A method for obtaining a multichannel modified grading catalytic material by in-situ decomposition technique
By forming sulfur vacancy defect energy levels and heterojunctions in ZnIn2S4 through in-situ decomposition technology, the problems of high photogenerated carrier recombination rate and slow surface charge reaction kinetics in ZnIn2S4 photocatalytic materials were solved, achieving high efficiency and stability in photocatalysis and simplifying the preparation process.
Patent Information
- Application Number
- CN202311700355.7
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- Filing Date
- 2023-12-12
- Publication Date
- 2025-12-05
- Estimated Expiration
- 2043-12-12
AI Technical Summary
Existing ZnIn2S4 photocatalytic materials suffer from problems such as high photogenerated carrier recombination rate, low quantum efficiency, and slow surface charge reaction kinetics. Furthermore, multi-channel modification methods are subject to problems such as long processing cycles, high costs, and easy delamination of composite materials.
In-situ decomposition technology is employed to form soluble low-valence Mo ions under weakly reducing conditions through the in-situ decomposition of metal molybdates, which are then used to in-situ dope ZnIn2S4. This process creates sulfur vacancy defect levels and a MoS2/ZnIn2S4 Schottky heterojunction. Combined with soluble transition metal ions and sulfur ions, an MS/ZnIn2S4 heterojunction is formed, achieving multi-channel synergy and improving the separation and directional migration of photogenerated carriers.
This method improves the photocatalytic activity and stability of ZnIn2S4, simplifies the preparation process, reduces costs, avoids the delamination phenomenon of composite materials, and achieves highly efficient photocatalytic performance.
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Abstract
Description
TECHNICAL FIELD
[0001] The application relates to the field of nanomaterial preparation and photochemical application, and particularly relates to a preparation method for obtaining a multi-channel modified grading catalytic material by in-situ decomposition technology. BACKGROUND
[0002] Catalytic technology is an ideal new energy development method, and is also an effective way to achieve the "carbon neutralization" goal and solve the current greenhouse effect and environmental pollution. It is widely used in the fields of organic pollutant degradation, heavy metal ion removal, hydrogen and oxygen production by water photolysis, carbon dioxide photoreduction, photochemical nitrogen fixation and the like. However, the traditional photocatalytic system has problems such as low light energy utilization rate, unsatisfactory light-generated carrier separation / transfer effect and low catalytic efficiency, which limits its practical application.
[0003] Hexagonal ZnIn2S4 is a new ternary semiconductor sulfide, which has a special layered structure, a moderate band gap width, good visible light absorption and unique photoelectron performance, and is expected to be practically applied in the future. However, ZnIn2S4 still has problems to be solved, such as high light-generated carrier recombination rate, low quantum efficiency and slow surface charge reaction kinetics. Subsequently, many modification technologies have been developed, such as microstructure adjustment, heteroatom doping, cocatalyst loading and heterojunction construction. However, up to now, each modification method has its advantages and disadvantages. For example, heteroatom doping inevitably changes the ZnIn2S4 crystal structure and forms light-generated carrier recombination centers while improving the light spectrum absorption and light-generated carrier separation efficiency, resulting in the reduction of photocatalytic activity; cocatalyst loading reduces the hydrogen evolution active site and light absorption capacity while improving the surface hydrogen evolution reaction kinetics; heterojunction inevitably increases the heterojunction interface and the interface recombination of light-generated carriers while improving the light-generated carrier separation efficiency.
[0004] Recently, multi-channel modification is considered to be an effective method for improving the photocatalytic performance of ZnIn2S4, that is, by synthesizing a multi-channel modified ZnIn2S4 grading photocatalytic system, the synergistic effect of multiple components and the advantages of various modification methods are utilized, so as to realize the directional migration of photo-generated electrons and photo-generated holes, effectively inhibit the carrier recombination, accelerate the surface reaction kinetics, and finally improve the photocatalytic hydrogen evolution performance. However, the current multi-channel modification has a multi-step process, resulting in a long processing period, a complex control procedure and a high cost, and any improper processing in the steps will have an adverse effect on the photocatalytic performance; in addition, the surface of the sulfide is inert and is not easy to dissolve in water, and the layered material is easily caused during the processing under chemical conditions.
[0005] Document 1 (S. Zhang, etc. ACS Nano, 2018, 12, 751) first prepared ZnIn2S4 nanomaterial by a solvothermal method, and then prepared Lix ZnIn2S4 precursor, followed by ultrasonic separation under ice bath conditions to obtain ZnIn2S4 monolayer nanosheet with sulfur vacancy (Vs-M-ZnIn2S4), and finally MoS2 quantum dot loaded Vs-M-ZnIn2S4 system was prepared under ultrasonic-assisted solvothermal conditions. The band structure, spectral absorption and carrier separation efficiency were regulated by sulfur vacancy, and the surface photogenerated carrier dynamics was adjusted by MoS2 cocatalysis. This synergistic effect led to high-efficiency hydrogen evolution activity. This method has high requirements for experimental conditions, and impurity phases are easily formed. The cocatalyst is severely lost during the photocatalytic reaction, which leads to rapid reduction of photocatalytic performance and stability. Moreover, this method is not suitable for mass production.
