Preparation method of D-MoS2atrGO-Ti3C2Tx nano composite material and preparation method of heavy metal ion sensor

Abstract

The invention belongs to the technical field of electrochemical sensors, and particularly discloses a preparation method of a D-MoS2 (at) rGO-Ti3C2Tx nano composite material, a preparation method of a heavy metal ion sensor, and a preparation method of the heavy metal ion sensor based on the D-MoS2 (at) rGO-Ti3C2Tx nano composite material. Comprising the following steps: coating the surface of a pretreated glassy carbon electrode with a solution of a D-MoS2 (at) rGO-Ti3C2Tx nano composite material, and drying to obtain the heavy metal ion sensor, the heavy metal ion sensor based on the D-MoS2 (at) rGO-Ti3C2Tx nanocomposite prepared by the invention can be used for rapidly and sensitively detecting trace heavy metal ions in a tap water system.

Description

Technical Field

[0001] The present invention belongs to the technical field of electrochemical sensors, and specifically relates to D-MoS2@rGO-Ti3C2T x Preparation method of nanocomposite material, preparation method of heavy metal ion sensor. Background Art

[0002] Water is the world's most important natural resource. It is not only the foundation of life but also an important pillar of human civilization. However, human activities have led to the release of many toxic and hazardous chemicals into water bodies, causing serious environmental problems. Among them, heavy metal ion pollution is the most serious source of pollution. Due to the characteristics of heavy metals in the environment, such as high stability, wide distribution, difficulty in biodegradation, and high toxicity, they can easily cause irreversible damage to the surrounding environment. Therefore, the development of sensitive and rapid methods for the detection of heavy metal ions is very necessary and important. Compared with traditional spectroscopy, mass spectrometry, and chromatography, electrochemical detection methods (anodic stripping voltammetry) are recognized as one of the most effective methods for the detection of trace heavy metal ions due to their advantages such as high sensitivity, low detection limit, low cost, and fast analysis speed. In addition, they are portable instruments that can achieve real-time in situ detection. Therefore, they have been highly developed in environmental science.

[0003] Electrode modification materials play an important role in electrochemical sensors. With the development of nanotechnology, the advantages of nanomaterials in the field of sensor electrodes are becoming more and more significant. Nanomaterials can not only effectively improve the conductivity and catalytic performance of sensors, but also achieve rapid enrichment of heavy metal ions on the surface of modified electrodes. They are ideal sensor materials.

[0004] Molybdenum disulfide (MoS2) is a layered transition metal disulfide with an S-Mo-S sandwich structure typically formed by van der Waals interactions. This structure provides sufficient space for the adsorption of heavy metal ions, thereby enhancing the adsorption capacity and large specific surface area; however, pure MoS2 has poor dispersibility in aqueous solution, is easy to stack, and has relatively poor electrical properties, which will hinder ion transport, reduce the utilization of active sites, and thus reduce the detection performance of heavy metal ions in aqueous systems.

[0005] Therefore, it is urgent to prepare a D-MoS2@rGO-Ti3C2T x Nanocomposites and coatings D-MoS2@rGO-Ti3C2T x Nanocomposite heavy metal ion sensors. Summary of the Invention

[0006] The purpose of the present invention is to provide a preparation method of D-MoS2@rGO-Ti3C2Tx nanocomposite material and a preparation method of heavy metal ion sensor to realize the detection of trace heavy metal ions in water.

[0007] The technical solution adopted by the present invention is: D-MoS2@rGO-Ti3C2T x The preparation method of the nanocomposite material comprises the following steps:

[0008] S1: Graphene oxide, Ti3C2T x , ammonium molybdate tetrahydrate, and then deionized water is added and ultrasonic vibration is performed to obtain a suspension;

[0009] S2: thiourea and cetyltrimethylammonium bromide were mixed and then added into deionized water, and magnetic stirring was performed to obtain a solution;

[0010] S3: The suspension obtained in S1 was mixed with the solution obtained in S2, and then transferred to an autoclave for temperature reaction to obtain D-MoS2@rGO-Ti3C2T x Precursor fluid;

[0011] S4: D-MoS2@rGO-Ti3C2T x The precursor solution was centrifuged and the precipitate was taken. The precipitate was washed alternately with deionized water and anhydrous ethanol, and the washing was repeated 3-5 times. Then, the precipitate was vacuum dried to obtain D-MoS2@rGO-Ti3C2T x Nanocomposite materials.

[0012] Furthermore, graphene oxide, Ti3C2T x , the addition ratio of ammonium molybdate tetrahydrate is 0.01-0.03g:0.01-0.03g:0.2-0.8g.

[0013] Furthermore, the addition ratio of thiourea to hexadecyltrimethylammonium bromide in S2 is 0.2-1.0 g: 0.01-0.2 g.

[0014] Furthermore, the parameters of the ultrasonic oscillation in S1 are set as follows: the ultrasonic oscillator frequency is 20-60 KHz, and the ultrasonic treatment time is 0.5-4 h.

[0015] Furthermore, the amount of deionized water added to S1 is 10-50 mL.

[0016] Furthermore, the parameters of the magnetic stirring in S2 are set as follows: the speed of the magnetic stirrer is 200-800 rpm, and the magnetic stirring treatment time is 5-15 min.

[0017] Furthermore, the temperature-raising reaction condition in S3 is: reacting at 160-300° C. for 6-24 hours.

[0018] Furthermore, the volume ratio of the suspension to the solution in S3 is 3:2.

