A ruthenium-loaded crystalline carbon nitride / doped nanodiamond composite material and its preparation method and application

Abstract

The present invention belongs to the field of photocatalysis technology and discloses a ruthenium-loaded crystalline carbon nitride / doped nanodiamond composite material and its preparation method and application. The composite material is Ru / CCN / XDND. Preparation method: (1) preparing crystalline carbon nitride nanosheets, namely CCN nanosheets; (2) preparing ruthenium-loaded crystalline carbon nitride nanosheets, namely Ru / CCN nanosheets; (3) pretreating doped nanodiamonds, namely XDND; (4) grinding and mixing the Ru / CCN nanosheets obtained in step (2) and the XDND obtained in step (3) in a mass ratio of (80-95) to (5-20) and a sum of the two to 100, and annealing at 150-250°C for 0.5-1.5 h under a protective atmosphere to obtain a Ru / CCN / XDND composite material. Application of the ruthenium-loaded crystalline carbon nitride / doped nanodiamond composite material as a photocatalyst in water splitting to produce hydrogen. The photocatalytic water splitting hydrogen production rate of the Ru / CCN / XDND prepared by the present invention is significantly improved compared with that of pure CCN and pure bulk CN.

Description

Technical Field

[0001] The present invention belongs to the technical field of photocatalysis, and in particular relates to a ruthenium-loaded crystalline carbon nitride / doped nanodiamond composite material, a preparation method and an application thereof. Background Art

[0002] The search for clean and sustainable energy is a hot topic in current research. Among them, photocatalytic water splitting to produce hydrogen is considered to be an economical and environmentally friendly technology. In the photochemical conversion process, enhancing charge separation and transfer capabilities is the key to improving photocatalytic activity. In particular, constructing heterojunction structures and modifying the design at the interface are crucial to further enhance charge separation and migration. At present, many metal semiconductors have been reported to have good photocatalytic activity, such as CdS, ZnIn2S4, BiVO4, etc., but their high cost and environmental issues have attracted widespread attention.

[0003] In contrast, graphitic carbon nitride (g-CN), a nonmetallic two-dimensional semiconductor material, has been shown to be an ideal semiconductor photocatalyst due to its excellent physicochemical stability, nontoxicity, low cost, and suitable band structure. However, the efficiency of single CN as a photocatalyst for water splitting to produce hydrogen is extremely low, making it unsatisfactory in practical applications. The main reasons are poor conductivity, rapid recombination of photogenerated electrons and holes in the bulk phase, and relatively low specific surface area. In addition, its poor crystallinity leads to incomplete polymerization of -NH2 in the amorphous structure, resulting in CN with numerous internal structural defects. These defects act as traps for charge recombination, significantly inhibiting the kinetics of hydrogen evolution. Therefore, catalyst modification and structural design are necessary. Ultrathin and highly crystalline CN nanosheets can effectively eliminate internal defects and improve the utilization of photogenerated carriers, thereby achieving efficient hydrogen production. Furthermore, constructing heterojunctions is an effective strategy to enhance the photocatalytic activity of CN, particularly by constructing composite materials with tight electronic coupling and efficient charge transfer pathways. Summary of the Invention

[0004] In order to solve the problem of low efficiency of photocatalytic water decomposition to produce hydrogen by CN in the prior art, the present invention aims to provide a ruthenium-loaded crystalline carbon nitride / doped nanodiamond composite material and its preparation method and application.

[0005] To achieve the above object, the technical solution adopted by the present invention is as follows:

[0006] A ruthenium-loaded crystalline carbon nitride / doped nanodiamond composite material is disclosed. The composite material is Ru / CCN / XDND, where Ru represents ruthenium, CCN represents crystalline carbon nitride, XDND represents doped nanodiamond, and X represents a doping element, which is a non-metallic element. The ruthenium loading in the ruthenium-loaded crystalline carbon nitride is 0.5-2 wt%, the doping amount of the doping element X in the doped nanodiamond is 0.1-2 wt%, and the mass ratio of the doped nanodiamond in the entire catalyst is 5-20 wt%.

