Rare earth eu doped in2o3 / in2s3 heterojunction photocatalytic material, preparation method and application

Abstract

The application provides a rare earth Eu-doped In2O3 / In2S3 heterojunction photocatalytic material, a preparation method and application, the method comprises the following steps: synthesizing a MIL-68(In) precursor through a hydrothermal method to obtain an In2O3 hollow microtubular photocatalyst; growing In2S3 nanosheets on the In2O3 hollow microtubular photocatalyst through an oil bath method to obtain an In2O3 / In2S3 heterojunction photocatalyst; doping a rare earth element Eu in the matrix lattice of the In2O3 / In2S3 heterojunction photocatalyst to obtain a heterojunction photocatalytic material; the rare earth Eu-doped In2O3 / In2S3 hollow tubular heterojunction (Eu-IOIS) composite photocatalytic material constructed by the application has a large specific surface area, which is beneficial to expose more reaction active sites; the strong built-in electric field of the S-type heterojunction of In2O3 / In2S3 and the effect of the electron transport bridge of the rare earth Eu single atom jointly improve the separation and transfer of photo-generated charges. Therefore, the Eu-IOIS exhibits enhanced photocatalytic N2 reduction and coupling CH3OH oxidation performance to synthesize urea.

Description

TECHNICAL FIELD

[0001] The application belongs to the field of photocatalytic materials, and particularly relates to a rare earth Eu-doped In2O3 / In2S3 heterojunction photocatalytic material, a preparation method and application. BACKGROUND

[0002] Urea is a chemical product with a wide range of applications. Currently, industrial production mainly relies on the reaction of ammonia (NH3) and carbon dioxide (CO2) under high temperature (150-200℃) and high pressure (150-250 bar) conditions. The industrial synthesis of ammonia (NH3) also relies on the Haber-Bosch process under high temperature (350-550℃) and high pressure (150-250 bar) conditions. This results in huge energy consumption and environmental pollution in the industrial synthesis of urea. Therefore, it is necessary to develop an environmentally friendly urea production technology under mild conditions to achieve sustainable development.

[0003] The sustainability and environmental friendliness of photocatalysis provide a promising direction for urea synthesis. Currently, photocatalytic urea synthesis is mainly through the co-reduction reaction of N2 and CO2. However, this method faces many challenges. First, N2 and CO2 have very high chemical inertness, and the energy required to break the N≡N bond (940.95kJ / mol) and the C=O bond (750kJ / mol) is very high. Second, N2 and CO2 are co-reduced, and there is competition between the two, resulting in reduced utilization of photo-generated carriers and coupling product synthesis efficiency. SUMMARY

[0004] In view of the above situation, the main purpose of the present application is to provide a rare earth Eu-doped In2O3 / In2S3 heterojunction photocatalytic material, a preparation method and application to solve the above technical problems.

[0005] The present application provides a rare earth Eu-doped In2O3 / In2S3 heterojunction photocatalytic material, wherein the matrix of the In2O3 / In2S3 heterojunction photocatalytic material is In2O3 / In2S3.

[0006] The MIL-68(In) precursor is synthesized by a hydrothermal method to obtain an In2O3 hollow microporous photocatalyst;

[0007] In2S3 nanosheets are grown on the In2O3 hollow microporous photocatalyst by an oil bath method to obtain an In2O3 / In2S3 heterojunction photocatalyst;

[0008] A rare earth element Eu is doped in the matrix lattice of the In2O3 / In2S3 heterojunction photocatalyst to obtain a heterojunction photocatalytic material;

[0009] The rare earth element Eu is dispersed in the form of a single atom, and the mass fraction of the rare earth element Eu is 0.22%.

[0010] The application provides a preparation method of a rare earth Eu-doped In2O3 / In2S3 heterojunction photocatalytic material.

