Graphdiyne-loaded bimetallic nano material for VOCs adsorption and preparation method of graphdiyne-loaded bimetallic nano material

Abstract

The invention provides a preparation method of a graphdiyne-loaded bimetallic nano material for VOCs adsorption. The preparation method comprises the following steps: S1, synthesizing a large-area and low-defect graphdiyne film by using an in-situ interface growth method; and S2, loading bimetallic nanoparticles on the surface of graphdiyne by adopting a co-impregnation-step reduction method. Meanwhile, the invention provides the graphdiyne-loaded bimetallic nano-material for VOCs adsorption, the graphdiyne-loaded bimetallic nano-material is prepared by adopting the preparation method, the graphdiyne-loaded bimetallic nano-material comprises Cu-Ag alloy nano-particles and Cu + active sites, Cu + accounts for 90% or above of the total copper content, and the nano-particles are anchored to the graphdiyne ring through a Cu-O-C equivalent key; in the aspects of stability and regeneration performance, after 20 times of adsorption-desorption cycle tests, the material capacity retention rate is gt; 90%.

Description

Technical Field

[0001] The present invention belongs to the technical field of environmental functional materials and volatile organic compound (VOCs) pollution control, and particularly relates to a graphdiyne-supported bimetallic nanomaterial for VOCs adsorption and a preparation method thereof. Background Art

[0002] Volatile organic compounds (VOCs), especially toxic gases such as formaldehyde, are the main pollutants in indoor air. The efficient removal technology thereof has always been a research hotspot in the field of environmental governance. At present, the adsorption method is widely used due to advantages such as simple operation and controllable cost. Although traditional adsorption materials such as activated carbon and zeolite have been industrially applied, problems such as low adsorption capacity (for example, the adsorption capacity of activated carbon for formaldehyde is only 15-20 mg / g), poor selectivity, and rapid attenuation of regeneration performance (the capacity is often lower than 50% after multiple cycles) need to be solved urgently.

[0003] In recent years, two-dimensional carbon materials (such as graphene and graphdiyne) have become ideal carriers for loading metal nanoparticles to construct efficient adsorption materials due to their high specific surface area, rich surface functional groups, and unique electronic structure. Among them, graphdiyne, as a new type of all-carbon two-dimensional conjugated material, contains a large number of alkyne bond active sites. Theoretically, it can enhance the chemical adsorption of VOCs through coordination, but there are the following key bottlenecks in the existing technology:

[0004] Insufficient control of carrier defects: The defect density of graphdiyne thin films grown on traditional solid substrates (such as silicon wafers and copper foils) is high (>1μm -2 ), resulting in difficulty in breaking through the specific surface area (usually <1000m 2 / g), and the defect sites are prone to cause aggregation of metal nanoparticles, reducing the utilization rate of active sites.

[0005] Difficulty in regulating the uniformity and valence state of metal loading: Existing co-reduction or single reducing agent methods are difficult to precisely control the dispersion of bimetals (such as Cu-Ag) and the valence state of Cu (it is easy to generate inert Cu 0 or residual Cu 2+ ), while Cu + has a unique synergistic effect on formaldehyde adsorption in the alkyne bond coordination environment, and insufficient proportion thereof will significantly affect the adsorption performance.

[0006] Poor cycle stability: During the adsorption-desorption process of traditional materials, metal particles are prone to loss or aggregation, resulting in rapid attenuation of capacity (for example, the capacity decays to 50-70% after 20 cycles), and it is difficult to meet the long-term use requirements.

[0007] As an emerging carbon allotrope, graphdiyne is composed of benzene rings and alkyne bonds (-C≡C-), and naturally forms uniformly distributed nano-scale pores (about 0.5 - 2.5 nm). The pore size matches the kinetic diameters of most VOCs molecules (such as benzene, formaldehyde, etc.), enabling size-selective adsorption. In contrast, the pores of graphene need to be generated through chemical modification or physical activation.

[0008] Therefore, there is an urgent need to develop a preparation method for VOCs adsorption materials with high specific surface area and high cycle stability.

[0009] In view of this, the present application is specifically proposed. Summary of the Invention

[0010] To solve one of the above technical deficiencies, the embodiments of the present application provide a graphdiyne-supported bimetallic nanomaterial for VOCs adsorption and its preparation method.

