High-entropy selenide photocatalyst and preparation method thereof

Abstract

The embodiment of the invention provides a preparation method of a high-entropy selenide photocatalyst, which comprises the following steps: adding a certain amount of metal salt into an organic solvent, ultrasonically dispersing uniformly, stirring the mixed solution in a stirrer, slowly adding a reducing agent in the stirring process, and stirring for a certain time to obtain a metal mixed solution; adding a selenium source into the prepared metal mixed solution, and continuously stirring until the selenium source is dissolved to obtain a reaction solution; and transferring the reaction solution into a microwave reaction kettle, heating to a certain temperature, keeping for a certain time, and washing and drying the obtained precipitate after the reaction is finished, thereby obtaining the high-entropy selenide photocatalyst. The high-entropy selenide photocatalyst prepared by the preparation method disclosed by the invention has the advantage of high photocatalytic hydrogen production efficiency. Meanwhile, the preparation method is simple in technological process and suitable for being applied to large-scale industrial production.

Description

Technical Field

[0001] The present invention belongs to the field of environmental protection and energy materials, and more specifically, relates to a high-entropy selenide photocatalyst and a preparation method thereof. Background Art

[0002] As people pay more and more attention to renewable energy, solar energy, as one of the most abundant and sustainable energy sources, has attracted much attention. By directly converting solar energy into hydrogen, we can not only make full use of the huge energy reserves in nature, but also avoid dependence on limited fossil fuels, thereby slowing down the over-exploitation of earth's resources. Compared with traditional hydrogen production methods, the photocatalytic hydrogen production process does not produce harmful gases such as carbon dioxide, which helps to alleviate greenhouse gas emissions and mitigate the adverse effects of climate change.

[0003] Semiconductor photocatalysis is the process of generating photogenerated electron-hole pairs when a semiconductor photocatalyst is excited by photon energy greater than its bandgap width. The electrons in the valence band are excited to transition from the ground state to the excited state and to the conduction band, and the photogenerated electron-hole pairs are separated. The separated photogenerated electrons and holes migrate to the catalyst surface and react respectively. Holes have the ability to oxidize organic pollutants, and electrons have the ability to reduce, which can achieve photocatalytic hydrogen and oxygen production, carbon dioxide reduction, and nitrogen fixation. However, this photocatalytic technology has low efficiency in photon absorption and carrier separation, and has a high recombination rate of photogenerated electrons and holes. These defects result in insufficient efficiency in photocatalytic hydrogen production, which hinders its further development and application. Summary of the invention

[0004] In view of the above, the present invention aims to solve at least one of the technical problems existing in the prior art. To this end, the present invention proposes a high entropy selenide photocatalyst and a preparation method thereof, which are used to prepare a high entropy selenide photocatalyst with high efficiency of photocatalytic hydrogen production. The high entropy selenide photocatalyst prepared by the preparation method of the present invention has the advantages of high efficiency of photocatalytic hydrogen production. At the same time, the preparation method has a simple process flow and is suitable for application in large-scale industrial production.

[0005] To this end, in the first aspect, an embodiment of the present invention provides a method for preparing a high-entropy selenide photocatalyst, the preparation method comprising: adding a certain amount of metal salt to an organic solvent, ultrasonically dispersing the mixed solution uniformly and placing the mixed solution in a stirrer for stirring, slowly adding a reducing agent during the stirring process, and stirring for a certain time to obtain a metal mixed solution; adding a selenium source to the prepared metal mixed solution, and continuously stirring until the selenium source is dissolved to obtain a reaction solution; transferring the reaction solution to a microwave reactor, heating it to a certain temperature and maintaining it for a certain time, and after the reaction is completed, washing and drying the obtained precipitate to obtain the high-entropy selenide photocatalyst.

[0006] Preferably, the metal salt is one or more of nitrates, chlorides and sulfates, the metal elements are five or more of cadmium, zinc, manganese, copper, cerium, yttrium, lanthanum, zirconium, chromium and magnesium, and the molar ratio of each metal salt to the organic solvent is 1:(0.1-10).

[0007] Preferably, the organic solvent is one or more of ethylenediamine, diethylenetriamine, triethylenetetramine, tetraethylenepentamine, aniline, ethylamine, propylamine, isopropylamine, dimethylformamide and hexamethylenetetramine, the reducing agent is hydrazine hydrate, and the volume ratio of the organic solvent to the reducing agent is 1:(0.1-10).

