A CdS / CdNCN nanocatalyst with a spherical structure and its preparation method and application

Abstract

The present invention belongs to the field of photocatalytic materials, and discloses a CdS / CdNCN nanocatalyst with a ball-shaped structure, a preparation method thereof, and an application thereof. The CdS / CdNCN nanocatalyst with a ball-shaped structure is prepared by the following method: cadmium salt and thiourea are added to water, the molar mass ratio of cadmium salt and thiourea is 1:0.5-1:16, then ammonia water is added to adjust the pH of the mixed solution to 10-13, and finally the mixed solution is heated at 55-85°C for 1-5h. The obtained nanocatalyst can be applied to photocatalytic hydrogen production. The present invention uses cadmium salt as a raw material, synthesizes CdS / CdNCN nanocatalyst by a one-step oil bath, and the preparation method is simple and efficient. The obtained CdS / CdNCN nanocatalyst can significantly improve the efficiency of photocatalytic hydrogen production.

Description

Technical Field

[0001] The invention belongs to the field of photocatalytic materials, and in particular relates to a CdS / CdNCN nanocatalyst with a sheet-ball structure and a preparation method and application thereof. Background Art

[0002] The energy issue is the most important issue restricting the development of the world economy today.

[0003] Fossil energy utilization is characterized by high carbon, low efficiency and uncleanness, so many environmental problems caused by it are essentially energy problems. Clean, efficient and systematic application of clean energy, including solar energy, wind energy, hydropower, geothermal energy, biomass energy, tidal energy, etc., can achieve zero pollution or extremely low pollution to the ecological environment. Vigorously developing clean energy not only provides sufficient energy and guarantees the development of social economy, but also helps to improve the environment. Hydrogen energy is a secondary energy source with the advantages of cleanliness, pollution-free, high efficiency, light weight, good storage and transportation performance, and wide range of uses. However, hydrogen energy needs to be obtained from other energy sources in some way. The most convenient way is to electrolyze water. In addition, there are some biological hydrogen production methods that can be used to produce hydrogen. At present, the industrial hydrogen production method is mainly to produce hydrogen by reacting natural gas, oil and coal with water at high temperature. Although large-scale production has been achieved, it cannot meet the requirements of sustainable development. With the continuous development of science and technology, if low-cost hydrogen energy can be achieved, industrial large-scale production, and hydrogen energy as the main energy source can effectively improve environmental pollution and energy crisis. Among the many current hydrogen production methods, photolysis of water, as an emerging technology that uses solar energy to decompose water to obtain hydrogen, is a very promising method for hydrogen production.

[0004] CdS is a semiconductor with good photoresponse, with an appropriate band gap, responding to the wavelength of visible light, and can be used for photocatalytic hydrogen production. However, CdS also has some obvious disadvantages, especially in the process of photogenerated electron migration, it is easy to recombine with photogenerated holes, and the independent photocatalytic activity is not high. The H2 generation rate on pure CdS is very low, and CdS is not stable during the reaction process due to the accumulation of its own photogenerated holes, which is prone to photocorrosion.

[0005] Cadmium carbodiimide is a predicted and recently emerging material that is expected to be well utilized in energy, environment and other fields. The chemical formula of cadmium carbodiimide can be written as CdCN2 or CdNCN. As an organic group-metal complex, its unique two-dimensional structure reduces the transport free path of the carriers generated by the reaction, thereby reducing the recombination probability. Moreover, as an emerging material, there are many properties worth exploring. Summary of the invention

[0006] In view of the shortcomings and deficiencies of the above prior art, the primary purpose of the present invention is to provide a method for preparing a CdS / CdNCN nanocatalyst with a pellet structure.

[0007] Another object of the present invention is to provide a CdS / CdNCN nanocatalyst with a pellet structure prepared by the above method.

[0008] Another object of the present invention is to provide the application of the CdS / CdNCN nanocatalyst with a spherical structure in photocatalytic hydrogen production.

