A heterojunction composite material Co 1-x Preparation methods of S / MoS2 and its application in sulfide detection

Abstract

This invention belongs to the field of materials synthesis and analysis, specifically relating to a heterojunction composite material Co. 1‑x Preparation method of S / MoS2 and its application in sulfide detection. This invention is the first to apply three-dimensional Co... 1‑x Two-dimensional MoS2 nanosheets were grown in situ on S nanocubes to prepare a 3D / 2D heterostructure composite material Co. 1‑x S / MoS2. Compared to the original C o1‑x Compared to S and MoS2, the obtained Co has a 3D / 2D heterostructure 1‑x The peroxidase catalytic activity of S / MoS2 is significantly enhanced. In the presence of sulfide ions, Co... 1‑x The peroxidase catalytic activity of S / MoS2 can be selectively inhibited, thereby enabling the development of a Co-based... 1‑x A colorimetric detection method catalyzed by S / MoS2 nanozymes is used for the detection of sulfur ions in environmental water samples, and it has high specificity.

Description

Technical Field

[0001] This invention belongs to the field of materials synthesis and analysis, specifically relating to a heterojunction composite material Co. 1-x Preparation method of S / MoS2 and the resulting product, and its application in colorimetric detection of sulfides. Background Technology

[0002] Sulfide ions, as toxic pollutants, are prevalent in aquatic environments due to the widespread use of sulfides in sulfuric acid and sulfur production, as well as their application in cosmetics, dyes, and other industries. Human exposure to high concentrations of sulfur dioxide (S₂) can lead to serious health problems. 2- Sulfide ions pose a serious threat to health and can trigger various diseases, including cirrhosis, diabetes, and even Alzheimer's disease. Therefore, developing simple and rapid methods to determine sulfide ion levels is crucial. Currently, several analytical methods have been reported for the detection of sulfide ions, including fluorescence, chromatography, electrochemistry, and colorimetry. Among these analytical techniques, colorimetry is receiving increasing attention due to its simplicity, ease of use, and optical properties.

[0003] In recent years, various catalytically active nanozymes have been widely used in disease analysis and environmental monitoring. Compared with natural enzymes, they have advantages such as low cost, ease of operation, and superior stability. In particular, as a representative of nanozymes, two-dimensional molybdenum disulfide (MoS2), which exhibits enzyme-mimicking behavior, has been widely used for the quantitative detection of environmental pollutants, including pesticides, antibiotics, and metal ions. However, most MoS2 nanozymes still face the key problem of poor catalytic performance, hindering their potential application in analytical fields. To overcome these limitations, various strategies have been adopted to modulate the catalytic behavior of the obtained MoS2 nanozymes, including surface treatment, elemental doping, or the construction of composite nanomaterials.

[0004] Three-dimensional (3D) cobalt-sulfur nanocubes (Co) possess attractive properties such as high surface area, large internal space, and excellent photo / electrocatalytic performance. 1-x Molybdenum disulfide nanosheets (MoS2NSs) have been extensively studied in the fields of energy, environment, and catalysis. However, there are currently no reports on the preparation of mixed nanozymes with enhanced catalytic activity for the colorimetric determination of sulfide ions by in-situ synthesis of two-dimensional (2D) molybdenum disulfide nanosheets (MoS2NSs) on Co1-xS NCs. Summary of the Invention

[0005] To address the research and development gaps in existing technologies, this invention provides a heterojunction composite material Co 1-x A method for preparing S / MoS2. This method involves a one-pot hydrothermal process to prepare three-dimensional Co... 1-xA highly efficient heterojunction nanozyme was synthesized by in-situ growth of two-dimensional MoS2 nanosheets (NSs) on S nanocubes.

[0006] This invention further provides a heterojunction composite material Co prepared using the above method. 1-x S / MoS2.

[0007] Another object of the present invention is to provide the above-mentioned heterojunction composite material Co 1-x Application of S / MoS2 in colorimetric detection of sulfides.