[0019] Another technical solution adopted by the present invention is a method for preparing a heavy metal ion sensor, comprising the following steps:

[0020] Step a: D-MoS2@rGO-Ti3C2T x The nanocomposite was added to deionized water to obtain 2 mg / mL of D-MoS2@rGO-Ti3C2T x suspension;

[0021] Step b: pre-treating the glassy carbon electrode;

[0022] Step c: Then, 6 μl of the suspension was transferred and evenly coated on the surface of the pretreated glassy carbon electrode, and dried under an infrared lamp to obtain a heavy metal ion sensor.

[0023] Furthermore, the pretreatment method of the glassy carbon electrode in step b is: polishing the glassy carbon electrode with 0.3μm and 0.05μm alumina powder in sequence until the potential difference between the oxidation peak and the reduction peak in its cyclic voltammetry curve is 60-80mV. After completion, the glassy carbon electrode is washed with deionized water and the washed electrode is placed under an infrared lamp for drying.

[0024] The beneficial effects of the present invention are:

[0025] (1) The present invention uses ammonium molybdate tetrahydrate ((NH4)6Mo7O 24 4H2O) as molybdenum source and thiourea (CH4N2S) as sulfur source, rGO and Ti3C2T x As the matrix, a defective structured D-MoS2@rGO-Ti3C2T was synthesized by a one-step solvothermal method. x Nanomaterials were modified on glassy carbon electrodes to prepare D-MoS2@rGO-Ti3C2T x / GCE sensor can significantly improve the detection sensitivity of the working electrode to heavy metal ions Pb(II) and Cd(II) in water.

[0026] (2) The sensor prepared by the present invention contains abundant sulfur groups and defect structures on its surface and edges, which can form strong bonds with heavy metals such as Hg(II) and Pb(II), effectively increasing the active sites. In addition, the S vacancies provided by the present invention can significantly promote charge transfer and improve the electrochemical performance of the material.

[0027] (3) The present invention combines MoS2 with rGO and Ti3C2T with strong electrochemical performancex Nanomaterial composite, through chemical reaction on rGO and Ti3C2T x In situ growth of MoS2 nanoflowers on the surface can avoid the undesirable agglomeration of MoS2. The larger spatial depletion layer at the interface can also promote the transmission of electrons, greatly improving the detection performance. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0029] Figure 1 CV (Cyclic Voltammogram) diagram of the pretreated GCE (glassy carbon electrode) according to an embodiment of the present invention;

[0030] Figure 2 It is D-MoS2@rGO-Ti3C2T x / GCE quantitative detection standard curve for Cd(II) (a) and its SWASV (Square Wave Anodic Stripping Voltammetry) graph (b);

[0031] Figure 3 It is D-MoS2@rGO-Ti3C2T x / GCE (Glassy Carbon Electrode) quantitative detection standard curve for Pb(II) (a) and its SWASV graph (b);

[0032] Figure 4 It is D-MoS2@rGO-Ti3C2T x / GCE quantitative detection standard curve for coexisting Cd(II) and Pb(II) (a) and its SWASV graph (b);

[0033] Figure 5 Stability and repeatability study: (a) D-MoS2@rGO-Ti3C2T x / GCE sensor was continuously tested in 0.1M ABS (Acetate Buffer) (pH = 4.5) containing 100 μg / L coexisting Cd(II) and Pb(II); (b) Continuous detection results; (c) Five D-MoS2@rGO-Ti3C2T xDetection results of the GCE sensor for 100 μg / L coexisting Cd(II) and Pb(II); (d) The effect of storage period on the results;

[0034] Figure 6 It is the result of the influence of interfering ions in common water environments;

[0035] Figure 7 SEM (Scanning Electron Microscope) images: (a) MoS2, (b) D-MoS2, (c) D-MoS2@Ti3C2T x 、(d)D-MoS2@rGO、(e)The first D-MoS2@rGO-Ti3C2T x Image, (f) the second D-MoS2@rGO-Ti3C2T x Image, (g) D-MoS2@rGO-Ti3C2T x EDS (Energy-Dispersive Spectrometer) energy spectrum analysis report and EDS (Energy-Dispersive Spectroscopy) element mapping diagram;

[0036] Figure 8 D-MoS2, D-MoS2@rGO and D-MoS2@rGO-Ti3C2T x XPS (X-ray Photoelectron Spectroscopy) full spectrum image (a), D-MoS2@rGO-Ti3C2T x High-resolution XPS spectra of Mo3d (b), S2p (c), C1s (d), Ti2p (e), and O1s (f) in the nanocomposites;

[0037] Figure 9 MoS2, D-MoS2, D-MoS2@rGO and D-MoS2@rGO-Ti3C2T xTEM (Transmission Electron Microscopy) images and their HRTEM (High-Resolution Transmission Electron Microscopy) images, (a) TEM image of MoS2, (b) HRTEM image of MoS2, (c) TEM image of D-MoS2, (d) HRTEM image of D-MoS2, (e) TEM image of D-MoS2@rGO, (f) HRTEM image of D-MoS2@rGO, (g) D-MoS2@rGO-Ti3C2T x TEM image, (h) D-MoS2@rGO-Ti3C2T x HRTEM images;

[0038] Figure 10 D-MoS2, D-MoS2@Ti3C2T x , D-MoS2@rGO and D-MoS2@rGO-Ti3C2T x XRD pattern of . DETAILED DESCRIPTION

[0039] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0040] The present invention provides D-MoS2@rGO-Ti3C2T x The preparation method of the nanocomposite material comprises the following steps:

[0041] 1.D-MoS2@rGO-Ti3C2T x Preparation method of nanocomposite material

[0042] Step S1: Preparation of suspension: 0.0001-0.03g graphene oxide, 0.0001-0.03g Ti3C2T x and 0.2-0.8g ammonium molybdate tetrahydrate (NH4)6Mo7O 24 After mixing with 4H2O, add 10-50 mL of deionized water and oscillate at an ultrasonic frequency of 20-60 kHz for 0.5-4 h to obtain a suspension.

