A method for regulating morphology of polymeric carbon nitride based on sodium chloride template

Abstract

This invention belongs to the field of materials preparation technology, specifically relating to a method for controlling the morphology of polymeric carbon nitride (Na-PHI) based on a sodium chloride template. It includes the following steps: determining the morphology of the desired polymeric carbon nitride; determining the ratio of sodium chloride to melamine according to the desired morphology; mixing sodium chloride and melamine according to the determined ratio to obtain a reaction precursor; calcining the reaction precursor in a reactor; obtaining the calcined product after calcination; washing the calcined product with deionized water to remove the sodium chloride template; and drying to obtain the synthesized polymeric carbon nitride. This invention achieves the controlled synthesis of polymeric carbon nitride with different morphologies by adjusting the mass ratio of sodium chloride and melamine in the precursor. Furthermore, the Na-PHI synthesized using this technology exhibits high crystallinity. Simultaneously, by simply increasing the proportion of raw materials proportionally, large-scale preparation of polymeric carbon nitride can be achieved.

Description

Technical Field

[0001] This invention belongs to the field of materials preparation technology, specifically relating to a method for controlling the morphology of polymerized carbon nitride based on sodium chloride template. Background Technology

[0002] Polymeric carbon nitride is mainly as follows Figure 1 The Na-containing Na-poly(heptazine imide) shown below is hereinafter referred to as Na-PHI. Currently, there are many methods for synthesizing polymeric carbon nitride, but they are mainly based on a random mixture of bulk and sheet-like forms, making it difficult to synthesize polymeric carbon nitride with uniform morphologies (bulk and sheet). The morphologies of polymeric carbon nitride synthesized in existing technologies are as follows: Figure 2 , 3 As shown. Therefore, there is an urgent need to provide a method for synthesizing polymeric carbon nitride with uniform morphologies (bulk, flake). Summary of the Invention

[0003] The purpose of this invention is to provide a method for controlling the morphology of polymerized carbon nitride based on sodium chloride template. By adjusting the mass ratio of sodium chloride and melamine in the precursor, polymerized carbon nitride with different morphologies can be synthesized in a controlled manner.

[0004] The objective of this invention is achieved through the following technical solution:

[0005] This invention provides a method for controlling the morphology of polymerized carbon nitride based on a sodium chloride template, comprising the following steps:

[0006] (1) Determine the morphology of the polymerized carbon nitride to be prepared, and determine the mass ratio of sodium chloride to melamine according to the morphology of the polymerized carbon nitride to be prepared;

[0007] (2) Sodium chloride and melamine are mixed evenly according to the proportion determined in step (1) to obtain the reaction precursor;

[0008] (3) The reaction precursor is calcined in a reactor. After calcination, the calcined product is obtained. The calcined product is washed with deionized water to remove the sodium chloride template and dried to obtain the synthesized polycarbon nitride.

[0009] In step (1), the morphology of the polymerized carbon nitride changes from a pure block shape to a sheet shape as the ratio of sodium chloride to melamine increases.

[0010] Furthermore, in step (1), when the mass ratio of sodium chloride to melamine reaches 80:1 or higher, the polynitride exists only in flake form; when the mass ratio of sodium chloride to melamine is less than 5:1, the polynitride exists only in block form.

[0011] Furthermore, in step (2), the mixing also includes ball milling the mixed sodium chloride with melamine.

[0012] Furthermore, in step (3), the reactor includes a box furnace or a tube furnace.

[0013] Furthermore, in step (3), the calcination involves placing the reaction precursor into the reactor and heating it to 600-650°C at a heating rate of 4-6°C / min and holding it at that temperature for 2 hours.

[0014] Furthermore, in step (3), the entire calcination process is carried out in an atmosphere of argon or nitrogen gas.

[0015] The present invention also provides a method for preparing polycarbon nitride using the method described above for controlling the morphology of polycarbon nitride based on sodium chloride template.

[0016] Furthermore, the polymerized carbon nitride includes block form, flake form, and a mixture of block and flake forms.