[0011] The technical solution of the present application provides a preparation method for a graphdiyne-supported bimetallic nanomaterial for VOCs adsorption, including the following steps:

[0012] S1, Synthesize a large-area, low-defect graphdiyne film using the in-situ interface growth method;

[0013] S2, Load bimetallic nanoparticles on the surface of graphdiyne using the co-impregnation-stepwise reduction method.

[0014] Preferably, step S1 specifically includes the following steps:

[0015] (1) Use liquid metal as the growth substrate to form a Ga2O3 catalytic layer;

[0016] (2) Use a polyalkynyl aromatic compound solution as the precursor solution, and construct a two-dimensional graphdiyne network through dehydrogenation coupling reaction in an inert / weak reducing atmosphere;

[0017] (3) After electrochemical exfoliation and annealing treatment, perform vacuum filtration, and obtain the graphdiyne film after vacuum drying.

[0018] Preferably, step S2 specifically includes the following steps:

[0019] (1) Dissolve copper nitrate trihydrate and silver nitrate in an ethanol-water mixed solvent, and add polyvinylpyrrolidone to obtain a bimetallic salt solution;

[0020] (2) Grind the graphdiyne film to obtain graphdiyne powder, pretreat the graphdiyne powder and add it to the bimetallic salt solution, and process it under preset conditions;

[0021] (3) Ascorbic acid with a molar ratio of 2:1 to silver ions was added and reacted, after which the silver ions were reduced; the silver-loaded graphdiyne was redispersed in ethanol, and after stirring and reacting in an oil bath under a mixed gas of H2, an intermediate product of a copper-silver double-loaded graphdiyne coating layer was obtained;

[0022] (4) The copper-silver double-loaded graphdiyne coating layer formed after stepwise reduction was washed and dried to obtain a graphdiyne-supported bimetallic nanomaterial.

[0023] Preferably, a liquid metal was used as the growth substrate to form a Ga2O3 catalytic layer; the specific method was as follows: the liquid metal was pickled to remove the oxide layer, rinsed with deionized water, and the surface residual liquid was briefly blown, and then exposed to an oxygen-containing environment for 5 to 30 minutes to form an oxide layer with a thickness of 1 to 5 nm on its surface, and irradiated with near-ultraviolet light with a wavelength > 365 nm for 10 to 30 minutes.

[0024] Preferably, the precursor solution was prepared as follows: hexaynylbenzene was dissolved in a tetrahydrofuran solution, a dispersant was added, and ultrasonic treatment was carried out for 30 minutes to fully dissolve; the liquid metal substrate was fixed on a spin coater and the precursor solution was spin-coated at a speed of 2000 rpm for 60 seconds; it was transferred to a closed reaction kettle, and a mixed gas of Ar / H2 was introduced, and the reaction was carried out at 40 to 60 °C for 10 to 15 hours.

[0025] Preferably, a polycarbonate filter membrane with a pore size of 0.22 μm was used for vacuum filtration;

[0026] The vacuum drying conditions were vacuum drying at 60 °C for 12 hours;

[0027] Electrochemical exfoliation was to immerse the grown sample in a 0.1 M NaCl electrolyte solution and apply a DC voltage of 0.8 to 1 V for 10 to 15 minutes;

[0028] Annealing treatment was to place the exfoliated graphdiyne film in a tube furnace and heat it to 250 °C at a rate of 5 °C / min under an Ar atmosphere.

[0029] Preferably, the Cu:Ag molar ratio in copper nitrate trihydrate and silver nitrate was 1:1 to 3:1;

[0030] The volume ratio of the ethanol-water mixed solvent was 4:1;

[0031] The treatment under the preset conditions was specifically to disperse for 30 minutes under an ultrasonic power of 100 W, then stir in a water bath at 40 °C for 12 hours, adjust the pH of the system to 5.5 with an ammonia water solution with a concentration of 0.1 ± 0.01 M, and maintain for 30 minutes.

[0032] The embodiment of the present application also provides a graphdiyne-supported bimetallic nanomaterial for VOCs adsorption, which is prepared by the above preparation method. In the graphdiyne-supported bimetallic nanomaterial, Cu-Ag alloy nanoparticles and Cu + active sites, where Cu + accounts for more than 90% of the total copper content. The nanoparticles are anchored on the graphdiyne alkyne ring through Cu-O-C≡ bonds.