[0008] Preferably, the instrument used for the ultrasonic dispersion is an ultrasonic machine or an ultrasonic cell disruptor, the ultrasonic time is 0.5-6 hours, and the stirring time is 2-10 hours.

[0009] Preferably, the selenium source is one or more of sodium selenite, selenium powder, selenol, selenoprotein, selenium-containing amino acid, selenoether and selenolphenol, and the molar ratio of each metal salt to the selenium source is 1:(0.2-10).

[0010] Preferably, the stirring time is 2-10 hours.

[0011] Preferably, the heating temperature is 120-160° C., the heating rate is 5-10° C. / min, and the insulation time is 10-60 min.

[0012] Preferably, the washing method is one or a combination of centrifugal washing and suction filtration washing, and the detergent is anhydrous ethanol or water.

[0013] Preferably, the drying method is one or more of forced air drying, vacuum drying, freeze drying, and spray drying, and the drying time is 24 hours.

[0014] In a second aspect, an embodiment of the present invention provides a high entropy selenide photocatalyst, wherein the high entropy selenide photocatalyst is prepared by the preparation method of the high entropy selenide photocatalyst provided in the first aspect above.

[0015] The preparation method of the high entropy selenide photocatalyst provided by the embodiment of the present invention introduces a variety of different metal elements into the lattice of the selenide during the preparation process, resulting in the formation of more active sites, thereby improving the catalytic activity of the photocatalytic hydrogen production reaction, helping to promote the catalytic step in the water decomposition reaction and increasing the reaction rate; in addition, the preparation method of the present invention introduces a multi-element composition during the preparation process to change the electronic band structure of the selenide, causing the adjustment of the crystal electronic structure, which can reduce the transmission resistance of electrons in the selenide lattice, help improve the mobility of electrons, make it easier to pass through the material, thereby promoting the rapid transmission of electrons and preventing the recombination of electrons and holes. At the same time, the preparation method has a simple process flow and is suitable for application in large-scale industrial production. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 A flow chart of a method for preparing a high entropy selenide photocatalyst provided in an embodiment of the present invention;

[0017] Figure 2 This is a field emission scanning electron microscope image of the high entropy selenide photocatalyst prepared in Example 1 of the present invention;

[0018] Figure 3 This is the XRD pattern of the high entropy selenide photocatalyst prepared in Example 1 of the present invention;

[0019] Figure 4 This is a field emission scanning electron microscope elemental mapping image of the high entropy selenide photocatalyst prepared in Example 1 of the present invention. DETAILED DESCRIPTION

[0020] Embodiments of the present invention are described in detail below, examples of which are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements having the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are intended to be used to explain the present invention, and should not be construed as limiting the present invention.

[0021] The disclosure below provides many different embodiments or examples to implement different structures of the present invention. In order to simplify the disclosure of the present invention, the parts and settings of specific examples are described below. Of course, they are only examples, and the purpose is not to limit the present invention. In addition, the present invention can repeat reference numbers and / or letters in different examples. This repetition is for the purpose of simplicity and clarity, and does not itself indicate the relationship between the various embodiments and / or settings discussed. In addition, the present invention provides various specific processes and examples of materials, but those of ordinary skill in the art can be aware of the applicability of other processes and / or the use of other materials.

[0022] The purpose of the present invention is to provide a high-entropy selenide photocatalyst and a preparation method thereof. The high-entropy selenide photocatalyst prepared by the present invention can effectively enhance the absorption of light and red-shift the absorption band edge of the catalyst from the ultraviolet band to the visible light band, thereby effectively improving the utilization of visible light with lower photon energy and having high efficiency of photocatalytic hydrogen production.

[0023] The present invention provides a method for preparing a high entropy selenide photocatalyst. Figure 1 As shown, the preparation method comprises the following steps:

[0024] Step S1: adding a certain amount of metal salt to an organic solvent, and placing the mixed solution in a stirrer to stir after ultrasonic dispersion. During the stirring process, slowly adding a reducing agent, and stirring for a certain period of time to obtain a metal mixed solution;

[0025] Wherein, the metal salt may be one or more of nitrate, chloride and sulfate, and the metal element may be five or more of cadmium, zinc, manganese, copper, cerium, yttrium, lanthanum, zirconium, chromium and magnesium; in an embodiment of the present invention, the molar ratio of each metal salt to the organic solvent is 1:(0.1-10). The organic solvent may be one or more of ethylenediamine, diethylenetriamine, triethylenetetramine, tetraethylenepentamine, aniline, ethylamine, propylamine, isopropylamine, dimethylformamide and hexamethylenetetramine, and the reducing agent may be hydrazine hydrate; in an embodiment of the present invention, the volume ratio of the amount of the organic solvent to the amount of the reducing agent is 1:(0.1-10). The instrument used for ultrasonic dispersion is an ultrasonic machine or an ultrasonic cell disruptor, and the ultrasonic time may be 0.5-6 hours. The stirring time may be 2-10h.

