Method for ultrasonic chemical synthesis of multi-defect ternary metal sulfide photocatalyst and application thereof

Abstract

The application relates to a method for ultrasonic chemical synthesis of a multi-defect ternary metal sulfide photocatalyst and application, and belongs to the technical field of photocatalyst preparation. The method is as follows: two kinds of different metal chlorides and thioacetamide are dispersed and dissolved in a mixed solution of a certain volume of ethanol and water in a certain proportion to obtain a precursor solution; the precursor solution is moved to an ultrasonic probe under room temperature to perform ultrasonic treatment; the color and thick consistency of the reaction solution are observed to preliminarily determine the generation of the sulfide; and the ternary metal sulfide photocatalyst is obtained through centrifugation, washing and drying. The technology has the advantages of greenness, high efficiency, batch production, excellent photocatalytic activity, good application prospect and economic benefits.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of photocatalyst preparation, in particular to a method for ultrasonic chemical synthesis of a multi-defect ternary metal sulfide photocatalyst and application thereof. BACKGROUND

[0002] Solar-driven photocatalytic technology is considered as one of the feasible ways to solve the current global energy and environmental crisis. Efficient preparation of high-performance photocatalysts is the key to the popularization and application of photocatalytic technology. Defect engineering can adjust the composition and structure of photocatalysts at the atomic scale and construct active centers, which is a basic method to regulate the photocatalytic performance of materials. The common methods for generating defects in photocatalysts include chemical reduction, heat treatment and external force induction methods such as plasma and laser. These methods require multiple steps, are time-consuming and energy-consuming.

[0003] Ultrasonic wave is a kind of mechanical wave with extremely short wavelength. Under the action of ultrasonic wave, liquid will immediately form bubbles, grow rapidly and break, producing ultrasonic cavitation effect, causing local extreme transient state with heating and cooling rate exceeding 1010K s -1 , temperature exceeding 5000K and pressure exceeding 1000atm. Therefore, the physical and chemical effects of ultrasonic wave can accelerate chemical reactions and have the advantages of simple operation and high efficiency in material synthesis and preparation. Ultrasonic chemistry has been applied in the preparation of metal sulfide photocatalysts. By adjusting the precursor concentration, ultrasonic time and intensity, binary sulfide catalysts with different particle sizes and morphologies are prepared. However, the existing ultrasonic chemistry technology is only used to control the morphology of materials and accelerate the chemical reaction process, and the regulation effect of ultrasonic wave on the defect center of catalytic materials has not been disclosed. SUMMARY

[0004] The present application is an improvement on the application of existing ultrasonic chemistry technology in photocatalyst synthesis, aiming to provide a method for ultrasonic chemical synthesis of multi-defect ternary metal sulfide photocatalyst and application thereof. The method controls the synthesis of metal sulfide photocatalyst at the atomic level, so that it contains rich defect centers, thereby improving the charge separation in photocatalyst and improving the photocatalytic efficiency.

[0005] The method for ultrasonic chemical synthesis of multi-defect ternary metal sulfide photocatalyst comprises the following steps:

[0006] Step 1, dispersing and dissolving two different metal chlorides and thioacetamide in a mixed solution of ethanol and water to obtain a precursor solution A;

[0007] Step 2, preparing product solution B under the action of ultrasonic wave;

[0008] Step 3, centrifuging and washing solution B, and drying to obtain a powder state photocatalyst.

[0009] The two different metal chlorides are any two metal chlorides of cadmium, indium, tin, antimony, zinc, copper, nickel, cobalt, iron or manganese;

[0010] The ultrasonic wave has a frequency of 20 kHz, a power of 200-700 W, a diameter of 6-25 mm, and an on-off time of 5-15 s and 2-5 s, and the total ultrasonic time is 0.5-3 h.

[0011] The molar ratio of the two different metal chlorides and thioacetamide is 1:2:4-1:2:12.

[0012] The volume ratio of the ethanol and water is 1:4-4:1.

[0013] The reaction concentration of the precursor is 0.05-3 mol / L.

[0014] The method can quickly synthesize ternary metal sulfide photocatalysts containing rich sulfur vacancies and uncoordinated electron defect centers.

[0015] The ultrasonic chemical synthesis method can accelerate the homolysis reaction of water under local high temperature and high pressure, and obtain H· active intermediates under the ultrasonic cavitation effect; H· initiates the rapid generation of a large number of S 2- intermediate products; 2- The S intermediate products combine with two different metal ions, orderly assemble, and rapidly form polyhedral block aggregates with metal sulfur vacancies and uncoordinated electrons in a short time, thereby accelerating the controlled preparation of functional metal sulfide photocatalysts; the local high temperature and high pressure not only promote rapid reaction, but also accelerate the kinetic control of atomic assembly, thereby quickly synthesizing ternary metal sulfide photocatalysts with rich sulfur vacancies and uncoordinated electron defect centers.

