Bimetallic perovskite loaded graphene-like carbon nitride visible-light photocatalyst and its preparation method

Abstract

Disclosed is a method for preparing a bimetallic perovskite loaded grapheme-like carbon nitride photocatalyst, comprising: 11) dissolving SbCl.sub.3 and AgCl in HCl solution under heating and constant stirring; then adding CsCl in the heated solution to form sediment on the bottom of the beaker; collecting the sediment and wash it with ethanol, and finally drying in an oven to obtain Cs.sub.2AgSbCl.sub.6 powder; 12) adding melamine into an aluminum oxide crucible and placing it into a muffle furnace for calcination and finally cooling to room temperature naturally to obtain g-C.sub.3N.sub.4 samples; 13) adding the Cs.sub.2AgSbCl.sub.6 bimetallic perovskite and the g-C.sub.3N.sub.4 into a solvent, and stirring after subjecting to ultrasound, and drying after centrifuging to obtain the photocatalyst. Provided is a new idea for the combination of bimetallic halide perovskite and photocatalytic material, and the preparation method has mild conditions, simple operation, and is favorable for large-scale production.

Claims

1. A method for preparing a bimetallic perovskite loaded graphene-like carbon nitride photocatalyst, comprising the following steps of: (11) dissolving SbCl.sub.3 and AgCl solid reagents in a beaker containing HCl solution under constant stirring and heating; then, adding CsCl in the heated solution to form sediment on the bottom of the beaker; collecting the sediment and washing the sediment with ethanol and finally drying in an oven; after cooling the oven to room temperature, taking out to obtain Cs.sub.2AgSbCl.sub.6 powder; (12) adding melamine to an aluminum oxide crucible and covering the aluminum oxide crucible with a lid, placing the aluminum oxide crucible in a muffle furnace for calcination in static air, and finally after cooling to room temperature naturally, collecting g-C.sub.3N.sub.4 sample; (13) adding the Cs.sub.2AgSbCl.sub.6 powder and the g-C.sub.3N.sub.4 to a solvent, stirring after subjecting to ultrasound, and directly centrifuging followed by drying to obtain the bimetallic perovskite loaded graphene-like carbon nitride photocatalyst, wherein a mass ratio of Cs.sub.2AgSbCl.sub.6 powder to g-C.sub.3N.sub.4 in step (13) is (0.0016-0.016): 0.8.

2. The method for preparing the bimetallic perovskite loaded graphene-like carbon nitride photocatalyst according to claim 1, wherein SbCl.sub.3, AgCl, HCl, CsCl in step (11) are in an amount of 1 mmol, 1 mmol, 12 ml, 2 mmol, respectively.

3. The method for preparing the bimetallic perovskite loaded graphene-like carbon nitride photocatalyst according to claim 1, wherein a temperature for heating and dissolving in step (11) is 80 C.

4. The method for preparing the bimetallic perovskite loaded graphene-like carbon nitride photocatalyst according to claim 1, wherein the sediment is collected and washed with ethanol and finally dried in an oven at 120-150 C. for 5-7 hours in step (11).

5. The method for preparing the bimetallic perovskite loaded graphene-like carbon nitride photocatalyst according to claim 1, wherein the melamine in step (12) is in an amount of 10 g.

6. The method for preparing the bimetallic perovskite loaded graphene-like carbon nitride photocatalyst according to claim 1, wherein the calcination in step (12) is performed under a calcination temperature of 450-500 C., a calcination time of 0.5-2 hours and a heating rate of 10-15 C./min.

7. The method for preparing the bimetallic perovskite loaded graphene-like carbon nitride photocatalyst according to claim 1, wherein the solvent in step (13) is one or more of ethanol and isopropanol.

8. The method for preparing the bimetallic perovskite loaded graphene-like carbon nitride photocatalyst according to claim 1, wherein the ultrasound is performed for 10-30 minutes followed by stirring for 3-5 hours in step (13).

Description

BRIEF DESCRIPTION OF DRAWINGS

(1) In order to illustrate the technical solutions in the examples of the present disclosure more clearly, the accompanying drawings required in the description of the examples will be briefly introduced below. Obviously, for those skilled in the art, without creative efforts, other drawings can also be obtained according to these accompanying drawings.