[0008] The technical solution adopted by the present invention to achieve the above objectives is as follows: This invention provides a heterojunction composite material Co 1-x The preparation method of S / MoS2 includes the following steps: (1) Dissolve Co(NO3)2·6H2O and CTAB in distilled water, then quickly pour the above solution into an aqueous solution containing 2-methylimidazole and stir vigorously at room temperature; collect the precipitate by centrifugation, wash and dry to obtain ZIF-67 NCs; (2) ZIF-67 NCs were added to ethanol under ultrasonication to form a homogeneous suspension; then, thioacetamide (TAA) was added to the suspension and stirred vigorously; the resulting mixture was then heated to react; after cooling to room temperature, the resulting precipitate was washed and dried to obtain Co. 1-x S NCs; (3) Co 1-x SNCs and molybdenum source were added to deionized water and stirred for 10 minutes. Then, the sulfur source was added to the mixed suspension and stirred again. Subsequently, the resulting mixture was placed in a PTFE-lined autoclave (50 mL capacity) for reaction. After cooling to room temperature, the obtained Co was washed with an ethanol-water mixture. 1-x S / MoS2 hybrid nanozymes.

[0009] Preferably, in step (1), the mass ratio of Co(NO3)2·6H2O, CTAB and 2-methylimidazole is 58:1:900-910; the concentration of the 2-methylimidazole aqueous solution is 64-65 mg / mL; and the stirring time is 20-30 minutes.

[0010] Preferably, in step (2), the concentration of ZIF-67 NCs in ethanol is 1.5-2.0 mg / mL; the mass ratio of ZIF-67 NCs to thioacetamide is 1:1; the vigorous stirring time is 10 minutes; and the reaction is maintained at 175-185°C for 3.0 hours.

[0011] Preferably, in step (3), the molybdenum source is sodium molybdate dihydrate; the sulfur source is L-cysteine; the mass ratio of Co1-xS NCs to the molybdenum source is 1:1; the molar ratio of the molybdenum source to the sulfur source is 0.35:1.5; the Co 1-x S NCs are hollow nanocubes.

[0012] Preferably, in step (3), the reaction is carried out at 200°C for 24 hours.

[0013] This invention also provides a heterojunction composite material Co prepared by the above preparation method. 1-x S / MoS2.

[0014] Another object of the present invention is to provide the above-mentioned heterojunction composite material Co 1-x Application of S / MoS2 in colorimetric detection of sulfides.

[0015] Co prepared by this invention 1-x S / MoS2, with single Co 1-x Compared to S and MoS2, the resulting Co exhibits a three-dimensional / two-dimensional (3D / 2D) heterostructure. 1-x S / MoS2 exhibits significantly enhanced peroxidase-mimicking catalytic activity, attributed to the 3D / 2D interface coupling formed within the heterostructure promoting charge transport in the catalytic reaction. Furthermore, the peroxidase-mimicking catalytic behavior of the prepared hybrid nanozyme is selectively inhibited in the presence of sulfide ions, as sulfide ions compete with the enzyme substrate for •OH radicals and reduce the oxidized substrate. Therefore, this invention proposes a catalysis-based, highly efficient colorimetric detection method for the quantitative detection of sulfides in environmental water samples. Benefiting from the synergistic effect between the two components and the accelerated electron transfer of the prepared hybrid nanozyme, the constructed catalysis-based colorimetric detection method achieves a wide linear range and low detection limit when detecting sulfide ions. This invention is the first to report the use of Co... 1-x In-situ growth of MoS2 nanosheets on S nanocubes to prepare composite nanozymes with three-dimensional / two-dimensional heterostructures, in order to develop a colorimetric analysis method for the detection of sulfides in environmental water based on catalysis.

