CN113019416A - Perovskite nanocrystalline/flaky graphite phase carbon nitride composite material and preparation method thereof - Google Patents
Perovskite nanocrystalline/flaky graphite phase carbon nitride composite material and preparation method thereof Download PDFInfo
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- CN113019416A CN113019416A CN202110280308.6A CN202110280308A CN113019416A CN 113019416 A CN113019416 A CN 113019416A CN 202110280308 A CN202110280308 A CN 202110280308A CN 113019416 A CN113019416 A CN 113019416A
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- JMANVNJQNLATNU-UHFFFAOYSA-N oxalonitrile Chemical compound N#CC#N JMANVNJQNLATNU-UHFFFAOYSA-N 0.000 title claims abstract description 206
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 title claims abstract description 193
- 229910002804 graphite Inorganic materials 0.000 title claims abstract description 189
- 239000010439 graphite Substances 0.000 title claims abstract description 189
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- 238000002360 preparation method Methods 0.000 title claims abstract description 14
- 239000002159 nanocrystal Substances 0.000 claims abstract description 96
- 238000004519 manufacturing process Methods 0.000 claims abstract description 23
- KRKNYBCHXYNGOX-UHFFFAOYSA-N citric acid Chemical compound OC(=O)CC(O)(C(O)=O)CC(O)=O KRKNYBCHXYNGOX-UHFFFAOYSA-N 0.000 claims description 69
- 229910002651 NO3 Inorganic materials 0.000 claims description 51
- NHNBFGGVMKEFGY-UHFFFAOYSA-N Nitrate Chemical compound [O-][N+]([O-])=O NHNBFGGVMKEFGY-UHFFFAOYSA-N 0.000 claims description 51
- 238000001354 calcination Methods 0.000 claims description 44
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- IWOUKMZUPDVPGQ-UHFFFAOYSA-N barium nitrate Chemical compound [Ba+2].[O-][N+]([O-])=O.[O-][N+]([O-])=O IWOUKMZUPDVPGQ-UHFFFAOYSA-N 0.000 claims description 10
- VCJMYUPGQJHHFU-UHFFFAOYSA-N iron(3+);trinitrate Chemical group [Fe+3].[O-][N+]([O-])=O.[O-][N+]([O-])=O.[O-][N+]([O-])=O VCJMYUPGQJHHFU-UHFFFAOYSA-N 0.000 claims description 10
- DHEQXMRUPNDRPG-UHFFFAOYSA-N strontium nitrate Chemical compound [Sr+2].[O-][N+]([O-])=O.[O-][N+]([O-])=O DHEQXMRUPNDRPG-UHFFFAOYSA-N 0.000 claims description 10
- 238000006243 chemical reaction Methods 0.000 claims description 8
- 229910052712 strontium Inorganic materials 0.000 claims description 6
- CIOAGBVUUVVLOB-UHFFFAOYSA-N strontium atom Chemical compound [Sr] CIOAGBVUUVVLOB-UHFFFAOYSA-N 0.000 claims description 6
- NDTZMEKCGHOCBU-UHFFFAOYSA-N strontium;dioxido(dioxo)manganese Chemical compound [Sr+2].[O-][Mn]([O-])(=O)=O NDTZMEKCGHOCBU-UHFFFAOYSA-N 0.000 claims description 6
- 230000000536 complexating effect Effects 0.000 claims description 5
- FYDKNKUEBJQCCN-UHFFFAOYSA-N lanthanum(3+);trinitrate Chemical compound [La+3].[O-][N+]([O-])=O.[O-][N+]([O-])=O.[O-][N+]([O-])=O FYDKNKUEBJQCCN-UHFFFAOYSA-N 0.000 claims description 5
- MIVBAHRSNUNMPP-UHFFFAOYSA-N manganese(2+);dinitrate Chemical group [Mn+2].[O-][N+]([O-])=O.[O-][N+]([O-])=O MIVBAHRSNUNMPP-UHFFFAOYSA-N 0.000 claims description 5
- KBJMLQFLOWQJNF-UHFFFAOYSA-N nickel(ii) nitrate Chemical group [Ni+2].[O-][N+]([O-])=O.[O-][N+]([O-])=O KBJMLQFLOWQJNF-UHFFFAOYSA-N 0.000 claims description 5
- 230000008569 process Effects 0.000 claims description 5
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- ZZCNKSMCIZCVDR-UHFFFAOYSA-N barium(2+);dioxido(dioxo)manganese Chemical compound [Ba+2].[O-][Mn]([O-])(=O)=O ZZCNKSMCIZCVDR-UHFFFAOYSA-N 0.000 claims description 3
- HBAGRTDVSXKKDO-UHFFFAOYSA-N dioxido(dioxo)manganese lanthanum(3+) Chemical compound [La+3].[La+3].[O-][Mn]([O-])(=O)=O.[O-][Mn]([O-])(=O)=O.[O-][Mn]([O-])(=O)=O HBAGRTDVSXKKDO-UHFFFAOYSA-N 0.000 claims description 3
- AJCDFVKYMIUXCR-UHFFFAOYSA-N oxobarium;oxo(oxoferriooxy)iron Chemical compound [Ba]=O.O=[Fe]O[Fe]=O.O=[Fe]O[Fe]=O.O=[Fe]O[Fe]=O.O=[Fe]O[Fe]=O.O=[Fe]O[Fe]=O.O=[Fe]O[Fe]=O AJCDFVKYMIUXCR-UHFFFAOYSA-N 0.000 claims description 3
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- 229920003171 Poly (ethylene oxide) Polymers 0.000 description 1
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N Silicium dioxide Chemical compound O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 description 1
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- PYWVYCXTNDRMGF-UHFFFAOYSA-N rhodamine B Chemical compound [Cl-].C=12C=CC(=[N+](CC)CC)C=C2OC2=CC(N(CC)CC)=CC=C2C=1C1=CC=CC=C1C(O)=O PYWVYCXTNDRMGF-UHFFFAOYSA-N 0.000 description 1
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
- B01J27/00—Catalysts comprising the elements or compounds of halogens, sulfur, selenium, tellurium, phosphorus or nitrogen; Catalysts comprising carbon compounds
- B01J27/24—Nitrogen compounds
-
- B01J35/39—
-
- C—CHEMISTRY; METALLURGY
- C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F1/00—Treatment of water, waste water, or sewage
- C02F1/30—Treatment of water, waste water, or sewage by irradiation
-
- C—CHEMISTRY; METALLURGY
- C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F2101/00—Nature of the contaminant
- C02F2101/30—Organic compounds
- C02F2101/40—Organic compounds containing sulfur
-
- C—CHEMISTRY; METALLURGY
- C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F2305/00—Use of specific compounds during water treatment
- C02F2305/10—Photocatalysts
Abstract
The invention provides a perovskite nanocrystal/flake graphite phase carbon nitride composite material and a preparation method thereof, belonging to the field of composite photocatalyst materials. The invention adopts the flaky graphite phase carbon nitride material as a carrier material, and the two-dimensional plane structure of the material is beneficial to the transmission of electrons, thereby effectively preventing the recombination of electron-hole pairs in the material; meanwhile, the agglomeration of perovskite nano-crystals is avoided, the perovskite nano-crystals can still have higher dispersion degree on the surface of the perovskite nano-crystals under the small particle size, and the transfer of photogenerated electrons in the semiconductor perovskite photocatalyst is promoted, so that the separation efficiency of photogenerated carriers is improved, and the composite material shows good photocatalytic activity. The perovskite nanocrystalline/flaky graphite phase carbon nitride composite material provided by the invention has good photocatalytic activity, not only has good photocatalytic degradation effect on organic dye, but also has higher hydrogen production rate when photocatalytic water decomposition hydrogen production is carried out.