[0043] Step S2: preparing a mixed solution, mixing 0.2-1.0 g of thiourea CH4N2S and 0.0001-0.2 g of hexadecyltrimethylammonium bromide, adding the mixture into 10-50 mL of deionized water, and magnetically stirring the mixture at a rotation speed of 200-800 rpm for 5-15 minutes to obtain a solution.

[0044] Step S3: The suspension obtained in step S1 and the solution obtained in step S2 were uniformly mixed in a ratio of 3:2 and then transferred to an autoclave for reaction at 160-300 °C for 6-24 h to obtain D-MoS2@rGO-Ti3C2T x Precursor fluid.

[0045] Step S4: centrifugation, washing and drying, D-MoS2@rGO-Ti3C2T x The precursor solution was centrifuged and the precipitate was taken. The precipitate was washed alternately with deionized water and anhydrous ethanol, and the washing was repeated 3-5 times. Then, the precipitate was vacuum dried to obtain D-MoS2@rGO-Ti3C2T x Nanocomposite materials.

[0046] 2. The present invention provides a method for preparing a heavy metal ion sensor, comprising the following steps:

[0047] Step a: 2 mg D-MoS2@rGO-Ti3C2T x The nanocomposite was added to deionized water to obtain 2 mg / mL of D-MoS2@rGO-Ti3C2T x suspension;

[0048] Step b: Pretreat the glassy carbon electrode. The pretreatment method of the glassy carbon electrode is to polish the glassy carbon electrode with 0.3μm and 0.05μm alumina powder in sequence until the potential difference between the oxidation peak and the reduction peak in its cyclic voltammetry curve is 60-80mV. After completion, wash the glassy carbon electrode with deionized water and place the cleaned electrode under an infrared lamp to dry.

[0049] Step c: Then, 6 μl of the suspension was transferred and evenly coated on the surface of the pretreated glassy carbon electrode, and dried under an infrared lamp to obtain a heavy metal ion sensor.

[0050] Example 1

[0051] D-MoS2@rGO-Ti3C2T x The preparation method of the nanocomposite material comprises the following steps:

[0052] S1. Weigh 0.015g graphene oxide, 0.02g Ti3C2T xand 0.6 g of ammonium molybdate tetrahydrate were added into 50 mL of deionized water and oscillated at an ultrasonic frequency of 60 kHz for 4 h to obtain a suspension;

[0053] S2. Weigh 0.6 g of thiourea and 0.15 g of hexadecyltrimethylammonium bromide, add them to 50 mL of deionized water, and stir magnetically at 500 rpm for 10 min to obtain a solution;

[0054] S3. The suspension obtained in step S1 and the solution obtained in step S2 were uniformly mixed in a volume ratio of 3:2 and then transferred to an autoclave and reacted at 300 ° C for 6 h to obtain D-MoS2@rGO-Ti3C2T x Precursor fluid;

[0055] S4. D-MoS2@rGO-Ti3C2T x The precursor solution was centrifuged, and the precipitate was taken and washed alternately with deionized water and anhydrous ethanol, and the washing was repeated 5 times. Then, the precipitate was vacuum dried to obtain D-MoS2@rGO-Ti3C2T x Nanocomposite materials.

[0056] The preparation method of the heavy metal ion sensor comprises the following steps:

[0057] Step a: 2 mg D-MoS2@rGO-Ti3C2T x The nanocomposite was added to deionized water to obtain 2 mg / mL of D-MoS2@rGO-Ti3C2T x suspension;

[0058] Step b: Pre-treat the glassy carbon electrode by polishing it with 0.3 μm and 0.05 μm alumina powders in sequence until the potential difference between the oxidation peak and the reduction peak in its cyclic voltammetry curve is 60-80 mV ( Figure 1 ), after completion, clean the glassy carbon electrode with deionized water and dry it under an infrared lamp;

[0059] Step c: Pipette 6 μl of the suspension and evenly coat it on the surface of the pretreated glassy carbon electrode, and dry it under an infrared lamp to obtain a heavy metal ion sensor.

[0060] Example 2

[0061] D-MoS2@rGO-Ti3C2T x The preparation method of the nanocomposite material comprises the following steps:

[0062] S1. Weigh 0.01g graphene oxide, 0.03g Ti3C2T xand 0.2 g of ammonium molybdate tetrahydrate were added into 10 mL of deionized water and oscillated at an ultrasonic frequency of 20 kHz for 0.5 h to obtain a suspension;

[0063] S2. Weigh 0.2 g of thiourea and 0.01 g of cetyltrimethylammonium bromide, add them to 10 mL of deionized water, and stir magnetically at 800 rpm for 5 min to obtain a solution;

[0064] S3. The suspension obtained in step S1 was uniformly mixed with the solution obtained in step S2 and then transferred to an autoclave and reacted at 160 ° C for 24 h to obtain D-MoS2@rGO-Ti3C2T x Precursor fluid;

[0065] S4. D-MoS2@rGO-Ti3C2T x The precursor solution was centrifuged, and the precipitate was taken and washed alternately with deionized water and anhydrous ethanol, and the washing was repeated 3 times. Then, the precipitate was vacuum dried to obtain D-MoS2@rGO-Ti3C2T x Nanocomposite materials.

[0066] The preparation method of the heavy metal ion sensor comprises the following steps:

[0067] Step a: 2 mg D-MoS2@rGO-Ti3C2T x The nanocomposite was added to deionized water to obtain 2 mg / mL of D-MoS2@rGO-Ti3C2T x suspension;

[0068] Step b: Pretreat the glassy carbon electrode by polishing it with 0.3 μm and 0.05 μm alumina powders in sequence until the potential difference between the oxidation peak and the reduction peak in its cyclic voltammetry curve is 60-80 mV. After completion, rinse the glassy carbon electrode with deionized water and dry it under an infrared lamp.