[0026] Step S2: adding a selenium source to the metal mixed solution prepared above, and continuously stirring until the selenium source is dissolved to obtain a reaction solution;

[0027] The selenium source may be one or more of sodium selenite, selenium powder, selenol, selenoprotein, selenium-containing amino acid, selenoether and selenolphenol. In the embodiment of the present invention, the molar ratio of each metal salt to the selenium source is 1:(0.2-10). The stirring time may be 2-10 hours.

[0028] Step S3: transferring the reaction solution to a microwave reactor, heating it to a certain temperature and keeping it warm for a certain time, washing and drying the obtained precipitate after the reaction is completed, thereby obtaining a high entropy selenide photocatalyst;

[0029] The heating temperature is 120-160°C, the heating rate is 5-10°C / min, and the heat preservation time is 10-60min. The washing method can be one or a combination of centrifugal washing and suction filtration washing, and the detergent can be anhydrous ethanol or water; the drying method can be one or more of blast drying, vacuum drying, freeze drying, and spray drying, and the drying time can be 24h.

[0030] The preparation method of the high entropy selenide photocatalyst provided by the embodiment of the present invention introduces a variety of different metal elements into the lattice of the selenide during the preparation process, resulting in the formation of more active sites, thereby improving the catalytic activity of the photocatalytic hydrogen production reaction, helping to promote the catalytic step in the water decomposition reaction and increasing the reaction rate; in addition, the preparation method of the present invention introduces a multi-element composition during the preparation process to change the electronic band structure of the selenide, causing the adjustment of the crystal electronic structure, which can reduce the transmission resistance of electrons in the selenide lattice, help improve the mobility of electrons, make it easier to pass through the material, thereby promoting the rapid transmission of electrons and preventing the recombination of electrons and holes. At the same time, the preparation method has a simple process flow and is suitable for application in large-scale industrial production.

[0031] The high entropy selenide photocatalyst prepared by the preparation method of the present invention can effectively enhance the absorption of light and red-shift the absorption band edge of the catalyst from the ultraviolet band to the visible light band, thereby effectively improving the utilization of visible light with lower photon energy.

[0032] The specific process and effect of the preparation method of the high entropy selenide photocatalyst of the present invention are further described in detail below in conjunction with some specific embodiments, but are not limited to the protection scope of the present invention.

[0033] Example 1

[0034] This embodiment provides a method for preparing a high entropy selenide photocatalyst, comprising the following steps:

[0035] Step S1: adding 1 mmol of cadmium nitrate, zinc nitrate, copper nitrate, manganese nitrate and cerium nitrate to 20 mL of diethylenetriamine, dispersing them uniformly by ultrasonication for 1 h, and then placing the solution on a stirrer and stirring it. During the stirring process, slowly adding 8 mL of hydrazine hydrate, and then stirring the mixed solution for 2 h to obtain a metal mixed solution;

[0036] Step S2: adding 5 mmol of sodium selenite to the metal mixed solution prepared above, and stirring continuously for 4 hours to obtain a reaction solution;

[0037] Step S3: The reaction solution is transferred to a microwave reactor and heated to 140° C. and maintained for 20 min. After the reaction is completed, the obtained precipitate is washed and dried to obtain a high entropy selenide photocatalyst.

[0038] in, Figure 2 This is a field emission scanning electron microscope image of the high entropy selenide photocatalyst prepared in Example 1. Figure 2 It can be clearly seen that the high entropy selenide photocatalyst prepared in Example 1 grows uniformly and has a ribbon-like structure;

[0039] Figure 3 The XRD pattern of the high entropy selenide photocatalyst prepared in Example 1 is shown in FIG. Figure 3 It can be seen that the characteristic peak distance corresponds to pure cadmium selenide, but the peak is relatively broad. This is because the introduction of different metal elements causes the peak to be broadened and the crystallinity to be reduced.