Description
Technical Field
The invention belongs to the field of composite photocatalyst materials, and particularly relates to a perovskite nanocrystal/flake graphite phase carbon nitride composite material and a preparation method thereof.
Background
Currently, the catalytic efficiency of photocatalytic reaction using single graphite phase carbon nitride or single perovskite material is still at a low level, so although researchers have described that composite photocatalytic materials are prepared by combining graphite phase carbon nitride and perovskite nanocrystals, the typical ABO is still used3The perovskite nanocrystals are easy to agglomerate and not easy to disperse, the composite catalyst is prepared by loading graphite-phase carbon nitride on the surface of the perovskite nanocrystals in the prior art, for example, LaFeO in the composite catalyst is recorded in the performance analysis of the perovskite-carbon nitride composite material and the application of the composite material in the treatment of wastewater by light-Fenton3At a theoretical mass of 90% (i.e. LaFeO)3/g-C3N4The catalyst has the best activity, and the degradation rate activity curve chart of the catalyst on rhodamine B tends to be flat after reaching 95 percent, namely the highest degradation rate can reach 95 percent. Meanwhile, researches show that XRD detection results show that the perovskite/carbon nitride composite catalyst has more miscellaneous peaks and less prominent characteristic peaks, and the formation of a perovskite structure is influenced by the existence of N atoms in carbon nitride, so that the improvement of the photocatalytic performance of the composite material is limited.
Disclosure of Invention
The invention aims to provide a perovskite nanocrystal/flake graphite phase carbon nitride composite material and a preparation method thereof, wherein the composite material shows good photocatalytic activity.
In order to achieve the above object, the present invention provides the following technical solutions:
the invention provides a perovskite nanocrystalline/flake graphite phase carbon nitride composite material, which comprises flake graphite phase carbon nitride and perovskite nanocrystalline distributed on the surface of the flake graphite phase carbon nitride; the mass content of the perovskite nanocrystalline in the perovskite nanocrystalline/flake graphite phase carbon nitride composite material is 11% -33%; the average grain size of the perovskite nanocrystal is 70-200 nm.
Preferably, the perovskite nanocrystal comprises one of lanthanum manganate nanocrystal, strontium manganate nanocrystal, barium manganate nanocrystal, lanthanum ferrite nanocrystal, strontium ferrite nanocrystal, barium ferrite nanocrystal, lanthanum nickelate nanocrystal, strontium nickelate nanocrystal and barium nickelate nanocrystal.
The invention also provides a preparation method of the perovskite nanocrystalline/flaky graphite phase carbon nitride composite material, which comprises the following steps:
(1) providing a flaky graphite phase carbon nitride suspension;
(2) sequentially adding composite nitrate, citric acid and alkylphenol ethoxylates into the flaky graphite-phase carbon nitride suspension in the step (1) for a complexing reaction to obtain a perovskite nanocrystalline/flaky graphite-phase carbon nitride precursor solution;
(3) sequentially aging and drying the perovskite nanocrystalline/flaky graphite phase carbon nitride precursor liquid obtained in the step (2) to obtain perovskite nanocrystalline/flaky graphite phase carbon nitride precursor xerogel;
(4) and (4) sequentially carrying out primary calcination and secondary calcination treatment on the perovskite nanocrystalline/flaky graphite phase carbon nitride precursor xerogel obtained in the step (3) to obtain the perovskite nanocrystalline/flaky graphite phase carbon nitride composite material.
Preferably, the complex nitrate in the step (2) comprises group A nitrate and group B nitrate; the nitrate in the group A is lanthanum nitrate, strontium nitrate or barium nitrate; the nitrate in the group B is manganese nitrate, ferric nitrate or nickel nitrate.
Preferably, the mass ratio of the composite nitrate to the graphite flake-phase carbon nitride in the step (2) is 1: (0.28-3.30).
Preferably, the mass ratio of the citric acid to the composite nitrate in the step (2) is (1.5-2.2): 1.
preferably, in the step (2), the mass of the alkylphenol polyoxyethylene ether is 2-2.8% of that of the composite nitrate.
Preferably, the temperature for aging in the step (3) is 50-70 ℃, and the time for aging is 8-24 h.
Preferably, the temperature of the first calcination in the step (4) is 400-500 ℃, and the time of the first calcination is 2-4 h.
Preferably, the temperature of the second calcination in the step (4) is 550-650 ℃, and the time of the second calcination is 2-4 h.
