Preparation method and application of selenium-rich vacancy Cu7S4 / ZnSe-Vse composite catalyst

Abstract

The application belongs to the technical field of piezoelectric photocatalysis, and particularly relates to a preparation method and application of a Cu7S4 / ZnSe-Vse composite catalyst rich in selenium vacancies. The application first synthesizes zinc selenide material by using a hydrothermal method, prepares zinc selenide nanoparticles (ZnSe-Vse) with selenium vacancies by NaOH etching, then uses snowflake-like copper tetrasulfide (Cu7S4) as a cocatalyst, and finally adopts an ultrasonic stirring method to make the two composite to form a heterojunction, thereby preparing the Cu7S4 / ZnSe-Vse composite catalyst rich in selenium vacancies. The catalyst can efficiently catalyze H2 production under the synergistic action of sunlight irradiation and ultrasonic vibration, has abundant active sites, excellent stability and hydrogen production effect, and has the advantages of short preparation period, low cost and simple process.

Description

Technical Field

[0001] This invention belongs to the field of piezoelectric photocatalysis technology, specifically relating to a method for preparing and applying a selenium-vacancy-rich Cu7S4 / ZnSe-Vse composite catalyst. Background Technology

[0002] For a long time, fossil fuels have played a vital role in meeting human energy consumption needs and maintaining social prosperity and development due to their economic availability. Currently, approximately 90% of the world's energy comes from fossil fuels. However, fossil fuels are non-renewable, and their combustion produces harmful gases and large amounts of CO2, causing severe environmental problems such as acid rain, the greenhouse effect, and climate change globally. Therefore, developing clean and renewable energy is an inevitable choice for sustainable development. Hydrogen, as a new type of green energy, has advantages such as high calorific value and environmental friendliness, and is highly favored by scientists.

[0003] In recent years, the conversion of abundant solar energy into hydrogen energy using semiconductor photocatalysts has become a promising new technology in the development of green and ideal energy sources. However, the performance of photocatalytic hydrogen production remains severely limited by electron-hole recombination. Notably, non-centrosymmetric piezoelectric materials can generate a piezoelectric field through mechanical force, thereby promoting the separation of photogenerated charges. Therefore, the combination of piezoelectric catalysis and photocatalysis holds promise for significantly improving hydrogen production. Zinc selenide (ZnSe) semiconductor materials possess diverse morphologies, suitable band structures (2.67 eV), and excellent stability, and have been used in fields such as photocatalytic water splitting for hydrogen production and photocatalytic degradation of organic dyes. Compared to the widely reported cadmium selenide (CdSe) semiconductor, it does not contain the toxic element Cd, is inexpensive, and environmentally friendly, thus being considered an ideal semiconductor for photocatalytic hydrogen production. To overcome the high recombination rate of electron-hole pairs on single-component ZnSe photocatalysts, loading a co-catalyst and forming Se vacancies are effective modification methods. For example, patent CN117599813A discloses a method for preparing a zinc selenide-containing heterojunction photocatalyst for water splitting to produce hydrogen. Although the prepared catalyst improves the photocatalytic efficiency and the mobility of photogenerated carriers, the above-mentioned catalyst synthesis method is cumbersome, costly, has poor stability, and is not easy to operate. Summary of the Invention

[0004] The purpose of this invention is to provide a method for preparing a Cu7S4 / ZnSe-Vse composite catalyst rich in selenium vacancies, and to apply it to piezoelectric photocatalytic H2 production. The prepared catalyst has higher catalytic performance, stronger corrosion resistance, and is easier to operate.

