A CS-HS / HCds photocatalyst with a composite structure and its preparation method and application

Abstract

The present invention relates to the field of photocatalytic hydrolysis technology, and in particular to a composite structure CS-HS / HCDS photocatalyst, its preparation method, and application. The present invention provides a composite structure CS-HS / HCDS photocatalyst, comprising hexagonal cadmium sulfide, cadmium sulfide nanoparticles with a cubic crystal structure, and cadmium sulfide nanoparticles with a hexagonal crystal structure; the cadmium sulfide nanoparticles with a cubic crystal structure, the cadmium sulfide nanoparticles with a hexagonal crystal structure, and the hexagonal cadmium sulfide form a structure with a gradient charge transfer chain. During the photocatalytic process, photogenerated electrons can also be sequentially transferred from h-CdS to h S ‑CdS, c S This gradient charge transfer chain structure greatly promotes the separation of photogenerated electrons and holes, thereby improving the c S ‑h S / h Photocatalytic activity of CdS photocatalyst.

Description

Technical Field

[0001] The present invention relates to the technical field of photocatalytic hydrolysis, and in particular to a CS-HS / HCDS photocatalyst with a composite structure, a preparation method and an application thereof. Background Art

[0002] With the growing global demand for renewable energy, photocatalytic technology utilizing solar energy has become a research hotspot in the renewable energy field. Solar energy is one of the most abundant and clean energy sources. Decomposing water into hydrogen and oxygen through solar photocatalysis not only reduces fossil fuel use but also improves energy security. Therefore, the development of new clean energy technologies using solar photocatalytic water decomposition to produce hydrogen has attracted considerable attention from researchers both domestically and internationally.

[0003] Cadmium sulfide (CdS) photocatalyst, with a band gap of 2.4 eV, can effectively utilize visible light and is widely used in visible light photocatalytic water decomposition to produce hydrogen. However, the photogenerated charges of CdS are very easy to recombine, which greatly limits its photocatalytic activity. Summary of the Invention

[0004] The object of the present invention is to provide a CS-HS / H Cds photocatalyst with a composite structure, a preparation method and an application thereof, wherein the CS-HS / H Cds photocatalyst with a composite structure has high photocatalytic activity.

[0005] In order to achieve the above-mentioned object of the invention, the present invention provides the following technical solutions:

[0006] The present invention provides a CS-HS / hCds photocatalyst with a composite structure, comprising hexagonal cadmium sulfide, cadmium sulfide nanoparticles with a cubic crystal form, and cadmium sulfide nanoparticles with a hexagonal crystal form;

[0007] A structure with a gradient charge transfer chain is formed between the cubic cadmium sulfide nanoparticles, the hexagonal cadmium sulfide nanoparticles and the hexagonal cadmium sulfide.

[0008] Preferably, the mass ratio of the hexagonal cadmium sulfide, the cadmium sulfide nanoparticles having a cubic crystal structure, and the cadmium sulfide nanoparticles having a hexagonal crystal structure is (32-35): (9-15): (0.5-5).

[0009] The present invention also provides a method for preparing the composite structure CS-HS / HCds photocatalyst described in the above technical solution, comprising the following steps:

[0010] After mixing a cadmium source, ethylenediamine and an alkaline solution, thioacetamide is added and a hydrothermal reaction is performed to obtain a mixture; the mixture includes cadmium sulfide nanoparticles having a cubic crystal structure and cadmium sulfide nanoparticles having a hexagonal crystal structure;

[0011] The mixture is calcined to obtain the cs-hs / hCds photocatalyst with a composite structure.

[0012] Preferably, the alkali solution is a sodium hydroxide solution with a concentration of 10 to 15 mol / L.

[0013] Preferably, the usage ratio of the cadmium source and the alkali solution is (1-5) mmol: (30-80) mL;

[0014] The usage ratio of the cadmium source and ethylenediamine is (1-5) mmol: (5-15) mL;

[0015] The usage of the cadmium source and thioacetamide is (1-5) mmol: (0.1-0.3) g.

[0016] Preferably, the temperature of the hydrothermal reaction is 140-240° C., and the time is 12-72 hours.

[0017] Preferably, after the hydrothermal reaction is completed, solid-liquid separation, washing and drying are further performed in sequence.

[0018] Preferably, the calcination temperature is 50-350° C., and the holding time is 0.5-6 h.

