Bimetallic sulfide modified cadmium selenide photocatalyst, method for preparing same, and use thereof

Abstract

The application provides a bimetallic sulfide modified cadmium selenide photocatalyst and a preparation method and application thereof, and belongs to the technical field of photocatalytic hydrogen production. The application prepares cadmium selenide / copper molybdenum sulfide by hydrothermal reaction of copper molybdenum sulfide and cadmium selenide. The application successfully prepares cadmium selenide / copper molybdenum sulfide (CdSe / Cu2MoS4) with high purity and good crystallization by adopting a solvothermal synthesis method (hydrothermal reaction); the cadmium selenide (CdSe) is successfully modified by a method of constructing a heterojunction, and the photocatalytic hydrogen production performance is greatly improved, a new path is provided for modifying existing photocatalysts, and new impetus is injected into the development of photocatalytic hydrogen production technology.

Description

Technical Field

[0001] This invention relates to the field of photocatalytic hydrogen production technology, and in particular to a method for modifying cadmium selenide photocatalysts with bimetallic sulfides, the bimetallic sulfide-modified cadmium selenide photocatalysts prepared by the method, and the application of the bimetallic sulfide-modified cadmium selenide photocatalysts in photocatalytic hydrogen production. Background Technology

[0002] The depletion of fossil fuels and environmental pollution have become major challenges restricting the sustainable development of human society. Converting solar energy into clean hydrogen energy offers a promising technological path to address this global issue. Among these technologies, photocatalytic water splitting for hydrogen production is considered an important direction for achieving efficient hydrogen production due to its environmentally friendly characteristics. Over the past fifty years, the scientific community has developed various photocatalytic material systems. However, current research generally indicates that catalysts still face key technical bottlenecks such as low solar energy conversion efficiency, excessively rapid recombination rates of photogenerated carriers limiting effective catalytic reactions, and insufficient photochemical stability. Although noble metal-supported modification technology can partially alleviate these problems, its high cost due to resource scarcity severely restricts its potential for large-scale application. Developing novel photocatalytic systems that combine high efficiency, stability, and economy to achieve a substantial breakthrough in hydrogen production efficiency has become a common goal for researchers in this field.

[0003] From the perspective of heterogeneous catalysis mechanism, the photocatalytic reaction process mainly includes the following three stages:

[0004] (1) Light absorption and electronic excitation: Semiconductor materials absorb photons under light conditions, which causes valence band electrons to undergo interband transitions and form electron-hole pairs (i.e., photogenerated carriers).

[0005] (2) Carrier dynamics: Photogenerated carriers generated by stimulation have two decay pathways during migration: bulk recombination and surface recombination. Among them, recombination, which dissipates energy in the form of thermodynamics or radiation, cannot contribute to the catalytic reaction process, while carriers that are successfully separated and migrated to the catalyst surface participate in subsequent redox reactions.

[0006] (3) Surface redox reaction: Photogenerated electrons and holes that migrate to the catalyst surface participate in reduction and oxidation reactions respectively. Under ideal conditions, water can be completely decomposed to generate hydrogen and oxygen, or act on the degradation process of organic pollutants.

[0007] Cadmium selenide, as a classic photocatalytic semiconductor material, has been widely used in hydrogen production, but its inherently sluggish hydrogen evolution reaction kinetics remain unresolved. Constructing heterojunction composite systems is an effective material modification strategy; by combining them with other functional materials, the spatial separation efficiency and interfacial migration rate of photogenerated carriers can be significantly improved, thereby enhancing photocatalytic hydrogen production performance. This technological approach provides a new research direction for the development of low-cost, high-efficiency cadmium selenide-based catalysts. Summary of the Invention

[0008] In view of this, to address the technical problem of improving the photocatalytic hydrogen production performance of cadmium selenide, the present invention provides a method for modifying cadmium selenide photocatalysts with bimetallic sulfides. High-purity and well-crystallized cadmium selenide / copper molybdenum sulfide (CdSe / Cu2MoS4) was successfully prepared using a solvothermal synthesis method. By constructing a heterojunction, cadmium selenide (CdSe) was successfully modified, greatly improving its photocatalytic hydrogen production performance. This provides a new pathway for modifying existing photocatalysts and injects new impetus into the development of photocatalytic hydrogen production technology.

