A MoS2 / ZIF-67 core-shell material, its preparation method, and its applications.

Abstract

The application discloses a kind of MoS2 / ZIF-67 core-shell materials, MoS2 / ZIF-67 core-shell material is cubic, MoS2 Nanosheet is evenly distributed on the surface of ZIF-67 and ZIF-67 is coated to form shell-core structure, MoS2 Nanosheet is 1T phase and 2H phase.The application also discloses the preparation method of the above-mentioned MoS2 / ZIF-67 core-shell material and its application in electrocatalysis, surface enhanced Raman spectroscopy detection.The application also discloses an electrode, the film is attached to the surface of electrode, and the film contains the above-mentioned MoS2 / ZIF-67 core-shell material.The application also discloses a kind of electrocatalytic hydrogen production method and a kind of method for enhancing SERS detection sensitivity.The MoS2 / ZIF-67 core-shell material described in the application has larger specific surface area and reactive site, and has excellent electrocatalytic and SERS performance.

Description

Technical Field

[0001] This invention relates to the field of catalyst technology, and in particular to a MoS2 / ZIF-67 core-shell material, its preparation method, and its applications. Background Technology

[0002] A healthy ecological environment is the foundation for human health, survival, and development. While preparing clean energy sources to alleviate the global energy crisis is important, prioritizing human health is equally crucial. The integration of heterostructured materials is a pillar of modern materials research, enabling the application of semiconductor materials in catalysis, energy storage, and sensing. Interfaces between different materials can generate novel functions, which are also vital in practical applications. However, designing low-cost, highly stable, convenient, and efficient multifunctional heterostructured materials remains a significant challenge.

[0003] MoS2 has attracted widespread attention due to its abundant reserves, excellent electrocatalytic performance, and high chemical stability. However, because the active sites of MoS2 are often only located at the edges, its catalytic hydrogen evolution activity and surface-enhanced Raman spectroscopy (SERS) properties are limited. Unlike the semiconductor-like 2H-MoS2, 1T-phase MoS2 exhibits metallic properties, with electronic conductivity approximately 10 times higher than that of 2H-MoS2. 5 However, the thermal instability of 1T-MoS2 makes it difficult to synthesize directly, and it is unstable under natural conditions, which greatly limits its applications. Summary of the Invention

[0004] Based on the technical problems existing in the background technology, this invention proposes a MoS2 / ZIF-67 core-shell material, its preparation method, and its applications. The MoS2 / ZIF-67 core-shell material of this invention has a large specific surface area and reactive active sites, and has dual functions. It not only exhibits extremely high stability and electrocatalytic hydrogen production activity in alkaline electrolytes, but also enables efficient SERS detection of various dyes in actual water bodies and SERS detection of low concentrations of bilirubin in serum, thus broadening the application range of this type of material. This invention not only solves the problem of resource scarcity in the energy field, but also addresses the health issues of the human living environment. Moreover, its performance in these aspects far exceeds that of most reported semiconductor materials, and it has excellent application prospects.

[0005] This invention proposes a MoS2 / ZIF-67 core-shell material. The MoS2 / ZIF-67 core-shell material is cubic in shape. MoS2 nanosheets are uniformly distributed on the surface of ZIF-67 and encapsulate ZIF-67 to form a core-shell structure. The MoS2 nanosheets are in the form of 1T phase and 2H phase.

[0006] Preferably, the thickness of the MoS2 nanosheets is 10-20 nm.

[0007] Preferably, the side length of the MoS2 / ZIF-67 core-shell material cube is 3.5-4.5 μm.

[0008] This invention proposes a method for preparing the above-mentioned MoS2 / ZIF-67 core-shell material, comprising the following steps: mixing an aqueous solution containing a molybdenum source and a sulfur source with ZIF-67, and carrying out a hydrothermal reaction to obtain the MoS2 / ZIF-67 core-shell material.

[0009] Preferably, the hydrothermal reaction temperature is 220-240℃ and the time is 18-20h.

[0010] Preferably, the molybdenum source is at least one of molybdate, molybdate hydrate, or phosphomolybdic acid. More preferably, the molybdenum source is ammonium molybdate or ammonium molybdate tetrahydrate.

[0011] Preferably, the sulfur source is at least one of thiourea, thioacetamide, and sodium thioacetate.

[0012] Preferably, the molar ratio of molybdenum in the molybdenum source to sulfur in the sulfur source is 1:32-36.

[0013] Preferably, the ratio of molybdenum source to ZIF-67 is 1 mmol: 0.18-0.31 g.

[0014] Preferably, after the hydrothermal reaction, solid-liquid separation, washing, and drying are performed to obtain the MoS2 / ZIF-67 core-shell material.

