CN115608401A

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Info

Publication number: CN115608401A
Application number: CN202211287069.8A
Authority: CN
Inventors: 朱俊武; 邓景耀; 孙敬文; 付永胜; 熊攀; 张文耀; 薛亮; 代黎明
Original assignee: Nanjing University of Science and Technology
Current assignee: Nanjing University of Science and Technology
Priority date: 2022-10-20
Filing date: 2022-10-20
Publication date: 2023-01-17

Abstract

Translated fromChinese

本发明公开一种基于三聚氰酸‑氯化锂共晶的高结晶性氮化碳及其制备方法。所述方法是将三聚氰酸与氯化锂通过球磨法制得含有三聚氰酸‑氯化锂共晶的前驱体，然后通过高温煅烧，水洗、过滤、烘干等处理合成氮化碳光催化剂。本发明制备方法简单，制得的氮化碳具有良好的可见光响应和光催化产氢性能，适用于半导体光催化产氢领域。

The invention discloses a highly crystalline carbon nitride based on cyanuric acid-lithium chloride eutectic and a preparation method thereof. The method is to use cyanuric acid and lithium chloride to prepare a precursor containing cyanuric acid-lithium chloride eutectic through ball milling, and then calcine at high temperature, wash with water, filter, dry, etc. to process and synthesize carbon nitride. catalyst. The preparation method of the invention is simple, and the prepared carbon nitride has good visible light response and photocatalytic hydrogen production performance, and is suitable for the field of semiconductor photocatalytic hydrogen production.

Description

Translated fromChinese

一种基于三聚氰酸-氯化锂共晶的高结晶性氮化碳及其制备方法A kind of highly crystalline carbon nitride based on cyanuric acid-lithium chloride eutectic and its preparationmethod

技术领域technical field

本发明涉及一种基于三聚氰酸-氯化锂共晶的高结晶性氮化碳及其制备方法，属于半导体光催化产氢技术领域。The invention relates to a highly crystalline carbon nitride based on cyanuric acid-lithium chloride eutectic and a preparation method thereof, belonging to the technical field of semiconductor photocatalytic hydrogen production.

背景技术Background technique

在化石燃料枯竭的今天，能源短缺已经逐渐成为了我国亟需解决的难题。氢能作为一种高效的清洁能源，被视作是替代化石燃料的最优解。与此同时太阳能作为一种取之不尽、用之不竭的清洁能源，同样受到了很多关注。而光催化产氢技术正好可以实现从太阳能到氢能的转化，因此它的发展在近年来受到了很多研究者的关注。现今光催化技术面临的最大挑战是需要找到一种高效、稳定、廉价，且环境友好的光催化剂。Today, when fossil fuels are exhausted, energy shortage has gradually become a problem that our country needs to solve urgently. As an efficient and clean energy, hydrogen energy is regarded as the optimal solution to replace fossil fuels. At the same time, as an inexhaustible clean energy, solar energy has also received a lot of attention. The photocatalytic hydrogen production technology can just realize the conversion from solar energy to hydrogen energy, so its development has attracted the attention of many researchers in recent years. The biggest challenge facing photocatalytic technology today is to find an efficient, stable, cheap and environmentally friendly photocatalyst.

氮化碳是一种有机半导体，其具有成本低、无毒、适中的禁带宽度（2.7 eV）和出色的可见光响应等特点。自2009年首次被运用到光催化产氢领域之后，氮化碳迅速成为了光催化领域的热点材料。传统的氮化碳制备方法主要是通过直接高温煅烧含氮单体获得，但这种高温缩聚反应会产生例如氨气等气体，导致反应平衡向逆性进行，无法做到反应完全。这种条件下制备的块状氮化碳（PCN）存在结晶性差（半晶态）、比表面积低、缺陷多、光生电荷分离效率差等问题，从而导致PCN的光催化性能较差。相较于PCN，结晶性氮化碳（CCN）具有更加完整的三嗪环、庚嗪环面内结构，这使得CCN相较于传统的PCN有更优的电子传输能力，是更具潜力的光催化材料。除此之外，三嗪环和庚嗪环这两种结构单元构成的CCN分别被称作聚三嗪环酰亚胺（PTI）和聚庚嗪环酰亚胺（PHI）。其中PHI相较于PTI具有更强的电子离域能力以及更适宜光催化产氢的能带结构和位置，这些特点使得PHI成为更理想的光催化产氢催化剂。现在CCN主要是通过熔融盐法、微波辅助法来制备。其中熔融盐法制备CCN主要是通过将含氮单体与熔融盐进行手动研磨后再高温煅烧获来实现的。由于熔融盐法中需要用到大量具有吸水性的碱金属盐（例如，LiCl、CsCl等），这导致了前驱体在前期手动研磨时的处理不便。文献1（Adv. Mater. 2021, 33, 2101466）。除此之外手动研磨也存在很大的不稳定性，导致实验结果时常不具有可重复性。且传统含氮单体（例如，二氰二胺，三聚氰胺等）所制备的CCN存在比表面积小，活性位点少等问题，这使得由传统含氮单体制备的CCN无法拥有特别理想的光催化性能。Carbon nitride is an organic semiconductor with low cost, non-toxicity, moderate bandgap (2.7 eV), and excellent visible light response. Since it was first applied to the field of photocatalytic hydrogen production in 2009, carbon nitride has quickly become a hot material in the field of photocatalysis. The traditional carbon nitride preparation method is mainly obtained by direct high-temperature calcination of nitrogen-containing monomers, but this high-temperature polycondensation reaction will generate gases such as ammonia, which will cause the reaction equilibrium to proceed inversely, and the reaction cannot be completed. Bulk carbon nitride (PCN) prepared under this condition has problems such as poor crystallinity (semi-crystalline state), low specific surface area, many defects, and poor separation efficiency of photogenerated charges, which lead to poor photocatalytic performance of PCN. Compared with PCN, crystalline carbon nitride (CCN) has a more complete in-plane structure of triazine ring and heptazine ring, which makes CCN have better electron transport ability than traditional PCN, and is more potential photocatalytic material. In addition, the CCN composed of the two structural units of triazine ring and heptazine ring is called polytriazine cyclic imide (PTI) and polyheptazine cyclic imide (PHI), respectively. Among them, compared with PTI, PHI has stronger electron delocalization ability and more suitable energy band structure and position for photocatalytic hydrogen production. These characteristics make PHI a more ideal photocatalytic hydrogen production catalyst. At present, CCN is mainly prepared by molten salt method and microwave-assisted method. Among them, the preparation of CCN by the molten salt method is mainly achieved by manually grinding nitrogen-containing monomers with molten salt and then calcining at high temperature. Because the molten salt method needs to use a large amount of alkali metal salts (for example, LiCl, CsCl, etc.) Literature 1 (Adv. Mater. 2021, 33, 2101466). In addition, manual grinding also has great instability, resulting in experimental results that are often not reproducible. Moreover, CCN prepared from traditional nitrogen-containing monomers (for example, dicyandiamine, melamine, etc.) has problems such as small specific surface area and few active sites, which makes it impossible for CCN prepared from traditional nitrogen-containing monomers to have particularly ideal optical properties. catalytic performance.

