CN111871430B - Preparation method and application of sulfur-indium-zinc/calcium-potassium niobate two-dimensional heterojunction composite photocatalytic material - Google Patents

Abstract

The invention belongs to the field of inorganic functional materials and their preparation, specifically the preparation of a sulfur indium zinc/calcium potassium niobate two-dimensional nanosheet heterojunction composite photocatalytic material (ZnIn ₂ S ₄ /KCa ₂ Nb ₃ O ₁₀ ) Methods and uses. ZnIn ₂ S ₄ /KCa ₂ Nb ₃ O ₁₀ heterojunction composite photocatalysts with tight two-dimensional-two-dimensional interfaces were prepared by low-temperature hydrothermal method. The developed material exhibits excellent visible-light photocatalytic reduction of CO ₂ activity, the optimal ratio product is ZnIn ₂ S ₄ with a mass fraction of 20%, and the activity reaches 4.69 μmol g ^‑1 h ^‑1 , which is a pure phase ZnIn ₂ S ₄ nanometer sheet, KCa ₂ Nb ₃ O ₁₀ nanosheets are 12.31 times and 1.95 times. The method is simple and feasible, easy to repeat, and the prepared product has excellent performance, and has broad application prospects in the field of photocatalytic reduction of CO ₂ .

Description

Preparation method of a kind of sulfur indium zinc/calcium potassium niobate two-dimensional heterojunction composite photocatalytic material Law and usage

technical field

The invention relates to a preparation method and application of a sulfur indium zinc/calcium potassium niobate two-dimensional heterojunction composite photocatalytic material, belonging to the technical field of inorganic functional material preparation and photocatalysis.

technical background

With the continuous progress of industry, the problem of environmental pollution is becoming more and more prominent, especially the emission of CO ₂ gas is increasing day by day, and the greenhouse effect caused by it is constantly threatening the future development of human beings. The conversion of _CO2 into high value-added chemicals using solar-based photocatalytic technology is considered to be an effective way to solve the above problems. Therefore, the development of high-efficiency photocatalysts is of great significance. In recent years, two-dimensional (2D) nanosheet semiconductor materials have been considered as ideal materials for constructing efficient _CO2 photocatalytic reduction systems due to their large specific surface area, sufficient active sites, and short carrier migration paths. Among them, as a typical Dion-Jacobson (DJ) phase perovskite oxide, KCa ₂ Nb ₃ O ₁₀ nanosheet material has an energy band structure that matches the generation potential of carbon-based compounds, a strong ability to reduce photogenerated electrons and Excellent stability has become a research hotspot in the field of photocatalysis. However, pure-phase KCa ₂ Nb ₃ O ₁₀ nanosheets have a wide band gap (~3.4eV), can only respond to ultraviolet light, and their high recombination rate of photogenerated carriers severely limits their photocatalytic activity. Therefore, expanding the photoresponse range of KCa ₂ Nb ₃ O ₁₀ nanosheet-based photocatalysts while achieving efficient carrier separation is a key issue for realizing its high-efficiency catalysis.

In recent years, enhancing the _CO2 reduction activity of photocatalytic materials by constructing heterostructures has been widely studied. Compared with other dimensional heterojunction photocatalytic systems, 2D-2D heterojunction has a larger contact area and faster carrier separation and migration rate, so it has attracted extensive attention. Ternary chalcogenide ZnIn ₂ S ₄ nanosheets have good carrier separation ability and visible light absorption performance, but their photocatalytic stability is poor. Using it with KCa ₂ Nb ₃ O ₁₀ nanosheets to construct a 2D-2D heterojunction can not only effectively promote the light absorption ability of KCa ₂ Nb ₃ O ₁₀ , but also enhance the stability of ZnIn ₂ S ₄ , which is more conducive to promoting photogenerated current carrying sub-separation to improve the _CO2 reduction activity of photocatalysts.

However, there are still few reports on the successful preparation of 2D-2D ZnIn ₂ S ₄ /KCa ₂ Nb ₃ O ₁₀ heterojunction photocatalysts.

