Thiazole ring modified C3N4 / C3N5 heterojunction photocatalyst as well as preparation method and application thereof

Abstract

The invention discloses a preparation method of a thiazole ring modified C3N4 / C3N5 heterojunction photocatalyst, which comprises the following steps: weighing a certain amount of C3N4 raw material, C3N5 raw material and thiazole raw material, adding into deionized water, fully stirring and dissolving, evaporating, drying, and grinding to obtain a mixture precursor; calcining the obtained mixture precursor at a certain temperature, cooling to room temperature, and grinding; the obtained sample is repeatedly washed with deionized water and absolute ethyl alcohol until supernate is colorless, then centrifugation, drying and grinding are conducted in sequence, and the obtained sample is the thiazole ring modified C3N4 / C3N5 heterojunction photocatalyst. The method is simple in preparation process, low in energy consumption and easy to industrialize, and the prepared thiazole ring modified C3N4 / C3N5 heterojunction photocatalyst is applied to production of H2O2 and can have high photocatalytic activity.

Description

Technical Field

[0001] The present invention belongs to the technical field of catalyst preparation, and specifically relates to a thiazole ring modified C3N4 / C3N5 heterojunction photocatalyst and a preparation method and application thereof. Background Art

[0002] Hydrogen peroxide (H2O2) is an environmentally friendly oxidant and is considered one of the most useful chemicals in the chemical industry. It is also an important liquid fuel with a higher energy density than hydrogen (35MPa). The traditional anthraquinone oxidation process to produce H2O2 produces a large amount of organic waste streams, which is harmful to the environment. Producing H2O2 from water and oxygen through artificial photosynthesis is a very promising method.

[0003] The main pathway for photocatalytic synthesis of H2O2 is the O2 reduction reaction (ORR) that occurs on the surface of semiconductor photocatalysts. Photogenerated electron-hole pairs separate and participate in the ORR process. However, factors such as the high electron-hole pair recombination rate, poor visible light response, and low product selectivity of photocatalysts severely limit the efficiency of photocatalytic synthesis of H2O2. The development of efficient and low-cost photocatalysts is the key.

[0004] Graphitic carbon nitride is a metal-free polymer semiconductor with unique properties and good chemical stability, and can effectively absorb visible light. However, bulk carbon nitride has some defects, such as high recombination rate of photogenerated electrons and holes, low visible light utilization, and few oxygen reduction active sites.

[0005] In order to overcome these shortcomings of graphite carbon nitride, graphite carbon nitride can be modified, such as building a heterostructure, morphology control, defect modification, element doping, functional group modification and other methods to improve the photocatalytic performance of graphite carbon nitride. However, the construction of heterojunctions requires fine control of interfaces and contacts, and there may be problems of interface mismatch or poor contact; morphology control may require complex templates or external structure guidance, and the preparation process is relatively cumbersome; defect modification and element doping are difficult to accurately control the defect type and defect / heteroatom concentration. Functional group modification not only helps to change the surface properties of graphite carbon nitride, but also can adjust its band structure, thereby optimizing performance. Summary of the invention

[0006] The purpose of the present invention is to provide a thiazole ring modified C3N4 / C3N5 heterojunction photocatalyst and its preparation method and application. The method has a simple preparation process, low energy consumption, and is easy to industrialize. The prepared thiazole ring modified C3N4 / C3N5 heterojunction photocatalyst is applied to the production of H2O2 and can have high photocatalytic activity.

[0007] To achieve the above object, the technical solution adopted by the present invention is: a method for preparing a thiazole ring modified C3N4 / C3N5 heterojunction photocatalyst, comprising the following steps:

[0008] S1. Weigh a certain amount of C3N4 raw materials, C3N5 raw materials and thiazole raw materials, add them into deionized water, stir and dissolve them, evaporate, dry and grind to obtain a mixture precursor;

[0009] S2, calcining the mixture precursor obtained in step S1 at a certain temperature, then cooling to room temperature, and grinding;

[0010] S3. The sample obtained in step S2 is repeatedly washed with deionized water and anhydrous ethanol until the supernatant is colorless, and then centrifuged, dried, and ground in sequence. The obtained sample is a thiazole ring-modified C3N4 / C3N5 heterojunction photocatalyst.