发明内容Contents of the invention

本发明的目的是提供一种基于三聚氰酸-氯化锂共晶的高结晶性氮化碳及其制备方法。The object of the present invention is to provide a kind of highly crystalline carbon nitride based on cyanuric acid-lithium chloride eutectic and preparation method thereof.

实现本发明目的的技术解决方案为：The technical solution that realizes the object of the present invention is:

一种基于三聚氰酸-氯化锂共晶的高结晶性氮化碳及其制备方法，包括以下步骤：A kind of highly crystalline carbon nitride based on cyanuric acid-lithium chloride eutectic and preparation method thereof, comprising the following steps:

步骤一，球磨法合成前驱体LiCAStep 1: Synthesize the precursor LiCA by ball milling

按摩尔比1:1，将三聚氰酸与氯化锂置于球磨罐中，滴加少量甲醇，以一定频率球磨一定时间后得到含有三聚氰酸-氯化锂共晶（CA-LiCl cocrystal）的前驱体LiCA，并干燥；Put cyanuric acid and lithium chloride in a ball mill tank at a molar ratio of 1:1, add a small amount of methanol dropwise, and ball mill at a certain frequency for a certain period of time to obtain a cyanuric acid-lithium chloride eutectic (CA-LiCl cocrystal) precursor LiCA, and dried;

步骤二，高温煅烧制备高结晶性氮化碳（CCN）Step 2: High-temperature calcination to prepare highly crystalline carbon nitride (CCN)

将步骤一所得前驱体LiCA置于管式炉中，在氩气气氛下高温煅烧后，水洗、过滤、干燥即可得到高结晶性氮化碳。The precursor LiCA obtained instep 1 is placed in a tube furnace, calcined at a high temperature under an argon atmosphere, washed with water, filtered, and dried to obtain highly crystalline carbon nitride.

优选地，步骤1中，球磨的频率为5-25 Hz，时间为0.5-2 h。Preferably, instep 1, the frequency of ball milling is 5-25 Hz, and the time is 0.5-2 h.

优选地，步骤1中，以0.01mol三聚氰酸为计量标准，甲醇滴加量为0.5-2 ml，前驱体的干燥温度为60-80 °C，时间为1-2 h。Preferably, instep 1, with 0.01mol cyanuric acid as the measurement standard, the amount of methanol added dropwise is 0.5-2 ml, the drying temperature of the precursor is 60-80 ° C, and the time is 1-2 h.

优选地，步骤2中，于550°C下高温煅烧4 h。Preferably, instep 2, high-temperature calcination at 550° C. for 4 h.

优选地, 步骤2中，过滤方式采用抽滤，产物干燥温度为60-80 °C，时间为8-24 h。Preferably, instep 2, the filtration method adopts suction filtration, the product drying temperature is 60-80 ° C, and the time is 8-24 h.

本发明与现有技术相比，其优势在于：Compared with the prior art, the present invention has the advantages of:

（1）本发明以基于三聚氰酸-氯化锂共晶（CA-LiCl cocrystal）的前驱体来制备高结晶性氮化碳（CCN），利用该共晶防潮的特性可以克服在熔融盐法操作过程中氯化锂吸水导致的不便。且形成共晶的过程中利用到的球磨法相较于熔融盐法中的手动研磨更稳定，大大提高了实验的可重复性。(1) The present invention uses a precursor based on cyanuric acid-lithium chloride cocrystal (CA-LiCl cocrystal) to prepare highly crystalline carbon nitride (CCN), and the moisture-proof properties of the eutectic can overcome the problem in molten salt Inconvenience caused by lithium chloride water absorption during the operation of the method. Moreover, the ball milling method used in the process of forming a co-crystal is more stable than the manual grinding in the molten salt method, which greatly improves the repeatability of the experiment.

