Non-noble metal HEAs / CN photocatalytic material for degrading micro-plastic and synergistically producing hydrogen and preparation method of non-noble metal HEAs / CN photocatalytic material

Abstract

The invention belongs to the field of environmental pollution abatement, and particularly relates to a non-noble metal HEAs / CN photocatalytic material for degrading micro-plastics to synergistically produce hydrogen and a preparation method of the non-noble metal HEAs / CN photocatalytic material. The preparation method specifically comprises the following steps: mixing CN two-dimensional nanosheets and HEAs, drying by distillation, and calcining to obtain the HEAs / CN photocatalyst, and the mass of the HEAs in the HEAs / CN material is 1-30% of the mass of CN. The photocatalyst disclosed by the invention has the advantages of strong light response capability, high photon-generated carrier separation efficiency and the like. Experiments prove that the HEAs / CN photocatalyst is good in synergistic hydrogen production when used for photocatalytic degradation of PET / PLA micro-plastics by visible light, and the hydrogen production rate within 4 hours can reach 422.96 [mu] mol / g.h and 558.72 [mu] mol / g.h as high as 422.96 [mu] mol / g.h and 558.72 [mu] mol / g.h.

Description

Technical Field

[0001] The present invention belongs to the field of environmental waste resource utilization, and particularly relates to a non-precious metal HEAs / CN photocatalytic material for degrading microplastics and synergistically producing hydrogen and a preparation method thereof. Background Art

[0002] The ecological hazards of plastics include the risk of marine ecosystem collapse and the degradation of terrestrial ecosystems. In the ocean, plastic fragments have been found in 94% of seabirds and 100% of sea turtles worldwide, leading to gastric perforation, malnutrition, and death after ingestion. Abandoned fishing nets kill over 300,000 marine mammals (whales, seals, and others) annually, causing a 15-20% decline in populations. Chemical toxicity and accumulation within the food chain also pose serious risks to human health. On land, the average concentration of microplastics in farmland soils globally reaches 2,000 pieces per kilogram. Soil porosity in areas containing agricultural film has decreased by 40%, resulting in a 12% reduction in crop yields. Furthermore, exposure to microplastics reduces the reproduction rate of earthworms and reduces the efficiency of soil organic matter decomposition.

[0003] To date, plastic disposal methods include incineration, landfilling, mechanical recycling, and chemical conversion. Incineration and landfilling are the least desirable because they cause the most pollution and have little economic benefit. Mechanical recycling is a mature technology, with 80% of recycled plastics worldwide relying on physical recycling and a high penetration rate of equipment. However, mechanical recycling cannot handle mixed plastics (such as multilayer packaging films) or highly contaminated waste (recycling rates <5%). In addition, most recycled plastics processed through melting and re-extrusion have a smaller molecular weight, thermal mass, and mechanical quality than virgin plastics, resulting in inferior performance. Chemical conversion can handle mixed plastics, contaminated waste, and can produce high-value products, but chemical conversion often requires higher temperatures, pressures, and energy consumption, and its carbon emission intensity is three times that of physical recycling. Unlike chemical conversion, photocatalytic recycling of polymers does not involve high heat and pressure, and has therefore received widespread attention in recent years. Photocatalytic degradation of microplastics is an emerging environmentally friendly technology. Its core is to use photocatalysts to produce active substances under light conditions, breaking down microplastics into small molecules or completely mineralizing them. During the photocatalytic process, photocatalysts generate a large number of electrons (e - ) and holes (h + High-energy photogenerated carriers can trigger various redox reactions under mild conditions. Photocatalytic degradation of microplastics is not only environmentally friendly and pollution-free, but also features a regenerative catalyst and mild reaction conditions. Combining the three core advantages of high efficiency, environmental friendliness, and low energy consumption, photocatalytic degradation of microplastics is an ideal solution to address microplastic pollution.

[0004] Currently, there are two major challenges in the preparation and application of non-precious metal photocatalytic materials for the synergistic hydrogen production from microplastic degradation. First, there is a lack of research on the relationship between HEAs / CN and photoconversion performance when the composite contains more than three metal elements. Second, HEAs nanoparticles are relatively small, with numerous surface defects, making them extremely unstable and prone to bonding with other atoms. Furthermore, their magnetic properties make them more prone to aggregation. Summary of the Invention

[0005] The purpose of the present invention is to provide a non-precious metal HEAs / CN photocatalytic material for the synergistic production of hydrogen by degrading microplastics. The preparation process of this material is simple and low-cost. The non-precious metal material avoids releasing toxic metal ions when degrading microplastics. Applying this catalyst to the degradation of microplastics and the synergistic production of hydrogen can effectively inhibit the agglomeration of HEAs nanoparticles and improve the photocatalytic efficiency.