(2) FIG. 1 is a flow chart of a method of preparing Cs.sub.2AgSbCl.sub.6 bimetallic perovskite loaded graphene-like carbon nitride (g-C.sub.3N.sub.4) visible-light photocatalyst provided in Examples of the present disclosure;

(3) FIG. 2 is XRD patterns (XRD is an abbreviation of X-ray diffraction) of Cs.sub.2AgSbCl.sub.6 bimetallic perovskite loaded graphene-like nitride oxide (g-C.sub.3N.sub.4) visible-light photocatalysts with four different mass ratios of Cs.sub.2AgSbCl.sub.6 (0.2%, 0.5%, 1%, 2%) prepared in Examples 1, 2, 3 and 4 of the present disclosure, and pure phase Cs.sub.2AgSbCl.sub.6, and g-C.sub.3N.sub.4;

(4) FIGS. 3 and 4 are XPS patterns (XPS is an abbreviation of X-ray photoelectron spectroscopy) of Cs.sub.2AgSbCl.sub.6 bimetallic perovskite loaded graphene-like carbon nitride (g-C.sub.3N.sub.4) visible-light photocatalyst prepared in Example 2 of the present disclosure with 0.5% loading and the pure phase g-C.sub.3N.sub.4, respectively;

(5) FIGS. 5 and 6 are SEM images (SEM is an abbreviation of Scanning Electron Microscope) of the pure phase g-C.sub.3N.sub.4 prepared in the Examples of the present disclosure and Cs.sub.2AgSbCl.sub.6 bimetallic perovskite loaded graphene-like carbon nitride (g-C.sub.3N.sub.4) visible-light photocatalyst with 0.5% loading prepared in Example 2, respectively;

(6) FIGS. 7 and 8 are TEM images (TEM is an abbreviation of Transmission Electron Microscope) of the pure-phase g-C.sub.3N.sub.4 prepared in Examples of the present disclosure and Cs.sub.2AgSbCl.sub.6 bimetallic perovskite loaded graphene-like carbon nitride (g-C.sub.3N.sub.4) visible-light photocatalyst with 0.5% loading prepared in Example 2, respectively;

(7) FIG. 9 is UV-Vis DRS patterns (UV-Vis DRS is UV-Visible Diffuse-reflection Spectra) of Cs.sub.2AgSbCl.sub.6 bimetallic perovskite loaded graphene-like carbon nitride (g-C.sub.3N.sub.4) visible-light photocatalyst with 0.5% loading prepared in Example 2 of the present disclosure and the pure-phase g-C.sub.3N.sub.4 prepared in Examples, respectively, and FIG. 10 is a band gap map of the two materials;

(8) FIG. 11 is an image of comparison of the degradation efficiency for NO purification under visible-light condition between Cs.sub.2AgSbCl.sub.6 bimetallic perovskite loaded graphene-like nitride oxides (g-C.sub.3N.sub.4) visible-light photocatalysts with four different mass ratios of Cs.sub.2AgSbCl.sub.6 (0.2%, 0.5%, 1%, 2%) prepared in Examples 1, 2, 3 and 4 of the present disclosure and the pure phase Cs.sub.2AgSbCl.sub.6 and g-C.sub.3N.sub.4;

(9) FIG. 12 is ESR (.Math.O2.sup.) patterns (ESR is an abbreviation of Electron Spin Resonance) of Cs.sub.2AgSbCl.sub.6 bimetallic perovskite loaded graphene-like nitride oxides (g-C.sub.3N.sub.4) visible-light photocatalyst prepared in Example 2 of the present disclosure with a mass ratio of 0.5% and the pure phase Cs.sub.2AgSbCl.sub.6 and g-C.sub.3N.sub.4;

(10) FIG. 13 is ESR (.Math.OH) patterns of the Cs.sub.2AgSbCl.sub.6 bimetallic perovskite loaded graphene-like carbon nitride (g-C.sub.3N.sub.4) visible-light photocatalyst with a mass ratio of 0.5% prepared in Example 2 of the present disclosure and the pure phase Cs.sub.2AgSbCl.sub.6 and g-C.sub.3N.sub.4;

(11) FIG. 14 is a time-resolved fluoroimmunoassay image of 0.5% Cs.sub.2AgSbCl.sub.6 bimetallic perovskite loaded graphene-like carbon nitride (g-C.sub.3N.sub.4) visible-light photocatalyst prepared in Example 2 of the present disclosure and the pure-phase Cs.sub.2AgSbCl.sub.6 and g-C.sub.3N.sub.4.

