CN116966924A - Preparation method and application of K and I co-doped composite photocatalyst - Google Patents
Preparation method and application of K and I co-doped composite photocatalyst Download PDFInfo
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- NLKNQRATVPKPDG-UHFFFAOYSA-M potassium iodide Chemical compound [K+].[I-] NLKNQRATVPKPDG-UHFFFAOYSA-M 0.000 claims abstract description 40
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- 239000004202 carbamide Substances 0.000 claims description 2
- QGBSISYHAICWAH-UHFFFAOYSA-N dicyandiamide Chemical compound NC(N)=NC#N QGBSISYHAICWAH-UHFFFAOYSA-N 0.000 claims description 2
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- 238000006116 polymerization reaction Methods 0.000 abstract 1
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- 230000000052 comparative effect Effects 0.000 description 11
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- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 description 4
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- 229910021641 deionized water Inorganic materials 0.000 description 3
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- QNGVNLMMEQUVQK-UHFFFAOYSA-N 4-n,4-n-diethylbenzene-1,4-diamine Chemical compound CCN(CC)C1=CC=C(N)C=C1 QNGVNLMMEQUVQK-UHFFFAOYSA-N 0.000 description 1
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 description 1
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- PYKYMHQGRFAEBM-UHFFFAOYSA-N anthraquinone Natural products CCC(=O)c1c(O)c2C(=O)C3C(C=CC=C3O)C(=O)c2cc1CC(=O)OC PYKYMHQGRFAEBM-UHFFFAOYSA-N 0.000 description 1
- 150000004056 anthraquinones Chemical class 0.000 description 1
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Classifications
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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
- B01J19/00—Chemical, physical or physico-chemical processes in general; Their relevant apparatus
- B01J19/08—Processes employing the direct application of electric or wave energy, or particle radiation; Apparatus therefor
- B01J19/12—Processes employing the direct application of electric or wave energy, or particle radiation; Apparatus therefor employing electromagnetic waves
- B01J19/122—Incoherent waves
- B01J19/127—Sunlight; Visible light
-
- 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
-
- C—CHEMISTRY; METALLURGY
- C01—INORGANIC CHEMISTRY
- C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
- C01B15/00—Peroxides; Peroxyhydrates; Peroxyacids or salts thereof; Superoxides; Ozonides
- C01B15/01—Hydrogen peroxide
- C01B15/027—Preparation from water
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- Chemical & Material Sciences (AREA)
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- Chemical Kinetics & Catalysis (AREA)
- Physics & Mathematics (AREA)
- Electromagnetism (AREA)
- Health & Medical Sciences (AREA)
- General Health & Medical Sciences (AREA)
- Toxicology (AREA)
- Engineering & Computer Science (AREA)
- Materials Engineering (AREA)
- Inorganic Chemistry (AREA)
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Abstract
The embodiment of the invention discloses a preparation method and application of a K and I co-doped composite photocatalyst, comprising the following steps: adding a carbon nitride precursor and alkali metal salt potassium iodide powder into a crucible according to the mass ratio of 1:0.5-8, grinding and mixing; and (3) placing the ground and mixed powder sample into a crucible, calcining at 500-600 ℃ for at least 6 hours, taking a calcined sample, grinding, placing the sample into water, stirring, centrifuging, washing and drying to obtain the K and I co-doped composite photocatalyst. The alkali metal salt potassium iodide can effectively block the polymerization of carbon nitride, so that the carbon nitride grows into a smaller size structure. The special particle shape enables the catalyst to have smaller size, larger specific surface area, stronger hydrophilicity, dispersibility and stability, and further shows excellent catalytic performances such as high activity, high selectivity and the like.
Description
Technical Field
The embodiment of the invention relates to the technical field of materials, in particular to a preparation method and application of a K and I co-doped composite photocatalyst.
Background
The hydrogen peroxide is used as an oxidant which has wide application range and is environment-friendly, and has wide application prospect in the aspects of energy, environment restoration, disinfection, sterilization, paper bleaching and the like. It has the highest active oxygen content, and the reaction by-product is only H 2 O and O 2 . At present, H is industrially produced 2 O 2 The anthraquinone cycle method is mainly adopted, and the wide application is limited by high cost, complex process, high toxicity of byproducts and the like. Therefore, it is urgent to find an efficient and low-cost hydrogen peroxide production method.