[0009] To achieve the above objectives, the present invention provides the following technical solution:

[0010] In a first aspect, the present invention provides a method for modifying cadmium selenide photocatalysts with bimetallic sulfides, wherein cadmium selenide / copper molybdenum sulfide is prepared by hydrothermal reaction of copper molybdenum sulfide with cadmium selenide.

[0011] Preferably, the mass of the added molybdenum copper sulfide is 2wt% to 10wt% of the mass of the cadmium selenide.

[0012] Preferably, the mass of the added molybdenum copper sulfide is 2wt% to 4wt% of the mass of the added cadmium selenide.

[0013] Preferably, the mass of the added molybdenum copper sulfide is 3 wt% of the mass of the cadmium selenide.

[0014] Preferably, the hydrothermal reaction of copper molybdenum sulfide with cadmium selenide is as follows:

[0015] Cadmium chloride pentahydrate, sodium selenite pentahydrate and diethylenetriamine were mixed and reacted thoroughly. After adding hydrazine hydrate and mixing thoroughly, the mixture was subjected to a hydrothermal reaction. After the reaction, the mixture was washed, vacuum dried and ground to obtain cadmium selenide.

[0016] Before the hydrothermal reaction, copper molybdenum sulfide was added, and then the hydrothermal reaction was carried out. After the reaction, the mixture was washed, vacuum dried, and ground to obtain the cadmium selenide / copper molybdenum sulfide composite.

[0017] Preferably, the method for preparing copper molybdenum sulfide includes the following steps:

[0018] Cuprous oxide was dispersed in ethylene glycol, and then sodium molybdate and thioacetamide were added. After thorough mixing, a solvothermal reaction was carried out. After the reaction, the mixture was washed, vacuum dried, and then ground to obtain copper molybdenum sulfide.

[0019] Preferably, the method for preparing cuprous oxide includes the following steps:

[0020] Copper sulfate, sodium citrate, and sodium hydroxide were mixed and reacted thoroughly. Then, ascorbic acid aqueous solution was added and reacted thoroughly. After standing, washing, vacuum drying, and grinding, cuprous oxide was obtained.

[0021] Preferably, the hydrothermal reaction temperature is 100℃ and the time is 2 h.

[0022] Secondly, the present invention provides a bimetallic sulfide-modified cadmium selenide photocatalyst, which is prepared by the above-described preparation method.

[0023] Thirdly, the present invention also provides the application of bimetallic sulfide modified cadmium selenide photocatalyst in photocatalytic hydrogen production.

[0024] Compared with the prior art, the present invention has the following beneficial effects:

[0025] The method for modifying cadmium selenide photocatalysts with bimetallic sulfides provided by this invention successfully prepared high-purity and well-crystallized cadmium selenide / copper molybdenum sulfide (CdSe / Cu2MoS4) using a solvothermal synthesis method. By constructing a heterojunction, cadmium selenide (CdSe) was successfully modified, which greatly improved its photocatalytic hydrogen production performance. This provides a new path for modifying existing photocatalysts and injects new impetus into the development of photocatalytic hydrogen production technology.

[0026] This invention has technical advantages such as mild reaction conditions and strong controllability of crystal growth. Impurities can be effectively removed through self-dissolution in the solvent medium, thereby obtaining a target product with high purity, regular crystal form and uniform particle size distribution.

[0027] The successful synthesis of cadmium selenide (CdSe) with non-precious metal copper molybdenum sulfide (Cu₂MoS₄) as a cocatalyst, replacing the expensive and rare precious metal platinum (Pt), significantly reduced material costs and made large-scale applications economically feasible. The optimal performance of the CdSe / CuS₄ composite resulted in a higher hydrogen production rate than that of CdSe / Pt-supported platinum. The presence of variable-valence copper ions in the bimetallic sulfide greatly facilitated the migration of photogenerated carriers and significantly hindered their recombination. Attached Figure Description

[0028] Figure 1 This is a flowchart illustrating a method for preparing a bimetallic sulfide-modified cadmium selenide photocatalyst, as provided in a specific embodiment of the present invention.

[0029] Figure 2 The diagram shows the reaction process of a method for preparing a bimetallic sulfide-modified cadmium selenide photocatalyst according to a specific embodiment of the present invention.

