A Cu x O / BNAD composite photocatalyst, preparation method and application thereof

Abstract

A Cu x The preparation method of O / BNAD composite photocatalyst adopts a soft template method. Porous h-BN (p-BNNS) is prepared by high-temperature calcination of the precursor. Under low-temperature conditions, a diazotization reaction is used to generate p-BNNS diazonium salt, which is then coupled with an aromatic amine to obtain a porous boron nitride azo compound (p-BNAD) covalently linked by -N=N-azo bonds. Finally, copper oxide / boron azo nitride (Cu) is prepared by vacuum impregnation with copper salt. x This invention utilizes an O / BNAD composite photocatalyst for the efficient reduction of Cr(VI) and the inhibition of bacteria. Under simulated sunlight, Cu... x O / BNAD can effectively reduce Cr(VI) ions, with an apparent kinetic constant of 0.071 min. ‑1 The conversion rate is as high as 88.67%. Under visible light irradiation, it can effectively inhibit the reproduction of Gram bacteria, with an antibacterial rate of 98.0-99.9%.

Description

Technical Field

[0001] This invention relates to a Cu x O / BNAD composite photocatalysts, their preparation methods and applications belong to the field of photocatalytic composite material technology. Background Technology

[0002] Against the backdrop of rapid industrial development, water pollution has become increasingly severe, posing a serious threat to human health. Hexavalent chromium [Cr(VI)] is highly toxic, carcinogenic, bioaccumulative, and highly water-soluble. It easily migrates through water and soil, accumulates in organisms after absorption, damages human organs, and disrupts ecological balance. Compared to Cr(VI), the reduction product trivalent chromium [Cr(III)] is only about 1 / 100th as toxic, has low water solubility, and easily forms hydroxide precipitates in the natural environment, facilitating subsequent separation and removal, thus reducing pollution risks at the source. Simultaneously, the proliferation of pathogenic bacteria in water bodies can trigger various diseases, threatening human health by releasing toxins and damaging cell tissues, as well as causing water pollution and exacerbating ecosystem dysfunction. Therefore, developing catalysts that can efficiently degrade Cr(VI) pollutants and also possess antibacterial properties is particularly important.

[0003] Photocatalysis, a cutting-edge green technology that utilizes solar energy to drive chemical reactions, has broad application prospects in the fields of pollutant degradation and antibacterial applications. This technology uses solar energy as its energy source, offering advantages such as low energy consumption and environmental friendliness. It can efficiently reduce highly toxic Cr(VI) to less toxic Cr(III), with a fast reaction rate and recyclable photocatalysts. Simultaneously, photocatalysis can convert harmful substances in organic waste gas and wastewater into harmless substances, and by releasing reactive oxygen species and metal ions, it can disrupt the cell walls and cell membranes of bacteria, achieving environmental purification and antibacterial effects. With continuous innovation and improvement of photocatalysts and related equipment, its reaction rate and stability have significantly improved, and production costs have gradually decreased, further enhancing the feasibility and application prospects of this technology.

[0004] Hexagonal boron nitride (h-BN), with its two-dimensional layered structure, not only exhibits excellent structural stability, high thermal conductivity, and good thermal stability, but also displays unique electrical and optical properties. This material has a large specific surface area and strong adsorption capacity, while also possessing environmental friendliness and good biocompatibility, demonstrating unique advantages in pollutant degradation and serving as an excellent carrier for metal oxides. Furthermore, due to its outstanding adsorption capacity and antibacterial properties, h-BN also shows broad prospects in antibacterial applications, demonstrating significant research value and enormous application potential.

[0005] Patent CN 115970730 A discloses a rare earth / sulfur co-doped boron nitride material and its preparation method. The method involves mixing and calcining boron acid, nitrogen-containing organic matter, and rare earth nitrates as raw materials to obtain rare earth-doped boron nitride. The rare earth-doped boron nitride is then activated by hydroxylation. Under a nitrogen protective atmosphere, a sulfur source and the activated rare earth-doped boron nitride are placed in a tube furnace and heated in stages to finally obtain the rare earth / sulfur co-doped boron nitride material. This material can efficiently photocatalytically degrade dye-like organic pollutants such as methyl orange and rhodamine B in water under visible light.

[0006] Patent CN 116273127 A discloses a preparation method and application of an N-ZnO / p-BN composite photocatalyst. The method uses melamine and boric acid as raw materials, which are stirred in a water bath, cooled, filtered, and dried to obtain a precursor. The precursor is then subjected to high-temperature pyrolysis under a nitrogen atmosphere to obtain porous boron nitride (p-BN) powder. The p-BN powder, zinc acetate dihydrate, and urea are then dispersed in anhydrous ethanol and stirred. After hydrothermal reaction, the mixture is centrifuged, washed, and dried to finally obtain the N-ZnO / p-BN composite photocatalyst. This catalyst can be used for the adsorption and photodegradation of antibiotic pollutants such as oxytetracycline, tetracycline, and ofloxacin in water.

[0007] Patent CN 113351238 A discloses a boron nitride-based material for photocatalytic degradation of perfluorinated compounds. The material uses boron nitride powder as raw material, which is acidified with nitric acid and ultrasonically dispersed in anhydrous ethanol to obtain a BN dispersion. Titanium tetrachloride, tetrabutyl titanate, and glacial acetic acid are then added dropwise and stirred. Next, magnetically activated magnetic shell energy storage microspheres are added and mixed and aged. Finally, the mixture is dried at low temperature, the microspheres are removed by magnetic separation, and it is ground and calcined to obtain a BN / TiO2 composite material. This boron nitride-based material (BN material, BN / TiO2 composite material, or a mixture of both) can efficiently photocatalytically degrade perfluorinated compounds such as potassium perfluorohexyl ethyl xanthate and ammonium hexafluoropropylene oxide dimer in water under 254 nm light irradiation.