（2）本发明制备的CCN相较于基于传统含氮单体所制备的CCN，由于其前驱体中所含有的三聚氰酸在高温下会分解为异氰酸（HCNO），使其具有高比表面积和多孔的特性；且在聚合过程中异氰酸是聚合的最小单元，更易形成氰基（-CN）这种催化活性位点，这使得其具有更加优越的光催化产氢性能。(2) Compared with the CCN prepared based on traditional nitrogen-containing monomers, the CCN prepared by the present invention has the properties of High specific surface area and porous characteristics; and isocyanic acid is the smallest unit of polymerization during the polymerization process, and it is easier to form the catalytic active site of cyano group (-CN), which makes it have more superior photocatalytic hydrogen production performance.

（3）本发明制备出的材料为褶皱状，特殊的形貌可以在催化过程中暴露更多的活性位点，提高光催化产氢的效率；(3) The material prepared by the present invention is wrinkled, and the special shape can expose more active sites in the catalytic process, improving the efficiency of photocatalytic hydrogen production;

（4）本发明最终的材料为聚庚嗪环酰亚胺（PHI）型的高结晶性氮化碳（CCN），更加完整的庚嗪环面内晶体结构使得氮化碳具有更多的离域电子，优化了其电子结构和光生电荷分离效率，进一步提高了催化活性。相较于传统的块状氮化碳，更具有发展潜力。(4) The final material of the present invention is highly crystalline carbon nitride (CCN) of the polyheptazine ring imide (PHI) type, and the more complete crystal structure in the heptazine ring makes carbon nitride have more ion Domain electrons, optimized its electronic structure and photogenerated charge separation efficiency, further enhanced the catalytic activity. Compared with the traditional block carbon nitride, it has more development potential.

附图说明Description of drawings

图1 为本发明的一种基于三聚氰酸-氯化锂共晶的高结晶性氮化碳的制备流程示意图。Figure 1 is a schematic diagram of the preparation process of a highly crystalline carbon nitride based on cyanuric acid-lithium chloride eutectic of the present invention.

图2 为实施例1中前驱体LiCA-rate₀的XRD谱图。Figure 2 is the XRD spectrum of the precursor LiCA-rate₀ in Example 1.

图3 为实施例1中CCN-T₀样品的 (a) XRD图 (b) FTIR图。Figure 3 is (a) XRD pattern (b) FTIR pattern of the CCN-T₀ sample in Example 1.

图4为实施例1中CCN-T₀的 (a) SEM图 (b) 氮气吸脱附曲线图。Fig. 4 is (a) SEM image (b) nitrogen adsorption-desorption curve diagram of CCN-T₀ in Example 1.

图5为实施例1中CCN-T₀样品的 (a) 光催化产氢性能图 (b) 固体紫外DRS谱图。Figure 5 is the (a) photocatalytic hydrogen production performance diagram (b) solid ultraviolet DRS spectrum diagram of the CCN-T₀ sample in Example 1.

图6为对比例1中CCN-T₁样品的 (a) XRD图 (b) FTIR图。Figure 6 is (a) XRD pattern (b) FTIR pattern of CCN-T₁ sample in Comparative Example 1.

图7为对比例1中CCN-T₁样品的 (a) 光催化产氢性能图 (b) 固体紫外DRS谱图。Figure 7 is the (a) photocatalytic hydrogen production performance diagram (b) solid ultraviolet DRS spectrum of the CCN-T₁ sample in Comparative Example 1.

图8为对比例2中CCN-T₂样品的 (a) XRD图 (b) FTIR图。Figure 8 is the (a) XRD pattern (b) FTIR pattern of the CCN-T₂ sample in Comparative Example 2.

图9为对比例2中CCN-T₂样品的 (a) 光催化产氢性能图 (b) 固体紫外DRS谱图。Figure 9 is the (a) photocatalytic hydrogen production performance diagram (b) solid ultraviolet DRS spectrum of the CCN-T₂ sample in Comparative Example 2.

图10为对比例3中前驱体LiCA-rate₁的XRD图。FIG. 10 is the XRD pattern of the precursor LiCA-rate₁ in Comparative Example 3.

图11为对比例3中CCN-rate₁样品的 (a) XRD图 (b) FTIR图。Figure 11 is the (a) XRD pattern (b) FTIR pattern of the CCN-rate₁ sample in Comparative Example 3.

图12为对比例3中CCN-rate₁样品的 (a) 光催化产氢性能图 (b) 固体紫外DRS谱图。Figure 12 is the (a) photocatalytic hydrogen production performance diagram (b) solid ultraviolet DRS spectrum of the CCN-rate₁ sample in Comparative Example 3.

图13为对比例4中前驱体LiCA-rate₂的XRD图。FIG. 13 is the XRD pattern of the precursor LiCA-rate₂ in Comparative Example 4.

图14为对比例4中CCN-rate₂样品的 (a) XRD图 (b) FTIR图。Figure 14 is the (a) XRD pattern (b) FTIR pattern of the CCN-rate₂ sample in Comparative Example 4.