[0033] Preferably, in the graphdiyne-supported bimetallic nanomaterial,

[0034] the particle size distribution of the bimetallic particles is 2.5-4.0 nm;

[0035] Preferably, the graphdiyne-supported bimetallic nanomaterial for VOCs adsorption undergoes 20 adsorption-desorption cycle tests, and the material capacity retention rate > 90%.

[0036] Advantages of the present application:

[0037] 1. The present application innovatively uses the in-situ interface growth method to synthesize a large-area, low-defect graphdiyne film, and then uses the co-impregnation-step reduction method to load bimetallic nanoparticles on the surface of graphdiyne to synthesize a VOCs adsorption material. First, an ultrathin Ga2O3 catalytic layer (3 nm) in-situ generated by a gallium-indium eutectic alloy is used. Through its high surface activity and uniform interface characteristics, it guides the directional dehydrogenation coupling of hexaynylbenzene molecules to form a two-dimensional graphdiyne network with low defects (I_D / I_G = 0.15), solving the technical bottleneck of the disordered growth of carbon materials in the traditional chemical vapor deposition method. Second, an innovative step reduction process is adopted. After selectively reducing silver ions with ascorbic acid, the reduction degree of copper species is precisely controlled in an Ar / H2 mixed atmosphere, so that Cu exists as Cu + (verified by XPS to account for more than 95%) and Ag 0 coexist to form atomically dispersed bimetallic active sites. The nanoparticles are anchored on the graphdiyne alkyne ring through Cu-O-C≡ bonds, and the strong coordination adsorption of Cu + and the electronic synergistic effect of Ag 0 significantly improve the VOCs adsorption efficiency. Furthermore, by combining electrochemical exfoliation and low-temperature annealing technology (250 °C), while maintaining the high crystallinity of graphdiyne, a strong anchoring effect is exerted on metal nanoparticles by its surface electron-rich channels (the capacity retention rate > 90% after 20 cycles), breaking through the technical problem of easy agglomeration and deactivation of metal particles in traditional supporting materials. This method realizes three technical breakthroughs in carrier structure optimization, precise regulation of active sites, and stability enhancement through process collaborative innovation.

[0038] 2. The graphdiyne-supported bimetallic nanomaterial prepared in the present application has a high specific surface area. The specific surface area of the graphdiyne carrier is 1200-1500 m2 / g, in combination with the synergistic effect of bimetallic (Cu-Ag) nanoparticles, achieves a formaldehyde adsorption capacity of 40-50 mg / g at 25 °C, which is more than 150% higher than that of traditional activated carbon (15-20 mg / g). In terms of the preparation process, the present application adopts the in-situ growth technology on a liquid metal substrate, reducing the defect density of the graphdiyne film to <0.2 μm -2 , which is 90% less than that of the solid substrate (>1 μm -2 ); the stepwise reduction process enables the dispersion uniformity of the bimetallic nanoparticles to reach more than 95% and the particle size distribution of the bimetallic particles to be 4.5-6.0 nm; the mild reduction with H2 effectively inhibits the complete reduction of Cu (Cu 0 ) or the residual oxidized state (Cu 2+ ). In terms of stability and regeneration performance, after 20 adsorption-desorption cycle tests, the material capacity retention rate >90% (the traditional material decays to 50-70%). Description of the Drawings

[0039] The drawings described herein are used to provide a further understanding of the present application and constitute a part of the present application. The schematic embodiments of the present application and their descriptions are used to explain the present application and do not constitute an improper limitation of the present application. In the drawings:

[0040] Figure 1 is the Raman spectrum of the composite material prepared in Example 1 of the present invention;

[0041] Figure 2 is the SEM image of the composite material prepared in Example 1 of the present invention;

[0042] Figure 3 is the XPS peak fitting diagram of the composite material prepared in Example 1 of the present invention;

[0043] Figure 4 is the cyclic test curve of the composite material prepared in Example 1 of the present invention. Detailed Description of the Invention

[0044] In order to make the technical solutions and advantages in the embodiments of the present application clearer, the following further details the exemplary embodiments of the present application with reference to the drawings. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than an exhaustive list of all embodiments. It should be noted that, without conflict, the embodiments in the present application and the features in the embodiments can be combined with each other.