DETAILED DESCRIPTION

(12) Referring to FIG. 1, the Examples 1, 2, 3 and 4 of the present disclosure provide methods of preparing Cs.sub.2AgSbCl.sub.6 bimetallic perovskite loaded graphene-like carbon nitride (g-C.sub.3N.sub.4) visible-light photocatalysts, comprising the following steps of: 11) dissolving 1 mmol of SbCl.sub.3 and 1 mmol of AgCl solid reagents in a beaker containing 12 ml of HCl solution, and heating it to 80 C. with constant stirring to dissolve; then, adding 2 mmol of CsCl into the heated solution to form sediment on the bottom of the beaker in a short time; collecting the sediment and washing it three times with ethanol, and finally drying it in an oven at 120-150 C. for 5-7 h; after cooling the oven to room temperature, taking out to obtain Cs.sub.2AgSbCl.sub.6 powder; 12) adding 10 g of melamine into an aluminum oxide crucible, and after covering with a lid, placing it in a muffle furnace for calcination in static air under a calcination temperature of 450-500 C., a calcination time of 0.5-2 h and a heating rate of 1015 C./min, and finally cooling it to room temperature naturally, and collecting the g-C.sub.3N.sub.4 samples; 13) adding Cs.sub.2AgSbCl.sub.6 bimetallic perovskite and g-C.sub.3N.sub.4 into a solvent, and after subjecting to ultrasound for 1030 min, stirring for 35 h, and directly centrifuging and drying at 60 C. to obtain the Cs.sub.2AgSbCl.sub.6 bimetallic perovskite loaded graphene-like graphene carbon nitride (g-C.sub.3N.sub.4) visible-light photocatalyst.

(13) As can be seen from experimental analysis, for the Cs.sub.2AgSbCl.sub.6 bimetallic perovskite and g-C.sub.3N.sub.4 visible-light photocatalyst obtained by the preparation methods provided by the present disclosure, the heterojunctions accelerate the migration of carriers, and electrons pass through the g-C.sub.3N.sub.4 and transfer onto the Cs.sub.2AgSbCl.sub.6 bimetallic perovskite, thereby inhibiting the electron-hole recombination efficiency and improving the charge transfer performance, promoting the generation of free radicals, and thus improving its visible-light photocatalytic activity.

(14) By characterizing the Cs.sub.2AgSbCl.sub.6 bimetallic perovskite loaded graphene-like carbon nitride (g-C.sub.3N.sub.4) visible-light photocatalysts prepared in Examples 1, 2, 3 and 4 of the present disclosure, it can be seen that the Cs.sub.2AgSbCl.sub.6 bimetallic perovskite loaded graphene-like carbon nitrode (g-C.sub.3N.sub.4) visible-light photocatalysts exhibit the following characteristics: (1) XRD analysis was performed on Cs.sub.2AgSbCl.sub.6 bimetallic perovskite loaded graphene-like carbon nitride (g-C.sub.3N.sub.4) visible-light photocatalysts and the pure phase Cs.sub.2AgSbCl.sub.6 and g-C.sub.3N.sub.4 (as shown in FIG. 2) and confirmed that the Cs.sub.2AgSbCl.sub.6 bimetallic perovskite loaded graphene-like carbon nitride (g-C.sub.3N.sub.4) visible-light photocatalysts and the pure phase Cs.sub.2AgSbCl.sub.6 and g-C.sub.3N.sub.4 had a complete and stable g-C.sub.3N.sub.4 crystal structure, and that the characteristic peaks of the Cs.sub.2AgSbCl.sub.6 and the g-C.sub.3N.sub.4 appeared in the Cs.sub.2AgSbCl.sub.6/g-C.sub.3N.sub.4 heterojunction material with the increasing loading of the Cs.sub.2AgSbCl.sub.6. (2) XPS analysis was performed on the Cs.sub.2AgSbCl.sub.6 bimetallic perovskite loaded graphene-like carbon nitride (g-C.sub.3N.sub.4) visible light catalyst and the pure phase g-C.sub.3N.sub.4 (as shown in FIGS. 3 and 4), and confirmed that the Cs.sub.2AgSbCl.sub.6 loaded composite material of the Cs.sub.2AgSbCl.sub.6 bimetallic perovskite loaded graphene-like carbon nitride (g-C.sub.3N.sub.4) visible-light photocatalysts prepared in Example 1, 2, 3 and 4 of the present disclosure had the same elements as the pure phase g-C.sub.3N.sub.4 and no other impurity elements; SEM analysis and TEM analysis was performed on the pure phase g-C.sub.3N.sub.4 and Cs.sub.2AgSbCl.sub.6 bimetallic perovskite loaded graphene-like carbon nitride (g-C.sub.3N.sub.4) visible-light photocatalysts (as shown in FIGS. 5, 6, 7 and 8), and confirmed the successful preparation of the materials that exhibited a loose and porous structure. (3) UV-VisDRS analysis was performed on the Cs.sub.2AgSbCl.sub.6 bimetallic perovskite loaded graphene-like carbon nitride (g-C.sub.3N.sub.4) visible-light photocatalyst with a mass percentage of 0.5% prepared in Example 2 and the pure phase g-C.sub.3N.sub.4 (as shown in FIG. 9) to test its photoresponse range, and confirmed that the introduction of Cs.sub.2AgSbCl.sub.6 can enhance the absorption of light from the ultraviolet-visible-infrared region by the g-C.sub.3N.sub.4. Meanwhile, the band gap of 0.5% Cs.sub.2AgSbCl.sub.6 bimetallic perovskite loaded graphene-like carbon nitride (g-C.sub.3N.sub.4) visible-light photocatalyst (2.6 eV) was narrower than that of the pure phase g-C.sub.3N.sub.4 (2.75 eV), as shown in the band gap map calculated from UV-visDRS (FIG. 10), which indicated that the light absorption and electron-hole pair separation of the pure phase g-C.sub.3N.sub.4 could be improved to a certain extent by the loading of Cs.sub.2AgSbCl.sub.6.