[0040] Figure 4 This is a field emission scanning electron microscope elemental mapping image of the high entropy selenide photocatalyst prepared in Example 1.

[0041] Example 2

[0042] This embodiment provides a method for preparing a high entropy selenide photocatalyst, comprising the following steps:

[0043] Step S1: adding 1 mmol of cadmium chloride, zinc chloride, copper chloride, manganese chloride and cerium chloride to 20 mL of diethylenetriamine, dispersing them uniformly by ultrasonication for 1 h, and then placing the solution on a stirrer and stirring it. During the stirring process, slowly adding 8 mL of hydrazine hydrate, and then stirring the mixed solution for 2 h to obtain a metal mixed solution;

[0044] Step S2: adding 5 mmol of sodium selenite to the metal mixed solution prepared above, and stirring continuously for 4 hours to obtain a reaction solution;

[0045] Step S3: The reaction solution is transferred to a microwave reactor and heated to 140° C. and maintained for 20 min. After the reaction is completed, the obtained precipitate is washed and dried to obtain a high entropy selenide photocatalyst.

[0046] Example 3

[0047] This embodiment provides a method for preparing a high entropy selenide photocatalyst, comprising the following steps:

[0048] Step S1: adding 1 mmol of cadmium chloride, zinc chloride, copper chloride, manganese chloride and cerium chloride to 20 mL of diethylenetriamine, dispersing them uniformly by ultrasonication for 2 h, and then placing the solution on a stirrer and stirring it. During the stirring process, slowly adding 12 mL of hydrazine hydrate, and then stirring the mixed solution for another 2 h to obtain a metal mixed solution;

[0049] Step S2: adding 5 mmol of sodium selenite to the metal mixed solution prepared above, and stirring for 5 hours to obtain a reaction solution;

[0050] Step S3: The reaction solution is transferred to a microwave reactor and heated to 140° C. and maintained for 20 min. After the reaction is completed, the obtained precipitate is washed and dried to obtain a high entropy selenide photocatalyst.

[0051] Example 4

[0052] This embodiment provides a method for preparing a high entropy selenide photocatalyst, comprising the following steps:

[0053] Step S1: adding 1 mmol of cadmium nitrate, zinc nitrate, copper nitrate, manganese nitrate and cerium nitrate to 20 mL of diethylenetriamine, dispersing them uniformly by ultrasonication for 1 h, and then placing the solution on a stirrer and stirring it. During the stirring process, slowly adding 8 mL of hydrazine hydrate, and then stirring the mixed solution for 2 h to obtain a metal mixed solution;

[0054] Step S2: adding 5 mmol of sodium selenite to the metal mixed solution prepared above, and stirring continuously for 4 hours to obtain a reaction solution;

[0055] Step S3: The reaction solution is transferred to a microwave reactor and heated to 160° C. and maintained for 40 min. After the reaction is completed, the obtained precipitate is washed and dried to obtain a high entropy selenide photocatalyst.

[0056] In order to verify the finished product quality of the high entropy selenide photocatalyst prepared by the preparation method of the high entropy selenide photocatalyst provided in the embodiment of the present invention, the high entropy selenide photocatalyst prepared in the above Examples 1-4 was tested by the PerfectLight multi-channel photocatalytic reaction system (PCX50C Discov).

[0057] Specifically, the test steps include: weighing 25 mL of sacrificial agent (0.35 mol·L -1 Sodium sulfide and 0.25 mol·L -1 Anhydrous sodium sulfite mixed solution) was placed in a disposable plastic cup, and then 10 mg of the sample was weighed and placed in the cup. After being evenly shaken with an ultrasonic machine, it was poured into a quartz bottle, and then 60 μL of chloroplatinic acid (chloroplatinic acid concentration is 1g per 100 mL) was added. The bottle cap was tightened, and the sealed system was ventilated with nitrogen. After irradiation with an LED light source for 1 hour, 1 mL of gas was extracted from the quartz bottle with a syringe, and the gas composition was detected with a gas chromatograph (GC-7900). The test results are shown in Table 1.