[0016] The beneficial effects of this invention are: this invention is the first to utilize three-dimensional Co... 1-x Two-dimensional MoS2 nanosheets were grown in situ on S nanocubes to prepare a 3D / 2D heterostructure composite material Co. 1-x S / MoS2. With a single C o1-x Compared to S and MoS2, the obtained Co has a 3D / 2D heterostructure 1-x The peroxidase catalytic activity of S / MoS2 is significantly enhanced. In the presence of sulfide ions, Co...1- x The peroxidase catalytic activity of S / MoS2 can be selectively inhibited, thereby enabling the development of a Co-based... 1-x A colorimetric detection method catalyzed by S / MoS2 nanozymes is used for the detection of sulfur ions in environmental water samples, and it has high specificity. Attached Figure Description

[0017] Figure 1 For Co 1-x Preparation process of S / MoS2 (A) and Co-based 1-x Schematic diagram of the catalytic principle of S / MoS2 detection of S²⁻ (B); Figure 2 Scanning electron microscope (SEM) images of different samples: ZIF-67 precursor (A), Co 1-x S (B), Co at different magnifications 1-x S / MoS2(C, D); Figure 3 For Co 1-x Transmission electron microscopy (TEM) image (A) of S / MoS2, its high-magnification TEM image (B), and MoS2 (C), Co 1-x Local magnified region of S(D); Figure 4 To obtain MoS2, Co 1-x S and Co 1-x The UV-Vis absorption spectrum (A) and catalytic performance comparison (B) of the TMB-H2O2 reaction solution under the action of S / MoS2 nanozyme are shown, along with actual photos of the corresponding test solutions. Figure 5 Co is the condition for the presence or absence of S²⁻. 1-x UV-Vis absorption spectra of S / MoS2 and MoS2 catalyzing the TMB-H2O2 reaction (A) and comparison of catalytic performance (B); Figure 6 For Co-based 1-x The colorimetric selectivity of S²⁻ for S / MoS₂, from left to right, is as follows: Cl⁻, Ac⁻, SO₄²⁻, CO₃²⁻, HCO₃⁻, I⁻, HPO₄²⁻, H₂PO₄⁻, NO₃⁻, K⁺, Br⁻, Na⁺, Ca²⁺, Mg²⁺, S²⁻; Figure 7 For Co-based 1-x UV-Vis absorption spectra of S²⁻ ions at different concentrations (a→g: 0.1, 0.5, 5, 10, 20, 40, 50 μM) for colorimetric detection of S / MoS₂ (A); standard curves of absorbance difference versus S²⁻ concentration (0.1~50 μM) (B); Figure 8 For Co 1-x Optimization of reaction conditions for S / MoS2 peroxidase activity; including temperature (A), pH value (B), ionic strength (C), and environmental stability (D). Detailed Implementation

[0018] The technical solution of the present invention will be further explained and described below through specific embodiments.

[0019] Example 1 (1) Synthesis of ZIF-67 NCs ZIF-67 NCs were prepared using a surfactant-mediated hydrothermal method. Co(NO3)2·6H2O (58 mg) and CTAB (1.0 mg) were dissolved in 2.0 mL of distilled water. This solution was then rapidly poured into a 14 mL aqueous solution containing 2-methylimidazole (908 mg), and stirred at room temperature and 1500 rpm for 20 minutes. The resulting purple precipitate was collected by centrifugation, washed several times with an ethanol-water mixture, and then dried via a freeze-drying process. (2) Synthesis of Co 1-x S NCs First, the ZIF-67 obtained in step (1) was added to 50 mL of ethanol under ultrasonication and mixed thoroughly for several minutes to obtain a homogeneous suspension (concentration of 1.6 mg / mL). Then, thioacetamide (TAA, 80 mg) was added to the suspension and stirred vigorously for 10 minutes. Afterward, the resulting mixture was placed in a 70 mL polytetrafluoroethylene-lined autoclave and kept at 180°C for 3.0 hours. After cooling to room temperature, the precipitate was washed several times with an ethanol-water mixture (ethanol to water volume ratio of 1:1), and then dried via a freeze-drying process for 24 hours to obtain hollow Co. 1-x S-Nano Cubes (NCs) Products.

[0020] (3) Synthesis of Co 1-x S / MoS2 Co 1-x S / MoS2 is prepared by a one-pot hydrothermal method, such as... Figure 1 As shown in A. Co 1-x S nanocubes (50 mg) and sodium molybdate dihydrate (0.35 mmol) were added to 35 mL of deionized water and stirred for 10 minutes. Then, a certain amount of L-cysteine ​​(1.5 mmol) was added to the suspension and stirred for another 10 minutes. The resulting mixture was then placed in a 50 mL PTFE-lined autoclave and maintained at 200°C for 24 hours. After cooling to room temperature, the obtained Co was washed with an ethanol-water mixture.1-x S / MoS2, freeze-dried for later use.