[0069] Step c: Pipette 6 μl of the suspension and evenly coat it on the surface of the pretreated glassy carbon electrode, and dry it under an infrared lamp to obtain a heavy metal ion sensor.

[0070] Example 3

[0071] D-MoS2@rGO-Ti3C2T x The preparation method of the nanocomposite material comprises the following steps:

[0072] S1. Weigh 0.03g graphene oxide, 0.01g Ti3C2T xand 0.8 g of ammonium molybdate tetrahydrate were added into 25 mL of deionized water and oscillated at an ultrasonic frequency of 40 kHz for 2 h to obtain a suspension;

[0073] S2. Weigh 1 g of thiourea and 0.2 g of hexadecyltrimethylammonium bromide, add them to 25 mL of deionized water, and stir magnetically at 200 rpm for 15 min to obtain a solution;

[0074] S3. The suspension obtained in step S1 was uniformly mixed with the solution obtained in step S2 and then transferred to an autoclave and reacted at 250 ° C for 12 h to obtain D-MoS2@rGO-Ti3C2T x Precursor fluid;

[0075] S4. D-MoS2@rGO-Ti3C2T x The precursor solution was centrifuged, and the precipitate was taken and washed alternately with deionized water and anhydrous ethanol, and the washing was repeated 4 times. Then, the precipitate was vacuum dried to obtain D-MoS2@rGO-Ti3C2T x Nanocomposite materials.

[0076] The preparation method of the heavy metal ion sensor comprises the following steps:

[0077] Step a: 2 mg D-MoS2@rGO-Ti3C2T x The nanocomposite was added to deionized water to obtain 2 mg / mL of D-MoS2@rGO-Ti3C2T x suspension;

[0078] Step b: Pretreat the glassy carbon electrode by polishing it with 0.3 μm and 0.05 μm alumina powders in sequence until the potential difference between the oxidation peak and the reduction peak in its cyclic voltammetry curve is 60-80 mV. After completion, rinse the glassy carbon electrode with deionized water and dry it under an infrared lamp.

[0079] Step c: Pipette 6 μl of the suspension and evenly coat it on the surface of the pretreated glassy carbon electrode, and dry it under an infrared lamp to obtain a heavy metal ion sensor.

[0080] Comparative Example 1

[0081] The preparation method of the MoS2 composite material comprises the following steps:

[0082] S1: Take 0.48g (NH4)6Mo7O 24 4H2O was dissolved in 30 mL of deionized water and ultrasonically vibrated at 40 kHz for 2 h to obtain a solution;

[0083] S2: Dissolve 0.46 g of CH4N2S in 20 mL of deionized water and stir magnetically at 300 rpm for 30 min to obtain a CH4N2S solution.

[0084] S3: The solution obtained in S1 was mixed with the CH4N2S solution obtained in S2, and the mixture was transferred to an autoclave and reacted at 220°C for 18 h to obtain a MoS2 precursor solution;

[0085] S4: After the MoS2 precursor solution is naturally cooled to room temperature, it is centrifuged to obtain a precipitate, and the precipitate is washed alternately with deionized water and anhydrous ethanol, and the washing is repeated three times, and then vacuum dried to obtain a MoS2 composite material.

[0086] The preparation method of the heavy metal ion sensor comprises the following steps:

[0087] Step a: 2 mg of MoS2 composite material was added to deionized water to obtain a 2 mg / mL MoS2 suspension;

[0088] Step b: Pretreat the glassy carbon electrode by polishing it with 0.3 μm and 0.05 μm alumina powders in sequence until the potential difference between the oxidation peak and the reduction peak in its cyclic voltammetry curve is 60-80 mV. After completion, rinse the glassy carbon electrode with deionized water and dry it under an infrared lamp.

[0089] Step c: Pipette 6 μl of MoS2 suspension and evenly coat it on the surface of the pretreated glassy carbon electrode, and place it under an infrared lamp to dry to obtain a heavy metal ion sensor.

[0090] Comparative Example 2

[0091] The preparation method of the D-MoS2 composite material comprises the following steps:

[0092] S1: Take 0.48g (NH4)6Mo7O 24 4H2O was dissolved in 30 mL of deionized water and ultrasonically vibrated at 40 kHz for 2 h to obtain a solution;

[0093] S2: Dissolve 0.46 g of CH4N2S and 0.1 g of CTAB (cetyltrimethylammonium bromide) in 20 mL of deionized water and stir magnetically at 300 rpm for 30 min to obtain a solution;

[0094] S3: The solution obtained in S1 was mixed with the solution obtained in S2, transferred to an autoclave, and reacted at 220°C for 18 h to obtain a D-MoS2 precursor solution;

[0095] S4: After the D-MoS2 precursor solution is naturally cooled to room temperature, it is centrifuged to obtain a precipitate, and the precipitate is washed alternately with deionized water and anhydrous ethanol, and the washing is repeated three times, and then vacuum dried to obtain a D-MoS2 composite material.

[0096] The preparation method of the heavy metal ion sensor comprises the following steps:

[0097] Step a: Add 2 mg of D-MoS2 composite material to deionized water to obtain a 2 mg / mL D-MoS2 suspension;

[0098] Step b: Pretreat the glassy carbon electrode by polishing it with 0.3 μm and 0.05 μm alumina powders in sequence until the potential difference between the oxidation peak and the reduction peak in its cyclic voltammetry curve is 60-80 mV. After completion, rinse the glassy carbon electrode with deionized water and dry it under an infrared lamp.

[0099] Step c: Pipette 6 μl of D-MoS2 suspension and evenly coat it on the surface of the pretreated glassy carbon electrode, and dry it under an infrared lamp to obtain a heavy metal ion sensor.