[0019] The present invention also provides the use of the CS-HS / H Cds photocatalyst with a composite structure described in the above technical solution or the CS-HS / H Cds photocatalyst with a composite structure prepared by the preparation method described in the above technical solution in photocatalytic hydrolysis to produce hydrogen.

[0020] Preferably, the application method comprises:

[0021] After loading metal Pt on the composite structure cs-hs / h Cds photocatalyst, it was mixed with water containing a hole sacrificial agent and photolyzed under light conditions.

[0022] The CS-HS / H Cds photocatalyst with a composite structure is the CS-HS / H Cds photocatalyst with a composite structure described in the above technical solution or the CS-HS / H Cds photocatalyst with a composite structure prepared by the preparation method described in the above technical solution.

[0023] The present invention provides a composite structure CS-HS / hCds photocatalyst, comprising hexagonal cadmium sulfide, cadmium sulfide nanoparticles with a cubic crystal structure, and cadmium sulfide nanoparticles with a hexagonal crystal structure; a structure having a gradient charge transfer chain is formed between the cadmium sulfide nanoparticles with a cubic crystal structure, the cadmium sulfide nanoparticles with a hexagonal crystal structure, and the hexagonal cadmium sulfide. In the composite structure CS-HS / hCds photocatalyst provided by the present invention, the cadmium sulfide nanoparticles with a cubic crystal structure (cds) are present in the cadmium sulfide nanoparticles with a cubic crystal structure, and the cadmium sulfide nanoparticles with a hexagonal crystal structure are present in the cadmium sulfide nanoparticles with a cubic crystal structure. S -CdS) and cadmium sulfide nanoparticles with hexagonal structure (h S -CdS), hexagonal cadmium sulfide (h-CdS) suitable valence band and conduction band position, can form a charge transfer chain, the formation of the charge transfer chain can make c S -The holes formed in CdS are transferred to h S -CdS, h-CdS, thereby promoting the transfer of holes. At the same time, photogenerated electrons can also be transferred from h-CdS to h S -CdS, c S -CdS, promoting the transfer of electrons. This gradient charge transfer chain structure greatly promotes the separation of photogenerated electrons and holes, thereby improving c S -h S / h CdS photocatalytic activity. According to the examples, the rate of photocatalytic decomposition of water to produce hydrogen by the composite structure cs-hs / h Cds photocatalyst provided by the present invention is relatively high. S -CdS increased by 3.6 times BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 100-c as described in Example 1 S -h S / h CdS, Comparative Example 1 S / h CdS and the c S - XRD pattern of CdS;

[0025] Figure 2 100-c as described in Example 2 S -h S / h CdS (1), 300-c described in Example 3 S -h S / h CdS (1) and the comparative example 3 S -XRD pattern of CdS(1);

[0026] Figure 3 100-c as described in Example 1 S -h S / h CdS, Comparative Example 1 S / h CdS and the c S -Hydrogen production rate bar graph of CdS after 2h photocatalytic decomposition;

[0027] Figure 4 100-c as described in Example 2 S -h S / h CdS (1), 300-c described in Example 3 S -h S / h CdS (1) and the comparative example 3 S -Bar chart of the hydrogen production rate of CdS(1) after 2h of photocatalytic hydrolysis. DETAILED DESCRIPTION

[0028] The present invention provides a CS-HS / HCds photocatalyst with a composite structure, comprising hexagonal cadmium sulfide, cadmium sulfide nanoparticles with a cubic crystal form, and cadmium sulfide nanoparticles with a hexagonal crystal form;

[0029] A structure with a gradient charge transfer chain is formed between the cubic cadmium sulfide nanoparticles, the hexagonal cadmium sulfide nanoparticles and the hexagonal cadmium sulfide.

[0030] In the present invention, a heterogeneous junction is formed between the cadmium sulfide nanoparticles having a cubic crystal structure and the cadmium sulfide nanoparticles having a hexagonal crystal structure.

[0031] In the present invention, the mass ratio of the hexagonal cadmium sulfide, the cubic cadmium sulfide nanoparticles and the hexagonal cadmium sulfide nanoparticles is preferably (32-35): (9-15): (0.5-5), more preferably (34-35): (12-15): (1-3), and most preferably 35: (13-14): (1-2).