The invention provides a perovskite nanocrystalline/flake graphite phase carbon nitride composite material, which comprises flake graphite phase carbon nitride and perovskite nanocrystalline distributed on the surface of the flake graphite phase carbon nitride; the mass content of the perovskite nanocrystalline in the perovskite nanocrystalline/flake graphite phase carbon nitride composite material is 11% -33%; the average grain size of the perovskite nanocrystal is 70-200 nm. The invention adopts the flaky graphite phase carbon nitride material as a carrier material, and the two-dimensional plane structure of the material is beneficial to the transmission of electrons, thereby effectively preventing the recombination of electron-hole pairs in the material; meanwhile, the agglomeration of perovskite nano-crystals is avoided, the perovskite nano-crystals can still have higher dispersion degree on the surface of the perovskite nano-crystals under the small particle size, and the transfer of photogenerated electrons in the semiconductor perovskite photocatalyst is promoted, so that the separation efficiency of photogenerated carriers is improved, and the composite material shows good photocatalytic activity.
The results of the examples show that the perovskite nanocrystalline/flake graphite phase carbon nitride composite material provided by the invention has good photocatalytic degradation effect on organic dyes, the degradation rate of the perovskite nanocrystalline/flake graphite phase carbon nitride composite material on methylene blue can reach about 99.9% within 3.5 hours, and the degradation rates are respectively 1.5 times and 2.8 times of the degradation rates of single flake graphite phase carbon nitride and single perovskite; meanwhile, the hydrogen production rate of the perovskite nanocrystalline/flake graphite phase carbon nitride composite material provided by the invention can be as high as 1189.49-1329.54 mu mol h when the hydrogen is produced by photocatalytic decomposition of water-1g-1。
Drawings
FIG. 1 shows SrMnO in example 1 of the present invention3Scanning electron microscope images of the perovskite nanocrystalline/flake graphite phase carbon nitride composite material;
FIG. 2 shows LaFeO in example 2 of the present invention3An X-ray diffraction pattern of the perovskite nanocrystalline/graphite flake phase carbon nitride composite;
FIG. 3 shows LaFeO in example 2 of the present invention3Scanning electron microscope images of the perovskite nanocrystalline/flake graphite phase carbon nitride composite material;
FIG. 4 shows LaFeO in example 2 of the present invention3A photocatalytic decomposition curve of the perovskite nanocrystalline/flake graphite phase carbon nitride composite material for degrading dye methylene blue;
FIG. 5 shows BaNiO in example 3 of the present invention3Scanning electron microscope images of the perovskite nanocrystalline/flake graphite phase carbon nitride composite material;
FIG. 6 is a graph showing hydrogen production rate curves of three perovskite nanocrystalline/flake graphite phase carbon nitride composite materials prepared in examples 1 to 3 according to the present invention, in which CNNS is a carbon nitride nanosheet, LFO is a pure lanthanum ferrite LaFeO3SMO/CNNS is SrMnO of example 13The perovskite nanocrystal/graphite flake phase carbon nitride composite, LFO/CNNS, is the LaFeO of example 23Perovskite nanocrystalline/graphite flake phase carbon nitride composite, BNO/CNNS being BaNiO of example 33Perovskite nanocrystal/graphite flake phase carbon nitride composites).
Detailed Description
The invention provides a perovskite nanocrystalline/flake graphite phase carbon nitride composite material, which comprises flake graphite phase carbon nitride and perovskite nanocrystalline distributed on the surface of the flake graphite phase carbon nitride; the mass content of the perovskite nanocrystalline in the perovskite nanocrystalline/flake graphite phase carbon nitride composite material is 11% -33%; the average grain size of the perovskite nanocrystal is 70-200 nm.
The perovskite nanocrystalline/flaky graphite phase carbon nitride composite material provided by the invention comprises flaky graphite phase carbon nitride. The invention adopts the flaky graphite phase carbon nitride material, the two-dimensional plane structure of which is beneficial to the transmission of electrons, can effectively prevent the recombination of electron-hole pairs in the material and is more beneficial to improving the photocatalytic activity of the perovskite nanocrystalline/flaky graphite phase carbon nitride composite material.
In the invention, the thickness of the lamellar layer of the flake graphite phase carbon nitride is preferably 10-50 nm, more preferably 15-45 nm, and most preferably 20-40 nm. The invention can ensure that good photocatalytic activity is obtained after the final loaded perovskite nanocrystalline by controlling the thickness of the flake graphite phase carbon nitride.
The perovskite nanocrystalline/flake graphite phase carbon nitride composite material provided by the invention comprises perovskite nanocrystalline distributed on the surface of flake graphite phase carbon nitride. The invention takes the flake graphite phase carbon nitride as a carrier, can effectively improve the dispersion degree of the perovskite nano crystal, and promotes the transfer of photogenerated electrons in the semiconductor perovskite photocatalyst, thereby improving the separation efficiency of the photogenerated carriers and leading the composite material to obtain good photocatalytic activity.
In the present invention, the perovskite nanocrystal preferably includes one of lanthanum manganate nanocrystal, strontium manganate nanocrystal, barium manganate nanocrystal, lanthanum ferrite nanocrystal, strontium ferrite nanocrystal, barium ferrite nanocrystal, lanthanum nickelate nanocrystal, strontium nickelate nanocrystal, and barium nickelate nanocrystal. The perovskite nanocrystalline in the form of the composite metal oxide can form an active site in a C-O-metal bond form with carbon nitride, so that the catalytic activity of the composite material is improved, the decomposition of a photocatalytic substrate is promoted more quickly, and the photocatalytic efficiency is improved.
In the invention, the mass content of the perovskite nanocrystals in the perovskite nanocrystal/flake graphite phase carbon nitride composite material is 11-33%, preferably 13-30%, more preferably 15-28%, and most preferably 20-25%. According to the invention, by controlling the mass content of the perovskite nanocrystals in the perovskite nanocrystal/flake graphite phase carbon nitride composite material, namely introducing less perovskite nanocrystals into the flake graphite phase carbon nitride, the aggregation of perovskite nanoparticles can be reduced, and the perovskite nanoparticles can be more uniformly dispersed on the surface of the flake graphite phase carbon nitride, so that the composite material with higher surface area and more active sites can be more favorably obtained, and the photocatalytic activity of the composite material can be effectively improved.