[0016] The ultrasonic on-off time is controlled to synergize the ultrasonic cavitation effect and thermodynamic stability, thereby rapidly preparing polydefect ternary metal sulfides with a cubic spinel structure and a polyhedral block shape, which have excellent photocatalytic activity in the photocatalytic production of hydrogen peroxide.

[0017] The ultrasonic chemical synthesis method for synthesizing metal sulfide photocatalysts is simple, the raw materials and solvents are cheap and easy to obtain, the preparation cost is low, the method is fast, efficient, green and environmentally friendly, and is suitable for large-scale and efficient controlled preparation of high-quality photocatalysts.

[0018] The ultrasonic chemical synthesis method for synthesizing polydefect ternary metal sulfide photocatalysts has excellent photocatalytic activity in the photocatalytic synthesis of hydrogen peroxide, and has good application prospect and economic benefit. BRIEF DESCRIPTION OF DRAWINGS

[0019] Figure 1 Reaction mechanism diagram for synthesizing ternary metal sulfide by ultrasonic chemical method of Example 1.

[0020] Figure 2 X-ray diffraction pattern for synthesizing ternary metal sulfide by ultrasonic chemical method.

[0021] Figure 3 Electron microscope photo for synthesizing ternary metal sulfide by ultrasonic chemical method.

[0022] Figure 4 Electron paramagnetic resonance spectrum for synthesizing ternary metal sulfide by ultrasonic chemical method and solvothermal method.

[0023] Figure 5 Hydrogen peroxide yield graph for synthesizing ternary metal sulfide by ultrasonic chemical method.

[0024] Figure 6 Hydrogen peroxide reaction time-hydrogen peroxide concentration relationship graph for synthesizing ternary metal sulfide by ultrasonic chemical method. DETAILED DESCRIPTION

[0025] The application will be further described in detail below with examples. The following examples will help those skilled in the art to further understand the application, but do not limit the application in any form. It should be pointed out that those skilled in the art can make several modifications and improvements without departing from the concept of the application, and these all belong to the protection scope of the application.

[0026] Example 1: Method for synthesizing multi-defect ZnIn2S4 photocatalyst by ultrasonic chemical method, the specific steps are as follows:

[0027] S1, weigh 1.36 g (10 mmol) of zinc chloride, 4.42 g (20 mmol) of indium chloride and 4.50 g (60 mmol) of thioacetamide in a 250 ml beaker, add 50 ml of ethanol and 50 ml of deionized water, mix to obtain precursor solution A.

[0028] S2, place solution A under a 6 mm diameter amplitude rod for ultrasonic treatment, the ultrasonic frequency is 20 kHz, the ultrasonic power is 500 W, alternately open for 5 s and close for 2 s, the total ultrasonic time is 2 h to obtain product solution B.

[0029] S3, centrifugal wash solution B at a speed of 6000 rpm, centrifugal wash with deionized water and ethanol for 4 times respectively, dry at 65℃ for 12 h to obtain light yellow powder.

[0030] The ternary metal sulfide prepared in this example is subjected to corresponding detection. The X-ray diffraction is as follows: Figure 2ZnIn2S4with cubic spinel structure (#JCPDS card number: 65-2023) is shown. The scanning electron microscope photos are shown in Figure 2. Figure 3 As shown in Figure 2, it can be seen that the ZnIn2S4prepared by the ultrasonic chemical method has a polyhedral block-like micro-morphology. From the electron paramagnetic resonance spectrum characterization analysis, it can be seen that the ZnIn2S4contains both sulfur vacancies and unpaired electron defect sites, which is significantly different from the ternary metal sulfides prepared by the solvothermal method and the binary metal sulfide photocatalysts prepared by the ultrasonic chemical method reported in the prior art. Figure 4

[0031] The ZnIn2S4photocatalyst obtained in this embodiment is applied to the photocatalytic production of hydrogen peroxide, and the specific steps are as follows:

[0032] S1, 5mg of ZnIn2S4is weighed in a 15ml quartz reaction tube, 9ml of deionized water and 1ml of benzyl alcohol are added to obtain a two-phase solution.

[0033] S2, the two-phase solution is ultrasonically cleaned for 20min by using an ultrasonic cleaning machine to fully disperse, and then high-purity oxygen is bubbled for 30min to keep it in an oxygen-saturated solution.

[0034] S3, oxygen is continuously introduced to maintain an oxygen-rich environment, and the reaction is stirred under simulated sunlight irradiation. Every 20min, the sample is taken, the supernatant is collected by centrifugation, the concentration of hydrogen peroxide is detected by using the DPD-POD method, and the yield is calculated.