[0045] The embodiments of the present application provide a preparation method of a graphdiyne-supported bimetallic nanomaterial for VOCs adsorption, including the following steps:

[0046] Step 1: Use liquid metal as the growth substrate to form a Ga2O3 catalytic layer with a thickness of about 3 nm; specifically, the liquid metal is a gallium-indium eutectic alloy.

[0047] The specific steps are as follows: Immerse the gallium-indium eutectic alloy (Ga:In = 75.5:24.5 wt%) in a 10% HCl solution for pickling for 5 minutes to remove the oxide layer, rinse it 3 times with deionized water, and blow the surface residual liquid with nitrogen. Expose it to an ozone environment with a concentration of 50 ppm for 15 minutes to form a 3-nm-thick Ga2O3 catalytic layer on the substrate surface.

[0048] Step 2: Select a polyalkynyl aromatic compound such as hexaethynylbenzene as the precursor, and construct a two-dimensional graphdiyne network through a dehydrogenative coupling reaction in an inert / weakly reducing atmosphere; specifically, in this application, the polyalkynyl aromatic compound used is hexaethynylbenzene;

[0049] The specific steps are as follows: Dissolve hexaethynylbenzene in tetrahydrofuran to prepare a 0.1 M solution, add 0.5 wt% polyvinylpyrrolidone (PVP, Mw = 55,000) as a dispersant, and ultrasonically treat it for 30 minutes (power 100 W, frequency 40 kHz). Fix the liquid metal substrate on a spin coater and spin coat the precursor solution at 2000 rpm for 60 seconds to form a uniformly thick liquid film. Transfer the substrate to a high-pressure reactor, introduce an Ar / H2 mixed gas (volume ratio 95:5, flow rate 50 sccm), and maintain the pressure at 0.2 MPa. React at 50 °C for 12 hours, and the liquid metal surface catalyzes the dehydrogenative coupling of hexaethynylbenzene molecules to form a continuous two-dimensional graphdiyne network (Raman spectroscopy detection characteristic peak: intensity of D peak / intensity of G peak = 0.15, indicating a low defect density).

[0050] Step 3: Through electrochemical exfoliation and annealing treatment, use a polycarbonate filter membrane with a pore size of 0.22 μm for vacuum filtration, and vacuum dry at 60 °C for 12 hours to obtain a self-supporting graphdiyne film and obtain high-purity graphdiyne powder;

[0051] The specific steps are as follows: Immerse the grown sample in a 0.1 M NaCl electrolyte solution, apply a DC voltage of 1.0 V for 12 minutes for electrochemical exfoliation (the current density is stable at 0.5 mA / cm 2 ). The exfoliated graphdiyne film is collected by vacuum filtration with a polycarbonate filter membrane (pore size 0.22 μm), placed in a tube furnace, heated to 250 °C at a rate of 5 °C / min, and annealed in an Ar atmosphere for 2 hours.

[0052] Step 4: Dissolve copper nitrate trihydrate and silver nitrate in an ethanol-water mixed solvent with a volume ratio of 4:1 according to the Cu / Ag molar ratio = 2:1, and control the total metal ion concentration to be 0.1 M; add 0.1% of polyvinylpyrrolidone based on the total mass of the solution to obtain a metal salt solution;

[0053] Step 5: Add 100 mg of pretreated graphdiyne powder to the above metal salt solution, disperse it for 30 minutes under the condition of an ultrasonic power of 100 W; then stir it in a water bath at 40 °C for 12 hours, adjust the pH of the system to 5.5 with 0.1 M ammonia water solution, and maintain it for 30 minutes;

[0054] Step 6: Add ascorbic acid with a molar ratio of 2:1 to silver ions, react for 60 minutes at 25 °C under dark conditions, and the silver ions are reduced. Redisperse the silver-loaded graphdiyne in ethanol, introduce an Ar / H2 mixed gas with a volume ratio of 95:5, and stir at a stirring rate of 300 rpm in an oil bath at 80 °C for 105 minutes;

[0055] Step 7: Wash and dry the Cu-Ag dual-loaded graphdiyne coating formed by stepwise reduction to obtain a graphdiyne-supported bimetallic nanomaterial.

[0056] Specific steps: Centrifugally wash alternately with ethanol and deionized water (rotation speed 8000 rpm, 5 minutes each time) until the pH is neutral. Dry in vacuum at 60 °C for 12 hours to obtain the final material.