[0008] The above studies confirm that h-BN has been widely used in the field of photocatalysis. It can serve as a carrier for photoactive substances and can also form stable heterostructures with other semiconductor materials to build high-performance photocatalytic composite materials. However, the h-BN matrix reported above only absorbs ultraviolet and limited visible light, and has almost no absorption for longer wavelength infrared light, which limits its application in various environments. Summary of the Invention

[0009] To overcome the shortcomings of existing technologies, this invention provides a Cu x O / BNAD composite photocatalysts, their preparation methods, and applications; copper oxide nanoparticles supported on boron azonitride to obtain copper oxide / boron azonitride (Cu) composites. xThe O / BNAD composite photocatalyst exhibits excellent photocatalytic performance and can efficiently inhibit bacterial growth while photocatalytically reducing Cr(VI) ions.

[0010] The technical solution adopted by this invention to solve its technical problem is: A Cu x A method for preparing O / BNAD composite photocatalysts, the method comprising the following steps: Step a, preparation of p-BNNS: Melamine, urea and boric acid are mixed and ball-milled to obtain h-BN precursor. The h-BN precursor and pore-forming agent are ground evenly and then calcined at high temperature in a tube furnace to obtain porous boron nitride nanosheets (p-BNNS). Step b, preparation of p-BNAD: ① Diazotization reaction: After diluting concentrated hydrochloric acid, add p-BNNS and place in an ice-water bath at 0~5 ℃; dissolve NaNO2 in deionized water and slowly add it dropwise to the above solution and stir to obtain solution A; ② Coupling reaction: The coupling agent is mixed with acetic acid and slowly added dropwise to solution A. Then, 5% NaOH aqueous solution is added to the mixture. After mixing evenly, the mixture is placed in a water bath at 60 °C for 6-7 min and kept warm for a long time. After cooling completely, the mixture is filtered and washed to finally obtain boron azonitride (p-BNAD). Step c, Cu x Preparation of O / BNAD: Weigh p-BNAD, a protective agent, and a certain mass of CuCl2 into a beaker, add deionized water, and impregnate under vacuum for 2 h. Adjust the pH to 9.0 by adding ammonia dropwise. Place this system in an 80 ℃ water bath and add a 40% NaOH aqueous solution dropwise until precipitation is complete. Then, dry the precipitate to constant weight and calcine at a certain temperature for 1 h to obtain CuCl2. x O / BNAD composite photocatalyst.

[0011] The above Cu x The preparation method of O / BNAD composite photocatalyst, in step a, the molar ratio of melamine, urea and boric acid is 1:0.3~0.6:1~3; the porogen is one of ammonium bicarbonate, magnesium sulfate or barium sulfate; the mass ratio of the h-BN precursor and the porogen is 5:5~8:2.

[0012] The above Cu x The preparation method of O / BNAD composite photocatalyst, in step a, the calcination temperature is 850 ℃, the calcination time is 4 h, and the calcination heating rate is 5 ℃ / min.

[0013] The above Cu xThe preparation method of O / BNAD composite photocatalyst, in step b, the concentration of concentrated hydrochloric acid after dilution is 20% (2 mL concentrated hydrochloric acid diluted to 10 mL), the volume-to-mass ratio of dilute hydrochloric acid to p-BNNS is 10 mL: 0.2 g; the concentration of the NaNO2 aqueous solution is 22~25 mg / mL.

[0014] The above Cu x The preparation method of O / BNAD composite photocatalyst, in step b, the coupling agent is one of N,N-dimethylaniline or other aromatic amine organic compounds, the volume ratio of the coupling agent to acetic acid is 1.54~2:1.54, the volume-to-mass ratio of the coupling agent to p-BNNS is 0.1~0.2mL:0.2~0.4g, and the volume ratio of 5% NaOH aqueous solution to solution A is 3~4:15.

[0015] The above Cu x The preparation method of O / BNAD composite photocatalyst, in step c, the protective agent is polyvinylpyrrolidone (PVP), the mass ratio of p-BNAD to the protective agent is 4:0.2~0.4, and the mass percentage of Cu element in CuCl2 to the mass of p-BNAD is 4.2 wt.%~10.0 wt.%.

[0016] The above Cu x The preparation method of O / BNAD composite photocatalyst, wherein in step c, the calcination temperature is 100~200 ℃.

[0017] A Cu x O / BNAD composite photocatalyst, Cu obtained by the preparation method described above. x O / BNAD composite photocatalyst, wherein Cu x O is a mixture of CuO and Cu2O.

[0018] A Cu x The application of O / BNAD composite photocatalysts, the Cu x O / BNAD composite photocatalysts are used to reduce Cr(VI) pollutants in water and inhibit the growth of Gram bacteria.

[0019] (1) Photocatalytic reduction of Cr(VI): The prepared composite photocatalyst was dispersed in a solution containing Cr(VI) pollutants and stirred in the dark for 0.5-1 h to ensure that the catalyst reached an adsorption-desorption equilibrium state; then, it was irradiated with a 300 W xenon lamp for 30 min to complete the reduction reaction; wherein, 10-20 mg of composite photocatalyst was added to every 40 mL of solution containing pollutants; the concentration of pollutants in the solution was 20-30 mg·L. -1The initial pH of the system was adjusted to be in the range of 2 to 4 using 1 mol / L HCl and NaOH solutions.