[0006] Document 2 (D. Majhi, etc. J. Mater. Chem. A., 2020, 8, 21729) first prepared tetragonal phase β-Bi2O3 material by hydrothermal method and high temperature solid phase sintering method, then added TAA for condensation reflux to obtain binary β-Bi2O3 / Bi2S3 material, and finally prepared Bi2S3 / β-Bi2O3 / ZnIn2S4 ternary heterojunction material under condensation reflux conditions. This method uses the co-assembly of Bi2S3 and ZnIn2S4 with β-Bi2O3 to modify ZnIn2S4 synergistically through double Z-type heterostructure. However, this method requires very high experimental operation, and the preparation process is complex, which greatly consumes raw materials and is not suitable for mass production.
[0007] Document 3 (Y. Peng, etc. J. Energy Chem., 2022, 75, 276) designed a MoS2 modified oxygen-doped ZnIn2S4 nanosheet, i.e. first prepared MoS2 nanomaterial by solvothermal method, then assembled MoS2 on the surface of oxygen-doped ZnIn2S4 nanosheet by PVP-assisted solvent method, to prepare MoS2 / O-ZnIn2S4 hierarchical catalytic material, and synergistically modified the photocatalytic activity of ZnIn2S4 by oxygen doping and MoS2 cocatalysis. This preparation process is prone to cause the product to be easily layered due to the strong inertness of MoS2 surface, and it is not easy to obtain a uniformly distributed and loaded composite system. The morphology and structure are not easy to control, and the introduction of PVP high molecular material leads to changes in semiconductor properties, and the catalytic activity is limited.
[0008] Document 4 (L. Wang, etc. Chin. J. Catal., 2022, 43, 2720) first prepared g-C3N4 nanomaterials by high-temperature solid-phase method, then obtained Ti3C2 MXene nanodispersion by HF acid etching assisted ultrasonic stripping method, and finally added Ti3C2 MXene dispersion, g-C3N4 dispersion, zinc source, indium source and sulfur source in turn to obtain ZnIn2S4 / g-C3N4 / Ti3C2 MXene hybrid under oil bath conditions. The high-efficiency multi-channel modified catalytic system is obtained by Z-type ZnIn2S4 / g-C3N4 heterojunction and Ti3C2 assisted catalysis modification. This method has high energy consumption, is not environmentally friendly, has complex process, difficult process control, and is easy to form impurity phase; due to the strong inertness of g-C3N4 surface, it is not easy to build a perfect heterojunction interface.
[0009] Document 5 (J. Liao, etc. J. Alloy. Compd., 2023, 938, 168501) prepared black phosphorus BP crystals by chemical vapor transport method, then grew ZnIn2S4 nanosheets on black phosphorus nanosheet (BPNSs) by solvothermal method, and finally deposited Au nanoparticles on the surface of BPNSs / ZIS by photoreduction method, thereby obtaining ternary Au / BPNSs / ZnIn2S4 heterojunction. The catalytic system is modified by II-type BPNSs / ZnIn2S4 heterojunction and noble metal Au assisted catalysis. The preparation process of this method is complex, the system construction is difficult, the black scale safety control requirement is high, and the complex preparation process and the addition of noble metal greatly increase the cost. SUMMARY
[0010] In view of the shortcomings of the prior art, the present application develops a method for obtaining a multi-channel modified hierarchical catalytic material by in-situ decomposition technology. The present application uses a simple in-situ structure trimming technology to obtain a multi-channel modified hierarchical catalytic material, that is, by in-situ decomposition of metal molybdate, Mo ions are converted from +6 valence state to +5 valence state, +4 valence state and other low valence state Mo ions under weak reduction conditions, so that a part of soluble low valence Mo ions or soluble transition metal ions are in-situ doped with ZnIn2S4 to form sulfur vacancy defect levels, thereby reducing the ZnIn2S4 conduction band potential, improving the utilization rate of solar spectrum and the separation efficiency of photo-generated carriers; another part of the soluble Mo 4+ ions combine with S 2- ions to form MoS2 / ZnIn2S4 Schottky heterojunction to realize directional migration of photo-generated carriers; moreover, the soluble transition metal ions formed by in-situ decomposition can also form MS / ZnIn2S4 heterojunction with sulfur ions to further improve the separation efficiency of photo-generated carriers; that is, by the multi-channel synergistic effect of metal ion doping, sulfur vacancy, assisted catalysis and heterojunction, the photocatalytic activity of ZnIn2S4 is finally improved.
[0011] The present application is based on multi-component and multi-channel synergistic effect, fully utilizes the advantages of various modification methods, so as to achieve efficient separation and directional migration of photo-generated electrons or holes, effectively inhibit the recombination of photo-generated carriers, realize high efficiency operation of multi-component catalytic system, and improve the light stability.
