Preparation methods and applications of indium sulfide photocatalysts with specific vacancies

Abstract

This invention proposes a method for preparing and applying an indium sulfide photocatalytic material with specific vacancies. The method involves forming a first solution with ethanol and deionized water; dissolving InCl3·4H2O and thioacetamide, or InCl3·4H2O, thioacetamide, and hexamethylenetetramine, in the first solution by stirring; obtaining a clear solution; reacting the clear solution at a constant temperature; cooling after the reaction; and collecting the product by centrifugation; washing the product; and drying it at a constant temperature; finally, obtaining the photocatalytic material with specific vacancies. This invention introduces vacancies into In2S3, thereby regulating the surface active sites, enhancing its light utilization efficiency and the separation and transfer ability of photogenerated carriers, and improving the photocatalytic activity of N2 to NH3 reduction.

Description

Technical Field

[0001] This invention relates to the field of photocatalytic material preparation, and particularly to a method for preparing and applying an indium sulfide photocatalytic material with specific vacancies. Background Technology

[0002] Ammonia (NH3) is an irreplaceable chemical substance in the production of agricultural fertilizers and synthetic fibers, and is crucial for societal production and industrial processes. Currently, the Haber-Bosch process remains the primary method for ammonia synthesis, but its high-temperature (>673 K) and high-pressure (>200 bar) reaction conditions are extremely unfriendly to both safety and the environment. Against this backdrop, developing sustainable and energy-efficient nitrogen fixation methods is crucial for addressing energy and environmental sustainability challenges. Utilizing solar energy to drive the conversion of N2 to NH3 under mild conditions is a promising green alternative to traditional Haber-Bosch chemistry. However, the energy required to break the N≡N bond is as high as 940.95 kJ·mol⁻¹. -1 This makes it very difficult to convert N2 molecules into a usable form. Furthermore, photocatalysts themselves face challenges such as light absorption rate, photogenerated charge separation and transfer efficiency, and conversion efficiency. Therefore, it is necessary to rationally design photocatalysts to promote the efficient conversion of N2 into NH3.

[0003] Among visible-light-responsive photocatalysts, metal sulfides have been widely reported for use in environmental and energy fields due to their unique properties, high abundance, and simple, low-cost synthesis processes. Among numerous metal sulfides, In₂S₃ stands out as a promising photocatalyst due to its several advantages. First, In₂S₃ possesses a favorable band gap (2.0-2.4 eV), enabling it to capture a large portion of the solar spectrum, allowing for efficient light absorption and the formation of photogenerated electron-hole pairs. Second, In₂S₃ exhibits a relatively negative conduction band and a relatively positive valence band, along with excellent charge transport capabilities, allowing photoexcited charge carriers to be effectively transferred to the catalyst surface to participate in redox reactions while maintaining high redox potential.

[0004] While the narrow bandgap of In₂S₃ grants it a wide light absorption range, this also typically leads to rapid recombination of photogenerated electrons and holes within the catalyst. Studies have shown that due to the high recombination rate of photogenerated carriers, only about 10% of the photoexcited electrons in In₂S₃ are available for photocatalytic reduction reactions. Furthermore, due to the high recombination rate of photogenerated carriers, only about 10% of the photoexcited electrons in In₂S₃ are available for photocatalytic reduction reactions. 2- Ions under oxidizing conditions (such as photogenerated holes, photogenerated carriers mediated by various free radicals, etc.) will be oxidized to atoms S (S 0Leaching leads to widespread photocorrosion of metal sulfides, severely impacting photocatalytic efficiency and long-term stability. Simultaneously, current photocatalytic processes generally exhibit low reaction efficiencies, becoming a bottleneck for the practical application of photocatalysts. Therefore, improving the photocatalytic activity, efficiency, and stability of In₂S₃ is of great significance. Summary of the Invention

[0005] In view of the above, the main objective of this invention is to provide a method for preparing and applying an indium sulfide photocatalytic material with specific vacancies, so as to solve the above-mentioned technical problems.

[0006] This invention proposes a method for preparing an indium sulfide photocatalytic material with specific vacancies, the method comprising the following steps:

[0007] Ethanol and deionized water are used to form the first solution;

[0008] InCl3·4H2O and thioacetamide, or InCl3·4H2O, thioacetamide and hexamethylenetetramine, are placed in the first solution and stirred to dissolve. After stirring, a clear solution is obtained.

[0009] The clear solution was reacted at a constant temperature. After the reaction was completed, it was cooled and then centrifuged to collect the product.

[0010] The obtained product was washed and then dried at a constant temperature. After drying, a photocatalytic material with specific vacancies was obtained.