[0035] Figure 5 The photocatalytic synthesis of hydrogen peroxide by the ZnIn2S4ultrasonic chemical synthesis in Example 1 has a yield of hydrogen peroxide as high as 21600umol·g -1 ·h -1 , which is significantly higher than the photocatalytic production of hydrogen peroxide by most of the organic, inorganic, hybrid and other photocatalysts reported in the prior art.

[0036] Example 2: Method for synthesizing a multi-defect MgIn2S4photocatalyst by an ultrasonic chemical method, and the specific steps are as follows:

[0037] S1, 0.95g (10mmol) of magnesium chloride, 4.42g (20mmol) of indium chloride and 6.0g (80mmol) of thioacetamide are weighed in a 250ml beaker, 50ml of ethanol and 50ml of deionized water are added to obtain a precursor solution A.

[0038] S2, the solution A is placed under a 6mm diameter amplitude rod for ultrasonic treatment, the ultrasonic frequency is 20kHz, the ultrasonic power is 500W, the ultrasonic treatment is alternately turned on for 10s and turned off for 2s, and the total ultrasonic treatment time is 2h to obtain a product solution B.

[0039] ​S3. Solution B was centrifuged and washed at 6000 rpm, and then washed four times with deionized water and ethanol. The solution was dried at 65°C for 12 h to obtain a bright yellow powder.

[0040] The ternary metal sulfide prepared in this embodiment was subjected to corresponding tests. The X-ray diffraction pattern is shown below. Figure 2 As shown, this is a cubic spinel structure MgIn2S4 (#JCPDS card number: 31-0792), and the scanning electron microscope image is as follows. Figure 3 As shown, MgIn2S4 prepared by ultrasonic chemical method has a polyhedral bulk microstructure.

[0041] The MgIn2S4 photocatalyst synthesized by the ultrasonic chemical method in this embodiment was applied to the photocatalytic production of hydrogen peroxide. The specific steps are as follows:

[0042] S1. Weigh 5 mg of MgIn2S4 into a 15 ml quartz reaction tube, add 9 ml of deionized water and 1 ml of benzyl alcohol to obtain a two-phase solution.

[0043] S2, the two-phase solution is ultrasonically cleaned for 20 minutes to fully disperse it, and then bubbled with high-purity oxygen for 30 minutes to keep it in an oxygen-saturated solution.

[0044] S3, oxygen is continuously introduced to maintain an oxygen-rich environment, and the reaction is stirred under simulated sunlight. Samples are taken every 20 minutes, the supernatant is collected by centrifugation, the hydrogen peroxide concentration is detected by DPD-POD method, and the yield is calculated.

[0045] Figure 5 The photocatalytic synthesis of hydrogen peroxide from MgIn2S4 using ultrasonic chemical synthesis of this invention yielded a yield of 3520.9 μmol·g. -1 ·h -1 .

[0046] Example 3: A method for synthesizing multi-defect NiIn2S4 photocatalysts using sonicochemical method, the specific steps of which are as follows:

[0047] S1. Weigh 1.30 g (10 mmol) of nickel chloride, 4.42 g (20 mmol) of indium chloride and 4.50 g (60 mmol) of thioacetamide into a 250 ml beaker, add 50 ml of ethanol and 50 ml of deionized water to obtain precursor solution A.

[0048] S2, Solution A is placed under an amplitude transformer with a diameter of 6 mm for ultrasonication. The ultrasonic frequency is 20 kHz and the ultrasonic power is 500 W. The ultrasonic frequency is alternately turned on for 10 seconds and off for 5 seconds. After a total ultrasonic time of 2 hours, product solution B is obtained.

[0049] S3, solution B was centrifuged and washed at 6000 rpm, and then washed four times with deionized water and ethanol. The solution was dried at 65℃ for 12 h to obtain a gray-green powder.

[0050] The ternary metal sulfide prepared in this embodiment was subjected to corresponding tests. The X-ray diffraction pattern is shown below. Figure 2 As shown, this is a cubic spinel structure NiIn2S4 (#JCPDS card number: 70-2900), and the scanning electron microscope image is as follows. Figure 3 As shown, CoIn2S4 prepared by ultrasonic chemical method has a polyhedral bulk microstructure.

[0051] The NiIn2S4 photocatalyst synthesized by the ultrasonic chemical method in this embodiment was applied to the photocatalytic production of hydrogen peroxide. The specific steps are as follows:

[0052] S1. Weigh 5 mg of NiIn2S4 into a 15 ml quartz reaction tube, add 9 ml of deionized water and 1 ml of benzyl alcohol to obtain a two-phase solution.