(15) The photocatalytic performance of the Cs.sub.2AgSbCl.sub.6 bimetallic perovskite loaded graphene-like carbon nitride (g-C.sub.3N.sub.4) visible-light photocatalysts prepared by Examples 1, 2, 3 and 4 of the present disclosure was tested by degrading NO. The test process was as follows: (1) 0.2 g of the Cs.sub.2AgSbCl.sub.6 bimetallic perovskite loaded graphene-like carbon nitride (g-C.sub.3N.sub.4) visible-light photocatalyst prepared in either of the examples was placed on a glass disc; (2) Four small fans were installed around a reactor; (3) Under dark conditions, when the concentration of NO reached equilibrium, the Cs.sub.2AgSbCl.sub.6 bimetallic perovskite loaded graphene-like carbon nitride (g-C.sub.3N.sub.4) visible-light photocatalyst was irradiated with a 150 W halogen tungsten lamp for 30 min.

(16) The conditions of the above catalytic performance test process included: a relative humidity of 60%; an oxygen content of 21%; a NO gas flow rate of 2.24 L/min; an initial NO concentration of 550 g/kg; filtering out UV light with a 420 nm cut-off filter before irradiating with the halogen tungsten lamp.

(17) The Cs.sub.2AgSbCl.sub.6 bimetallic perovskite loaded graphene-like carbon nitride (g-C.sub.3N.sub.4) visible-light photocatalysts provided in examples of the present disclosure have the following degradation effects on NO degradation: (1) The Cs.sub.2AgSbCl.sub.6 bimetallic perovskite loaded graphene-like carbon nitride (g-C.sub.3N.sub.4) visible-light photocatalyst has a NO degradation efficiency of 30%50% (as shown in FIG. 11), which is higher than the NO degradation efficiency of the pure phase g-C.sub.3N.sub.4 of 21%; the calculation formula of the degradation efficiency is (%)=(1C/C.sub.0)100%, where C.sub.0 is an initial NO concentration and C is an instantaneous concentration of NO. (2) Superoxide ion (.Math.O2.sup.) is the most important degradation radical for the degradation of NO under visible-light by the Cs.sub.2AgSbCl.sub.6 bimetallic perovskite loaded graphene-like carbon nitride (g-C.sub.3N.sub.4) visible-light photocatalysts (as shown in FIG. 12), and hydroxyl ion (.Math.OH) is the secondary degradation radical (as shown in FIG. 13). (3) The time-resolved flurescence test was performed on the Cs.sub.2AgSbCl.sub.6 bimetallic perovskite loaded graphene-like carbon nitride (g-C.sub.3N.sub.4) visible-light photocatalyst and the pure phase Cs.sub.2AgSbCl.sub.6 and g-C.sub.3N.sub.4, and confirmed that the flurescence lifetime of the Cs.sub.2AgSbCl.sub.6 bimetallic perovskite loaded graphene-like carbon nitride (g-C.sub.3N.sub.4) photocatalyst was increased, and the separation effect of photogenerated electrons and holes was enhanced (as shown in FIG. 14).