[0011] Preferably, in step S1, the raw material of C3N4 is one or two of urea, melamine, cyanuric acid, dicyandiamide, cyanamide, and thiourea.

[0012] Preferably, in step S1, the raw material of C3N5 is one or two of 3-amino-1,2,4-triazole, melem, 5-amino-1H-tetrazole, and 2,4,6-trihydrazino-1,3,5-triazine.

[0013] Preferably, in step S1, the thiazole raw material is one of thiazole-4-carboxaldehyde, benzothiazole-2-carboxaldehyde, thiazole-4-carboxylic acid, 2-acetylthiazole, and 2-formylthiazole.

[0014] Preferably, in step S1, the mass ratio between the total mass of the raw materials of C3N4 and C3N5 and the thiazole raw material is 100:(0.1-5).

[0015] Preferably, in step S1, the mass ratio of C3N4 raw material to C3N5 raw material is (0.1-10):1.

[0016] Preferably, in step S2, the calcination temperature is 400° C. to 600° C.; and the calcination time is 0.5 h to 5 h.

[0017] Preferably, in step S2, the calcination atmosphere is one of air, nitrogen and argon.

[0018] To achieve the above objectives, the present invention also provides a thiazole ring-modified C3N4 / C3N5 heterojunction photocatalyst prepared by the above preparation method.

[0019] To achieve the above object, the present invention also provides the use of the thiazole ring modified C3N4 / C3N5 heterojunction photocatalyst prepared by the above preparation method in the production of H2O2.

[0020] Compared with the prior art, the present invention has the following beneficial effects:

[0021] The thiazole ring modified C3N4 / C3N5 heterojunction photocatalyst prepared by the present invention effectively improves the light absorption / utilization efficiency of the composite catalyst; wherein, the modification of the thiazole ring can cause electron delocalization of the carbon nitride ring, accelerating the separation of photogenerated electron-hole pairs; in addition, the C3N4 phase and the C3N5 phase present in the composite form a heterojunction, which can further inhibit the recombination of photogenerated carriers and effectively enhance the photocatalytic activity. The method has a simple preparation process, low energy consumption, and is easy to realize industrialization. The prepared thiazole ring modified C3N4 / C3N5 heterojunction photocatalyst significantly improves the photocatalytic reduction performance of oxygen under visible light irradiation, and effectively produces hydrogen peroxide. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 This is a SEM image of the thiazole ring modified C3N4 / C3N5 heterojunction photocatalyst prepared in Example 1;

[0023] Figure 2 TEM image (a) and corresponding element distribution map (b) of the thiazole ring modified C3N4 / C3N5 heterojunction photocatalyst prepared in Example 1;

[0024] Figure 3 The XPS spectra of the catalysts prepared in Comparative Example 1 and Example 1 are respectively;

[0025] Figure 4 This is a high-resolution S2p XPS spectrum of the thiazole ring-modified C3N4 / C3N5 heterojunction photocatalyst prepared in Example 1;

[0026] Figure 5 It is a comparison chart of the photocatalytic H2O2 production performance results of the catalysts prepared in Comparative Examples 1-3 and Example 1 respectively. DETAILED DESCRIPTION

[0027] The present invention is further described in detail below with reference to the accompanying drawings and specific embodiments.

[0028] All raw materials and reagents in the examples of the present application were purchased on the market or prepared according to conventional methods well known to those skilled in the art.