[0012] To achieve the above object, the technical scheme adopted by the present application is:
[0013] A method for obtaining multi-channel modified graded catalytic material by in-situ decomposition technology, first, a transition metal molybdate nanomaterial is prepared by hydrothermal method, then the transition metal molybdate nanomaterial prepared by hydrothermal method is added into an aqueous solvent, and ultrasonic treatment is performed to uniformly disperse the transition metal molybdate nanomaterial in the aqueous solvent, then zinc source, indium source and sulfur source are sequentially added into the ultrasonic treated aqueous solvent and fully stirred, after completion of stirring, water bath reaction is performed, by in-situ decomposition of the metal molybdate, the transition from +6 valence state to low valence state molybdenum ions of +5 valence state and +4 valence state is realized under weak reduction conditions, so that part of the soluble low valence state molybdenum ions or soluble transition metal ions in-situ dope ZnIn2S4 to form sulfur vacancy defect levels, thereby reducing the ZnIn2S4 conduction band potential, improving the utilization rate of solar spectrum and the separation efficiency of photo-generated carriers; another part of the soluble +4 valence state Mo ions and -2 valence state sulfur ions form MoS2 / ZnIn2S4 Schottky heterojunction to realize directional migration of photo-generated carriers; at the same time, the soluble transition metal ions formed by in-situ decomposition can also form MS / ZnIn2S4 heterojunction with sulfur ions to further improve the separation efficiency of photo-generated carriers; that is, ion doping, sulfur vacancy, cocatalysis and heterojunction multi-channel synergistic effect are used to improve the catalytic performance, after the reaction is completed, the product is separated, washed and dried to obtain high-efficiency and stable multi-channel modified graded catalytic material.
[0014] The specific steps are as follows:
[0015] Step 1, adding transition metal salt into deionized water and continuously stirring until all are dissolved to obtain solution A, the molar concentration of the transition metal salt in the solution A is within 0.02-0.08 mol / L;
[0016] Step 2, adding molybdenum source into deionized water and continuously stirring until all are dissolved to obtain solution B, the molar concentration of the molybdenum source in the solution B is within 0.05-0.2 mol / L;
[0017] Step 3, under the condition of continuous stirring, slowly adding solution B into solution A, and transferring the mixed solution into a reaction kettle with Teflon lining, sealing and placing in an oven for constant temperature hydrothermal reaction;
[0018] Step 4, after the hydrothermal reaction is completed, the precipitate in the reactor is centrifuged and cleaned with deionized water and anhydrous ethanol, and then the cleaned precipitate is dried in an oven to obtain the MMoO4 precursor product, wherein M is selected according to the molybdenum source, including elements: Zn, Cd, Co, Cu, Fe, Mn, Cr, Pb;
[0019] Step 5, the MMoO4 precursor product is added to deionized water, and is uniformly dispersed by ultrasonic waves to obtain a MMoO4 precursor dispersion, wherein the amount of the precursor MMoO4 is calculated based on the zinc source, the molar ratio of the molybdenum source to the zinc source is 0.005-0.20, and the volume of the deionized water is 80-120 mL;
[0020] Step 6, a soluble zinc source, a soluble indium source and a soluble sulfur source are sequentially added to the MMoO4 precursor dispersion in a molar ratio of 1:2:4, and are fully stirred until all are dissolved, and then the solution is transferred to a constant-temperature water bath for water bath reaction;
[0021] Step 7, the precipitate is separated from the product after the water bath reaction, and is cleaned with deionized water and anhydrous ethanol, and then is dried to obtain a series of multi-channel modified hierarchical catalytic materials.
[0022] Further, in step 1, the addition ratio of deionized water to transition metal salt satisfies 2-4 mmol of transition metal salt per 50-100 mL of deionized water; the transition metal salt is nitrate M(NO3)2·4H2O or acetate (CH3COO)2M, wherein M includes Zn, Cd, Co, Cu, Fe, Mn, Cr, Pb; the stirring time of solution A until all are dissolved is 0.2-1 h.
[0023] Further, in step 2, the molybdenum source is ammonium molybdate or sodium molybdate, and the addition ratio of deionized water to molybdenum source satisfies 2-4 mmol of molybdenum source in 20-40 mL of deionized water; the stirring time of solution B until all are dissolved is 0.2-1 h.
[0024] Further, in step 3, the solution B is slowly added to solution A at a speed of 30-60 drops / min, and after being added, the molar ratio of the molybdenum source to the M source is 0.5-1; the continuous stirring time of solution A after solution B is added is 0.5-1 h; the hydrothermal reaction conditions are: the hydrothermal temperature is 120-200℃, and the hydrothermal time is 10-24 h.
[0025] Further, in step 4, the precipitate is washed with deionized water for 3-4 times, and then washed with anhydrous ethanol for 1-2 times; the drying condition is that the drying temperature is 60-80℃, and the drying time is 6-12h.
[0026] Further, in step 5, the volume of deionized water is 80-120mL, and the amount of precursor MMoO4 is converted according to the molar ratio of M: zinc source of 0.005-0.20 based on the zinc source in each 80-120mL of deionized water; the ultrasonic time of the dispersion liquid is 1-2h.