[0011] Step 1: terephthalic acid is added into dimethylformamide and stirred intensively to obtain a transparent solution;

[0012] Indium nitrate hydrate is added into the transparent solution and dispersed and dissolved through ultrasonic waves to obtain a clear transparent solution;

[0013] The clear transparent solution is transferred into a stainless steel autoclave with a polytetrafluoroethylene liner, heated, naturally cooled to room temperature after reaction, and then white precipitate is obtained; the white precipitate is washed alternately with dimethylformamide and anhydrous ethanol, the product is collected through centrifugation after the alternate washing, and then the product is transferred into a drying oven to dry overnight to obtain the MIL-68 (In) precursor;

[0014] The MIL-68 (In) precursor is placed on a ceramic boat and transferred into a muffle furnace to perform a heating reaction, and then an In2O3 hollow micrometer tube photocatalyst is obtained;

[0015] Step 2: indium trichloride tetrahydrate, thioacetamide and citric acid monohydrate are added into a round-bottom flask, deionized water is added into the round-bottom flask, a mixture is obtained, the mixture is uniformly dispersed through ultrasonic waves, and a uniformly dispersed solution is obtained;

[0016] The In2O3 hollow micrometer tube photocatalyst is added into the uniformly dispersed solution and stirred to obtain a stirring solution; the stirring solution is subjected to an oil bath reaction, naturally cooled to room temperature after the reaction, and the product is collected through centrifugation, the collected product is washed alternately with deionized water and anhydrous ethanol, and then the product is transferred into a drying oven to dry, so that an In2O3 / In2S3 heterojunction photocatalyst is obtained;

[0017] Step 3: the In2O3 / In2S3 heterojunction photocatalyst is dispersed in a mixed solution of deionized water and ethylene glycol and stirred to obtain an ethylene glycol dispersion;

[0018] Eu nitrate hexahydrate is dispersed in deionized water to obtain an Eu nitrate hexahydrate solution, the Eu nitrate hexahydrate solution is added into the ethylene glycol dispersion and stirred, the product is collected through centrifugation after deposition under the irradiation of a xenon lamp, and the collected product is washed alternately with deionized water and anhydrous ethanol, so that the In2O3 / In2S3 heterojunction photocatalytic material is obtained after drying in a drying oven overnight.

[0019] The application further provides application of the rare earth Eu-doped In2O3 / In2S3 heterojunction photocatalytic material, and the rare earth Eu-doped In2O3 / In2S3 heterojunction photocatalytic material prepared by the preparation method is applied to visible light photocatalytic nitrogen reduction and methanol oxidation to synthesize urea at normal temperature and pressure.

[0020] Beneficial effects:

[0021] The rare earth Eu-doped In2O3 / In2S3 hollow tubular heterojunction (Eu-IOIS) composite photocatalytic material constructed by the application has a large specific surface area, which is beneficial to expose more reaction active sites. The strong built-in electric field of the S-type heterojunction of In2O3 / In2S3 and the effect of the electron transport bridge of the rare earth Eu single atom together improve the separation and transfer of photo-generated charges. Therefore, the Eu-IOIS exhibits enhanced photocatalytic performance of N2 reduction and CH3OH oxidation to synthesize urea.

[0022] Additional aspects and advantages of the application will be made apparent by the following description and the specific examples of embodiment of the application. BRIEF DESCRIPTION OF DRAWINGS

[0023] Figure 1 are XRD patterns of different samples;

[0024] Figure 2 are SEM, TEM and AC-STEM images of the samples;

[0025] Figure 3 are urea yield diagrams of different samples under light source irradiation;

[0026] Figure 4 are urea yield diagrams of the samples under different conditions;

[0027] Figure 5 are ultraviolet diffuse reflection diagrams of different samples;

[0028] Figure 6 are photocurrent response diagrams of the samples;

[0029] Figure 7 are impedance diagrams of the samples;

[0030] Figure 8 are photoluminescence spectral diagrams of different samples. DETAILED DESCRIPTION

[0031] Embodiments of the present application are described below in detail with reference to the accompanying drawings, wherein like or similar elements are denoted by the same or similar reference signs throughout the drawings. The embodiments described below are exemplary only, and are not intended to limit the present application.

[0032] These and other aspects of embodiments of the present application will become clear from the following description and the accompanying drawings. In the description and drawings, some specific embodiments of embodiments of the present application are specifically disclosed, to represent some ways in which the principles of embodiments of the present application can be implemented, but it should be understood that the scope of embodiments of the present application is not limited thereto.