In recent years, the semiconductor photocatalysis hydrogen peroxide production by utilizing clean, pollution-free and abundant-source solar energy is an environment-friendly and sustainable approach. This technology can be performed under mild conditions (normal temperature and pressure) and does not require additional energy sources other than solar energy, and thus attracts attention of many researchers.
In addition, the graphite phase carbon nitride has the advantages of visible light response, low cost, good stability, adjustable energy band structure and the like, and is used for producing H 2 O 2 Is a promising photocatalyst candidate. However, existing bulk carbon nitrides formed by high temperature thermal polymerization exhibit severe aggregation, small specific surface area, insufficient visible light capture, rapid photo-induced electron-hole pair recombination, etc., which photo-catalytically produce H 2 O 2 Is greatly limited and has low catalytic efficiency.
Disclosure of Invention
The embodiment of the invention provides a preparation method and application of a K and I co-doped composite photocatalyst.
A preparation method of a K and I co-doped composite photocatalyst comprises the following steps:
adding a carbon nitride precursor and alkali metal salt potassium iodide powder into a crucible according to the mass ratio of 1:0.5-8, grinding and mixing;
and (3) placing the ground and mixed powder sample into a crucible, calcining at 500-600 ℃ for at least 6 hours, taking a calcined sample, grinding, placing the sample into water, stirring, centrifuging, washing and drying to obtain the K and I co-doped composite photocatalyst.
Further, the method further comprises the following steps: a method of preparing a carbon nitride precursor comprising:
sealing the precursor of the carbon nitride nano-sheet in a crucible, placing in a tube furnace, heating to 450-600 ℃ at a heating rate of 1.5-2.5 ℃/min, preserving heat for at least 6 hours, cooling the sample to room temperature at a cooling rate of 0.5-1.5 ℃/min, and grinding to obtain yellowish g-C 3 N 4 And (3) powder.
Further, the precursor of the carbon nitride nano-sheet is at least one of dicyandiamide, melamine or urea.
Further, the method further comprises the following steps:
after the mixed powder was placed in a crucible, it was wrapped with tinfoil.
An application of a K and I co-doped composite photocatalyst, comprising:
suspending the K and I co-doped composite photocatalyst prepared in claim 1 in an aqueous solution containing 5-15vol% of isopropanol, and placing O in a reaction flask 2 Bubbling for 10-50min to obtain O 2 Saturated environment;
stirring in dark for at least 30min to reach adsorption equilibrium, and performing photocatalysis in a multi-channel photocatalytic reactor at ambient temperature below 25deg.C to generate H 2 O 2 。
The embodiment of the invention has the beneficial effects that:
1. the novel K and I co-doped composite photocatalyst provided by the invention is prepared by calcining the carbon nitride precursor and the alkali metal salt potassium iodide in one pot, so that the composite material has enhanced strong visible light absorption capacity, and meanwhile, compared with single-component carbon nitride, the oxidation-reduction capacity of the composite material is obviously enhanced. Therefore, the composite photocatalyst has strong visible light absorption and oxidation-reduction capability, and is beneficial to the realization of hydrogen peroxide preparation by visible light catalysis.
2. The invention provides a novel K and I co-doped composite photocatalyst, which is a multi-element modified photocatalyst. During the thermal polymerization, potassium iodide can control the formation of carbon nitride, allowing the carbon nitride to grow into smaller size structures. The special particle shape enables the particle to have smaller size, larger specific surface area, stronger hydrophilicity, dispersibility and stability. In addition, K and I are introduced into g-C 3 N 4 In the building block, the formation of cyano groups (a nitrogen defect) can be promoted, the band gap is effectively narrowed, the conduction band is increased, and the generation and transmission of photoexcited charge carriers are improved, so that the carrier recombination is reduced, and the photocatalytic hydrogen peroxide production performance of the modified composite photocatalyst is obviously improved.