The perovskite nanocrystal/flake graphite phase carbon nitride composite material provided by the invention has the average crystal grain size of 70-200 nm, preferably 75-150 nm, and more preferably 80-120 nm. According to the invention, by controlling the average particle size of the perovskite nano-crystal, a larger contact area can be obtained between the perovskite nano-crystal and the flake graphite phase carbon nitride, so that a larger bonding force can be obtained on the surface of the graphite phase carbon nitride, and the composite material has higher stability; meanwhile, in the grain size range, the perovskite nanocrystalline has larger specific surface area and provides more active sites, so that the photocatalytic activity of the composite material is effectively improved.
The perovskite nanocrystalline/flaky graphite phase carbon nitride composite material provided by the invention has good photocatalytic activity, not only has good photocatalytic degradation effect on organic dye, but also has higher hydrogen production rate when photocatalytic water decomposition hydrogen production is carried out.
The invention also provides a preparation method of the perovskite nanocrystalline/flaky graphite phase carbon nitride composite material, which comprises the following steps:
(1) providing a flaky graphite phase carbon nitride suspension;
(2) sequentially adding composite nitrate, citric acid and alkylphenol ethoxylates into the flaky graphite-phase carbon nitride suspension in the step (1) for a complexing reaction to obtain a perovskite nanocrystalline/flaky graphite-phase carbon nitride precursor solution;
(3) sequentially aging and drying the perovskite nanocrystalline/flaky graphite phase carbon nitride precursor liquid obtained in the step (2) to obtain perovskite nanocrystalline/flaky graphite phase carbon nitride precursor xerogel;
(4) and (4) sequentially carrying out primary calcination and secondary calcination treatment on the perovskite nanocrystalline/flaky graphite phase carbon nitride precursor xerogel obtained in the step (3) to obtain the perovskite/flaky graphite phase carbon nitride composite material.
The invention provides a flaky graphite phase carbon nitride suspension.
In the present invention, the graphite flake-phase carbon nitride is preferably produced by the production method disclosed in the patent application No. 202010096059.0.
In the present invention, the solvent of the graphite flake-phase carbon nitride suspension is preferably distilled water; the concentration of the flake graphite phase carbon nitride suspension is preferably 2.43-2.54 mg/mL, and more preferably 2.45-2.50 mg/mL. According to the invention, through controlling the concentration of the flaky graphite phase carbon nitride suspension, the flaky graphite phase carbon nitride in the suspension can be prevented from settling, so that the effective load of the subsequent perovskite nano-crystal on the surface of the perovskite nano-crystal can be ensured.
The operation of preparing the graphite flake-phase carbon nitride suspension is not particularly limited in the present invention, and the operation of dispersing a solid in a liquid solvent, which is well known in the art, may be employed.
After the flaky graphite phase carbon nitride suspension is obtained, the invention sequentially adds the composite nitrate, citric acid and alkylphenol ethoxylates into the flaky graphite phase carbon nitride suspension for complex reaction to obtain the perovskite nanocrystalline/flaky graphite phase carbon nitride precursor solution.
In the present invention, the mass ratio of the complex nitrate to the graphite flake-phase carbon nitride is preferably 1: (0.28 to 3.30), more preferably 1: (0.50 to 3.0), most preferably 1: (1.0-2.0). According to the invention, by adjusting the mass ratio of the composite nitrate to the flake graphite phase carbon nitride, the finally obtained perovskite nano-crystal can be uniformly deposited on the surface of the flake graphite phase carbon nitride, so that the expected load capacity is reached, the agglomeration caused by the formation of too many perovskite nano-crystals is avoided, and the insufficient obtainment of sufficient active sites caused by the formation of less perovskite nano-crystals is avoided.
In the present invention, the complex nitrate preferably includes group a nitrate and group b nitrate; the nitrate in the group A is preferably lanthanum nitrate, strontium nitrate or barium nitrate; the nitrate in group B is preferably manganese nitrate, ferric nitrate or nickel nitrate.
In the present invention, the ratio of the amounts of the species of group a nitrate and group b nitrate is preferably 1: (0.8 to 1.6), more preferably 1: (0.9 to 1.3), most preferably 1: (1.0-1.2). According to the invention, the ratio of the amounts of the A group nitrate and the B group nitrate is controlled, so that the perovskite nano-crystal with high crystallinity can be obtained more favorably.
The invention preferably carries out ultrasonic treatment after adding the composite nitrate; the time of ultrasonic treatment is preferably 50-60 min, and more preferably 55-60 min. By adopting ultrasonic treatment, the composite nitrate can be more uniformly dispersed into the flake graphite phase carbon nitride suspension, so that the composite nitrate is fully contacted with the flake graphite phase carbon nitride in the suspension, and the subsequent complexing product can be more favorably and uniformly loaded on the surface of the flake graphite phase carbon nitride.
In the invention, the mass ratio of the citric acid to the composite nitrate is preferably (1.5-2.2): 1, more preferably (1.8 to 2.1): 1, most preferably (1.95 to 2.05). According to the invention, by controlling the mass ratio of citric acid to the composite nitrate and utilizing the complexing effect of citric acid, metal ions in the composite nitrate can be fully complexed, so that the composite metal ions are uniformly attached to the surface of the flake graphite phase carbon nitride in a complex form.
In the invention, the mass of the alkylphenol polyoxyethylene is preferably 2-2.8%, more preferably 2.2-2.6%, and most preferably 2.3-2.5% of the mass of the composite nitrate. According to the invention, by adding alkylphenol ethoxylates and controlling the addition amount of the alkylphenol ethoxylates, the components in the mixed solution can be in a more uniform dispersion form, and sedimentation is avoided; meanwhile, the wettability of the surface of the flake graphite phase carbon nitride is improved, the bonding strength of the flake graphite phase carbon nitride and the perovskite nano crystal is improved, the finally formed perovskite nano crystal/flake graphite phase carbon nitride composite material is higher in stability, and the catalytic performance of the composite material is improved.
In the invention, the pH value of the complexation reaction is preferably 9-11, and more preferably 10-11; the pH value is preferably adjusted by dropwise adding ammonia water. According to the invention, the pH value of the complexation reaction is adjusted to be within the alkaline range of 9-11, so that the complexed metal citrate can be uniformly dispersed in the system, and the settlement of the metal citrate can be avoided.