[0032] The present invention also provides a method for preparing the composite structure CS-HS / HCds photocatalyst described in the above technical solution, comprising the following steps:

[0033] After mixing a cadmium source, ethylenediamine and an alkaline solution, thioacetamide is added and a hydrothermal reaction is performed to obtain a mixture; the mixture includes cadmium sulfide nanoparticles having a cubic crystal structure and cadmium sulfide nanoparticles having a hexagonal crystal structure;

[0034] The mixture is calcined to obtain the cs-hs / h Cds photocatalyst with a composite structure.

[0035] In the present invention, unless otherwise specified, all preparation raw materials are commercially available products well known to those skilled in the art.

[0036] The invention mixes a cadmium source, ethylenediamine and an alkaline solution, adds thioacetamide, and performs a hydrothermal reaction to obtain a mixture; the mixture comprises cadmium sulfide nanoparticles with a cubic crystal form and cadmium sulfide nanoparticles with a hexagonal crystal form.

[0037] In the present invention, the cadmium source preferably includes cadmium nitrate tetrahydrate and / or cadmium acetate dihydrate; when the cadmium source includes cadmium nitrate tetrahydrate and cadmium acetate dihydrate, the present invention has no special limitation on the ratio of the cadmium nitrate tetrahydrate and cadmium acetate dihydrate, and they can be mixed in any ratio.

[0038] In the present invention, the alkali solution is preferably a sodium hydroxide solution with a concentration of 10 to 15 mol / L, more preferably a sodium hydroxide solution with a concentration of 11 to 12 mol / L. In the present invention, the sodium hydroxide solution with the above concentration can be more conducive to the full dissolution of the cadmium source, thereby enabling a more complete reaction in the subsequent reaction.

[0039] In the present invention, the usage ratio of the cadmium source and the alkali solution is preferably (1-5) mmol: (30-80) mL, more preferably (1.5-3) mmol: (40-70) mL, and most preferably (2.5-3) mmol: (50-60) mL.

[0040] In the present invention, the usage ratio of the cadmium source and ethylenediamine is preferably (1-5) mmol: (5-15) mL, more preferably (1.5-3) mmol: (8-11) mL, and most preferably (2.5-3) mmol: (8-10) mL.

[0041] In the present invention, controlling the amounts of the cadmium source, alkali solution and ethylenediamine within the above ranges is more conducive to obtaining a mixture of cubic cadmium sulfide nanoparticles and hexagonal cadmium sulfide nanoparticles.

[0042] The present invention does not impose any particular restrictions on the order of mixing, and any order familiar to those skilled in the art may be employed. In the present invention, the mixing is preferably performed under stirring; the stirring time is preferably 20 to 100 minutes, more preferably 30 to 60 minutes. The present invention does not impose any particular restrictions on the stirring speed, and any speed familiar to those skilled in the art may be employed to ensure that the cadmium source, alkali solution, and ethylenediamine are fully mixed within the aforementioned time range.

[0043] In the present invention, the role of the alkali solution is to provide a strong alkaline environment, which is conducive to the dissolution of cadmium acetate and promotes the growth of cadmium sulfide crystals. The role of the ethylenediamine is to act as a coordination agent to promote the formation of cadmium sulfide.

[0044] In the present invention, the amount of the cadmium source and thioacetamide is preferably (1-5) mmol: (0.1-0.3) g, more preferably (1.5-3) mmol: (0.15-0.25) g, and most preferably (2.5-3) mmol: (0.18-0.22) g.

[0045] The present invention does not have any special limitation on the manner of adding the thioacetamide, and any manner well known to those skilled in the art can be used.

[0046] After the addition of thioacetamide is completed, the present invention further preferably includes stirring, and the stirring time is preferably 1 to 4 hours, more preferably 1.5 to 3 hours. In the present invention, the stirring process is more conducive to the full dissolution of thioacetamide, thereby enabling a more complete reaction in the subsequent hydrothermal reaction.

[0047] In the present invention, the temperature of the hydrothermal reaction is preferably 140-240°C, more preferably 160-200°C, and most preferably 170-180°C; the time is preferably 12-72 hours, more preferably 12-32 hours, and most preferably 16-28 hours. In the present invention, controlling the conditions of the hydrothermal reaction within the above ranges can be more conducive to fully generating a mixture of cadmium sulfide nanoparticles having a cubic crystal structure and cadmium sulfide nanoparticles having a hexagonal crystal structure.