[0005] The method for preparing the selenium-vacancy-rich Cu7S4 / ZnSe-Vse composite catalyst provided by this invention includes the following steps:

[0006] (1) Preparation of ZnSe-Vse:

[0007] Dissolve selenium powder in distilled water and stir for 30 minutes until fully dissolved. Then slowly add sodium borohydride and continue stirring until clear. Finally, add Zn(NO3)2. 3)2 ·6H2O, stir for 10 min, then transfer to a reaction vessel with a polytetrafluoroethylene liner, place in an oven at 180℃ for 8 h. After the reaction is complete, cool to room temperature, wash the solid in the reaction vessel three times with deionized water and anhydrous ethanol, and vacuum dry at 60℃ for 12 h to obtain ZnSe powder without selenium vacancies. Then disperse it in NaOH solution and sonicate for half an hour. After the reaction is complete, vacuum dry the separated solid to obtain ZnSe-Vse.

[0008] Furthermore, the selenium powder and Zn(NO) 3)2 The mass ratio of ·6H2O is 0.8:3.0.

[0009] Furthermore, the mass ratio of sodium borohydride to Se is 1:1.

[0010] Furthermore, the concentration of the NaOH solution is 0.3 mol / L.

[0011] (2) Preparation of Cu7S4

[0012] Cu(NO3)2·6H2O was dissolved in ethylenediamine and stirred for 20 min to ensure complete dispersion. Thiourea was then added and stirred for 30 min. The mixture was then transferred to a reaction vessel with a polytetrafluoroethylene liner and placed in an oven at 120 °C for 2 h. After the reaction was completed, the mixture was cooled to room temperature. The solid in the reaction vessel was washed three times with deionized water and anhydrous ethanol and dried overnight at 60 °C to obtain black Cu7S4 powder.

[0013] Furthermore, the molar ratio of Cu(NO3)2·6H2O to thiourea is 1:1.

[0014] (3) Preparation of Cu7S4 / ZnSe-Vse composite catalyst rich in selenium vacancies:

[0015] ZnSe-Vse and Cu7S4 were dissolved in a solvent, subjected to ultrasonication and stirring, filtered, washed and dried at room temperature, and finally a dark green powder was obtained, which is the Cu7S4 / ZnSe-Vse composite catalyst rich in selenium vacancies.

[0016] Furthermore, the mass of Cu7S4 is 5–11% of the mass of ZnSe-Vse.

[0017] Preferably, the mass of Cu7S4 added is 7 to 9% of the mass of ZnSe-Vse.

[0018] Furthermore, the solvent includes at least one of deionized water and anhydrous ethanol;

[0019] Furthermore, when the solvent is a mixed solution of anhydrous ethanol and water, the volume ratio of anhydrous ethanol to water is 1-4:1.

[0020] Furthermore, the ultrasonic power is 240W, and the time is 1 hour; the stirring speed is 400 r / min, and the time is 4 hours.

[0021] The selenium-vacancy-rich Cu7S4 / ZnSe-Vse composite catalyst prepared by the above method is used for piezoelectric photocatalytic H2 production. The specific application method includes the following steps: uniformly disperse the selenium-vacancy-rich Cu7S4 / ZnSe-Vse composite catalyst in water, uniformly disperse it by ultrasound, then add a sacrificial agent, pass N2 through, and carry out the reaction in a sealed environment under ultrasonic vibration and simulated sunlight to catalyze H2 production.

[0022] Furthermore, the ultrasonic power is 240W; the simulated sunlight is generated by a xenon lamp with a power of 55W.

[0023] Furthermore, the amount of the selenium-vacancy-rich Cu7S4 / ZnSe-Vse composite catalyst used in deionized water was 2 mg / 18 mL.

[0024] Furthermore, the sacrificial agent is one of triethanolamine, lactic acid, a mixed solution of 0.35M Na2S and 0.25M Na2SO3.

[0025] Preferably, the sacrificial agent is a mixed solution of 0.35M Na2S and 0.25M Na2SO3.

[0026] Compared with the prior art, the present invention has achieved the following beneficial effects:

[0027] (1) The Cu7S4 / ZnSe-Vse composite catalyst rich in selenium vacancies provided by the present invention is formed by combining nanoparticle ZnSe-Vse and snowflake-shaped copper tetrasulfide (Cu7S4) through ultrasonic stirring. Its preparation process is simple and easy to carry out, highly operable, and has the characteristics of being fast, efficient and stable.

