An atomic sharing type photocatalysis-photothermal composite material and a preparation method thereof

Abstract

The application discloses an atomic sharing type photocatalysis-photothermal composite material and a preparation method thereof, wherein a bismuth source and a bromine source are dissolved in an organic solvent respectively, mixed after stirring and mixing, and a rare earth ion solution is added, and then a hydrothermal reaction is carried out; a precursor is prepared after centrifugation, washing and drying; then the precursor is added into an aqueous solution of a reducing agent to carry out a bismuth precipitation reduction reaction; and after centrifugation, washing and drying, oxidation annealing is carried out in a muffle furnace in an air atmosphere to obtain Bi2O 3‑x / Bi3O4Br:Er 3+ The atomic sharing type heterojunction of the application has good contact between atoms at the interface, is favorable for promoting charge transmission, reducing interface recombination, and can further improve the related performance of the composite material; has strong SPR absorption in the visible and near-infrared regions; has natural Bi-O tetrahedron sharing, and constructs the atomic sharing type heterojunction with plasmonic resonance and near-infrared light response; and has wide application in degrading organic dyes, antibiotics and heavy metals as a photocatalyst.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of photocatalytic materials, and particularly relates to an atom-shared photocatalysis-photothermal composite material and a preparation method thereof. BACKGROUND

[0002] Semiconductor photocatalysis is a high-efficiency utilization technology of clean energy, and is considered as one of effective means for solving current environmental pollution problems.

[0003] Bi3O4Br is an excellent semiconductor photocatalytic material, and due to a unique layered structure, good optical and photochemical properties, and a suitable energy band structure, it has a good application prospect in the fields of energy conversion and environmental governance. However, due to a narrow light absorption range and high photo-generated carrier recombination, the practical application of Bi3O4Br in photocatalysis is far from satisfactory.

[0004] Rare earth-doped upconversion luminescent materials can convert long-wavelength photon energy into short-wavelength emission, that is, near-infrared light can be absorbed, and visible light and ultraviolet light can be emitted through energy transfer and transition, which provides a new idea for improving the utilization rate of solar energy in photocatalytic materials. Er 3+ is doped into Bi3O4Br to obtain Bi3O4Br:Er 3+ Under near-infrared light excitation, Er 3+ upconversion emission ions emit green light and red light, which is absorbed by Bi3O4Br nanosheets, realizing the degradation of pollutants under near-infrared light and widening the light response range of Bi3O4Br. However, the small absorption cross section of rare earth ions, low upconversion luminescence efficiency, and the difference between the matching of upconversion emission wavelength and semiconductor absorption wavelength make the near-infrared light absorption rate and upconversion conversion efficiency very low, ultimately resulting in generally low photocatalytic efficiency, which affects its practical application.

[0005] In recent years, the construction of heterojunction has become a research hotspot to improve the photocatalytic performance of semiconductor materials. Among them, the heterojunction constructed by coupling plasmonic nanostructures and photocatalytic materials can not only expand the light response range and improve the utilization rate of sunlight by using the surface plasmon resonance (SPR) effect of plasmonic nanostructures, but also effectively suppress the recombination of photo-generated carriers by using the heterojunction interface formed by coupling plasmonic nanostructures and photocatalytic materials, thereby improving the quantum efficiency. More importantly, the localized field regulated by SPR effect can effectively improve the up-conversion luminescence efficiency. However, the SPR absorption of most plasmonic nanostructures is in the visible light region and the light response range is narrow, such as Au noble metal nanoparticles. In addition, there is usually a large lattice mismatch between the photocatalytic material and the plasmonic material, which leads to a large number of defects at the heterojunction interface, which become the recombination center of the matrix carriers and the quenching center of rare earth ion luminescence, thereby affecting the improvement of its performance. In addition, with the expansion of the spectral response range of the photocatalytic material to the near-infrared light region, a part of the solar energy will be converted into heat energy through the photo-thermal effect while the solar energy is converted into chemical energy through the photocatalytic reaction. From the perspective of energy utilization, the infrared radiation with thermal effect is not utilized, which is one of the main reasons for the low efficiency of the photocatalytic reaction.