[0006] The technical solution adopted by the present invention to solve its technical problem is:

[0007] A method for preparing a non-noble metal HEAs / CN photocatalytic material for degrading microplastics and synergistically producing hydrogen, the method comprising the following steps:

[0008] S1, weighing an appropriate amount of urea into a ceramic crucible with a lid, calcining in air, and cooling to room temperature after calcination to obtain graphite carbon nitride (g-C3N4, CN);

[0009] S2, weighing appropriate amounts of iron (III) acetylacetonate, cobalt (III) acetylacetonate, nickel (II) acetylacetonate, copper (II) acetylacetonate, and manganese (II) acetylacetonate into a polytetrafluoroethylene-lined hydrothermal reactor, performing a solvothermal reaction at a temperature of 180±20°C for 18-30 hours. After the reaction, the mixture was cooled to room temperature and centrifuged and dried to obtain high entropy alloy nanoparticles (HEANPs) (HEAs);

[0010] S3, mixing the CN obtained in step S1, the HEAs obtained in step S2, and anhydrous ethanol, sonicating, stirring, and evaporating in a water bath to dryness to obtain a HEAs / CN mixture; the weight ratio of HEAs to CN is 1 to 30:100;

[0011] S4, placing the HEAs / CN mixture obtained in step S3 in a ceramic crucible with a cover and calcining it under the protection of an inert gas, and naturally cooling it to room temperature after the calcination to obtain a HEAs / CN photocatalyst.

[0012] Transmission electron microscopy (TEM) confirmed that HEAs were uniformly dispersed on the CN nanosheets.

[0013] The material preparation process is simple: large-scale production can be achieved through a solvent thermal method without the need for complex equipment; the raw material cost is low: the price of non-precious metals (such as Fe, Co, Ni, Cu, etc.) is only 1% to 10% of that of precious metals (Pt, Au, Pd); there is no risk of secondary pollution: non-precious metal materials avoid releasing toxic metal ions when degrading microplastics, which conforms to the principles of green chemistry. The method synthesizes CN two-dimensional nanosheets through thermal polymerization, mixes CN two-dimensional nanosheets with MnFeCoNiCu nanoparticles (HEAs), and calcines them to construct a HEAs / CN photocatalyst, which is then applied to the degradation of microplastics for the synergistic production of hydrogen.

[0014] Preferably, in S1, the calcination temperature is 550±50°C, the calcination time is 3-6h, and the heating rate is 4-7°C / min.

[0015] Preferably, in S2, the concentrations of iron (III) acetylacetonate, cobalt (III) acetylacetonate, nickel (II) acetylacetonate, copper (II) acetylacetonate, and manganese (II) acetylacetonate in the reaction system are 3×10 -3 -7×10 -3 mol / L, preferably 5×10 - 3 mol / L.

[0016] Preferably, in S3, the ratio of HEAs to ethanol is 0.5-3 mg / mL, the weight ratio of HEAs to CN is 8-10:100, the ultrasonication time is 10-50 min, the water bath temperature is 50-80°C, and the water bath time is 6-9 h. The optimal mass ratio of HEAs to CN is 9:100.

[0017] Preferably, in S4, the calcination temperature is 400±50°C, the calcination time is 1-3h, and the heating rate is 3-7°C / min.

[0018] A non-precious metal HEAs / CN photocatalytic material for degrading microplastics and synergistically producing hydrogen is prepared by the method according to any one of claims 1 to 5. The high entropy alloy nanoparticles are uniformly dispersed on the surface of graphite-phase carbon nitride nanosheets.

[0019] Preferably, the HEAs in the material are MnFeCoNiCu five-element high entropy alloy nanoparticles, and the weight ratio of HEAs to CN is 8:100 to 10:100.

[0020] An application of the non-noble metal HEAs / CN photocatalytic material described in the present invention in the coordinated production of hydrogen by photocatalytic degradation of microplastics.

[0021] Preferably, the application includes the following steps: pre-treating microplastics in a 0-10 mol / L KOH solution at 40±5°C for 48±8 hours; and mixing the pre-treated microplastic aqueous solution with the non-precious metal HEAs / CN photocatalytic material in a solvent system under light conditions to achieve synergistic hydrogen production from microplastic degradation. The light conditions can be natural light, preferably a xenon lamp, and more preferably a 300W±100W xenon lamp.

[0022] Preferably, the illumination condition is visible light irradiation, the concentration of HEAs / CN photocatalyst is 0.3-0.5 mg / mL, and the concentration of microplastics is 15-20 mg / mL.

[0023] Functions and effects of the invention

[0024] In this study, a HEAs / CN photocatalyst was prepared by combining two-dimensional CN nanosheets, which have a large specific surface area and a unique electronic structure, with HEAs to form a composite. The inclusion of HEAs broadens the photoresponse range of the CN nanosheets and inhibits the recombination of photogenerated electron-hole pairs, effectively enhancing their photocatalytic activity.