[0007] Preferably, the non-metallic element is boron or nitrogen.

[0008] A method for preparing a ruthenium-loaded crystalline carbon nitride / doped nanodiamond composite material, comprising the following steps:

[0009] (1) Preparation of crystalline carbon nitride nanosheets, namely CCN nanosheets;

[0010] (2) preparing ruthenium-supported crystalline carbon nitride nanosheets, i.e., Ru / CCN nanosheets, according to the following method (i) or (ii);

[0011] (i) dispersing the CCN nanosheets obtained in step (1) in water, adding a ruthenium trichloride aqueous solution according to the ruthenium loading amount, stirring evenly, reducing the mixture by light or a reducing agent, and then centrifuging and drying to obtain Ru / CCN nanosheets;

[0012] (ii) dispersing the CCN nanosheets obtained in step (1) in water, adding a ruthenium trichloride aqueous solution according to the ruthenium loading amount, stirring evenly and evaporating to dryness, and then reducing with H2 or H2 / N2 mixed gas to obtain Ru / CCN nanosheets;

[0013] (3) Pretreatment of doped nanodiamonds, namely XDND;

[0014] Anneal the XDND at 400-500 °C in air for 0.5-1.5 h;

[0015] (4) Grind and mix the Ru / CCN nanosheets obtained in step (2) and the XDND obtained in step (3) in a mass ratio of (80-95) to (5-20) and a sum of the two to 100, and anneal at 150-250 °C for 0.5-1.5 h under a protective atmosphere to obtain a Ru / CCN / XDND composite material.

[0016] Preferably, the preparation process of step (1) is as follows: dissolving the nitrogen-rich precursor and the template in 1# water, stirring evenly and then drying, and then calcining at 400~650℃ for 2~6 hours in a reaction atmosphere; dispersing all the calcined samples in 2# water, stirring evenly, hydrothermally treating at 100~180℃ for 0.5~2 hours, cooling, washing, and drying to obtain CCN nanosheets.

[0017] Preferably, in step (1), the mass ratio of nitrogen-rich precursor to template is 1: (0-0.2) and the amount of template does not include 0, and the nitrogen-rich precursor to 1# water to 2# water is 5 g: (5-30) mL: (20-60) mL.

[0018] Preferably, in step (1), the nitrogen-rich precursor is one or more of urea, melamine, dicyandiamide, monocyanamide, and thiourea; and the template is one or more of sodium bicarbonate, sodium carbonate, magnesium carbonate, ammonium chloride, ammonium persulfate, and potassium chloride.

[0019] Preferably, the reaction atmosphere is air, nitrogen or a nitrogen-hydrogen mixture.

[0020] Preferably, in the methods (i) and (ii) of step (2), the raw material dosage ratio is CCN nanosheets: water = 0.5 g: (10-50) mL; and the concentration of the ruthenium trichloride aqueous solution is 2-20 mM.

[0021] Preferably, in step (2), the light in the photoreduction is visible light or simulated sunlight; the reducing agent is sodium borohydride or hydrazine hydrate, and the amount of the reducing agent is in excess relative to ruthenium; the time for photoreduction or reducing agent reduction is 0.5 to 2 hours; the temperature for H2 or H2 / N2 mixed gas reduction is 150 to 200°C, and the proportion of H2 in the H2 / N2 mixed gas is 5 to 20 v%.

[0022] Preferably, in step (3), the XDND is first immersed in a concentrated acid oxidizing solution, heated and stirred at 30-60°C for 0.5-2 h, washed with water until neutral, vacuum-dried, and then annealed; the concentrated acid oxidizing solution is one or a mixture of concentrated nitric acid, concentrated sulfuric acid, and concentrated hydrochloric acid.

[0023] Application of a ruthenium-loaded crystalline carbon nitride / doped nanodiamond composite material as a photocatalyst in water splitting to produce hydrogen.

[0024] In the present invention, the doped nanodiamond can be purchased commercially or prepared by referring to the existing technology.