[0029] Example 1

[0030] A method for preparing a thiazole ring modified C3N4 / C3N5 heterojunction photocatalyst comprises the following steps:

[0031] S1. Weigh melamine and 3-amino-1,2,4-triazole at a mass ratio of 1:1, weigh benzothiazole-2-carboxaldehyde at a mass ratio of 100:0.1 between the total mass of melamine and 3-amino-1,2,4-triazole and benzothiazole-2-carboxaldehyde, add them into deionized water, stir them to dissolve, evaporate, dry and grind them to obtain a mixture precursor;

[0032] S2, calcining the mixture precursor obtained in step S1 at 550° C. for 2 h, then cooling to room temperature and grinding;

[0033] S3. The sample obtained in step S2 is repeatedly washed with deionized water and anhydrous ethanol until the supernatant is colorless, centrifuged, dried in a vacuum drying oven, and ground. The obtained sample is a thiazole ring-modified C3N4 / C3N5 heterojunction photocatalyst.

[0034] from Figure 1 It can be seen that the sample prepared in this embodiment generally presents a lamellar structure.

[0035] from Figure 2 As can be seen in (a), the detection of the S element is due to the introduction of the thiazole ring into the material structure; Figure 2 It can be seen from (b) that the elements C, N, O, S, etc. in the sample prepared in this embodiment are evenly distributed in the material structure.

[0036] from Figure 3 and Figure 4 It can be seen that, compared with Comparative Example 1, this embodiment successfully introduces the S element.

[0037] Example 2

[0038] A method for preparing a thiazole ring modified C3N4 / C3N5 heterojunction photocatalyst comprises the following steps:

[0039] S1. Weigh urea and 3-amino-1,2,4-triazole at a mass ratio of 5:1, weigh thiazole-4-carboxaldehyde at a mass ratio of 100:5 of the total mass of urea and 3-amino-1,2,4-triazole to thiazole-4-carboxaldehyde, add them into deionized water, stir and dissolve them, evaporate, dry and grind to obtain a mixture precursor;

[0040] S2, calcining the mixture precursor obtained in step S1 at 550° C. for 1 h, then cooling to room temperature and grinding;

[0041] S3. The sample obtained in step S2 is repeatedly washed with deionized water and anhydrous ethanol until the supernatant is colorless, centrifuged, dried in a vacuum drying oven, and ground. The obtained sample is a thiazole ring-modified C3N4 / C3N5 heterojunction photocatalyst.

[0042] Example 3

[0043] A method for preparing a thiazole ring modified C3N4 / C3N5 heterojunction photocatalyst comprises the following steps:

[0044] S1. Weigh cyanuric acid and melem at a mass ratio of 10:1, weigh thiazole-4-carboxylic acid at a mass ratio of the total mass of cyanuric acid and melem to thiazole-4-carboxylic acid of 100:0.5, add them to deionized water, stir and dissolve them, evaporate, dry and grind to obtain a mixture precursor;

[0045] S2, calcining the mixture precursor obtained in step S1 at 600° C. for 0.5 h, then cooling to room temperature and grinding;

[0046] S3. The sample obtained in step S2 is repeatedly washed with deionized water and anhydrous ethanol until the supernatant is colorless, centrifuged, dried in a vacuum drying oven, and ground. The obtained sample is a thiazole ring-modified C3N4 / C3N5 heterojunction photocatalyst.

[0047] Example 4

[0048] A method for preparing a thiazole ring modified C3N4 / C3N5 heterojunction photocatalyst comprises the following steps:

[0049] S1. Weigh dicyandiamide and 5-amino-1H-tetrazole at a mass ratio of 1:3, weigh 2-acetylthiazole at a mass ratio of 100:0.1 of the total mass of dicyandiamide and 5-amino-1H-tetrazole to 2-acetylthiazole, add them to deionized water, stir and dissolve them, evaporate, dry and grind to obtain a mixture precursor;

[0050] S2, calcining the mixture precursor obtained in step S1 at 400° C. for 5 h, then cooling to room temperature and grinding;

[0051] S3. The sample obtained in step S2 is repeatedly washed with deionized water and anhydrous ethanol until the supernatant is colorless, centrifuged, dried in a vacuum drying oven, and ground. The obtained sample is a thiazole ring-modified C3N4 / C3N5 heterojunction photocatalyst.