[0048] After the hydrothermal reaction is completed, the present invention preferably further comprises sequentially performing solid-liquid separation, washing and drying.

[0049] In the present invention, the solid-liquid separation method is preferably centrifugation, and the centrifugal speed is preferably 5000-9000 r / min, more preferably 6000-8000 r / min, and most preferably 6500-7500 r / min; the centrifugal time is preferably 1-5 min / time, more preferably 2-4 min / time.

[0050] In the present invention, the washing is preferably an alcohol wash and a water wash performed sequentially; the alcohol wash is preferably an ethanol wash. The present invention does not particularly limit the specific process of the alcohol wash and the water wash, and can be performed using a process well known to those skilled in the art. In the present invention, washing with water first and then with alcohol is beneficial for fully removing impurities from the mixture of cubic cadmium sulfide nanoparticles and hexagonal cadmium sulfide nanoparticles.

[0051] In the present invention, the drying temperature is preferably 80° C.; the drying method is preferably vacuum drying and / or air atmosphere drying.

[0052] After obtaining the mixture, the present invention performs a calcination treatment on the mixture to obtain the cs-hs / h Cds photocatalyst with a composite structure.

[0053] In the present invention, the temperature of the calcination treatment is preferably 50 to 350°C, more preferably 100 to 250°C; the holding time is preferably 0.5 to 6 hours, more preferably 1 to 3 hours. The present invention controls the calcination treatment under the above conditions, which is more conducive to the preparation of the photocatalyst of the present invention. The present invention uses the calcination treatment to make the c S -CdS is partially converted into h S -CdS, thus forming a cadmium sulfide photocatalyst with a gradient charge transfer chain structure (c S -h S / h-CdS).

[0054] The present invention also provides the use of the CS-HS / H Cds photocatalyst with a composite structure described in the above technical solution or the CS-HS / H Cds photocatalyst with a composite structure prepared by the preparation method described in the above technical solution in photocatalytic hydrolysis to produce hydrogen.

[0055] In the present invention, the method of application preferably includes:

[0056] After loading metal Pt on the composite structure cs-hs / h Cds photocatalyst, it was mixed with water containing a hole sacrificial agent and photolyzed under light conditions.

[0057] The CS-HS / H Cds photocatalyst with a composite structure is the photocatalyst described in the above technical solution or the CS-HS / H Cds photocatalyst with a composite structure prepared by the preparation method described in the above technical solution.

[0058] In the present invention, the loading amount of Pt in the cs-hs / hCds photocatalyst having a composite structure is preferably 1.0 wt %.

[0059] In the present invention, the usage ratio of the composite structure cs-hs / h Cds photocatalyst and the water containing the hole sacrificial agent is preferably (0.05-0.2) g: (80-120) mL, more preferably 0.1 g: (90-110) mL.

[0060] In the present invention, the hole sacrificial agent in the water containing the hole sacrificial agent is preferably sodium sulfite and sodium sulfide nonahydrate; the concentration of sodium sulfite in the water containing the hole sacrificial agent is preferably 0.1 to 0.4 mol / L, more preferably 0.2 to 0.3 mol / L; the concentration of sodium sulfide nonahydrate in the water containing the hole sacrificial agent is preferably 0.2 to 0.5 mol / L, more preferably 0.3 to 0.4 mol / L.

[0061] The present invention does not have any special limitation on the mixing process, and the mixing process may be carried out using a process well known to those skilled in the art.

[0062] In the present invention, the irradiation is preferably performed under the irradiation of a xenon lamp.

[0063] The following is a detailed description of the composite structure CS-HS / HCds photocatalyst provided by the present invention, its preparation method and application, in conjunction with the examples. However, they should not be construed as limiting the scope of protection of the present invention.