图15为对比例4中CCN-rate₂样品的 (a) 光催化产氢性能图 (b) 固体紫外DRS谱图Figure 15 is the (a) photocatalytic hydrogen production performance diagram (b) solid ultraviolet DRS spectrum of the CCN-rate₂ sample in Comparative Example 4

图16为对比例5中 CCN-mel样品的 (a) XRD图 (b) FTIR图。Figure 16 is the (a) XRD pattern (b) FTIR pattern of the CCN-mel sample in Comparative Example 5.

图17为对比例5中CCN-mel样品的 (a) SEM图 (b) 氮气吸脱附曲线图。Figure 17 is (a) SEM image (b) nitrogen adsorption-desorption curve of the CCN-mel sample in Comparative Example 5.

图18为对比例5中CCN-mel样品的 (a) 光催化产氢性能图 (b) 固体紫外DRS谱图。Figure 18 is the (a) photocatalytic hydrogen production performance diagram (b) solid ultraviolet DRS spectrum of the CCN-mel sample in Comparative Example 5.

图19为对比例5中 CCN-DICY样品的 (a) XRD图 (b) FTIR图。Figure 19 is the (a) XRD pattern (b) FTIR pattern of the CCN-DICY sample in Comparative Example 5.

图20为对比例5中CCN-DICY样品的 (a) SEM图 (b) 氮气吸脱附曲线图。Figure 20 is (a) SEM image (b) nitrogen adsorption-desorption curve of the CCN-DICY sample in Comparative Example 5.

图21为对比例5中CCN-DICY样品的 (a) 光催化产氢性能图 (b) 固体紫外DRS谱图。Figure 21 is the (a) photocatalytic hydrogen production performance diagram (b) solid ultraviolet DRS spectrum of the CCN-DICY sample in Comparative Example 5.

图22为对比例7-10中 CCN-T₃，CNN-T₄，CCN-T₅，CCN-T₆样品的XRD图。Fig. 22 is the XRD patterns of CCN-T₃ , CNN-T₄ , CCN-T₅ , and CCN-T₆ samples in Comparative Examples 7-10.

具体实施方式detailed description

下面通过具体实施例和附图对本发明做进一步说明。The present invention will be further described below through specific embodiments and accompanying drawings.

三聚氰酸作为一种在高温下易升华、分解的含氮单体，在常压下无法通过缩聚反应制备得到氮化碳。但得益于其易升华、分解的性质，在非晶态的氮化碳的前驱体设计中三聚氰酸常扮演“造孔剂”的角色（例如三聚氰胺-三聚氰酸超分子）。在本发明中，我们利用三聚氰酸-氯化锂共晶作为前驱体首次实现了三聚氰酸到氮化碳的合成，且所制备的氮化碳不仅具有PHI的晶体结构，同时还具备高比表面积、多孔的特点。As a nitrogen-containing monomer that is easy to sublimate and decompose at high temperature, cyanuric acid cannot be prepared by polycondensation reaction to obtain carbon nitride under normal pressure. However, due to its easy sublimation and decomposition properties, cyanuric acid often plays the role of "pore-forming agent" in the design of amorphous carbon nitride precursors (such as melamine-cyanuric acid supramolecules). In the present invention, we have realized the synthesis of cyanuric acid to carbon nitride for the first time by using cyanuric acid-lithium chloride eutectic as a precursor, and the prepared carbon nitride not only has the crystal structure of PHI, but also It has the characteristics of high specific surface area and porosity.

实施例1Example 1

结合图1，本实施例给出了本发明所述的高结晶性氮化碳的制备流程示意图。In conjunction with FIG. 1 , this embodiment provides a schematic flow chart of the preparation of the highly crystalline carbon nitride of the present invention.

步骤一：称取1.29 g（0.01 mol）三聚氰酸和0.434 g（0.01 mol）的氯化锂（摩尔比1：1）置于球磨罐中并混合，之后滴加1 mL的甲醇于球磨罐中。以25 Hz的频率球磨2 h后，将白色产物在60℃下烘干，所得白色粉末即为前驱体LiCA- rate₀。图2为LiCA- rate₀的XRD谱图，结果表明前驱体LiCA-rate₀的XRD衍射花样与三聚氰酸-氯化锂共晶（CA-LiClcocrystal）一致。Step 1: Weigh 1.29 g (0.01 mol) of cyanuric acid and 0.434 g (0.01 mol) of lithium chloride (molar ratio 1:1) into a ball mill jar and mix them, then add 1 mL of methanol dropwise to the ball mill in the can. After ball milling at a frequency of 25 Hz for 2 h, the white product was dried at 60 °C, and the white powder obtained was the precursor LiCA-rate₀ . Figure 2 is the XRD spectrum of LiCA-rate_0. The results show that the XRD diffraction pattern of the precursor LiCA-rate₀ is consistent with cyanuric acid-lithium chloride eutectic (CA-LiClcocrystal).