[0033] Embodiment 1

[0034] A rare earth Eu-doped In2O3 / In2S3 heterojunction photocatalytic material, a substrate of the In2O3 / In2S3 heterojunction photocatalytic material is In2O3 / In2S3;

[0035] A MIL-68(In) precursor is synthesized by a hydrothermal method to obtain an In2O3 hollow microtubule photocatalyst;

[0036] In2S3 nanosheets are grown on the In2O3 hollow microtubule by an oil bath method to obtain an In2O3 / In2S3 heterojunction photocatalyst;

[0037] A rare earth element Eu is doped in the substrate crystal lattice of the In2O3 / In2S3 heterojunction photocatalyst to obtain an In2O3 / In2S3 heterojunction photocatalytic material;

[0038] The rare earth element Eu is dispersed in the form of a single atom, and the mass fraction of the rare earth element Eu is 0.22%.

[0039] Embodiment 2

[0040] The embodiment provides a preparation method of a rare earth Eu-doped In2O3 / In2S3 heterojunction photocatalytic material, which is used for preparing the above-mentioned rare earth Eu-doped In2O3 / In2S3 heterojunction photocatalytic material, and the method comprises the following steps:

[0041] Step 1: 0.170 g of terephthalic acid is taken into 57 mL of dimethylformamide and stirred intensively to obtain a transparent solution;

[0042] 0.457 g of indium nitrate hydrate is taken into the transparent solution and dispersed and dissolved by ultrasonic waves to obtain a clear transparent solution;

[0043] The clear and transparent solution was transferred into a 100 mL polytetrafluoroethylene-lined stainless steel autoclave, and was subjected to temperature elevation heating at 95 °C for 3.6 h. After the reaction was completed, the solution was naturally cooled to room temperature to obtain a white precipitate. The white precipitate was washed with dimethylformamide and anhydrous ethanol alternately for 3 times. After the alternating washing, the product was collected by centrifugation and was transferred into an oven for drying at 76 °C overnight to obtain the MIL-68(In) precursor, which was denoted as A1.

[0044] The MIL-68(In) precursor in A1 was placed on a ceramic boat and was transferred into a muffle furnace for reaction at a temperature elevation rate of 4.5 °C / min to 445 °C for 3.6 h to obtain a light yellow In2O3 hollow micrometer tube photocatalyst, which was denoted as B1.

[0045] In step 2, 0.278 g of indium trichloride tetrahydrate, 0.333 g of thioacetamide and 0.931 g of citric acid monohydrate were added into a round-bottom flask, and 66.5 mL of deionized water was added into the round-bottom flask to obtain a mixture. The mixture was subjected to ultrasonic dispersion to obtain a uniformly dispersed solution.

[0046] In step 3, 0.095 g of the In2O3 / In2S3 heterojunction photocatalyst in C1 was dispersed in a mixed solution of 23.75 mL of deionized water and ethylene glycol, and was subjected to stirring to obtain an ethylene glycol dispersion liquid.

[0047] In step 3, 0.095 g of the In2O3 / In2S3 heterojunction photocatalyst in C1 was dispersed in a mixed solution of 23.75 mL of deionized water and ethylene glycol, and was subjected to stirring to obtain an ethylene glycol dispersion liquid.

[0048] In step 3, 0.095 g of the In2O3 / In2S3 heterojunction photocatalyst in C1 was dispersed in a mixed solution of 23.75 mL of deionized water and ethylene glycol, and was subjected to stirring to obtain an ethylene glycol dispersion liquid.

[0049] Example 3

[0050] The embodiment provides a preparation method of a rare earth Eu-doped In2O3 / In2S3 heterojunction photocatalytic material.