[0006] Therefore, in order to solve the above problems, the present application provides an atomic sharing type photocatalysis-photothermal composite material and a preparation method thereof. SUMMARY

[0007] In order to solve the above technical problems, the present application designs an atomic sharing type photocatalysis-photothermal composite material and a preparation method thereof. The atomic sharing type heterojunction of the present application has good contact between the atoms at the interface, which is beneficial to promote the charge transport and reduce the interface recombination, and can further improve the related performance of the composite material. The oxygen defect Bi2O 3-x The nanostructure has strong SPR absorption in the visible and near-infrared regions; Bi3O4Br and Bi2O 3-x There is a natural Bi-O tetrahedral sharing, which constructs an atomic sharing type heterojunction with plasmonic resonance and near-infrared light response.

[0008] In order to achieve the above technical effects, the present application is realized by the following technical scheme: an atomic sharing type photocatalysis-photothermal composite material, characterized in that the chemical formula is: Bi2O 3-x / Bi3O4Br:Er 3+ .

[0009] Another object of the present application is to provide a preparation method of an atomic sharing type photocatalysis-photothermal composite material, characterized in that it comprises the following steps:

[0010] Step1, dissolve bismuth source and bromine source in organic solvent respectively, mix after stirring, add aqueous solution containing rare earth ions, adjust pH value, carry out hydrothermal reaction on the obtained aqueous solution, the reaction temperature is 160-200 DEG C, the annealing reaction time is 1-24h, centrifugal, washing, drying to obtain Bi3O4Br:Er 3+ precursor;

[0011] Step2, dissolve the sample obtained in Step1 in the aqueous solution of reducing agent, stir, centrifugal, washing, drying, and then collect;

[0012] Step3, annealing treatment is carried out on the sample obtained in Step2, the reaction temperature is 120-350 DEG C, the annealing reaction time is 1-12h, and the product is obtained.

[0013] Further, the bismuth source in Step1 is one or more of bismuth nitrate pentahydrate, bismuth carbonate and bismuth phosphate; the bromine source is one or more of sodium bromide, cetyltrimethylammonium bromide and ammonium bromide.

[0014] Further, the mass of bismuth source to the volume of organic solvent is 0.5-3g:20-50mL; the mass of bromine source to the volume of organic solvent is 0.5-3g:5-30mL; the molar ratio of bromine element in bromine source to bismuth element in bismuth source is 0.5-5:1.

[0015] Further, the organic solvent in Step1 is one or a mixed solution of mannitol and ethylene glycol.

[0016] Further, the reducing agent in Step2 is one or more of aqueous sodium borohydride solution, ethylene glycol and sodium hypophosphite, and the concentration is 10-20M / L.

[0017] The beneficial effects of the present application are:

[0018] The application discloses an atomic sharing type photocatalysis-photothermal composite material and a preparation method thereof. 3-x / Bi3O4Br:Er 3+ By connecting Bi-O tetrahedron, the atomic sharing type heterojunction interface is formed, the good contact between atoms is formed, the charge transmission is promoted, the interface recombination is reduced, and the photocatalysis performance of the composite material can be further improved; the Bi2O 3-x The SPR effect and the photothermal effect of the nanostructure enhance the light response range and the absorption of the capture capacity, and improve the separation efficiency of photo-generated carriers. BRIEF DESCRIPTION OF DRAWINGS

[0019] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings needed for the description of the embodiments will be briefly introduced as follows. Obviously, the drawings in the following description are only some embodiments of the present application, and for those skilled in the art, other drawings can be obtained without creative labor on the basis of these drawings.

