. The method for preparing the catalyst according to claim 1, characterized in that: In step two, the drying temperature is 60-100℃.

8. The method for preparing the catalyst according to claim 7, characterized in that: In step two, the drying time is 6-12 hours.

9. A catalyst, characterized in that: Prepared by the method for preparing the catalyst according to any one of claims 1-8; The catalyst is TiO2-O v TiN serves as the active center and the photothermal conversion center.

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