[0027] Further, in step 6, the soluble zinc source includes one of zinc acetate and zinc chloride, the soluble indium source includes one of indium chloride and indium nitrate, and the soluble sulfur source includes one of thioacetamide and sodium sulfide; the concentration of the zinc source is 0.03-0.1mol / L; the stirring time is 0.2-1h; and the water bath condition is that the constant temperature water bath temperature is 70-80℃, and the constant temperature water bath time is 3-6h.
[0028] Further, in step 7, the precipitate is washed with deionized water for 3-4 times, and then washed with anhydrous ethanol for 1-2 times; the drying condition is that the drying temperature is 60-80℃, and the drying time is 6-12h.
[0029] An application of a multi-channel modified hierarchical catalytic material obtained by an in-situ decomposition technology, wherein the multi-channel modified hierarchical catalytic material is applied in the field of photochemistry, including water splitting to produce hydrogen, photocatalytic degradation, photocatalytic CO2 reduction, and photocatalytic nitrogen fixation to synthesize ammonia.
[0030] Beneficial effects: the application can successfully prepare a series of multi-channel modified hierarchical catalytic materials by reasonably selecting raw materials, adopting a simple hydrothermal / water bath two-step method, and based on a simple in-situ decomposition technology. The multi-channel modified hierarchical catalytic material has excellent photocatalytic performance and good photochemical stability. The application 1) successfully prepares multi-channel modified hierarchical catalytic materials with good performance by accurately controlling process parameters such as raw material types and amounts, hydrothermal / water bath temperature, and hydrothermal / water bath time; 2) in the water bath reaction process, based on the differences in ionic radius and electronegativity, the types of transition metal ions of molybdate are reasonably selected and the addition amount is accurately controlled, ion doping in the in-situ decomposition process is realized, and the sulfur vacancy defect level is accurately regulated, thereby effectively improving the photo-generated carrier separation efficiency and spectral absorption capacity; 3) in the water bath reaction process, by accurately screening the in-situ decomposition products of transition metal molybdate and the types of soluble ions under water bath conditions, the type and energy band structure of the second phase semiconductor are effectively controlled, thereby preparing different types of cocatalysts and heterojunction systems, achieving efficient separation of photo-generated carriers and directional migration of photo-generated charges, and realizing the excellent photochemical stability and photocatalytic activity of ZnIn2S4; 4) in the water bath reaction process, the in-situ decomposition of metal molybdate forms a soluble ionic liquid, thereby ensuring the chemical reaction in the ionic state, which is conducive to the formation of a perfect heterojunction interface, and thus the composite material is not prone to delamination.
[0031] Compared with the prior art, the application has the following advantages due to the adoption of the above scheme:
[0032] 1) In the preparation process of the composite material, the application mainly based on in-situ decomposition technology, adopts a simple hydrothermal / water bath method, and can prepare multi-channel modified hierarchical catalytic materials through simple steps, which greatly simplifies the steps and process of the preparation process, improves the preparation efficiency, and reduces the preparation cost, compared with the need for sequential preparation through multiple steps in the previous photocatalytic technology.
[0033] 2) The application utilizes the in-situ decomposition reaction of molybdate to realize the in-situ multi-channel modification of ZnIn2S4, that is, fully utilizes the synergistic effect of heteroatomic doping, lattice defects, cocatalysis, and heterojunction, effectively improves the photo-generated carrier separation efficiency and transport dynamics of ZnIn2S4, and finally improves the photocatalytic performance of ZnIn2S4.
[0034] 3) Because the migration rate of photo-generated holes is much slower than that of photo-generated electrons, the extraction of photo-generated holes is more difficult. The method can realize the directional extraction of photo-generated holes by the synergistic effect of multiple components, and finally effectively improves the photochemical stability of ZnIn2S4.
[0035] 4) Due to the use of in-situ decomposition technology, it is ensured that all raw materials react in ionic state, the efficient compounding of the cocatalyst and the second phase heterogeneous component and ZnIn2S4 is realized, so as to obtain a perfect heterogeneous interface, and the delamination of multi-components is avoided. BRIEF DESCRIPTION OF DRAWINGS
[0036] Figure 1 XRD patterns of different samples of example 1 of the method for obtaining multi-channel modified hierarchical catalytic materials by using in-situ decomposition technology according to the application.
[0037] Figure 2 EPR patterns of different samples of example 1 of the method for obtaining multi-channel modified hierarchical catalytic materials by using in-situ decomposition technology according to the application.
[0038] Figure 3 Mo 3d XPS narrow scan patterns of different samples of example 1 of the method for obtaining multi-channel modified hierarchical catalytic materials by using in-situ decomposition technology according to the application.
[0039] Figure 4 XRD patterns of samples of example 1 of the method for obtaining multi-channel modified hierarchical catalytic materials by using in-situ decomposition technology according to the application.
[0040] Figure 5 FESEM patterns of different samples of example 1 of the method for obtaining multi-channel modified hierarchical catalytic materials by using in-situ decomposition technology according to the application.
[0041] Figure 6 HRTEM patterns of the optimal sample of example 1 of the method for obtaining multi-channel modified hierarchical catalytic materials by using in-situ decomposition technology according to the application.