Contents of the invention

The purpose of the present invention is to provide a new method for synthesizing ZnIn ₂ S ₄ /KCa ₂ Nb ₃ O ₁₀ two-dimensional nano-sheet heterojunction composite photocatalytic material by a simple and easy hydrothermal method under low temperature conditions.

The present invention is realized through the following steps:

Step 1. Preparation of calcium potassium niobate nanosheets (KCa ₂ Nb ₃ O ₁₀ ):

Weigh a certain amount of dry K ₂ CO ₃ , CaCO ₃ and Nb ₂ O ₅ in a mortar, grind and mix them thoroughly, put them in a semi-closed crucible, and then transfer the crucible to an automatic temperature-controlled tube furnace Calcined. After naturally cooling to room temperature, take it out, grind it into powder with a mortar, add it into HNO ₃ solution and stir for several days to carry out protonation treatment. The white precipitate obtained by protonation was washed with deionized water and absolute ethanol to remove HNO ₃ , then centrifuged and dried to obtain white solid HCa ₂ Nb ₃ O ₁₀ .

Weigh a certain amount of HCa ₂ Nb ₃ O ₁₀ , add a certain amount of tetrabutylammonium hydroxide solution and an appropriate amount of deionized water, stir for several days, and centrifuge to obtain the upper colloidal substance. Subsequently, the colloidal substance was added dropwise into the KCl solution to obtain a white precipitate, which was washed with deionized water and absolute ethanol, centrifuged, and finally dried in a vacuum oven to obtain KCa ₂ Nb ₃ O ₁₀ nanosheets.

Step 2. Preparation of ZnIn ₂ S ₄ /KCa ₂ Nb ₃ O ₁₀ two-dimensional nanosheet heterojunction composite material:

Take KCa ₂ Nb ₃ O ₁₀ nanosheets and mix them in a certain amount of water and glycerol. After stirring evenly, add ZnCl ₂ , InCl ₃ 4H ₂ O and thioacetamide solids, and place the resulting mixed liquid in a round bottom Reaction in an oil bath in a flask, centrifugal washing and vacuum drying to obtain a ZnIn ₂ S ₄ /KCa ₂ Nb ₃ O ₁₀ two-dimensional nanosheet heterojunction composite material.

In step 1, among the reaction raw materials K ₂ CO ₃ , CaCO ₃ and Nb ₂ O ₅ , the molar ratio of K ⁺ , Ca ²⁺ and Nb ⁵⁺ is 1.1:2:3.

In step 1, the calcination temperature of the tube furnace is 1100-1400° C., and the calcination time of the tube furnace is 8-16 hours. The optimal calcination temperature is 1200°C.

In step 1, the concentration of the HNO ₃ solution is 5 mol·L ^-1 , and the protonation time is 3-5 days.

In step 1, the mass fraction of the tetrabutylammonium hydroxide solution is 10%, and the stirring time of the protonated product in the tetrabutylammonium hydroxide solution is 5-10 days; the concentration of the KCl solution is 2mol·L ^-1 .

In step 2, the mass ratio of KCa ₂ Nb ₃ O ₁₀ , ZnCl ₂ , InCl ₃ ·4H ₂ O, and thioacetamide is 100:6.41-25.62:13.78-55.12:7.11-28.42.

Further, the optimal mass ratio of KCa ₂ Nb ₃ O ₁₀ , ZnCl ₂ , InCl ₃ ·4H ₂ O, and thioacetamide is 100:12.81:27.56:14.21.

In step 2, the reaction temperature in the oil bath is 60-100° C., and the reaction time in the oil bath is 1-3 hours.

In step 2, the vacuum temperature is 60° C., and the drying time is 24 hours.

The ZnIn ₂ S ₄ /KCa ₂ Nb ₃ O ₁₀ two-dimensional heterojunction composite photocatalytic material prepared by the present invention is used to reduce CO ₂ to prepare CO.