[0064] Example 1

[0065] 2mmol of cadmium acetate dihydrate and 50mL of 12mol / L sodium hydroxide solution were mixed and stirred until the cadmium acetate dihydrate was completely dissolved, 10mL of ethylenediamine was added and stirred for 30min, 2.5mmol of thioacetamide was added and stirred for 2.5h, and the obtained mixture was poured into a reactor for hydrothermal reaction (the temperature of the hydrothermal reaction was 200℃ and the time was 24h. After the hydrothermal reaction was completed, the mixture was centrifuged (the speed was 9000r and the time was 2min), and the ethanol washing and water washing were repeated three times in sequence, and the mixture was vacuum dried at 80℃ for 12h to obtain a mixture of cadmium sulfide nanoparticles having cubic crystal form and cadmium sulfide nanoparticles having hexagonal crystal form (c S / h CdS);

[0066] The mixture was calcined (100°C, 2h) to obtain a composite structure of cs-hs / h Cds photocatalyst (denoted as 100-c S -h S / h CdS).

[0067] Comparative Example 1

[0068] Referring to Example 1, c S / h CdS.

[0069] Comparative Example 2

[0070] 2mmol of cadmium acetate dihydrate and 50mL of 12mol / L sodium hydroxide solution were mixed and stirred until the cadmium acetate dihydrate was completely dissolved, 10mL of ethylenediamine was added and stirred for 30min, 2.5mmol of thioacetamide was added and stirred for 2.5h, and the obtained mixture was poured into a reactor for hydrothermal reaction (the temperature of the hydrothermal reaction was 150℃ and the time was 24h. After the hydrothermal reaction was completed, centrifugation was performed (the speed was 9000r and the time was 2min), and ethanol washing and water washing were repeated three times in sequence, and vacuum drying was performed at 80℃ for 12h to obtain c S -CdS.

[0071] Figure 1 100-c as described in Example 1 S -h S / h CdS, Comparative Example 1 S / h CdS and the c S -XRD pattern of CdS, by Figure 1 It can be seen that the diffraction peaks belonging to hexagonal cadmium sulfide are observed at 2θ=24.8°, 26.5°, and 28.2°. The diffraction peaks belonging to cubic cadmium sulfide are observed at 2θ=30.6°, 54.5°, and 63.8°. S / h CdS Diffraction peaks belonging to hexagonal cadmium sulfide were observed at 2θ=24.8°, 26.5°, and 28.2°. Diffraction peaks belonging to cubic cadmium sulfide were observed at 2θ=30.6°, 54.5°, and 63.8°. This indicates that a CdS containing S -CdS, h-CdS composite materials, and successfully synthesized c S / hCdS photocatalyst. ; For 100-c S -h S / h CdS observed diffraction peaks belonging to hexagonal cadmium sulfide at 2θ=24.8°, 26.5°, and 28.2°. Diffraction peaks belonging to cubic cadmium sulfide were observed at 2θ=30.6°, 54.5°, and 63.8°. Compared with cs / h CdS, it can be seen that 100-c S -h S / h CdS, the peak intensity corresponding to hexagonal cadmium sulfide increases significantly, indicating that the proportion of hexagonal cadmium sulfide increases, further indicating that part of cubic cadmium sulfide is converted into hexagonal cadmium sulfide. This shows that a phase containing c S -CdS, h S -CdS, h-CdS composite materials, and successfully synthesized 100-c with a charge transfer chain structure S -h S / h CdS photocatalyst.

[0072] Example 2

[0073] 2mmol of cadmium acetate dihydrate and 50mL of 12mol / L sodium hydroxide solution were mixed and stirred until the cadmium acetate dihydrate was completely dissolved, 10mL of ethylenediamine was added and stirred for 30min, 2.5mmol of thioacetamide was added and stirred for 2h, and the obtained mixture was poured into a reactor for hydrothermal reaction (the temperature of the hydrothermal reaction was 200℃ and the time was 24h. After the hydrothermal reaction was completed, the mixture was centrifuged (the speed was 9000r and the time was 2min), and the ethanol washing and water washing were repeated three times in sequence, and the mixture was vacuum dried at 80℃ for 12h to obtain a mixture of cadmium sulfide nanoparticles having cubic crystal form and cadmium sulfide nanoparticles having hexagonal crystal form (c S / h CdS(1));

[0074] The mixture was calcined (200°C, 2h) to obtain a composite structure of cs-hs / h Cds photocatalyst (denoted as 200-c S -h S / h CdS(1)).

[0075] Example 3

[0076] Referring to Example 2, the difference is that the calcination temperature is 300°C, and a composite structure cs-hs / h Cds photocatalyst (denoted as 300-c S -h S / h CdS(1)).