(18) Several specific examples are listed for the preparation method disclosed in the present disclosure, and the described examples are only a part of the embodiments of the present disclosure. Based on the examples of the present disclosure, all embodiments obtainable by those skilled in the art without creative labor fall into the scope of protection of the present disclosure.

Example 1

(19) A method for preparing a Cs.sub.2AgSbCl.sub.6 bimetallic perovskite loaded graphene-like carbon nitride (g-C.sub.3N.sub.4) visible-light photocatalyst included the following steps:

(20) 1 mmol of SbCl.sub.3 and 1 mmol of AgCl solid reagents were weighed and dissolved in a beaker containing 12 ml of HCl solution and heated to 80 C. with constant stirring to dissolve. 2 mmol of CsCl was then added into the heated solution. Sediment was soon formed at the bottom of the beaker. The sediment was collected and washed three times with ethanol and finally dried in an oven at 150 C. for 7 h. After cooling the oven to room temperature, Cs.sub.2AgSbCl.sub.6 powder was taken out and obtained; 10 g of melamine was weighed and added to an aluminum oxide crucible and was placed in a muffle furnace for calcination after covering with a lid. The calcination was performed in static air, and the calcination temperature was 550 C., and the calcination time was 2 h, and the heating rate was 10 C./min. Finally, after cooling to room temperature naturally, the g-C.sub.3N.sub.4 sample was collected. 0.0016 g of the Cs.sub.2AgSbCl.sub.6 bimetallic perovskite and 0.8 g of the g-C.sub.3N.sub.4 were added to 200 ml of ethanol, subjected to ultrasound for 30 min, stirred for 4 h, directly centrifuged and dried at 60 C. to obtain 0.2% Cs.sub.2AgSbCl.sub.6 bimetallic perovskite loaded graphene-like carbon nitride (g-C.sub.3N.sub.4) visible-light photocatalyst.

(21) The mass ratio of Cs.sub.2AgSbCl.sub.6 bimetallic perovskite loaded graphene-like carbon nitride (g-C.sub.3N.sub.4) visible-light photocatalyst prepared in Example 1 of the present disclosure was 0.2%. The 0.2% Cs.sub.2AgSbCl.sub.6 bimetallic perovskite loaded graphene-like carbon nitride (g-C.sub.3N.sub.4) visible-light photocatalyst was used for NO degradation. The specific process was as follows: under the conditions of a relative humidity of 60%, an oxygen content of 21%, a flow rate of NO gas flow of 2.24 L/min and an initial concentration of NO of 550 m/kg, 0.2 g of the 0.2% Cs.sub.2AgSbCl.sub.6 bimetallic perovskite loaded graphene-like carbon nitride (g-C.sub.3N.sub.4) visible-light photocatalyst prepared in Example 1 was placed on a glass disc; four small fans were installed around the reactor; under dark conditions, a 420 nm cut-off filter was used to filter out UV light, and when the NO concentration reached equilibrium, a 150 W halogen tungsten lamp was used to irradiate the Cs.sub.2AgSbCl.sub.6 Bimetallic perovskite loaded graphene-like carbon nitride (g-C.sub.3N.sub.4) visible-light photocatalyst for 30 min; the lamp was turned off finally. After calculation, the Cs.sub.2AgSbCl.sub.6 bimetallic perovskite loaded graphene-like carbon nitride (g-C.sub.3N.sub.4) visible-light photocatalyst prepared in Example 1 of the present disclosure had a NO degradation efficiency of 31%. Compared to two substrates, the Cs.sub.2AgSbCl.sub.6 bimetallic perovskite loaded graphene-like carbon nitride (g-C.sub.3N.sub.4) visible-light photocatalyst has the improved NO degradation efficiency.