[0011] The present invention also proposes an application of an indium sulfide photocatalytic material with specific vacancies. The photocatalytic material prepared by the above-mentioned preparation method of indium sulfide photocatalytic material with specific vacancies is used for photocatalytic reduction of N2 to NH3.

[0012] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0013] This invention introduces vacancies into In2S3 to regulate the surface active sites, thereby enhancing its light utilization and the separation and transfer capabilities of photogenerated carriers. This allows for the fixation of N2 in the air, its conversion into NH3 under illumination, and an improvement in the photocatalytic reduction of N2 to NH3 activity, which is beneficial to the advancement and development of catalytic materials.

[0014] Additional aspects and advantages of the invention will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by means of embodiments of the invention. Attached Figure Description

[0015] Figure 1 XRD patterns of different samples;

[0016] Figure 2 Here are the SEM and TEM images of the sample;

[0017] Figure 3 The yield graph of NH3 for different samples under light source irradiation;

[0018] Figure 4 The graph shows the yield of NH3 in the sample under different conditions;

[0019] Figure 5 The UV diffuse reflectance maps are for different samples;

[0020] Figure 6 The photocurrent response diagram of the sample;

[0021] Figure 7 The impedance diagram of the sample;

[0022] Figure 8 Photoluminescence spectra of different samples. Detailed Implementation

[0023] Embodiments of the present invention are described in detail below. Examples of these embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the present invention, and should not be construed as limiting the present invention.

[0024] These and other aspects of the embodiments of the present invention will become clear from the following description and accompanying drawings. In these descriptions and drawings, some specific embodiments of the present invention are specifically disclosed to illustrate some ways of implementing the principles of the embodiments of the present invention; however, it should be understood that the scope of the embodiments of the present invention is not limited thereto.

[0025] Example 1

[0026] This embodiment discloses a method for preparing an indium sulfide photocatalytic material with specific vacancies, the method comprising the following steps:

[0027] Prepare the first solution by mixing 15 mL of ethanol and 15 mL of deionized water;

[0028] 0.2346 g of InCl3·4H2O and 1202 g of thioacetamide were placed in the first solution and stirred for 30 min to obtain a clear solution;

[0029] The clear solution was reacted at 160 °C for 24 h, then naturally cooled to room temperature, and the product was collected by centrifugation.

[0030] The obtained product was washed three times with deionized water and then three times with anhydrous ethanol. After washing, it was dried at 80 °C for 12 h to obtain In2S3 (vacancy-free) photocatalytic material.

[0031] Example 2

[0032] This embodiment discloses a method for preparing an indium sulfide photocatalytic material with specific vacancies, the method comprising the following steps:

[0033] Prepare the first solution by mixing 10 mL of ethanol and 10 mL of deionized water;

[0034] 0.2 g of InCl3·4H2O and 1000 g of thioacetamide were placed in the first solution and stirred for 20 min to obtain a clear solution;

[0035] The clear solution was reacted at 140℃ for 20 hours, then naturally cooled to room temperature, and the product was collected by centrifugation.

[0036] The obtained product was washed once with deionized water and then once with anhydrous ethanol. After washing, it was dried at 60 °C for 10 h to obtain In2S3 (vacancy-free) photocatalytic material.

[0037] Example 3

[0038] This embodiment discloses a method for preparing an indium sulfide photocatalytic material with specific vacancies, the method comprising the following steps:

[0039] Prepare the first solution by mixing 20 mL of ethanol and 20 mL of deionized water;

[0040] 0.4 g of InCl3·4H2O and 1300 g of thioacetamide were placed in the first solution and stirred for 25 min to obtain a clear solution;

[0041] The clear solution was reacted at 150 °C for 22 h, then naturally cooled to room temperature, and the product was collected by centrifugation.

[0042] The obtained product was washed five times with deionized water and then five times with anhydrous ethanol. After washing, it was dried at 70 °C for 14 h to obtain In2S3 (vacancy-free) photocatalytic material.

[0043] Example 4

[0044] This embodiment discloses a method for preparing an indium sulfide photocatalytic material with specific vacancies, the method comprising the following steps:

[0045] Prepare the first solution by mixing 15 mL of ethanol and 15 mL of deionized water;

[0046] 0.3000g of InCl3·4H2O and 0.2346g of thioacetamide were placed in the first solution and stirred for 30 minutes to obtain a clear solution;

[0047] The clear solution was reacted at 160 °C for 24 h, then naturally cooled to room temperature, and the product was collected by centrifugation.

[0048] The obtained product was washed three times with deionized water and then three times with anhydrous ethanol. After washing, it was dried at 80 °C for 12 h to obtain In2S3-V. S (Sulfur vacancy) photocatalytic materials.