[0020] (2) Photocatalytic antibacterial activity: ① Bacterial suspension: Gram-positive and / or Gram-negative bacteria were selected as model bacteria, activated and cultured under suitable conditions to the logarithmic growth phase, and diluted to a predetermined concentration (1.0 × 10⁻⁶). 5 ~1.0×10 6 ① Mixing: The bacterial suspension and the composite photocatalyst are mixed at a certain mass ratio; ② Photocatalytic reaction: The mixture is treated under visible light irradiation to inhibit the bacterial species; ③ Evaluation of antibacterial effect: The number of colonies before and after treatment is determined by plate colony counting method, and the antibacterial rate is calculated.

[0021] The beneficial effects of this invention are: This invention prepares boron azonitride (BNAD) by undergoing a diazotization-coupling reaction with h-BN; further, nano-sized Cu is loaded onto the BNAD. x O (x=1 or 2) constructs a heterojunction to obtain Cu x O / BNAD composite photocatalyst. This structure achieves efficient electron-hole separation through effective interfacial coupling, improving the response to visible light and electron transfer efficiency, thus significantly enhancing photocatalytic activity. Under simulated sunlight, Cu... x O / BNAD can effectively reduce Cr(VI) ions, with an apparent kinetic constant of 0.071 min. -1 The conversion rate is as high as 88.67%. Under visible light irradiation, it can effectively inhibit the reproduction of Gram bacteria, with an antibacterial rate of 98.0-99.9%. The preparation method of this invention is simple, low-cost, highly efficient, recyclable, and does not cause secondary environmental pollution. It is suitable for the field of photocatalytic wastewater treatment, especially in Cr(VI) reduction and bacterial elimination, showing great application potential. Attached Figure Description

[0022] Figure 1 The examples include p-BNNS, p-BNAD, and Cu at different calcination temperatures and with different Cu contents. x FTIR spectrum of O / BNAD; Figure 2 p-BNAD solid-state nuclear magnetic resonance spectrum 11 B spectrum and 13 C-spectrum, * represents rotating sidebands; Figure 3 p-BNNS, p-BNAD, and Cu in Example 1 x O 8.3 / BNAD 100 UV-vis DRS spectrum; Figure 4 The N2 adsorption-desorption curve of p-BNAD; Figure 5 Cu samples prepared for p-BNNS, p-BNAD, and different calcination temperatures x O 8.3 XRD pattern of / BNAD; Figure 6 p-BNNS, p-BNAD and Cu x O 8.3 / BNAD 100 SEM photos; Figure 7 p-BNAD and Cu with different metal contents x O / BNAD 100 First-order kinetic curve of photocatalytic reduction of Cr(VI) by the complex; Figure 8 The Cu sample prepared under the conditions of Cu elemental percentage of p-BNNS at 8.3 wt.% and calcination temperature at 100 ℃ has Cu content... x O 8.3 / BNAD 100 right E. coli and S. aursue The relationship between antibacterial properties and time; Figure 9 Unexposed to light without photocatalyst E. coli and sample Cu x O 8.3 / BNAD 100 After 45 min and 90 min of illumination E. coli SEM photos; Figure 10 Unexposed to light without photocatalyst S. aureus and sample Cu x O 8.3 / BNAD 100 After 45 min and 90 min of illumination S. aureus SEM photos; Figure 11 p-BNAD and CuxO prepared in Example 1 8.3 / BNAD 100 The complex produces EPR spectra of the active ingredient under both darkness and light conditions; Figure 12 p-BNAD and Cu with different metal contents x O / BNAD 100 A comparison of the conversion rates of the composite material in the photocatalytic reduction of Cr(VI) under different light sources. Detailed Implementation

[0023] This invention first utilizes a soft template method to prepare porous h-BN (p-BNNS) by high-temperature calcination of the precursor. Taking advantage of the high-density primary amine content on the surface and edges of p-BNNS, it is reacted with nitrous acid to generate p-BNNS-based diazonium salts (Formulas 1 and 2). Furthermore, by controlling the weakly acidic reaction conditions, the h-BN diazonium salts are induced to undergo a coupling reaction with the coupling agent N,N-dimethylaniline, ultimately efficiently synthesizing porous boron nitride azo compound (p-BNAD) (Formula 3) covalently linked by -N=N-azo bonds.

[0024] The diazotization reaction and coupling reaction are shown in equations (1) to (3).

[0025]

[0026] This invention further employs a vacuum impregnation method with copper salts to prepare copper oxide / boron azonitride (Cu). x O / BNAD) composite photocatalyst, wherein the pH value is adjusted to 9.0 using ammonia water, Cu 2+ Partially reduced to Cu + A mixture of CuO and Cu2O was obtained. x The resulting composite photocatalyst exhibits significantly enhanced photocatalytic activity and antibacterial properties.

[0027] (I) Reasons for the Enhanced Photocatalytic Activity The key to improving photocatalytic performance lies in the structural modification of the boron nitride matrix by the azotization reaction, and its interaction with copper oxide nanoparticles (Cu). x The synergistic effect of O NPs. The specific principle is as follows: (1) Structural optimization and increase of active sites The original p-BNNS has a compact layered structure, high chemical inertness, and few active sites. If Cu... x O is directly loaded onto p-BNNS, Cu x O-agglomeration leads to a decrease in effective active surface area. This invention introduces aromatic groups (such as N,N-dimethylaniline) covalently linked by "-N=N-" azo bonds onto p-BNNS via a diazotization-coupling reaction, forming p-BNAD. This process utilizes the fused aromatic ring structure in the azo component to enhance van der Waals forces (F∝r) through steric hindrance and surface π-electron repulsion. -6 The exponential decay promotes interlayer peeling, disrupts its regular lattice, and introduces a large number of defects and abundant functional groups.