[0025] To address the serious problem of microplastic pollution in our daily lives, this study proposes using non-precious metal high-entropy alloy nanoparticles loaded onto graphite carbon nitride to create a photocatalyst that can recycle microplastics in solution. When the mass ratio of HEAs to CN nanosheets is 9:100, the HEAs / CN photocatalyst achieves the highest rate of photocatalytic hydrogen production, reaching 422.96 μmol / g·h under visible light illumination for 4 hours. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 (a) is a flow chart of the preparation process of HEAs / CN photocatalysts in Examples 1-3 of the present invention; Figure 1 (bd) are TEM images and mapping diagrams of the HEAs / CN photocatalyst in Example 2 of the present invention, wherein (b) is a TEM image of the 9wt%-HEAs / CN photocatalyst obtained in Example 2; the lattice fringes in (c) are 0.201 nm, corresponding to the (111) crystal plane of HEAs; (d) is a distribution diagram of Mn, Fe, Co, Ni, and Cu elements in a selected area of the 9wt%-HEAs / CN photocatalyst obtained in Example 2;

[0027] Figure 2 It is the XRD diffraction pattern of the basic CN in Comparative Example 1 and the HEAs / CN photocatalyst in Examples 1-3 of the present invention;

[0028] Figure 3It is the UV-vis spectrum of the basic CN in Comparative Example 1 and the HEAs / CN photocatalysts in Examples 1-3 of the present invention;

[0029] Figure 4 It (a) and EIS (b) spectra of the basic CN in Comparative Example 1 and the 9wt%-HEAs / CN photocatalyst in Example 2 of the present invention;

[0030] Figure 5 The performance graph (a) of the photocatalytic hydrogen production of HEAs / CN photocatalysts in Comparative Examples 1-2 and Examples 1-3 of the present invention, and the performance graph (b) of the photocatalytic hydrogen production of HEAs / CN photocatalysts in Example 2 and Examples 4-6;

[0031] Figure 6 This is a cycle performance diagram of photocatalytic hydrogen production using 9wt%-HEAs / CN photocatalyst in Example 2 of the present invention. DETAILED DESCRIPTION

[0032] The technical solution of the present invention is further described in detail below through specific examples. It should be understood that the implementation of the present invention is not limited to the following examples, and any form of modification and / or change made to the present invention will fall within the scope of protection of the present invention.

[0033] In the present invention, unless otherwise specified, all parts and percentages are by weight, and the equipment and raw materials used are commercially available or commonly used in the art. The methods in the following examples are all conventional methods in the art unless otherwise specified.

[0034] Unless otherwise specified, the reagents used in the following examples can be purchased from conventional biochemical reagent stores.

[0035] The present invention uses a 300W xenon lamp with a 420nm cutoff filter as a light source, polyethylene terephthalate (PET) and polylactic acid (PLA) as microplastic models, and application tests are carried out in a Beijing Zhongjiao Jinyuan photochemical reactor. The generated hydrogen is measured by a Beijing Zhongjiao Jinyuan gas chromatograph GC-7920.

[0036] The core technology of the present invention is a non-precious metal HEAs / CN photocatalytic material for degrading microplastics and synergistically producing hydrogen and its preparation method. The process flow chart is as follows: Figure 1 shown.

[0037] Comparative Example 1

[0038] 5g of urea was placed in a covered ceramic crucible and calcined in a muffle furnace at 550°C for 4 hours at a heating rate of 5°C / min. This yielded a basic graphite-phase carbon nitride (CN) photocatalyst. The microplastic PET was pretreated in 10 mol / L KOH.

[0039] According to the test method for the synergistic hydrogen production by photocatalytic degradation of microplastics described in the application example, the CN photocatalyst prepared in this comparative example was subjected to the synergistic hydrogen production reaction by photocatalytic degradation of microplastics. The hydrogen production rate under visible light irradiation for 4 hours was only 19.64 μmol / g·h.

[0040] Comparative Example 2

[0041] A non-precious metal HEAs / CN photocatalytic material for degrading microplastics and synergistically producing hydrogen and a preparation method thereof, comprising the following steps:

[0042] Step 1: Weigh 5 g of melamine and put it into a ceramic crucible with a lid. Place the crucible in a muffle furnace and calcine at a temperature of 550° C. for 4 h at a heating rate of 5° C. / min to obtain basic graphite phase carbon nitride (CN).

[0043] Step 2: Weigh 0.0883 g of iron (III) acetylacetonate, 0.0890 g of cobalt (III) acetylacetonate, 0.0643 g of nickel (II) acetylacetonate, 0.0655 g of copper (II) acetylacetonate, and 0.0633 g of manganese (II) acetylacetonate into a polytetrafluoroethylene-lined hydrothermal reactor, and perform a solvothermal reaction at 200° C. for 24 h. After the reaction is completed, cool to room temperature, centrifuge at 12000 rpm for 3 min, and dry to obtain high entropy alloy nanoparticles (HEAs);

[0044] Step 3: 300 mg of CN obtained in step 1, 27 mg of HEAs obtained in step 2, and 20 ml of anhydrous ethanol were mixed, ultrasonically mixed for 30 minutes, and then kept in a 70°C water bath for 6 hours. The solvent was evaporated to dryness, and the resulting solid was a HEAs / CN mixture.

