In-situ chemical tailoring methods and applications of few-layer amorphous chalcogenides

Abstract

This invention provides a general method for in-situ chemical tailoring to prepare few-layer amorphous chalcogenides, thereby obtaining piezoelectric catalysts with high piezoelectricity and abundant surface sites, belonging to the field of inorganic non-metallic materials technology. Specific preparation steps: 1) Dissolve 1-10 mmol of reagent A in 40 mL of alkaline solution to obtain solution A; 2) Dissolve 3-30 mmol of reagent B in 40 mL of citric acid solution to obtain solution B; 3) Add solution B dropwise to solution A, completing the addition within 10-60 min; 4) After separation, washing, and drying, obtain the few-layer amorphous chalcogenides. The few-layer amorphous chalcogenides obtained by the above technical solution of this invention can be used for piezoelectric catalysis, photo-piezoelectric catalytic cracking of water for hydrogen and oxygen production, and degradation of organic pollutants in water bodies.

Description

Technical Field

[0001] This invention provides a general method for in-situ chemical tailoring to prepare few-layer amorphous chalcogenides, thereby obtaining piezoelectric catalysts and photo-piezoelectric catalysts with excellent piezoelectric properties for efficient water splitting to produce hydrogen and oxygen, and for degrading organic pollutants in water bodies. This invention belongs to the field of inorganic non-metallic materials technology. Background Technology

[0002] With the rapid development of the human economy and the high-speed advancement of social industrialization, organic pollutants from chemical waste, pharmaceutical waste, pesticide residues, and personal care products are discharged into aquatic environments with wastewater, posing a serious threat to ecosystems and human health. These organic pollutants are characterized by their complexity, stable structure, strong biotoxicity, significant potential hazards, and difficulty in being effectively treated by traditional physical, chemical, or biological methods. Therefore, protecting clean water sources and efficiently degrading organic pollutants in wastewater has become a pressing issue. In recent decades, photocatalysis technology, as a highly promising water purification method, has been extensively explored by researchers. To utilize natural light energy more efficiently, numerous catalyst modification methods, such as the construction of heterojunction structures, doping with metals and non-metals, deposition of precious metals, and the addition of supports, have been thoroughly investigated. However, one of the biggest obstacles to the commercialization of photocatalysis technology remains the low degradation efficiency due to the limited utilization of light energy. Piezoelectric catalysis, because it does not require light energy input, has become a feasible method to alleviate the bottleneck of light energy utilization in photocatalysts. Studies have found that piezoelectric materials can directly convert mechanical energy from the environment into chemical energy, effectively overcoming the limitations of photocatalysis technology. Although significant progress has been made in piezoelectric catalysis and photo-piezoelectric catalysis in recent years, problems such as low mechanical energy conversion efficiency and a limited number of available candidate materials still exist. Therefore, the development of novel piezoelectric materials with high piezoelectric coefficients and high elastic moduli is urgently needed.

[0003] Layered chalcogenides are considered ideal candidates for piezoelectric catalysis due to their unique layered structure, high aspect ratio, high charge mobility, and abundant surface active sites. Unfortunately, the high catalytic activity of layered chalcogenides is only manifested on the surface of monolayer or few-layer structures. For bulk chalcogenides with multilayer structures, the catalytic activity decreases sharply. Currently, the strategies for constructing monolayer or few-layer chalcogenides mainly include top-down and bottom-up methods. The top-down method can be understood as the exfoliation of bulk crystals, mainly including mechanical methods, solvent methods, ion intercalation methods, and ion intercalation-assisted methods. Vapor deposition and epitaxial growth are the main methods of the bottom-up method, mainly including precursor thermal decomposition, physical vapor deposition, and chemical vapor deposition. However, the production of monolayer or few-layer materials using the above strategies still suffers from problems such as expensive equipment, complex operation, and harsh reaction conditions. At the same time, the size of the prepared monolayer or few-layer materials is severely limited by the substrate size, and the loss of quality and performance during material detachment and transfer from the substrate cannot be avoided. Therefore, it is crucial to develop new methods that are simple, efficient, and have mild reaction conditions.