[0053] S2, the two-phase solution is ultrasonically dispersed for 20 minutes using an ultrasonic cleaner, and then bubbled with high-purity oxygen for 30 minutes to keep it in an oxygen-saturated solution.

[0054] S3, oxygen is continuously introduced to maintain an oxygen-rich environment, and the reaction is stirred under simulated sunlight. Samples are taken every 20 minutes, the supernatant is collected by centrifugation, the hydrogen peroxide concentration is detected by DPD-POD method, and the yield is calculated.

[0055] Figure 5 The photocatalytic synthesis of hydrogen peroxide from NiIn2S4 using ultrasonic chemical synthesis of this invention achieves a yield as high as 2218.6 μmol·g. -1 ·h -1 .

[0056] Example 4: A method for synthesizing multi-defect CoIn2S4 photocatalysts using sonicochemical method, the specific steps of which are as follows:

[0057] S1. Weigh 1.30 g (10 mmol) cobalt chloride, 4.42 g (20 mmol) indium chloride and 0.30 g (40 mmol) thioacetamide into a 250 ml beaker, add 50 ml ethanol and 50 ml deionized water to obtain precursor solution A.

[0058] S2. Solution A was placed under a cell disruptor with an amplitude transformer diameter of 6 mm for sonication at a frequency of 20 kHz. The sonication was performed alternately for 10 seconds on and 4 seconds off, with a total sonication time of 2 hours, to obtain solution B.

[0059] S3 was centrifuged and washed at 6000 rpm, then washed four times with deionized water and ethanol, and dried at 65℃ for 12 h to obtain a gray-green powder.

[0060] The ternary metal sulfide prepared in this embodiment was subjected to corresponding tests. The X-ray diffraction pattern is shown below. Figure 2 As shown, this is a cubic spinel structure of CoIn2S4 (#JCPDS card number: 31-0421), and the scanning electron microscope image is as follows. Figure 3 As shown, CoIn2S4 prepared by ultrasonic chemical method has a polyhedral bulk microstructure.

[0061] In this embodiment, the CoIn2S4 photocatalyst synthesized by ultrasonic chemistry is applied to the photocatalytic production of hydrogen peroxide. The specific steps are as follows:

[0062] S1. Weigh 5 mg of NiIn2S4 into a 15 ml quartz reaction tube, add 9 ml of deionized water and 1 ml of benzyl alcohol to obtain a two-phase solution.

[0063] S2, the two-phase solution is ultrasonically dispersed for 20 minutes using an ultrasonic cleaner, and then bubbled with high-purity oxygen for 30 minutes to keep it in an oxygen-saturated solution.

[0064] S3, oxygen is continuously introduced to maintain an oxygen-rich environment, and the reaction is stirred under simulated sunlight. Samples are taken every 20 minutes, the supernatant is collected by centrifugation, the hydrogen peroxide concentration is detected by DPD-POD method, and the yield is calculated.

[0065] Figure 5 The photocatalytic synthesis of hydrogen peroxide from CoIn2S4 using ultrasonic chemical synthesis of this invention yielded a yield of 1993.7 μmol·g. -1 ·h -1 .

Claims

1. A multi-defect ternary metal sulfide photocatalyst synthesized by ultrasonic chemical synthesis is used for photocatalytic production of hydrogen peroxide, wherein the photocatalyst is any one of ZnIn2S4, MgIn2S4, Niln2S4, or Coln2S4; the synthesis method includes the following steps: Step 1: Disperse and dissolve two different metal chlorides and thioacetamide in a mixed solution of ethanol and water to obtain precursor solution A; Step 2: Prepare product solution B by subjecting precursor solution A to ultrasound. Step 3: Centrifuge and wash solution B, then dry to obtain a pale yellow powder; The ultrasound uses an ultrasonic frequency of 20 kHz; ultrasonic power of 200-700 W; amplitude transformer diameter of 6-25 mm; ultrasonic on-off alternation time of 5-15 s on and 2-5 s off, with a total ultrasound time of 2-3 h. The molar ratio of the two different metal chlorides and thioacetamide is 1:2:4 to 1:2:12; The volume ratio of ethanol to water is 1:4 to 4:1; The reaction concentration of the precursor is 0.05-3 mol / L.

2. The ternary metal sulfide photocatalyst as described in claim 1 is applied to the photocatalytic production of hydrogen peroxide, characterized in that, The specific steps are as follows: S1, deionized water and benzyl alcohol are added to a ternary metal sulfide photocatalyst to obtain a two-phase solution; S2, the two-phase solution is ultrasonically cleaned to fully disperse it, and then high-purity oxygen is bubbled to keep it in a solution saturated with molecular oxygen; S3 continuously introduces oxygen to maintain an oxygen-rich environment, and under simulated sunlight, it stirs and reacts to produce hydrogen peroxide.

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