[0051] Step 1, 0.179g of terephthalic acid is added into 60mL of dimethylformamide and stirred intensively to obtain a transparent solution;

[0052] 0.481g of indium nitrate hydrate is taken into the transparent solution and dispersed and dissolved through ultrasonic waves to obtain a clear transparent solution;

[0053] The clear transparent solution is transferred into a 100mL polytetrafluoroethylene-lined stainless steel autoclave, 100℃ heating is carried out for 4h, after the reaction is completed, natural cooling is carried out to room temperature, a white precipitate is obtained, the white precipitate is washed with dimethylformamide and anhydrous ethanol alternately for 3 times, after the alternative washing, the product is collected through centrifugation, after the collection, the product is transferred into an oven and dried at 80℃ overnight to obtain a MIL-68(In) precursor, which is recorded as A2;

[0054] The MIL-68(In) precursor in A2 is placed on a ceramic boat and transferred into a muffle furnace, heating is carried out at a heating rate of 5℃ / min to 450℃ for 4h to obtain a light yellow In2O3 hollow micrometer tube photocatalyst, which is recorded as B2;

[0055] Step 2, 0.293g of indium trichloride tetrahydrate, 0.35g of thioacetamide and 0.979g of citric acid monohydrate are taken into a round-bottom flask, 70mL of deionized water is added into the round-bottom flask to obtain a mixture, the mixture is uniformly dispersed through ultrasonic waves to obtain a uniformly dispersed solution;

[0056] 50mg of the light yellow In2O3 hollow micrometer tube photocatalyst in B2 is added into the uniformly dispersed solution and stirred to obtain a stirring solution, the stirring solution is subjected to an oil bath reaction at 80℃ for 2h, after the reaction is completed, natural cooling is carried out to room temperature, the product is collected through centrifugation, the collected product is washed with deionized water and anhydrous ethanol alternately for 3 times, after the washing is completed, the product is transferred into an 80℃ oven and dried for 12h to obtain a yellow In2O3 / In2S3 heterojunction photocatalyst, which is recorded as C2;

[0057] Step 3, 0.1g of the In2O3 / In2S3 heterojunction photocatalyst in C2 is dispersed in 25mL of a deionized water and ethylene glycol mixed solution and stirred to obtain an ethylene glycol dispersion;

[0058] Take 0.05 g of europium nitrate hexahydrate and disperse it in 2.5 mL of deionized water to obtain a europium nitrate hexahydrate solution, add the europium nitrate hexahydrate solution to the ethylene glycol dispersion, and stir in the dark for 20 min, then deposit under the illumination of a 300 W xenon lamp with a wavelength ≥ 420 nm for 60 min, centrifuge the product after deposition, and wash it with deionized water and anhydrous ethanol alternately for 3 times, then transfer it to a drying oven at 60℃ and dry overnight to obtain a yellow In2O3 / In2S3 heterojunction photocatalytic material, denoted as D2.

[0059] Example 4

[0060] The example provides a preparation method of a rare earth Eu-doped In2O3 / In2S3 heterojunction photocatalytic material, which is used to prepare the above-mentioned rare earth Eu-doped In2O3 / In2S3 heterojunction photocatalytic material, and the method comprises the following steps:

[0061] Step 1, take 0.188 g of terephthalic acid and add it to 63 mL of dimethylformamide for vigorous stirring to obtain a transparent solution;

[0062] Take 0.505 g of indium nitrate hydrate and add it to the transparent solution for dispersion and dissolution by ultrasonic wave to obtain a clear transparent solution;

[0063] Transfer the clear transparent solution to a 100 mL polytetrafluoroethylene-lined stainless steel autoclave, heat it at 105℃ for 4.4 h, and then naturally cool it to room temperature after the reaction is completed to obtain a white precipitate, wash the white precipitate with dimethylformamide and anhydrous ethanol alternately for 3 times, centrifuge the product after the alternative washing, and then transfer it to an oven for drying at 84℃ overnight to obtain a MIL-68(In) precursor, denoted as A3;

[0064] Take the MIL-68(In) precursor in A3, place it on a ceramic boat, and transfer it to a muffle furnace for heating at a heating rate of 5.5℃ / min to 455℃ for 4.4 h to obtain a light yellow In2O3 hollow microporous tube photocatalyst, denoted as B3;

[0065] Step 2, take 0.308 g of indium trichloride tetrahydrate, 0.367 g of thioacetamide, and 1.0227 g of citric acid monohydrate and add them to a round-bottom flask, add 73.5 mL of deionized water to the round-bottom flask to obtain a mixture, and use ultrasonic wave to uniformly disperse the mixture to obtain a uniformly dispersed solution;