[0042] Figure 7 Hydrogen evolution performance patterns of different samples of example 1 of the method for obtaining multi-channel modified hierarchical catalytic materials by using in-situ decomposition technology according to the application.
[0043] Figure 8 Hydrogen evolution mechanism patterns of example 1 of the method for obtaining multi-channel modified hierarchical catalytic materials by using in-situ decomposition technology according to the application.
[0044] Figure 9 XRD patterns of different samples of example 2 of the method for obtaining multi-channel modified hierarchical catalytic materials by using in-situ decomposition technology according to the application.
[0045] Figure 10 EPR patterns of different samples of example 2 of the method for obtaining multi-channel modified hierarchical catalytic materials by using in-situ decomposition technology according to the application.
[0046] Figure 11Mo 3d XPS narrow scan of different samples of Example 2 of the method for obtaining multi-channel modified hierarchical catalytic material by in-situ decomposition technology of the present application.
[0047] Figure 12 FTIR of different samples of Example 2 of the method for obtaining multi-channel modified hierarchical catalytic material by in-situ decomposition technology of the present application.
[0048] Figure 13 HRTEM of the optimal sample of Example 2 of the method for obtaining multi-channel modified hierarchical catalytic material by in-situ decomposition technology of the present application. DETAILED DESCRIPTION
[0049] The present application will be further described below in conjunction with specific examples.
[0050] Example 1:
[0051] First, 0.6169 g of Cd(NO3)2·6H2O was weighed and dissolved in 60 mL of deionized water, marked as solution A, and stirred at room temperature for 30 min; 0.4893 g of Na2Mo4·2H2O was weighed and dissolved in 20 mL of distilled water, marked as solution B, and stirred at room temperature for 30 min; then solution B was slowly added to solution A, stirred at room temperature for 30 min, and a uniform transparent solution was obtained; the solution was transferred to a 100 mL Teflon-lined reaction kettle, sealed and placed in an oven for hydrothermal reaction, the hydrothermal conditions were: hydrothermal temperature was 160℃, and hydrothermal time was 12 h; after the reaction was completed, the precipitate was washed with deionized water 3 times and absolute ethanol 2 times, and dried at 70℃ for 10 h to obtain CdMoO4 precursor powder.
[0052] Then, 40.9 mg of CdMoO4 precursor product was ultrasonically dispersed in 80 mL of distilled water, marked as solution A; 0.4089 g of ZnCl2 and 0.4508 g of TAA were sequentially added to solution A, and stirred at room temperature for 30 min; 0.9812 g of In(NO3)2·6H2O was weighed and dissolved in 20 mL of distilled water, marked as solution B, and stirred at room temperature for 30 min; then, solution B was slowly added to solution A under magnetic stirring, and stirred at room temperature for 30 min; the suspension was placed in a 80℃ water bath for 6 h. After the reaction was completed, the precipitate was washed with deionized water 4 times and absolute ethanol 1 time; then dried at 70℃ for 10 h to obtain multi-channel modified MoS2 / Cd-ZnIn2S4 / CdS hierarchical catalytic material.
[0053] Figure 1The XRD patterns of different samples of the embodiment 1 of the method for obtaining multi-channel modified grading catalytic materials by using an in-situ decomposition technology are shown in the figure. It can be seen from the figure that: adding a small amount of CdMoO4 has little effect on the phase of the product, but the (110) crystal face peak of the hexagonal phase ZnIn2S4 gradually migrates to a small angle, indicating that the Cd ion with a larger ion radius is doped into the ZnIn2S4 crystal lattice, and generally, metal ion doping helps to introduce an intermediate energy level, reduce the conduction band potential of ZnIn2S4, and thus improve the utilization rate of photons.
[0054] Figure 2 The EPR patterns of different samples of the embodiment 1 of the method for obtaining multi-channel modified grading catalytic materials by using an in-situ decomposition technology are shown in the figure. It can be seen from the figure that: the multi-channel modified catalytic material shows a strong signal at g = 2.003, indicating that ion doping leads to the formation of ZnIn2S4 sulfur vacancies, and generally, the formation of sulfur vacancies helps to form a defect site, reduce the migration free path of photo-generated carriers, and thus increase the separation efficiency of photo-generated carriers, ultimately improving the photocatalytic activity of ZnIn2S4.
[0055] Figure 3 The Mo 3d XPS narrow scan patterns of different samples of the embodiment 1 of the method for obtaining multi-channel modified grading catalytic materials by using an in-situ decomposition technology are shown in the figure. It can be seen from the figure that: after in-situ decomposition of CdMoO4, Mo 6+ The chemical state is obviously converted to Mo 4+ The chemical state, and a new peak at 226.3 eV corresponds to Mo-S, confirming the existence of MoS2.
[0056] Figure 4 The XRD patterns of different samples of the embodiment 1 of the method for obtaining multi-channel modified grading catalytic materials by using an in-situ decomposition technology are shown in the figure. It can be seen from the figure that: when only a sulfur source is added to the CdMoO4 dispersion liquid, CdS is generated in the final product, indicating that CdS product is generated during the in-situ decomposition of CdMoO4.