Drawings
In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings that are needed in the description of the embodiments will be briefly described below, it being obvious that the drawings in the following description are only some embodiments of the present invention, and that other drawings may be obtained according to these drawings without inventive effort for a person skilled in the art.
FIG. 1 is an XRD pattern of novel K and I co-doped composite photocatalysts of comparative examples and examples 1-3 of the present invention;
FIG. 2 is an SEM image of novel K and I co-doped composite photocatalysts of comparative examples and examples 1-3 of the present invention;
FIG. 3 is a TEM image of novel K and I co-doped composite photocatalysts of comparative examples and examples 1-3 of the present invention;
FIG. 4 is a HRTEM diagram of novel K and I co-doped composite photocatalysts of comparative examples and examples 1-3 of the present invention;
FIG. 5 is a graph of the ultraviolet visible diffuse reflectance spectrum of the novel K and I co-doped composite photocatalyst of comparative examples and examples 1-3 of the present invention;
FIG. 6 is a graph of the visible light catalyzed hydrogen peroxide production rate for the novel K and I co-doped composite photocatalyst of comparative examples and examples 1-3 of the present invention;
FIG. 7 is a graph showing the rate of hydrogen peroxide production by long-term visible light catalysis of the novel K and I co-doped composite photocatalyst of comparative examples and examples 1-3 of the present invention;
FIG. 8 is a graph showing the photocatalytic hydrogen peroxide production rates of the novel K and I co-doped composite photocatalysts of comparative examples and examples 1-3 of the present invention under different gas ambient conditions;
FIG. 9 is a graph showing the photocatalytic cycle stability of novel K and I co-doped composite photocatalysts of comparative examples and examples 1-3 of the present invention;
FIG. 10 is a calculation formula of the yield of hydrogen peroxide produced by visible light catalysis of the novel K and I co-doped composite photocatalyst of comparative example and examples 1-3 of the present invention.
Detailed Description
In order to enable those skilled in the art to better understand the present invention, the following description will make clear and complete descriptions of the technical solutions according to the embodiments of the present invention with reference to the accompanying drawings.
Comparative example
Preparing a carbon nitride nano sheet:
2g of melamine is added into a clean crucible, the crucible is sealed by aluminum foil paper and then is placed into a tube furnace, the temperature of the crucible is raised to 550 ℃ at a heating rate of 2.5 ℃/min and is kept for 6 hours, and then the sample is cooled to room temperature at a cooling rate of 1 ℃/min. Grinding the obtained yellowish sample to obtain the original g-C 3 N 4 The powder, designated CN, was compared to the K and I co-doped composite photocatalyst after modification.
Example 1
Preparing a K and I co-doped composite photocatalyst:
2g of melamine and 10g of alkali metal salt potassium iodide powder are transferred into a crucible for grinding and mixing; directly transferring the mixed powder sample into a crucible, calcining at 550 ℃ for 6 hours in a tube furnace, taking out a crude sample, grinding into powder, transferring into a beaker filled with 100ml of deionized water, stirring at room temperature for 8 hours, repeatedly washing with deionized water, centrifuging, drying, removing metal salt impurities, and obtaining the K and I co-doped composite photocatalyst, which is named CN-KI-10.
Examples 2 to 3
The preparation method of K and I co-doped composite photocatalyst in examples 2-3 is the same as that shown in example 1, except that the content of the alkali metal salt potassium iodide KI added in the S2 step is different, and the addition amount of KI in each example is shown in Table 1.
TABLE 1 KI addition in examples 2-3
| Group of | KI addition amount |
| Example 2 | 1g |
| Example 3 | 16g |
Sample characterization:
the materials of CN-KI-10, CN-KI-1, CN-KI-16 and CN prepared in example 1 were characterized to obtain XRD patterns as shown in FIG. 1, SEM as shown in FIG. 2, TEM and HRTEM patterns as shown in FIGS. 3 and 4 and UV-vis pattern as shown in FIG. 5.