[0057] Figure 1 This is the Raman spectrum of the composite material prepared in Example 1 of the present invention. The intensity ratio I_D / I_G of the D peak (1350 cm -1 ) and the G peak (1580 cm -1 ) of the graphdiyne film is 0.15, indicating that the liquid metal substrate (such as Ga-In alloy) effectively inhibits the structure during the growth of graphdiyne, making the prepared graphdiyne film have high structural order and low defect density.

[0058] Figure 2 This is the SEM image of the composite material prepared in Example 1 of the present invention, which reflects the microscopic morphology of the prepared material.

[0059] It can be seen from the figure that a large number of nanoparticles are uniformly loaded on the surface of the graphdiyne carrier. The particle size distribution range is 4.5 - 6.0 nm (statistical sample number n = 200), and the average particle size is 5.1 ± 1.3 nm (Gaussian fitting, R 2 = 0.98). The nanoparticles are quasi-spherical, without obvious agglomeration phenomenon, and the dispersion uniformity reaches 96%. The bimetallic nanoparticles are atomically dispersed on the surface of graphdiyne, and the Cu-Ag element distribution is uniform, providing a structural basis for the synergistic adsorption effect.

[0060] Figure 3 This is the XPS peak fitting diagram of the composite material prepared in Example 1 of the present invention. It is confirmed that the binding energy positioning of the Cu 2p orbital peak fitting shows that Cu +(Cu2O): The binding energy of the main peak of Cu 2p1 / 2 is 952.3 eV, the 2p3 / 2 peak is located at 932.5 eV, and the spacing of 19.8 eV conforms to the valence state characteristics of Cu + ; No obvious Cu 2+ signal related to Cu 0 was detected.

[0061] It is proved that through the stepwise reduction process of mild reduction with H2, the complete reduction of Cu (Cu 0 ) or the residual oxidation state (Cu 2+ ) is effectively inhibited, and the Cu element mainly exists in the sample in the form of Cu + . The analysis of the Ag 3d orbital also confirms that the binding energy of the Ag 3d5 / 2 peak is 368.1 eV (corresponding to metallic silver), the 3d3 / 2 peak is 374.1 eV, the double-peak spacing is 6.0 eV, and the full width at half maximum is 1.2 eV. There is no significant oxidation state signal (such as the 3d5 / 2 peak of Ag2O should be located at 367.5 eV), indicating that silver exists in the elemental state. The XPS data clearly confirm the coexistence state of Cu + and Ag 0 in the material, which is consistent with the designed stepwise reduction process (first reducing Ag + and then partially reducing Cu 2+ ), providing a valence basis for the bimetallic synergistic adsorption mechanism.

[0062] Figure 4 Furthermore, it shows that after 20 adsorption-desorption cycles, the formaldehyde adsorption capacity retention rate of the composite material is still higher than 90%. This excellent cycle stability is attributed to the high crystallinity of the graphdiyne carrier and the strong anchoring effect of the bimetallic nanoparticles. By precisely regulating the Cu + active sites and low-temperature desorption conditions through the stepwise reduction process, the particle migration and agglomeration and the inactivation of active sites are synergistically inhibited, maintaining the structural integrity of the material.

[0063] Example 2:

[0064] The difference from Example 1 is that in Step 4: Cu / Ag molar ratio = 1.1. In Step 6, the reduction order is adjusted: first reduce Cu and then reduce Ag.

[0065] Example 3:

[0066] The difference from Example 1 is that in Step 4: Cu / Ag molar ratio = 3.1.

[0067] Example 4:

[0068] The difference from Example 1 is that in Step 1: a gallium-tin alloy (Ga:Sn = 92:8 wt%) is used to replace the gallium-indium eutectic alloy as the liquid metal substrate.

[0069] Comparative Example 1: Graphdiyne material loaded with only Cu monometal

[0070] The preparation of the graphdiyne substrate and the preparation of the metal salt solution in Steps 1 to 5 are the same as those in Example 1.

[0071] Step 6: Introduce an Ar / H2 mixed gas with a volume ratio of 95:5, and stir at a stirring rate of 300 rpm in an oil bath at 80 °C for 105 minutes;

[0072] Step 7: Wash and dry the copper-loaded graphdiyne coating layer formed after stepwise reduction to obtain a graphdiyne-supported monometal nanomaterial.