[0025] Beneficial effects: The present invention uses a template method in conjunction with a simple self-assembly strategy to prepare a Ru / CCN / XDND composite material. The photocatalytic water splitting hydrogen production rate of Ru / CCN / XDND is significantly improved compared with that of pure CCN and pure bulk CN (the photocatalytic hydrogen evolution rate of the Ru / CCN / BDND composite material reaches a maximum of 8.12 mmol g -1 h -1 ), providing a new solution for the early realization of industrial production. Furthermore, the preparation method of the present invention offers numerous advantages, including simplicity, low cost, high light utilization, and high charge separation and transfer efficiency, and holds significant potential for application in the green energy sector. Therefore, the present invention represents a highly significant technology for efficiently obtaining clean energy. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 : X-ray diffraction (XRD) patterns of CCN and CN prepared in Example 1 and Comparative Example 1.

[0027] Figure 2 : Scanning electron micrograph of the CCN prepared in Example 1.

[0028] Figure 3 : X-ray photoelectron spectrum of CCN prepared in Example 1.

[0029] Figure 4 : Ru prepared in Example 1 1.0 / CCN / BDND 10.0 Composite materials, Ru 1.0 / CCN and XRD patterns of BDND obtained after pretreatment in step (3). DETAILED DESCRIPTION

[0030] The present invention is described in detail below through specific examples, in which many specific details are set forth to provide a full understanding of the objects, features, and advantages of the present invention. However, these examples are intended only to illustrate the present invention and are not intended to limit the actual scope of protection of the present invention in any form. Those skilled in the art may implement any form of changes and modifications to the present invention without violating the connotation of the present invention. Therefore, the present invention is not limited to the specific examples disclosed below.

[0031] Example 1

[0032] A method for preparing a ruthenium-loaded crystalline carbon nitride / doped nanodiamond composite material, comprising the following steps:

[0033] (1) Dissolve 5 g of dicyandiamide and 0.25 g of sodium bicarbonate in 15 mL of deionized water, stir evenly, and freeze-dry to remove the solvent to obtain a white powder. Then put it into a crucible with a lid and place it in a muffle furnace. Heat it to 550 °C at a heating rate of 2 °C / min in air and calcine it for 4 h. Disperse the calcined sample in 60 mL of deionized water, stir it at room temperature for 1 h, transfer it to a high-pressure reactor and hydrothermally treat it at 180 °C for 1 h. After cooling, centrifuge, wash, and dry it to obtain high-crystalline carbon nitride ultrathin nanosheets, which are labeled as CCN nanosheets.

[0034] (2) 0.5 g of CCN nanosheets were dispersed in 20 mL of deionized water by ultrasonic dispersion, and 5 mL of ruthenium trichloride aqueous solution (10 mM) was added. After stirring for 0.5 h, the mixture was photo-reduced for 1 h. After centrifugation, washing and drying, ruthenium-loaded crystalline carbon nitride nanosheets (Ru loading of 1.0 wt%) were obtained, which were labeled as Ru 1.0 / CCN;

[0035] (3) BDND (boron-doped nanodiamond, boron doping amount of 0.7 wt%, purchased from Changsha Sanbid Superhard Materials Co., Ltd.) powder was soaked in an oxidizing solution of concentrated sulfuric acid: concentrated nitric acid (volume ratio of 3:1), heated at 40 °C and stirred for 1 h, then repeatedly centrifuged and washed with deionized water until the pH value of the solution was neutral, and vacuum dried at 60 °C. The obtained solid was placed in a muffle furnace and annealed at 450 °C in air atmosphere for 0.5 h to remove the sp-coated surface. 2 carbon;

[0036] (4) The product obtained in step (2) (0.45 g Ru 1.0 / CCN) and the product obtained in step (3) (0.05 g BDND) were put into a ball mill and ground for 1 h. After being mixed evenly, they were added to a crucible and heated to 200 °C at a heating rate of 5 °C / min in a tube furnace under nitrogen protection. After annealing for 1 h, Ru-containing 10.0 wt% BDND was obtained. 1.0 / CCN / BDND 10.0 Composite materials.

