阅读说明：本技术 基于Ti3C2-MXene沟道的电化学晶体管传感器及制备方法、检测亚硝酸盐的方法 (Based on Ti3C2Electrochemical transistor sensor with MXene channel, preparation method of electrochemical transistor sensor and nitrite detection method ) 是由 常钢 涂博 周瑞 何云斌 于 2021-09-14 设计创作，主要内容包括：本发明涉及一种基于小尺寸超薄Ti-(3)C-(2)-MXene沟道的电化学晶体管传感器,实现了对于亚硝酸盐的高灵敏检测。该器件包括源极、漏极和栅极,源极和漏极均为铬层和金层,金层重叠于铬层上方,在源极和漏极之间用小尺寸超薄的Ti-(3)C-(2)-MXene作为导电沟道,在玻碳电极上通过循环伏安法沉积AuNPs/MXene纳米复合材料功能化修饰用作栅极。本发明所述的器件是采用一种高金属导电性、良好化学稳定性的新型二维材料Ti-(3)C-(2)-MXene作为沟道材料,构建了亚硝酸盐电化学晶体管传感器。该晶体管传感器对亚硝酸盐的检测有高灵敏度,低检测限,宽检测范围的特点,能够实现对待测液的精准检测。(The invention relates to a small-size ultrathin Ti-based material 3 C 2 -MXene channel electrochemical transistor sensor, enabling highly sensitive detection of nitrite. The device comprises a source electrode, a drain electrode and a grid electrode, wherein the source electrode and the drain electrode are both a chromium layer and a gold layer, the gold layer is overlapped above the chromium layer, and small-size ultrathin Ti is used between the source electrode and the drain electrode 3 C 2 MXene is used as a conductive channel, and AuNPs/MXene nanocomposite material is deposited on a glassy carbon electrode through cyclic voltammetry to be functionally modified and used as a grid electrode. The device adopts a novel two-dimensional material Ti with high metal conductivity and good chemical stability 3 C 2 MXene as channel material constructed nitrite electrochemical transistor sensors. The transistor sensor has the characteristics of high sensitivity, low detection limit and wide detection range for detecting nitriteAnd the accurate detection of the liquid to be detected can be realized.)

1. Based on Ti₃C₂-an MXene channel nitrite electrochemical transistor sensor, characterized by comprising a source, a drain and a gate; the channel between the source electrode and the drain electrode is small-size ultrathin Ti₃C₂-MXene; the grid is formed by depositing AuNPs and Ti by cyclic voltammetry₃C₂-glassy carbon electrodes of MXene nanocomposites.

2. The Ti-based according to claim 1₃C₂-MXene channel nitrite electrochemical transistor sensor, characterized in that said small size ultra-thin Ti₃C₂-MXene having a size of 200nm to 1 μm and a thickness of 1nm to 10 nm; the source electrode and the drain electrode are arranged on the chromium layer and the gold layer, and the gold layer is overlapped above the chromium layer.

3. Based on Ti₃C₂Nitrite electrochemical crystal of-MXene channelThe preparation method of the tube sensor is characterized by mainly comprising the following steps:

(1) selecting a source electrode and a drain electrode on a substrate respectively, wherein a channel of the electrochemical transistor sensor is arranged between the source electrode and the drain electrode;

(2) ultra-thin Ti with small size₃C₂-MXene dispersed droplets are applied between the source and drain of step (1) as a channel;

(3) and (3) electrodepositing the AuNPs/MXene nano compound on a glassy carbon electrode by a cyclic voltammetry method, and combining the AuNPs/MXene nano compound with the source electrode, the drain electrode and the channel obtained in the step (2) together to obtain the nitrite electrochemical transistor sensor.

4. The nitrite electrochemical transistor sensor of claim 3, wherein in step (2), the small-sized ultra-thin Ti₃C₂-MXene dispersion in water, Ti₃C₂-MXene concentration of 0.5-2mg/ml, drop-applied amount of 0.25-2. mu.l/mm²。

5. The nitrite electrochemical transistor sensor of claim 3, wherein said small size ultra-thin Ti₃C₂The preparation method of the-MXene dispersion liquid comprises the following steps: mixing raw material Ti₃AlC₂Adding HCl and LiF mixed solution into the mixture, and stirring the mixture at normal temperature to perform etching reaction; after the etching reaction is finished, collecting lower-layer solid and washing, fully dispersing the obtained cleaned solid in a TPAOH solution, stirring at room temperature to finish intercalation and stripping, collecting a solid product through multiple times of centrifugation, and re-dispersing the solid product in water to obtain small-size ultrathin Ti₃C₂-MXene dispersion.

6. The nitrite electrochemical transistor sensor according to claim 3, wherein in the step (3), the AuNPs/MXene nano-composite is electrodeposited on a glassy carbon electrode by cyclic voltammetry by: firstly, dropping Ti on a glassy carbon electrode₃C₂Drying the-MXene dispersion, and then placing in HAuCl₄Carrying out electrodeposition in the solution; wherein, Ti₃C₂The concentration of the MXene dispersion liquid is 0.1-1mg/ml, and the dripping amount on the glassy carbon electrode is 0.5-4 mul/mm²；HAuCl₄The concentration of the solution is 1-10 mM.