[0015] Preferably, the drying temperature is 50-60℃.

[0016] The aforementioned ZIF-67 is a metal-organic framework material with a zeolite imidazole ester framework structure.

[0017] Preferably, in the preparation of ZIF-67, 2-methylimidazole aqueous solution, cobalt source aqueous solution, and surfactant aqueous solution are mixed and reacted at room temperature for 12-16 hours to obtain ZIF-67.

[0018] Preferably, in the preparation process of ZIF-67, the cobalt source is at least one of cobalt nitrate, cobalt nitrate hexahydrate, cobalt sulfate, and cobalt chloride.

[0019] Preferably, in the preparation of ZIF-67, the surfactant is at least one of hexadecyltrimethylammonium bromide and sodium hexadecylbenzenesulfonate.

[0020] Preferably, in the preparation process of ZIF-67, the molar ratio of 2-methylimidazole to cobalt in the cobalt source is 100:1.5-1.7.

[0021] Preferably, in the preparation of ZIF-67, the molar ratio of 2-methylimidazole to surfactant is 100:1.2-1.4.

[0022] This invention also proposes the application of the above-mentioned MoS2 / ZIF-67 core-shell material in electrocatalysis and surface-enhanced Raman spectroscopy detection.

[0023] Preferably, its application is in electrocatalytic hydrogen evolution, surface-enhanced Raman spectroscopy for the detection of dyes and bilirubin.

[0024] The dyes mentioned above can be crystal violet (CV), methylene blue (MB), malachite green (MG), rhodamine 6G (R6G), etc.

[0025] The present invention also proposes an electrode having a thin film attached to its surface, the thin film containing the aforementioned MoS2 / ZIF-67 core-shell material.

[0026] The aforementioned film can be made from a polymer, such as a perfluorosulfonic acid polymer.

[0027] The present invention also proposes a method for electrocatalytic hydrogen production, comprising the following steps: using the above-mentioned electrode as a cathode, electrolyzing an alkaline electrolyte, and collecting hydrogen gas.

[0028] Preferably, the electrolyte in the alkaline electrolyte is an inorganic alkali.

[0029] The aforementioned inorganic base can be potassium hydroxide, sodium hydroxide, etc.; preferably, the alkaline electrolyte is a 1 mol / L potassium hydroxide aqueous solution.

[0030] The present invention also proposes a method to enhance the sensitivity of SERS detection, comprising the following steps: adding the above-mentioned MoS2 / ZIF-67 core-shell material to the test solution, and then performing SERS detection.

[0031] Beneficial effects:

[0032] 1. The MoS2 / ZIF-67 core-shell material of this invention can achieve effective core-shell composite structure, and the vertical and uniform distribution of MoS2 nanosheets on ZIF-67 avoids its tendency to aggregate. Its morphology and structure have a large specific surface area and reactive active sites. Moreover, the composite MoS2 nanosheets are a mixed phase of 1T and 2H, which solves the shortcomings of insufficient active sites and poor conductivity of MoS2 due to its inert basal plane. This invention exhibits excellent electrocatalytic and SERS performance (it can detect a variety of dyes and bilirubin in blood) and good stability (4 months). The MoS2 / ZIF-67 core-shell material has dual functions, which broadens its application in energy, environment and biology.

[0033] 2. The raw materials used in this invention are inexpensive and readily available, and there is no need to use other toxic and harmful organic surfactants and additives, making it safe and environmentally friendly; moreover, the preparation method involved is simple and the reaction conditions are mild, which is in line with the preparation concept of green synthesis.

[0034] 3. The MoS2 / ZIF-67 core-shell material described in this invention can achieve efficient hydrogen production in an alkaline electrolyte at 10 mA / cm². 2 The lowest hydrogen evolution reaction overpotential is 89mV. The MoS2 / ZIF-67 core-shell material has good conductivity and extremely high stability in alkaline electrolyte. This invention solves the shortcomings of insufficient active sites and poor conductivity of MoS2 due to its inert basal plane, broadens the application range of MoS2 / ZIF-67 core-shell material, and provides an effective way to produce hydrogen by electrolysis of water and thus alleviate the energy crisis.

[0035] 4. The MoS2 / ZIF-67 core-shell material described in this invention exhibits significant SERS enhancement effects and low detection limits for four dyes (MB, MG, R6G, and CV), respectively. Specifically, the enhancement factor of the MoS2 / ZIF-67 core-shell material for R6G can reach 6.68 × 10⁻⁶. 6 Detection limit as low as 10 -11 With a mol / L concentration, high sensitivity, and a simple and rapid detection method, it solves the problems of complex pretreatment steps and inconvenient instrument operation in traditional detection methods.