[0028] (2) The loading of Cu7S4 did not affect the crystal structure of ZnSe-Vse. The Cu7S4 / ZnSe-Vse composite material has high crystallinity and purity.

[0029] (3) Under the synergistic effect of photocatalysis and piezoelectric catalysis, the Cu7S4 / ZnSe-Vse composite catalyst exhibits good hydrogen production activity. When the mass of Cu7S4 added to the composite catalyst is 9% of the mass of ZnSe-Vse, the catalyst has the best catalytic performance, which is 84 times and 123 times that of pure ZnSe and Cu7S4 catalysts, respectively, demonstrating its great potential and application value in the field of new energy. Attached Figure Description

[0030] Figure 1 These are the XRD patterns of ZnSe-Vse and Cu7S4;

[0031] Figure 2 The XRD patterns are those of ZnSe-Vse, Cu7S4, and 5-11% Cu7S4 / ZnSe-Vse.

[0032] Figure 3 The images are SEM images (ac) of ZnSe-Vse, Cu7S4, and 9% Cu7S4 / ZnSe-Vse, and EDS images (dg) of 9% Cu7S4 / ZnSe-Vse.

[0033] Figure 4 The LSV curves are for ZnSe, ZnSe-Vse, and 9% Cu7S4 / ZnSe-Vse.

[0034] Figure 5 The EIS plots are for ZnSe, ZnSe-Vse, and 9% Cu7S4 / ZnSe-Vse.

[0035] Figure 6 The graph shows the H2 production performance of ZnSe, ZnSe-Vse, 5-11% Cu7S4 / ZnSe-Vse, and Cu7S4 under piezoelectric-optical conditions.

[0036] Figure 7 The graph shows the H2 production performance of ZnSe, ZnSe-Vse, 5-11%Cu7S4 / ZnSe-Vse, and Cu7S4 under piezoelectric effects only.

[0037] Figure 8 The graph shows the H2 production performance of ZnSe, ZnSe-Vse, 5-11% Cu7S4 / ZnSe-Vse, and Cu7S4 under light-only irradiation.

[0038] Figure 9 This is a diagram showing the cyclic effect of H2 production from 9% Cu7S4 / ZnSe-Vse. Detailed Implementation

[0039] This invention is not limited to the following specific embodiments. Those skilled in the art can implement this invention using various other specific embodiments based on the content disclosed herein. Any modifications or alterations to the design structure and concept of this invention fall within the protection scope of this invention. It should be noted that, in the absence of conflict, the embodiments and features described in these embodiments can be combined with each other. The H2 production efficiency is calculated using the following formula:

[0040]

[0041] R: H2 production rate, unit: μmol / (g·h), V: hydrogen volume, unit: μL, m: catalyst mass, unit: g, t: reaction time, unit: h.

[0042] Example 1

[0043] (1) Dissolve 0.8g of selenium powder in 60mL of distilled water and stir for 0.5h to ensure complete dissolution. Then slowly add 0.8g of sodium borohydride and continue stirring until the solution is clear. Finally, add 3g of Zn(NO3)2. 3)2 ·6H2O, stir for 10 min, then transfer to a reaction vessel with a polytetrafluoroethylene liner, place in an oven at 180℃ for 8 h. After the reaction is complete, cool to room temperature, wash the solid in the reaction vessel three times with deionized water and anhydrous ethanol, dry at 60℃ overnight to obtain ZnSe powder without selenium vacancies, then disperse it in 0.3 mol / L NaOH solution and sonicate for half an hour. After the reaction is complete, dry the separated solid to obtain ZnSe-Vse.

[0044] (2) Dissolve 1 mmol Cu(NO3)2·6H2O in 20 mL of commercially available ethylenediamine and stir for 20 min to disperse it fully. Then add 1 mmol thiourea and stir for 30 min. Then transfer it to a reaction vessel lined with polytetrafluoroethylene and place the reaction vessel in an oven at 120 °C for 2 h. After the reaction is completed, cool to room temperature and wash the solid in the reaction vessel three times with deionized water and anhydrous ethanol. Dry at 60 °C overnight to obtain black Cu7S4 powder.