[0037] Example 2

[0038] A method for preparing a ruthenium-loaded crystalline carbon nitride / doped nanodiamond composite material, comprising the following steps:

[0039] (1) Same as step (1) in Example 1;

[0040] (2) After ultrasonic dispersion of 0.5 g CCN nanosheets in 20 mL deionized water, 1 mL of ruthenium trichloride aqueous solution (10 mM) was added, stirred for 0.5 h, and photoreduced for 1 h to obtain ruthenium-loaded crystalline carbon nitride nanosheets (Ru loading of 0.2 wt%), which were labeled as Ru 0.2 / CCN;

[0041] (3) Same as step (3) in Example 1;

[0042] (4) The product obtained in step (2) (0.45 g Ru 0.2 / CCN) and the product obtained in step (3) (0.05 g BDND) were put into a ball mill and ground for 1 h. After being mixed evenly, they were added to a crucible and heated to 200 °C at a heating rate of 5 °C / min in a tube furnace under nitrogen protection. After annealing for 1 h, Ru-containing 10.0 wt% BDND was obtained. 0.2 / CCN / BDND 10.0 Composite materials.

[0043] Example 3

[0044] A method for preparing a ruthenium-loaded crystalline carbon nitride / doped nanodiamond composite material, comprising the following steps:

[0045] (1) Same as step (1) in Example 1;

[0046] (2) After ultrasonic dispersion of 0.5 g CCN nanosheets in 20 mL deionized water, 2.5 mL of 10 mM ruthenium chloride aqueous solution was added, stirred for 0.5 h, and photoreduced for 1 h to obtain ruthenium-loaded crystalline carbon nitride nanosheets (Ru loading of 0.5 wt%), which were labeled as Ru 0.5 / CCN;

[0047] (3) Same as step (3) in Example 1;

[0048] (4) The product obtained in step (2) (0.45 g Ru 0.5 / CCN) and the product obtained in step (3) (0.05 g BDND) were put into a ball mill and ground for 1 h. After being mixed evenly, they were added to a crucible and heated to 200 °C at a heating rate of 5 °C / min in a tube furnace under nitrogen protection. After annealing for 1 h, Ru-containing 10.0 wt% BDND was obtained. 0.5 / CCN / BDND 10.0 Composite materials.

[0049] Example 4

[0050] A method for preparing a ruthenium-loaded crystalline carbon nitride / doped nanodiamond composite material, comprising the following steps:

[0051] (1) Same as step (1) in Example 1;

[0052] (2) After ultrasonic dispersion of 0.5 g CCN nanosheets in 20 mL deionized water, 10 mL of ruthenium trichloride aqueous solution (10 mM) was added, stirred for 0.5 h, and photoreduced for 1 h to obtain ruthenium-loaded crystalline carbon nitride nanosheets (Ru loading of 2.0 wt%), which were labeled as Ru 2.0 / CCN;

[0053] (3) Same as step (3) in Example 1;

[0054] (4) The product obtained in step (2) (0.45 g Ru 2.0 / CCN) and the product obtained in step (3) (0.05 g BDND) were put into a ball mill and ground for 1 h. After being mixed evenly, they were added to a crucible and heated to 200 °C at a heating rate of 5 °C / min in a tube furnace under nitrogen protection. After annealing for 1 h, Ru-containing 10.0 wt% BDND was obtained. 2.0 / CCN / BDND 10.0 Composite materials.

[0055] Example 5

[0056] A method for preparing a ruthenium-loaded crystalline carbon nitride / doped nanodiamond composite material, comprising the following steps:

[0057] (1) Same as step (1) in Example 1;

[0058] (2) Same as step (2) in Example 1;

[0059] (3) Same as step (3) in Example 1;

[0060] (4) The product obtained in step (2) (0.495 g Ru 1.0 / CCN) and the product obtained in step (3) (0.005 g BDND) were put into a ball mill and ground for 1 h. After being mixed evenly, they were added to a crucible and heated to 200 °C at a heating rate of 5 °C / min in a tube furnace under nitrogen protection. After annealing for 1 h, Ru-containing 1.0 wt% BDND was obtained. 1.0 / CCN / BDND 1.0 Composite materials.