[0021] Co with a 3D / 2D heterostructure was prepared by a one-pot hydrothermal method as described in Example 1. 1-x S / MoS2 heterojunction composite nanozymes. The morphology of the prepared material was first characterized using field emission scanning electron microscopy (SEM). Figure 2 ).from Figure 2 As can be seen from Figure A, the prepared ZIF-67 precursor exhibits a well-defined cubic morphology and a smooth surface. The Co generated after sulfurization treatment... 1-x S nanocubes can inherit the overall morphology of the ZIF-67 precursor, but their surface is relatively rough. Figure 2 B). The generated Co can be observed as marked by the red dashed circle. 1-x S nanocubes exhibit an internally hollow structure. Co 1-x SEM images of S / MoS2 are displayed in Figure 2 In CD. A large number of MoS2 nanosheets are uniformly distributed in Co. 1-x S nanocubes were formed to create Co with a 3D / 2D heterostructure. 1-x S / MoS2.

[0022] To further investigate the microstructure of the prepared samples, high-resolution transmission electron microscopy (HRTEM) was used, and the data are as follows: Figure 3 As shown, layered MoS2 nanosheets with twisted edges are uniformly and evenly distributed on Co. 1-x S nanocubic surface, thus forming Co 1-x S / MoS2 heterojunction composite material ( Figure 3 AB). Furthermore, through Co 1-x The stark contrast between the S-shaped outer shell and the hollow interior, Co 1-x The internal cavity of the S nanocube. Furthermore, Co... 1-x Magnified image of the MoS2 portion in S / MoS2 ( Figure 3 C) shows a distinct lattice spacing of 0.628 nm, which corresponds to the (002) plane of MoS2. In contrast, Figure 3 D is Co 1-x A magnified view of a localized region of S nanocrystals reveals two distinct lattice fringes with values ​​of 0.29 and 0.19 nm, corresponding to hexagonal Co nanocrystals, respectively. 1-x The (110) and (102) crystal planes of S.

[0023] Example 1 (a) Co 1-x Peroxidase-mimicking behavior of S / MoS2 (1) Peroxidase catalytic activity Disperse appropriate amounts of nanozymes of different concentrations in 0.1 M acetate buffer at pH 4.0, then add 10 μL LTMB (25 mM) and 2 μL H2O2 (5.0 M), incubate the mixture at room temperature for 20 minutes, transfer it to a 96-well plate, and record the absorbance at 652 nm using a microplate reader; transfer it to a cuvette and measure the UV-Vis absorption spectrum from 450 to 800 nm using a UV-Vis spectrophotometer.

[0024] When optimizing catalytic conditions using the controlled variable method and evaluating the effects of temperature or pH on catalytic activity, Co... 1-x S / MoS2 was treated at temperatures ranging from 4 °C to 60 °C, or at room temperature with different buffer solutions ranging from pH 2.5 to pH 7. After catalysis in the reaction system for 20 minutes, the absorbance at 652 nm was measured using an enzyme-linked immunosorbent assay (ELISA) reader.

[0025] The colorimetric reaction between catalytic TMB and H2O2 was used to evaluate the Co content. 1-x Peroxidase-mimicking performance of S / MoS2 nanozymes, and compared with single Co 1-x S nanocubes and MoS2 nanosheets were compared. The catalytic reaction conditions were optimized by varying the nanozyme concentration, pH, reaction temperature, and substrate concentration.