[0045] Step 4: Place the HEAs / CN mixture obtained in step 3 in a ceramic crucible with a lid, calcine at 400°C for 2h under inert gas protection with a heating rate of 5°C / min, and naturally cool to room temperature after calcination to obtain a 9wt%-HEAs / CN-m photocatalyst.

[0046] Step 5: The microplastic PET is pretreated in 10 mol / L KOH.

[0047] In the 9wt%-HEAs / CN-m photocatalyst obtained above, the weight ratio of HEAs to CN is 9:100.

[0048] According to the test method for the synergistic hydrogen production from photocatalytic degradation of microplastics described in the application example, the 9wt%-HEAs / CN-m photocatalyst prepared in this comparative example was used to perform the synergistic hydrogen production from photocatalytic degradation of microplastics. The hydrogen production rate under visible light irradiation for 4 hours could reach 180.22 μmol / g·h.

[0049] Example 1

[0050] A non-precious metal HEAs / CN photocatalytic material for degrading microplastics and synergistically producing hydrogen and a preparation method thereof, comprising the following steps:

[0051] Step 1: Weigh 5 g of urea and put it into a ceramic crucible with a lid. Place the crucible in a muffle furnace and calcine at a temperature of 550° C. for 4 h at a heating rate of 5° C. / min to obtain basic graphite phase carbon nitride (CN).

[0052] Step 2: Weigh 0.0883 g of iron (III) acetylacetonate, 0.0890 g of cobalt (III) acetylacetonate, 0.0643 g of nickel (II) acetylacetonate, 0.0655 g of copper (II) acetylacetonate, and 0.0633 g of manganese (II) acetylacetonate into a polytetrafluoroethylene-lined hydrothermal reactor, and perform a solvothermal reaction at 200 ° C for 24 h. After the reaction is completed, cool to room temperature, centrifuge at 12000 rpm for 3 min, and dry to obtain high entropy alloy nanoparticles HEANPs (HEAs);

[0053] Step 3: 300 mg of CN obtained in step 1, 24 mg of HEAs obtained in step 2, and 20 ml of anhydrous ethanol were mixed, ultrasonically mixed for 30 minutes, and then kept in a 70° C. water bath for 6 hours. The solvent was evaporated to dryness, and the resulting solid was a HEAs / CN mixture.

[0054] Step 4: Place the HEAs / CN mixture obtained in step 3 in a ceramic crucible with a lid, calcine at 400°C for 2h under inert gas protection with a heating rate of 5°C / min, and naturally cool to room temperature after calcination to obtain 8wt%-HEAs / CN photocatalyst.

[0055] Step 5: The microplastic PET is pretreated in 10 mol / L KOH.

[0056] In the 8 wt % -HEAs / CN photocatalyst obtained above, the weight ratio of HEAs to CN is 8:100.

[0057] According to the test method for the synergistic hydrogen production from photocatalytic degradation of microplastics described in the application example, the 8wt%-HEAs / CN photocatalyst prepared in this comparative example was used to perform the synergistic hydrogen production reaction from photocatalytic degradation of microplastics. The hydrogen production rate under visible light irradiation for 4 hours could reach 361.69 μmol / g·h.

[0058] Example 2

[0059] A non-precious metal HEAs / CN photocatalytic material for degrading microplastics and synergistically producing hydrogen and a preparation method thereof, comprising the following steps:

[0060] Step 1: Weigh 5 g of urea and put it into a ceramic crucible with a lid. Place the crucible in a muffle furnace and calcine at a temperature of 550° C. for 4 h at a heating rate of 5° C. / min to obtain basic graphite phase carbon nitride (CN).

[0061] Step 2: Weigh 0.0883 g of iron (III) acetylacetonate, 0.0890 g of cobalt (III) acetylacetonate, 0.0643 g of nickel (II) acetylacetonate, 0.0655 g of copper (II) acetylacetonate, and 0.0633 g of manganese (II) acetylacetonate into a polytetrafluoroethylene-lined hydrothermal reactor, and perform a solvothermal reaction at 200 ° C for 24 h. After the reaction is completed, cool to room temperature, centrifuge at 12000 rpm for 3 min, and dry to obtain high entropy alloy nanoparticles HEANPs (HEAs);

[0062] Step 3: 300 mg of CN obtained in step 1, 27 mg of HEAs obtained in step 2, and 20 ml of anhydrous ethanol were mixed, ultrasonically mixed for 30 minutes, and then kept in a 70°C water bath for 6 hours. The solvent was evaporated to dryness, and the resulting solid was a HEAs / CN mixture.

[0063] Step 4: Place the HEAs / CN mixture obtained in step 3 in a ceramic crucible with a lid, calcine at 400°C for 2h under inert gas protection with a heating rate of 5°C / min, and naturally cool to room temperature after calcination to obtain a 9wt%-HEAs / CN photocatalyst.