[0061] Example 6

[0062] A method for preparing a ruthenium-loaded crystalline carbon nitride / doped nanodiamond composite material, comprising the following steps:

[0063] (1) Same as step (1) in Example 1;

[0064] (2) Same as step (2) in Example 1;

[0065] (3) Same as step (3) in Example 1;

[0066] (4) The product obtained in step (2) (0.49 g Ru 1.0 / CCN) and the product obtained in step (3) (0.01 g BDND) were put into a ball mill and ground for 1 h. After being mixed evenly, they were added to a crucible and heated to 200 °C at a heating rate of 5 °C / min in a tube furnace under nitrogen protection. After annealing for 1 h, Ru-containing 2.0 wt% BDND was obtained. 1.0 / CCN / BDND 2.0 Composite materials.

[0067] Example 7

[0068] A method for preparing a ruthenium-loaded crystalline carbon nitride / doped nanodiamond composite material, comprising the following steps:

[0069] (1) Same as step (1) in Example 1;

[0070] (2) Same as step (2) in Example 1;

[0071] (3) Same as step (3) in Example 1;

[0072] (4) The product obtained in step (2) (0.475 g Ru 1.0 / CCN) and the product obtained in step (3) (0.025 g BDND) were put into a ball mill and ground for 1 h. After being mixed evenly, they were added to a crucible and heated to 200 °C at a heating rate of 5 °C / min in a tube furnace under nitrogen protection. After annealing for 1 h, Ru-containing 5.0 wt% BDND was obtained. 1.0 / CCN / BDND 5.0 Composite materials.

[0073] Example 8

[0074] A method for preparing a ruthenium-loaded crystalline carbon nitride / doped nanodiamond composite material, comprising the following steps:

[0075] (1) Same as step (1) in Example 1;

[0076] (2) Same as step (2) in Example 1;

[0077] (3) Same as step (3) in Example 1;

[0078] (4) The product obtained in step (2) (0.425 g Ru 1.0 / CCN) and the product obtained in step (3) (0.075 g BDND) were put into a ball mill and ground for 1 h. After being mixed evenly, they were added to a crucible and heated to 200 °C at a heating rate of 5 °C / min in a tube furnace under nitrogen protection. After annealing for 1 h, Ru-containing 15.0 wt% BDND was obtained. 1.0 / CCN / BDND 15.0 Composite materials.

[0079] Example 9

[0080] A method for preparing a ruthenium-loaded crystalline carbon nitride / doped nanodiamond composite material, comprising the following steps:

[0081] (1) Same as step (1) in Example 1;

[0082] (2) Same as step (2) in Example 1;

[0083] (3) Same as step (3) in Example 1;

[0084] (4) The product obtained in step (2) (0.4 g Ru 1.0 / CCN) and the product obtained in step (3) (0.1 g BDND) were put into a ball mill and ground for 1 h. After being mixed evenly, they were added to a crucible and heated to 200 °C at a heating rate of 5 °C / min in a tube furnace under nitrogen protection. After annealing for 1 h, Ru-containing 20.0 wt% BDND was obtained. 1.0 / CCN / BDND 20.0 Composite materials.

[0085] Example 10

[0086] A method for preparing a ruthenium-loaded crystalline carbon nitride / doped nanodiamond composite material, comprising the following steps:

[0087] (1) Same as step (1) in Example 1;

[0088] (2) Same as step (2) in Example 1;

[0089] (3) Same as step (3) in Example 1;

[0090] (4) The product obtained in step (2) (0.35 g Ru 1.0 / CCN) and the product obtained in step (3) (0.15 g BDND) were put into a ball mill and ground for 1 h. After being mixed evenly, they were added to a crucible and heated to 200 °C at a heating rate of 5 °C / min in a tube furnace under nitrogen protection. After annealing for 1 h, Ru-containing 30.0 wt% BDND was obtained.1.0 / CCN / BDND 30.0 Composite materials.