[0028] Anchor point multiplication: These defects and functional groups act as uniform and robust anchor points, enabling Cu... xO NPs can be highly dispersed and stably loaded in the pores of the p-BNAD matrix, avoiding aggregation. This significantly increases the number of effective catalytic active sites in the composite material.

[0029] (2) The light absorption capacity is significantly broadened Unazo-treated p-BNNS absorbs light primarily in the ultraviolet region. The azo-treated p-BNAD exhibits π-π conjugation of the azo bond and aromatic ring, similar to that of p-BNNS. sp 2 The hybrid system forms a complete p-orbital overlap, expands the electron delocalization range, and at the same time constructs a quantum well structure in the band gap, introduces intermediate energy levels, creates new electronic transition channels, significantly reduces the photoexcitation energy barrier, and realizes a wide-spectral response of p-BNAD.

[0030] According to UV-vis DRS analysis, the light absorption range of the p-BNAD matrix itself has extended to the near-infrared region (800~1400 nm). Figure 3 This allows the composite to capture photons more effectively across the full spectrum, improving photocatalytic efficiency. When Cu exhibits a strong localized surface plasmon resonance (LSPR) effect... x When O NPs are loaded onto p-BNAD, the two work synergistically to further improve photocatalytic performance.

[0031] (3) Improved efficiency of photogenerated carrier separation and transport Under 300 W (λ>420 nm) xenon lamp irradiation, Cu x The O / BNAD complex generates abundant photogenerated electron-hole pairs. Photogenerated electrons transition from the valence band (VB) to the conduction band (CB), and the azotized structure of p-BNAD and Cu... x The O NPs interface forms a tight heterojunction, which facilitates the transfer of electrons from Cu. x The rapid transfer of O to p-BNAD significantly enhances carrier separation and migration rates. Simultaneously, it suppresses the recombination rate of electron-hole pairs, effectively maintaining redox capabilities. This further improves reactive oxygen species (ROS), such as ·OH and ·O2. - The quantum yield of ¹O2) promotes the activity of photocatalytic reduction of Cr(VI).

[0032] (II) Specific reasons for the improved antibacterial properties Cu x The antibacterial properties of the O / BNAD complex are mainly achieved through photoinduced ROS generation and a physicochemical synergistic mechanism. EPR (electron paramagnetic resonance) testing confirmed that the antibacterial active components include ·OH and ·O2. - and ¹O2 (see Figure 11 (Figures a, b, and c in the diagram). The specific mechanism is as follows: ·OH、·O2 - ¹O2 disrupts the function and structure of bacterial cell membranes through lipid peroxidation, leading to loss of membrane permeability and leakage of cell contents. As a highly reactive reactive oxygen species (ROS), ¹O2 can penetrate the cell membrane and directly damage the intracellular matrix, including genetic material such as mitochondria, DNA, and the Golgi apparatus, inhibiting gene replication and cell metabolism. x O NPs enter cells via osmosis, causing protein denaturation and ultimately bacterial death. Simultaneously, the rough edges of the complex surface (originating from the opening of p-BNAD structures) create mechanical damage, forming a physical barrier. These chemical (ROS-induced oxidation) and physical (mechanical damage) mechanisms work synergistically to significantly enhance antibacterial efficiency.

[0033] This invention Cu x In the O / BNAD composite catalyst, the Cu loading ranges from 4.2 wt.% to 10.0 wt.%. When the loading is too low, there are insufficient active sites, resulting in limited improvement in photocatalytic efficiency; when the loading is too high (e.g., 12.0 wt.%), excessive Cu... x O NPs exhibit severe aggregation, which not only reduces the effective active surface area but also covers some active sites on the p-BNAD surface, hindering their own photogenerated carrier generation and separation. Furthermore, excessively dense Cu... x O NPs may block the incident light, reducing the overall light absorption efficiency.

[0034] In this invention, the calcination temperature is controlled at 100~200℃ during the copper salt loading process onto p-BNAD. The Cu prepared at this calcination temperature... x The O / BNAD composite photocatalyst exhibits high efficiency and long-lasting photocatalytic performance. This is because: (1) To form ideal copper oxide particle size and dispersion uniformity, and to introduce an appropriate amount of defects, the active surface area and catalytic active sites are maximized. The calcination temperature of 100~200℃ is relatively mild, which helps copper species to form nanoparticles of moderate size, good dispersion and certain crystallinity on the p-BNAD surface. Suitable crystallinity is conducive to the transport of charge carriers inside the crystal, while uniformly dispersed small-sized particles provide a larger active surface area and more reaction sites.

[0035] (2) It avoids damage to the structural integrity and stability of the p-BNAD substrate. When the calcination temperature exceeds 200℃, the key chromophore responsible for light absorption in the p-BNAD substrate material—the azo group (-N=N-)—will undergo irreversible thermal decomposition or breakage. This will directly destroy the molecular structure and π-π conjugated system of p-BNAD, thereby significantly changing its electronic energy level structure, causing a sharp decline in the inherent light absorption capacity of p-BNAD, and severely damaging its structural stability as a support and synergistic photocatalyst. When the calcination temperature is below 100℃ or no calcination is performed, the supported copper salt will mainly remain in the form of copper salt, rather than being transformed into copper oxide. Even if partial dehydration occurs, the copper atoms fail to form a stable oxide lattice. Due to the failure to form a stable copper oxide crystalline phase, the interfacial interaction between the copper salt and the p-BNAD substrate is weak, and an effective CuxO / BNAD heterojunction cannot be formed. Under light irradiation, the photogenerated electron-hole pairs will be difficult to separate effectively, resulting in poor catalytic performance. In addition, copper salt precursors typically have high water solubility or chemical instability, and are prone to dissolution, loss, or further non-selective reactions in actual photocatalytic reaction environments, resulting in unstable catalyst performance and short lifespan.