步骤二：称取1 g LiCA- rate₀置于瓷舟之中，在氩气气氛下在管式炉中高温煅烧，以2.3 °C/min的升温速率升至550 °C并保温4 h，冷却至室温后得到棕色产物，将其水洗后过滤，最终得到结晶性氮化碳。所得产物命名为CCN-T₀。图3为CCN-T₀的(a) XRD图，(b)FTIR图，XRD结果表明CCN-T₀具有良好的结晶性和明显的PHI晶体结构，FTIR结果表明CCN具有氮化碳的特征官能团和光催化活性官能团氰基（-CN）。图4为CCN-T₀的 (a) SEM图，(b)氮气吸脱附曲线图，从SEM图中可以看到CCN-T₀具有褶皱状的形貌，从氮气吸脱附等温线图中可以发现CCN-T₀相较于PCN具有更大的比表面积，BET比表面积达到了155.41 m²g^-1，更有利于光催化活性位点的暴露。Step 2: Weigh 1 g of LiCA-rate₀ and place it in a porcelain boat, calcinate at high temperature in a tube furnace under an argon atmosphere, raise the temperature to 550 °C at a rate of 2.3 °C/min and keep it for 4 h, After cooling to room temperature, a brown product was obtained, which was washed with water and filtered to obtain crystalline carbon nitride. The resulting product was named CCN-T₀ . Figure 3 is the (a) XRD pattern and (b) FTIR pattern of CCN-T_0. The XRD results show that CCN-T₀ has good crystallinity and obvious PHI crystal structure. The FTIR results show that CCN has the characteristic functional groups of carbon nitride and the photocatalytically active functional group cyano (-CN). Figure 4 is (a) SEM image of CCN-T₀ , (b) nitrogen adsorption-desorption curve, from the SEM image it can be seen that CCN-T₀ has a wrinkled morphology, from the nitrogen adsorption-desorption isotherm It can be found that CCN-T₀ has a larger specific surface area than PCN, and the BET specific surface area reaches 155.41 m² g^-1 , which is more conducive to the exposure of photocatalytic active sites.

光催化产氢活性试验：Photocatalytic hydrogen production activity test:

称取20 mg CCN-T₀超声分散到由90 mL的去离子水和10 mL的三乙醇胺组成的混合溶液中。随后在分散液中加入20 uL的氯铂酸，使得催化剂表面负载上3 wt%的Pt助催化剂。之后将悬浮液倒入光催化的石英反应器中，盖上石英光窗。将反应器与光催化分解水评价系统相连接，完成一系列抽真空的操作后即可启动反应。本实验采用了300 W的氙灯作为光源，并配420 nm滤光片。测试中的进样过程可由装置自动完成，而所收集的氢气可由气相色谱在线评价。图5为CCN-T₀的 (a) 光催化产氢性能图，以及 (b) 固体紫外DRS图。可以看到CCN-T₀的产氢性能远优于块状氮化碳（PCN），产氢效率达到了3187 µmol/g/h，说明CCN-T₀具有良好的光催化产氢性能，且CCN-T₀在可见光波段（420 nm以下）也具有光响应。Weigh 20 mg of CCN-T₀ and ultrasonically disperse it into a mixed solution consisting of 90 mL of deionized water and 10 mL of triethanolamine. Then 20 uL of chloroplatinic acid was added to the dispersion, so that 3 wt% Pt cocatalyst was supported on the surface of the catalyst. The suspension is then poured into a photocatalytic quartz reactor and covered with a quartz light window. Connect the reactor with the photocatalytic water splitting evaluation system, and start the reaction after completing a series of vacuuming operations. In this experiment, a 300 W xenon lamp was used as the light source and equipped with a 420 nm filter. The sampling process in the test can be automatically completed by the device, and the collected hydrogen can be evaluated online by gas chromatography. Figure 5 shows (a) the photocatalytic hydrogen production performance diagram and (b) the solid ultraviolet DRS diagram of CCN-T₀ . It can be seen that the hydrogen production performance of CCN-T₀ is much better than that of bulk carbon nitride (PCN), and the hydrogen production efficiency reaches 3187 μmol/g/h, indicating that CCN-T₀ has good photocatalytic hydrogen production performance, and CCN-T₀ also has photoresponse in the visible light band (below 420 nm).

对比例1Comparative example 1

参照实施例1中的步骤进行反应，唯一不同的是改变煅烧温度，以2.3^oC/min的升温速率升至600 °C并保温4 h，冷却至室温后得到棕色产物，将其水洗后过滤，所得产物命名为CCN-T₁。图6为此条件下前驱体的 (a) XRD图和 (b) FTIR图, 结果表明CCN-T₁同样具有良好的结晶性和氮化碳特征官能团，但晶体结构更加偏向PTI的结构。图7为CCN-T₁的(a) 光催化产氢性能图，以及 (b) 固体紫外DRS图。可以看到CCN-T₁具有可见光波段（420nm以下）的光吸收，且产氢性能优于块状氮化碳（PCN），但低于CCN-T₀的产氢性能，产氢效率达到了1374 µmol/g/h。。React with reference to the steps in Example 1, the only difference is to change the calcination temperature, rise to 600 ° C with a heating rate of 2.3^o C/min and keep it warm for 4 h, after cooling to room temperature, a brown product is obtained, which is washed with water and filtered , and the resulting product was named CCN-T₁ . Figure 6 shows (a) XRD pattern and (b) FTIR pattern of the precursor under this condition. The results show that CCN-T₁ also has good crystallinity and carbon nitride characteristic functional groups, but the crystal structure is more biased towards the structure of PTI. Figure 7 shows (a) the photocatalytic hydrogen production performance diagram and (b) the solid ultraviolet DRS diagram of CCN-T₁ . It can be seen that CCN-T₁ has light absorption in the visible light band (below 420nm), and its hydrogen production performance is better than that of bulk carbon nitride (PCN), but lower than that of CCN-T₀ , and its hydrogen production efficiency has reached 1374 µmol/g/h. .