[0064] Step 5: pre-treating the microplastic PET / PLA in 10 mol / L KOH.

[0065] In the 9wt%-HEAs / CN photocatalyst obtained above, the weight ratio of HEAs to CN is 9:100.

[0066] According to the test method for the synergistic hydrogen production of photocatalytic degradation of microplastics described in the application example, the 9wt%-HEAs / CN photocatalyst prepared in this comparative example was used to carry out the synergistic hydrogen production reaction of photocatalytic degradation of microplastics. The hydrogen production rate of microplastic PET under visible light illumination for 4 hours can reach 422.96μmol / g·h, and the hydrogen production rate of microplastic PLA under visible light illumination for 4 hours can reach 558.72μmol / g·h.

[0067] Example 3

[0068] A non-precious metal HEAs / CN photocatalytic material for degrading microplastics and synergistically producing hydrogen and a preparation method thereof, comprising the following steps:

[0069] Step 1: Weigh 5 g of urea and put it into a ceramic crucible with a lid. Place the crucible in a muffle furnace and calcine at a temperature of 550° C. for 4 h at a heating rate of 5° C. / min to obtain basic graphite phase carbon nitride (CN).

[0070] Step 2: Weigh 0.0883 g of iron (III) acetylacetonate, 0.0890 g of cobalt (III) acetylacetonate, 0.0643 g of nickel (II) acetylacetonate, 0.0655 g of copper (II) acetylacetonate, and 0.0633 g of manganese (II) acetylacetonate into a polytetrafluoroethylene-lined hydrothermal reactor, and perform a solvothermal reaction at 200 ° C for 24 h. After the reaction is completed, cool to room temperature, centrifuge at 12000 rpm for 3 min, and dry to obtain high entropy alloy nanoparticles HEANPs (HEAs);

[0071] Step 3: Mix 300 mg of CN obtained in step 1, 30 mg of HEAs obtained in step 2, and 20 ml of anhydrous ethanol, ultrasonically mix for 30 minutes, and then maintain in a 70°C water bath for 6 hours. Evaporate the solvent to obtain a solid HEAs / CN mixture.

[0072] Step 4: Place the HEAs / CN mixture obtained in step 3 in a ceramic crucible with a lid, calcine at 400°C for 2h under inert gas protection with a heating rate of 5°C / min, and naturally cool to room temperature after calcination to obtain a 10wt%-HEAs / CN photocatalyst.

[0073] Step 5: The microplastic PET is pretreated in 10 mol / L KOH.

[0074] In the 10 wt %-HEAs / CN photocatalyst obtained above, the weight ratio of HEAs to CN is 10:100.

[0075] According to the test method for the synergistic hydrogen production from photocatalytic degradation of microplastics described in the application example, the 10wt%-HEAs / CN photocatalyst prepared in this comparative example was used to perform the synergistic hydrogen production from photocatalytic degradation of microplastics. The hydrogen production rate under visible light irradiation for 4 hours could reach 353.76μmol / g·h.

[0076] Example 4

[0077] A non-precious metal HEAs / CN photocatalytic material for degrading microplastics and synergistically producing hydrogen and a preparation method thereof, comprising the following steps:

[0078] Step 1: Weigh 5 g of urea and put it into a ceramic crucible with a lid. Place the crucible in a muffle furnace and calcine at a temperature of 550° C. for 4 h at a heating rate of 5° C. / min to obtain basic graphite phase carbon nitride (CN).

[0079] Step 2: Weigh 0.0883 g of iron (III) acetylacetonate, 0.0890 g of cobalt (III) acetylacetonate, 0.0643 g of nickel (II) acetylacetonate, 0.0655 g of copper (II) acetylacetonate, and 0.0633 g of manganese (II) acetylacetonate into a polytetrafluoroethylene-lined hydrothermal reactor, and perform a solvothermal reaction at 200 ° C for 24 h. After the reaction is completed, cool to room temperature, centrifuge at 12000 rpm for 3 min, and dry to obtain high entropy alloy nanoparticles HEANPs (HEAs);

[0080] Step 3: 300 mg of CN obtained in step 1, 27 mg of HEAs obtained in step 2, and 20 ml of anhydrous ethanol were mixed, ultrasonically mixed for 30 minutes, and then kept in a 70°C water bath for 6 hours. The solvent was evaporated to dryness, and the resulting solid was a HEAs / CN mixture.

[0081] Step 4: Place the HEAs / CN mixture obtained in step 3 in a ceramic crucible with a lid, calcine at 400°C for 2h under inert gas protection with a heating rate of 5°C / min, and naturally cool to room temperature after calcination to obtain a 9wt%-HEAs / CN photocatalyst.

[0082] Step 5: pre-treating the microplastic PET / PLA in deionized water.

[0083] In the 9wt%-HEAs / CN photocatalyst obtained above, the weight ratio of HEAs to CN is 9:100.