[0036] 5. The MoS2 / ZIF-67 core-shell material described in this invention can detect low concentrations of free bilirubin in serum, effectively improving the sensitivity of SERS, with a detection limit as low as 10. -10 mol / L, and at 10 -3 ~10 -10 It exhibits good linearity within the mol / L range; the detection method is rapid, overcoming the shortcomings of traditional detection methods, such as cumbersome pretreatment steps and poor stability. Attached Figure Description

[0037] Figure 1 The images show SEM images of MoS2 / ZIF-67 core-shell material and ZIF-67 material, where a represents MoS2 / ZIF-67 core-shell material and b represents ZIF-67 material.

[0038] Figure 2 The XRD patterns, Raman intrinsic spectra, and Fourier transform infrared spectra of MoS2 / ZIF-67 core-shell material, MoS2, and ZIF-67 are shown, where a is the XRD pattern, b is the Raman intrinsic spectra, and c is the Fourier transform infrared spectra.

[0039] Figure 3The graph shows the electrocatalytic hydrogen evolution performance of the electrode prepared in Example 4, where a is the LSV curve, b is the corresponding Tafel plot of a, c is the EIS spectrum, d is the electrochemical double-layer capacitance value, e is the LSV curve after 20 h, and f is the change in current density over 20 h.

[0040] Figure 4 The figures show the SERS detection results of Rhodamine 6G using MoS2 / ZIF-67 core-shell material. Figure a shows the influence of MoS2, ZIF-67, and MoS2 / ZIF-67 core-shell material on the SERS detection of Rhodamine 6G; figure b shows the SERS detection results of different concentrations of Rhodamine 6G using MoS2 / ZIF-67 core-shell material as a substrate; figure c shows the linear relationship corresponding to figure b; figure d shows the uniformity of SERS detection of Rhodamine 6G using MoS2 / ZIF-67 core-shell material; figure e shows the SERS detection results of Rhodamine 6G after four cycles of using MoS2 / ZIF-67 core-shell material; and figure f shows the SERS detection results of Rhodamine 6G after 1, 2, 3, and 4 months of storage using MoS2 / ZIF-67 core-shell material.

[0041] Figure 5 The figures show the SERS detection results of the MoS2 / ZIF-67 core-shell material for methylene blue. Figure a shows the influence of MoS2, ZIF-67, and MoS2 / ZIF-67 core-shell materials on the SERS detection of methylene blue; figure b shows the SERS detection results of different concentrations of methylene blue using the MoS2 / ZIF-67 core-shell material as a substrate; figure c shows the linear relationship corresponding to figure b; figure d shows the uniformity of the SERS detection of methylene blue using the MoS2 / ZIF-67 core-shell material; figure e shows the SERS detection results of methylene blue after four cycles of using the MoS2 / ZIF-67 core-shell material; and figure f shows the SERS detection results of methylene blue using the MoS2 / ZIF-67 core-shell material after 1, 2, 3, and 4 months of storage.

[0042] Figure 6 The figures show the SERS results of MoS2 / ZIF-67 core-shell material for crystal violet. Figure a shows the influence of MoS2, ZIF-67, and MoS2 / ZIF-67 core-shell material on the SERS detection of crystal violet; figure b shows the SERS detection of different concentrations of crystal violet using MoS2 / ZIF-67 core-shell material as a substrate; figure c shows the linear relationship corresponding to figure b; figure d shows the uniformity of the SERS detection of crystal violet using MoS2 / ZIF-67 core-shell material; figure e shows the SERS detection results of crystal violet after four cycles of using MoS2 / ZIF-67 core-shell material; and figure f shows the SERS detection results of crystal violet using MoS2 / ZIF-67 core-shell material after 1, 2, 3, and 4 months of storage.

[0043] Figure 7 The figures show the SERS results of MoS2 / ZIF-67 core-shell material on malachite green. Figure a shows the influence of MoS2, ZIF-67, and MoS2 / ZIF-67 core-shell material on the SERS results of malachite green; figure b shows the SERS results of MoS2 / ZIF-67 core-shell material as a substrate for different concentrations of malachite green; figure c shows the linear relationship corresponding to figure b; figure d shows the uniformity of SERS results of MoS2 / ZIF-67 core-shell material on malachite green; figure e shows the SERS results of MoS2 / ZIF-67 core-shell material after four cycles of use; and figure f shows the SERS results of MoS2 / ZIF-67 core-shell material on malachite green after 1, 2, 3, and 4 months of storage.