Example 2

(22) A method for preparing a Cs.sub.2AgSbCl.sub.6 bimetallic perovskite loaded graphene-like carbon nitride (g-C.sub.3N.sub.4) visible-light photocatalyst included the following steps:

(23) 1 mmol of SbCl.sub.3 and 1 mmol of AgCl solid reagents were weighed and dissolved in a beaker containing 12 ml of HCl solution and heated to 80 C. with constant stirring to dissolve. 2 mmol of CsCl was then added into the heated solution. Sediment was soon formed at the bottom of the beaker. The sediment was collected and washed three times with ethanol and finally dried in an oven at 150 C. for 7 h. After cooling the oven to room temperature, Cs.sub.2AgSbCl.sub.6 powder was taken out and obtained; 10 g of melamine was weighed and added to an aluminum oxide crucible and was placed in a muffle furnace for calcination after covering with a lid. The calcination was performed in static air, and the calcination temperature was 550 C., and the calcination time was 2 h, and the heating rate was 10 C./min. Finally, after cooling to room temperature naturally, the g-C.sub.3N.sub.4 sample was collected. 0.004 g of the Cs.sub.2AgSbCl.sub.6 bimetallic perovskite and 0.8 g of the g-C.sub.3N.sub.4 were added to 200 ml of ethanol, subjected to ultrasound for 30 min, stirred for 4 h, directly centrifuged and dried at 60 C. to obtain 0.5% Cs.sub.2AgSbCl.sub.6 bimetallic perovskite loaded graphene-like carbon nitride (g-C.sub.3N.sub.4) visible-light photocatalyst.

(24) The mass ratio of the Cs.sub.2AgSbCl.sub.6 bimetallic perovskite loaded graphene-like carbon nitride (g-C.sub.3N.sub.4) visible-light photocatalyst prepared in Example 2 of the present disclosure was 0.5%. The 0.5% Cs.sub.2AgSbCl.sub.6 bimetallic perovskite loaded graphene-like carbon nitride (g-C.sub.3N.sub.4) visible-light photocatalyst was used for NO degradation, and the test process was the same as that of Example 1. After calculation, the Cs.sub.2AgSbCl.sub.6 bimetallic perovskite loaded graphene-like carbon nitride (g-C.sub.3N.sub.4) visible-light photocatalyst prepared in Example 2 of the present disclosure had a NO degradation efficiency of 43%. Compared to two substrates, the Cs.sub.2AgSbCl.sub.6 bimetallic perovskite loaded graphene-like carbon nitride (g-C.sub.3N.sub.4) visible-light photocatalyst had the improved NO degradation efficiency.

Example 3

(25) A method for preparing a Cs.sub.2AgSbCl.sub.6 bimetallic perovskite loaded graphene-like carbon nitride (g-C.sub.3N.sub.4) visible-light photocatalyst included the following steps:

(26) 1 mmol of SbCl.sub.3 and 1 mmol of AgCl solid reagents were weighed and dissolved in a beaker containing 12 ml of HCl solution and heated to 80 C. with constant stirring to dissolve. 2 mmol of CsCl was then added into the heated solution. Sediment was soon formed at the bottom of the beaker. The sediment was collected and washed three times with ethanol and finally dried in the oven at 150 C. for 7 h. After cooling the oven to room temperature, Cs.sub.2AgSbCl.sub.6 powder was taken out and obtained; 10 g of melamine was weighed and added to an aluminum oxide crucible and was placed in a muffle furnace for calcination after covering with a lid. The calcination condition was performed in static air, and the calcination temperature was 550 C., and the calcination time was 2 h, and the heating rate was 10 C./min. Finally, after cooling to room temperature naturally, the g-C.sub.3N.sub.4 sample was collected. 0.008 g of the Cs.sub.2AgSbCl.sub.6 bimetallic perovskite and 0.8 g of the g-C.sub.3N.sub.4 were added to 200 ml of ethanol, and subjected to ultrasound for 30 min, stirred for 4 h, directly centrifuged and dried at 60 C. to obtain 1% Cs.sub.2AgSbCl.sub.6 bimetallic perovskite loaded graphene-like carbon nitride (g-C.sub.3N.sub.4) visible-light photocatalyst.