[0084] According to the test method for the synergistic hydrogen production of photocatalytic degradation of microplastics described in the application example, the 9wt%-HEAs / CN photocatalyst prepared in this comparative example was used to carry out the synergistic hydrogen production reaction of photocatalytic degradation of microplastics. The hydrogen production rate of microplastic PET under visible light illumination for 4 hours can reach 3.80μmol / g·h, and the hydrogen production rate of microplastic PLA under visible light illumination for 4 hours can reach 3.63μmol / g·h.

[0085] Example 5

[0086] A non-precious metal HEAs / CN photocatalytic material for degrading microplastics and synergistically producing hydrogen and a preparation method thereof, comprising the following steps:

[0087] Step 1: Weigh 5 g of urea and put it into a ceramic crucible with a lid. Place the crucible in a muffle furnace and calcine at a temperature of 550° C. for 4 h at a heating rate of 5° C. / min to obtain basic graphite phase carbon nitride (CN).

[0088] Step 2: Weigh 0.0883 g of iron (III) acetylacetonate, 0.0890 g of cobalt (III) acetylacetonate, 0.0643 g of nickel (II) acetylacetonate, 0.0655 g of copper (II) acetylacetonate, and 0.0633 g of manganese (II) acetylacetonate into a polytetrafluoroethylene-lined hydrothermal reactor, and perform a solvothermal reaction at 200 ° C for 24 h. After the reaction is completed, cool to room temperature, centrifuge at 12000 rpm for 3 min, and dry to obtain high entropy alloy nanoparticles HEANPs (HEAs);

[0089] Step 3: 300 mg of CN obtained in step 1, 27 mg of HEAs obtained in step 2, and 20 ml of anhydrous ethanol were mixed, ultrasonically mixed for 30 minutes, and then kept in a 70°C water bath for 6 hours. The solvent was evaporated to dryness, and the resulting solid was a HEAs / CN mixture.

[0090] Step 4: Place the HEAs / CN mixture obtained in step 3 in a ceramic crucible with a lid, calcine at 400°C for 2h under inert gas protection with a heating rate of 5°C / min, and naturally cool to room temperature after calcination to obtain a 9wt%-HEAs / CN photocatalyst.

[0091] Step 5: pre-treating the microplastic PET / PLA in 1 mol / L KOH.

[0092] In the 9wt%-HEAs / CN photocatalyst obtained above, the weight ratio of HEAs to CN is 9:100.

[0093] According to the test method for the synergistic hydrogen production of photocatalytic degradation of microplastics described in the application example, the 9wt%-HEAs / CN photocatalyst prepared in this comparative example was used to carry out the synergistic hydrogen production reaction of photocatalytic degradation of microplastics. The hydrogen production rate of microplastic PET under visible light illumination for 4 hours can reach 105.74μmol / g·h, and the hydrogen production rate of microplastic PLA under visible light illumination for 4 hours can reach 76.10μmol / g·h.

[0094] Example 6

[0095] A non-precious metal HEAs / CN photocatalytic material for degrading microplastics and synergistically producing hydrogen and a preparation method thereof, comprising the following steps:

[0096] Step 1: Weigh 5 g of urea and put it into a ceramic crucible with a lid. Place the crucible in a muffle furnace and calcine at a temperature of 550° C. for 4 h at a heating rate of 5° C. / min to obtain basic graphite phase carbon nitride (CN).

[0097] Step 2: Weigh 0.0883 g of iron (III) acetylacetonate, 0.0890 g of cobalt (III) acetylacetonate, 0.0643 g of nickel (II) acetylacetonate, 0.0655 g of copper (II) acetylacetonate, and 0.0633 g of manganese (II) acetylacetonate into a polytetrafluoroethylene-lined hydrothermal reactor, and perform a solvothermal reaction at 200 ° C for 24 h. After the reaction is completed, cool to room temperature, centrifuge at 12000 rpm for 3 min, and dry to obtain high entropy alloy nanoparticles HEANPs (HEAs);

[0098] Step 3: 300 mg of CN obtained in step 1, 27 mg of HEAs obtained in step 2, and 20 ml of anhydrous ethanol were mixed, ultrasonically mixed for 30 minutes, and then kept in a 70°C water bath for 6 hours. The solvent was evaporated to dryness, and the resulting solid was a HEAs / CN mixture.

[0099] Step 4: Place the HEAs / CN mixture obtained in step 3 in a ceramic crucible with a lid, calcine at 400°C for 2h under inert gas protection with a heating rate of 5°C / min, and naturally cool to room temperature after calcination to obtain a 9wt%-HEAs / CN photocatalyst.

[0100] Step 5: pre-treating the microplastic PET / PLA in 5 mol / L KOH.

[0101] In the 9wt%-HEAs / CN photocatalyst obtained above, the weight ratio of HEAs to CN is 9:100.

[0102] According to the test method for the synergistic hydrogen production of photocatalytic degradation of microplastics described in the application example, the 9wt%-HEAs / CN photocatalyst prepared in this comparative example was used to carry out the synergistic hydrogen production reaction of photocatalytic degradation of microplastics. The hydrogen production rate of microplastic PET under visible light illumination for 4 hours can reach 261.75μmol / g·h, and the hydrogen production rate of microplastic PLA under visible light illumination for 4 hours can reach 333.58μmol / g·h.