7. The nitrite electrochemical transistor sensor according to claim 3, wherein in the step (3), the cyclic voltammetry deposition voltage is-1.4-0V, the scanning speed is 20-50 mV/s, and the number of deposition cycles is 5-15 cycles.

8. The method for detecting nitrite in nitrite electrochemical transistor sensor as defined in claim 1, wherein the main steps are as follows:

first, the method is based on small-size ultrathin Ti₃C₂Immersing the-MXene nitrite electrochemical transistor sensor in a buffer solution to test a time current curve, wherein when the detection result reaches the equilibrium, the corresponding channel current value is I₀As a blank;

and step two, nitrite solutions with different concentrations are dripped into the buffer solution in the step one, the channel current value I when the balance is achieved is detected, blanks are deducted, and the current change value delta I of the channel of the electrochemical transistor sensor is obtained₀；

And thirdly, establishing a working curve for detecting the nitrite by the electrochemical transistor sensor by taking the change value delta I of the channel current of the electrochemical transistor sensor after the nitrite with different concentrations is dripped, which is measured in the second step, as a vertical coordinate and the corresponding logarithm value of the nitrite concentration as a horizontal coordinate, thereby realizing the quantitative analysis and detection of the nitrite in the liquid to be detected.

9. The method for detecting nitrite in an electrochemical transistor sensor for nitrite as defined in claim 8, wherein said buffer solution has a buffer range of 6.5-7.5.

10. The method for nitrite detection by electrochemical transistor sensor of claim 6, wherein the linear range of the working curve is 1nM-5 mM.

Technical Field

The invention relates to a small-size ultrathin Ti-based material₃C₂An electrochemical transistor with MXene channel, its preparation method, and nitrite detection method using small-size ultrathin Ti₃C₂-MXene as a channel in combination with AuNPs/MXene composite nanomaterial functionalized gate to perform subcellAnd (4) detecting nitrate.

Background

Nitrite is one of the most common detection substances in environmental analysis due to its harmful effects on the environment. It is important to develop a simple and sensitive nitrite sensor. Electrochemical transistor sensors, as a new electrochemical detection means, have higher sensitivity due to their inherent amplification characteristics, and are considered to be a promising detection means for electroanalysis. At present, most studied nitrite sensors belong to traditional electrochemical sensors, and electrochemical nitrite sensors are widely applied due to inherent advantages of low cost, reliability, simplicity, quick response and the like. However, accurate measurement of trace nitrite to meet increasing environmental safety requirements remains a significant challenge due to insufficiently low detection limits. In addition, graphene transistor sensors have also been used to detect nitrite, but the graphene channel has a lower signal due to its lower band gap.

Disclosure of Invention

Aiming at the defects in the prior art, the invention provides a small-size ultrathin Ti-based alloy₃C₂Nitrite electrochemical transistor sensor with MXene channel using small size and ultra-thin Ti between source and drain₃C₂MXene is used as a conductive channel, and AuNPs/MXene nanocomposite material is deposited on a glassy carbon electrode through cyclic voltammetry to be functionally modified and used as a grid electrode. The transistor sensor has the characteristics of high sensitivity, low detection limit and wide detection range for detecting nitrite, and can realize accurate detection of liquid to be detected.

The technical scheme adopted by the invention for solving the problems is as follows:

based on small-size ultrathin Ti₃C₂-an MXene channel nitrite electrochemical transistor sensor comprising a source, a drain and a gate; the source electrode and the drain electrode are both arranged on the chromium layer and the gold layer, the gold layer is overlapped above the chromium layer, and a channel between the source electrode and the drain electrode is small-size ultrathin two-dimensional Ti₃C₂Nanosheets (i.e., Ti)₃C₂-MXene); the grid electrode is formed by depositing gold nanoparticles by cyclic voltammetryAnd two-dimensional Ti₃C₂The composite material of nano-sheets (AuNPs/MXene) is used for realizing a functional modified glassy carbon electrode.

The invention also provides the small-size ultrathin Ti₃C₂The preparation method of the nitrite electrochemical transistor sensor with the MXene channel mainly comprises the following steps:

(1) plating a chromium layer and a gold layer on a substrate, wherein the gold layer is overlapped above the chromium layer and is used as an electrode of an electrochemical transistor sensor, a source electrode and a drain electrode are respectively selected, and a channel of the electrochemical transistor sensor is arranged between the source electrode and the drain electrode;

(2) making the small-sized ultra-thin Ti₃C₂-MXene dispersed droplets are applied between the source and drain of step (1) as a channel;

(3) and (3) electrodepositing the AuNPs/MXene nano compound on a glassy carbon electrode by a cyclic voltammetry method to be used as a grid electrode, and combining the grid electrode, the drain electrode and the channel obtained in the step (2) together to obtain the nitrite electrochemical transistor sensor.