[0026] Nanozyme concentrations: 10, 20, 40, 60, 80, 100 μg / mL Temperature: 4, 25, 37, 45, 55, 65℃ pH: 2, 3, 4, 5, 6, 7, 8, 9, 10 NaCl: 0, 50, 100, 150, 200, 250, 300 mM The colorimetric analysis of Co with a 3D / 2D heterostructure was performed using an oxidation reaction of TMB and hydrogen peroxide. 1-x Peroxidase-mimicking catalytic activity of S / MoS2. For example... Figure 4 As shown in A, a single Co 1-x S and MoS2 exhibited poor peroxidase-mimicking catalytic performance. When MoS2 nanosheets were deposited onto Co... 1-x After S, the obtained Co 1-x S / MoS2 exhibited significantly enhanced peroxidase-mimicking catalytic activity. Furthermore, bar charts of the absorption intensity of TMB-H2O2 reaction solutions for different samples and corresponding images of the reaction solutions were presented. Figure 4 B), which can intuitively display Co 1-xThe significant improvement in the catalytic performance of S / MoS2 nanozymes is likely due to the synergistic effect between the two components and the 3D / 2D interface interaction formed in the heterostructure. This provides more reaction centers and promotes more charge transfer in the catalytic reaction.

[0027] By varying the solution temperature, pH value, and ionic strength in the sodium chloride concentration, this invention determined the optimal catalytic conditions. Figure 8 The obtained Co 1-x S / MoS2 exhibited the best catalytic behavior at a solution temperature of 25°C and a pH of 4.0. Figure 8 AB). Furthermore, even at a sodium chloride concentration of 300 mM, Co 1-x The catalytic performance of S / MoS2 remains largely unchanged. Figure 8 C), indicating that its catalytic performance remains stable under high salt concentration conditions. Finally, the prepared Co was also tested. 1-x The environmental stability of S / MoS2 heterojunction composites was explored. Figure 8 D). Even after storage for more than six months, its catalytic performance did not change significantly, verifying that the obtained hybrid nanozyme has excellent environmental stability over time.

[0028] (ii) Colorimetric detection of sulfide ions Specific steps for detecting sulfide ions: In the presence of Co 1-x S / MoS2 nanozymes, TMB-H2O2 substrates, and different concentrations of S 2- In the acetate reaction system of ions, S was carried out. 2- Colorimetric detection of ions. Specifically: Take an appropriate amount of Co... 1-x The S / MoS2 nanozyme was dispersed in 0.1 M acetate buffer at pH 4.0, 10 μL of TMB (25 mM) and 2 μL of H2O2 (5.0 M) were added, followed by 50 μL of S²⁻ at different concentrations. The mixture was incubated at 25°C for 20 minutes, transferred to a 96-well plate, and the absorbance at 652 nm was recorded using a microplate reader.

[0029] To further explore the detection of S using a colorimetric platform based on nanozyme catalysis 2- The ion selectivity was assessed using the same steps described above, with the addition of a potential interfering substance (Cl at a concentration of 0.01 mM) to the system. - Ac - SO4 2- CO3 2- HCO3 - , I - HPO4 2- H2PO4 -NO3 - , K + , Br - Na + Ca 2+ Mg 2+ ) to replace S 2- After incubation for 20 minutes, the sample was transferred to a 96-well plate and the absorbance at 652 nm was recorded using a microplate reader.

[0030] This invention constructs a Co-based 1-x The S / MoS2 catalytic detection platform quantitatively analyzes S by monitoring changes in the absorbance intensity of the reaction products in the catalytic colorimetric reaction system. 2- Ions are reasonable ( Figure 5 Compared to MoS2, the obtained nanozymes showed better performance with the addition of S. 2- The absorbance intensity decreased significantly afterward. Figure 5 (AB), which indicates that a method for S can be established. 2- The colorimetric detection method for analysis. Furthermore, from... Figure 7 As can be seen from A, the absorbance intensity of the oxidation product of TMB at 652 nm gradually decreases with increasing sulfide ion concentration from 0.10 to 50.0 μM. Correspondingly, Figure 7 B plots calibration curves for absorbance intensity versus different sulfide ion concentrations. Clearly, there is a linear relationship between the absorbance difference (A0-A) and the sulfide ion concentration (range 0.10 to 50.0 μM), with the equation y = 0.0122x + 0.1148 (R²). 2 = 0.9865). Furthermore, the lowest detection limit of this analytical method was estimated to be 0.021 μM using the 3σ rule, which is far below the maximum permissible concentration of sulfide ions in drinking water defined by the World Health Organization (15 μM).