[0103] Characterization of the basic CN prepared in the above comparative example and the HEAs / CN photocatalysts prepared in Examples 1-3:

[0104] XRD diffraction pattern: Figure 2As shown, the basic CN obtained in Comparative Example 1 has two obvious diffraction peaks located at 13° and 27°. In the figure, 2θ = 13° is the lattice spacing formed between N atoms and C atoms in a two-dimensional plane, which represents the structural unit of the CN sample, and 2θ = 27° is the characteristic peak of the stacking between layers (002 crystal plane). Compared with the basic CN, the HEAs / CN photocatalysts obtained in the implementation cases all have the same peak shape, but with the increase of HEAs content, the diffraction peaks near 43° and 44° are carefully indexed. The different positions of the diffraction peaks from pure Mn, Fe, Co, Cu, and Ni indicate that these elements may form an alloy.

[0105] TEM and mapping diagram: Figure 1 As shown in (bd), the morphology of the HEAs / CN photocatalyst modified with HEAs still maintains the nanosheet structure of the basic CN. Figure 1 (b) HEAs are relatively evenly dispersed on CN nanosheets. Figure 1 The lattice fringe in (c) is 0.201 nm, corresponding to the (111) crystal plane of HEAs. Figure 1 (d) is the distribution diagram of Mn, Fe, Co, Ni, and Cu elements in the selected area.

[0106] UV-vis spectrum: such as Figure 3 As shown, the absorption band edge of the base CN obtained in Comparative Example 1 is approximately 470nm. After the introduction of HEAs, the HEAs / CN photocatalyst exhibits no significant change in the absorption band compared to the base CN, but its absorbance in the visible light region is significantly enhanced. This phenomenon demonstrates that the HEAs / CN photocatalyst has a significantly improved ability to capture visible light. Under visible light irradiation, the total number of conduction band electrons and valence band holes in the material is greatly increased, thereby enhancing the photocatalyst's hydrogen production capacity.

[0107] Electrochemical performance diagram: Figure 4 (a) shows the transient photocurrent response curves of the basic CN obtained in Comparative Example 1 and the HEAs / CN obtained in Examples 1-3, and tests the responses of the samples to several cycles with and without light irradiation. Compared with the basic CN, the HEAs / CN photocatalyst shows a significantly stronger photocurrent response signal at the moment of light on, indicating that it has a stronger ability to separate and transfer photogenerated charges; Figure 4 As can be seen from the impedance curve in (b), compared with the basic CN, the HEAs / CN photocatalyst has a smaller Nyquist arc radius, indicating that it has a lower photogenerated charge transfer resistance, which is conducive to the rapid transfer and separation of photogenerated carriers and is beneficial to improving the photocatalytic performance of the catalyst.

[0108] Application Examples

[0109] Performance test of photocatalytic hydrogen production: The prepared samples were used in the photocatalytic hydrogen production experiment, and the generated hydrogen was detected using a Beijing Zhongjiao Jinyuan GC-7920 gas chromatograph.

[0110] The testing method was as follows: 30 mg of the photocatalyst (HEAs / CN) was weighed and added to 70 mL of the supernatant solution of PET / PLA pretreated with different KOH concentrations (PET, 18 mg / mL). Before illumination, the solution was sonicated for 30 minutes to disperse the photocatalyst particles, prevent agglomeration, increase the specific surface area, and thus enhance photocatalytic activity. After sonication, the reactor was installed, and then the light source was turned on. Gas chromatography was used for testing every hour. Finally, the experimental data was recorded and analyzed, the power was turned off, and the apparatus was cleaned. The photocatalytic experimental temperature was controlled at 10°C using a circulating cooling system, and the light source used was a 300W xenon lamp with a 420nm cutoff filter (CEL-HXF300, Beijing Zhongjiao Jinyuan).