[0036] Therefore, strictly controlling the calcination temperature within 100~200℃ is a crucial process strategy in this invention. This approach balances the optimization of copper oxide crystal size and defects while effectively avoiding thermal damage to the p-BNAD substrate, ensuring the high efficiency and longevity of the composite material's photocatalytic performance.

[0037] Cu x The specific process by which O / BNAD composite photocatalysts reduce Cr(VI) pollutant in water and inhibit the growth of Gram bacteria: (1) Photocatalytic reduction of Cr(VI) test A Cr(VI) solution with a concentration of 25 mg / L was used as the target pollutant. 12 mg of Cu was added to 40 mL of the Cr(VI) solution. x The O / BNAD composite catalyst was used, and the initial pH of the system was adjusted to the range of 2-4 using 1 mol / L HCl and NaOH solutions. The system was then stirred and allowed to adsorb in the dark for 1 h under no-light conditions to ensure the catalyst reached adsorption-desorption equilibrium. Subsequently, xenon lamp irradiation was applied, and the system was continuously stirred at 300 r / min, with absorbance measured every 5-20 min. The filtrate was filtered through a filter and poured into a quartz cuvette. UV-Vis spectrophotometry was used to scan the filtrate in the wavelength range of 200-600 nm, and the absorbance change at 352 nm was observed and recorded. The conversion rate of Cr(VI), C / C0, was calculated using the formula:

[0038] in, C Represents the concentration of Cr(VI). C 0 represents the initial concentration. C t The concentration at reaction time t.

[0039] (2) Photocatalytic antibacterial test Gram-negative bacteria Escherichia coli ( E. coli ) and Gram-positive bacteria Staphylococcus aureus ( S. aureus Using the model bacteria, the antibacterial ability of the photocatalyst was evaluated by plate count method.

[0040] First, sterilize the petri dishes, culture medium, pipette tips, and other related equipment and reagents in an autoclave for later use. E. coli and S. aureus At 180 rmp·min -1 A bacterial suspension in the logarithmic growth phase was obtained by thoroughly shaking and culturing in a 37 ℃ constant temperature shaking incubator for 18 h, and its OD was measured. 600 Values. The concentrations of the bacterial suspensions were calculated based on the standard curves of the two bacterial strains, and then diluted to 1.0 × 10⁻⁶. 5 ~1.0×10 6 CFU·mL -1 Subsequently, 1 mL of diluted bacterial suspension and 2 mg of photocatalyst were mixed thoroughly. The untreated bacterial suspension served as a blank control. Both were incubated under a xenon lamp with a filter (λ>420 nm) at the same temperature and rotation speed to allow the catalyst to fully exert its antibacterial effect. After a period of illumination, 100 μL of the bacterial suspension was evenly spread onto a 100 mm diameter agar plate and incubated at 37°C for 18 h. Bacterial growth was observed, colony counts were recorded, and the sterilization rate was calculated by comparing with the blank control. The bacterial inhibition rate was calculated using the following formula: Antibacterial rate (%) = ( N b - N t ) / N b × 100% in, N t It refers to the number of bacterial colonies in the experimental group, while N b This represents the number of colonies in the control group.

[0041] The present invention will be further described below with reference to the embodiments. Example 1

[0042] Melamine, urea, and boric acid were mixed in a molar ratio of 1:0.5:2. 0.631 g of melamine, 0.15 g of urea, and 0.619 g of boric acid were weighed out, along with approximately ten times the weight of the chemicals in grinding beads. These mixtures were placed in two grinding jars, sealed, and then placed in a ball mill. The mixture was ball-milled at 600 r / min for 15 min to obtain the h-BN precursor. Next, 3.5 g of the precursor and 1.5 g of pore-forming agent (ammonium bicarbonate) were placed in a mortar and ground evenly. The mixture was then calcined in a tube furnace at 850 ℃ for 4 h and cooled to room temperature to obtain p-BNNS.

[0043] Accurately measure 2 mL of concentrated hydrochloric acid and dilute it to 10 mL with deionized water; weigh 0.2 g of p-BNNS and add it to the solution, then place it in an ice-water bath at 0-5 ℃; dissolve 0.123 g of NaNO2 in 5 mL of deionized water, and slowly add it dropwise to the above solution while stirring continuously for 15 min. The resulting solution is labeled as solution A; measure 0.2 mL of N,N-dimethylaniline and mix it evenly with 0.154 mL of acetic acid, then slowly add it dropwise to solution A while stirring continuously for 10 min; then add 3.84 mL of 5% NaOH aqueous solution to the mixture, mix well, and place it in a water bath at 60 ℃ for 6-7 min. After naturally cooling to room temperature, place it in an ice-water bath for thorough cooling, filter, and wash with anhydrous ethanol to obtain p-BNAD.

[0044] Infrared and solid-state NMR characterization revealed that azo groups were successfully grafted onto p-BNNS. Figure 1 and Figure 2 ).exist Figure 1 In the infrared spectrum, azo-functionalized p-BNAD and Cu x The O / BNAD complex was at 1650 cm⁻¹. -1 A weak absorption peak appears at this point, corresponding to the stretching vibration peak of the -N=N- bond. Figure 2 The a-figure in the image represents p-BNAD. 11 BMAS NMR spectrum. A signal peak was observed at 20.8 ppm. 3-coordinated boron 11 The chemical shift range of B is 90 to -10 ppm, which is due to the sp. 2 Hybridization indicates that the intrinsic structure of h-BN has not been disrupted. Figure 2 The b-figure in the image represents p-BNAD. 13 The C2M NMR spectrum showed a C signal peak at 161.7 ppm, which was attributed to the benzene ring, indicating that the aromatic ring on N,N-dimethylaniline was successfully grafted onto p-BNNS to prepare the p-BNAD matrix material.