After obtaining the perovskite nanocrystal/flake graphite phase carbon nitride precursor liquid, the invention sequentially ages and dries the perovskite nanocrystal/flake graphite phase carbon nitride precursor liquid to obtain the perovskite nanocrystal/flake graphite phase carbon nitride precursor xerogel.
In the invention, the aging temperature is preferably 50-70 ℃, more preferably 55-65 ℃, and most preferably 57-60 ℃; the aging time is preferably 8-24 h, more preferably 10-22 h, and most preferably 15-20 h. According to the invention, through aging for a long time at a certain temperature, the metal citrate in the perovskite nanocrystalline/flaky graphite phase carbon nitride precursor liquid can be slowly aggregated to form a gel system with a three-dimensional network structure, the gel system has rich porous structure, is more beneficial to obtaining a perovskite nanocrystalline/flaky graphite phase carbon nitride composite material with a large specific surface area, and has multiple active sites and excellent photocatalytic activity.
In the present invention, the aging is preferably carried out in a constant-temperature water bath. According to the invention, by aging in a constant-temperature water bath, solvent evaporation caused by long-time aging can be avoided, and the precipitation of aggregated particles in gel is prevented, so that the uniformity of an aged gel system is ensured, and the uniform adhesion of perovskite nanocrystals on the surface of flake graphite phase carbon nitride is further realized.
In the invention, the drying temperature is preferably 70-85 ℃, more preferably 75-80 ℃, and most preferably 80 ℃. The invention can regulate and control the evaporation rate of the solvent by controlling the drying temperature, thereby ensuring that the formed xerogel system is uniform.
The drying time is not particularly limited, and the solvent in the material can be completely volatilized according to the actual drying temperature. In the present invention, the drying device is preferably a drying oven.
After obtaining the perovskite nanocrystalline/flaky graphite phase carbon nitride precursor xerogel, the perovskite nanocrystalline/flaky graphite phase carbon nitride precursor xerogel is sequentially subjected to primary calcination and secondary calcination treatment to obtain the perovskite/flaky graphite phase carbon nitride composite material.
In the present invention, the atmosphere of the first calcination is preferably air. According to the invention, the citric acid can be subjected to oxidative decomposition in the air by carrying out primary calcination in the air, the formed gas can effectively escape from the system and be decomposed by nitrate, and perovskite type oxide is preliminarily formed.
In the invention, the temperature of the first calcination is preferably 400-500 ℃, more preferably 420-480 ℃, and most preferably 450-460 ℃; the time for the first calcination is preferably 2-4 h, more preferably 2.5-3.5 h, and most preferably 2.8-3.2 h. The invention can make the decomposition of citric acid and the oxidation of the composite metal compound more sufficient by controlling the temperature and time of the first calcination.
In the invention, the rate of heating to the first calcination is preferably 8-12 ℃/min, and more preferably 9-11 ℃/min.
In the present invention, the cooling mode after the completion of the first calcination is preferably furnace-cooled to room temperature.
In the present invention, the atmosphere of the second calcination is preferably vacuum. The invention can effectively prevent carbon nitride from being oxidized by carrying out secondary calcination in vacuum, so that the composite metal oxide is crystallized to form perovskite nano-crystals.
In the invention, the temperature of the second calcination is preferably 550-650 ℃, more preferably 570-630 ℃, and most preferably 590-610 ℃; the time of the second calcination is preferably 2 to 4 hours, more preferably 2.5 to 3.5 hours, and most preferably 2.8 to 3.2 hours. According to the invention, the perovskite/flaky graphite phase carbon nitride composite material with fine and uniformly distributed crystal grains can be obtained by controlling the temperature and time of the second calcination and avoiding the coarsening of the perovskite nanocrystal.
In the invention, the rate of heating to the second calcination is preferably 8-12 ℃/min, and more preferably 9-11 ℃/min.
In the present invention, the cooling mode after the completion of the second calcination is preferably furnace-cooled to room temperature.
The equipment for the first calcination and the second calcination is not particularly limited in the present invention, and calcination equipment known to those skilled in the art may be used.
According to the preparation method of the perovskite nanocrystalline/flake graphite phase carbon nitride composite material, perovskite nanocrystalline is directly loaded on the surface of the formed flake graphite phase carbon nitride, the perovskite nanocrystalline deposited and crystallized on the surface of the flake graphite phase carbon nitride can be guaranteed to be uniformly distributed, and the perovskite nanocrystalline is stable in crystal structure, high in crystallinity and good in oxidation reduction, so that the perovskite nanocrystalline/flake graphite phase carbon nitride composite material with higher catalytic activity can be obtained by loading a small amount of perovskite nanocrystalline when graphite phase carbon nitride is used as a carrier, and the preparation method is simple in process, low in cost and easy to control the reaction process.
The technical solution of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. It is to be understood that the described embodiments are merely exemplary of the invention, and not restrictive of the full scope of the invention. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
Example 1
The preparation method of the perovskite nanocrystal/flake graphite phase carbon nitride composite material comprises the following specific steps:
(1) providing a flaky graphite phase carbon nitride suspension; the flaky graphite-phase carbon nitride is prepared by the preparation method of specification example 2 in the patent with application number of '202010096059.0', and the specific process is as follows:
weighing 20g of melamine, putting the melamine into 100mL of glacial acetic acid with the purity of more than 99.5 wt%, stirring for 24h at 25 ℃ by using a magnetic stirrer, filtering the obtained system after stopping stirring, washing the obtained solid material to be neutral by using deionized water, then putting the solid material into a drying oven, drying at the constant temperature of 50 ℃, transferring the solid material into a crucible after drying, heating the solid material from room temperature to 520 ℃ at the heating rate of 10 ℃/min in the air atmosphere, carrying out heat preservation and calcination for 4h, and cooling the solid material to the room temperature along with the furnace; heating the graphite to 550 ℃ from room temperature at the heating rate of 2 ℃/min in the air atmosphere, carrying out heat preservation and calcination for 3h, cooling the graphite to room temperature along with the furnace, taking out the obtained product, and grinding the product to obtain the flake graphite phase carbon nitride;
762mg of the graphite flake-phase carbon nitride prepared above was added to 300mL of distilled water and dispersed to obtain a graphite flake-phase carbon nitride suspension of 2.54 mg/mL.