[0004] Coprecipitation is a promising material synthesis method due to its simplicity, speed, and ability to significantly improve economic efficiency and resource utilization. By controlling reaction conditions and achieving in-situ chemical tailoring during the preparation of chalcogenides via coprecipitation, few-layer amorphous chalcogenides with high mechanical conversion rates, high surface curvature, and abundant exposed edge sites can be synthesized. These compounds can be used for hydrogen and oxygen production from water pyrolysis and for the efficient degradation of organic pollutants in water. The implementation of this patent will promote the development of piezoelectric catalysts in piezoelectric and photo-piezoelectric catalysis technologies and facilitate the comprehensive integration and interdisciplinary collaboration of multiple disciplines. Summary of the Invention

[0005] The present invention provides an in-situ chemical tailoring method for preparing few-layer amorphous chalcogenides. The basic idea is to utilize the surface cleavage of layered chalcogenides under alkaline conditions, while simultaneously applying relative strain in the reaction solution, thereby achieving crystal segmentation and thinning. By controlling the reaction conditions, controllable preparation of few-layer amorphous chalcogenide piezoelectric materials can be achieved.

[0006] The present invention provides a method for preparing few-layer amorphous chalcogenides, the main technical solution of which is as follows:

[0007] 1) Dissolve 1–10 mmol of reagent A in 40 mL of alkaline solution to obtain solution A;

[0008] 2) Dissolve 3–30 mmol of reagent B in 40 mL of citric acid solution to obtain solution B;

[0009] 3) Add solution B dropwise to solution A, completing the addition within 10–60 minutes;

[0010] 4) After separation, washing and drying, a few-layer amorphous chalcogenide compounds are obtained.

[0011] In the above technical solution of the present invention, the alkaline reagent used in step 1) is one or a combination of KOH, NaOH and LiOH, and its concentration is 1 to 9 mol / L.

[0012] In the above technical solution of the present invention, the reagent A used in step 1) is one or a combination of several of CH4NaS, CH4N2S, SeO2, and Se powder.

[0013] In the above technical solution of the present invention, the reagent B used in step 2) is one of Na2MoO4·2H2O, Na2WO4·2H2O, GeO2 powder, and SnCl2·2H2O.

[0014] In the above technical solution of the present invention, the concentration of citric acid used in step 2) is 1-30 mol / L.

[0015] In the above technical solution of the present invention, the washing solvent used in step 4) is one or a combination of deionized water, anhydrous ethanol, ethylene glycol, acetone and methanol.

[0016] In the above technical solution of the present invention, the obtained few-layer amorphous chalcogenide can be used as a catalyst for piezoelectric catalysis, photo-piezoelectric catalysis of water splitting to produce hydrogen and oxygen, and degradation of organic pollutants in water.

[0017] In the above technical solutions of the present invention, the purity of all chemical reagents used is not lower than that of analytical grade.

[0018] The beneficial effects of this invention are as follows: The method provided by this invention enables the preparation of few-layer amorphous chalcogenides. The obtained few-layer amorphous chalcogenides have a typical amorphous phase structure, with nanoparticles extending to several micrometers. Studies have shown that the few-layer amorphous chalcogenides prepared by this method are chemically tailored into a few-layer structure in situ, with a piezoelectric coefficient reaching 124.596 pm / V. Their amorphous structure has more unsaturated active sites, which can effectively degrade organic pollutants in water, and achieve complete degradation of Rhodamine B dye (10 mg / L) within 60 minutes under magnetic stirring. The method provided by this invention is simple, easy to operate, has mild reaction conditions, low energy consumption, low preparation cost, and can achieve mass production. Attached Figure Description

[0019] Figure 1 These are SEM images of representative samples.

[0020] Figure 2 TEM images of representative samples

[0021] Figure 3 This is the XRD pattern of a representative sample.

[0022] Figure 4 These are loop images of a) morphology, b) phase, c) amplitude, and d) phase-amplitude of a representative sample.