[0100] Comparative Example 3

[0101] The preparation method based on D-MoS2@rGO composite material includes the following steps:

[0102] S1: Weigh 0.03g graphene oxide and 0.48g (NH4)6Mo7O 24 4H2O was dissolved in 30 mL of deionized water and ultrasonically vibrated at 40 kHz for 2 h to obtain a suspension;

[0103] S2: Weigh 0.46 g of CH4N2S and 0.1 g of CTAB and dissolve them in 20 mL of deionized water. Stir magnetically at 300 rpm for 30 min to obtain a solution.

[0104] S3: The suspension obtained in S1 was mixed with the solution obtained in S2, transferred to an autoclave, and reacted at 220 °C for 18 h to obtain a D-MoS2@rGO precursor solution;

[0105] S4: After the D-MoS2@rGO precursor solution is naturally cooled to room temperature, it is centrifuged to obtain a precipitate, and the precipitate is washed alternately with deionized water and anhydrous ethanol, and the washing is repeated three times. Then, the precipitate is vacuum dried to obtain a D-MoS2@rGO composite material.

[0106] The preparation method of the heavy metal ion sensor comprises the following steps:

[0107] Step a: 2 mg of D-MoS2@rGO composite material was added to deionized water to obtain a 2 mg / mL D-MoS2@rGO suspension;

[0108] Step b: Pretreat the glassy carbon electrode by polishing it with 0.3 μm and 0.05 μm alumina powders in sequence until the potential difference between the oxidation peak and the reduction peak in its cyclic voltammetry curve is 60-80 mV. After completion, rinse the glassy carbon electrode with deionized water and dry it under an infrared lamp.

[0109] Step c: Pipette 6 μl of D-MoS2@rGO suspension and evenly coat it on the surface of the pretreated glassy carbon electrode, and dry it under an infrared lamp to obtain a heavy metal ion sensor.

[0110] Comparative Example 4

[0111] D-MoS2@Ti3C2T x The preparation method of the composite material comprises the following steps:

[0112] S1: weigh 0.03g Ti3C2T x and 0.48g(NH4)6Mo7O 24 4H2O was dissolved in 30 mL of deionized water and ultrasonically vibrated at 40 kHz for 2 h to obtain a suspension;

[0113] S2: Weigh 0.46 g of CH4N2S and 0.1 g of CTAB and dissolve them in 20 mL of deionized water. Stir the mixture magnetically at 300 rpm for 30 min to obtain a solution.

[0114] S3: The suspension obtained in S1 was mixed with the solution obtained in S2, transferred to an autoclave, and reacted at 220 °C for 18 h to obtain D-MoS2@Ti3C2T x Precursor fluid;

[0115] S4: Waiting for D-MoS2@Ti3C2T x After the precursor solution was cooled, it was centrifuged to obtain a precipitate, which was then washed alternately with deionized water and anhydrous ethanol, repeated three times, and then vacuum dried to obtain D-MoS2@Ti3C2T x Composite materials.

[0116] The preparation method of the heavy metal ion sensor comprises the following steps:

[0117] Step a: 2mgD-MoS2@Ti3C2T x The composite material was added with deionized water to obtain 2 mg / mL of D-MoS2@Ti3C2T x suspension;

[0118] Step b: Pretreat the glassy carbon electrode by polishing it with 0.3 μm and 0.05 μm alumina powders in sequence until the potential difference between the oxidation peak and the reduction peak in its cyclic voltammetry curve is 60-80 mV. After completion, rinse the glassy carbon electrode with deionized water and dry it under an infrared lamp.

[0119] Step c: Pipette 6 μl D-MoS2@Ti3C2T x The suspension is evenly coated on the surface of the pretreated glassy carbon electrode and dried under an infrared lamp to obtain a heavy metal ion sensor.

[0120] The MoS2 / GCE prepared in Comparative Example 1, the D-MoS2 / GCE prepared in Comparative Example 2, the D-MoS2@rGO / GCE prepared in Comparative Example 3, and the D-MoS2@Ti3C2T prepared in Comparative Example 4 were used. x / GCE, D-MoS2@rGO-Ti3C2T prepared in Example 1 x / GCE, D-MoS2@rGO-Ti3C2T prepared in Example 2 x / GCE and D-MoS2@rGO-Ti3C2T prepared in Example 3 x The / GCE sensor was used as the working electrode to detect the coexistence of Cd(II) and Pb(II) in water. The results are shown in Table 1:

[0121] Table 1 Comparison of the detection results of coexistence of Cd(II) and Pb(II) in each embodiment and comparative example

[0122]

[0123] It can be seen from Table 1 that MoS2 / GCE and D-MoS2@Ti3C2T x / GCE has poor detection performance for Cd(II) and Pb(II), while D-MoS2 / GCE has obvious improvement, indicating that D-MoS2 can effectively provide more electrocatalytic active sites. In addition, it was found that D-MoS2@rGO-Ti3C2T prepared in Example 1, Example 2, and Example 3 x / GCE showed better Cd(II) and Pb(II) detection performance, especially the D-MoS2@rGO-Ti3C2T prepared in Example 1. x / GCE has the highest dissolution peak current value, which may be because the defective structure of D-MoS2 serves as the electrocatalytic active center; rGO, as the growth carrier of D-MoS2, reduces the stacking of D-MoS2 nanomaterials and improves the electron mobility, thereby increasing the detection performance of the sensor for heavy metal ions in water; in addition, Ti3C2T xWhile improving the electrode conductivity, it also provides a larger space for the growth of D-MoS2 nanomaterials and the deposition of heavy metals Cd(II) and Pb(II). Therefore, the D-MoS2@rGO-Ti3C2T prepared in Example 1 x The detection performance of / GCE for Cd(II) and Pb(II) was significantly enhanced, and it also had good potential for the simultaneous determination of Cd(II) and Pb(II).