(2) Firstly, adding a composite nitrate consisting of strontium nitrate and manganese nitrate with the mass ratio of 1:1.4 into the flaky graphite-phase carbon nitride suspension in the step (1), wherein the mass ratio of the composite nitrate to the flaky graphite-phase carbon nitride is 1: 3.29; ultrasonically dispersing for 60min, and then adding citric acid and alkylphenol ethoxylates, wherein the mass ratio of the citric acid to the composite nitrate is 2:1, and the mass of the alkylphenol ethoxylates is 2.5 percent of the mass of the composite nitrate; after citric acid and alkylphenol ethoxylates are completely dissolved, ammonia water is dripped into the solution to adjust the pH value to 9, and a complex reaction is carried out to obtain the perovskite nanocrystal/flaky graphite phase carbon nitride precursor solution (wherein the actual mass of each raw material is 105.8mg of strontium nitrate, 125.5mg of manganese nitrate, 462.6mg of citric acid and 5.8mg of alkylphenol ethoxylates (OP-10)).
(3) And (3) ageing the perovskite nanocrystalline/flaky graphite phase carbon nitride precursor liquid obtained in the step (2) in a constant-temperature water bath at 60 ℃ for 16h, and then drying the precursor liquid in a drying oven at 80 ℃ to obtain the perovskite nanocrystalline/flaky graphite phase carbon nitride precursor xerogel.
(4) Heating the perovskite nanocrystalline/flaky graphite phase carbon nitride precursor xerogel obtained in the step (3) at 10 ℃/min in the air atmosphere, heating to 450 ℃ for first calcination for 4h, and cooling to room temperature along with the furnace; and then heating the mixture in a vacuum atmosphere at a temperature of 10 ℃/min, heating the mixture to 550 ℃ for secondary calcination treatment, wherein the calcination time is 4h, and cooling the mixture to room temperature along with the furnace to obtain the perovskite nanocrystal/flake graphite phase carbon nitride composite material.
The perovskite nanocrystal/flake graphite phase carbon nitride composite material provided by the embodiment comprises flake graphite phase carbon nitride and SrMnO distributed on the surface of the flake graphite phase carbon nitride3Perovskite nanocrystalline composition; and the strontium manganate perovskite nanocrystal is in SrMnO3Substances in perovskite nanocrystalline/flaky graphite phase carbon nitride composite materialThe amount percentage was 11%. As shown in the SEM image of FIG. 1, SrMnO prepared in this example3The perovskite nanocrystalline/flaky graphite phase carbon nitride composite material has a flaky structure, nano strontium manganate particles are uniformly distributed on flaky graphite phase carbon nitride, and the average grain size of the nano strontium manganate particles is about 70 nm.
Example 2
The preparation method of the perovskite nanocrystal/flake graphite phase carbon nitride composite material comprises the following specific steps:
(1) providing a flaky graphite phase carbon nitride suspension; the method for preparing the graphite-phase flaky carbon nitride in this example is the same as that in step (1) of example 1 of the present invention;
485.4mg of the graphite flake-phase carbon nitride prepared above was added to 200mL of distilled water and dispersed to give a graphite flake-phase carbon nitride suspension of 2.43 mg/mL.
(2) Firstly adding a composite nitrate consisting of lanthanum nitrate and ferric nitrate with the mass ratio of 1:1.25 into the flaky graphite-phase carbon nitride suspension in the step (1), wherein the mass ratio of the composite nitrate to the flaky graphite-phase carbon nitride is 1: 1.15; ultrasonically dispersing for 60min, and then adding citric acid and alkylphenol ethoxylates, wherein the mass ratio of the citric acid to the composite nitrate is 1.72:1, and the mass of the alkylphenol ethoxylates is 2.16% of that of the composite nitrate; after citric acid and alkylphenol ethoxylates are completely dissolved, ammonia water is dripped into the solution to adjust the pH value to 10, and a complex reaction is carried out to obtain the perovskite nanocrystal/flaky graphite phase carbon nitride precursor solution (wherein the actual mass of each raw material is 216.5mg of lanthanum nitrate, 202mg of ferric nitrate, 837mg of citric acid, and 10.5mg of alkylphenol ethoxylates (OP-10)).
(3) And (3) ageing the perovskite nanocrystalline/flaky graphite phase carbon nitride precursor liquid obtained in the step (2) in a constant-temperature water bath at 50 ℃ for 24 hours, and then drying the precursor liquid in a drying oven at 80 ℃ to obtain the perovskite nanocrystalline/flaky graphite phase carbon nitride precursor xerogel.
(4) Heating the perovskite nanocrystalline/flaky graphite phase carbon nitride precursor xerogel obtained in the step (3) at 10 ℃/min in the air atmosphere, heating to 400 ℃ for first calcination for 3h, and cooling to room temperature along with the furnace; and then heating the mixture in a vacuum atmosphere at a temperature of 10 ℃/min, heating the mixture to 600 ℃ for carrying out secondary calcination treatment, wherein the calcination time is 3h, and cooling the mixture to room temperature along with the furnace to obtain the perovskite nanocrystal/flake graphite phase carbon nitride composite material.
The perovskite nanocrystal/flake graphite phase carbon nitride composite material provided by the embodiment comprises flake graphite phase carbon nitride and LaFeO distributed on the surface of the flake graphite phase carbon nitride3Perovskite nanocrystalline composition, and LaFeO3Perovskite nanocrystalline in LaFeO3The mass percentage of the perovskite nanocrystalline/flaky graphite phase carbon nitride composite material is 20%.
XRD of FIG. 2 shows that LaFeO prepared in this example3The perovskite nanocrystalline/flake graphite phase carbon nitride composite material is characterized in that lanthanum ferrite and flake graphite phase carbon nitride coexist, and a peak at the 2 theta-27.6 degrees is attributed to a carbon nitride (002) crystal face (JCPDS 87-1526); moreover, the composite material also shows a characteristic peak of lanthanum ferrite (JCPDS 87-1526), which shows that the lanthanum ferrite is successfully compounded with the flaky graphite phase carbon nitride and the crystal structure of the flaky graphite phase carbon nitride is not changed by adding the lanthanum ferrite.