[0073] Specific steps: Centrifuge and wash alternately with ethanol and deionized water (rotation speed 8000 rpm, 5 minutes each time) until the pH is neutral. Dry in vacuum at 60 °C for 12 hours to obtain the final material.

[0074] Comparative Example 2: Graphdiyne material loaded with only Ag monometal

[0075] A preparation method of a graphdiyne-supported bimetal nanomaterial for VOCs adsorption, comprising the following steps:

[0076] The preparation of the graphdiyne substrate and the preparation of the metal salt solution in Steps 1 to 5 are the same as those in Example 1.

[0077] Step 6: Add ascorbic acid with a molar ratio of 2:1 to silver ions, and react at 25 °C under light-shielded conditions for 60 minutes, and the silver ions are reduced.

[0078] Step 7: Wash and dry the silver-loaded graphdiyne coating layer formed after stepwise reduction to obtain a graphdiyne-supported monometal nanomaterial.

[0079] Specific steps: Centrifuge and wash alternately with ethanol and deionized water (rotation speed 8000 rpm, 5 minutes each time) until the pH is neutral. Dry in vacuum at 60 °C for 12 hours to obtain the final material.

[0080] Comparative Example 3: Performance differences of samples with different Cu + / Cu 0 ratio

[0081] A preparation method of a graphdiyne-supported bimetal nanomaterial for VOCs adsorption, comprising the following steps:

[0082] The preparation of the graphdiyne substrate and the preparation of the metal salt solution in Steps 1 to 5 are the same as those in Example 1.

[0083] Step 6: Add ascorbic acid with a molar ratio of 2:1 to silver ions, react for 60 minutes at 25°C under light protection conditions, and the silver ions are reduced. Redisperse the silver-loaded graphdiyne in ethanol, introduce an Ar / H2 mixed gas with a volume ratio of 95:5, and stir in an oil bath at 80°C at a stirring rate of 300 rpm for 90 minutes;

[0084] Step 7: Wash and dry the copper-silver double-loaded graphdiyne coating layer formed by stepwise reduction to obtain a graphdiyne-supported bimetallic nanomaterial.

[0085] Specific steps: Alternately centrifuge and wash with ethanol and deionized water (rotation speed 8000 rpm, 5 minutes each time) until the pH is neutral. Vacuum dry at 60°C for 12 hours to obtain the final material.

[0086] Comparative Example 4: Performance differences of different Cu + / Cu 0 ratio samples

[0087] A preparation method of a graphdiyne-supported bimetallic nanomaterial for VOCs adsorption, comprising the following steps:

[0088] The preparation of the graphdiyne substrate and the preparation of the metal salt solution in Steps 1 to 5 are the same as those in Example 1.

[0089] Step 6: Add ascorbic acid with a molar ratio of 2:1 to silver ions, react for 60 minutes at 25°C under light protection conditions, and the silver ions are reduced. Redisperse the silver-loaded graphdiyne in ethanol, introduce an Ar / H2 mixed gas with a volume ratio of 95:5, and stir in an oil bath at 80°C at a stirring rate of 300 rpm for 120 minutes;

[0090] Step 7: Wash and dry the copper-silver double-loaded graphdiyne coating layer formed by stepwise reduction to obtain a graphdiyne-supported bimetallic nanomaterial.

[0091] Specific steps: Alternately centrifuge and wash with ethanol and deionized water (rotation speed 8000 rpm, 5 minutes each time) until the pH is neutral. Vacuum dry at 60°C for 12 hours to obtain the final material.

[0092] Test the composite materials prepared in the above Example 1 and Comparative Examples 1-2, and the test results are shown in Table 1.

[0093] Real-time monitoring: Use a customized glass adsorption column (inner diameter 10 mm, filled with 50 mg of material), and connect it to a constant-temperature circulating water bath (25 °C). The inlet end is equipped with a formaldehyde standard gas generator (50 ppm, balanced with N2), and the flow rate is controlled at 100 mL / min (calibration error of the mass flowmeter ±1%). Online gas chromatography (GC-FID, Agilent 7890B) is used to detect the outlet gas concentration. Samples are taken once every 5 minutes for the first 30 minutes; after 30 minutes: samples are taken once every 10 minutes; continue until the outlet concentration reaches 95% of the inlet concentration (determined as adsorption saturation).