对比例2Comparative example 2

参照实施例1中的步骤进行反应，唯一不同的是改变煅烧温度，以2.3^oC/min的升温速率升至600 °C并保温4 h，冷却至室温后得到棕色产物，将其水洗后过滤，所得产物命名为CCN-T₂。图8为此条件下产物的 (a) XRD和 (b) FTIR, 结果表明CCN-T₂同样具有良好的结晶性和氮化碳特征官能团，但晶体结构更加偏向PTI的结构。图9为CCN-T₂的(a) 光催化产氢性能图，以及(b) 固体紫外DRS图。可以看到CCN-T₂具有可见光波段（420 nm以下）的光吸收，且产氢性能优于块状氮化碳（PCN），但低于CCN-T₀的产氢性能，产氢效率达到了687µmol/g/h。React with reference to the steps in Example 1, the only difference is to change the calcination temperature, rise to 600 ° C with a heating rate of 2.3^o C/min and keep it warm for 4 h, after cooling to room temperature, a brown product is obtained, which is washed with water and filtered , and the resulting product was named CCN-T₂ . Figure 8 shows (a) XRD and (b) FTIR of the product under this condition. The results show that CCN-T₂ also has good crystallinity and carbon nitride characteristic functional groups, but the crystal structure is more biased towards the structure of PTI. Figure 9 is the (a) photocatalytic hydrogen production performance diagram and (b) solid ultraviolet DRS diagram of CCN-T₂ . It can be seen that CCN-T₂ has light absorption in the visible light band (below 420 nm), and its hydrogen production performance is better than that of bulk carbon nitride (PCN), but lower than that of CCN-T₀ , and its hydrogen production efficiency reaches 687µmol/g/h.

对比例3Comparative example 3

参照实施例1中的步骤进行反应，唯一不同的是将三聚氰酸和氯化锂之间的摩尔比改为2：1，之后滴加1 ml的甲醇于球磨罐中。以25 Hz的频率球磨2 h后，将白色产物在60℃下烘干，所得白色前驱体命名为LiCA-rate₁。图10为LiCA-rate₁的XRD谱图，结果表明其主要物相是三聚氰酸-氯化锂共晶（CA-LiCl）。高温煅烧、水洗过滤后得到的棕色产物命名为CCN-rate₁。图11为此条件下前驱体产物的 (a) XRD图和 (b) FTIR图, 结果表明CCN-rate₁同样具有良好的结晶性和氮化碳特征官能团，且同样具备PHI的晶体构型。图12为CCN-rate₁的 (a) 光催化产氢性能图，以及 (b) 固体紫外DRS图。可以看到CCN- rate₁具有可见光波段（420 nm以下）的光吸收，且产氢效率达到了2273 µmol/g/h，其产氢性能优于块状氮化碳（PCN），但低于CCN-T₀的产氢性能。The reaction was carried out referring to the steps in Example 1, the only difference was that the molar ratio between cyanuric acid and lithium chloride was changed to 2:1, and then 1 ml of methanol was added dropwise into the ball mill jar. After ball milling at a frequency of 25 Hz for 2 h, the white product was dried at 60 °C, and the resulting white precursor was named LiCA-rate₁ . Figure 10 is the XRD spectrum of LiCA-rate₁ , and the results show that its main phase is cyanuric acid-lithium chloride eutectic (CA-LiCl). The brown product obtained after high-temperature calcination, water washing and filtration is named CCN-rate₁ . Figure 11 shows the (a) XRD pattern and (b) FTIR pattern of the precursor product under this condition. The results show that CCN-rate₁ also has good crystallinity and carbon nitride characteristic functional groups, and also has the crystal configuration of PHI. Figure 12 is the (a) photocatalytic hydrogen production performance diagram and (b) solid ultraviolet DRS diagram of CCN-rate₁ . It can be seen that CCN-rate₁ has light absorption in the visible light band (below 420 nm), and its hydrogen production efficiency has reached 2273 µmol/g/h. Its hydrogen production performance is better than that of bulk carbon nitride (PCN), but lower than that of Hydrogen production performance of CCN-T₀ .

对比例4Comparative example 4

参照实施例1中的步骤进行反应，唯一不同的是将三聚氰酸和氯化锂之间的摩尔比改为1：2，之后滴加1ml的甲醇于球磨罐中。以25 Hz的频率球磨2 h后，将白色产物在60℃下烘干，所得白色前驱体命名为LiCA-rate₂。图13为LiCA-rate₂的XRD谱图，结果表明其主要物相是三聚氰酸-氯化锂共晶（CA-LiCl）。高温煅烧、水洗过滤后得到的棕色产物命名为CCN-rate₂。图14为此条件下产物的 (a) XRD图和 (b) FTIR图, 结果表明CCN-rate₂同样具有良好的结晶性和氮化碳特征官能团。图15为CCN-rate₂的 (a) 光催化产氢性能图，以及(b) 固体紫外DRS图。可以看到CCN-rate₂具有可见光波段（420 nm以下）的光吸收，且产氢效率达到了643 µmol/g/h，其产氢性能优于块状氮化碳（PCN），但低于CCN-T₀的产氢性能。The reaction was carried out referring to the steps in Example 1, the only difference was that the molar ratio between cyanuric acid and lithium chloride was changed to 1:2, and then 1ml of methanol was added dropwise into the ball mill jar. After ball milling at a frequency of 25 Hz for 2 h, the white product was dried at 60 °C, and the resulting white precursor was named LiCA-rate₂ . Figure 13 is the XRD spectrum of LiCA-rate₂ , and the results show that its main phase is cyanuric acid-lithium chloride eutectic (CA-LiCl). The brown product obtained after high-temperature calcination, water washing and filtration is named CCN-rate₂ . Figure 14 shows the (a) XRD pattern and (b) FTIR pattern of the product under this condition. The results show that CCN-rate₂ also has good crystallinity and carbon nitride characteristic functional groups. Figure 15 is the (a) photocatalytic hydrogen production performance diagram and (b) solid ultraviolet DRS diagram of CCN-rate₂ . It can be seen that CCN-rate₂ has light absorption in the visible light band (below 420 nm), and its hydrogen production efficiency has reached 643 µmol/g/h. Its hydrogen production performance is better than that of bulk carbon nitride (PCN), but lower than that of Hydrogen production performance of CCN-T₀ .

