Preparation method of iodine-doped carbon nitride microrod, carbon nitride microrod and application

Abstract

The invention discloses a preparation method of an iodine-doped carbon nitride microrod. The preparation method comprises the following steps: S1, preparing a carbon nitride nanosheet by a step-by-step pyrolysis method; s2, respectively adding the carbon nitride nanosheets and cyanuric acid into deionized water to obtain a cyanuric acid solution and a carbon nitride dispersion liquid; s3, slowly dropwise adding a cyanuric acid solution into the carbon nitride dispersion liquid to obtain a mixed system, then adding an iodine compound into the mixed system, and carrying out a hydrothermal reaction; and S4, carrying out solid-liquid separation on the product of the hydrothermal reaction, and drying and grinding the solid to obtain the iodine-doped carbon nitride microrod. According to the iodine-doped carbon nitride microrod, carbon nitride prepared through a step-by-step pyrolysis method serves as a base material, iodine with high electronegativity is doped into carbon nitride, the iodine-doped microrod is obtained through self-assembly, the hydrothermal reaction production condition is mild, and the iodine-doped carbon nitride microrod has higher catalytic activity. The invention further discloses the iodine-doped carbon nitride microrod and application thereof.

Description

Technical Field

[0001] The invention relates to the technical field of photocatalyst carbon nitride, and in particular to a preparation method of iodine-doped carbon nitride microrods, the carbon nitride microrods and applications. Background Art

[0002] Carbon nitride is a low-cost, chemically stable, narrow bandgap (λ> 420 nm), and strong visible light response. It is widely used in photocatalytic fields, such as photocatalytic hydrogen production from water, degradation of organic pollutants, and reduction of carbon dioxide. However, due to the shortcomings of g-C3N4, such as a large bandgap (2.7 eV), easy recombination of electrons and holes, and a small specific surface area, its application in the field of photocatalysis is greatly restricted. Improved methods include structural regulation, doping modification, and heterojunction design.

[0003] Structural regulation is mainly achieved by using templates and / or optimizing process parameters, with nano-scale powders being the modification direction, to obtain carbon nitride structures with larger areas and more mesopores, such as honeycomb, velvet, and hollow multilayer flower shapes.

[0004] Among the known structures of photocatalysts, the microrod structure has a higher aspect ratio, a shorter path and lower resistance during electron transport, and better conductivity; the anisotropic structure of the microrod can provide unique optical and electrical properties. Therefore, the photocatalyst with a microrod structure has a higher reaction efficiency in the catalytic and adsorption processes.

[0005] CN113908872A discloses a divacancy graphite phase carbon nitride photocatalyst, which is prepared by mixing melamine and cyanuric acid, hydrothermal reaction, freeze drying, and high-temperature calcination in H2 atmosphere. The carbon nitride photocatalyst contains both carbon vacancies and nitrogen vacancies. However, the above method is cumbersome and complicated to prepare, the diameter of the microrods obtained is small, the last step of high-temperature calcination has the problem of agglomeration of the microrods, and there are still disadvantages of low visible light response and rapid photoinduced charge recombination. Summary of the invention

[0006] One of the purposes of the present invention is to overcome the defects existing in the prior art and provide a method for preparing iodine-doped carbon nitride microrods, based on the carbon nitride prepared by the step-by-step pyrolysis method to prepare iodine-doped carbon nitride microrods with higher photocatalytic performance.

[0007] In order to achieve the above technical effects, the technical solution of the present invention is: a method for preparing iodine-doped carbon nitride microrods, comprising the following steps: S1: Preparation of carbon nitride nanosheets by step-by-step pyrolysis; S2: adding carbon nitride nanosheets and cyanuric acid into deionized water to obtain cyanuric acid solution and carbon nitride dispersion; S3: slowly dropping the cyanuric acid solution into the carbon nitride dispersion to obtain a mixed system, and then adding an iodine compound to the mixed system for a hydrothermal reaction; S4: The products of the hydrothermal reaction are separated into solid and liquid, and the solid is dried and ground to obtain iodine-doped carbon nitride microrods.

[0008] The preferred technical solution is that the mass ratio of the carbon nitride nanosheets in the carbon nitride dispersion to the cyanuric acid in the cyanuric acid solution is 1:(9-16.2), which can be specifically selected as 1:9, 1:9.5, 1:10, 1:10.5, 1:11, 1:11.5, 1:12, 1:12.2, 1:14, 1:12.5, 1:12.6, 1:12.8, 1:13, 1:13.5, 1:14, 1:14.5, 1:15, 1:15.5, 1:16, 1:16.2 point values ​​and an interval with two point values ​​as the maximum and minimum values, further preferably 1:(9.5-15), and even more preferably 1:(10.5-14.2). Based on a predetermined amount of carbon nitride nanosheets, if there is too much cyanuric acid, the morphology of the obtained iodine-doped carbon nitride is blocky; if there is too little cyanuric acid, the morphology of the iodine-doped carbon nitride retains the original broken layered structure of the carbon nitride in S1.