X-ray diffractometer (XRD), transmission electron microscope (TEM) and high-resolution transmission electron microscope (HRTEM) were used to analyze the morphology and structure of the product, and the photocatalytic activity experiment was carried out by reducing carbon dioxide by xenon lamp irradiation. The retention time determines the type of reduction product, and the efficiency of reducing carbon dioxide is determined by comparing the measured peak area with the standard peak area, so as to evaluate its photocatalytic carbon dioxide reduction performance.

Beneficial effect:

(1) By constructing ZnIn ₂ S ₄ /KCa ₂ Nb ₃ O ₁₀ two-dimensional heterostructure photocatalyst, it can not only increase the light absorption ability of the material, improve the utilization rate of solar energy, but also enhance the photocatalytic stability, endow the photocatalytic material practical application value.

(2) The constructed 2D heterostructure photocatalyst with abundant heterointerfaces can effectively promote the separation of photogenerated carriers and improve the carrier utilization, thereby enhancing the photocatalytic _CO2 reduction activity.

(3) ZnIn ₂ S ₄ and KCa ₂ Nb ₃ O ₁₀ synthesized in the present invention all exhibited extremely thin nanosheet morphology, and the constructed composites had tight and abundant heterointerfaces. The heterostructure product exhibits excellent visible-light photocatalytic CO ₂ reduction activity, and the optimal ratio product (ZnIn ₂ S ₄ mass fraction is 20%) has an activity of 4.69 μmol·g ^-1 ·h ^-1 , which is a pure phase ZnIn ₂ S 12.31 times and 1.95 times that of ₄ nanosheets and KCa ₂ Nb ₃ O ₁₀ nanosheets. The method is simple and feasible, easy to repeat, and the prepared product has excellent performance, and has broad application prospects in the field of photocatalytic reduction of CO ₂ .

Description of drawings

Figure 1 is the XRD spectrum of KCa ₂ Nb ₃ O ₁₀ , ZnIn ₂ S ₄ and 20%-ZnIn ₂ S ₄ /KCa ₂ Nb ₃ O ₁₀ two-dimensional nanosheet heterojunction composite photocatalyst;

Figure 2(ac) shows the transmission electron micrographs of pure KCa ₂ Nb ₃ O ₁₀ , pure ZnIn ₂ S ₄ , ZnIn ₂ S ₄ /KCa ₂ Nb ₃ O ₁₀ two-dimensional nanosheet heterojunction composite photocatalytic materials; (d ) is a high-resolution transmission electron micrograph of ZnIn ₂ S ₄ /KCa ₂ Nb ₃ O ₁₀ two-dimensional nanosheet heterojunction composite photocatalytic material;

Figure 3(a) shows the CO yield of monomer KCa ₂ Nb ₃ O ₁₀ , ZnIn ₂ S ₄ and different mass ratios of ZnIn ₂ S ₄ /KCa ₂ Nb ₃ O ₁₀ two-dimensional nanosheet heterojunction composite photocatalytic materials Figure; (b) is the CO generation rate of monomer KCa ₂ Nb ₃ O ₁₀ , ZnIn ₂ S ₄ and different mass ratios of ZnIn ₂ S ₄ /KCa ₂ Nb ₃ O ₁₀ two-dimensional nanosheet heterojunction composite photocatalytic materials picture.

Detailed ways

The present invention will be further described below in conjunction with the accompanying drawings and specific embodiments, but the protection scope of the present invention is not limited thereto.

Example 1: Preparation and performance analysis of 20%-ZnIn ₂ S ₄ /KCa ₂ Nb ₃ O ₁₀ two-dimensional nanosheet heterojunction composite photocatalyst

_Preparation of _{KCa2Nb3O 10} nanosheets:

The preparation of KCa ₂ Nb ₃ O ₁₀ nanosheets adopts high-temperature solid-state reaction method: Weigh 0.3406g K ₂ CO ₃ , 0.8968g CaCO ₃ and 1.7865g Nb ₂ O ₅ in a mortar, grind and mix thoroughly, then place in a semi-closed The crucible was then transferred to an automatically programmed temperature-controlled tube furnace for calcination at 1200 °C for 10 h. After naturally cooling to room temperature, take it out, grind it into powder with a mortar, add 4 g into 200mL 5mol·L ^-1 HNO ₃ solution and stir for 3 days to carry out protonation treatment. The white precipitate obtained by protonation was washed three times with deionized water and absolute ethanol to remove HNO ₃ , and dried at 60°C for 12 hours after centrifugation to obtain white solid HCa ₂ Nb ₃ O ₁₀ . Disperse 0.1 g of HCa ₂ Nb ₃ O ₁₀ and 0.5 mL of 10% tetrabutylammonium hydroxide solution in 100 mL of deionized water, stir for 7 days, and centrifuge to obtain a colloidal object in the upper layer. Finally, the colloidal substance was added dropwise to 100mL 2mol L ^-1 KCl solution to obtain a white precipitate, which was washed with deionized water and absolute ethanol three times, centrifuged and dried in a vacuum oven at 60°C for 24 hours .

Preparation of 20%-ZnIn ₂ S ₄ /KCa ₂ Nb ₃ O ₁₀ two-dimensional nanosheet heterojunction composite photocatalytic material:

ZnIn ₂ S ₄ /KCa ₂ Nb ₃ O ₁₀ was prepared by a low-temperature hydrothermal method: 100 mg of KCa ₂ Nb ₃ O ₁₀ nanosheets, 16 mL of deionized water, and 4 mL of glycerol were added to a 20-mL round-bottomed flask and sonicated Stir for 30 min, then add 12.81 mg of ZnCl ₂ , 27.56 mg of InCl ₃ ·4H ₂ O and 14.21 mg of thioacetamide in sequence, stir the above mixture for 5 min, put it in an oil bath at 80°C and keep it for 2 h, wait After natural cooling, the product was centrifuged, washed three times with absolute ethanol, and finally placed in a vacuum oven at 60°C to dry the sample to obtain 20%-ZnIn ₂ S ₄ /KCa ₂ Nb ₃ O ₁₀ .

It can be seen from Figure 1 that the typical layered KCa ₂ Nb ₃ O ₁₀ diffraction peaks in the composite structure are obvious, and the newly added diffraction peaks at 20.96°, 27.48°, 30.73°, 47.30°, 52.33°, and 55.85° correspond to the hexagonal crystal phase ZnIn ₂ The (006), (102), (104), (110), (112), and (202) crystal planes of S ₄ have no other impurity peaks, which proves that the synthesized material has a composite structure and no other heterogeneous phases appear.

It can be seen from Figure 2 that the synthesized KCa ₂ Nb ₃ O ₁₀ has a rigid ultrathin nanosheet structure, while the edge of ZnIn ₂ S ₄ nanosheets is curled, which proves that the material has good flexibility. The composite product is obviously constructed from two structural nanosheets, and forms a uniform and dense heterostructure. In the high-resolution transmission electron microscope, 0.324nm and 0.411nm correspond to the (102) and (006) crystal planes of ZnIn ₂ S ₄ respectively, and 0.280nm corresponds to the (110) crystal plane of KCa ₂ Nb ₃ O ₁₀ . It is further proved that the two materials in the composite product form a heterostructure with a tight and obvious heterogeneous interface.

20%-ZnIn ₂ S ₄ /KCa ₂ Nb ₃ O ₁₀ two-dimensional nanosheet heterojunction composite material photocatalytic activity experiment:

(1) The photocatalytic _CO2 reduction experiment was carried out in a 280 mL self-made quartz reactor. Add 50mg of the sample to an appropriate amount of absolute ethanol to disperse evenly, and dry at 60°C.

(2) Add 0.084g NaHCO ₃ into the reactor tank. After bubbling under nitrogen atmosphere for 15 min, inject 0.9mL H ₂ SO ₄ (2mol L ^-1 ) to react with NaHCO ₃ to release CO ₂ and H ₂ O. The light source is a 300W xenon lamp.