[0049] Example 5

[0050] This embodiment discloses a method for preparing an indium sulfide photocatalytic material with specific vacancies, the method comprising the following steps:

[0051] Prepare the first solution by mixing 10 mL of ethanol and 10 mL of deionized water;

[0052] 0.2 g of InCl3·4H2O and 0.2 g of thioacetamide were placed in the first solution and stirred for 20 min to obtain a clear solution;

[0053] The clear solution was reacted at 140 °C for 20 h, then naturally cooled to room temperature, and the product was collected by centrifugation.

[0054] The obtained product was washed once with deionized water and then once with anhydrous ethanol. After washing, it was dried at 60 °C for 10 h to obtain In2S3-V. S (Sulfur vacancy) photocatalytic materials.

[0055] Example 6

[0056] This embodiment discloses a method for preparing an indium sulfide photocatalytic material with specific vacancies, the method comprising the following steps:

[0057] Prepare the first solution by mixing 20 mL of ethanol and 20 mL of deionized water;

[0058] 0.4 g of InCl3·4H2O and 0.4 g of thioacetamide were placed in the first solution and stirred for 25 min to obtain a clear solution;

[0059] The clear solution was reacted at 150 °C for 22 h, then naturally cooled to room temperature, and the product was collected by centrifugation.

[0060] The obtained product was washed five times with deionized water and then five times with anhydrous ethanol. After washing, it was dried at 70 °C for 14 h to obtain In2S3-V. S (Sulfur vacancy) photocatalytic materials.

[0061] Example 7

[0062] This embodiment discloses a method for preparing an indium sulfide photocatalytic material with specific vacancies, the method comprising the following steps:

[0063] Prepare the first solution by mixing 15 mL of ethanol and 15 mL of deionized water;

[0064] 0.2346 g of InCl3·4H2O, 1202 g of thioacetamide and 0.3005 g of hexamethylenetetramine were placed in the first solution and stirred for 30 min to obtain a clear solution.

[0065] The clear solution was reacted at 160 °C for 24 h, then naturally cooled to room temperature, and the product was collected by centrifugation.

[0066] The obtained product was washed three times with deionized water and then three times with anhydrous ethanol. After washing, it was dried at 80 °C for 12 h to obtain In2S3-V. In (Indium vacancy) photocatalytic materials.

[0067] Example 8

[0068] This embodiment discloses a method for preparing an indium sulfide photocatalytic material with specific vacancies, the method comprising the following steps:

[0069] Prepare the first solution by mixing 10 mL of ethanol and 10 mL of deionized water;

[0070] 0.2 g of InCl3·4H2O, 1000 g of thioacetamide and 0.2 g of hexamethylenetetramine were placed in the first solution and stirred for 20 min to obtain a clear solution;

[0071] The clear solution was reacted at 140 °C for 20 h, then naturally cooled to room temperature, and the product was collected by centrifugation.

[0072] The obtained product was washed once with deionized water and then once with anhydrous ethanol. After washing, it was dried at 60 °C for 10 h to obtain In2S3-V. In (Indium vacancy) photocatalytic materials.

[0073] Example 9

[0074] This embodiment discloses a method for preparing an indium sulfide photocatalytic material with specific vacancies, the method comprising the following steps:

[0075] Prepare the first solution by mixing 20 mL of ethanol and 20 mL of deionized water;

[0076] 0.4 g of InCl3·4H2O, 1300 g of thioacetamide and 0.4 g of hexamethylenetetramine were placed in the first solution and stirred for 25 min to obtain a clear solution.

[0077] The clear solution was reacted at 150 °C for 22 h, then naturally cooled to room temperature, and the product was collected by centrifugation.

[0078] The obtained product was washed five times with deionized water and then five times with anhydrous ethanol. After washing, it was dried at 70 °C for 14 h to obtain In2S3-V. In (Indium vacancy) photocatalytic materials.

[0079] Example 10

[0080] This embodiment discloses the application of an indium sulfide photocatalytic material with specific vacancies. The photocatalytic material prepared by the above-described method for preparing indium sulfide photocatalytic material with specific vacancies is used for photocatalytic reduction of N2 to NH3.