[0045] (3) Dissolve ZnSe-Vse and Cu7S4 in anhydrous ethanol, sonicate at 240W for 1 h, and stir at 400 r / min for 4 h; filter, wash and dry at room temperature to finally obtain dark green powder, which is the Cu7S4 / ZnSe-Vse composite catalyst rich in selenium vacancies, denoted as 9% Cu7S4 / ZnSe-Vse, where the mass of Cu7S4 is 9% of the mass of ZnSe-Vse.

[0046] Application of 9% Cu7S4 / ZnSe-Vse in catalytic H2 production:

[0047] 2 mg of 9% Cu7S4 / ZnSe-Vse composite catalyst was weighed and added to 18 mL of distilled water. The mixture was sonicated for 0.5 hours to ensure uniform dispersion. Then, 2 mL of a mixed solution of 0.35 M Na2S and 0.25 M Na2SO3 was added as a sacrificial agent. N2 was then passed through the tube for half an hour. Finally, the tube was sealed for 2 hours under ultrasonic (240 W) and simulated sunlight (55 W xenon lamp) conditions. After the experiment, 0.5 mL of gas was extracted from the tube, and the peak area was detected using gas chromatography. The H2 production rate was calculated to be 28.268 mmol / (g·h).

[0048] Example 2

[0049] Compared with Example 1, the difference is that the mass of Cu7S4 added in step (3) is 5% of the mass of ZnSe-Vse, and the other preparation methods are the same as in Example 1. The Cu7S4 / ZnSe-Vse composite catalyst rich in selenium vacancies is denoted as 5% Cu7S4 / ZnSe-Vse.

[0050] The application method is the same as in Example 1. The H2 production rate of the 5% Cu7S4 / ZnSe-Vse prepared in Example 2 is 1.035 mmol / (g·h).

[0051] Example 3

[0052] Compared with Example 1, the difference is that the mass of Cu7S4 added in step (3) is 7% of the mass of ZnSe-Vse, and the other preparation methods are the same as in Example 1. The Cu7S4 / ZnSe-Vse composite catalyst rich in selenium vacancies is denoted as 7% Cu7S4 / ZnSe-Vse.

[0053] The application method is the same as in Example 1. The H2 production rate of the 7% Cu7S4 / ZnSe-Vse prepared in Example 3 is 14.284 mmol / (g·h).

[0054] Example 4

[0055] Compared with Example 1, the difference is that the mass of Cu7S4 added in step (3) is 11% of the mass of ZnSe-Vse, and the other preparation methods are the same as in Example 1. The Cu7S4 / ZnSe-Vse composite catalyst rich in selenium vacancies is denoted as 11% Cu7S4 / ZnSe-Vse.

[0056] The application method is the same as in Example 1. The H2 production rate of the 11% Cu7S4 / ZnSe-Vse prepared in Example 4 is 5.166 mmol / (g·h).

[0057] Example 5

[0058] Compared with Example 1, the difference is that ZnSe-Vse and Cu7S4 are dissolved in deionized water, otherwise the same as in Example 1.

[0059] The application method is the same as in Example 1. The H2 production rate of the 9% Cu7S4 / ZnSe-Vse prepared in Example 5 is 6.802 mmol / (g·h).

[0060] Example 6

[0061] Compared with Example 1, the difference is that the sacrificial agent added in the application method is changed to lactic acid, otherwise it is the same as Example 1.

[0062] The H2 production rate of the 9% Cu7S4 / ZnSe-Vse prepared in Example 6 was 4.711 mmol / (g·h).

[0063] Example 7

[0064] Compared with Example 1, the difference is that ZnSe-Vse and Cu7S4 are dissolved in anhydrous ethanol / water mixed solution (the volume ratio of anhydrous ethanol to water is 8:2), otherwise the same as Example 1.

[0065] The H2 production rate of the 9% Cu7S4 / ZnSe-Vse prepared in Example 7 was 24.025 mmol / (g·h).