[0057] Figure 5 The FESEM patterns of different samples of the embodiment 1 of the method for obtaining multi-channel modified grading catalytic materials by using an in-situ decomposition technology are shown in the figure. Among them, Figure 5 (a) in the figure is the FESEM pattern of pure phase ZnIn2S4, Figure 5 (b) in the figure is the FESEM pattern of the optimal sample. It can be seen from the figure that: after water bath reaction, the micro-morphology of ZnIn2S4 gradually evolves from nanoflower to irregular flake structure, and the surface of ZnIn2S4 becomes rough, indicating that after in-situ decomposition of CdMoO4, the microstructure and morphology of ZnIn2S4 are obviously affected by cadmium ion doping, MoS2 complex loading and CdS hetero-component.
[0058] Figure 6 The HRTEM images of the optimal sample of Example 1 of the method for obtaining a multi-channel modified hierarchical catalytic material by using an in-situ decomposition technique of the application are shown in Figures A and B. It can be seen from the figures that the lattice fringes of 0.32 nm, 0.34 nm and 0.22 nm correspond to the (102) crystal plane of hexagonal ZnIn2S4, the (111) crystal plane of cubic CdS and the (103) crystal plane of hexagonal MoS2, respectively, further indicating that the final product is a MoS2 / Cd-ZnIn2S4 / CdS hierarchical catalytic material.
[0059] Figure 7 The hydrogen evolution performance of different samples of Example 1 of the method for obtaining a multi-channel modified hierarchical catalytic material by using an in-situ decomposition technique of the application is shown in Figure. It can be seen from the figure that under visible light irradiation, the construction of the multi-channel modified MoS2 / Cd-ZnIn2S4 / CdS catalytic material has a significant improvement in hydrogen evolution performance, and the hydrogen evolution rate of the optimal sample is 11.49 mmol·g -1 ·h -1 , which is 4.79 times that of pure-phase ZnIn2S4.
[0060] Figure 8 The hydrogen evolution mechanism of Example 1 of the method for obtaining a multi-channel modified hierarchical catalytic material by using an in-situ decomposition technique of the application is shown in Figure. It can be seen from the figure that because the MoS2 / Cd-ZnIn2S4 / CdS catalytic material integrates ion doping, a type II Cd-ZnIn2S4 / CdS heterojunction and a MoS2 / Cd-ZnIn2S4 Schottky heterojunction, directional migration of photo-generated carriers is realized, i.e. after photoexcitation, the photo-generated electrons are migrated from CdS to Cd-ZnIn2S4 under the action of an internal electric field, and are further migrated to MoS2, and are reduced to produce hydrogen on the surface of MoS2, while the photo-generated holes are migrated from Cd-ZnIn2S4 to the surface of CdS, and are consumed by a sacrificial agent on the surface of CdS.
[0061] Example 2:
[0062] Firstly, 1.112 mg of FeSO4·7H2O is dissolved in 40 mL of distilled water, marked as solution A, and stirred at room temperature for 30 min; 0.968 mg of Na2Mo4·2H2O is dissolved in 40 mL of distilled water, marked as solution B, and stirred at room temperature for 30 min; then solution B is slowly added to solution A, stirred at room temperature for 30 min, and a uniform transparent solution is obtained; the solution is transferred into a 100 mL Teflon-lined reaction kettle, sealed and placed in an oven for hydrothermal reaction, the hydrothermal temperature is 180 ℃, and the hydrothermal time is 24 h; after the reaction is completed, the precipitate is washed with deionized water for 3 times, washed with anhydrous ethanol for 2 times, and dried at 60 ℃ for 12 h to obtain a FeMoO4 precursor.
[0063] Then, 32.4 mg of the FeMoO4 precursor product is ultrasonically dispersed in 80 mL of deionized water, marked as solution A; 0.4089 g of ZnCl2 and 0.4508 g of TAA are sequentially added to solution A, and stirred at room temperature for 30 min; 0.9812 g of In(NO3)2·6H2O is dissolved in 20 mL of distilled water, marked as solution B, and stirred at room temperature for 30 min; then, solution B is slowly added to solution A under magnetic stirring, and stirred at room temperature for 30 min; the obtained suspension is placed in a 80 ℃ water bath for reaction for 6 h. After the reaction is completed, the precipitate is washed with deionized water for 4 times, washed with anhydrous ethanol for 1 time; then dried at 70 ℃ for 10 h to obtain a multi-channel modified FeS2 / Mo-ZnIn2S4 / FeOOH hierarchical catalytic material.
[0064] Figure 9 The XRD patterns of different samples of embodiment 2 of the method for obtaining a multi-channel modified hierarchical catalytic material by using an in-situ decomposition technology according to the application are shown in the figure. It can be known from the figure that a small amount of FeMoO4 has little effect on the ZnIn2S4 phase, but the (006) crystal face peak of the hexagonal ZnIn2S4 gradually migrates to a small angle, and the heteroion with a larger ionic radius is doped into the ZnIn2S4 lattice.
[0065] Figure 10 The EPR patterns of different samples of embodiment 2 of the method for obtaining a multi-channel modified hierarchical catalytic material by using an in-situ decomposition technology according to the application are shown in the figure. It can be known from the figure that the multi-channel modified catalytic material shows a strong signal at g = 2.003, indicating that the ion doping causes the formation of a ZnIn2S4 sulfur vacancy.