[0081] To verify the performance of the indium sulfide photocatalyst material with specific vacancies prepared in this invention for photocatalytic N2 reduction, the results prepared in Examples 1, 2, and 3 were used for verification. The result of Example 1 is denoted as In2S3, and the result of Example 4 is denoted as In2S3-V. S The preparation result of Example 7 is denoted as In2S3-V In The details are as follows:

[0082] Photocatalytic N2 reduction experiments were conducted at room temperature in a quartz reaction vessel with a top illumination window. Typically, 50 mg of the prepared photocatalyst powder was added to 100 mL of deionized water and dispersed by sonication for 5 min. The resulting photocatalyst suspension was continuously bubbled into the mixed solution at a flow rate of 60 mL / min for 30 min while stirring in the dark to remove air from the suspension and obtain an N2-saturated aqueous suspension. A 300 W xenon lamp was used as the light source to illuminate the reactor, while circulating cooling water was used to maintain the temperature of the reaction solution at a constant 20 °C. The reaction solution was collected every 30 min, and then the catalyst was removed by centrifugation, with the supernatant collected for later use.

[0083] The amount of ammonia produced was determined using the indophenol blue method. 2 mL of a 1 M NaOH solution containing 5% (w / w) salicylic acid and 5% (w / w) sodium citrate, 1 mL of 0.05 M NaClO, and 0.2 mL of a 1% (w / w) C5FeN6Na2O (sodium nitroprusside) aqueous solution were added to 2 mL of the reaction solution. The solution was then left to stand in darkness for 2 h, and the absorption spectrum was measured using a UV-Vis spectrophotometer. The formation of indophenol blue was determined by absorbance at 650 nm, and the yield was calibrated by preparing a standard sample of ammonium chloride at a specific concentration.

[0084] Figure 1 XRD patterns for each sample, In2S3-V S In2S3-V In The In2S3 exhibits distinct characteristic diffraction peaks at 2θ = 27.43°, 33.23°, and 47.71°, corresponding to the (311), (400), and (440) crystal planes of In2S3 (JCPDS PDF#84-1385), respectively. No peaks corresponding to other substances appeared in the XRD patterns of any of the samples, indicating that the synthesized samples are of high purity. It is noteworthy that for In2S3-V... S In2S3-V In The presence of structural defects led to a decrease in the crystallinity of the sample.

[0085] Figure 2 The images show SEM and TEM images of the sample. In2S3 exists in the form of irregularly stacked nanosheets. Figure 2 a and Figure 2 (b) in the text. Further through HR-TEM ( Figure 2 c) The clear and complete lattice fringes of In2S3 were observed, proving that there are essentially no atomic vacancies in its lattice. The lattice fringe spacings of 0.27 nm and 0.19 nm are attributed to the (400) and (440) crystal planes of In2S3, respectively. In2S3-V S It consists of nanoflower-shaped spheres formed by the aggregation of nanosheets. Figure 2 d and Figure 2 (e) in the HR-TEM diagram. Figure 2 In f), lattice fringes with a spacing of 0.27 nm are attributed to the (400) crystal plane of In2S3, and significant lattice distortion was found, which is attributed to In2S3-V. S S-rich vacancies in the sample ( Figure 2 f in the text. In2S3-VIn is composed of microspheres made up of nanosheets (f). Figure 2 g and Figure 2 h in In2S3-V InIn HR-TEM ( Figure 2 In the diagram, lattice fringes with a spacing of 0.38 nm (i) belong to the (220) plane of In2S3. Furthermore, magnifying the area within the red box reveals clear lattice gaps in the area marked by the blue circle, and the intensity distribution on line 1 also shows significant intensity deficiencies, corresponding to In2S3-V... In In vacancies in the sample ( Figure 2 (i)

[0086] like Figure 3 and Figure 4 As shown, after a reaction time of 150 min, the NH4 content of the In2S3 sample... + The generation rate is very low; after introducing S vacancies, In2S3-V S NH4 + Production has been improved to some extent, while the introduction of In vacancies in In2S3-V In Its nitrogen fixation activity is significantly higher than the former two. Figure 3 The image shows NH4 + Average yield, In2S3-V In NH4 in the full spectrum + The yield was 67.23 μmol / g / h, significantly higher than that of In₂S₃ (2.18 μmol / g / h) and In₂S₃-V. S (11.55 μmol / g / h). Simultaneously, experiments were conducted to control the reaction conditions, from... Figure 4 It can be seen from this that: when in In2S3-V In When La atoms were photodeposited onto the sample, the photocatalytic nitrogen fixation activity decreased significantly, indicating that In vacancies played an important role in the reaction. Furthermore, under air conditions, NH4... + The decrease in yield and the almost absence of NH4 under argon conditions + The generation of NH4 in the reaction system + It originates from N2. Furthermore, when the reaction is carried out without a catalyst and under dark conditions, almost no NH4 is produced. + generate.