[0045] Furthermore, azotization significantly expanded the absorption range of p-BNAD light, even extending it to the near-infrared region. Figure 3 Its specific surface area is 2.87 m². 2 / g, with an average pore size of 13.4 nm ( Figure 4 ).

[0046] Weigh 0.200 g of p-BNAD and 0.015 g of PVP into a 25 mL beaker. Add CuCl2 (Cu elemental mass percentage of p-BNAD is 8.3 wt.%) to the beaker, along with 15 mL of deionized water. Impregnate the copper salt into the p-BNAD channels under vacuum for 2 h, followed by sonication for 20 min. Then, under magnetic stirring, add an appropriate amount of ammonia to adjust the pH of the solution to approximately 9.0. Continue sonication for 20 min, place in an 80 ℃ water bath, and add 40% NaOH aqueous solution dropwise until precipitation is complete. Dry the precipitate in a 60 ℃ vacuum oven for 10 h, and finally calcine at 100 ℃ for 1 h to obtain Cu. x O 8.3 / BNAD 100 Composite photocatalyst (8.3 represents the percentage of Cu element mass in p-BNAD mass, 100 represents the calcination temperature). XRD characterization revealed that copper oxide was successfully loaded onto p-BNAD. Figure 5 After loading copper oxide, a whisker-like structure grows at the edge of the photocatalyst, exposing more active sites. Figure 6 ).

[0047] Cu prepared under the above conditions x O 8.3 / BNAD 100 Photocatalytic reduction of Cr(VI) was conducted using a photocatalyst. A 25 mg / L Cr(VI) solution was used as the target pollutant. 12 mg of photocatalyst was added to 40 mL of the Cr(VI) solution, and the initial pH of the system was adjusted to 3 using 1 mol / L HCl and NaOH solutions. The stirring device was started, and the system was allowed to adsorb in the dark for 1 h under no-light conditions to reach adsorption-desorption equilibrium. Subsequently, a xenon lamp was turned on, and the system was continuously stirred at 300 r / min. The absorbance of the system was measured every 5 min. The filtrate was filtered through a filter and placed in a quartz cuvette. The changes in the absorption peak of Cr(VI) during the catalytic reduction reaction were characterized using ultraviolet-visible absorption spectroscopy (UV-vis). The experimental results showed that Cu... x O 8.3 / BNAD 100 The apparent rate constant for the photocatalytic reduction of Cr(VI) reaches 0.071 min.-1 ( Figure 7 The conversion rate was 88.67%. Simultaneously, a high-power infrared LED was used as the light source, irradiating the prepared Cu with a wavelength of 810 nm. x O 8.3 / BNAD 100 The photocatalyst was used to perform a photocatalytic reduction reaction of Cr(VI), and the measured conversion rate was still as high as 86.88% (see...). Figure 12 ).

[0048] Under the same photocatalytic conditions, the photocatalytic Cr(VI) reduction performance of p-BNAD was tested. Under full-light xenon lamp illumination, the conversion rate of Cr(VI) was 69.24%, and under 810 nm infrared light irradiation, the conversion rate was 60.84%. Comparison shows that the Cu prepared in this application... x O 8.3 / BNAD 100 The photocatalyst exhibits significantly improved photocatalytic reduction performance compared to p-BNAD.

[0049] Photocatalytic antibacterial test: Using Gram-negative Escherichia coli and Gram-positive Staphylococcus aureus as model bacteria, the antibacterial ability of the photocatalyst was evaluated using the plate count method. Bacteria were cultured to the logarithmic growth phase, and the photocatalyst was applied at a concentration of 1.0 × 10⁻⁶. 5 CFU·mL -1 20 mg of photocatalyst was added to 1 mL of bacterial culture, followed by irradiation under a 300 W xenon lamp with a 420 nm filter for 30 min. No photocatalyst was added to the control group. Every 10 min, 100 μL of bacterial culture was taken and spread evenly on the surface of a solid culture medium, and then incubated at 37℃ for 18 h to observe bacterial growth, take pictures and record the data, and calculate the inhibition rate.

[0050] After 30 minutes of illumination, Cu x O 8.3 / BNAD 100 Photocatalysts E. coli and S. aureus The antibacterial rates were 72% and 56%, respectively.

[0051] Cu x O 8.3 / BNAD 100 After 50 minutes of light exposure, E. coli and S. aureus Both bacteria can achieve a 100% sterilization rate. Figure 8 Untreated with photocatalysts E. coli It exhibits a full, rod-like structure, approximately 3–5 μm in length and 0.5–1 μm in diameter (e.g., Figure 9(See Figures a and b in the image). After the photocatalyst reacts under visible light for 45 minutes, observations can be made. E. coli The particles adhere and accumulate on the catalyst surface, and the cell morphology shows depressions and breaks. Figure 9 (Figure c) After 90 minutes, it can be clearly observed that the cell wall edges are blurred, cells adhere to each other, and cells die. Figure 9 (Figure d in the diagram).

[0052] In addition, untreated catalyst S. aureus It exhibits a full, spherical structure (see...) Figure 10 (See Figures a and b in the image). After the photocatalyst reacts under visible light for 45 minutes, observations can be made. S. aureus Bacteria attach and accumulate on the catalyst surface ( Figure 10 (Figure c) After 90 minutes, the cell wall edges became blurred, cells adhered to each other, and cells died. Figure 10 (Figure d in the diagram). Example 2

[0053] The preparation methods for p-BNNS and p-BNAD are the same as in Example 1.