[0044] Figure 8 The SERS spectrum of MoS2 / ZIF-67 core-shell material and MoS2 for bilirubin detection, with a peak position at 1612 cm⁻¹. -1 Linear relationship plots, where a and c are SERS plots of MoS2 / ZIF-67 core-shell material and MoS2 for the detection of different concentrations of bilirubin in serum, respectively; b and d are SERS plots of MoS2 / ZIF-67 core-shell material and MoS2 at the peak position of 1612 cm⁻¹, respectively. -1 Linear relationship graph at the location. Detailed Implementation

[0045] The technical solution of the present invention will now be described in detail through specific embodiments.

[0046] Raw material information:

[0047] Ammonium molybdate tetrahydrate, purchased from Shanghai Maclean Biochemical Technology Co., Ltd., analytical grade;

[0048] Thiourea, purchased from Shanghai Maclean Biochemical Technology Co., Ltd., analytical grade;

[0049] Cobalt nitrate hexahydrate, purchased from Shenyang Guoyao Group Chemical Reagent Co., Ltd., ≥99% concentration;

[0050] 2-Methylimidazole, purchased from Shenyang Guoyao Group Chemical Reagent Co., Ltd., ≥98% concentration;

[0051] Anhydrous ethanol, purchased from Shenyang Guoyao Group Chemical Reagent Co., Ltd., analytical grade;

[0052] Hexadecyltrimethylamine bromide, purchased from Shenyang Guoyao Group Chemical Reagent Co., Ltd., ≥99% concentration;

[0053] Isopropanol, purchased from Shanghai Maclean Biochemical Technology Co., Ltd., analytical grade;

[0054] The perfluorosulfonic acid polymer solution (Nafion) was purchased from Beijing Cool Chemical Technology Co., Ltd., with a concentration of 5%.

[0055] Potassium hydroxide, purchased from Shanghai Maclean Biochemical Technology Co., Ltd., analytical grade;

[0056] Crystal violet, purchased from Shanghai Maclean Biochemical Technology Co., Ltd., ≥98% concentration;

[0057] Methylene blue, purchased from Shanghai Maclean Biochemical Technology Co., Ltd., concentration ≥70%;

[0058] Malachite green, purchased from Shanghai Maclean Biochemical Technology Co., Ltd., ≥95% concentration;

[0059] Rhodamine B, purchased from Shanghai Maclean Biotechnology Co., Ltd., analytical grade.

[0060] Example 1

[0061] A method for preparing a MoS2 / ZIF-67 core-shell material includes the following steps:

[0062] 9 g (109 mmol) of 2-methylimidazole was added to 200 mL of deionized water and stirred vigorously for 2 min to obtain an aqueous solution of 2-methylimidazole; 0.5 g (1.7 mmol) of cobalt nitrate hexahydrate was added to 10 mL of deionized water and stirred for 2 min to obtain an aqueous solution of cobalt source; 0.5 g (1.4 mmol) of hexadecyltrimethylammonium bromide was added to 10 mL of deionized water to dissolve to obtain an aqueous solution of surfactant; the aqueous solutions of 2-methylimidazole, cobalt source, and surfactant were mixed and stirred at 800 rpm at room temperature for 12 h, the precipitate was collected by centrifugation, the precipitate was washed three times with ethanol, and dried under vacuum to obtain ZIF-67;

[0063] 1.2358 g (1 mmol) of ammonium molybdate tetrahydrate and 2.7403 g (36 mmol) of thiourea were added to 60 mL of deionized water and stirred with a magnetic stirrer for 30-40 min until completely dissolved. Then, 0.2 g of ZIF-67 was added and stirred until well mixed. The mixture was then transferred to a 100 mL Teflon-lined stainless steel autoclave and placed in a drying oven at 220 °C for hydrothermal reaction for 18 h. The black precipitate was collected by centrifugation and washed three times with deionized water and alcohol, respectively. The precipitate was then dried in a drying oven at 60 °C for 12 h to obtain a black solid powder, which is the MoS2 / ZIF-67 core-shell material.

[0064] The MoS2 / ZIF-67 core-shell material prepared in Example 1 was tested, and the results are as follows: Figure 1-2 As shown.

[0065] Figure 1The images show SEM images of MoS2 / ZIF-67 core-shell material and ZIF-67 material, where a represents MoS2 / ZIF-67 core-shell material and b represents ZIF-67 material.

[0066] Depend on Figure 1 It can be seen that the ZIF-67 material is cubic in shape, and the MoS2 nanosheets grow uniformly and densely on the surface of ZIF-67, encapsulating ZIF-67 to form a core-shell structure. The MoS2 nanosheets are in contact with each surface of ZIF-67 at a certain angle, and can be upright or obliquely inserted. The MoS2 / ZIF-67 core-shell material is cubic with a side length of 4μm. The thickness of the MoS2 nanosheets is 10-20nm, and the side length of the ZIF-67 material is 3μm.