[0077] Comparative Example 3

[0078] 2.5mmol of cadmium acetate dihydrate and 50mL of 12mol / L sodium hydroxide solution were mixed and stirred until the cadmium acetate dihydrate was completely dissolved, 10mL of ethylenediamine was added and stirred for 30min, 2.5mmol of thioacetamide was added and stirred for 2h, and the obtained mixture was poured into a reactor for hydrothermal reaction (the temperature of the hydrothermal reaction was 90°C and the time was 24h. After the hydrothermal reaction was completed, centrifugation was performed (the speed was 9000r and the time was 2min), and ethanol washing and water washing were repeated three times in sequence, and vacuum drying was performed at 80°C for 12h to obtain c S -CdS(1)).

[0079] Figure 2 200-c as described in Example 2 S -h S / h CdS (1), 300-c described in Example 3 S -h S / h CdS (1) and the comparative example 3 S -CdS(1) XRD pattern, Figure 2 It can be seen that the diffraction peaks belonging to hexagonal cadmium sulfide are observed at 2θ=24.8°, 26.5°, and 28.2°. The diffraction peaks belonging to cubic cadmium sulfide are observed at 2θ=30.6°, 54.5°, and 63.8°. S -h S / h CdS(1) and 300-c S -h S / h CdS(1) diffraction peaks belonging to hexagonal cadmium sulfide were observed at 2θ=24.8°, 26.5°, and 28.2°. Diffraction peaks belonging to cubic cadmium sulfide were observed at 2θ=30.6°, 54.5°, and 63.8°. S -h S / h CdS(1) and 300-ch S / h CdS(1) contains c-CdS, h S -CdS, h-CdS.

[0080] Application Example 1

[0081] The photocatalytic activity of the photocatalysts obtained in Examples 1 to 2 and Comparative Examples 1 to 4 was tested. 1.0 wt% of Pt was loaded by the photodeposition method. Photocatalytic water decomposition was used as a model reaction, and a 300W xenon lamp light source was suspended above a reactor with a volume of 250 mL. 3.2 g of sodium sulfite, 8.4 g of sodium sulfide nonahydrate, 100 mL of water and 0.1 g of a Pt-loaded photocatalyst were added to the reactor and stirred to form a suspension system. The photocatalytic water decomposition reaction was carried out under the irradiation of a 300W xenon lamp light source. Before turning on the light, the reactor was vacuumed. The timing started from turning on the light. After 30 minutes of illumination, the gas in the reaction system was quantitatively taken out and loaded into a gas chromatograph with Ar as the carrier gas for quantitative analysis. The entire test of photocatalytic water decomposition for hydrogen production lasted for 2 hours, with samples taken at intervals of 30 minutes. The volume of hydrogen produced by the photocatalytic water decomposition was determined by the external standard method, and then the hydrogen production rate of the catalyst photocatalytic water decomposition was calculated. The photocatalytic hydrogen production rate v can be calculated by the following formula:

[0082]

[0083] Wherein, A is the total amount of hydrogen produced during the reaction time, unit: mL; t is the total reaction time, unit: h.

[0084] The test results are shown in Table 1 and Figures 3-4 As shown:

[0085] Table 1 The photocatalytic decomposition of water and hydrogen production rate of the photocatalysts in Examples 1 to 2 and Comparative Examples 1 to 4 after 2 hours

[0086] Types of photocatalysts Photocatalytic decomposition of water to produce hydrogen (μmol / h) Example 1 1497 Comparative Example 1 1008 Comparative Example 2 403 Example 2 1397 Example 3 532 Comparative Example 3 423

[0087] As can be seen from Table 1, the 100-c S -h S / h CdS photocatalyst can effectively improve the rate of hydrogen production from photocatalytic water decomposition. After 2h of illumination, 100-c S -h S / h The hydrogen production rate of CdS is higher than that of c S / h CdS、c S -CdS. It can be seen that this 100-c with a gradient charge transfer chain structure S -h S / h CdS photocatalytic activity is higher than that of heterojunction structure S / h-CdS, Description 00-c S -h S / h CdS can improve the catalytic activity of photocatalysts. In order to more clearly compare the effects of different photocatalysts on the production of hydrogen from water, the rates of photocatalytic water production from different photocatalysts are plotted as a bar graph, as shown in the figure below. Figure 3 It can be clearly seen that the 100-c S -h S / h CdS photocatalytic decomposition of water to produce hydrogen is more effective than c S / h CdS、c S -CdS sample; 200-c S -h S / h The hydrogen production rate of CdS(1) is higher than that of c S -CdS(1) and 300-c S -h S / h CdS(1). In order to more clearly compare the effects of different photocatalysts on the production of hydrogen from water, the rates of photocatalytic water production from different photocatalysts are plotted as a bar graph, as shown in Figure 4 As shown. It can be clearly seen that the 200-c S -h S / h CdS(1) photocatalytic decomposition of water to produce hydrogen is higher than c S -CdS(1) and 300-c S -h S / h CdS(1) sample.