[0124] In acetic acid buffer (ABS), square wave stripping voltammetry (SWASV) was used to measure the D-MoS2@rGO-Ti3C2T prepared in Example 1. x / GCE was used as the working electrode to detect heavy metal ions Cd(II) and Pb(II). Figure 2 (a) and Figure 2 (b) D-MoS2@rGO-Ti3C2T prepared in Example 1 x / GCE standard curve for Cd(II) detection and Cd(II) dissolution curve, from Figure 2 (a) and Figure 2 (b) It can be seen that the response peak current value of the sensor electrode increases with the increase of Cd(II) concentration. When the Cd(II) concentration range is 5-600μg / L, the linear fitting equation is: ΔI=0.1822c+0.2030, R 2 =0.9943, limit of detection (LOD) was 1.35 μg / L (S / N=3); Figure 3 (a) and Figure 3 (b) D-MoS2@rGO-Ti3C2T x / GCE standard curve for Pb(II) detection and Pb(II) dissolution curve, by Figure 3 (a) and Figure 3 (b) It can be seen that the response peak current value has a good linear relationship with the concentration of Pb(II). When the concentration of Pb(II) is 5-600 μg / L, the linear fitting equation is: ΔI=0.3278c-0.6229, R 2 =0.9928, LOD (Limit of Detection) was 1.02 μg / L (S / N=3). Figure 4 (a) with Figure 4 (b) shows the calibration curve and corresponding dissolution curve for the coexistence of Cd(II) and Pb(II). When the concentrations of Cd(II) and Pb(II) are in the range of 5-400 μg / L, the linear fitting results are good. The linear fitting equation for Cd(II) is: ΔI = 0.1507c + 0.0883, R 2=0.9958, LOD is 1.63 μg / L (S / N=3), and the linear equation for Pb(II) is: ΔI=0.2716c+0.0353, R 2 =0.9916, LOD is 1.23μg / L (S / N=3). In all the above equations, "c" represents the metal ion concentration (μg / L), and "ΔI" represents the response peak current size (1e-6A). In summary, the detection limit of the two heavy metal ions is not much different from that of each alone, which indicates that D-MoS2@rGO-Ti3C2T x / GCE has good detection performance for heavy metal ions Cd(II) and Pb(II) in water.

[0125] Figure 5 (a) shows the D-MoS2@rGO-Ti3C2T prepared in Example 1 x The test results of the sensor with GCE as the working electrode in 0.1M ABS (Acetate Buffer) (pH = 4.5) containing 100 μg / L coexisting Cd(II) and Pb(II) are shown in Figure 2. Figure 5 (b) shows the D-MoS2@rGO-Ti3C2T prepared in Example 1 x The sensor with GCE as the working electrode was tested continuously in 0.1M ABS (Acetate Buffer) (pH = 4.5) containing 100 μg / L coexisting Cd(II) and Pb(II). The results showed that the dissolution peak current values of Cd(II) and Pb(II) remained relatively unchanged. The relative standard deviations (RSDs) of Cd(II) and Pb(II) were calculated to be 0.84% and 1.69%, respectively. In addition, five working electrodes were prepared under the same conditions and parallel experiments were carried out. The results are shown in Figure 2. Figure 5 (c) The average of the five groups of measured peak current values was used to calculate the RSDs of Cd(II) and Pb(II), which were 1.75% and 1.08%, respectively;

[0126] D-MoS2@rGO-Ti3C2T x / GCE was stored in a refrigerator at 4°C. The concentration of the standard Cd(II) and Pb(II) coexisting solution was 100 μg / L. The experimental data are as follows: Figure 5 As shown in (d), the results show that although the content of D-MoS2@rGO-Ti3C2T decreases slightly in a short period of time (7 days), the effect is not significant. After 30 days, the content of D-MoS2@rGO-Ti3C2T can still be maintained at 81.50% and 85.37%, and after 45 days, the content of D-MoS2@rGO-Ti3C2T can be maintained at 63.16% and 75.87%. x / GCE sensor has good repeatability and stability.

[0127] With reference to the water samples in the actual environment, the interfering ions were artificially added to explore the D-MoS2@rGO-Ti3C2T x / GCE sensor's anti-interference performance for heavy metal ions was controlled at a concentration of 100 μg / L for lead ions and cadmium ions. Other interfering ions were selected from common impurity ions in actual water samples, and the added concentration was 1000 μg / L. The experimental results are as follows: Figure 6 The presence of interfering ions K(I), Ca(II), Mg(II), Al(Ⅲ), Fe(Ⅲ), Fe(II), Mn(II), Zn(II), Cr(Ⅲ), Cu(II), chloride ions, sulfate ions, and carbonate ions has basically no effect on the detection of two heavy metal ions Cd(II) and Pb(II). In addition, the presence of Cr(Ⅲ) and Cu(II) causes a slight decrease in the detection results of Cd(II) and Pb(II), but the effect is not significant. This may be due to competition. Studies have shown that this situation can be reduced or eliminated by adding potassium ferrocyanide to form a stable precipitate.