[0054] Weigh 0.200 g of p-BNAD and 0.015 g of PVP into a 25 mL beaker. Add CuCl2 (Cu element mass percentage of p-BNAD is 4.2 wt.%) to the beaker and add 15 mL of deionized water. Impregnate the copper salt into the channels of p-BNNS under vacuum for 2 h, followed by sonication for 20 min. Then, under magnetic stirring, add an appropriate amount of ammonia to adjust the pH of the solution to around 9.0. Continue sonication for 20 min, place in an 80 ℃ water bath, and add 40% NaOH aqueous solution until precipitation is complete. Then, dry the precipitate in a 60 ℃ vacuum oven for 10 h, and finally calcine at 100 ℃ for 1 h to obtain Cu. x O 4.2 / BNAD 100 Composite photocatalyst (4.2 represents the percentage of Cu element mass in p-BNAD mass, 100 represents the calcination temperature).

[0055] Cu prepared under the above conditions x O 4.2 / BNAD 100 The photocatalyst was used to test the photocatalytic reduction reaction of Cr(VI), and the experimental procedure was as described in Example 1. Under full light, Cu... x O 4.2 / BNAD 100 The apparent rate constant for the photocatalytic reduction of Cr(VI) is 0.066 min.-1 (See Figure 7 The conversion rate was 85.50% under 810nm irradiation and 83.25% under 810nm irradiation (see...). Figure 12 ). Example 3

[0056] The preparation methods for p-BNNS and p-BNAD are the same as in Example 1.

[0057] Weigh 0.200 g of p-BNAD and 0.015 g of PVP into a 25 mL beaker. Add CuCl2 (Cu content of p-BNNS is 8.3%) to the beaker and add 15 mL of deionized water. Impregnate the copper salt into the pores of the p-BNNS under vacuum for 2 h, followed by sonication for 20 min. Then, under magnetic stirring, add an appropriate amount of ammonia to adjust the pH of the solution to around 9.0. Continue sonication for 20 min, place in an 80 ℃ water bath, and add 40% NaOH aqueous solution until precipitation is complete. Then, dry the precipitate in a 60 ℃ vacuum oven for 10 h, and finally calcine at 200 ℃ for 1 h to obtain the copper oxide / boron azonitride composite nanocatalyst Cu. x O 8.3 / BNAD 200 (8.3 represents the percentage of Cu mass in the p-BNNS mass, and 200 represents the calcination temperature).

[0058] Cu prepared under the above conditions x O 8.3 / BNAD 200 The photocatalyst was used to test the photocatalytic reduction reaction of Cr(VI), and the experimental procedure was as described in Example 1. Cu x O 8.3 / BNAD 200 The apparent rate constant for the photocatalytic reduction of Cr(VI) is 0.068 min. -1 . Example 4

[0059] The preparation method of p-BNNS is the same as that in Example 1.

[0060] Accurately measure 2 mL of concentrated hydrochloric acid and dilute it to 10 mL with deionized water; weigh 0.2 g of p-BNNS and add it to the solution, then place it in an ice-water bath at 0-5 ℃; dissolve 0.123 g of NaNO2 in 5 mL of deionized water, slowly add it dropwise to the above solution, and stir continuously for 15 min, labeling the resulting solution as solution A; measure 0.154 mL of aniline and 0.154 mL of acetic acid and mix them evenly, then slowly add them dropwise to solution A, and stir continuously for 10 min; then add 3.84 mL of 5% NaOH aqueous solution to the mixture, mix well, and place it in a water bath at 60 ℃ for 6-7 min, cool it naturally to room temperature, then place it in an ice-water bath to cool it completely, filter it, and wash it with anhydrous ethanol to obtain p-BNAD.

[0061] Cu x The preparation method of the O / BNAD complex is the same as that of Cu in Example 1. x O 8.3 / BNAD 100 The preparation was consistent, and Cu was obtained. x O 8.3 / BNAD′ 100 .

[0062] Cu prepared under the above conditions x O 8.3 / BNAD′ 100 The composite was subjected to a photocatalytic antibacterial test, using the same method as in Example 1. After 30 min of illumination, Cu... x O 8.3 / BNAD 100 Photocatalysts E. coli and S. aureus The antibacterial rates were 61% and 47%, respectively. Comparative Example 1

[0063] The preparation methods for p-BNNS and p-BNAD are the same as in Example 1.

[0064] Weigh 0.200 g of p-BNAD and 0.015 g of PVP into a 25 mL beaker. Add CuCl2 (Cu element mass percentage of p-BNAD is 12.0 wt.%) to the beaker and add 15 mL of deionized water. Impregnate the copper salt into the pores of p-BNAD under vacuum for 2 h, then sonicate for 20 min. Next, under magnetic stirring, add an appropriate amount of ammonia to adjust the pH of the solution to around 9.0; continue sonicating for 20 min, then place in an 80 ℃ water bath and add 40% NaOH aqueous solution until precipitation is complete. Then dry the precipitate in a 60 ℃ vacuum oven for 10 h, and finally calcine at 100 ℃ for 1 h to obtain Cu.x O 12.0 / BNAD 100 Composite photocatalyst (12.0 represents the percentage of Cu element mass in p-BNAD mass, 100 represents the calcination temperature).

[0065] Cu prepared under the above conditions x O 12.0 / BNAD 100 The photocatalyst was used to test the photocatalytic reduction reaction of Cr(VI), and the experimental procedure was as described in Example 1. Cu x O 12.0 / BNAD 100 The apparent rate constant for the photocatalytic reduction of Cr(VI) is 0.023 min. -1 (See Figure 7 The conversion rate was 53.80%, and under 810nm infrared light irradiation, the conversion rate was 47.52% (see...). Figure 12 The reason for the deterioration of photocatalytic reduction performance may be due to Cu. x O loading is too high, and there is excessive Cu. x O NPs can aggregate severely, which not only reduces the effective active surface area but also covers some active sites on the p-BNAD surface, hindering the generation and separation of photogenerated carriers and thus reducing photocatalytic performance. Comparative Example 2

[0066] The preparation methods for p-BNNS and p-BNAD are the same as in Example 1.