[0087] Figure 5 The UV-vis-DRS spectra of the samples show that all three samples exhibit some absorption of visible light, and In2S3-V S and In2S3-V In A significant redshift occurred relative to the absorption of In2S3, indicating that the introduction of vacancies can enhance the light absorption of the sample and make better use of visible light.

[0088] Figure 6 and Figure 7The photocurrent response and impedance diagrams of the prepared catalysts are shown. The photocurrent density-time curve represents the generation of photogenerated charges in the semiconductor photocatalyst, while a lower photocurrent density indicates a greater probability of recombination between photogenerated electrons and holes. Figure 6 As shown, In2S3-V In The highest photocurrent response intensity indicates that it possesses the best ability to separate photogenerated charges, enabling more efficient separation and transfer of photogenerated electrons / holes. Electrochemical impedance spectroscopy further investigated the charge transfer efficiency of the prepared samples. The radius of curvature of the curve in electrochemical impedance spectroscopy directly reflects the magnitude of resistance to charge transfer. Figure 7 As shown, In2S3-V In The smallest radius of curvature indicates that it has the smallest electrochemical impedance and the lowest resistance to photogenerated carrier transfer, and the highest charge separation efficiency, which is consistent with the photocurrent test results.

[0089] Figure 8 The image shows the photoluminescence spectrum of the sample. The recombination of photogenerated electrons and holes releases energy in the form of light and heat, producing fluorescence. Therefore, for photocatalysis, good catalytic effect corresponds to high separation efficiency of photogenerated charges, i.e., low photoluminescence intensity. As can be seen from the image, under light excitation at 551 nm wavelength, In₂S₃, In₂S₃-V… S and In2S3-V In Emission occurred at a wavelength of approximately 830 nm. Among them, In₂S₃-V S and In2S3-V In The luminescence intensity of the sample is lower than that of In2S3, indicating that the introduction of S vacancies and In vacancies can reduce the recombination rate of photogenerated carriers in the sample, thereby promoting its photocatalytic activity.

[0090] In the description of this specification, references to terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0091] The embodiments described above are merely illustrative of several implementations of the present invention, and while the descriptions are specific and detailed, they should not be construed as limiting the scope of the present invention. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these modifications and improvements all fall within the scope of protection of the present invention. Therefore, the scope of protection of this patent should be determined by the appended claims.

Claims

1. A method for preparing an indium sulfide photocatalytic material with specific vacancies, characterized in that, The method includes the following steps: The first solution is prepared by mixing ethanol and deionized water; InCl3·4H2O, thioacetamide, and hexamethylenetetramine were placed in a first solution and stirred to dissolve. After stirring, a clear solution was obtained. The mass of InCl3·4H2O added was 0.2~0.4 g, the mass of thioacetamide was 1000~1300 g, and the mass of hexamethylenetetramine was 0.2~0.4 g. The clear solution was reacted at a constant temperature. After the reaction was completed, it was cooled and then centrifuged to collect the product. The obtained product was washed and then dried at a constant temperature. After drying, an indium sulfide photocatalytic material with specific vacancies was obtained. Wherein, the indium sulfide photocatalyst material with specific vacancies is In2S3-V rich in indium vacancies. In When used for photocatalytic reduction of N2 to NH3, the photocatalytic reduction rate of N2 to NH3 reached 67.23 μmol·g. -1 h -1 .

2. The method for preparing indium sulfide photocatalyst material with specific vacancies according to claim 1, characterized in that, During the process of forming the first solution from ethanol and deionized water, the volume of ethanol is 10-20 mL and the volume of deionized water is 10-20 mL; during the stirring and dissolution process, the stirring time is 20-30 min.

3. The method for preparing indium sulfide photocatalyst material with specific vacancies according to claim 2, characterized in that, During the constant-temperature reaction of the clear solution, the temperature is 140~160 ℃ and the reaction time is 20~24h; during the cooling process, natural cooling is used to cool to room temperature.

4. The method for preparing indium sulfide photocatalyst material with specific vacancies according to claim 3, characterized in that, During the washing process of the obtained product, it was washed with deionized water and anhydrous ethanol in sequence, with each washing being 1 to 5 times.

5. The method for preparing indium sulfide photocatalyst material with specific vacancies according to claim 4, characterized in that, During the constant temperature drying process, the temperature is 60~80 ℃ and the drying time is 10~14h.

6. The application of an indium sulfide photocatalyst material with specific vacancies, characterized in that, An indium sulfide photocatalytic material prepared by the preparation method of indium sulfide photocatalytic material with specific vacancies according to any one of claims 1 to 5, wherein the indium sulfide photocatalytic material is used for photocatalytic reduction of N2 to NH3.

Images