[0066] A 52.5 mg light yellow In2O3 hollow micrometer tube photocatalyst in B3 was added to the uniformly dispersed solution and stirred to obtain a stirring solution, and the stirring solution was subjected to an oil bath reaction at 84°C for 2.2 h. After the reaction was completed, it was naturally cooled to room temperature, and the product was collected by centrifugation. The collected product was washed with deionized water and anhydrous ethanol alternately for 3 times, and after the washing was completed, it was transferred to a 84°C oven for drying for 13.2 h to obtain a yellow In2O3 / In2S3 heterojunction photocatalyst, which was recorded as C3.

[0067] Step 3, 0.105 g of the In2O3 / In2S3 heterojunction photocatalyst in C3 was dispersed in 26.25 mL of a mixed solution of deionized water and ethylene glycol to obtain an ethylene glycol dispersion liquid;

[0068] 0.0525 g of europium nitrate hexahydrate was dispersed in 2.625 mL of deionized water to obtain a europium nitrate hexahydrate solution, which was added to the ethylene glycol dispersion liquid and stirred in the dark for 22 min. After stirring, it was subjected to deposition under the irradiation of a 300 W xenon lamp with a wavelength ≥420 nm for 66 min. After deposition, the product was collected by centrifugation and washed with deionized water and anhydrous ethanol alternately for 3 times. After the alternating washing, it was transferred to a drying oven at 63°C for drying overnight to obtain a yellow In2O3 / In2S3 heterojunction photocatalytic material, which was recorded as D3.

[0069] Application Example 1

[0070] An application of a rare earth Eu-doped In2O3 / In2S3 heterojunction photocatalytic material, the rare earth Eu-doped In2O3 / In2S3 heterojunction photocatalytic material prepared by the above-mentioned preparation method of a rare earth Eu-doped In2O3 / In2S3 heterojunction photocatalytic material is applied to visible light photocatalytic nitrogen reduction coupling methanol oxidation to synthesize urea at normal temperature and pressure;

[0071] The synthesis of urea adopts a diacetyl monoxime method to determine the generation amount of urea;

[0072] The diacetyl monoxime method specifically includes the following steps:

[0073] Step 1, 50 mL of concentrated phosphoric acid was mixed with 150 mL of concentrated sulfuric acid and distilled water to obtain a mixed solution. 50 mg of ferric trichloride was dissolved in the mixed solution and diluted to 500 mL to obtain an acidic iron solution, which was recorded as E1;

[0074] Step 2, 2.5 g of diacetyl monoxime and 50 mg of thiosemicarbazide were dissolved in distilled water and diluted to 500 mL to obtain a diacetyl monoxime thiosemicarbazide solution, which was recorded as F1;

[0075] Step 3, take 2 mL of acidic iron solution in E1 and 1 mL of diacetyl monoxime sulfenamide solution in F1 to ultrasonic mixing for 2 min, after ultrasonic mixing, add 1 mL of urea solution sample and use ultrasonic vigorous mixing for 2 min, to obtain urea mixed solution, transfer the urea mixed solution to a boiling water bath for 20 min, after the reaction is completed, naturally cool to room temperature, then use ultraviolet-visible spectrophotometer to obtain absorbance at 525 nm, and obtain the determination results according to the absorbance.

[0076] Wherein, the urea solution sample is used to obtain a calibration curve with a standard urea solution to calibrate the yield.

[0077] In order to verify the effectiveness of the present application, from Figure 1 It can be seen from that the XRD patterns of In2O3 and In2S3 can well correspond to the standard In2O3 (JCPDS PDF #06-0416) and In2S3 (JCPDS PDF #05-0731). Among them, the characteristic diffraction peaks of In2O3 are at 2θ = 30.58°, 35.47°, 51.04° and 60.68°, which are respectively attributed to its (222), (400), (440) and (622) crystal faces; while the characteristic diffraction peaks of In2S3 at 2θ = 28.80°, 33.45° and 48.00° are respectively attributed to its (111), (200) and (220) crystal faces. In addition, the characteristic diffraction peaks corresponding to In2O3 and In2S3 can be found in the XRD pattern of the heterojunction material IOIS, indicating that In2S3 has been successfully grown on In2O3. After further doping of rare earth Eu element, the XRD pattern of Eu-IOIS does not change significantly, and no diffraction peak corresponding to Eu metal clusters or Eu oxide appears, which means that the doped Eu is highly dispersed.