(3) Detect the product with a gas chromatograph (CEAULIGHT GC-7920), inject samples into the gas chromatograph every hour for detection, and calibrate with a standard gas mixture. Each component was determined by retention time, and the concentration of each component was calculated by the external standard method of peak area. It can be seen from Figure 3 that the ZnIn ₂ S ₄ /KCa ₂ Nb ₃ O ₁₀ heterojunction composite material has excellent photocatalytic activity, and the CO generation rate of 20%-ZnIn ₂ S ₄ /KCa ₂ Nb ₃ O ₁₀ after five hours of reaction As high as 23.43μmol·g ^-1 , the rate of CO production per unit time is 4.69μmol·g ^-1 ·h ^-1 , and the activity is 12.31 times and 1.95 times that of monomer ZnIn ₂ S ₄ and KCa ₂ Nb ₃ O ₁₀ catalysts.

Example 2: Preparation and performance analysis of 10%-ZnIn ₂ S ₄ /KCa ₂ Nb ₃ O ₁₀ two-dimensional nanosheet heterojunction composite photocatalyst

Preparation of KCa ₂ Nb ₃ O ₁₀ nanosheets: the same method as in Example 1.

Preparation of 10%-ZnIn ₂ S ₄ /KCa ₂ Nb ₃ O ₁₀ two-dimensional nanosheet heterojunction composite photocatalytic material: 100 mg of KCa ₂ Nb ₃ O ₁₀ nanosheets, 16 mL of deionized water and 4 mL of glycerol were added to a capacity Into a 20mL round-bottomed flask, ultrasonically stirred for 30min, then added 6.41mg of ZnCl ₂ , 13.78mg of InCl ₃ 4H ₂ O and 7.11mg of thioacetamide, and stirred the above mixture for 5min, then placed in a 80°C Keep it in an oil bath for 2 hours, wait for natural cooling, centrifuge the product, wash with absolute ethanol three times, and finally place the sample in a vacuum oven at 60°C to dry the sample to obtain 10%-ZnIn ₂ S ₄ /KCa ₂ Nb ₃ O ₁₀ .

10%-ZnIn ₂ S ₄ /KCa ₂ Nb ₃ O ₁₀ two-dimensional nanosheet heterojunction composite material photocatalytic activity experiment:

(1) The photocatalytic implementation method and the product detection method are the same as in Example 1.

(2) It can be seen from Figure 3 that the CO production rate of 10%-ZnIn ₂ S ₄ /KCa ₂ Nb ₃ O ₁₀ after five hours of reaction is 18.74 μmol·g ^-1 , and the rate of CO generation per unit time is 3.75 μmol·g ^-1 h ^-1 .

Example 3:

Preparation and performance analysis of 30%-ZnIn ₂ S ₄ /KCa ₂ Nb ₃ O ₁₀ two-dimensional nanosheet heterojunction composite photocatalyst

Preparation of KCa ₂ Nb ₃ O ₁₀ nanosheets: the same method as in Example 1.

Preparation of 30%-ZnIn ₂ S ₄ /KCa ₂ Nb ₃ O ₁₀ two-dimensional nanosheet heterojunction composite photocatalytic material: 100 mg of KCa ₂ Nb ₃ O ₁₀ nanosheets, 16 mL of deionized water and 4 mL of glycerol were added to a capacity Into a 20mL round-bottomed flask, ultrasonically stirred for 30min, then added 19.23mg of ZnCl ₂ , 41.34mg of InCl ₃ ·4H ₂ O and 21.33mg of thioacetamide, and stirred the above mixture for 5min, then placed in a 80°C Keep it in an oil bath for 2 hours, wait for natural cooling, centrifuge the product, wash with absolute ethanol three times, and finally place the sample in a vacuum oven at 60°C to dry the sample to obtain 30%-ZnIn ₂ S ₄ /KCa ₂ Nb ₃ O ₁₀ .

30%-ZnIn ₂ S ₄ /KCa ₂ Nb ₃ O ₁₀ two-dimensional nanosheet heterojunction composite material photocatalytic activity experiment:

(1) The photocatalytic implementation method and the product detection method are the same as in Example 1.

(2) It can be seen from Figure 3 that the CO production rate of 30%-ZnIn ₂ S ₄ /KCa ₂ Nb ₃ O ₁₀ after five hours of reaction is 15.85 μmol·g ^-1 , and the rate of CO generation per unit time is 3.17 μmol·g ^-1 h ^-1 .