[0023] Figure 5 This is an evaluation of the piezoelectric catalytic performance of representative samples. Detailed Implementation

[0024] Example 1

[0025] Preparation of few-layer amorphous chalcogenides by coprecipitation method

[0026] 1) Dissolve 1 mmol CH4NaS in 40 mL of 1 mol / L KOH solution to obtain solution A;

[0027] 2) Dissolve 5 mmol Na2MoO4·2H2O in 40 mL of 22 mol / L citric acid solution to obtain solution B;

[0028] 3) Add solution B dropwise to solution A, completing the addition within 10 minutes;

[0029] 4) Separate the solid and liquid phases of the product obtained in 3), wash it alternately with deionized water, ethylene glycol and acetone until neutral, and dry it to obtain a few-layer amorphous phase MoS2.

[0030] Example 2

[0031] Preparation of few-layer amorphous chalcogenides by coprecipitation method

[0032] 1) Dissolve 3 mmol CH4N2S in 40 mL of 5 mol / L NaOH solution to obtain solution A;

[0033] 2) Dissolve 10 mmol Na2WO4·2H2O in 40 mL of 17 mol / L citric acid solution to obtain solution B;

[0034] 3) Add solution B dropwise to solution A, completing the addition within 20 minutes;

[0035] 4) Separate the solid and liquid phases of the product obtained in 3), wash it alternately with deionized water and anhydrous ethanol until neutral, and dry it to obtain the few-layer amorphous phase WS2.

[0036] Example 3

[0037] Preparation of few-layer amorphous chalcogenides by coprecipitation method

[0038] 1) Dissolve 5 mmol SeO2 and 5 mmol Se powder in 40 mL of 9 mol / L LiOH solution to obtain solution A;

[0039] 2) Dissolve 10 mmol Na2MoO4·2H2O in 40 mL of 9 mol / L citric acid solution to obtain solution B;

[0040] 3) Add solution B dropwise to solution A, completing the addition within 15 minutes;

[0041] 4) Separate the solid and liquid phases of the product obtained in 3), wash it alternately with deionized water and methanol until neutral, and dry it to obtain the few-layer amorphous phase MoSe2.

[0042] Example 4

[0043] Preparation of few-layer amorphous chalcogenides by coprecipitation method

[0044] 1) Dissolve 1.6 mmol of Se powder in 40 mL of 5 mol / L NaOH solution to obtain solution A;

[0045] 2) Dissolve 5 mmol Na2WO4·2H2O in 40 mL of 7 mol / L citric acid solution to obtain solution B;

[0046] 3) Add solution B dropwise to solution A, completing the addition within 60 minutes;

[0047] 4) Separate the solid and liquid phases of the product obtained in 3), wash it alternately with deionized water and acetone until neutral, and dry it to obtain the few-layer amorphous phase WSe2.

[0048] Example 5

[0049] Preparation of few-layer amorphous chalcogenides by coprecipitation method

[0050] 1) Dissolve 2 mmol CH4NaS and 5 mmol CH4N2S in a mixed solution of 20 mL 3 mol / L NaOH and 20 mL 6 mol / L KOH to obtain solution A;

[0051] 2) Dissolve 30 mmol of GeO2 powder in 40 mL of 17 mol / L citric acid solution to obtain solution B;

[0052] 3) Add solution B dropwise to solution A, completing the addition within 50 minutes;

[0053] 4) Separate the solid and liquid phases of the product obtained in 3), wash it alternately with deionized water and ethylene glycol until neutral, and dry it to obtain a few-layer amorphous phase GeS.

[0054] Example 6

[0055] Preparation of few-layer amorphous chalcogenides by coprecipitation method

[0056] 1) Dissolve 2 mmol CH4N2S in a mixed solution of 10 mL 2 mol / L NaOH and 30 mL 2 mol / L LiOH to obtain solution A;

[0057] 2) Dissolve 30 mmol SnCl2·2H2O in 40 mL of 25 mol / L citric acid solution to obtain solution B;

[0058] 3) Add solution B dropwise to solution A, completing the addition within 45 minutes;

[0059] 4) Separate the solid and liquid phases of the product obtained in 3), wash it alternately with deionized water, methanol and acetone until neutral, and dry it to obtain a few-layer amorphous phase SnS.