[0009] The preferred technical solution is that the mass ratio of carbon nitride nanosheets to iodine compounds in the carbon nitride dispersion is 1:(15-23), and can be specifically selected as 1:15, 1:16, 1:17, 1:18, 1:19, 1:20, 1:21, 1:22, 1:23 point values ​​and an interval with two point values ​​as the maximum and minimum values; further preferably 1:(17.5-22), and even more preferably 1:(18-20.5).

[0010] The preferred technical solution is that the hydrothermal reaction temperature is 160-200° C. and the reaction time is 5-9 hours.

[0011] The hydrothermal reaction temperature can be selected from 160°C, 165°C, 175°C, 175°C, 180°C, 185°C, 190°C, 195°C, 200°C and an interval with two points as the maximum and minimum values; more preferably, 165-195°C, and even more preferably, 170-190°C.

[0012] The hydrothermal reaction time can be selected as 5h, 5.5h, 6h, 6.5h, 7h, 7.5h, 8h, 8.5h, 9h and an interval with two points as the maximum and minimum values; more preferably 5.5-8.5h, and further preferably 6-8.5h.

[0013] A preferred technical solution is that the iodine compound is ammonium iodide.

[0014] The preferred technical solution is that the thickness of the carbon nitride nanosheets in S1 is 10 to 300 nm, which can be selected as 10 nm, 50 nm, 100 nm, 150 nm, 200 nm, 250 nm, 300 nm point values ​​and an interval with two point values ​​as the maximum and minimum values, and is further preferably 50 to 200 nm.

[0015] The preferred technical solution is that the length of the iodine-doped carbon nitride microrods is 3-10 μm and the diameter is 2-3 μm. The longer the length of the iodine-doped carbon nitride microrods is within the above preferred range, the higher the catalytic activity of the photocatalyst.

[0016] The second object of the present invention is to provide an iodine-doped carbon nitride microrod, which is prepared by the above-mentioned method for preparing iodine-doped carbon nitride microrod.

[0017] The third object of the present invention is to provide an application of iodine-doped carbon nitride microrods as a photocatalyst in a photocatalytic reaction. Furthermore, the photocatalytic reaction includes photocatalytic hydrogen production.

[0018] The advantages and beneficial effects of the present invention are: The iodine-doped carbon nitride microrods are based on broken nano-sheet carbon nitride prepared by a step-by-step pyrolysis method. Iodine with high electronegativity is doped into the carbon nitride by a hydrothermal reaction. At the same time, the nanosheets are self-assembled to obtain microrods. The above substrates are agglomerated by a hydrothermal reaction, avoiding the agglomeration problem of the microrods produced by calcining, which is conducive to controlling the morphology of the carbonized nitrogen product. The iodine-doped carbon nitride microrods prepared by the optimal process parameters effectively adjust the electronic structure of the material, optimize the conductivity and semiconductor properties; improve the selectivity and activity of the catalyst, and accelerate the reaction rate of specific photocatalytic reactions. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 is a SEM image of iodine-doped carbon nitride microrods of Example 1; Figure 2 is the XRD pattern of iodine-doped carbon nitride microrods of Example 1; Figure 3 are solid ultraviolet and bandgap width diagrams of carbon nitride nanosheets and carbon nitride microrods before and after modification in Example 1; Figure 4 It is a comparison chart of the hydrogen production performance of the catalysts obtained in Examples 1-9. DETAILED DESCRIPTION

[0020] The specific implementation of the present invention is further described below in conjunction with the examples. The following examples are only used to more clearly illustrate the technical solutions of the present invention, and cannot be used to limit the protection scope of the present invention.

[0021] In the following description, many specific details are set forth to facilitate a full understanding of the present invention, but the present invention may also be implemented in other ways different from those described herein, and those skilled in the art may make similar generalizations without violating the connotation of the present invention. Therefore, the present invention is not limited to the specific embodiments disclosed below.

[0022] Secondly, the term "one embodiment" or "embodiment" as used herein refers to a specific feature, structure, or characteristic that may be included in at least one implementation of the present invention. The term "in one embodiment" that appears in different places in this specification does not necessarily refer to the same embodiment, nor does it refer to a separate or selective embodiment that is mutually exclusive with other embodiments.

[0023] Unless otherwise specified, the raw materials used in the examples are all purchased commercially. The stepwise pyrolysis method includes known steps such as gradually increasing the temperature, maintaining the temperature, naturally cooling to room temperature, grinding, washing, and drying. The thickness of the broken carbon nitride nanosheets prepared by the stepwise pyrolysis method is 100 nm.