[0030] Figure 3 XRD patterns of the CdSe / Cu2MoS4 photocatalysts prepared in Examples 1-6, the pure copper molybdenum sulfide prepared in S2 in Example 1, and the pure cadmium selenide prepared in Comparative Example 1.

[0031] Figure 4 Comparison of hydrogen evolution rates for CdSe / Cu2MoS4 photocatalysts prepared in Examples 1-6, pure cadmium selenide prepared in Comparative Example 1, and CdSe / 1%Pt prepared in Comparative Example 2.

[0032] Figure 5 Electrochemical test diagrams of the CdSe / Cu2MoS4 photocatalysts prepared in Examples 1-5 and the pure cadmium selenide prepared in Comparative Example 1 (A: Electrochemical impedance spectroscopy, B: Open circuit voltage decay curve, C: Transient photocurrent response, D: Linear scan voltammetry). Detailed Implementation

[0033] This invention provides a method for modifying cadmium selenide photocatalysts with bimetallic sulfides, wherein cadmium selenide / copper molybdenum sulfide is prepared by hydrothermal reaction of copper molybdenum sulfide with cadmium selenide.

[0034] In this invention, the mass of the added molybdenum copper sulfide is 1wt% to 10wt% of the mass of the cadmium selenide, preferably 2wt% to 10wt%, more preferably 2wt% to 4wt%, such as 2wt%, 3wt%, 4wt%, and most preferably 3wt%.

[0035] In this invention, the hydrothermal reaction of copper molybdenum sulfide and cadmium selenide specifically involves:

[0036] Cadmium chloride pentahydrate, sodium selenite pentahydrate and diethylenetriamine were mixed and reacted thoroughly. After adding hydrazine hydrate and mixing thoroughly, the mixture was subjected to a hydrothermal reaction. After the reaction, the mixture was washed, vacuum dried and ground to obtain cadmium selenide.

[0037] Molybdenum copper sulfide was added before the hydrothermal reaction, followed by washing, vacuum drying, and grinding to obtain the cadmium selenide / molybdenum copper sulfide composite. The reaction equation is as follows:

[0038] ;

[0039] The preferred molar ratio of cadmium chloride pentahydrate and sodium selenite pentahydrate is 1:1, with 18 mL of diethylenetriamine added and 5 mL of hydrazine hydrate. The preferred hydrothermal reaction temperature is 100℃, and the preferred reaction time is 2 h.

[0040] In this invention, the method for preparing copper molybdenum sulfide includes the following steps:

[0041] Cuprous oxide was dispersed in ethylene glycol, then sodium molybdate and thioacetamide were added. After thorough mixing, a solvothermal reaction was carried out. Following the reaction, the mixture was washed, vacuum dried, and then ground to obtain copper molybdenum sulfide. The preferred dosages are as follows:

[0042] Cuprous oxide was dispersed in ethylene glycol, then sodium molybdate and thioacetamide were added. After thorough mixing, a solvothermal reaction was carried out at 160℃ for 12 h. The molar ratio of cuprous oxide, sodium molybdate, and thioacetamide was 0.16:0.19:1. After the reaction, the mixture was washed, vacuum dried, and ground to obtain copper molybdenum sulfide (Cu2MoS4). The specific reaction is as follows:

[0043] ;

[0044] In this invention, the method for preparing cuprous oxide includes the following steps:

[0045] Copper sulfate, sodium citrate, and sodium hydroxide are mixed and reacted thoroughly. Ascorbic acid aqueous solution is then added and reacted completely. After standing, washing, vacuum drying, and grinding, cuprous oxide is obtained. The preferred dosage is as follows:

[0046] Copper sulfate, sodium citrate, and sodium hydroxide in a molar ratio of 0.06:0.017:1 were mixed and allowed to react fully. Then, ascorbic acid aqueous solution was added and allowed to react fully. After standing, washing, vacuum drying, and grinding, cuprous oxide (Cu2O) was obtained.

[0047] In this step, the reactants first react to form copper hydroxide, which is then reduced to cuprous oxide by ascorbic acid. The specific reaction is as follows:

[0048] ;

[0049] The technical solution of the present invention will be clearly and thoroughly described below with reference to specific embodiments. Example 1

[0050] The preparation of bimetallic sulfide-modified cadmium selenide photocatalysts includes the following steps:

[0051] S1. Copper sulfate, sodium citrate, and sodium hydroxide in a molar ratio of 0.06:0.017:1 were mixed and allowed to react fully. Then, ascorbic acid aqueous solution was added and allowed to react fully. After standing, washing, vacuum drying, and grinding, cuprous oxide (Cu2O) was obtained.