[0031] Furthermore, selectivity is an important parameter for evaluating the analytical performance of the proposed analytical method. To evaluate the Co-based... 1-x S / MoS2 nanozyme catalytic colorimetric platform for the detection of S 2- The selectivity of ions, the addition of potential interfering substances to the catalytic system, including Cl... - Ac - SO4 2- CO3 2- HCO3 - , I - HPO4 2- H2PO4 - NO3 - , K + , Br - Na +Ca 2+ Mg 2+ .from Figure 6 As can be seen, the introduction of these interfering ions did not significantly change the absorbance of the system, verifying the effectiveness of the proposed analytical method for detecting S. 2- Ions have high anti-interference ability.

[0032] This invention successfully prepared Co with 3D / 2D structures via a hydrothermal synthesis method. 1-x S / MoS2 heterojunction composite nanozymes. Studies have shown that Co... 1-x S / MoS2 exhibits significantly enhanced catalytic behavior compared to single materials, likely due to synergistic effects between the two components, accelerated electron transport in the heterostructure, and high affinity for the substrate. Based on the obtained Co... 1-x S / MoS2 exhibits excellent peroxidase-mimicking catalytic behavior, and S 2- Competitive inhibition of nanozyme catalytic activity was investigated, and a method for quantitative analysis of S was established. 2- This invention relates to a colorimetric detection platform for ions, which features a wide linear range and a low detection limit. The platform utilizes a three-dimensional hollow Co... 1-x Two-dimensional molybdenum disulfide nanosheets were synthesized in situ on S nanocubes to construct three-dimensional / two-dimensional heterojunction composite nanozymes, thereby improving the peroxidase catalytic performance of molybdenum disulfide. This method shows great promise in the detection of sulfides in water quality safety assessment.

Claims

1. A heterojunction composite material Co 1-x The method for preparing S / MoS2 is characterized by, Includes the following steps: (1) Dissolve Co(NO3)2·6H2O and CTAB in distilled water, then quickly pour the above solution into an aqueous solution containing 2-methylimidazole and stir to carry out the reaction; collect the precipitate by centrifugation, wash and dry to obtain ZIF-67 NCs; (2) Add ZIF-67 NCs to ethanol to form a homogeneous suspension; Subsequently, thioacetamide (TAA) was added to the suspension and stirred vigorously; then, the resulting mixture was heated to react; after cooling to room temperature, the resulting precipitate was washed and dried to obtain Co. 1-x S NCs; (3) Co 1-x SNCs and molybdenum source were added to deionized water and stirred. Then, sulfur source was added to the mixed suspension and stirred until homogeneous. The resulting mixture was reacted, cooled to room temperature, and washed to obtain Co. 1-x S / MoS2 heterojunction composite nanozyme.

2. The preparation method according to claim 1, characterized in that, In step (1), the mass ratio of Co(NO3)2·6H2O, CTAB and 2-methylimidazole is 58:1:900-910; the concentration of the 2-methylimidazole aqueous solution is 64-65 mg / mL; and the stirring is carried out at room temperature for 20-30 minutes.

3. The preparation method according to claim 1 or 2, characterized in that, In step (2), the concentration of ZIF-67 NCs in ethanol is 1.5-2.0 mg / mL; the mass ratio of ZIF-67 NCs to thioacetamide is 1:1; the vigorous stirring time is 10 minutes; and the reaction is maintained at 175-185℃ for 3.0 hours.

4. The preparation method according to any one of claims 1-3, characterized in that, In step (3), the molybdenum source is sodium molybdate dihydrate; the sulfur source is L-cysteine; and the Co... 1-x The mass ratio of SNCs and molybdenum source is 1:1; the molar ratio of molybdenum source to sulfur source is 0.35:1.5; the Co... 1-x S NCs are hollow nanocubes.

5. The preparation method according to claim 4, characterized in that, In step (3), the reaction is carried out at 200°C for 24 hours.

6. A heterojunction composite material Co prepared by the preparation method according to any one of claims 1-5 1-x S / MoS2.

7. A heterojunction composite material Co as described in claim 6 1-x Application of S / MoS2 in colorimetric detection of sulfides.

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