对比例5Comparative example 5

参照实施例1中的步骤进行反应，唯一不同的是将三聚氰酸替换成三聚氰胺，之后滴加1ml的甲醇于球磨罐中。以25 Hz的频率球磨2 h后，将白色产物在60℃下烘干，再将所得白色前驱体在氩气条件下高温煅烧、水洗过滤后得到的棕黄色产物命名为CCN-mel。图16为此条件下产物的 (a) XRD图和 (b) FTIR图, 结果表明CCN-mel同样具有良好的结晶性和氮化碳特征官能团，但晶体结构更接近于PTI的结构。图17为CCN-mel的 (a) SEM图， (b)氮气吸脱附曲线图，从SEM图中可以看到CCN-mel具有类棒状结构，从氮气吸脱附等温线图中可以发现CCN-mel相较于PCN具有更大的比表面积，BET比表面积达到了23.16 m²g^-1，低于CCN-T₀的比表面积。图18为CCN-mel的 (a) 光催化产氢性能图，以及(b) 固体紫外DRS图。可以看到CCN- mel具有可见光波段（420 nm以下）的光吸收，且产氢效率达到了214 µmol/g/h，其产氢性能优于块状氮化碳（PCN），但低于CCN-T₀的产氢性能。The reaction was carried out with reference to the steps in Example 1, the only difference was that cyanuric acid was replaced by melamine, and then 1ml of methanol was added dropwise into the ball mill jar. After ball milling at a frequency of 25 Hz for 2 h, the white product was dried at 60 °C, and the resulting white precursor was calcined at high temperature under argon, washed with water and filtered to obtain a brownish-yellow product named CCN-mel. Figure 16 shows the (a) XRD pattern and (b) FTIR pattern of the product under this condition. The results show that CCN-mel also has good crystallinity and carbon nitride characteristic functional groups, but the crystal structure is closer to the structure of PTI. Figure 17 is the (a) SEM image of CCN-mel, (b) the nitrogen adsorption-desorption curve. It can be seen from the SEM image that CCN-mel has a rod-like structure. It can be found from the nitrogen adsorption-desorption isotherm that CCN -mel has a larger specific surface area than PCN, and the BET specific surface area reaches 23.16 m² g^-1 , which is lower than that of CCN-T₀ . Figure 18 is the (a) photocatalytic hydrogen production performance diagram and (b) solid ultraviolet DRS diagram of CCN-mel. It can be seen that CCN-mel has light absorption in the visible light band (below 420 nm), and its hydrogen production efficiency has reached 214 µmol/g/h. Its hydrogen production performance is better than that of bulk carbon nitride (PCN), but lower than that of CCN -T₀ hydrogen production performance.

对比例6Comparative example 6

参照实施例1中的步骤进行反应，唯一不同的是将三聚氰酸替换成二氰二胺，之后滴加1ml的甲醇于球磨罐中。以25 Hz的频率球磨2 h后，将白色产物在60℃下烘干，再将所得白色前驱体在氩气条件下高温煅烧、水洗过滤后得到的棕色产物命名为CCN-DICY。图19为此条件下产物的 (a) XRD图和 (b) FTIR图, 结果表明CCN-DICY同样具有良好的结晶性和氮化碳特征官能团，但XRD衍射图中同样具有PTI相的出峰。图20为CCN-DICY的 (a) SEM图，(b) 氮气吸脱附曲线图，从SEM图中可以看到CCN-DICY具有类块状结构，从氮气吸脱附等温线图中可以发现CCN-DICY相较于PCN具有更大的比表面积，BET比表面积达到了56.25m²g^-1，低于CCN-T₀的比表面积。图21为CCN-DICY的 (a) 光催化产氢性能图，以及 (b) 固体紫外DRS图。可以看到CCN- DICY具有可见光波段（420 nm以下）的光吸收，且产氢效率达到了425 µmol/g/h，其产氢性能优于块状氮化碳（PCN），但低于CCN-T₀的产氢性能。The reaction was carried out referring to the steps in Example 1, the only difference was that cyanuric acid was replaced by dicyandiamide, and then 1 ml of methanol was added dropwise into the ball mill jar. After ball milling at a frequency of 25 Hz for 2 h, the white product was dried at 60 °C, and the resulting white precursor was calcined at high temperature under argon, washed with water and filtered to obtain a brown product named CCN-DICY. Figure 19 (a) XRD pattern and (b) FTIR pattern of the product under this condition, the results show that CCN-DICY also has good crystallinity and carbon nitride characteristic functional groups, but the XRD diffraction pattern also has the peak of the PTI phase . Figure 20 is the (a) SEM image of CCN-DICY, (b) the nitrogen adsorption-desorption curve. It can be seen from the SEM image that CCN-DICY has a block-like structure. It can be found from the nitrogen adsorption-desorption isotherm CCN-DICY has a larger specific surface area than PCN, and the BET specific surface area reaches 56.25m² g^-1 , which is lower than that of CCN-T₀ . Figure 21 is the (a) photocatalytic hydrogen production performance diagram and (b) solid ultraviolet DRS diagram of CCN-DICY. It can be seen that CCN-DICY has light absorption in the visible light band (below 420 nm), and its hydrogen production efficiency has reached 425 µmol/g/h. Its hydrogen production performance is better than that of bulk carbon nitride (PCN), but lower than that of CCN -T₀ hydrogen production performance.