The CN-KI-10 obtained in example 1 is exemplified. Two characteristic peaks of the (100) and (002) crystal planes of the carbon nitride can be simultaneously observed from the graph shown in FIG. 1, indicating g-C 3 N 4 Successful compounding. It can be observed from FIGS. 2 and 3 that CN-KI-10, which is formed after incorporation of potassium iodide, is composed of nanoparticles shaped like "rice grains" having a size of about 50-200nm, whereas the original g-C 3 N 4 Representing a large sizeBulk structure, indicating KI is able to control carbon nitride growth during calcination. Meanwhile, the lattice fringes of CN-KI-10 can be observed in the high-resolution transmission electron microscope of FIG. 4, and the measured d value is about 1.01nm, corresponding to g-C 3 N 4 The results further indicate that the addition of potassium iodide alters the morphology of the carbon nitride. FIG. 5 shows the UV-visible diffuse reflectance spectrum of CN-KI-10, showing that the composite photocatalytic material is shown to be at lambda compared to carbon nitride<The light absorption in the 480nm range is significantly enhanced.
Performance test of hydrogen peroxide production by visible light catalysis:
the hydrogen peroxide production performance test of the photocatalyst prepared in the embodiment adopts a multi-channel photocatalytic reactor (PCX 50C, perfect light Co., china) of Beijing Porphy technology Co., ltd.) and adopts a 5W LED light source (lambda is larger than or equal to 420nm,30m W/cm) 2 )。
The method comprises the following specific steps:
1. 20mg of catalyst was suspended in 40ml of aqueous solution containing 10vol% of isopropanol, O in a reaction flask 2 Bubbling for 30min to obtain O 2 Saturated environment.
2. Stirring in the dark for 30 minutes, and reaching adsorption equilibrium. Then at the ambient temperature of 25 ℃, the multi-channel photocatalytic reactor is used for photocatalysis to generate H 2 O 2 。
3. Determination of H by N, N-diethyl-1, 4-phenylenediamine 2 O 2 Is a combination of the amounts of (a) and (b).
The method comprises the following steps: 1ml of the suspension was collected every 10 minutes, filtered through a 0.22 μm water filter membrane, and the catalyst was removed. The resulting solution was then diluted about 10-50 times and an aliquot (1 mL) was mixed with 3mL of phosphate buffer, 0.3mL of DPD (10 g/L) and 0.3mL of peroxidase (POD, 1 g/L). The color of the solution changed rapidly from colorless to dark red. After shaking to make the color distribution uniform, the absorbance of the solution at 551nm was measured with an ultraviolet/visible spectrophotometer.
Wherein the phosphate buffer solution is Na 2 HPO 4 (0.1M) and NaH 2 PO 4 (0.1M) A10 g/L DPD stock solution, 10mg, was prepared by dissolving 0.1g of DPD in 10mL of deionized waterThe POD was dissolved in 10mL deionized water to prepare a 1g/L Peroxidase (POD) solution, which was stored under refrigeration. DPD and POD require fresh configuration with a maximum shelf life of no more than one week.
H 2 O 2 The concentration calculation formula is shown in fig. 10. High correlation coefficient (R 2 =0.9995), the working curve is accurate and reliable.
The test was carried out with 20mg of photocatalyst, and the test procedure was substantially the same as the photocatalytic activity test procedure, and the activity of visible light catalytic hydrogen peroxide was measured at intervals of 0 minutes by continuous illumination for 1 hour. The experimental result shows that the hydrogen peroxide production rate of the CN-KI-10 composite photocatalyst can reach 4386.4 mu mol.L after 1 hour of illumination -1 ·h -1 Has higher activity of preparing hydrogen peroxide by visible light catalysis and good photocatalytic stability.
FIG. 6 shows the effect of varying KI addition on the hydrogen peroxide production performance of a composite photocatalyst. As can be seen from FIG. 6, the hydrogen peroxide production activity of the composite photocatalyst after KI addition is compared with that of the original g-C 3 N 4 Has obvious enhancement. In addition, the addition amount of the KI and the hydrogen peroxide production performance of the composite photocatalyst are in a volcanic relation, when 10g of the KI is doped, the hydrogen peroxide production performance of the composite photocatalyst is highest, and when the load amount is continuously increased, the hydrogen peroxide production performance of the composite photocatalyst is gradually reduced.