[0052] In this step, the reactants first react to form copper hydroxide, which is then reduced to cuprous oxide by ascorbic acid. The specific reaction is as follows:

[0053] ;

[0054] S2. Cuprous oxide was dispersed in ethylene glycol, then sodium molybdate and thioacetamide were added. After thorough mixing, a solvothermal reaction was carried out at 160℃ for 12 h. The molar ratio of cuprous oxide, sodium molybdate, and thioacetamide was 0.16:0.19:1. After the reaction, the mixture was washed, vacuum dried, and ground to obtain copper molybdenum sulfide (Cu2MoS4). The specific reaction is as follows:

[0055] ;

[0056] S3. Cadmium chloride pentahydrate, sodium selenite pentahydrate, and 18 mL of diethylenetriamine were mixed in a molar ratio of 1:1 and reacted thoroughly. Then, 5 mL of hydrazine hydrate was added and mixed thoroughly. The mixture was then subjected to a hydrothermal reaction at 100°C for 2 h. After the reaction, the mixture was washed, vacuum dried, and ground to obtain cadmium selenide (CdSe). The specific reaction is as follows:

[0057] ;

[0058] S4. Before the hydrothermal reaction in step S3, add copper molybdenum sulfide (Cu2MoS4). The mass of copper molybdenum sulfide (Cu2MoS4) added is 2wt% of the mass of cadmium selenide (CdSe) synthesized by hydrothermal reaction. Then carry out the hydrothermal reaction. After the reaction, wash, vacuum dry and grind to obtain cadmium selenide / copper molybdenum sulfide (CdSe / 2%Cu2MoS4) composite, and obtain CdSe / 2%Cu2MoS4 photocatalyst. Example 2

[0059] This embodiment is similar to Embodiment 1, except that in this embodiment, copper molybdenum sulfide is added before the hydrothermal reaction in step S3. The mass of copper molybdenum sulfide (Cu2MoS4) added is 3wt% of the mass of cadmium selenide (CdSe) synthesized by hydrothermal synthesis, thus obtaining a CdSe / 3%Cu2MoS4 photocatalyst. Example 3

[0060] This embodiment is similar to Embodiment 1, except that in this embodiment, copper molybdenum sulfide is added before the hydrothermal reaction in step S3. The mass of copper molybdenum sulfide (Cu2MoS4) added is 4 wt% of the mass of cadmium selenide (CdSe) synthesized by hydrothermal synthesis, thus obtaining a CdSe / 4%Cu2MoS4 photocatalyst. Example 4

[0061] This comparative example is similar to Example 1, except that in this comparative example, copper molybdenum sulfide is added before the hydrothermal reaction in step S3. The mass of copper molybdenum sulfide (Cu2MoS4) added is 1 wt% of the mass of cadmium selenide (CdSe) synthesized by hydrothermal synthesis, thus obtaining a CdSe / 1%Cu2MoS4 photocatalyst. Example 5

[0062] This comparative example is similar to Example 1, except that in this comparative example, copper molybdenum sulfide is added before the hydrothermal reaction in step S3. The mass of copper molybdenum sulfide (Cu2MoS4) added is 5 wt% of the mass of cadmium selenide (CdSe) synthesized by hydrothermal synthesis, thus obtaining a CdSe / 5%Cu2MoS4 photocatalyst. Example 6

[0063] This comparative example is similar to Example 1, except that in this comparative example, copper molybdenum sulfide is added before the hydrothermal reaction in step S3. The mass of copper molybdenum sulfide (Cu2MoS4) added is 10 wt% of the mass of cadmium selenide (CdSe) synthesized by hydrothermal synthesis, thus obtaining a CdSe / 10%Cu2MoS4 photocatalyst.

[0064] Comparative Example 1

[0065] In this comparative example, no copper molybdenum sulfide was added before the hydrothermal reaction in step S3, and pure CdSe photocatalyst was obtained.