[0009] The purpose of the present invention is achieved through the following technical solutions:

[0010] A method for preparing a CdS / CdNCN nanocatalyst with a spherical structure comprises the following steps:

[0011] Cadmium salt and thiourea are added into water to obtain a mixed solution, wherein the molar ratio of the cadmium salt to thiourea is 1:0.5-1:16, and then ammonia water is added to adjust the pH of the mixed solution to 10-13, and finally the mixed solution is heated at 60-85°C for 1-5h, and then the solution is filtered to obtain the CdS / CdNCN nanocatalyst with a flake-spherical structure.

[0012] Preferably, the cadmium salt is Cd(NO3)2 and / or CdCl2.

[0013] Preferably, the heating temperature is 60° C. and the heating time is 3 hours.

[0014] Preferably, the mass volume ratio of the cadmium salt to water is 0.533 g: (70-100) mL.

[0015] A CdS / CdNCN nanocatalyst with a spherical structure is prepared by the method and is in the form of yellow powder.

[0016] Preferably, the particle size of the spherical CdS in the CdS / CdNCN nanocatalyst with a ball-shaped structure is 100-200 nm, and the total size of the balls is 1 μm-3 μm.

[0017] The CdS / CdNCN nanocatalyst with a spherical structure can be used in photocatalytic hydrogen production.

[0018] The present invention has the following advantages and beneficial effects:

[0019] (1) The present invention uses easily available, highly commercialized cadmium nitrate or cadmium chloride and thiourea as raw materials to synthesize CdS / CdNCN nanocatalysts by a one-step oil bath method. The operation is simple, the reaction time is short, and the synthesis efficiency is high. The obtained CdS / CdNCN nanocatalyst has a flake-spherical structure, high product purity, small spherical particle size, and good combination of CdS and CdNCN. The spherical diameter in the nanocatalyst is between 100 and 200 nm and is very uniformly distributed. The CC1-1 nanocatalyst prepared in Example 1 and the CC1-15 nanocatalyst prepared in Example 5 have specific surface areas of 25.1 m² / g and 23.4 m² / g, respectively.

[0020] (2) The CdS / CdNCN nanocatalyst prepared in the present invention has a flake-spherical structure, and the two constitute a suitable heterostructure, which promotes the separation of electron-hole pairs.

[0021] (3) The composite material prepared by the CdS / CdNCN nanocatalyst of the present invention can be used for photocatalytic hydrogen production. In a 0.25M Na2S / Na2SO3 solution, adding 10mg of CdS / CdNCN-1:1 nanocatalyst can produce 23514 μmol / g of hydrogen per hour. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 The SEM images of the CdS / CdNCN nanocatalysts obtained in Examples 1 to 5 of the present invention are shown.

[0023] Figure 2 The XRD diagrams of the CdS / CdNCN nanocatalysts obtained in Examples 1 to 5 of the present invention are shown.

[0024] Figure 3 It is the hydrogen production efficiency of the CdS / CdNCN nanocatalyst obtained in Examples 1 to 5 of the present invention.

[0025] Figure 4 The UV-visible absorption spectra of the CdS / CdNCN nanocatalysts obtained in Examples 1 to 5 of the present invention are shown.

[0026] In the above figures: 1:0.5 refers to the CC1-0.5 nanocatalyst prepared in Example 2, 1:1 refers to the CC1-1 nanocatalyst prepared in Example 1, 1:3 refers to the CC1-3 nanocatalyst prepared in Example 3, 1:6 refers to the CC1-6 nanocatalyst prepared in Example 4, and 1:15 refers to the CC1-15 nanocatalyst prepared in Example 5. DETAILED DESCRIPTION

[0027] The present invention is further described in detail below in conjunction with embodiments and drawings, but the embodiments of the present invention are not limited thereto.