[0058] Table 1. Test items and test results of Examples 1-4

[0059] Example No. <![CDATA[Hydrogen production performance (mmol·g -1 ·h -1 )]]> Example 1 16.05 Example 2 6.35 Example 3 14.45 Example 4 9.98

[0060] In summary, the preparation method of the high entropy selenide photocatalyst provided by the embodiment of the present invention introduces a variety of different metal elements into the lattice of the selenide during the preparation process, resulting in the formation of more active sites, thereby improving the catalytic activity of the photocatalytic hydrogen production reaction, helping to promote the catalytic step in the water decomposition reaction and increase the reaction rate; in addition, the preparation method of the present invention introduces a multi-element composition during the preparation process to change the electronic band structure of the selenide, causing the adjustment of the crystal electronic structure, which can reduce the transmission resistance of electrons in the selenide lattice, help improve the mobility of electrons, make it easier to pass through the material, thereby promoting the rapid transmission of electrons and preventing the recombination of electrons and holes. At the same time, the preparation method has a simple process flow and is suitable for application in large-scale industrial production.

[0061] The high entropy selenide photocatalyst prepared by the preparation method of the present invention can effectively enhance the absorption of light and red-shift the absorption band edge of the catalyst from the ultraviolet band to the visible light band, thereby effectively improving the utilization of visible light with lower photon energy.

[0062] In the description of this specification, the description with reference to the terms "one embodiment", "some embodiments", "example", "specific example", or "some examples" etc. means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described may be combined in any one or more embodiments or examples in a suitable manner. In addition, those skilled in the art may combine and combine the different embodiments or examples described in this specification and the features of the different embodiments or examples, without contradiction.

[0063] Although the embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the claims and their equivalents.

Claims

1. A method for preparing a high entropy selenide photocatalyst, characterized in that: The preparation method comprises: Step S1: adding a certain amount of metal salt to an organic solvent, and placing the mixed solution in a stirrer to stir after ultrasonic dispersion. During the stirring process, slowly adding a reducing agent, and stirring for a certain period of time to obtain a metal mixed solution; Step S2: adding a selenium source to the metal mixed solution prepared above, and continuously stirring until the selenium source is dissolved to obtain a reaction solution; Step S3: transferring the reaction solution to a microwave reactor, heating it to a certain temperature and maintaining it for a certain time, and washing and drying the obtained precipitate after the reaction is completed, thereby obtaining the high entropy selenide photocatalyst.

2. The method for preparing a high entropy selenide photocatalyst according to claim 1, characterized in that: In step S1, the metal salt is one or more of nitrates, chlorides and sulfates, the metal elements are five or more of cadmium, zinc, manganese, copper, cerium, yttrium, lanthanum, zirconium, chromium and magnesium, and the molar ratio of each metal salt to the organic solvent is 1:(0.1-10).

3. The method for preparing a high entropy selenide photocatalyst according to claim 1, characterized in that: In the step S1, the organic solvent is one or more of ethylenediamine, diethylenetriamine, triethylenetetramine, tetraethylenepentamine, aniline, ethylamine, propylamine, isopropylamine, dimethylformamide and hexamethylenetetramine, the reducing agent is hydrazine hydrate, and the volume ratio of the organic solvent to the reducing agent is 1:(0.1-10).

4. The method for preparing a high entropy selenide photocatalyst according to claim 1, characterized in that: In the step S1, the instrument used for the ultrasonic dispersion is an ultrasonic machine or an ultrasonic cell disruptor, the ultrasonic time is 0.5-6 hours, and the stirring time is 2-10 hours.

5. The method for preparing a high entropy selenide photocatalyst according to claim 1, characterized in that: In step S2, the selenium source is one or more of sodium selenite, selenium powder, selenol, selenoprotein, selenium-containing amino acid, selenoether and selenolphenol, and the molar ratio of each metal salt to the selenium source is 1:(0.2-10).

6. The method for preparing a high entropy selenide photocatalyst according to claim 1, characterized in that: In step S2, the stirring time is 2-10 hours.

7. The method for preparing a high entropy selenide photocatalyst according to claim 1, characterized in that: In step S3, the heating temperature is 120-160°C, the heating rate is 5-10°C / min, and the insulation time is 10-60min.

8. The method for preparing a high entropy selenide photocatalyst according to claim 1, characterized in that: In step S3, the washing method is one or a combination of centrifugal washing and suction filtration washing, and the washing agent is anhydrous ethanol or water.

9. The method for preparing a high entropy selenide photocatalyst according to claim 1, characterized in that: In step S3, the drying method is one or more of forced air drying, vacuum drying, freeze drying, and spray drying, and the drying time is 24 hours.

10. A high entropy selenide photocatalyst, characterized in that: The high entropy selenide photocatalyst is prepared by the preparation method according to any one of claims 1 to 9.

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