[0020] Figure 1 Bi2O3 / Bi3O4Br:Er prepared for the present application embodiments 1-3 and comparative examples 1, 2 3-x Bi2O3 / Bi3O4Br:Er prepared for the present application embodiments 1-3 and comparative examples 1, 2 3+ Bi2O3 / Bi3O4Br:Er prepared for the present application embodiments 1-3 and comparative examples 1, 2 3+ Bi2O3 / Bi3O4Br:Er prepared for the present application embodiments 1-3 and comparative examples 1, 2

[0021] Figure 2 Bi2O3 / Bi3O4Br:Er prepared for the present application embodiments 1-3 and comparative examples 1, 2 3-x Bi2O3 / Bi3O4Br:Er prepared for the present application embodiments 1-3 and comparative examples 1, 2 3+ Bi2O3 / Bi3O4Br:Er prepared for the present application embodiments 1-3 and comparative examples 1, 2 3+ Bi2O3 / Bi3O4Br:Er prepared for the present application embodiments 1-3 and comparative examples 1, 2

[0022] Figure 3 Bi2O3 / Bi3O4Br:Er prepared for the present application embodiments 1-3 and comparative examples 1, 2 3-x Bi2O3 / Bi3O4Br:Er prepared for the present application embodiments 1-3 and comparative examples 1, 2 3+ Bi2O3 / Bi3O4Br:Er prepared for the present application embodiments 1-3 and comparative examples 1, 2 3+ Bi2O3 / Bi3O4Br:Er prepared for the present application embodiments 1-3 and comparative examples 1, 2

[0023] Figure 4 Bi2O3 / Bi3O4Br:Er prepared for the present application embodiments 1-3 and comparative examples 1, 2 3-x Bi2O3 / Bi3O4Br:Er prepared for the present application embodiments 1-3 and comparative examples 1, 2 3+ Bi2O3 / Bi3O4Br:Er prepared for the present application embodiments 1-3 and comparative examples 1, 2 3+ Bi2O3 / Bi3O4Br:Er prepared for the present application embodiments 1-3 and comparative examples 1, 2 DETAILED DESCRIPTION

[0024] The technical solutions in the embodiments of the present application will be described clearly and completely below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only some embodiments of the present application, and for those skilled in the art, other embodiments can be obtained without creative labor on the basis of these drawings.

[0025] Embodiment 1

[0026] (1) 2 mmol of bismuth nitrate pentahydrate and 2 mmol of sodium bromide were dissolved in 20 mL and 5 mL of a mannitol (0.1 M / L) solution, respectively, stirred for 30 min, and recorded as A solution and B solution, respectively. 0.2 mL of Er(NO3)3(0.1 M / L) was added to the A solution, stirred for 10 min, and then 5 mL of the B solution was added and stirred for another 10 min. Sodium hydroxide (2 M / L) was added to the mixed solution to adjust the pH to 11.5, and after stirring for another 30 min, the liquid was transferred to a 50 mL reactor, placed in an oven at 160°C, and kept for 1 h, and then naturally cooled to room temperature, centrifuged, dried at 70°C, and collected, to obtain Bi3O4Br:Er 3+ precursor.

[0027] (2) 0.5 g of the Bi3O4Br:Er 3+ precursor obtained in step 1 was added to 50 mL of sodium borohydride (C = 10 mM / L) and stirred for 30 min, washed by centrifugation, dried, and collected.

[0028] (3) 0.2 g of the sample in step 1 was annealed in a muffle furnace at 120°C in an air atmosphere for 1 h, to obtain Bi2O 3-x / Bi3O4Br:Er 3+ heterojunction photocatalyst, marked as Bi2O 3-x -BE-10 mM.

[0029] Example 2

[0030] (1) 2 mmol of bismuth carbonate and 5 mmol of cetyltrimethylammonium bromide were dissolved in 20 mL and 30 mL of ethylene glycol (0.1 M / L) solution, respectively, stirred for 30 min, and recorded as A solution and B solution, respectively. 0.2 mL of Er(NO3)3(0.1 M / L) was added to the A solution, stirred for 10 min, and then 5 mL of the B solution was added and stirred for another 10 min. Sodium hydroxide (2 M / L) was added to the mixed solution to adjust the pH to 11.5, and after stirring for another 30 min, the liquid was transferred to a 50 mL reactor, placed in an oven at 180°C, and kept for 12 h, and then naturally cooled to room temperature, centrifuged, dried at 70°C, and collected, to obtain Bi3O4Br:Er 3+ precursor.