[0060] Example 7

[0061] Preparation of few-layer amorphous chalcogenides by coprecipitation method

[0062] 1) Dissolve 2 mmol SeO2 in 40 mL of 2 mol / L KOH solution to obtain solution A;

[0063] 2) Dissolve 15 mmol of GeO2 powder in 40 mL of 5 mol / L citric acid solution to obtain solution B;

[0064] 3) Add solution B dropwise to solution A, completing the addition within 25 minutes;

[0065] 4) Separate the solid and liquid phases of the product obtained in 3), wash it alternately with deionized water, methanol and ethylene glycol until neutral, and dry it to obtain a few-layer amorphous phase GeSe.

[0066] Example 8

[0067] Preparation of few-layer amorphous chalcogenides by coprecipitation method

[0068] 1) Dissolve 1.2 mmol of Se powder in 40 mL of 3 mol / L NaOH solution to obtain solution A;

[0069] 2) Dissolve 4 mmol SnCl2·2H2O in 40 mL of 17 mol / L citric acid solution to obtain solution B;

[0070] 3) Add solution B dropwise to solution A, completing the addition within 30 minutes;

[0071] 4) Separate the solid and liquid phases of the product obtained in 3), wash it alternately with deionized water, anhydrous ethanol and methanol until neutral, and dry it to obtain a few-layer amorphous phase SnSe.

[0072] Figure 1 The image shows an SEM image of the amorphous layered chalcogenide prepared by the coprecipitation method in the example. As can be seen from the image, the obtained amorphous layered chalcogenide exhibits a granular morphology, with its nanoparticles stacked and extended to several micrometers.

[0073] Figure 2 The image shows a TEM image of the amorphous layered chalcogenides prepared by the coprecipitation method in the examples. As can be seen from the image, the synthesized sample has a thinner active edge, indicating that in-situ chemical trimming was successfully achieved under alkaline conditions.

[0074] Figure 3 The XRD pattern of the amorphous layered chalcogenide prepared by precipitation method in the example is shown in the figure. As can be seen from the figure, the diffraction peaks of the synthesized sample are weak and broad, showing an obvious amorphous phase structure.

[0075] Figure 4 The figures show the a) morphology, b) phase, c) amplitude, and d) phase-amplitude loop images of the amorphous layered chalcogenides prepared by precipitation method in the examples. As can be seen from the figures, the detection of a typical butterfly curve in the lateral direction indicates that the synthesized sample has in-plane piezoelectricity / ferroelectricity, and its piezoelectric coefficient reaches 124.596 pm / V, indicating that the synthesized sample has a high mechanical conversion rate.

[0076] Figure 5 This example demonstrates the performance evaluation of the degradation of Rhodamine B dye by amorphous layered chalcogenides prepared by precipitation method under magnetic stirring. As shown in the figure, the amorphous layered chalcogenides, possessing high piezoelectricity and abundant surface sites, can achieve a 100% degradation efficiency of Rhodamine B dye within 60 minutes. This is fundamentally different from the synthesis of monolayer or few-layer chalcogenides through methods such as exfoliation and deposition in existing technologies.

Claims

1. A method for preparing chalcogenides, achieving in-situ chemical tailoring to obtain few-layer amorphous chalcogenides, characterized in that... The process includes the following steps: 1) Dissolve 1–10 mmol of reagent A in 40 mL of alkaline solution to obtain solution A; 2) Dissolve 3–30 mmol of reagent B in 40 mL of citric acid solution to obtain solution B; 3) Add solution B dropwise to solution A, completing the addition within 10–60 minutes; 4) After separation, washing, and drying, a few-layer amorphous chalcogenide compounds are obtained; Its characteristics include: the alkaline solution used is one or a combination of KOH, NaOH, and LiOH, with a concentration of 1–9 mol / L; reagent A used is one of CH4NaS, CH4N2S, SeO2, and Se powder; reagent B used is one of Na2MoO4·2H2O, Na2WO4·2H2O, GeO2 powder, and SnCl2·2H2O; and the citric acid concentration is 1–30 mol / L.

2. The method for preparing chalcogenides according to claim 1, characterized in that... The few-layer amorphous chalcogenides include MoS2, WS2, MoSe2, WSe2, GeS, SnS, GeSe, or SnSe.

3. The method for preparing chalcogenides according to claim 1, characterized in that... Applications of the few-layer amorphous chalcogenides in piezoelectric catalysis, photo-piezoelectric catalysis of water splitting for hydrogen and oxygen production, and degradation of organic pollutants.

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