[0078] It can be seen from Figure 2 that In2O3 obtained by calcining MIL-68(In) retains a hollow tubular structure (a in Figure 2 , and In2S3 is in the form of irregular nanosheets stacked to form micron-sized flower balls (b in Figure 2 . In addition, from the SEM (c in Figure 2 of Eu-IOIS, it can be seen that the originally smooth hollow tubular In2O3 surface becomes rough, indicating that In2S3 nanosheets have been successfully grown. The TEM (d in Figure 2 of Eu-IOIS can also prove the hollow tubular structure, which will be beneficial to the contact adsorption and activation of the catalyst and the reactants. And from the HR-TEM image (e in Figure 2e) It was found that the lattice fringe spacing of 0.253 nm and 0.268 nm in Eu-IOIS corresponded to the (400) plane of In2O3 and the (200) plane of In2S3, respectively.

[0079] In addition, in the selected area electron diffraction (SAED) pattern of Eu-IOIS (Figure 1 1), Figure 2 f) Diffraction rings corresponding to the (004) and (225) planes of In2O3 and the (002) and (023) planes of In2S3 can also be observed in Figure 1 1. Figure 2 g) As shown in Figure 1 1, Figure 2 h) The intensity distribution of the selected area in Figure 1 1 shows that the intensity of a single Eu atom is significantly higher than that of the surrounding atoms. Figure 2 i) The corresponding elemental mapping images in Figure 1 1 show that the elements Eu, In, O, and S are uniformly distributed in Eu-IOIS.

[0080] As shown in Figure 1 1, Figure 3 and Figure 4 As shown in Figure 1 1, Figure 3 a) The urea production of In2O3 and In2S3 is very low, and the construction of heterojunction (IOIS) can significantly improve its activity, and after Eu doping, the production of photocatalytic N2 and CH3OH coupling to synthesize urea is further improved. Figure 3 The average production of urea is shown, and the production rates of In2O3, In2S3, IOIS, and Eu-IOIS are 1.14, 1.81, 15.17, and 37.04 μmol / g / h, respectively (Figure 1 1, Figure 3 b). In addition, the effects of reaction conditions on the photocatalytic coupling reaction were investigated. From Figure 4 it can be seen that: in the absence of N2 or CH3OH, no urea is generated, indicating that the product is derived from the coupling of photocatalytic N2 and CH3OH. In addition, in the absence of catalyst or in the dark, no urea is generated.

[0081] Figure 5 The UV-vis-DRS spectrum of the sample is shown in Figure 1 1, which shows that the synthesized photocatalysts exhibit certain light absorption in the ultraviolet-visible light region. Among them, In2S3 has the best light absorption characteristics, with a light absorption range of up to 600 nm and a relative light absorption intensity of 1.6. In2O3 has the worst light absorption characteristics, with a light absorption range of only 400 nm and a relative light absorption intensity of 1.2. The light absorption characteristics of IOIS and Eu-IOIS are between those of In2O3 and In2S3, and the difference is not large, indicating that the doping of Eu does not affect the light absorption performance of the sample.

[0082] Figure 6 and Figure 7 The photocurrent response and impedance plots of the prepared catalysts, the photocurrent density-time curves indicate the generation of photo-generated charges of semiconductor photocatalysts, and the smaller photocurrent density indicates that the photo-generated electrons and holes have a greater probability of recombination. As shown in Figure 6 , Eu-IOIS has a significantly high photocurrent response intensity (photocurrent density in the range of 50-120 μA·cm -1 , and the photocurrent density of other samples is less than 50 μA·cm -1 , which means that Eu-IOIS has the fastest carrier transfer speed and the highest carrier separation efficiency. The electrochemical impedance spectroscopy further studies the charge transfer efficiency of the prepared samples, and the curvature radius of the curve in the electrochemical impedance spectroscopy can directly reflect the size of the resistance of the charge transfer. As shown in Figure 7 , the curvature radius of Eu-IOIS is the smallest, indicating that the resistance of the photo-generated charges in the transfer process is the smallest, and the charge separation efficiency is the highest, which is consistent with the results of the photocurrent test.