[0017] The beneficial effects of this invention are as follows:

[0018] This invention allows for the control of the morphology of synthesized polycarbon nitride (PCN), obtaining highly crystalline PCN with specific flake / block ratios, pure block form, and pure flake form. Simultaneously, this method uses ball milling to homogenize the precursor, ensuring its uniformity and guaranteeing the consistency of subsequent products. By adjusting the mass ratio of sodium chloride and melamine in the precursor, this technology enables the controlled synthesis of Na-PHI with different morphologies, while the synthesized Na-PHI exhibits high crystallinity. Furthermore, by simply scaling up the raw material ratio, large-scale preparation of Na-PHI can be achieved. Attached Figure Description

[0019] Figure 1 This is a molecular structure diagram of polymerized carbon nitride, where blue atoms represent N, gray atoms represent C, and cyan atoms represent Na.

[0020] Figure 2 Polymeric carbon nitride synthesized using existing technologies at a 20nm scale;

[0021] Figure 3 Polymeric carbon nitride synthesized in the prior art at a 10μm scale;

[0022] Figure 4 Polymerized carbon nitride prepared in Example 1 at a 100 μm scale;

[0023] Figure 5 Polymeric carbon nitride prepared in Example 1 at a 10 μm scale;

[0024] Figure 6 The polymerized carbon nitride prepared in Example 2 is measured on a 500 μm scale.

[0025] Figure 7 Polymeric carbon nitride prepared in Example 2 at a 10 μm scale;

[0026] Figure 8 Polymerized carbon nitride prepared in Example 3 at a 100 μm scale;

[0027] Figure 9 Polymeric carbon nitride prepared in Example 3 at a 30 μm scale;

[0028] Figure 10 Polymeric carbon nitride prepared in Example 4 at a 100 μm scale;

[0029] Figure 11 Polymerized carbon nitride prepared in Example 4 at a 30 μm scale;

[0030] Figure 12 Polymerized carbon nitride prepared in Example 5 at a 10 μm scale;

[0031] Figure 13 Polymerized carbon nitride prepared in Example 5 at a 50 μm scale;

[0032] Figure 14 The X-ray diffraction (XRD) patterns of the polymeric carbon nitride synthesized in Examples 1-5 are shown below.

[0033] Figure 15 The image shows high-resolution transmission electron microscopy (HR-TEM) images of the polymeric carbon nitride synthesized in Examples 1-5, where d is the interplanar spacing and (100) refers to the 100 crystal plane. Detailed Implementation

[0034] The general synthesis process of this invention is as follows: melamine and commercially available sodium chloride are mixed in a certain proportion and then ball-milled to obtain a homogeneous mixture, yielding a precursor. The precursor is then heated to 625°C (600-650°C, preferably 625°C) at a heating rate of 5°C / min (4-6°C, preferably 5°C) in a box furnace / tube furnace (preferably a tube furnace), and held at 625°C for 2 hours. The entire process is carried out in an atmosphere of argon (argon or nitrogen, preferably argon). The calcined product is then washed with deionized water to remove the sodium chloride template, and dried to obtain the synthesized polymeric carbon nitride, denoted as Na-PHI.

[0035] In this process, melamine in the raw materials plays a role in forming polycarbon nitride, and sodium chloride controls the morphology of the polycarbon nitride through the extrusion of sodium chloride crystals; therefore, sodium chloride is called a template. Washing away the sodium chloride template involves the following steps: after calcination, melamine is transformed into polycarbon nitride, and sodium chloride has already acted as a template. To obtain pure polycarbon nitride, the excellent solubility of sodium chloride in water is utilized to remove it through washing.

[0036] The technical solutions of this invention will be clearly and completely described below with reference to the embodiments thereof. Obviously, the described embodiments are only a part of the embodiments of this invention, and not all of them. All other embodiments obtained by those skilled in the art based on the embodiments of this invention without creative effort are within the scope of protection of this invention.

[0037] Example 1

[0038] Melamine and commercially available sodium chloride were mixed at a mass ratio of sodium chloride:melamine = 5:1, and then ball-milled to obtain a homogeneous mixture, yielding a precursor. The precursor was then placed in a tube furnace and heated to 625°C at a rate of 5°C / min, and held at 625°C for 2 hours to obtain the calcined product. The entire process was carried out in an argon atmosphere. The calcined product was then washed with deionized water to remove the sodium chloride template, and dried to obtain the synthesized polycarbon nitride, denoted as Na-PHI. The SEM image of the obtained Na-PHI is shown below. Figure 4 , 5 As shown.

[0039] Example 2

[0040] Compared with Example 1, the only difference is that the mass ratio of sodium chloride to melamine is 10:1. The final SEM image of Na-PHI is as follows. Figure 6 , 7 As shown.