As can be seen from FIG. 3, LaFeO prepared under the technical scheme of this example 23The perovskite nanocrystalline/flaky graphite phase carbon nitride composite material has a flaky structure, lanthanum ferrite particles are uniformly distributed on the flaky graphite phase carbon nitride, and the average grain size of the lanthanum ferrite particles is about 120 nm.
And (3) testing the performance of photocatalytic degradation of methylene blue:
LaFeO prepared in this example 2 was used as a target contaminant with a xenon lamp as the light source and methylene blue as the target contaminant3The perovskite nanocrystalline/flake graphite phase carbon nitride composite material is used as a catalyst for photocatalytic degradation, and is combined with single flake graphite phase carbon nitride and single LaFeO3The perovskite nanocrystalline photocatalysis performance is compared, and the method comprises the following specific steps:
LaFeO prepared in example 2 was taken3Adding 25mg of perovskite nanocrystalline/flake graphite phase carbon nitride composite material into 50mL of methylene blue solution (10mg/L), and magnetically treating in darkStirring for 30min, starting a light source after the adsorption-desorption balance is achieved, and carrying out photocatalytic degradation at room temperature, wherein the distance between the light source and the surface of the methylene blue solution is about 25 cm; in the photocatalytic degradation process, 4mL of methylene blue solution is taken every 30min, and the supernatant is obtained by centrifugation; and measuring the absorption wavelength of the target pollutants degraded at different time by using an ultraviolet-visible spectrophotometer, and calibrating the concentration of the supernatant by using the absorbance value at the maximum wavelength.
FIG. 4 LaFeO prepared in example 2 of the present invention3The photocatalytic decomposition curve of the perovskite nanocrystalline/flake graphite phase carbon nitride composite material for degrading the dye methylene blue is shown in figure 4, and the composite material is more than single flake graphite phase carbon nitride and single LaFeO3The perovskite catalyst has higher catalytic activity, has good photocatalytic degradation effect on organic dye, has the degradation rate on methylene blue within 3.5h of about 99.9 percent, has the photocatalytic efficiency which is 1.5 times that of single flake graphite phase carbon nitride and is single LaFeO32.8 times that of perovskite.
Example 3
The preparation method of the perovskite nanocrystal/flake graphite phase carbon nitride composite material comprises the following specific steps:
(1) providing a flaky graphite phase carbon nitride suspension; the method for preparing the graphite-phase flaky carbon nitride in this example is the same as that in step (1) of example 1 of the present invention;
244mg of the graphite flake-phase carbon nitride prepared above was taken, and 100mL of distilled water was added and dispersed to give a graphite flake-phase carbon nitride suspension of 2.44 mg/mL.
(2) Firstly adding a composite nitrate consisting of barium nitrate and nickel nitrate with the mass ratio of 1:1.59 into the flaky graphite phase carbon nitride suspension in the step (1), wherein the mass ratio of the composite nitrate to the flaky graphite phase carbon nitride is 1: 1.31; ultrasonically dispersing for 60min, and then adding citric acid and alkylphenol ethoxylates, wherein the mass ratio of the citric acid to the composite nitrate is 2:1, and the mass of the alkylphenol ethoxylates is 2.5 percent of the mass of the composite nitrate; after citric acid and alkylphenol ethoxylates are completely dissolved, ammonia water is dripped into the solution to adjust the pH value to 11, and a complex reaction is carried out to obtain the perovskite nanocrystal/flaky graphite phase carbon nitride precursor solution (wherein the actual mass of each raw material is 130.6mg of barium nitrate, 145.5mg of nickel nitrate, 552.2mg of citric acid, and 6.9mg of alkylphenol ethoxylates (OP-10)).
(3) And (3) ageing the perovskite nanocrystalline/flaky graphite phase carbon nitride precursor liquid obtained in the step (2) in a constant-temperature water bath at 70 ℃ for 8h, and then drying the precursor liquid in a drying oven at 80 ℃ to obtain the perovskite nanocrystalline/flaky graphite phase carbon nitride precursor xerogel.
(4) Heating the perovskite nanocrystalline/flaky graphite phase carbon nitride precursor xerogel obtained in the step (3) at 10 ℃/min in the air atmosphere, heating to 500 ℃ for first calcination for 2h, and cooling to room temperature along with the furnace; and then heating the mixture in a vacuum atmosphere at a temperature of 10 ℃/min, heating the mixture to 650 ℃ for second calcination treatment, wherein the calcination time is 2 hours, and cooling the mixture to room temperature along with the furnace to obtain the perovskite nanocrystal/flake graphite phase carbon nitride composite material.
The perovskite nanocrystal/flake graphite phase carbon nitride composite material provided by the embodiment comprises flake graphite phase carbon nitride and BaNiO distributed on the surface of the flake graphite phase carbon nitride3Perovskite nanocrystalline composition, and BaNiO3Perovskite nanocrystals in BaNiO3The mass percentage of the perovskite nanocrystalline/flaky graphite phase carbon nitride composite material is 33%.
As can be seen from fig. 5, the barium nickelate particles prepared according to the technical scheme of example 3 have an average grain size of about 200nm and are distributed uniformly on the graphite-phase carbon nitride flake.
Testing the photocatalytic hydrogen production performance:
the photocatalytic hydrogen production experiment is carried out in a quartz glass photoreactor, the mouth of the reactor is connected with a vacuum circulation system, a xenon lamp provided with a 420nm optical filter is used as a light source, and the distance between the window of the reactor and the light source is 10 cm; the perovskite nanocrystalline/flake graphite phase carbon nitride composite material prepared in the embodiment 1-3 of the invention is used as a catalyst for photocatalytic hydrogen production, and compared with the photocatalytic performance of single flake graphite phase carbon nitride and pure lanthanum ferrite perovskite, the method comprises the following specific steps:
respectively taking 50mg of each of the three perovskite nanocrystalline/flaky graphite phase carbon nitride composite materials prepared in the embodiments 1-3, respectively adding 10mL of triethanolamine, 4mL of chloroplatinic acid aqueous solution with the mass concentration of 1% and 90mL of distilled water into each of the three composite materials, respectively performing ultrasonic treatment for 30min, adding the three composite materials into a reactor, and vacuumizing a hydrogen production system for 10min by using a vacuum pump to remove air; then, starting a light source, and carrying out photocatalytic hydrogen production under the condition of magnetic stirring; in the process of photocatalytic hydrogen production, the temperature of the system is kept at 4 ℃ by circulating cooling water, the content of generated hydrogen is recorded every 60min, and the content of the obtained hydrogen is measured by a gas chromatograph (GC-7900, carrier gas is N)2) And online sampling and analyzing.