[0128] Figure 7 (a) is the SEM image of MoS2 prepared in Comparative Example 1, where spherical MoS2 composed of nanosheets can be observed, and the size is relatively large; Figure 7 (b) The D-MoS2 prepared in Comparative Example 2 exhibits an obvious broken spherical structure, a relatively small particle size, and a reduced degree of agglomeration. This is because CTAB has a strong inhibitory effect on the layered stacking structure of MoS2, affecting the morphology of D-MoS2. Figure 7 (c) shows the D-MoS2@Ti3C2T prepared in Comparative Example 3 x The SEM image shows that the broken MoS2 nanospheres grow on the Ti3C2T x Surface and interlayer structure; Figure 7 (d) In D-MoS2@rGO, broken spherical MoS2 nanospheres can be observed growing on some locations on the rGO surface. This is probably because the oxygen-containing groups on the GO surface provide growth sites for MoS2. Figure 7 (e) and Figure 7 (f) shows the D-MoS2@rGO-Ti3C2T prepared in Example 1 x It is expressed as D-MoS2@Ti3C2T x and D-MoS2@rGO hybrid materials, broken spherical structure of MoS2 on Ti3C2T x The surface and interlayer structure and the growth of some positions on the rGO surface are Figure 7 (g) It was found that D-MoS2@rGO-Ti3C2T prepared in Example 1 xThe Ti content is extremely low, and the nanoflower structure is composed of evenly distributed Mo and S elements, and the ratio of n(Mo):n(S) is close to 1:2. This may be because Ti3C2T x The abundant oxygen-containing functional groups on the surface provide growth sites for MoS2, resulting in the formation of D-MoS2 covered on the Ti3C2T x The results show that the addition of surfactant CTAB can regulate the morphology and defect structure of MoS2, obtain a higher specific surface area and more edge active sites, and MoS2 on the carrier Ti3C2T x The growth of MoS2 on the surface of GO reduces the agglomeration of MoS2, thereby improving the detection performance of the sensor for heavy metal ions.

[0129] Figure 8 X-ray photoelectron spectroscopy (XPS) was used to analyze the elemental composition and chemical valence state of the prepared composite materials. Figure 8 (a) shows D-MoS2 (prepared in Comparative Example 2), D-MoS2@rGO (prepared in Comparative Example 3) and D-MoS2@rGO-Ti3C2T x The full spectrum characteristic peaks of (prepared in comparative example 4) are basically the same, mainly with Mo, S, C and O element peaks, and Ti element almost disappears, which may be due to the presence of MoS2 in Ti3C2T x The surface of the substrate grows and covers the support, so it mainly shows the characteristic peaks of MoS2; Figure 8 (b) shows D-MoS2@rGO-Ti3C2T x In the Mo3d fine spectrum (prepared in Example 1), four characteristic peaks were obtained by fitting. The two main peaks at 232.66eV and 229.50eV correspond to Mo 4+ 3d 3 / 2 and Mo 4+ 3d 5 / 2 , is the main valence state of molybdenum in the composite material, and Mo appears at 234.98eV 6+ The 3d peak indicates that a small amount of MoS2 is oxidized to MoO3 when exposed to air. In addition, there is an S2s peak at 226.67 eV, which may be caused by the S defect in MoS2. Figure 8 (c) shows that the fine spectrum of S2p has two characteristic peaks at 162.21eV and 161.50eV, corresponding to S2P 1 / 2 and S2P 3 / 2 , indicating the presence of divalent sulfur and confirming the existence of MoS2, Figure 8 (d) shows that three characteristic peaks were obtained by C1s fitting, namely, C-C bond at 284.8 eV, C-O-C bond at 285.92 eV, and C-O=C bond at 287.32 eV, indicating the presence of oxygen-containing functional groups on the rGO surface; Figure 8 (e) shows that there are three characteristic peaks in the Ti2P fine spectrum, 454.80eV, 458.40eV and 464.0eV corresponding to Ti-C bond, Ti-O bond and Ti2p respectively, and the Ti-C peak intensity accounts for 82.11%, indicating that Ti3C2T x The structure remains intact; Figure 8 (f) shows the peaks of the O1s fine spectrum at 529.97 eV, 531.11 eV, and 533.78 eV, corresponding to lattice oxygen, -OH, and H2O, respectively. The hydroxyl oxygen content accounts for 54.62%, indicating that the composite material has certain hydrophilicity and can provide more electrocatalytic active sites for the sensor.

[0130] Figure 9 (a) and Figure 9 (b) The TEM image of MoS2 (prepared in Comparative Example 1) shows that the MoS2 nanosphere structure is composed of nanosheets, and two groups of clear lattice fringes are observed, with d = 0.64 nm and 0.27 nm, corresponding to the (002) and (100) crystal planes of MoS2, respectively, which indicates that the MoS2 preparation was successful; Figure 9 (c) and Figure 9 In the TEM image of D-MoS2 (prepared in Comparative Example 2) in (d), nanosphere structures composed of nanosheets and lattice fringes of the (100) crystal plane (d = 0.64 nm) are also found. However, the spacing of the (002) crystal plane fringes is 0.68 nm, slightly larger than that of MoS2 prepared without adding CTAB, and the lattice fringes appear discontinuous and distorted, which may be due to the generation of defective structures. Figure 9 (e) and Figure 9 In the TEM image of D-MoS2@rGO (prepared in Comparative Example 3) in (f), two groups of lattice fringes with d = 0.68 nm and d = 0.27 nm were also observed, corresponding to the (002) crystal plane and (100) crystal plane of MoS2, respectively. The rGO surface showed wrinkles, and D-MoS2 partially grew on the rGO sheet, which could avoid the stacking of MoS2, effectively increase the electrocatalytic active sites of the composite material, and improve the detection performance of the sensor. Figure 9 (g) and Figure 9 (h) D-MoS2@rGO-Ti3C2T x In the (100) and (002) crystal plane stripes of MoS2 can also be clearly seen in (prepared in Example 1), and the lattice stripes are discontinuous and distorted, which proves that the prepared D-MoS2@rGO-Ti3C2T x (Prepared in Example 1) is rich in defect structure, and this defect structure may be caused by D-MoS2.