[0041] Example 3

[0042] Compared to Example 1, the only difference is that the mass ratio of sodium chloride to melamine is 20:1. The final SEM image of Na-PHI is as follows. Figure 8 , 9 As shown.

[0043] Example 4

[0044] Compared with Example 1, the only difference is that the mass ratio of sodium chloride to melamine is 40:1. The final SEM image of Na-PHI is as follows. Figure 10 , 11 As shown.

[0045] Example 5

[0046] Compared with Example 1, the only difference is that the mass ratio of sodium chloride to melamine is 80:1. The final SEM image of Na-PHI is as follows. Figure 12 , 13 As shown.

[0047] Among them, the X-ray diffraction (XRD) patterns of various scales corresponding to the above embodiments of the present invention are as follows: Figure 14 As shown, the high-resolution transmission electron microscope (HR-TEM) image is as follows. Figure 15 As shown.

[0048] Depend on Figure 4 , 5 It is known that, using the method of the present invention, when the mass ratio of sodium chloride to melamine is 5:1, the Na-PHI produced is all in block form, and the surface of each block is basically composed of granular Na-PHI.

[0049] Depend on Figure 6 , 7 It is known that, using the method of the present invention, when the mass ratio of sodium chloride to melamine is 10:1, the resulting Na-PHI begins to show flaky Na-PHI, but the vast majority is still blocky Na-PHI.

[0050] Depend on Figure 8 , 9 It is known that, using the method of the present invention, when the mass ratio of sodium chloride to melamine is 20:1, the resulting Na-PHI contains a mixture of block Na-PHI and flake Na-PHI, with a ratio of approximately 1:1.

[0051] Depend on Figure 10 , 11 It is known that, using the method of the present invention, when the mass ratio of sodium chloride to melamine is 40:1, the resulting Na-PHI contains a mixture of block Na-PHI and flake Na-PHI, but the vast majority of the flake Na-PHI exists in the form of flake Na-PHI.

[0052] Depend on Figure 12 , 13 It can be seen that, using the method of the present invention, when the mass ratio of sodium chloride to melamine is 80:1, the obtained Na-PHI basically only contains flake-shaped Na-PHI and basically does not contain block-shaped Na-PHI.

[0053] In summary, as the ratio of sodium chloride to melamine increases, the morphology of Na-PHI changes from purely lumpy to a mixture of lumpy and flake-like forms (and, the higher the ratio, the greater the proportion of flake-like Na-PHI, showing a positive correlation). When the ratio reaches 80:1 or higher, Na-PHI exists only in flake form. Meanwhile, due to... Figure 14 It can be seen that the diffraction peaks of Na-PHI synthesized using this method at various ratios are quite sharp, proving that these samples all have high crystallinity. Meanwhile, through observation... Figure 15 The stripes of Na-PHI can be clearly seen in the picture, which also indicates that it has a high degree of crystallinity.

[0054] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit it. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the spirit and scope of the technical solutions of the present invention, and all such modifications or substitutions should be covered within the scope of the claims of the present invention.

Claims

1. A method for regulating morphology of polymeric carbon nitride based on sodium chloride template, characterized in that, The method comprises the following steps: (1) determining the morphology of the polymeric carbon nitride to be prepared, and determining the mass ratio of sodium chloride to melamine according to the morphology of the polymeric carbon nitride to be prepared; (2) uniformly mixing sodium chloride and melamine in the ratio determined in step (1) to obtain a reaction precursor; (3) calcining the reaction precursor in a reaction furnace, and obtaining a calcined product after calcination, and washing the calcined product with deionized water to remove sodium chloride templates, and drying to obtain the synthesized polymeric carbon nitride; In step (1), the morphology of the polymeric carbon nitride changes from pure block to sheet as the ratio of sodium chloride to melamine increases; In step (1), when the mass ratio of sodium chloride to melamine is 80:1 or more, the polymeric carbon nitride exists only in the form of sheet; and when the mass ratio of sodium chloride to melamine is less than 5:1, the polymeric carbon nitride exists only in the form of block; In step (2), the mixing further comprises ball milling the mixed sodium chloride and melamine; In step (3), the reaction furnace comprises a box furnace or a tube furnace; In step (3), the calcination is to heat the reaction precursor to 600-650℃ at a heating rate of 4-6℃ / min and keep for 2h after the reaction precursor is put into the reaction furnace.

2. The method according to claim 1, wherein, In step (3), the entire process is carried out in an atmosphere of argon or nitrogen gas flow.

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