[0066] Example 8

[0067] Compared with Example 1, the difference is that ZnSe-Vse and Cu7S4 are dissolved in anhydrous ethanol / water mixed solution (the volume ratio of anhydrous ethanol to water is 5:5), otherwise the same as Example 1.

[0068] The H2 production rate of the 9% Cu7S4 / ZnSe-Vse prepared in Example 8 was 18.264 mmol / (g·h).

[0069] Example 9

[0070] Compared with Example 1, the difference is that the sacrificial agent added in the application method is replaced with triethanolamine, otherwise it is the same as Example 1.

[0071] The H2 production rate of the 9% Cu7S4 / ZnSe-Vse prepared in Example 9 was 7.067 mmol / (g·h).

[0072] Comparative Example 1

[0073] Compared with Example 1, the difference is that "under ultrasonic (240W) and simulated sunlight (55W xenon lamp) conditions" in the application method is changed to "only under ultrasonic (240W) conditions", and the rest is the same as Example 1.

[0074] The H2 production rate of the 9% Cu7S4 / ZnSe-Vse prepared in Comparative Example 1 was 103.39 μmol / (g·h).

[0075] Comparative Example 2

[0076] Compared with Comparative Example 1, the difference is that the mass of Cu7S4 added in step (3) is 5% of the mass of ZnSe-Vse, and the other preparation methods are the same as those in Comparative Example 1.

[0077] The application method was the same as in Comparative Example 1. The H2 production rate of 5% Cu7S4 / ZnSe-Vse prepared in Comparative Example 2 was 41.25 μmol / (g·h).

[0078] Comparative Example 3

[0079] Compared with Comparative Example 1, the difference is that the mass of Cu7S4 added in step (3) is 7% of the mass of ZnSe-Vse, and the other preparation methods are the same as those in Comparative Example 1.

[0080] The application method was the same as that of Comparative Example 1. The H2 production rate of 7% Cu7S4 / ZnSe-Vse prepared in Comparative Example 3 was 76.18 μmol / (g·h).

[0081] Comparative Example 4

[0082] Compared with Comparative Example 1, the difference is that the mass of Cu7S4 added during the catalyst preparation process is 11% of the mass of ZnSe-Vse, and the other preparation methods are the same as those in Comparative Example 1.

[0083] The application method was the same as in Comparative Example 1. The H2 production rate of 11% Cu7S4 / ZnSe-Vse prepared in Comparative Example 2 was 72.10 μmol / (g·h).

[0084] Comparative Example 5

[0085] Compared with Comparative Example 1, the difference is that the application method is changed from only under ultrasonic (240W) conditions to only under simulated sunlight (55W xenon lamp) conditions, while the rest is the same as Comparative Example 1.

[0086] The H2 production rate of the 9% Cu7S4 / ZnSe-Vse composite catalyst prepared in Comparative Example 5 was 8.22 mmol / (g·h).

[0087] Comparative Example 6

[0088] Compared with Comparative Example 5, the difference is that the mass of Cu7S4 added in step (3) is 5% of the mass of ZnSe-Vse, and the other preparation methods are the same as those in Comparative Example 5.

[0089] The H2 production rate of 5% Cu7S4 / ZnSe-Vse prepared by Comparative Example 5 and Comparative Example 6 using the same method was 0.32 mmol / (g·h).

[0090] Comparative Example 7

[0091] Compared with Comparative Example 5, the difference is that the mass of Cu7S4 added in step (3) is 7% of the mass of ZnSe-Vse, and the other preparation methods are the same as those in Comparative Example 5.

[0092] The H2 production rate of the 7% Cu7S4 / ZnSe-Vse prepared in Comparative Example 7 was 5.34 mmol / (g·h).

[0093] Comparative Example 8

[0094] Compared with Comparative Example 5, the difference is that the mass of Cu7S4 added in step (3) is 11% of the mass of ZnSe-Vse, and the other preparation methods are the same as those in Comparative Example 5.