[0083] Figure 8 The PL spectra of the samples are shown in the figure. The recombination of photo-generated electrons and holes will release energy in the form of light and heat, resulting in fluorescence phenomenon, so for photocatalysis, good catalytic effect corresponds to high separation efficiency of photo-generated charges, that is, low photoluminescence intensity. As can be seen from the figure, all samples are excited by light with a wavelength of 550 nm, and show emission signals near 830 nm. It can be observed that the photoluminescence intensity of IOIS is lower than that of In2O3 and In2S3, which means that the construction of heterojunction reduces the recombination of photo-generated electrons and holes. In addition, the peak intensity of Eu-IOIS is the lowest, indicating that the recombination rate of photo-generated carriers in Eu-IOIS is the lowest.

[0084] In the description of the present specification, the description of the terms "one embodiment", "some embodiments", "example", "specific example", or "some examples" and the like means that the specific features, structures, materials or characteristics described in connection with the embodiment or example are included in at least one embodiment or example of the present application. In the present specification, the illustrative description of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any one or more embodiments or examples in a suitable manner.

[0085] The above embodiments only express several implementation manners of the present application, and the description is more specific and detailed, but it should not be understood as a limitation on the patent scope of the present application. It should be noted that for ordinary skilled persons in the art, without departing from the concept of the present application, several modifications and improvements can be made, which are all within the protection scope of the present application. Therefore, the protection scope of the patent of the present application should be subject to the appended claims.