(27) The mass ratio of the Cs.sub.2AgSbCl.sub.6 bimetallic perovskite loaded graphene-like carbon nitride (g-C.sub.3N.sub.4) visible-light photocatalyst prepared in Example 3 of the present disclosure was 1%. The 1% Cs.sub.2AgSbCl.sub.6 bimetallic perovskite loaded graphene-like carbon nitride (g-C.sub.3N.sub.4) visible-light photocatalyst was used for NO degradation, and the test process was the same that of Example 1. After calculation, the Cs.sub.2AgSbCl.sub.6 bimetallic perovskite loaded graphene-like carbon nitride (g-C.sub.3N.sub.4) visible-light photocatalyst prepared in Example 3 of the present disclosure had a NO degradation efficiency of 35%. Compared to two substrates, the Cs.sub.2AgSbCl.sub.6 bimetallic perovskite loaded graphene-like carbon nitride (g-C.sub.3N.sub.4) visible-light photocatalyst had the improved NO degradation efficiency.

Example 4

(28) A method for preparing a Cs.sub.2AgSbCl.sub.6 bimetallic perovskite loaded graphene-like carbon nitride (g-C.sub.3N.sub.4) visible-light photocatalyst included the following steps:

(29) 1 mmol of SbCl.sub.3 and 1 mmol of AgCl solid reagents were weighed and dissolved in a beaker containing 12 ml of HCl solution and heated to 80 C. with constant stirring to dissolve. 2 mmol of CsCl was then added into the heated solution. Sediment was soon formed at the bottom of the beaker. The sediment was collected and washed three times with ethanol and finally dried in the oven at 150 C. for 7 h. After cooling the oven to room temperature, Cs.sub.2AgSbCl.sub.6 powder was taken out and obtained; 10 g of melamine was weighed and added to an aluminum oxide crucible and was placed in a muffle furnace for calcination after covering with a lid. The calcination condition was performed in static air, and the calcination temperature was 550 C., and the calcination time was 2 h, and the heating rate was 10 C./min. Finally, after cooling to room temperature naturally, the g-C.sub.3N.sub.4 sample was collected. 0.016 g of the Cs.sub.2AgSbCl.sub.6 bimetallic perovskite and 0.8 g of the g-C.sub.3N.sub.4 were added to 200 ml of ethanol, and after subjected to ultrasound for 30 min, stirred for 4 h, directly centrifuged and dried at 60 C. to obtain 2% Cs.sub.2AgSbCl.sub.6 bimetallic perovskite loaded graphene-like carbon nitride (g-C.sub.3N.sub.4) visible-light photocatalyst.

(30) The 2% Cs.sub.2AgSbCl.sub.6 bimetallic perovskite loaded graphene-like carbon nitride (g-C.sub.3N.sub.4) visible-light photocatalyst prepared in Example 4 of the present disclosure was used for NO degradation, and the test process was the same that of Example 1. After calculation, the Cs.sub.2AgSbCl.sub.6 bimetallic perovskite loaded graphene-like carbon nitride (g-C.sub.3N.sub.4) visible-light photocatalyst prepared in Example 4 of the present disclosure had a NO degradation efficiency of 37%. Compared to two substrates, the Cs.sub.2AgSbCl.sub.6 bimetallic perovskite loaded graphene-like carbon nitride (g-C.sub.3N.sub.4) visible-light photocatalyst had the improved NO degradation efficiency.

(31) From the above examples, it can be seen from comparison between the degradation of NO by the Cs.sub.2AgSbCl.sub.6 bimetallic perovskite loaded graphene-like carbon nitride (g-C.sub.3N.sub.4) visible-light photocatalyst and the degradation of NO by pure phase Cs.sub.2AgSbCl.sub.6 and g-C.sub.3N.sub.4, the degradation efficiency of the Cs.sub.2AgSbCl.sub.6 bimetallic perovskite-supported graphene-like carbon nitride (g-C.sub.3N.sub.4) visible photocatalyst was significantly improved. Moreover, there are few research reports on the use of bimetallic halide perovskite materials in the field of photocatalysis, which is worth further exploration and application.

(32) It should be noted that the catalytic mechanism of the Cs.sub.2AgSbCl.sub.6 bimetallic perovskite loaded graphene-like carbon nitride (g-C.sub.3N.sub.4) visible-light catalysts provided in the examples of the present disclosure for sulfides, volatile organic compounds, non-NO nitrogen oxides and other air pollutants was the same as the catalytic mechanism for NO, and therefore, the degradation test of NO in the examples of the present invention are representative.

(33) While the present disclosure has been described with specific examples, for those skilled in the art, any variants and modifications made within the spirit and principle of the present disclosure defined by claims should be included in the protection scope of the present disclosure.