The specific steps and parameters of the photocatalytic hydrogen production of single flake graphite phase carbon nitride and pure lanthanum ferrite perovskite are the same as those of the hydrogen production processes of the above embodiments 1 to 3.
FIG. 6 is a graph showing hydrogen production rate curves of three perovskite nanocrystalline/flake graphite phase carbon nitride composite materials prepared in examples 1 to 3 according to the present invention, in which CNNS is a carbon nitride nanosheet, LFO is a pure lanthanum ferrite LaFeO3SMO/CNNS is SrMnO of example 13The perovskite nanocrystal/graphite flake phase carbon nitride composite, LFO/CNNS, is the LaFeO of example 23Perovskite nanocrystalline/graphite flake phase carbon nitride composite, BNO/CNNS being BaNiO of example 33Perovskite nanocrystal/graphite flake phase carbon nitride composites). As can be seen from the hydrogen production rate of hydrogen production by photocatalytic water splitting in FIG. 6, the photocatalytic hydrogen production rates of the three perovskite nanocrystal/flake graphite phase carbon nitride composite materials prepared in the embodiments 1 to 3 of the present invention can reach 1329.54 μmol h, respectively-1g-1、1258.06μmolh-1g-1、1189.49μmolh-1g-1While the hydrogen production rates of the single flake graphite phase carbon nitride and the pure lanthanum ferrite perovskite are 476.04 mu molh respectively-1g-1、375.6μmolh-1g-1. Thus, three perovskite nanocrystalline/flake graphite phase nitrogenations prepared in examples 1 to 3 of the present inventionThe hydrogen production capacity of the carbon composite material is far better than that of single flake graphite phase carbon nitride and pure lanthanum ferrite perovskite, and the photocatalytic hydrogen production capacity of the composite material in the embodiment 1 is optimal.
The foregoing is only a preferred embodiment of the present invention, and it should be noted that, for those skilled in the art, various modifications and decorations can be made without departing from the principle of the present invention, and these modifications and decorations should also be regarded as the protection scope of the present invention.
Claims (10)
1. A perovskite nanocrystalline/flake graphite phase carbon nitride composite material comprises flake graphite phase carbon nitride and perovskite nanocrystalline distributed on the surface of the flake graphite phase carbon nitride; the mass content of the perovskite nanocrystalline in the perovskite nanocrystalline/flake graphite phase carbon nitride composite material is 11% -33%; the average grain size of the perovskite nanocrystal is 70-200 nm.
2. The perovskite nanocrystal/flake graphite phase carbon nitride composite of claim 1, wherein the perovskite nanocrystal comprises one of a lanthanum manganate nanocrystal, a strontium manganate nanocrystal, a barium manganate nanocrystal, a lanthanum ferrite nanocrystal, a strontium ferrite nanocrystal, a barium ferrite nanocrystal, a lanthanum nickelate nanocrystal, a strontium nickelate nanocrystal, and a barium nickelate nanocrystal.
3. A process for the preparation of a perovskite nanocrystalline/graphite flake phase carbon nitride composite material according to claim 1 or 2, characterized by comprising the steps of:
(1) providing a flaky graphite phase carbon nitride suspension;
(2) sequentially adding composite nitrate, citric acid and alkylphenol ethoxylates into the flaky graphite-phase carbon nitride suspension in the step (1) for a complexing reaction to obtain a perovskite nanocrystalline/flaky graphite-phase carbon nitride precursor solution;
(3) sequentially aging and drying the perovskite nanocrystalline/flaky graphite phase carbon nitride precursor liquid obtained in the step (2) to obtain perovskite nanocrystalline/flaky graphite phase carbon nitride precursor xerogel;
(4) and (4) sequentially carrying out primary calcination and secondary calcination treatment on the perovskite nanocrystalline/flaky graphite phase carbon nitride precursor xerogel obtained in the step (3) to obtain the perovskite nanocrystalline/flaky graphite phase carbon nitride composite material.
4. The method of preparing a perovskite nanocrystal/graphite flake phase carbon nitride composite material according to claim 3, wherein the complex nitrate in the step (2) comprises a nitrate of group A and a nitrate of group B; the nitrate in the group A is lanthanum nitrate, strontium nitrate or barium nitrate; the nitrate in the group B is manganese nitrate, ferric nitrate or nickel nitrate.
5. The method for producing a perovskite nanocrystal/graphite flake phase carbon nitride composite material according to claim 3, wherein the mass ratio of the complex nitrate to the graphite flake phase carbon nitride in the step (2) is 1: (0.28-3.30).
6. The method for preparing a perovskite nanocrystal/graphite flake phase carbon nitride composite material according to claim 3, wherein the mass ratio of citric acid to the composite nitrate in the step (2) is (1.5-2.2): 1.
7. the method for preparing a perovskite nanocrystal/graphite flake phase carbon nitride composite material according to claim 3, wherein the mass of the alkylphenol ethoxylate in the step (2) is 2-2.8% of the mass of the composite nitrate.
8. The method for preparing the perovskite nanocrystal/graphite flake phase carbon nitride composite material according to claim 2, wherein the aging temperature in the step (3) is 50 to 70 ℃, and the aging time is 8 to 24 hours.
9. The method for preparing a perovskite nanocrystal/graphite flake phase carbon nitride composite material according to claim 3, wherein the temperature of the first calcination in the step (4) is 400 to 500 ℃, and the time of the first calcination is 2 to 4 hours.
10. The method for preparing a perovskite nanocrystal/graphite flake phase carbon nitride composite material according to claim 3, wherein the temperature of the second calcination in the step (4) is 550 to 650 ℃, and the time of the second calcination is 2 to 4 hours.
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| CN115805095B (en) * | 2022-12-12 | 2024-02-06 | 东南大学 | High specific surface area porous composite photocatalyst, preparation method, integrated treatment system and treatment method |
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