[0052] Example 5

[0053] A method for preparing a thiazole ring modified C3N4 / C3N5 heterojunction photocatalyst comprises the following steps:

[0054] S1. Weigh thiourea and 2,4,6-trihydrazino-1,3,5-triazine at a mass ratio of 1:10, weigh 2-formylthiazole at a mass ratio of 100:1 of the total mass of thiourea and 2,4,6-trihydrazino-1,3,5-triazine to 2-formylthiazole, add them into deionized water, stir them to dissolve, evaporate, dry and grind to obtain a mixture precursor;

[0055] S2, calcining the mixture precursor obtained in step S1 at 500° C. for 3 h, then cooling to room temperature and grinding;

[0056] S3. The sample obtained in step S2 is repeatedly washed with deionized water and anhydrous ethanol until the supernatant is colorless, centrifuged, dried in a vacuum drying oven, and ground. The obtained sample is a thiazole ring-modified C3N4 / C3N5 heterojunction photocatalyst.

[0057] Example 6

[0058] A method for preparing a thiazole ring modified C3N4 / C3N5 heterojunction photocatalyst comprises the following steps:

[0059] S1. Weigh cyanamide and 3-amino-1,2,4-triazole at a mass ratio of 1:1, weigh benzothiazole-2-carboxaldehyde at a mass ratio of 100:0.1 of the total mass of cyanamide and 3-amino-1,2,4-triazole to benzothiazole-2-carboxaldehyde, add them into deionized water, stir them to dissolve, evaporate, dry and grind to obtain a mixture precursor;

[0060] S2, calcining the mixture precursor obtained in step S1 at 550° C. for 2 h, then cooling to room temperature and grinding;

[0061] S3. The sample obtained in step S2 is repeatedly washed with deionized water and anhydrous ethanol until the supernatant is colorless, centrifuged, dried in a vacuum drying oven, and ground. The obtained sample is a thiazole ring-modified C3N4 / C3N5 heterojunction photocatalyst.

[0062] Comparative Example 1

[0063] A method for preparing a C3N4 / C3N5 heterojunction material comprises the following steps:

[0064] S1. Weigh melamine and 3-amino-1,2,4-triazole in a mass ratio of 1:1, add them into deionized water, stir and dissolve them, evaporate and dry them, and grind them to form a mixture precursor;

[0065] S2, calcining the mixture precursor obtained in step S1 at 550° C. for 2 h, then cooling to room temperature and grinding;

[0066] S3. The sample obtained in step S2 is repeatedly washed with deionized water and anhydrous ethanol until the supernatant is colorless, centrifuged, placed in a vacuum drying oven to dry, and ground. The obtained sample is the C3N4 / C3N5 heterojunction material.

[0067] Comparative Example 2

[0068] A method for preparing thiazole ring-modified C3N4 comprises the following steps:

[0069] S1. Weigh melamine and benzothiazole-2-carboxaldehyde in a mass ratio of 100:0.5, add them into deionized water, stir and dissolve them, evaporate and dry them, and grind them to form a mixture precursor;

[0070] S2, calcining the mixture precursor obtained in step S1 at 550° C. for 2 h, cooling it to room temperature, and grinding it;

[0071] S3. The obtained sample is repeatedly washed with deionized water and anhydrous ethanol until the supernatant is colorless, centrifuged, placed in a vacuum drying oven to dry, and ground. The obtained sample is C3N4 modified with a thiazole ring.

[0072] Comparative Example 3

[0073] A method for preparing thiazole ring-modified C3N5 comprises the following steps:

[0074] S1. Weigh 3-amino-1,2,4-triazole and benzothiazole-2-carboxaldehyde in a mass ratio of 100:0.5, add them into deionized water, stir and dissolve them, evaporate and dry them, and grind them to form a mixture precursor;

[0075] S2, calcining the mixture precursor obtained in step S1 at 550° C. for 2 h, cooling it to room temperature, and grinding it;

[0076] S3. The obtained sample is repeatedly washed with deionized water and anhydrous ethanol until the supernatant is colorless, centrifuged, placed in a vacuum drying oven to dry, and ground. The obtained sample is thiazole ring-modified C3N5.