Fig. 7 shows the hydrogen peroxide production of the composite photocatalyst as a function of time. As can be seen from fig. 7, the hydrogen peroxide production of the composite photocatalyst tends to increase linearly with time, and to stabilize after 8 hours. By way of comparison, FIG. 8 shows the hydrogen peroxide production rate of the composite photocatalyst CN-KI-10 in different gas atmospheres when 10g of KI is incorporated. It can be seen that CN-KI-10 produces H under visible light in an oxygen-filled atmosphere 2 O 2 The rate was highest, the yield was significantly reduced in an air atmosphere, and almost completely suppressed in an argon atmosphere. Indicating that CN-KI-10 has greater potential for preparing hydrogen peroxide by photocatalysis under the condition of oxygen saturation.
Photocatalytic stability test:
the best performance is selectedCN-KI-10 samples of (c) as subjects of the cycling test. After the test is completed, the catalyst is washed and centrifugally separated for repeated use, and the sample is put into the reactor again and is aerated for 30 minutes to reach an oxygen saturation state. The light irradiation was then continued and the cycle test was repeated 4 times in total to test the light stability, resulting in the results shown in fig. 9. As shown, the CN-KI-10 samples remained stable for at least four photocatalytic runs. At the same time, it can be observed that H in the fourth run compared to the first run 2 O 2 The concentration is only slightly reduced. The significant decrease in photocatalytic performance corresponds to the loss of photocatalyst due to friction in the stirred photocatalytic reaction and multiple photocatalyst recovery. The result shows that the prepared CN-KI-10 photocatalyst has better cycle performance and physical and chemical stability.
It is apparent that the above examples are given by way of illustration only and are not limiting of the embodiments. Other variations or modifications of the above teachings will be apparent to those of ordinary skill in the art. It is not necessary here nor is it exhaustive of all embodiments. While still being apparent from variations or modifications that may be made by those skilled in the art are within the scope of the invention.
The foregoing is only a partial embodiment of the present invention, and it should be noted that it will be apparent to those skilled in the art that modifications and adaptations can be made without departing from the principles of the present invention, and such modifications and adaptations are intended to be comprehended within the scope of the present invention.
Claims (5)
1. The preparation method of the K and I co-doped composite photocatalyst is characterized by comprising the following steps of:
adding a carbon nitride precursor and alkali metal salt potassium iodide powder into a crucible according to the mass ratio of 1:0.5-8, grinding and mixing;
and (3) placing the ground and mixed powder sample into a crucible, calcining at 500-600 ℃ for at least 6 hours, taking a calcined sample, grinding, placing the sample into water, stirring, centrifuging, washing and drying to obtain the K and I co-doped composite photocatalyst.
2. The method of manufacturing according to claim 1, further comprising: a method of preparing a carbon nitride precursor comprising:
sealing the precursor of the carbon nitride nano-sheet in a crucible, placing in a tube furnace, heating to 450-600 ℃ at a heating rate of 1.5-2.5 ℃/min, preserving heat for at least 6 hours, cooling the sample to room temperature at a cooling rate of 0.5-1.5 ℃/min, and grinding to obtain yellowish g-C 3 N 4 And (3) powder.
3. The method according to claim 2, wherein the precursor of the carbon nitride nanosheets is at least one of dicyandiamide, melamine or urea.
4. The method of manufacturing according to claim 1, further comprising:
after the mixed powder was placed in a crucible, it was wrapped with tinfoil.
5. Use of a K and I co-doped composite photocatalyst, comprising:
suspending the K and I co-doped composite photocatalyst prepared in claim 1 in an aqueous solution containing 5-15vol% of isopropanol, and placing O in a reaction flask 2 Bubbling for 10-50min to obtain O 2 Saturated environment;
stirring in dark for at least 30min to reach adsorption equilibrium, and performing photocatalysis in a multi-channel photocatalytic reactor at ambient temperature below 25deg.C to generate H 2 O 2 。
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202310944906.8A CN116966924A (en) | 2023-07-28 | 2023-07-28 | Preparation method and application of K and I co-doped composite photocatalyst |
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