[0094] Data processing: Calculate the adsorption capacity through the adsorption kinetics model - pseudo-second-order kinetic model (formula: )

[0095] Table 1

[0096]

[0097]

[0098] Table 1 shows the comparison of the performance parameters of the graphdiyne-supported metal nanomaterials prepared in different examples and comparative examples, including the pseudo-second-order rate constant, equilibrium adsorption capacity, time required to reach 80% Qe, metal loading, and specific surface area. From the data, it can be seen that the pseudo-second-order rate constant, equilibrium adsorption capacity, and specific surface area of the examples are all better than those of the comparative examples. This reflects that the preparation method described in the present invention effectively improves the pore structure and adsorption capacity of the material through the metal double-loading process.

[0099] The composite materials prepared in the above Example 1 and Comparative Examples 3 - 4 were tested, and the test results are shown in Table 2.

[0100] Use an X-ray photoelectron spectrometer (XPS, Thermo Scientific K-Alpha, Al Kα ray (1486.6 eV), pass energy 50 eV, step size 0.1 eV) to decompose the Cu 2p3 / 2 peak into: Cu + (binding energy 932.5 ± 0.2 eV, satellite peak intensity ratio < 0.3), Cu 0 (binding energy 933.8 ± 0.2 eV, no significant satellite peak). Determine the Cu + / Cu 0 ratio according to the peak area ratio, and repeat the test 3 times and take the average value.

[0101] Table 2

[0102]

[0103] Table 2 shows the comparison of the performance parameters of the graphdiyne-supported bimetallic nanomaterials prepared in Example 1 and the comparative example. The main research is on the influence of the Cu valence ratio (Cu + / Cu 0 ) on the VOCs adsorption performance. By precisely controlling the reduction conditions, samples with different Cu + proportions were prepared, and adsorption performance tests and characterization analyses were carried out. This reflects that the preparation method described in the present invention effectively improves the adsorption rate of the material and significantly shortens the adsorption equilibrium time through the copper-silver double loading process.

[0104] In summary, the present invention combines the in-situ interface growth method with the co-impregnation-stepwise reduction method to achieve the precise preparation of the graphdiyne-supported bimetallic nanomaterials; by constructing a graphdiyne carrier with a high specific surface area and synergistically acting with the bimetallic nanoparticles, while effectively improving the adsorption capacity for VOCs such as formaldehyde, the material stability and regeneration performance are significantly enhanced; at the same time, the application of the in-situ growth technology of the liquid metal substrate and the stepwise reduction process not only reduces the material defect density but also improves the dispersion uniformity of the nanoparticles. Compared with the existing VOCs adsorption materials, the materials of the present invention have achieved a comprehensive innovation in terms of adsorption performance and preparation process, etc., opening up a new path for the research and development of high-efficiency VOCs adsorption materials.

[0105] Although the preferred embodiments of the present application have been described, those skilled in the art can make additional changes and modifications once they know the basic creative concept. Therefore, the appended claims are intended to be interpreted as including the preferred embodiments and all changes and modifications falling within the scope of the present application.

[0106] Obviously, those skilled in the art can make various changes and modifications to the present application without departing from the spirit and scope of the present application. Thus, if these modifications and variations of the present application fall within the scope of the claims of the present application and their equivalent technologies, the present application also intends to include these modifications and variations.

Claims

1. A preparation method of a graphdiyne-supported bimetallic nanomaterial for VOCs adsorption, characterized in that, It includes the following steps: S1. Synthesize a large-area and low-defect graphdiyne film by in-situ interface growth method; S2. Load bimetallic nanoparticles on the surface of graphdiyne by co-impregnation-stepwise reduction method.

2. The preparation method of the graphdiyne-supported bimetallic nanomaterial for VOCs adsorption according to claim 1, characterized in that, Step S1 specifically includes the following steps: (1) Use liquid metal as the growth substrate to form a Ga2O3 catalytic layer; (2) Use a polyalkynyl aromatic compound solution as the precursor solution, and construct a two-dimensional graphdiyne network through dehydrogenative coupling reaction in an inert / weakly reducing atmosphere; (3) After electrochemical exfoliation and annealing treatment, perform vacuum filtration, and obtain the graphdiyne film after vacuum drying.