Claims

1. Application of a rare earth Eu-doped In2O3 / In2S3 heterojunction photocatalytic material, characterized in that, The substrate of the In2O3 / In2S3 heterojunction photocatalytic material is In2O3 / In2S3; The MIL-68-In precursor is synthesized by a hydrothermal method to obtain the In2O3 hollow microporous photocatalyst; The In2S3 nanosheet is grown on the In2O3 hollow microporous tube by an oil bath method to obtain the In2O3 / In2S3 heterojunction photocatalyst; The rare earth element Eu is doped in the substrate lattice of the In2O3 / In2S3 heterojunction photocatalyst to obtain the In2O3 / In2S3 heterojunction photocatalytic material; The In2O3 is a hollow microporous structure, the In2S3 is a nanosheet structure, the rare earth element Eu is dispersed in the form of a single atom, and the mass fraction of the rare earth element Eu is 0.22%; The In2O3 / In2S3 heterojunction photocatalytic material is used for visible light photocatalytic nitrogen reduction and coupling methanol oxidation to synthesize urea, and the urea yield is 37.04 μmol / g / h. 2.The application of the rare earth Eu-doped In 2O 3 / In 2S 3 heterojunction photocatalytic material according to claim 1, characterized in that, The preparation method of the rare earth Eu doped In2O3 / In2S3 heterojunction photocatalytic material includes the following steps: Step 1, terephthalic acid is added to dimethylformamide and stirred vigorously to obtain a transparent solution; Indium nitrate hydrate is added to the transparent solution and dispersed and dissolved by ultrasonic waves to obtain a clear transparent solution; The clear transparent solution is transferred to a stainless steel autoclave lined with polytetrafluoroethylene, heated, naturally cooled to room temperature after the reaction is completed, and a white precipitate is obtained; the white precipitate is washed alternately with dimethylformamide and anhydrous ethanol, the product is collected after alternating washing and centrifugation, and the collected product is transferred to an oven for drying overnight to obtain a MIL-68-In precursor; The MIL-68-In precursor is placed on a ceramic boat and transferred to a muffle furnace for temperature rising reaction to obtain an In2O3 hollow microporous photocatalyst; Step 2, indium trichloride tetrahydrate, thioacetamide and citric acid monohydrate are added to a round-bottom flask, deionized water is added to the round-bottom flask, a mixture is obtained, the mixture is uniformly dispersed using ultrasonic waves to obtain a uniformly dispersed solution; The In2O3 hollow microporous tube photocatalyst is added to the uniformly dispersed solution and stirred to obtain a stirring solution; the stirring solution is subjected to oil bath reaction, and after the reaction is completed, it is naturally cooled to room temperature, and the product is collected by centrifugation, and the collected product is washed with deionized water and anhydrous ethanol alternately, and after the washing is completed, it is transferred to an oven for drying to obtain an In2O3 / In2S3 heterojunction photocatalyst; the mass of the added indium trichloride tetrahydrate is 0.278-0.308 g, the mass of the thioacetamide is 0.333-0.367 g, the mass of the citric acid monohydrate is 0.931-1.027 g, the volume of the added deionized water is 66.5-73.5 mL, the mass of the added In2O3 hollow microporous tube photocatalyst is 47.5-52.5 mg, the oil bath reaction temperature is 76-84 °C, the oil bath reaction time is 1.8-2.2 h, the number of times of alternating washing with deionized water and anhydrous ethanol is 3, and the temperature of transferring to the oven for drying is 76-84 °C, and the time of transferring to the oven for drying is 10.8-13.2 h; Step 3, the In2O3 / In2S3 heterojunction photocatalyst is dispersed in a deionized water and ethylene glycol mixed solution and stirred to obtain an ethylene glycol dispersion liquid; The europium nitrate hexahydrate is dispersed in deionized water to obtain a europium nitrate hexahydrate solution, the europium nitrate hexahydrate solution is added to the ethylene glycol dispersion liquid and stirred, and then deposited under xenon lamp light, and after deposition, the product is collected by centrifugation and washed with deionized water and anhydrous ethanol alternately, and after alternating washing, it is transferred to a drying oven for drying overnight to obtain an In2O3 / In2S3 heterojunction photocatalytic material; the mass of the added In2O3 / In2S3 heterojunction photocatalyst is 0.095-0.105 g, the volume of the deionized water and ethylene glycol mixed solution is 23.75-26.25 mL, the mass of the europium nitrate hexahydrate is 0.0475-0.0525 g, the volume of the europium nitrate hexahydrate dispersed in deionized water is 2.375-2.625 mL, the stirring condition of the europium nitrate hexahydrate solution added to the ethylene glycol dispersion liquid is darkness, the stirring time is 18-22 min, the xenon lamp power is 300 W, the xenon lamp wavelength is ≥420 nm, the light deposition time is 54-66 min, the number of times of alternating washing with deionized water and anhydrous ethanol is 3, and the temperature of transferring to the drying oven for drying overnight is 57-63 °C. 3.The application of the rare earth Eu-doped In 2O 3 / In 2S 3 heterojunction photocatalytic material according to claim 2, characterized in that, In the step 1, in the process of obtaining the In2O3 hollow microtubular photocatalyst, the terephthalic acid has a mass of 0.170-0.188 g, the dimethylformamide has a volume of 57-63 mL, the indium nitrate hydrate has a mass of 0.457-0.505 g, the polytetrafluoroethylene liner has a volume of 100 mL, the stainless steel autoclave has a temperature of 95-105 ℃, the heating time is 3.6-4.4 h, the dimethylformamide and anhydrous ethanol are alternately washed for 3 times, the collection is transferred to the oven for drying overnight at a temperature of 76-84 ℃, the muffle furnace has a heating rate of 4.5-5.5 ℃ / min, the muffle furnace has a reaction temperature of 445-455 ℃, and the reaction treatment time is 3.6-4.4 h. 4.The application of the rare earth Eu-doped In 2O 3 / In 2S 3 heterojunction photocatalytic material according to claim 2, characterized in that, The obtained In2O3 hollow microtubular photocatalyst is light yellow. 5.The application of the rare earth Eu-doped In 2O 3 / In 2S 3 heterojunction photocatalytic material according to claim 2, characterized in that, The obtained In2O3 / In2S3 heterojunction photocatalyst is yellow. 6.The application of the rare earth Eu-doped In 2O 3 / In 2S 3 heterojunction photocatalytic material according to claim 2, characterized in that, The obtained In2O3 / In2S3 heterojunction photocatalytic material is yellow.

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