[0067] Figure 2 The XRD patterns, Raman intrinsic spectra, and Fourier transform infrared spectra of MoS2 / ZIF-67 core-shell material, MoS2, and ZIF-67 are shown, where a is the XRD pattern, b is the Raman intrinsic spectra, and c is the Fourier transform infrared spectra.

[0068] Depend on Figure 2 It can be seen that: Figure 2 (a) The MoS2 / ZIF-67 core-shell material in the middle has characteristic peaks of both MoS2 and ZIF-67; Figure 2 (b) The MoS2 / ZIF-67 core-shell material has peaks of two material vibration modes at the same time, and after recombination, in addition to the characteristic peak of the 2H phase, a metallic 1T phase is also generated. Figure 2 (c) The MoS2 / ZIF-67 core-shell material exhibits both the Mo-S bond and the vibrational peak of 2-methylimidazole unique to ZIF-67, indicating that the two materials were successfully composited.

[0069] Example 2

[0070] A method for preparing a MoS2 / ZIF-67 core-shell material includes the following steps:

[0071] 9.1 g (111 mmol) of 2-methylimidazole was added to 200 mL of deionized water and stirred vigorously for 2 min to obtain an aqueous solution of 2-methylimidazole; 0.5 g (1.7 mmol) of cobalt nitrate hexahydrate was added to 10 mL of deionized water and stirred for 2 min to obtain an aqueous solution of cobalt source; 0.5 g (1.4 mmol) of hexadecyltrimethylammonium bromide was added to 10 mL of deionized water to dissolve to obtain an aqueous solution of surfactant; the aqueous solutions of 2-methylimidazole, cobalt source, and surfactant were mixed and stirred at 800 rpm at room temperature for 15 h, the precipitate was collected by centrifugation, the precipitate was washed three times with ethanol, and dried under vacuum to obtain ZIF-67;

[0072] 1.23 g (1 mmol) of ammonium molybdate tetrahydrate and 2.51 g (33 mmol) of thiourea were added to 60 mL of deionized water and stirred with a magnetic stirrer for 30-40 min until completely dissolved. Then, 0.2 g of ZIF-67 was added and stirred until well mixed. The mixture was then transferred to a 100 mL Teflon-lined stainless steel autoclave and placed in a drying oven at 220 °C for hydrothermal reaction for 20 h. The black precipitate was collected by centrifugation and washed three times with deionized water and alcohol, respectively. The precipitate was then dried in a drying oven at 50 °C for 8 h to obtain a black solid powder, which is the MoS2 / ZIF-67 core-shell material.

[0073] Example 3

[0074] A method for preparing a MoS2 / ZIF-67 core-shell material includes the following steps:

[0075] 9 g (109 mmol) of 2-methylimidazole was added to 200 mL of deionized water and stirred vigorously for 2 min to obtain an aqueous solution of 2-methylimidazole; 0.55 g (1.9 mmol) of cobalt nitrate hexahydrate was added to 10 mL of deionized water and stirred for 2 min to obtain an aqueous solution of cobalt source; 0.55 g (1.5 mmol) of hexadecyltrimethylammonium bromide was added to 10 mL of deionized water to dissolve to obtain an aqueous solution of surfactant; the aqueous solutions of 2-methylimidazole, cobalt source, and surfactant were mixed and stirred at 800 rpm at room temperature for 13 h, the precipitate was collected by centrifugation, the precipitate was washed three times with ethanol, and dried under vacuum to obtain ZIF-67;

[0076] 1.24 g (1 mmol) of ammonium molybdate tetrahydrate and 2.52 g (33 mmol) of thiourea were added to 60 mL of deionized water and stirred with a magnetic stirrer for 30-40 min until completely dissolved. Then, 0.2 g of ZIF-67 was added and stirred until well mixed. The mixture was then transferred to a 100 mL Teflon-lined stainless steel autoclave and placed in a drying oven at 240 °C for hydrothermal reaction for 18 h. The black precipitate was collected by centrifugation and washed three times with deionized water and alcohol, respectively. The precipitate was then dried in a drying oven at 60 °C for 6 h to obtain a black solid powder, which is the MoS2 / ZIF-67 core-shell material.

[0077] Example 4

[0078] An electrode preparation method includes the following steps: 2 mg of the MoS2 / ZIF-67 core-shell material obtained in Example 1 is added to a 0.5% Nafion solution (solvent is isopropanol), and the solution is ultrasonically dispersed in an ultrasonic machine to obtain a dispersion. 2 μL of the dispersion is then dropped onto a glassy carbon electrode with a diameter of 3 mm using a pipette. The electrode is then naturally dried at room temperature for 10 min to obtain the electrode. A perfluorosulfonic acid polymer film containing the MoS2 / ZIF-67 core-shell material is attached to the electrode surface.