3. The preparation method of the graphdiyne-supported bimetallic nanomaterial for VOCs adsorption according to claim 1, characterized in that, Step S2 specifically includes the following steps: (1) Dissolve copper nitrate trihydrate and silver nitrate in an ethanol-water mixed solvent, and add polyvinylpyrrolidone to obtain a bimetallic salt solution; (2) Grind the graphdiyne film to obtain graphdiyne powder, pretreat the graphdiyne powder and then add it to the bimetallic salt solution, and treat it under preset conditions; (3) Add ascorbic acid with a molar ratio of 2:1 to silver ions, and after reaction, the silver ions are reduced; redisperse the silver-loaded graphdiyne in ethanol, and stir and react in an oil bath under a H2 mixed gas to obtain an intermediate product of a copper-silver double-loaded graphdiyne coating; (4) Wash and dry the copper-silver double-loaded graphdiyne coating formed after stepwise reduction to obtain a graphdiyne-supported bimetallic nanomaterial.

4. The preparation method of the graphdiyne-supported bimetallic nanomaterial for VOCs adsorption according to claim 2, characterized in that, Use liquid metal as the growth substrate to form a Ga2O3 catalytic layer; the specific method is: pickling the liquid metal to remove the oxide layer, rinsing with deionized water, briefly blowing the surface residual liquid, and then exposing it to an oxygen-containing environment for 5-30 minutes to form an oxide layer with a thickness of 1-5 nm on its surface, and irradiating it with near-ultraviolet light with a wavelength > 365 nm for 10-30 minutes.

5. The preparation method of the graphdiyne-supported bimetallic nanomaterial for VOCs adsorption according to claim 2, wherein, The preparation method of the precursor solution is: dissolve hexaynylbenzene in a tetrahydrofuran solution, add a dispersant, and ultrasonically treat for 30 minutes to fully dissolve; fix the liquid metal substrate on a spin coater, and spin coat the precursor solution at a speed of 2000 rpm for 60 seconds; transfer it to a closed reaction kettle, introduce an Ar / H2 mixed gas, and react at 40-60 °C for 10-15 hours.

6. The preparation method of the graphdiyne-supported bimetallic nanomaterial for VOCs adsorption according to claim 2, wherein The vacuum filtration uses a polycarbonate filter membrane with a pore size of 0.22 μm; The vacuum drying condition is vacuum drying at 60 °C for 12 hours; The electrochemical exfoliation is to immerse the grown sample in a 0.1 M NaCl electrolyte solution and apply a DC voltage of 0.8-1 V for 10-15 minutes; The annealing treatment is to place the exfoliated graphdiyne film in a tube furnace and heat it to 250 °C at a rate of 5 °C / min under an Ar atmosphere.

7. The preparation method of the graphdiyne-supported bimetallic nanomaterial for VOCs adsorption according to claim 3, wherein The molar ratio of Cu:Ag in copper nitrate trihydrate and silver nitrate is 1:1-3:1; The volume ratio of the ethanol-water mixed solvent is 4:1; The treatment under preset conditions is specifically to disperse for 30 minutes under the condition of an ultrasonic power of 100 W, then stir in a water bath at 40 °C for 12 hours, adjust the pH of the system to 5.5 with an ammonia water solution with a concentration of 0.1 ± 0.01 M, and maintain for 30 minutes.

8. A graphdiyne-supported bimetallic nanomaterial for VOCs adsorption, characterized in that, Prepared by the preparation method according to any one of claims 1-7, in the graphdiyne-supported bimetallic nanomaterial, Cu-Ag alloy nanoparticles and Cu + active sites, wherein Cu + accounts for more than 90% of the total copper content, and the nanoparticles are anchored on the graphdiyne alkyne ring through Cu-O-C≡ bonds.

9. The graphdiyne-supported bimetallic nanomaterial for VOCs adsorption according to claim 8, wherein, In the described graphdiyne-supported bimetallic nanomaterial, The particle size distribution of the bimetallic particles is 2.5 - 4.0 nm.

10. The graphdiyne-supported bimetallic nanomaterial for VOCs adsorption according to claim 8, wherein, The graphdiyne-supported bimetallic nanomaterial for VOCs adsorption undergoes 20 adsorption-desorption cycle tests, and the material capacity retention rate > 90%.

Images