[0077] In order to further test the photocatalytic activity of the product prepared in the example, the photocatalytic hydrogen peroxide production experiment process is as follows:

[0078] The photocatalyst (30 mg) was dispersed in a quartz reaction vessel containing a mixture of 100 ml of ethanol and deionized water (volume ratio of 1:9). High-purity oxygen was first introduced into the reaction solution in the dark and stirred for 30 minutes to saturate the solution with oxygen. Then, the reaction solution was illuminated by a 300 W xenon lamp (420 nm, 150 mW cm -2) for 1.5 hours, sampling was performed every 15 minutes, and the H2O2 concentration in the solution was detected by iodine titration.

[0079] from Figure 5 It can be seen that the photocatalyst prepared in Example 1 can produce 513 umol / L of H2O2 within 90 minutes, which is approximately 2.2 times, 1.4 times, and 1.7 times that of Comparative Example 1, Comparative Example 2, and Comparative Example 3, respectively. It can be seen that the photocatalyst prepared by the present invention has excellent photocatalytic activity in the photocatalytic production of H2O2.

Claims

1. A method for preparing a thiazole ring modified C3N4 / C3N5 heterojunction photocatalyst, characterized in that: The following steps are involved: S1. Weigh a certain amount of C3N4 raw materials, C3N5 raw materials and thiazole raw materials, add them into deionized water, stir and dissolve them, evaporate, dry and grind to obtain a mixture precursor; S2, calcining the mixture precursor obtained in step S1 at a certain temperature, then cooling to room temperature, and grinding; S3. The sample obtained in step S2 is repeatedly washed with deionized water and anhydrous ethanol until the supernatant is colorless, and then centrifuged, dried, and ground in sequence. The obtained sample is a thiazole ring-modified C3N4 / C3N5 heterojunction photocatalyst.

2. The method for preparing a thiazole ring modified C3N4 / C3N5 heterojunction photocatalyst according to claim 1, characterized in that: In step S1, the raw materials of C3N4 are one or two of urea, melamine, cyanuric acid, dicyandiamide, cyanamide, and thiourea.

3. The method for preparing a thiazole ring modified C3N4 / C3N5 heterojunction photocatalyst according to claim 1 or 2, characterized in that: In step S1, the raw materials of C3N5 are one or two of 3-amino-1,2,4-triazole, melem, 5-amino-1H-tetrazole, and 2,4,6-trihydrazino-1,3,5-triazine.

4. The method for preparing a thiazole ring modified C3N4 / C3N5 heterojunction photocatalyst according to claim 1 or 2, characterized in that: In step S1, the thiazole raw material is one of thiazole-4-carboxaldehyde, benzothiazole-2-carboxaldehyde, thiazole-4-carboxylic acid, 2-acetylthiazole, and 2-formylthiazole.

5. The method for preparing a thiazole ring modified C3N4 / C3N5 heterojunction photocatalyst according to claim 1 or 2, characterized in that: In step S1, the mass ratio between the total mass of the raw materials of C3N4 and C3N5 and the thiazole raw material is 100:(0.1-5).

6. The method for preparing a thiazole ring modified C3N4 / C3N5 heterojunction photocatalyst according to claim 1 or 2, characterized in that: In step S1, the mass ratio of C3N4 raw material to C3N5 raw material is (0.1-10):

1.

7. The method for preparing a thiazole ring modified C3N4 / C3N5 heterojunction photocatalyst according to claim 1 or 2, characterized in that: In step S2, the calcination temperature is 400°C to 600°C; and the calcination time is 0.5h to 5h.

8. The method for preparing a thiazole ring modified C3N4 / C3N5 heterojunction photocatalyst according to claim 1 or 2, characterized in that: In step S2, the calcination atmosphere is one of air, nitrogen and argon.

9. A thiazole ring modified C3N4 / C3N5 heterojunction photocatalyst prepared according to any one of the preparation methods described in claims 1-8.

10. Use of the thiazole ring modified C3N4 / C3N5 heterojunction photocatalyst according to claim 9 in the production of H2O2.

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