Claims (8)

1. The use of a sulfur indium zinc/calcium potassium niobate two-dimensional heterojunction composite photocatalytic material for reducing CO to prepare CO, characterized in that: sulfur indium zinc/calcium _potassium niobate two-dimensional heterojunction composite photocatalyst The preparation steps of the catalytic material are as follows: Step 1. Preparation of calcium potassium niobate KCa ₂ Nb ₃ O ₁₀ nanosheets: Weigh a certain amount of dry K ₂ CO ₃ , CaCO ₃ and Nb ₂ O ₅ in a mortar, grind and mix them thoroughly, put them in a semi-closed crucible, and then transfer the crucible to an automatic temperature-controlled tube furnace After being calcined in medium temperature, cool down to room temperature naturally, take it out, grind it into powder with a mortar, add it into HNO ₃ solution and stir for several days, and carry out protonation treatment; use deionized water and anhydrous Wash with ethanol to remove HNO ₃ , centrifuge again, and dry to obtain white solid HCa ₂ Nb ₃ O ₁₀ ; Weigh a certain amount of HCa ₂ Nb ₃ O ₁₀ , add a certain amount of tetrabutylammonium hydroxide solution and an appropriate amount of deionized water, stir for several days, and then centrifuge to obtain the upper layer of colloidal substance; then add the colloidal substance dropwise into the KCl solution to obtain a white Precipitation, the above precipitation was washed with deionized water and absolute ethanol, centrifuged, and finally placed in a vacuum drying oven to dry to obtain KCa ₂ Nb ₃ O ₁₀ nanosheets; Step 2. Preparation of ZnIn ₂ S ₄ /KCa ₂ Nb ₃ O ₁₀ two-dimensional nanosheet heterojunction composite material: Take KCa ₂ Nb ₃ O ₁₀ nanosheets and mix them in a certain amount of water and glycerol. After stirring evenly, add ZnCl ₂ , InCl ₃ 4H ₂ O and thioacetamide solids, and place the resulting mixed liquid in a round bottom Reaction in an oil bath in a flask, centrifugal washing and vacuum drying to obtain a ZnIn ₂ S ₄ /KCa ₂ Nb ₃ O ₁₀ two-dimensional nanosheet heterojunction composite material; Among them, the mass ratio of KCa ₂ Nb ₃ O ₁₀ , ZnCl ₂ , InCl ₃ ·4H ₂ O, and thioacetamide is 100:6.41-19.23:13.78-41.34:7.11-21.33. 2. The use according to claim 1, characterized in that in step 1, among the reaction raw materials K ₂ CO ₃ , CaCO ₃ and Nb ₂ O ₅ , the molar ratio of K ⁺ , Ca ²⁺ and Nb ⁵⁺ is 1.1 : 2: 3; the calcination temperature of tube furnace is 1100～1400℃, and the calcination time of tube furnace is 8～16h. 3. The use according to claim 2, characterized in that in step 1, the calcination temperature in the tube furnace is 1200°C. 4. The use according to claim 1, characterized in that in step 1, the concentration of the HNO ₃ solution is 5 mol·L ^-1 , and the protonation time is 3-5 days. 5. purposes according to claim 1, it is characterized in that, in step 1, tetrabutylammonium hydroxide solution mass fraction is 10%, and protonation product is 5～10 days in the tetrabutylammonium hydroxide solution stirring time; KCl solution The concentration is 2mol·L ^-1 . 6. The use according to claim 1, characterized in that the mass ratio of KCa ₂ Nb ₃ O ₁₀ , ZnCl ₂ , InCl ₃ ·4H ₂ O, and thioacetamide is 100:12.81:27.56:14.21. 7. The use according to claim 1, characterized in that in step 2, the reaction temperature in the oil bath is 60-100° C., and the reaction time in the oil bath is 1-3 hours. 8. The use according to claim 1, characterized in that in step 2, the vacuum temperature is 60°C, and the drying time is 24h.

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