对比例7Comparative example 7

参照实施例1中的步骤进行反应1，唯一不同的是改变煅烧温度，以2.3^oC/min的升温速率升至500 °C并保温4 h，冷却至室温后得到棕黄色产物，将其水洗后过滤，得到最终产物CCN-T₃，由图22可以发现得到的氮化碳并不是结晶性氮化碳。Reaction 1 is carried out with reference to the steps in Example 1, the only difference is to change the calcination temperature, rise to 500 ° C with a heating rate of 2.3^° C/min and keep it warm for 4 h, after cooling to room temperature, a tan product is obtained, which is washed with water After filtration, the final product CCN-T₃ was obtained, and it can be found from Figure 22 that the obtained carbon nitride was not crystalline carbon nitride.

对比例8Comparative example 8

参照实施例1中的步骤进行反应，唯一不同的是改变煅烧温度，以2.3^oC/min的升温速率升至450 °C并保温4 h，冷却至室温后得到棕黄色产物，将其水洗后过滤，得到最终产物CCN-T₄，由图22可以发现得到的氮化碳并不是结晶性氮化碳。React with reference to the step in Example 1, the only difference is to change the calcination temperature, rise to 450 ° C with a heating rate of 2.3^o C/min and keep it warm for 4 h, after cooling to room temperature, a tan product is obtained, which is washed with water Filtration to obtain the final product CCN-T₄ , it can be found from Figure 22 that the obtained carbon nitride is not crystalline carbon nitride.

对比例9Comparative example 9

参照实施例1中的步骤进行反应，唯一不同的是改变煅烧温度，以2.3^oC/min的升温速率升至400 °C并保温4 h，冷却至室温后得到棕黄色产物，将其水洗后过滤，得到最终产物CCN-T₅，由图22可以发现得到的氮化碳并不是结晶性氮化碳。React with reference to the step in Example 1, the only difference is to change the calcination temperature, rise to 400 ° C with a heating rate of 2.3^° C/min and keep warm for 4 h, after cooling to room temperature, a brownish-yellow product is obtained, which is washed with water Filtration to obtain the final product CCN-T₅ , it can be found from Figure 22 that the obtained carbon nitride is not crystalline carbon nitride.

对比例10Comparative example 10

本实施例的其它步骤同实施例1，唯一不同的是改变煅烧温度，以2.3^oC/min的升温速率升至350 °C并保温4 h，冷却至室温后得到棕黄色产物，将其水洗后过滤，得到最终产物CCN-T₆，由图22可以发现得到的氮化碳并不是结晶性氮化碳。The other steps of this embodiment are the same as in Example 1, the only difference is that the calcination temperature is changed, and the temperature rises to 350 ° C with a heating rate of 2.3^° C/min and is kept for 4 h. After cooling to room temperature, a brownish-yellow product is obtained, which is washed with water After filtration, the final product CCN-T₆ was obtained, and it can be found from Figure 22 that the obtained carbon nitride was not crystalline carbon nitride.

Claims

1. A preparation method of high-crystallinity carbon nitride based on cyanuric acid-lithium chloride eutectic is characterized by comprising the following steps:

step one, synthesizing LiCA precursor by ball milling method

Placing cyanuric acid and lithium chloride in a ball milling tank according to a molar ratio of 1;

step two, high-temperature calcination is carried out to prepare high-crystallinity carbon nitride

And (4) placing the precursor LiCA obtained in the step one in a tube furnace, calcining at high temperature in an argon atmosphere, washing with water, filtering and drying to obtain the high-crystallinity carbon nitride.

2. The method of claim 1, wherein in step 1, the frequency of ball milling is 5 to 25 Hz and the time is 0.5 to 2 hours.

3. The process according to claim 1, wherein in step 1, 0.5 to 2 ml of methanol is added dropwise, based on 0.01mol of cyanuric acid.

4. The method of claim 1, wherein in step 1, the precursor is dried at a temperature of 60-80 ℃ for 1-2 hours.

5. The method of claim 1, wherein in step 2, the calcination is carried out at 550 ℃ for 4 h.

6. The method as claimed in claim 1, wherein in step 2, the filtration is performed by suction filtration, and the drying temperature of the product is 60-80 ℃ for 8-24 h.

7. Highly crystalline carbon nitride prepared by the method as set forth in any one of claims 1 to 6.

8. Use of highly crystalline carbon nitride prepared by the method according to any one of claims 1 to 6 in photocatalytic hydrogen production reaction.