[0091] Example 11

[0092] A method for preparing a ruthenium-loaded crystalline carbon nitride / doped nanodiamond composite material, comprising the following steps:

[0093] (1) Same as step (1) in Example 1;

[0094] (2) Same as step (2) in Example 1;

[0095] (3) 100 mg of nitrogen-doped graphene powder (nitrogen content of 0.9 wt%) was placed in 20 mL of anhydrous ethanol, ultrasonically dispersed for 0.5 h, and then continuously irradiated with a 532 nm laser beam with a pulse power of 200 mJ under vigorous stirring until no obvious black solid powder was suspended. After that, the irradiation was stopped, and the solid was centrifuged and dried. The obtained solid was placed in a muffle furnace and annealed at 400 °C in an air atmosphere for 0.5 h to remove the sp2 carbon covering the surface, thereby obtaining NDND (nitrogen-doped nanodiamond) with a nitrogen content of 0.9 wt%.

[0096] (4) The product obtained in step (2) (0.45 g Ru 1.0 / CCN) and the product obtained in step (3) (0.05 g NDND) were put into a ball mill and ground for 1 h. After being mixed evenly, they were added to a crucible and heated to 200 °C at a heating rate of 5 °C / min in a tube furnace under nitrogen protection. After annealing for 1 h, Ru containing 10.0 wt% NDND was obtained. 1.0 / CCN / NDND 10.0 Composite materials.

[0097] Example 12

[0098] A method for preparing a ruthenium-loaded crystalline carbon nitride / doped nanodiamond composite material, comprising the following steps:

[0099] (1) Same as step (1) in Example 1;

[0100] (2) Same as step (2) in Example 1;

[0101] (3) 100 mg of graphite powder and 4 mg of cobalt acetate were placed in 20 mL of anhydrous ethanol, ultrasonically dispersed for 0.5 h, and then continuously irradiated with a 532 nm laser beam with a pulse power of 200 mJ under vigorous stirring until no obvious black solid powder was suspended. After that, the irradiation was stopped, and the solid was centrifuged and dried. The obtained solid was placed in a muffle furnace and annealed at 450 ° C in an air atmosphere for 0.5 h to remove the sp2 carbon covering the surface, thereby obtaining CDND (cobalt-doped nanodiamond), in which the Co content was about 0.5 wt%;

[0102] (4) The product obtained in step (2) (0.45 g Ru 1.0 / CCN) and the product obtained in step (3) (0.05 gCDND) were put into a ball mill and ground for 1 h. After being mixed evenly, they were added to a crucible and heated to 200 °C at a heating rate of 5 °C / min in a tube furnace under nitrogen protection. After annealing for 1 h, Ru-containing 10.0 wt% CDND was obtained. 1.0 / CCN / CDND 10.0 Composite materials.

[0103] Comparative Example 1

[0104] A method for preparing a ruthenium-loaded ordinary carbon nitride / doped nanodiamond composite material, comprising the following steps:

[0105] (1) Place 5 g of dicyandiamide in a covered crucible in a muffle furnace, heat the mixture to 550 °C at a heating rate of 2 °C / min in air, and calcine for 4 h to obtain ordinary bulk carbon nitride (CN);

[0106] (2) After ultrasonic dispersion of 0.5 g of bulk CN in 20 mL of deionized water, 5 mL of 10 mM ruthenium chloride aqueous solution was added, stirred for 0.5 h, and photoreduced for 1 h to obtain ruthenium-loaded ordinary carbon nitride nanosheets (Ru loading of 1.0 wt%), which were labeled Ru 1.0 / CN;

[0107] (3) Same as step (3) in Example 1;

[0108] (4) The product obtained in step (2) (0.45 g Ru 1.0 / CN) and the product obtained in step (3) (0.05 g BDND) were put into a ball mill and ground for 1 h. After being mixed evenly, they were added to a crucible and heated to 200 °C at a heating rate of 5 °C / min in a tube furnace under nitrogen protection. After annealing for 1 h, Ru-containing 10.0 wt% BDND was obtained. 1.0 / CN / BDND 10.0 Composite materials.