[0024] Example 1

[0025] (1) 0.1 g of carbon nitride nanosheets and 1.26 g of cyanuric acid were added to a certain amount of 85 °C deionized water and mixed to obtain a cyanuric acid solution and a carbon nitride dispersion; (2) slowly adding the cyanuric acid solution obtained in step (1) dropwise to the carbon nitride dispersion, and then adding 1.9 g of ammonium iodide; (3) The mixed solution in step (2) was transferred to a 200 mL reactor and the temperature of the reactor was raised to 180 °C; (4) The reactor in step (3) was kept at 180°C for 8 h, the product was filtered and washed with deionized water, dried and ground to obtain iodine-doped carbon nitride microrods with a length of 3 to 10 µm and a diameter of about 2 to 3 µm.

[0026] The SEM image of the iodine-doped carbon nitride microrods obtained in Example 1 is as follows: Figure 1 As shown; XRD pattern as Figure 2 As shown; the solid ultraviolet and bandgap width of carbon nitride nanosheets and carbon nitride microrods are shown Figure 3 shown.

[0027] Example 2

[0028] (1) 0.1 g of carbon nitride nanosheets and 2.26 g of cyanuric acid were added to a certain amount of 85 °C deionized water and mixed; (2) slowly adding the cyanuric acid solution obtained in step (1) dropwise to the carbon nitride dispersion, and then adding 1.9 g of ammonium iodide; (3) The mixed solution in step (2) was transferred to a 200 mL reactor and the temperature of the reactor was raised to 180 °C; (4) The reactor in step (3) is kept at 180° C. for 8 h, the obtained product is filtered and washed with deionized water, dried and ground to obtain iodine-doped bulk carbon nitride.

[0029] Example 3

[0030] (1) 0.1 g of carbon nitride nanosheets and 0.26 g of cyanuric acid were added to a certain amount of 85 °C deionized water and mixed; (2) slowly adding the cyanuric acid solution obtained in step (1) dropwise to the carbon nitride dispersion, and then adding 1.9 g of ammonium iodide; (3) The mixed solution in step (2) was transferred to a 200 mL reactor and the temperature of the reactor was raised to 180 °C; (4) The reactor in step (3) is kept at 180° C. for 8 h, the obtained product is filtered and washed with deionized water, dried and ground to obtain iodine-doped bulk carbon nitride.

[0031] Example 4

[0032] (1) 0.1 g of carbon nitride nanosheets and 1.26 g of cyanuric acid were added to a certain amount of 85 °C deionized water and mixed; (2) slowly adding the cyanuric acid solution obtained in step (1) dropwise to the carbon nitride dispersion, and then adding 2.9 g of ammonium iodide; (3) The mixed solution in step (2) was transferred to a 200 mL reactor and the temperature of the reactor was raised to 180 °C; (4) The reactor in step (3) is kept at 180° C. for 8 h, the obtained product is filtered and washed with deionized water, dried and ground to obtain iodine-doped bulk carbon nitride.

[0033] Example 5

[0034] (1) 0.1 g of carbon nitride nanosheets and 1.26 g of cyanuric acid were added to a certain amount of 85 °C deionized water and mixed; (2) slowly adding the cyanuric acid solution obtained in step (1) dropwise to the carbon nitride dispersion, and then adding 0.9 g of ammonium iodide; (3) The mixed solution in step (2) was transferred to a 200 mL reactor and the temperature of the reactor was raised to 180 °C; (4) The reactor in step (3) is kept at 180° C. for 8 h, the obtained product is filtered and washed with deionized water, dried and ground to obtain iodine-doped bulk carbon nitride.

[0035] Example 6

[0036] (1) 0.1 g of carbon nitride nanosheets and 1.26 g of cyanuric acid were added to a certain amount of 85 °C deionized water and mixed; (2) slowly adding the cyanuric acid solution obtained in step (1) dropwise to the carbon nitride dispersion, and then adding 1.9 g of ammonium iodide; (3) The mixed solution in step (2) was transferred to a 200 mL reactor and the temperature of the reactor was raised to 280 °C; (4) The reactor in step (3) is kept at 280° C. for 8 h, the obtained product is filtered and washed with deionized water, dried and ground to obtain iodine-doped bulk carbon nitride.

[0037] Example 7

[0038] (1) 0.1 g of carbon nitride nanosheets and 1.26 g of cyanuric acid were added to a certain amount of 85 °C deionized water and mixed; (2) slowly adding the cyanuric acid solution obtained in step (1) dropwise to the carbon nitride dispersion, and then adding 1.9 g of ammonium iodide; (3) Transfer the mixed solution in step (2) to a 200 mL reactor and heat the reactor to 80 °C; (4) The reactor in step (3) is kept at 80°C for 8 h, the obtained product is filtered and washed with deionized water, dried and ground to obtain iodine-doped flaky carbon nitride.