[0031] (2) 0.5 g of the Bi3O4Br:Er 3+ precursor obtained in step 1 was added to 50 mL of sodium hypophosphite (C = 15 mM / L) and stirred for 30 min, washed by centrifugation, dried, and collected.

[0032] (3) 0.2 g of the sample from step 1 was annealed in a muffle furnace at 180 °C in air atmosphere for 6 h, to obtain Bi2O 3-x / Bi3O4Br:Er 3+ heterojunction photocatalyst, labeled as Bi2O 3-x - BE - 15 mM.

[0033] Example 3

[0034] (1) 1 mmol of bismuth phosphate and 5 mmol of ammonium bromide were dissolved in 50 mL and 30 mL of a mannitol (0.1 M / L) solution, respectively, stirred for 30 min, and labeled as solution A and solution B, respectively. 0.2 mL of Er(NO3)3(0.1 M / L) was added to solution A, stirred for 10 min, and then 5 mL of solution B was added and stirring was continued for 10 min. Sodium hydroxide (2 M / L) was added to the mixed solution to adjust the pH to 11.5, and after stirring for another 30 min, the above liquid was transferred to a 50 mL reactor, placed in a 200 °C oven, and kept for 24 h, then naturally cooled to room temperature, centrifuged, dried at 70 °C, and collected, to obtain Bi3O4Br:Er 3+ precursor.

[0035] (2) 0.5 g of Bi3O4Br:Er obtained in step 1 was added to 50 mL of ethylene glycol (C = 20 mM / L) and stirred for 30 min, washed by centrifugation, dried, and collected. 3+ precursor, added to 50 mL of ethylene glycol (C = 20 mM / L) and stirred for 30 min, washed by centrifugation, dried, and collected.

[0036] (3) 0.2 g of the sample from step 1 was annealed in a muffle furnace at 300 °C in air atmosphere for 12 h, to obtain Bi2O 3-x / Bi3O4Br:Er 3+ heterojunction photocatalyst, labeled as Bi2O 3-x - BE - 20 mM.

[0037] Comparative Example 1

[0038] 2 mmol of bismuth nitrate pentahydrate and 2 mmol of sodium bromide were dissolved in 20 mL and 5 mL of ethylene glycol (0.1 M / L) solution, respectively, stirred for 3 min, and labeled as solution A and solution B, respectively. 0.2 mL of Er(NO3)3(0.1 M / L) was added to solution A, stirred for 10 min, and then 5 mL of solution B was added and stirring was continued for 10 min. Sodium hydroxide (2 M / L) was added to the mixed solution to adjust the pH to 11.5, and after stirring for another 30 min, the above liquid was transferred to a 50 mL reactor, placed in a 160 °C oven, and kept for 12 h, then naturally cooled to room temperature, centrifuged, dried at 70 °C, and collected, to obtain BE.

[0039] Comparative Example 2

[0040] (1) 2 mmol of bismuth nitrate pentahydrate and 2 mmol of sodium bromide were dissolved in 20 mL and 5 mL of mannitol (0.1 M / L) solution, respectively, and stirred for 30 min, and were recorded as solution A and solution B, respectively. 0.2 mL of Er(NO3)3(0.1 M / L) was added to solution A and stirred for 10 min, and then 5 mL of solution B was added and stirred for another 10 min. Sodium hydroxide (2 M / L) was added to the mixed solution to adjust the pH to 11.5, and after stirring for another 30 min, the above liquid was transferred to a 50 mL reactor and placed in a 160°C oven for 24 h, and then naturally cooled to room temperature, centrifuged, dried at 70°C, and collected, to obtain Bi3O4Br:Er 3+ precursor.

[0041] (2) The Bi3O4Br:Er 3+ precursor obtained in step 1 was mixed with treated commercial Bi powder and stirred for 30 min, and was transferred to a crucible and annealed in a muffle furnace at 350°C in air for 3 h, to obtain Bi2O 3-x / Bi3O4Br:Er 3+ heterojunction photocatalyst, marked as Bi2O 3-x -BE-Primitive.