[0109] Product structure characterization

[0110] Figure 1 The X-ray diffraction (XRD) patterns of CCN and CN prepared in Example 1 and Comparative Example 1 are shown in FIG. Figure 1 It can be seen that CN and CCN have two peaks at 12.9° and 27.4°, corresponding to the in-plane repeating triazine units of the (100) crystal plane and the interlayer stacking of the planar conjugated system of the (002) crystal plane, respectively. The diffraction peak of CCN is significantly enhanced, indicating that CCN has a higher degree of crystallinity.

[0111] Figure 2 This is a scanning electron microscope image of the CCN prepared in Example 1. Figure 2 It can be seen from the figure that CCN presents a typical two-dimensional nanosheet morphology.

[0112] Figure 3 The X-ray photoelectron spectrum of CCN prepared in Example 1. Figure 3 It can be seen that C-NH x and NC=N characteristic peaks, C=NC, N-C3, CNH appeared in the N 1s spectrum x The characteristic peaks of the surface chemical state and elemental composition of CCN were confirmed.

[0113] Figure 4 Ru prepared in Example 1 1.0 / CCN / BDND 10.0 Composite materials, Ru 1.0 / CCN and XRD patterns of BDND obtained after pretreatment in step (3). Figure 4 It can be seen that the two peaks at 43.9° and 75.2° in the BDND sample correspond to the (111) and (220) crystal planes of diamond, respectively; the two peaks at 12.9° and 27.4° in the CCN sample are attributed to the characteristic peaks of CCN, and the characteristic peaks of Ru are difficult to see in the composite material, which may be caused by its lower loading; 1.0 / CCN / BDND 10.0 The peaks of CCN and BDND were observed in the composites, confirming the successful synthesis of the composites.

[0114] Performance Testing

[0115] Any one of the products prepared in Examples 1-12, the product prepared in Comparative Example 1, the CCN prepared in step (1) of Example 1, and the CN prepared in step (1) of Comparative Example 1 was selected as a catalyst. 25 mg of the catalyst was added to 100 mL of an aqueous solution containing 10 v% triethanolamine, and after ultrasonic dispersion for 10 min, the mixture was added to a 250 mL Beijing Perfil photocatalytic reactor. After vacuuming to remove the air, a 300 W xenon lamp was used as a light source to provide full-spectrum light irradiation to the reaction solution. Samples were taken after a certain period of time, and the generated hydrogen was detected using a Japanese Shimadzu GC-81 chromatograph and quantitatively analyzed.

[0116] The measured photocatalytic hydrogen evolution rate results are shown in Table 1. It can be seen from Table 1 that:

[0117] (1) BDND and Ru have an important influence on improving the photocatalytic hydrogen production activity of Ru / CCN / BDND. The optimal mass fraction of BDND is 5-20 wt%, and the optimal mass fraction of Ru is 0.5-2 wt%. The photocatalytic hydrogen production effect cannot be achieved below or above the optimal range;

[0118] (2) Doping elements have a good promoting effect on photocatalytic performance, with boron being the best and nitrogen being the second. This is because the band gap and band structure position of diamond doped with different elements are very different, which has a great influence on the photocatalytic activity of the catalyst;

[0119] (3) Ru prepared by the present invention 1.0 / CCN / BDND 10.0 The photocatalytic hydrogen evolution rate of the catalyst was 8.12 mmol g -1 h -1 The photocatalytic hydrogen evolution rate of CCN was 0.63 mmol g -1 h -1 The photocatalytic hydrogen evolution rate of ordinary bulk CN is 0.12 mmol g -1 h -1 , Ru 1.0 / CCN / BDND 10.0 The hydrogen evolution rate is increased by 13.5 times compared with CCN and 67.7 times compared with ordinary CN.

[0120]

Claims

1. A ruthenium-supported crystalline carbon nitride / doped nanodiamond composite material, characterized in that: The composite material is Ru / CCN / XDND, where Ru represents ruthenium, CCN represents crystalline carbon nitride, XDND represents doped nanodiamond, and X represents a doping element, which is boron or nitrogen. The loading amount of ruthenium in the ruthenium-loaded crystalline carbon nitride is 0.5-2 wt%, the doping amount of the doping element X in the doped nanodiamond is 0.1-2 wt%, and the mass ratio of the doped nanodiamond in the entire ruthenium-loaded crystalline carbon nitride / doped nanodiamond composite material is 5-20 wt%.