[0088] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principles of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A composite structure cs-hs / h Cds photocatalyst, characterized in that: The invention comprises hexagonal cadmium sulfide, cadmium sulfide nanoparticles with cubic crystal structure and cadmium sulfide nanoparticles with hexagonal crystal structure; A structure having a gradient charge transfer chain is formed between the cubic cadmium sulfide nanoparticles, the hexagonal cadmium sulfide nanoparticles and the hexagonal cadmium sulfide; The preparation method of the composite structure CS-HS / hCds photocatalyst comprises the following steps: After mixing a cadmium source, ethylenediamine and an alkaline solution, thioacetamide is added and a hydrothermal reaction is performed to obtain a mixture; the mixture includes cadmium sulfide nanoparticles having a cubic crystal structure and cadmium sulfide nanoparticles having a hexagonal crystal structure; calcining the mixture to obtain the cs-hs / h Cds photocatalyst having a composite structure; The calcination temperature is 100-300°C and the holding time is 2h; The alkali solution is a sodium hydroxide solution with a concentration of 10 to 15 mol / L; The usage ratio of the cadmium source and the alkali solution is (1-5) mmol: (30-80) mL; The usage ratio of the cadmium source and ethylenediamine is (1-5) mmol: (5-15) mL; The amount of the cadmium source and thioacetamide is (1-5) mmol: (0.1-0.3) g; The temperature of the hydrothermal reaction is 200° C. and the time is 24 hours.

2. The cs-hs / h Cds photocatalyst with a composite structure according to claim 1, characterized in that: The mass ratio of the hexagonal cadmium sulfide, the cubic cadmium sulfide nanoparticles and the hexagonal cadmium sulfide nanoparticles is (32-35): (9-15): (0.5-5).

3. The method for preparing the composite structure CS-HS / HCds photocatalyst according to claim 1 or 2, characterized in that: The following steps are involved: After mixing a cadmium source, ethylenediamine and an alkaline solution, thioacetamide is added and a hydrothermal reaction is performed to obtain a mixture; the mixture includes cadmium sulfide nanoparticles having a cubic crystal structure and cadmium sulfide nanoparticles having a hexagonal crystal structure; calcining the mixture to obtain the cs-hs / h Cds photocatalyst having a composite structure; The calcination temperature is 100-300°C and the holding time is 2h; The alkali solution is a sodium hydroxide solution with a concentration of 10 to 15 mol / L; The usage ratio of the cadmium source and the alkali solution is (1-5) mmol: (30-80) mL; The usage ratio of the cadmium source and ethylenediamine is (1-5) mmol: (5-15) mL; The amount of the cadmium source and thioacetamide is (1-5) mmol: (0.1-0.3) g; The temperature of the hydrothermal reaction is 200° C. and the time is 24 hours.

4. The preparation method according to claim 3, wherein After the hydrothermal reaction is completed, solid-liquid separation, washing and drying are carried out in sequence.

5. Use of the composite structure CS-HS / h Cds photocatalyst according to claim 1 or 2 or the composite structure CS-HS / h Cds photocatalyst prepared by the preparation method according to claim 3 or 4 in photocatalytic hydrolysis to produce hydrogen.

6. The use according to claim 5, characterized in that The method of application includes: After loading metal platinum on the composite structure cs-hs / h Cds photocatalyst, it was mixed with water containing a hole sacrificial agent and photolyzed under light conditions. The composite structured cs-hs / h Cds photocatalyst is the composite structured cs-hs / h Cds photocatalyst according to claim 1 or 2 or the composite structured cs-hs / h Cds photocatalyst prepared by the preparation method according to claim 3 or 4.

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