[0066] Figure 11 The Mo 3d XPS narrow scan patterns of different samples of embodiment 2 of the method for obtaining a multi-channel modified hierarchical catalytic material by using an in-situ decomposition technology according to the application are shown in the figure. It can be known from the figure that after the in-situ decomposition of FeMoO4, Mo 6+Chemical state conversion to Mo 5+ Chemical state.
[0067] Figure 12 The FTIR diagram of the different samples of Example 2 of the method for obtaining a multi-channel modified hierarchical catalytic material by using an in-situ decomposition technique of the present application is shown in the figure. It can be seen from the figure that the typical FeOOH characteristic peak appears at 890 cm -1 , indicating that the product contains FeOOH product.
[0068] Figure 13 The HRTEM diagram of the optimal sample of Example 2 of the method for obtaining a multi-channel modified hierarchical catalytic material by using an in-situ decomposition technique of the present application is shown in the figure. It can be seen from the figure that the lattice fringes of 0.32 nm and 0.24 nm correspond to the (102) crystal plane of hexagonal ZnIn2S4 and the (210) crystal plane of cubic FeS2, respectively, and a large number of amorphous structures exist in the transmission electron microscope, which should be caused by amorphous FeOOH, further indicating that the product is a FeS2 / Mo-ZnIn2S4 / FeOOH hierarchical catalytic material.
[0069] Example 3:
[0070] First, 0.2726 g of ZnCl2 was dissolved in 35 mL of distilled water, labeled as solution A, and stirred at room temperature for 30 min; 0.4839 g of Na2Mo4·2H2O was dissolved in 35 mL of distilled water, labeled as solution B, and stirred at room temperature for 30 min; then solution B was slowly added to solution A, which was stirred at room temperature for 30 min to obtain a uniform transparent solution; the solution was transferred into a 100 mL Teflon-lined reaction kettle, which was sealed and placed in an oven for hydrothermal reaction, with the hydrothermal temperature being 160°C and the hydrothermal time being 10 h; after the reaction was completed, the precipitate was washed with deionized water for 3 times and absolute ethanol for 2 times, and dried at 60°C for 12 h to obtain a ZnMoO4 precursor product.
[0071] Then, 33.8 mg of ZnMoO4 precursor product was ultrasonically dispersed in 80 mL of distilled water, labeled as solution A; 0.4089 g of ZnCl2 and 0.4508 g of TAA were sequentially added to solution A, which was stirred at room temperature for 30 min; 0.9812 g of In(NO3)2·6H2O was dissolved in 20 mL of distilled water, labeled as solution B, and stirred at room temperature for 30 min; then, solution B was slowly added to solution A under magnetic stirring, and stirred at room temperature for 30 min; the obtained suspension was placed in a 80°C water bath for reaction for 6 h. After the reaction was completed, the precipitate was washed with deionized water for 4 times and absolute ethanol for 1 time; then dried at 70°C for 10 h to obtain a multi-channel modified catalytic material.
[0072] The above-mentioned embodiments of the present application are only illustrative and not restrictive, and the scope of the present application is defined by the claims. Therefore, as long as the multi-channel modified grading catalytic material is prepared by the method, it is considered to fall within the protection scope of the present application without departing from the basic idea of the present application. The upper and lower limits, interval values of each raw material of the present application, and the upper and lower limits, interval values of the process parameters (time, temperature, etc.) can all achieve the present application, which are not listed one by one.