2. A method for preparing the ruthenium-supported crystalline carbon nitride / doped nanodiamond composite material as claimed in claim 1, characterized in that: Here are the steps: (1) Preparation of crystalline carbon nitride nanosheets, namely CCN nanosheets; (2) preparing ruthenium-supported crystalline carbon nitride nanosheets, i.e., Ru / CCN nanosheets, according to the following method (i) or (ii); (i) dispersing the CCN nanosheets obtained in step (1) in water, adding a ruthenium trichloride aqueous solution according to the ruthenium loading amount, stirring evenly, reducing the mixture by light or a reducing agent, and then centrifuging and drying to obtain Ru / CCN nanosheets; (ii) dispersing the CCN nanosheets obtained in step (1) in water, adding a ruthenium trichloride aqueous solution according to the ruthenium loading amount, stirring evenly and evaporating to dryness, and then reducing with H2 or H2 / N2 mixed gas to obtain Ru / CCN nanosheets; (3) Pre-treating doped nanodiamonds (XDNDs); annealing the XDNDs at 400-500 °C in air for 0.5-1.5 h; (4) Grind and mix the Ru / CCN nanosheets obtained in step (2) and the XDND obtained in step (3) in a mass ratio of (80-95) : (5-20) and a sum of their mass proportions being 100%, and anneal at 150-250 °C for 0.5-1.5 h under a protective atmosphere to obtain a Ru / CCN / XDND composite material.

3. The method for preparing the ruthenium-supported crystalline carbon nitride / doped nanodiamond composite material according to claim 2, wherein: The preparation process of step (1) is as follows: dissolving the nitrogen-rich precursor and the template in 1# water, stirring evenly and then drying, and then calcining at 400~650℃ for 2~6 hours in a reaction atmosphere; dispersing all the calcined samples in 2# water, stirring evenly, hydrothermally treating at 100~180℃ for 0.5~2 hours, cooling, washing, and drying to obtain CCN nanosheets; the reaction atmosphere is air, nitrogen, or a nitrogen-hydrogen mixture.

4. The method for preparing the ruthenium-supported crystalline carbon nitride / doped nanodiamond composite material according to claim 3, wherein: In step (1), based on the mass ratio, nitrogen-rich precursor: template = 1: (0-0.2) and the amount of template does not include 0, nitrogen-rich precursor: 1# water: 2# water = 5 g: (5-30) mL: (20-60) mL.

5. The method for preparing the ruthenium-supported crystalline carbon nitride / doped nanodiamond composite material according to claim 3 or 4, characterized in that: In step (1), the nitrogen-rich precursor is one or more of urea, melamine, dicyandiamide, monocyanamide, and thiourea; and the template is one or more of sodium bicarbonate, sodium carbonate, magnesium carbonate, ammonium chloride, ammonium persulfate, and potassium chloride.

6. The method for preparing the ruthenium-supported crystalline carbon nitride / doped nanodiamond composite material according to claim 2, wherein: In step (2), the raw material dosage ratio is CCN nanosheets: water = 0.5 g: (10-50) mL; the concentration of the ruthenium trichloride aqueous solution is 2-20 mM.

7. The method for preparing the ruthenium-supported crystalline carbon nitride / doped nanodiamond composite material according to claim 2, wherein: In step (3), the XDND is first immersed in a concentrated acid oxidizing solution, heated and stirred at 30-60 °C for 0.5-2 h, washed with water until neutral, vacuum-dried, and then annealed; the concentrated acid oxidizing solution is one or a mixture of concentrated nitric acid, concentrated sulfuric acid, and concentrated hydrochloric acid.

8. Use of the ruthenium-supported crystalline carbon nitride / doped nanodiamond composite material as claimed in claim 1 as a photocatalyst in water splitting to produce hydrogen.

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