[0039] Example 8

[0040] (1) 0.1 g of carbon nitride nanosheets and 1.26 g of cyanuric acid were added to a certain amount of 85 °C deionized water and mixed; (2) slowly adding the cyanuric acid solution obtained in step (1) dropwise to the carbon nitride dispersion, and then adding 1.9 g of ammonium iodide; (3) The mixed solution in step (2) was transferred to a 200 mL reactor and the temperature of the reactor was raised to 180 °C; (4) The reactor in step (3) was kept at 180°C for 6 h, the product was filtered and washed with deionized water, dried and ground to obtain iodine-doped carbon nitride microrods with a length of about 3 µm and a diameter of about 1 µm.

[0041] Example 9

[0042] (1) 0.1 g of carbon nitride nanosheets and 1.26 g of cyanuric acid were added to a certain amount of 85 °C deionized water and mixed; (2) slowly adding the cyanuric acid solution obtained in step (1) dropwise to the carbon nitride dispersion, and then adding 1.9 g of ammonium iodide; (3) The mixed solution in step (2) was transferred to a 200 mL reactor and the temperature of the reactor was raised to 180 °C; (4) The reactor in step (3) is kept at 180° C. for 10 h, the obtained product is filtered and washed with deionized water, dried and ground to obtain iodine-doped bulk carbon nitride.

[0043] The iodine-doped carbon nitride microrods of Examples 1-9 are used for the following photocatalytic hydrogen production reaction: A xenon lamp light source with a 420 nm filter, 40 mg of photocatalyst, 5 mL of triethanolamine, and 45 mL of deionized water were placed in the reactor.

[0044] Comparison of hydrogen production performance of iodine-doped carbon nitride obtained in Examples 1-9 Figure 4 shown.

[0045] The carbon nitride morphology obtained from the examples and Figure 4 From the comparison of hydrogen production performance, it can be seen that the photocatalytic performance of the iodine-doped carbon nitride microrods obtained in Example 1 and Example 8 is better than that of the block and sheet iodine-doped titanium nitride obtained in other examples, indicating that the mass ratio of carbon nitride in the carbon nitride dispersion to cyanuric acid in the cyanuric acid solution, the mass ratio of carbon nitride in the carbon nitride dispersion to iodine compounds, the hydrothermal reaction temperature, and the hydrothermal reaction time will have a significant effect on the morphology of carbon nitride.

[0046] Compared with the carbon nitride microrods obtained in Example 8, the carbon nitride microrods obtained in Example 1 are longer and have a larger diameter, and have higher selectivity and activity for hydrogen production photocatalysis.

[0047] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the technical principles of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A method for preparing iodine-doped carbon nitride microrods, characterized in that: The following steps are involved: S1: Preparation of carbon nitride nanosheets by step-by-step pyrolysis; S2: adding carbon nitride nanosheets and cyanuric acid into deionized water to obtain cyanuric acid solution and carbon nitride dispersion; S3: slowly dropping the cyanuric acid solution into the carbon nitride dispersion to obtain a mixed system, and then adding an iodine compound to the mixed system for a hydrothermal reaction; S4: The products of the hydrothermal reaction are separated into solid and liquid, and the solid is dried and ground to obtain iodine-doped carbon nitride microrods.

2. The method for preparing iodine-doped carbon nitride microrods according to claim 1, characterized in that: The mass ratio of the carbon nitride nanosheets in the carbon nitride dispersion to the cyanuric acid in the cyanuric acid solution is 1:(9-16.2).

3. The method for preparing iodine-doped carbon nitride microrods according to claim 1, characterized in that: The mass ratio of the carbon nitride nanosheets to the iodine compound in the carbon nitride dispersion is 1:(15-23).

4. The method for preparing iodine-doped carbon nitride microrods according to claim 1, characterized in that: The hydrothermal reaction temperature is 160-200° C., and the reaction time is 5-9 hours.

5. The method for preparing iodine-doped carbon nitride microrods according to claim 1, characterized in that: The iodine compound is ammonium iodide.

6. The method for preparing iodine-doped carbon nitride microrods according to claim 1, characterized in that: The thickness of the carbon nitride nanosheet in S1 is 10 to 300 nm.

7. The method for preparing iodine-doped carbon nitride microrods according to claim 1, characterized in that: The iodine-doped carbon nitride microrod has a length of 3 to 10 μm and a diameter of 2 to 3 μm.

8. An iodine-doped carbon nitride microrod, characterized in that: The iodine-doped carbon nitride microrods are prepared by the preparation method of any one of claims 1 to 7.

9. Use of the iodine-doped carbon nitride microrods according to claim 8 as a photocatalyst in a photocatalytic reaction.

Images