[0079] A standard three-electrode system was constructed using the aforementioned electrode as the cathode (i.e., working electrode), a carbon rod as the anode (i.e., counter electrode), and an Hg / HgO electrode as the reference electrode. A 1 mol / L potassium hydroxide aqueous solution was used as the electrolyte, and the electrolyte was purged with nitrogen for 0.5 h to remove dissolved oxygen. Several cyclic voltammetry tests were performed between -0.19 and -0.29 V to remove organic matter and other impurities from the cathode surface, converting all potentials to the potential relative to the reversible hydrogen electrode. Electrocatalytic hydrogen evolution performance was tested and compared with electrodes prepared using MoS2 and ZIF-67 as cathodes. The results are as follows: Figure 3 As shown.

[0080] Figure 3 The graph shows the electrocatalytic hydrogen evolution performance of the electrode prepared in Example 4, where a is the LSV curve, b is the corresponding Tafel plot of a, c is the EIS spectrum, d is the electrochemical double-layer capacitance value, e is the LSV curve after 20 h, and f is the change in current density over 20 h.

[0081] Figure 3 The test conditions in c are as follows: apply a potential of -0.35V to the electrode, test the electrochemical impedance spectroscopy at a frequency of 1-100000Hz, and calculate the resistance Rs of the solution from the electrochemical impedance spectroscopy image.

[0082] Depend on Figure 3 It can be seen that the MoS2 / ZIF-67 core-shell material has good electrocatalytic hydrogen evolution performance and long-term stability. Compared with MoS2 and ZIF-67, the MoS2 / ZIF-67 core-shell material not only improves the conductivity, but also increases the number of active sites required for the reaction.

[0083] Example 5

[0084] Select a concentration of 10 -3 Methylene blue (MB), rhodamine 6G (R6G), crystal violet (CV), and malachite green (MG) were used as substrates. MoS2, ZIF-67, and the MoS2 / ZIF-67 core-shell material described in Example 1 were added as substrates, respectively. The substrates were shaken for 2 hours to ensure sufficient contact between the substrates and each substrate. SERS detection was then performed to verify the optimal SERS activity of each substrate. The results are as follows: Figure 4-7 As shown.

[0085] Figure 4The figures show the SERS detection results of Rhodamine 6G using MoS2 / ZIF-67 core-shell material. Figure a shows the influence of MoS2, ZIF-67, and MoS2 / ZIF-67 core-shell material on the SERS detection of Rhodamine 6G; figure b shows the SERS detection results of different concentrations of Rhodamine 6G using MoS2 / ZIF-67 core-shell material as a substrate; figure c shows the linear relationship corresponding to figure b; figure d shows the uniformity of SERS detection of Rhodamine 6G using MoS2 / ZIF-67 core-shell material; figure e shows the SERS detection results of Rhodamine 6G after four cycles of using MoS2 / ZIF-67 core-shell material; and figure f shows the SERS detection results of Rhodamine 6G after 1, 2, 3, and 4 months of storage using MoS2 / ZIF-67 core-shell material.

[0086] Figure 5 The figures show the SERS detection results of the MoS2 / ZIF-67 core-shell material for methylene blue. Figure a shows the influence of MoS2, ZIF-67, and MoS2 / ZIF-67 core-shell materials on the SERS detection of methylene blue; figure b shows the SERS detection results of different concentrations of methylene blue using the MoS2 / ZIF-67 core-shell material as a substrate; figure c shows the linear relationship corresponding to figure b; figure d shows the uniformity of the SERS detection of methylene blue using the MoS2 / ZIF-67 core-shell material; figure e shows the SERS detection results of methylene blue after four cycles of using the MoS2 / ZIF-67 core-shell material; and figure f shows the SERS detection results of methylene blue using the MoS2 / ZIF-67 core-shell material after 1, 2, 3, and 4 months of storage.

[0087] Figure 6 The figures show the SERS results of MoS2 / ZIF-67 core-shell material for crystal violet. Figure a shows the influence of MoS2, ZIF-67, and MoS2 / ZIF-67 core-shell material on the SERS detection of crystal violet; figure b shows the SERS detection of different concentrations of crystal violet using MoS2 / ZIF-67 core-shell material as a substrate; figure c shows the linear relationship corresponding to figure b; figure d shows the uniformity of the SERS detection of crystal violet using MoS2 / ZIF-67 core-shell material; figure e shows the SERS detection results of crystal violet after four cycles of using MoS2 / ZIF-67 core-shell material; and figure f shows the SERS detection results of crystal violet using MoS2 / ZIF-67 core-shell material after 1, 2, 3, and 4 months of storage.