[0131] Figure 10The XRD patterns of the prepared nanocomposites show that compared with the MoS2 standard card (JCPDS37-1492), D-MoS2 (prepared in comparative example 2), D-MoS2@Ti3C2T x (Comparative Example 3), D-MoS2@rGO (Comparative Example 4) and D-MoS2@rGO-Ti3C2T x The (002) crystal plane of (prepared in Example 1) shifts to a slightly smaller angle (from 14.0° to 13.8°), which may be due to the defective structure of D-MoS2, resulting in an expansion of the interlayer spacing; the two characteristic peaks at 2θ of 33.4° and 59.1° correspond to the (100) and (110) crystal planes of MoS2, respectively, indicating that the preparation of D-MoS2 was successful; D-MoS2@Ti3C2T x Ti3C2T also appeared x The (002) crystal plane characteristic diffraction peak and MoS2 characteristic diffraction peak indicate that D-MoS2 is successfully deposited on Ti3C2T x Nanomaterial surface growth; the characteristic peak of graphene (JCPDS Card File No. 75-1621) does not appear in the XRD of D-MoS2@rGO, which is due to the successful reduction of GO to rGO during the hydrothermal reduction process; D-MoS2@rGO-Ti3C2T x No other interfering diffraction peaks appeared in the XRD of the composite material, indicating that the composite material did not change the structure of MoS2, and MoS2 was successfully loaded on rGO and Ti3C2T x Nanomaterial surface; In addition, D-MoS2@Ti3C2T x and D-MoS2@rGO-Ti3C2T x A new characteristic peak appears at 25.3° for the composite material, which may be due to the partial oxidation of the composite material to form MoO3 impurities when exposed to air.

[0132] Each embodiment in this specification is described in a related manner. Similar parts between the various embodiments can be referred to in conjunction with each other. Each embodiment focuses on the differences between the other embodiments. In particular, the system embodiment is generally similar to the method embodiment, so the description is relatively simple. For related parts, refer to the description of the method embodiment.

[0133] The above description is only a preferred embodiment of the present invention and is not intended to limit the scope of protection of the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present invention are included in the scope of protection of the present invention.

Claims

1. D-MoS2@rGO-Ti3C2T x The method for preparing a nanocomposite material is characterized in that: The following steps are involved: S1: Graphene oxide, Ti3C2T x , ammonium molybdate tetrahydrate, and then deionized water is added and ultrasonic vibration is performed to obtain a suspension; S2: thiourea and cetyltrimethylammonium bromide were mixed and then added into deionized water, and magnetic stirring was performed to obtain a solution; S3: The suspension obtained in S1 was mixed with the solution obtained in S2, and then transferred to an autoclave for temperature reaction to obtain D-MoS2@rGO-Ti3C2T x Precursor fluid; S4: D-MoS2@rGO-Ti3C2T x The precursor solution was centrifuged and the precipitate was taken. The precipitate was washed alternately with deionized water and anhydrous ethanol, and the washing was repeated 3-5 times. Then, the precipitate was vacuum dried to obtain D-MoS2@rGO-Ti3C2T x Nanocomposite materials.

2. D-MoS2@rGO-Ti3C2T according to claim 1 x The method for preparing a nanocomposite material is characterized in that: The addition ratio of graphene oxide, Ti3C2Tx, and ammonium molybdate tetrahydrate in S1 is 0.01-0.03 g: 0.01-0.03 g: 0.2-0.8 g.

3. D-MoS2@rGO-Ti3C2T according to claim 1 x The method for preparing a nanocomposite material is characterized in that: The addition ratio of thiourea to hexadecyltrimethylammonium bromide in S2 is 0.2-1.0 g:0.01-0.2 g.

4. D-MoS2@rGO-Ti3C2T according to claim 1 x The method for preparing a nanocomposite material is characterized in that: The parameters of ultrasonic oscillation in S1 are set as follows: ultrasonic oscillator frequency is 20-60KHz, and ultrasonic treatment time is 0.5-4h.

5. D-MoS2@rGO-Ti3C2T according to claim 1 x The method for preparing a nanocomposite material is characterized in that: The amount of deionized water added to S1 is 10-50 mL.

6. D-MoS2@rGO-Ti3C2T according to claim 1 x The method for preparing a nanocomposite material is characterized in that: The parameters of magnetic stirring in S2 are set as follows: magnetic stirrer speed is 200-800 rpm, and magnetic stirring treatment time is 5-15 min.

7. D-MoS2@rGO-Ti3C2T according to claim 1 x The method for preparing a nanocomposite material is characterized in that: The temperature-raising reaction conditions in S3 are: reaction at 160-300° C. for 6-24 hours.

8. D-MoS2@rGO-Ti3C2T according to claim 1 x The method for preparing a nanocomposite material is characterized in that: The volume ratio of suspension to solution in S3 is 3:

2.

9. A method for preparing a heavy metal ion sensor, characterized in that: The following steps are involved: Step a: D-MoS2@rGO-Ti3C2T x The nanocomposite was added to deionized water to obtain 2 mg / mL of D-MoS2@rGO-Ti3C2T x suspension; Step b: pre-treating the glassy carbon electrode; Step c: Then, 6 μl of the suspension was transferred and evenly coated on the surface of the pretreated glassy carbon electrode, and dried under an infrared lamp to obtain a heavy metal ion sensor.

10. The method for preparing a heavy metal ion sensor according to claim 9, wherein: The pretreatment method of the glassy carbon electrode in step b is: polish the glassy carbon electrode with 0.3μm and 0.05μm alumina powder in sequence until the potential difference between the oxidation peak and the reduction peak in its cyclic voltammetry curve is 60-80mV. After completion, the glassy carbon electrode is washed with deionized water and the washed electrode is placed under an infrared lamp for drying.

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