[0095] The H2 production rate of the 11% Cu7S4 / ZnSe-Vse prepared in Comparative Example 8 was 3.82 mmol / (g·h).

[0096] Based on the above-described preferred embodiments of the present invention, and through the foregoing description, those skilled in the art can make various changes and modifications without departing from the inventive concept. The technical scope of this invention is not limited to the contents of the specification, but must be determined according to the scope of the claims.

Claims

1. A method for preparing a Cu7S4 / ZnSe-Vse composite catalyst rich in selenium vacancies, characterized in that, Includes the following steps: ZnSe-Vse and Cu7S4 were dissolved in a solvent, and after sonication and stirring, the mixture was filtered, washed and dried to obtain a Cu7S4 / ZnSe-Vse composite catalyst rich in selenium vacancies. The preparation method of the ZnSe-Vse is as follows: Selenium powder was dissolved in distilled water and stirred for 30 min. Sodium borohydride was then slowly added and stirred until clear. Zn(NO3)2·6H2O was then added and stirred for 10 min. The mixture was then transferred to a reaction vessel with a polytetrafluoroethylene liner and placed in an oven at 180°C for 8 h. After the reaction was completed, the mixture was cooled to room temperature. The solid in the reaction vessel was washed and dried to obtain ZnSe powder without selenium vacancies. The ZnSe powder without selenium vacancies was then dispersed in NaOH solution and sonicated for half an hour. After the reaction was completed, the separated solid was dried to obtain ZnSe-Vse. The preparation method of Cu7S4 is as follows: Cu(NO3)2·6H2O is dissolved in ethylenediamine and stirred for 20 min. Then, thiourea is added and stirred for 30 min. Then, it is transferred to a reaction vessel with a polytetrafluoroethylene liner and placed in an oven at 120°C for 2 h. After the reaction is completed, it is cooled to room temperature. The solid in the reaction vessel is washed and dried to obtain Cu7S4 powder.

2. The method for preparing the selenium-vacancy-rich Cu7S4 / ZnSe-Vse composite catalyst according to claim 1, characterized in that, The mass of Cu7S4 is 5-11% of the mass of ZnSe-Vse.

3. The method for preparing the selenium-vacancy-rich Cu7S4 / ZnSe-Vse composite catalyst according to claim 1, characterized in that, The solvent includes at least one of deionized water and anhydrous ethanol.

4. The method for preparing the selenium-vacancy-rich Cu7S4 / ZnSe-Vse composite catalyst according to claim 1, characterized in that, The ultrasonic power is 240 W, and the ultrasonic time is 1 h; the stirring speed is 400 r / min, and the stirring time is 4 h.

5. The method for preparing the selenium-vacancy-rich Cu7S4 / ZnSe-Vse composite catalyst according to claim 1, characterized in that, The mass ratio of sodium borohydride to selenium powder is 1:1; The mass ratio of selenium powder to Zn(NO3)2·6H2O is 0.8:3.0; The concentration of the NaOH solution is 0.3 mol / L.

6. The method for preparing the selenium-vacancy-rich Cu7S4 / ZnSe-Vse composite catalyst according to claim 1, characterized in that, The molar ratio of Cu(NO3)2·6H2O to thiourea is 1:

1.

7. The application of a selenium-vacancy-rich Cu7S4 / ZnSe-Vse composite catalyst prepared by the method according to any one of claims 1-6 in the catalytic production of H2, characterized in that, The catalyst was added to water and dispersed evenly. Then, a sacrificial agent was added, and N2 was passed through the water to catalyze the production of H2 under ultrasonic and simulated sunlight conditions.

8. The application of the selenium-vacancy-rich Cu7S4 / ZnSe-Vse composite catalyst according to claim 7 in photocatalytic H2 production, characterized in that, The ultrasonic power is 240 W; the simulated sunlight is generated by a xenon lamp with a power of 55 W. The sacrificial agent is one of the following: triethanolamine, lactic acid, a mixed solution of 0.35 M Na2S and 0.25 M Na2SO3.

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