Claims
1. A method for obtaining a multi-channel modified split-rated catalytic material by in-situ decomposition technology, characterized in that: First, the transition metal molybdate nano material is prepared by a hydrothermal method, then the transition metal molybdate nano material prepared by the hydrothermal method is added into an aqueous solvent and is subjected to ultrasonic treatment to uniformly disperse the transition metal molybdate nano material in the aqueous solvent, then a zinc source, an indium source and a sulfur source are sequentially added into the aqueous solvent subjected to the ultrasonic treatment and are fully stirred, after the stirring is completed, a water bath reaction is performed, the in-situ decomposition of the metal molybdate is utilized, the transition from the +6 valence state of the molybdenum ion to the low valence state of the +5 valence state and the +4 valence state of the molybdenum ion under weak reduction conditions is realized, the in-situ doping of part of the soluble low valence state molybdenum ion or the soluble transition metal ion to ZnIn2S4 is realized, the sulfur vacancy defect level is formed, thereby reducing the conduction band potential of ZnIn2S4, improving the utilization rate of the solar spectrum and the separation efficiency of the photo-generated carriers; another part of the soluble +4 valence state Mo ion combines with the -2 valence state sulfur ion to form a MoS2 / ZnIn2S4 Schottky heterojunction, realizing the directional migration of the photo-generated carriers; meanwhile, the soluble transition metal ion formed by the in-situ decomposition can also form a sulfide / ZnIn2S4 heterojunction with the sulfur ion, further improving the separation efficiency of the photo-generated carriers; that is, the ion doping, sulfur vacancy, cocatalysis and heterojunction multi-channel synergistic effect are utilized to improve the performance, after the reaction is completed, the product is separated, washed and dried to obtain a high-efficiency and stable multi-channel modified grading catalyst material; The specific steps are as follows: Step 1, a transition metal salt is added into deionized water and continuously stirred until it is completely dissolved to obtain solution A, the molar concentration of the transition metal salt in the solution A is within 0.02-0.08 mol / L; Step 2, a molybdenum source is added into deionized water and continuously stirred until it is completely dissolved to obtain solution B, the molar concentration of the molybdenum source in the solution B is within 0.05-0.2 mol / L; Step 3, under the condition of continuous stirring, the solution B is slowly added into the solution A, and the uniformly mixed solution is transferred into a reaction kettle with a Teflon lining, sealed and placed in an oven for constant temperature hydrothermal reaction; Step 4, after the hydrothermal reaction is completed, the precipitate in the reaction kettle is centrifuged and separated, and then deionized water and anhydrous ethanol are used to wash the precipitate in sequence, and then the washed precipitate is placed in an oven for drying, finally the MMoO4 precursor product is obtained, wherein M is Zn or Cd; Step 5, the MMoO4 precursor product is added into deionized water and uniformly dispersed by ultrasonic waves to obtain an MMoO4 precursor dispersion liquid, wherein the molar ratio of M in the MMoO4 precursor to the zinc source is 0.005-0.20, and the volume of deionized water used is 80-120 mL; Step 6, a soluble zinc source, a soluble indium source and a soluble sulfur source are sequentially added into the MMoO4 precursor dispersion liquid in a proportion of 1:2:4 in terms of molar ratio, and are fully stirred until they are completely dissolved, and then the solution is transferred into a constant temperature water bath for water bath reaction; Step 7, centrifugal separation of the precipitate from the product after the end of the water bath reaction, then the precipitate is washed with deionized water and anhydrous ethanol, and then the precipitate is dried to obtain a multi-channel modified hierarchical catalytic material.
2. The method of claim 1, wherein the in-situ decomposition technique is used to obtain a multi-channel modified rating catalyst material, characterized in that: In step 1, the addition ratio of deionized water and transition metal salt meets 2-4 mmol of transition metal salt per 50-100 mL of deionized water; the transition metal salt is nitrate or acetate, and the transition metal is Zn or Cd; the stirring time to obtain solution A is 0.2-1 h.
3. The method of claim 1, wherein the in-situ decomposition technique is used to obtain a multi-channel modified rating catalyst material, characterized by: In step 2, the molybdenum source is ammonium molybdate or sodium molybdate, and the addition ratio of deionized water and molybdenum source meets 2-4 mmol of molybdenum source in 20-40 mL of deionized water, and the stirring time to obtain solution B is 0.2-1 h.
4. The method of claim 1, wherein the in-situ decomposition technique is used to obtain a multi-channel modified rating catalyst material, characterized in that: In step 3, the speed of slowly dropping solution B into solution A is 30-60 drops / min, and the molar ratio of molybdenum source to transition metal salt after dropping solution B is 0.5-1, and the continuous stirring time of solution A after dropping solution B is 0.5-1 h; the hydrothermal reaction conditions are: hydrothermal temperature is 120-200 ℃, and hydrothermal time is 10-24 h.
5. The method of claim 1, wherein the in-situ decomposition technique is used to obtain a multi-channel modified rating catalyst material, characterized in that: In step 4, the precipitate is first washed with deionized water 3-4 times, and then washed with anhydrous ethanol 1-2 times; the drying conditions are: drying temperature is 60-80 ℃, and drying time is 6-12 h.
6. The method of claim 1, wherein the in-situ decomposition technique is used to obtain a multi-channel modified rating catalyst material, characterized by: In step 5, the ultrasonic uniform dispersion time is 1-2 h.
7. The method of claim 1, wherein the in-situ decomposition technique is used to obtain a multi-channel modified fractionated catalytic material, characterized by: In step 6, the soluble zinc source includes one of zinc acetate and zinc chloride, the soluble indium source includes one of indium chloride and indium nitrate, and the soluble sulfur source includes one of thioacetamide and sodium sulfide; the zinc source concentration is 0.03-0.1 mol / L; the stirring time is 0.2-1 h; and the water bath conditions are: constant temperature water bath temperature is 70-80 ℃, and constant temperature water bath time is 3-6 h.
8. The method of claim 1, wherein the in-situ decomposition technique is used to obtain a multi-channel modified rating catalyst material, characterized by: In step 7, the precipitate is washed with deionized water 3-4 times, and then washed with anhydrous ethanol 1-2 times; the drying conditions are: drying temperature is 60-80 ℃, and drying time is 6-12 h.
9. Use of a multi-channel modified rating catalyst material obtained by the method of claim 1, characterized in that: The multi-channel modified hierarchical catalytic material is applied to the field of photochemistry, including water splitting to produce hydrogen, photocatalytic degradation, photocatalytic CO2 reduction, and photocatalytic nitrogen fixation to synthesize ammonia.