[0111] The above method was used to test the performance of the HEAs / CN photocatalyst hydrogen production in Comparative Examples 1-2 (basic CN, 9wt%-HEAs / CN-m) and Examples 1-3 of the present invention. The results are shown in FIG. Figure 5 (a). Under the same reaction conditions, CN has basically no obvious hydrogen production effect when there is no composite HEAs, indicating that microplastics have good stability under visible light. After adding the basic CN obtained in Comparative Example 1, the hydrogen production rate under visible light illumination for 4 hours is only 19.64μmol / g·h; after HEAs are introduced into CN, the performance of HEAs / CN photocatalyst hydrogen production is significantly improved, and its hydrogen production rate can reach 361.69μmol / g·h. In addition, we studied the effect of different HEAs contents on the photocatalytic hydrogen production performance of HEAs / CN materials. When the weight ratio of HEAs in the CN material is increased, the hydrogen production rate is greatly improved. The 9wt%-HEAs / CN material exhibits the best photocatalytic hydrogen production performance: 422.96μmol / g·h (the hydrogen production performance of 9wt%-HEAs / CN-m prepared with melamine as a precursor in Comparative Example 2 is only 180.22μmol / g·h); however, when the HEAs content is further increased, the hydrogen production efficiency decreases. When the photocatalyst concentration is the same, the KOH pretreatment concentration is changed. As the KOH concentration increases, the hydrogen production effect is better. Figure 5 (b). In addition, we used 9wt%-HEAs / CN as catalyst to investigate the stability of HEAs / CN photocatalyst. The results are shown in Figure 6Under the same photocatalytic reaction conditions, after 5 cycles of reaction, the photocatalytic hydrogen production performance did not decrease significantly, indicating that the HEAs / CN photocatalyst prepared by us has excellent cyclic stability. The material described in this invention is a HEAs / CN photocatalyst. The introduction of HEAs can broaden the spectral response range, accelerate the transfer and separation of photogenerated electron-hole pairs, and effectively improve its photocatalytic activity, thus having a high performance in photocatalytic removal of microplastics.

[0112] In summary, the photocatalyst of the present invention possesses advantages such as strong light absorption and high photogenerated electron-hole separation efficiency. Experiments have demonstrated that the HEAs / CN photocatalyst is highly effective for visible light photocatalytic hydrogen production from PET and PLA, achieving hydrogen production rates of 422.96 μmol / g·h and 558.72 μmol / g·h over 4 hours, respectively, with excellent cyclic stability.

Claims

1. A method for preparing a non-precious metal HEAs / CN photocatalytic material for degrading microplastics and synergistically producing hydrogen, characterized in that The method comprises the following steps: S1, weighing an appropriate amount of urea into a ceramic crucible with a lid, calcining in air, and cooling to room temperature after calcination to obtain graphite carbon nitride (g-C3N4, CN); S2, weighing appropriate amounts of iron (III) acetylacetonate, cobalt (III) acetylacetonate, nickel (II) acetylacetonate, copper (II) acetylacetonate, and manganese (II) acetylacetonate into a polytetrafluoroethylene-lined hydrothermal reactor, performing a solvothermal reaction at a temperature of 180±20°C for 18-30 hours. After the reaction, the mixture was cooled to room temperature and centrifuged and dried to obtain high entropy alloy nanoparticles (HEANPs) (HEAs); S3, mixing the CN obtained in step S1, the HEAs obtained in step S2, and anhydrous ethanol, sonicating, stirring, and evaporating in a water bath to dryness to obtain a HEAs / CN mixture; the weight ratio of HEAs to CN is 1 to 30:100; S4, placing the HEAs / CN mixture obtained in step S3 in a ceramic crucible with a cover and calcining it under the protection of an inert gas, and naturally cooling it to room temperature after the calcination to obtain a HEAs / CN photocatalyst.

2. The preparation method according to claim 1, wherein: In S1, the calcination temperature is 550±50°C, the calcination time is 3-6h, and the heating rate is 4-7°C / min.

3. The preparation method according to claim 1, wherein: In S2, the concentrations of iron (III) acetylacetonate, cobalt (III) acetylacetonate, nickel (II) acetylacetonate, copper (II) acetylacetonate, and manganese (II) acetylacetonate in the reaction system were 3×10 -3 -7×10 -3 mol / L.

4. The preparation method according to claim 1, wherein: In S3, the dosage ratio of HEAs to ethanol is 0.5-3 mg / mL, and the weight ratio of HEAs to CN is 8-10:100; the ultrasonic time is 10-50 min, the water bath temperature is 50-80° C., and the water bath time is 6-9 h.

5. The preparation method according to claim 1, wherein: In S4, the calcination temperature is 400±50°C, the calcination time is 1-3h, and the heating rate is 3-7°C / min.

6. A non-precious metal HEAs / CN photocatalytic material for degrading microplastics and synergistically producing hydrogen, characterized in that: The material is prepared by the method according to any one of claims 1 to 5.

7. The photocatalytic material according to claim 6, characterized in that The HEAs in the material are MnFeCoNiCu five-element high entropy alloy nanoparticles, and the weight ratio of HEAs to CN is 8:100 to 10:

100.

8. Use of the non-precious metal HEAs / CN photocatalytic material according to any one of claim 6 in the photocatalytic degradation of microplastics and the coordinated production of hydrogen.

9. The use according to claim 8, characterized in that The application includes the following steps: pretreating microplastics in a 0-10 mol / L KOH solution at 40±5°C for 48±8 hours; mixing the pretreated microplastic aqueous solution and the non-precious metal HEAs / CN photocatalytic material in a solvent system under light conditions to achieve synergistic hydrogen production by microplastic degradation.

10. The use according to claim 9, characterized in that The illumination conditions are visible light irradiation, the concentration of HEAs / CN photocatalyst is 0.3-0.5 mg / mL, and the concentration of microplastics is 15-20 mg / mL.

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