[0067] Weigh 0.200 g of p-BNAD and 0.015 g of PVP into a 25 mL beaker. Weigh CuCl2 (Cu element mass percentage of p-BNNS is 8.3 wt.%) into the beaker and add 15 mL of deionized water. Impregnate the copper salt into the pores of the p-BNNS under vacuum for 2 h, then sonicate for 20 min. Next, under magnetic stirring, add an appropriate amount of ammonia to adjust the pH of the solution to approximately 9.0; continue sonicating for 20 min, then place in an 80 ℃ water bath and add 40% NaOH aqueous solution until precipitation is complete. Then dry the precipitate in a 60 ℃ vacuum oven for 10 h to obtain Cu. x O 8.3 / BNAD RT Composite nanophotocatalyst (8.3 represents the percentage of Cu element mass in p-BNAD mass, RT represents room temperature conditions).

[0068] Cu prepared under the above conditions x O 8.3 / BNAD RTThe photocatalyst was used to test the photocatalytic reduction reaction of Cr(VI), and the experimental procedure was as described in Example 1. Cu x O 8.3 / BNAD RT The apparent rate constant for the photocatalytic reduction of Cr(VI) is 0.042 min. -1 .

Claims

1. A Cu x The method for preparing O / BNAD composite photocatalysts is characterized by: The preparation method includes the following steps: Step a, preparation of p-BNNS: Melamine, urea and boric acid are mixed and ball-milled to obtain h-BN precursor. The h-BN precursor and pore-forming agent are ground evenly and then calcined at high temperature in a tube furnace to obtain porous boron nitride nanosheets (p-BNNS). Step b, preparation of p-BNAD: ① Diazotization reaction: After diluting concentrated hydrochloric acid, add p-BNNS and place in an ice-water bath at 0~5 ℃; dissolve NaNO2 in deionized water and slowly add it dropwise to the above solution and stir to obtain solution A; ② Coupling reaction: The coupling agent is mixed with acetic acid and slowly added dropwise to solution A. Then, 5% NaOH aqueous solution is added to the mixture. After mixing evenly, the mixture is placed in a water bath at 60 °C for 6-7 min and kept warm for a long time. After cooling completely, the mixture is filtered and washed to finally obtain boron azonitride (p-BNAD). Step c, Cu x Preparation of O / BNAD: Weigh p-BNAD, a protective agent, and a certain mass of CuCl2 into a beaker, add deionized water, and impregnate under vacuum for 2 h. Adjust the pH to 9.0 by adding ammonia dropwise. Place this system in an 80 ℃ water bath and add a 40% NaOH aqueous solution dropwise until precipitation is complete. Then, dry the precipitate to constant weight and calcine at a certain temperature for 1 h to obtain CuCl2. x O / BNAD composite photocatalyst.

2. The Cu according to claim 1 x The method for preparing O / BNAD composite photocatalysts is characterized by: In step a, the molar ratio of melamine, urea, and boric acid is 1:0.3~0.6:1~3; the porogen is one of ammonium bicarbonate, magnesium sulfate, or barium sulfate; and the mass ratio of the h-BN precursor to the porogen is 5:5~8:

2.

3. The Cu according to claim 1 x The method for preparing O / BNAD composite photocatalysts is characterized by: In step a, the calcination temperature is 850 ℃, the calcination time is 4 h, and the calcination heating rate is 5 ℃ / min.

4. The Cu according to claim 1 x The method for preparing O / BNAD composite photocatalysts is characterized by: In step b, the concentration of the concentrated hydrochloric acid after dilution is 20% (2 mL of concentrated hydrochloric acid diluted to 10 mL), and the volume-to-mass ratio of dilute hydrochloric acid to p-BNNS is 10 mL: 0.2 g; the concentration of the NaNO2 aqueous solution is 22~25 mg / mL.

5. The Cu according to claim 1 x The method for preparing O / BNAD composite photocatalysts is characterized by: In step b, the coupling agent is one of N,N-dimethylaniline or other aromatic amine organic compounds, the volume ratio of the coupling agent to acetic acid is 1.54~2:1.54, the volume-to-mass ratio of the coupling agent to p-BNNS is 0.1~0.2mL:0.2~0.4g, and the volume ratio of 5% NaOH aqueous solution to solution A is 3~4:

15.

6. The Cu according to claim 1 x The method for preparing O / BNAD composite photocatalysts is characterized by: In step c, the protective agent is polyvinylpyrrolidone (PVP), the mass ratio of p-BNAD to the protective agent is 4:0.2~0.4, and the mass percentage of Cu element in CuCl2 relative to the mass of p-BNAD is 4.2 wt.%~10.0 wt.%.

7. The Cu according to claim 1 x The method for preparing O / BNAD composite photocatalysts is characterized by: In step c, the calcination temperature is 100~200 ℃.

8. A Cu x O / BNAD composite photocatalyst, characterized in that: Cu prepared by the preparation method according to any one of claims 1-7 x O / BNAD composite photocatalyst, wherein Cu x O is a mixture of CuO and Cu2O.

9. A Cu as described in claim 8 x The application of O / BNAD composite photocatalysts is characterized by: The Cu x O / BNAD composite photocatalysts are used to reduce Cr(VI) pollutant in water and inhibit the growth of Gram bacteria.

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