[0028] Example 1

[0029] (1) Add 0.533 g of cadmium chloride powder to a beaker, add 0.23 g of thiourea, and then add 70 mL of deionized water, then add ammonia water to adjust the solution pH to 12, use a 60°C oil bath for 3 hours, and then filter the solution. The resulting yellow powder is the CdS / CdNCN nanocatalyst with a spherical structure. It is denoted as CC1-1 nanocatalyst. The scanning electron microscope (SEM) image of the obtained CC1-1 nanocatalyst is shown in the figure. Figure 1 As shown by Figure 1 It can be seen that the obtained CC1-1 nanocatalyst has a flake-spherical structure, with a sphere size of about 200nm and a flake size of about 3μm. The XRD pattern of the obtained CC1-1 nanocatalyst is shown in Figure 2 As shown, the XRD results show that the obtained yellow powder product is a high-purity CdS / CdNCN nanocatalyst.

[0030] The CC1-1 nanocatalyst prepared in this embodiment was used as a photocatalyst to carry out a photocatalytic hydrogen production test. 10 mg of photocatalyst was dispersed in 100 ml of an aqueous solution containing 0.25 M Na2S / Na2SO3, and 100 ml of the mixed solution was transferred to a quartz sealed reactor. A 300 W Xe lamp plus a filter was used to obtain a light source above 420 nm. Before illumination, N2 was introduced for more than 30 minutes to achieve an anaerobic environment in the reactor. After illumination, 400 μL of gas was extracted from the reactor every hour and analyzed by a gas chromatograph (GC-7900), and the photocatalytic hydrogen production efficiency was calculated. The hydrogen production efficiency of each gram of CC1-1 nanocatalyst was 23514 μmol / h. The comparison diagram of the hydrogen production efficiency of the obtained composite material with that of other embodiments is shown in the figure below. Figure 3 shown.

[0031] Example 2

[0032] (1) Add 0.533 g of cadmium chloride powder to a beaker, add 0.114 g of thiourea, and then add 80 mL of deionized water. Then add ammonia water to adjust the solution pH to 11. Incubate in an oil bath at 65°C for 3 hours. Then filter the solution. The resulting yellow powder is the CdS / CdNCN nanocatalyst with a spherical structure. It is referred to as CC1-0.5 nanocatalyst. The scanning electron microscope (SEM) image of the obtained CC1-0.5 nanocatalyst is shown in Figure 2. Figure 1 As shown by Figure 1 It can be seen that the obtained CC1-0.5 nanocatalyst has a flake-spherical structure, with a sphere size of about 200nm and a flake size of about 3μm. The XRD pattern of the obtained CC1-0.5 nanocatalyst is shown in Figure 2 As shown, the XRD results show that the obtained yellow powder product is a high-purity CC1-0.5 nanocatalyst.

[0033] The CC1-0.5 nanocatalyst prepared in this example was used as a photocatalyst to conduct a photocatalytic hydrogen production test. The hydrogen production efficiency of each gram of CC1-0.5 nanocatalyst was 11986 μmol / h. The comparison of the hydrogen production efficiency of the composite material is shown in the figure below. Figure 3 shown.

[0034] Example 3

[0035] (1) Add 0.533 g of cadmium chloride powder to a beaker, add 0.69 g of thiourea, and then add 90 mL of deionized water. Then add ammonia water to adjust the pH of the solution to 11. Incubate in an oil bath at 60°C for 3 hours. Then filter the solution. The resulting yellow powder is the CdS / CdNCN nanocatalyst with a spherical structure. It is referred to as CC1-3 nanocatalyst. The scanning electron microscope (SEM) image of the obtained CC1-3 nanocatalyst is shown in Figure 2. Figure 1 As shown by Figure 1 It can be seen that the obtained CC1-3 nanocatalyst has a flake-spherical structure, with a sphere size of about 200nm and a flake size of about 3μm. The XRD pattern of the obtained CC1-3 nanocatalyst is shown in Figure 2 As shown, the XRD results show that the obtained yellow powder product is a high-purity CC1-3 nanocatalyst.

[0036] The CC1-3 nanocatalyst prepared in this example was used as a photocatalyst to conduct a photocatalytic hydrogen production test. The hydrogen production efficiency of each gram of CC1-3 nanocatalyst was 3998 μmol / h. The comparison of the hydrogen production efficiency of the composite material is shown in the figure below. Figure 3 shown.