[0042] photocatalytic activity experiment

[0043] The photocatalytic activity of the samples on BPA degradation was evaluated under a 300W xenon lamp (CEL-LAX500). The reactor used was a customized quartz reactor with a volume of 100 mL, and 20 mg of sample was added to 40 mL of a 20 mg / L bisphenol A solution, which was stirred in the dark for 40 min to ensure that the adsorption-desorption reached equilibrium. 4 mL of the reaction solution was taken out periodically, centrifuged to obtain the supernatant, and the supernatant was analyzed by UV-1800 spectrophotometer.

[0044] photothermal effect test

[0045] The light-heat conversion ability of the samples was evaluated under a 300W xenon lamp (CEL-LAX500) equipped with a filter (λ = 800). The reactor used was a customized crucible with a volume of 3 mL, and 100 mg of sample was added to the crucible, which was placed in light-dark environment for 5 min, and was analyzed periodically by infrared thermal imager (HIKMICRO H10).

[0046] As Figure 1As shown, by comparison with XRD standard card, the samples prepared in Examples 1-3 and Comparative Examples 1 and 2 have no impurity peaks corresponding to the characteristic peaks of Bi2O3 and Bi3O4Br in the X-ray diffraction spectrum, indicating that the samples have high purity, and the Bi2O 3-x -BE heterojunction is successfully prepared; from Figure 2 It can be seen that the absorption spectra of Examples 1-3 and Comparative Example 2 are both widened to the infrared region, and the shared composite heterostructure has greater enhanced absorption intensity; from Figure 3 , Examples 1-3 are higher than Comparative Examples 1 and 2, and the activity of Example 2 is the highest, with a BPA removal rate of more than 70% within 40 min, indicating that the in-situ constructed atomic shared Bi2O 3-x / Bi3O4Br:Er 3+ heterojunction can effectively improve the photocatalytic performance of the composite material compared with Bi3O4Br:Er 3+ and traditional Bi2O 3-x -BE heterojunction. From Figure 4 It can be seen that the near-infrared photothermal performance of Examples 1-3 and Comparative Example 2 is higher than that of Comparative Example 1, and the prepared Bi2O 3-x / Bi3O4Br:Er 3+ heterojunction photocatalyst can effectively utilize near-infrared light and has good photo-thermal conversion effect.

Claims

1. A method for preparing an atom-sharing photocatalytic-photothermal composite material, characterized in that: The following steps are involved: Step 1: Dissolve the bismuth source and bromine source in an organic solvent respectively, stir and mix, add an aqueous solution containing rare earth ions, adjust the pH value, and subject the obtained aqueous solution to a hydrothermal reaction at a reaction temperature of 160-200°C and an annealing reaction time of 1-24h. Centrifuge, wash, and dry to obtain Bi3O4Br:Er 3+ Precursor; Step 2: Dissolve the sample obtained in Step 1 in a reducing agent aqueous solution, stir, centrifuge, wash, dry and collect; Step 3: Anneal the sample obtained in Step 2 at a reaction temperature of 120-350°C and an annealing time of 1-12 hours to obtain a product having the chemical formula Bi2O 3-x / Bi3O4Br:Er 3+ Atom-sharing photocatalytic-photothermal composite materials.

2. The method for preparing an atom-sharing photocatalytic-photothermal composite material according to claim 1, characterized in that: The bismuth source in Step 1 is one or more of bismuth nitrate pentahydrate, bismuth carbonate, and bismuth phosphate; the bromine source is one or more of sodium bromide, hexadecyltrimethylammonium bromide, and ammonium bromide.

3. The method for preparing an atom-sharing photocatalytic-photothermal composite material according to claim 2, characterized in that: The mass ratio of the bismuth source to the volume of the organic solvent is 0.5-3 g:20-50 mL; the mass ratio of the bromine source to the volume of the organic solvent is 0.5-3 g:5-30 mL; and the molar ratio of the bromine element in the bromine source to the bismuth element in the bismuth source is 0.5-5:

1.

4. The method for preparing an atom-sharing photocatalytic-photothermal composite material according to claim 1, characterized in that: The organic solvent described in Step 1 is one of mannitol and ethylene glycol or a mixed solution.

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