[0066] Comparative Example 2

[0067] CdSe loaded with 1% Pt was synthesized via a thermal in-situ deposition method. The specific steps are as follows: First, 200 mg of pure cadmium selenide prepared in Comparative Example 1 was weighed and uniformly dispersed in 5.4 mL of 1.91 mM chloroplatinic acid (H₂PtCl₆·H₂O) solution. Then, the sample was heated in a water bath at 80 °C until the water evaporated and the sample became sol-like. The sample was then dried in an oven at 80 °C. Next, the resulting sample was dispersed in ethylene glycol and heated in a water bath at 100 °C for 30 min. After the reaction was complete, the sample was collected by centrifugation and washed multiple times with deionized water and ethanol. Finally, the sample was vacuum dried at 80 °C to obtain the CdSe / 1%Pt photocatalyst.

[0068] Figure 1 This is a flowchart illustrating a method for preparing a bimetallic sulfide-modified cadmium selenide photocatalyst, as provided in a specific embodiment of the present invention. From... Figure 1 As can be seen, the present invention first prepares Cu2O nanocubes using CuSO4, NaOH and ascorbic acid as raw materials, then mixes the obtained Cu2O with thioacetamide and Na2MoO4 for a solvothermal reaction to obtain Cu2MoS4 nanosheets; then mixes CdCl2, Na2SeO3 and hydrazine hydrate for a reaction, and then adds Cu2MoS4 for a hydrothermal reaction to obtain a CdSe / Cu2MoS4 composite.

[0069] Figure 2 The diagram shows the reaction process of a method for preparing a bimetallic sulfide-modified cadmium selenide photocatalyst according to a specific embodiment of the present invention.

[0070] Figure 3XRD patterns of the CdSe / Cu2MoS4 photocatalysts prepared in Examples 1-6, the pure copper molybdenum sulfide prepared in S2 of Example 1, and the pure cadmium selenide prepared in Comparative Example 1. Figure 3 As can be seen, all diffraction peaks correspond to the standard data card, and there are no additional diffraction peaks, indicating that pure cadmium selenide, pure copper molybdenum sulfide, and a series of CdSe / Cu2MoS4 photocatalysts were prepared.

[0071] Figure 4 Comparison of hydrogen evolution rates for the CdSe / Cu2MoS4 photocatalysts prepared in Examples 1-6, the pure cadmium selenide prepared in Comparative Example 1, and the CdSe / 1%Pt photocatalyst prepared in Comparative Example 2. Analysis Figure 4 The hydrogen production rate of pure cadmium selenide (Comparative Example 1) was found to be 532.34 μmol·g. -1 ·h -1 The hydrogen production rate of 1% Pt / CdSe (Comparative Example 2) was 1421.5 μmol·g. -1 ·h -1 The hydrogen production rate of the cadmium selenide / copper molybdenum sulfide (CdSe / 2%Cu2MoS4) composite prepared in Example 1 was 3345.1 μmol·g. -1 ·h -1 The hydrogen production rate was 6.29 times that of pure cadmium selenide; the hydrogen production rate of the cadmium selenide / copper molybdenum sulfide (CdSe / 3%Cu2MoS4) composite prepared in Example 2 was 5543.9 μmol·g. -1 ·h -1 The hydrogen production rate was 10.4 times that of pure cadmium selenide. The cadmium selenide / copper molybdenum sulfide composite at this ratio exhibited the best hydrogen production performance, with a hydrogen production rate 3.9 times that of 1% Pt / CdSe. The cadmium manganese sulfide / copper molybdenum sulfide (CdSe / 4% Cu2MoS4) composite prepared in Example 3 had a hydrogen production rate of 4625.2 μmol·g. -1 ·h -1 The hydrogen production rate was 8.7 times that of cadmium selenide; the hydrogen production rate of the cadmium selenide / copper molybdenum sulfide (CdSe / 1%Cu2MoS4) composite prepared in Example 4 was 1000.8 μmol·g. -1 ·h -1 The hydrogen production rate was 1.88 times that of cadmium selenide; the hydrogen production rate of the cadmium selenide / copper molybdenum sulfide (CdSe / 5%Cu2MoS4) composite prepared in Example 5 was 1976.8 μmol·g. -1 ·h -1 The hydrogen production rate was 3.7 times that of cadmium selenide; the hydrogen production rate of the cadmium selenide / copper molybdenum sulfide (CdSe / 10%Cu2MoS4) composite prepared in Example 6 was 1720.4 μmol·g. -1 ·h-1 Its performance is far lower than that of other CdSe / Cu2MoS4 photocatalyst ratios.