[0037] Example 4

[0038] (1) Add 1.38 g of thiourea to 0.533 g of cadmium chloride powder in a beaker, then add 100 mL of deionized water, then add ammonia water to adjust the pH of the solution to 11, and place in an oil bath at 85°C for 3 hours. Then filter the solution. The resulting yellow powder is the CdS / CdNCN nanocatalyst with a spherical structure. It is denoted as CC1-6 nanocatalyst. The scanning electron microscope (SEM) image of the obtained CC1-6 nanocatalyst is shown in the figure. Figure 1 As shown by Figure 1 It can be seen that the obtained CC1-6 nanocatalyst has a flake-spherical structure, with a sphere size of about 200nm and a flake size of about 3μm. The XRD pattern of the obtained CC1-15 nanocatalyst is shown in Figure 2 As shown, the XRD results show that the obtained yellow powder product is a high-purity CC1-15 nanocatalyst.

[0039] The CC1-6 nanocatalyst prepared in this example was used as a photocatalyst to conduct a photocatalytic hydrogen production test. The hydrogen production efficiency of each gram of CC1-6 nanocatalyst was 2750 μmol / h. The comparison of the hydrogen production efficiency of the composite material is shown in the figure below. Figure 3 shown.

[0040] Example 5

[0041] (1) Add 3.45 g of thiourea to 0.533 g of cadmium chloride powder in a beaker, then add 100 mL of deionized water, then add ammonia water to adjust the pH of the solution to 12, and place in an oil bath at 65°C for 3 hours. Then filter the solution. The resulting yellow powder is the CdS / CdNCN nanocatalyst with a spherical structure. It is denoted as CC1-15 nanocatalyst. The scanning electron microscope (SEM) image of the obtained CC1-15 nanocatalyst is shown in the figure below. Figure 1 As shown by Figure 1 It can be seen that the obtained CC1-15 nanocatalyst has a global structure, and the sphere size is about 500nm. The XRD pattern of the obtained CC1-15 nanocatalyst is as follows Figure 2 As shown, the XRD results show that the obtained yellow powder product is a high-purity CC1-15 nanocatalyst.

[0042] The CC1-15 nanocatalyst prepared in this example was used as a photocatalyst to conduct a photocatalytic hydrogen production test. The hydrogen production efficiency of each gram of CC1-15 nanocatalyst was 2750 μmol / h. The comparison of the hydrogen production efficiency of the composite material is shown in the figure below. Figure 3 shown.

[0043] The above embodiments are preferred implementation modes of the present invention, but the implementation modes of the present invention are not limited to the above embodiments. Any other changes, modifications, substitutions, combinations, and simplifications that do not deviate from the spirit and principles of the present invention should be equivalent replacement methods and are included in the protection scope of the present invention.

Claims

1. A method for preparing a CdS / CdNCN nanocatalyst with a spherical structure, characterized in that: The steps include: Cadmium salt and thiourea are added into water to obtain a mixed solution, wherein the molar ratio of the cadmium salt to the thiourea is 1:0.5-1:16, and then ammonia water is added to adjust the pH of the mixed solution to 10-13, and finally the mixed solution is heated at 55-85°C for 1-5 hours, and then the solution is filtered to obtain a CdS / CdNCN nanocatalyst with a flake-spherical structure; the mass volume ratio of the cadmium salt to water is 0.533g: (70-100)mL; and the cadmium salt is Cd(NO3)2 and / or CdCl2.

2. The preparation method according to claim 1, characterized in that: The heating temperature is 60° C. and the heating time is 3 h.

3. A CdS / CdNCN nanocatalyst with a spherical structure, characterized in that: It is prepared by the method according to claim 1 or 2.

4. The CdS / CdNCN nanocatalyst according to claim 3, characterized in that: The CdS / CdNCN nano catalyst is in the form of yellow powder.

5. The CdS / CdNCN nanocatalyst according to claim 3, characterized in that: The particle size of the spherical CdS in the CdS / CdNCN nanocatalyst is 100-200nm, and the total size of the spheres is 1μm-3μm.

6. Use of the CdS / CdNCN nanocatalyst according to any one of claims 3 to 5 in photocatalytic hydrogen production.

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