[0088] Figure 7The figures show the SERS results of MoS2 / ZIF-67 core-shell material on malachite green. Figure a shows the influence of MoS2, ZIF-67, and MoS2 / ZIF-67 core-shell material on the SERS results of malachite green; figure b shows the SERS results of MoS2 / ZIF-67 core-shell material as a substrate for different concentrations of malachite green; figure c shows the linear relationship corresponding to figure b; figure d shows the uniformity of SERS results of MoS2 / ZIF-67 core-shell material on malachite green; figure e shows the SERS results of MoS2 / ZIF-67 core-shell material after four cycles of use; and figure f shows the SERS results of MoS2 / ZIF-67 core-shell material on malachite green after 1, 2, 3, and 4 months of storage.

[0089] Depend on Figure 4-7 (a) It can be seen that the MoS2 / ZIF-67 core-shell material can improve the SERS detection sensitivity of methylene blue, rhodamine 6G, crystal violet, and malachite green, with an enhancement factor of 6.68 × 10 for rhodamine 6G. 6 Furthermore, the MoS2 / ZIF-67 core-shell material significantly improves the sensitivity of SERS detection compared to MoS2 and ZIF-67.

[0090] Depend on Figure 4-7 (bc) It can be seen that the addition of MoS2 / ZIF-67 core-shell material can make the four dyes exhibit a linear relationship in the low concentration range (the peak positions of Rhodamine 6G, Methylene Blue, Crystal Violet, and Malachite Green are 1651 cm⁻¹, respectively). -1 1626cm -1 1622cm -1 1618cm -1 The detection limits for the four dyes are very low, with Rhodamine 6G having a detection limit as low as 10. - 11 mol / L.

[0091] Depend on Figure 4-7 (df) shows that the MoS2 / ZIF-67 core-shell material has good cycling performance, stability and uniformity.

[0092] The MoS2 / ZIF-67 core-shell material described in this invention not only has extremely high SERS detection performance for a variety of dyes, but also has good versatility.

[0093] Example 6

[0094] MoS2 / ZIF-67 core-shell material for low-concentration SERS detection of bilirubin in serum.

[0095] The specific steps are as follows:

[0096] Bovine serum was added to PBS buffer and shaken for 15 minutes. Then, different amounts of bilirubin were added, and the mixture was sonicated for 2 hours to obtain a bilirubin concentration of 10. -3 -10 -11 A solution of mol / L;

[0097] Take 1 mL of bilirubin solutions of different concentrations, add 0.01 g of the MoS2 / ZIF-67 core-shell material described in Example 1, and shake well at 37°C for 2 h to obtain the analytes, which are then analyzed by SERS. The results are compared with those of MoS2; the results are as follows. Figure 8 As shown.

[0098] Figure 8 The SERS spectrum of MoS2 / ZIF-67 core-shell material and MoS2 for bilirubin detection, with a peak position at 1612 cm⁻¹. -1 Linear relationship plots, where a and c are SERS plots of MoS2 / ZIF-67 core-shell material and MoS2 for the detection of different concentrations of bilirubin in serum, respectively; b and d are SERS plots of MoS2 / ZIF-67 core-shell material and MoS2 at the peak position of 1612 cm⁻¹, respectively. -1 Linear relationship graph at the location.

[0099] Depend on Figure 8 It can be seen that the detection limit of MoS2 / ZIF-67 core-shell material for bilirubin can be as low as 10. -10 mol / L, at 1612 cm -1 The peak intensity shows a linear relationship, R 2 The limit of detection can reach 0.98, which is far superior to that of pure MoS2 for bilirubin detection (the lowest detection limit is only 10). -5 (mol / L). This result demonstrates that the MoS2 / ZIF-67 core-shell material can be used for the detection of low concentrations of bilirubin.

[0100] In summary, the MoS2 / ZIF-67 core-shell material described in this invention can be used for electrocatalytic hydrogen evolution under alkaline conditions, and can also achieve highly sensitive SERS detection of various dyes and highly sensitive SERS detection of bilirubin in serum in actual water bodies. As a multifunctional material, the MoS2 / ZIF-67 core-shell material has promising applications in both energy and detection fields.

[0101] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the technology disclosed in the present invention, based on the technical solution and inventive concept of the present invention, should be covered within the scope of protection of the present invention.