[0072] Figure 5 Electrochemical test graphs for the CdSe / Cu2MoS4 photocatalysts prepared in Examples 1-5 and the pure cadmium selenide prepared in Comparative Example 1 are shown, where A: electrochemical impedance spectroscopy, B: open-circuit voltage decay curve, C: transient photocurrent response curve, and D: linear sweep voltammetry curve. Figure 5 As can be seen from A, compared to other samples, CdSe / 3%Cu2MoS4 has the smallest curve radius, indicating that it has the smallest electrochemical impedance value and also indicates that it has the strongest ability to promote carrier migration and separation; Figure 5 In component B, the open potential of CdSe / 3%Cu2MoS4 decays the slowest, indicating a significantly improved charge separation effect; from Figure 5 As can be seen from C, the photocurrent intensity of CdSe / 3%Cu2MoS4 is significantly stronger than that of other samples, indicating that it has the highest carrier separation efficiency; Figure 5 In D, compared to pure CdSe, CdSe / 3%Cu2MoS4 exhibits a smaller overpotential, which means it has a stronger reducing ability and is more conducive to the photocatalytic hydrogen evolution reaction.

[0073] The above description is merely a preferred embodiment of the present invention. However, the scope of protection of the present invention is not limited thereto; any equivalent substitutions or modifications made by those skilled in the art within the technical scope disclosed in the present invention, based on the technical solution and its improved concept, should be covered within the scope of protection of the present invention.

Claims

1. A method for modifying cadmium selenide photocatalysts with bimetallic sulfides, characterized in that, Cadmium selenide / molybdenum sulfide copper was prepared by hydrothermal reaction of molybdenum sulfide copper with cadmium selenide. The hydrothermal reaction between copper molybdenum sulfide and cadmium selenide is as follows: Cadmium chloride pentahydrate, sodium selenite pentahydrate and diethylenetriamine were mixed and reacted thoroughly. After adding hydrazine hydrate and mixing thoroughly, the mixture was subjected to a hydrothermal reaction. After the reaction, the mixture was washed, vacuum dried and ground to obtain cadmium selenide. Before the hydrothermal reaction, copper molybdenum sulfide was added, and then the hydrothermal reaction was carried out. After the reaction, the mixture was washed, vacuum dried, and ground to obtain the cadmium selenide / copper molybdenum sulfide composite. The mass of the added molybdenum copper sulfide is 2wt% to 4wt% of the mass of the added cadmium selenide.

2. The method for modifying cadmium selenide photocatalyst with bimetallic sulfides according to claim 1, characterized in that, The mass of the added molybdenum copper sulfide is 3 wt% of the mass of the added cadmium selenide.

3. The method for modifying cadmium selenide photocatalyst with bimetallic sulfides according to claim 1, characterized in that, The preparation method of copper molybdenum sulfide includes the following steps: Cuprous oxide was dispersed in ethylene glycol, and then sodium molybdate and thioacetamide were added. After thorough mixing, a solvothermal reaction was carried out. After the reaction, the mixture was washed, vacuum dried, and then ground to obtain copper molybdenum sulfide.

4. The method for modifying cadmium selenide photocatalyst with bimetallic sulfides according to claim 3, characterized in that, The preparation method of cuprous oxide includes the following steps: Copper sulfate, sodium citrate, and sodium hydroxide were mixed and reacted thoroughly. Then, ascorbic acid aqueous solution was added and reacted thoroughly. After standing, washing, vacuum drying, and grinding, cuprous oxide was obtained.

5. A method for modifying cadmium selenide photocatalysts with bimetallic sulfides according to any one of claims 1-4, characterized in that, The hydrothermal reaction temperature was 100℃ and the reaction time was 2 hours.

6. A bimetallic sulfide-modified cadmium selenide photocatalyst, characterized in that, It is prepared by the preparation method according to any one of claims 1-5.

7. The application of the bimetallic sulfide-modified cadmium selenide photocatalyst according to claim 6 in photocatalytic hydrogen production.

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