Claims

1. A MoS2 / ZIF-67 core-shell material, characterized in that, The MoS2 / ZIF-67 core-shell material is cubic in shape. MoS2 nanosheets are uniformly distributed on the surface of ZIF-67 and encapsulate ZIF-67 to form a core-shell structure. The MoS2 nanosheets are in 1T phase and 2H phase. The preparation method of the MoS2 / ZIF-67 core-shell material includes the following steps: mixing an aqueous solution containing a molybdenum source and a sulfur source with ZIF-67, and carrying out a hydrothermal reaction to obtain the MoS2 / ZIF-67 core-shell material. The ratio of molybdenum source to ZIF-67 was 1 mmol: 0.18-0.31 g; In the preparation of ZIF-67, 2-methylimidazole aqueous solution, cobalt source aqueous solution, and surfactant aqueous solution are mixed and reacted at room temperature for 12-16 hours to obtain ZIF-67.

2. The MoS2 / ZIF-67 core-shell material according to claim 1, characterized in that, The thickness of MoS2 nanosheets is 10-20 nm.

3. The MoS2 / ZIF-67 core-shell material according to claim 1 or 2, characterized in that, The side length of the MoS2 / ZIF-67 core-shell material cube is 3.5-4.5 μm.

4. A method for preparing the MoS2 / ZIF-67 core-shell material as described in any one of claims 1-3, characterized in that, The process includes the following steps: mixing an aqueous solution containing a molybdenum source and a sulfur source with ZIF-67 and carrying out a hydrothermal reaction to obtain a MoS2 / ZIF-67 core-shell material; The ratio of molybdenum source to ZIF-67 was 1 mmol: 0.18-0.31 g; In the preparation of ZIF-67, 2-methylimidazole aqueous solution, cobalt source aqueous solution, and surfactant aqueous solution are mixed and reacted at room temperature for 12-16 hours to obtain ZIF-67.

5. The method for preparing the MoS2 / ZIF-67 core-shell material according to claim 4, characterized in that, The hydrothermal reaction is carried out at a temperature of 220-240℃ for 18-20 hours.

6. The method for preparing the MoS2 / ZIF-67 core-shell material according to claim 4 or 5, characterized in that, The molybdenum source is at least one of molybdate or phosphomolybdic acid.

7. The method for preparing the MoS2 / ZIF-67 core-shell material according to claim 4 or 5, characterized in that, The sulfur source is at least one of thiourea, thioacetamide, and sodium thioacetate.

8. The method for preparing the MoS2 / ZIF-67 core-shell material according to claim 4 or 5, characterized in that, The molar ratio of molybdenum in the molybdenum source to sulfur in the sulfur source is 1:32-36.

9. The method for preparing the MoS2 / ZIF-67 core-shell material according to claim 4 or 5, characterized in that, After hydrothermal reaction, solid-liquid separation, washing, and drying were performed to obtain MoS2 / ZIF-67 core-shell material.

10. The method for preparing the MoS2 / ZIF-67 core-shell material according to claim 4 or 5, characterized in that, The drying temperature is 50-60℃.

11. The method for preparing the MoS2 / ZIF-67 core-shell material according to claim 4 or 5, characterized in that, In the preparation of ZIF-67, the cobalt source is at least one of cobalt nitrate, cobalt sulfate, and cobalt chloride.

12. The method for preparing the MoS2 / ZIF-67 core-shell material according to claim 4 or 5, characterized in that, In the preparation of ZIF-67, the surfactant is at least one of hexadecyltrimethylammonium bromide and sodium hexadecylbenzenesulfonate.

13. The method for preparing the MoS2 / ZIF-67 core-shell material according to claim 4 or 5, characterized in that, In the preparation of ZIF-67, the molar ratio of 2-methylimidazole to cobalt in the cobalt source is 100:1.5-1.

7.

14. The method for preparing the MoS2 / ZIF-67 core-shell material according to claim 4 or 5, characterized in that, In the preparation of ZIF-67, the molar ratio of 2-methylimidazole to surfactant is 100:1.2-1.

4.

15. The application of the MoS2 / ZIF-67 core-shell material as described in any one of claims 1-3 in electrocatalytic hydrogen evolution, surface-enhanced Raman spectroscopy detection of dyes and bilirubin.

16. An electrode, characterized in that, A thin film is attached to the electrode surface, and the thin film contains the MoS2 / ZIF-67 core-shell material as described in any one of claims 1-3.

17. A method for electrocatalytic hydrogen production, characterized in that, The process includes the following steps: using the electrode described in claim 16 as the cathode, electrolyzing the alkaline electrolyte, and collecting hydrogen gas.

18. The method for electrocatalytic hydrogen production according to claim 17, characterized in that, The electrolyte in an alkaline electrolyte solution is an inorganic base.

19. A method for enhancing the detection sensitivity of SERS, characterized in that, The procedure includes the following steps: adding the MoS2 / ZIF-67 core-shell material according to any one of claims 1-3 to the test solution, and then performing SERS detection.

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