According to the scheme, the substrate in the step (1) is mainly a glass substrate and the like, and the chromium plating and the gold plating can adopt an evaporation coating method and the like. Among them, chromium has good adhesion to glass, and it is preferable to plate chromium on a glass substrate and then plate gold on the chromium. The thickness of the chromium coating is 0.3-1nm, and the thickness of the gold coating is 30-100 nm.

According to the scheme, in the step (2), the small-size ultrathin Ti₃C₂-MXene dispersion in water, Ti₃C₂-MXene concentration 0.5-2 mg/ml; the channel area is generally 10-20mm²The amount of dripping is 5-20 μ l.

According to the scheme, the small-size ultrathin Ti₃C₂The preparation method of the (MXene) is as follows: the raw material Ti₃AlC₂Adding the mixed solution of HCl and LiF into the mixed solution and stirring the mixed solution at normal temperature; after the etching reaction is finished, centrifugally collecting lower-layer solids, and cleaning the lower-layer solids with water and ethanol to remove residual acid liquor; dispersing the cleaned solid in tetrapropylammonium hydroxide (TPAOH) solution, stirring at room temperature to complete intercalation and exfoliation, centrifuging for multiple times to collect solid product, and dispersing in deionized waterObtaining small-size ultrathin Ti in the water₃C₂-MXene dispersion.

According to the scheme, in the step (3), the method for electrodepositing the AuNPs/MXene nano compound on the glassy carbon electrode by the cyclic voltammetry comprises the following steps: firstly, dropping Ti on a glassy carbon electrode₃C₂Drying the-MXene dispersion, and then placing in HAuCl₄Carrying out electrodeposition in the solution; wherein, Ti₃C₂-MXene dispersion concentration 0.1-1 mg/ml; the area of the glassy carbon electrode is generally 5-10mm²The dripping amount is 5-20 mul; HAuCl₄The concentration of the solution is 1-10 mM.

According to the scheme, in the step (3), the cyclic voltammetry deposition voltage is-1.4-0V, the scanning speed is 20-50 mV/s, and the number of deposition turns is 5-15 turns.

The invention is based on small-size ultrathin Ti₃C₂The method for detecting nitrite by the electrochemical transistor sensor with MXene channel mainly comprises the following steps:

first, for the small-sized ultra-thin Ti₃C₂Immersing an electrochemical transistor sensor of the MXene channel in a buffer solution for testing a time current curve, wherein when the electrochemical transistor sensor is detected to reach the equilibrium, the corresponding channel current value is I₀As a blank;

secondly, nitrite solutions with different concentrations are dripped into the buffer solution immersed in the electrochemical transistor sensor in the first step, the channel current value I when the balance is achieved is detected, blanks are deducted, and the current change value delta I-I of the channel of the electrochemical transistor sensor is obtained₀；

And thirdly, establishing a working curve for detecting the nitrite by the electrochemical transistor sensor by taking the change value delta I of the channel current of the electrochemical transistor sensor after the nitrite with different concentrations is dripped, which is measured in the second step, as a vertical coordinate and taking the logarithm value of the concentration of the dripped nitrite as a horizontal coordinate, thereby realizing the quantitative analysis and detection of the nitrite in the liquid to be detected.

According to the scheme, the buffer range of the buffer solution is 7.0-7.5, and the buffer solution mainly comprises phosphoric acid buffer solution and the like.

The linear range of the working curve was 1nM to 5mM according to the protocol described above.

According to the scheme, the liquid to be detected can be natural water, including tap water, east lake water and sand lake water.

The main principle of the invention is as follows: the invention makes small-sized ultrathin Ti₃C₂The MXene is used as a conductive channel, the high electron mobility of the MXene is utilized, the AuNPs/MXene nano composite material is deposited on a glassy carbon electrode through cyclic voltammetry to be functionally modified and used as a grid, and the good catalytic performance of the AuNPs and Ti are utilized₃C₂-metal conductivity of MXene. During detection, a sensor is immersed into a buffer solution, nitrite is dripped, and then reduction reaction is carried out on the nitrite under the catalytic action of grid voltage and AuNPs/MXene to generate electron transfer, so that Ti in a channel is transferred₃C₂-MXene carrier concentration changes with consequent changes in channel current. The method detects the concentration of the nitrite to be detected through the change of the channel current. The result shows that the electrochemical transistor has extremely high sensitivity to nitrite, the detection limit reaches 1nM, and the electrochemical transistor has good application prospect in the aspect of detecting nitrite.

Compared with the prior art, the invention has the beneficial effects that:

the invention is based on small-size ultrathin Ti₃C₂Nitrite electrochemical transistor sensor with MXene channel, arranging source electrode and drain electrode on gold layer and chromium layer, and then applying Ti drop coating₃C₂The channel is formed by an MXene solution mode, the transistor device is formed by utilizing the high conductivity and the electron mobility of the channel and combining with a gate which is functionally modified by depositing an AuNPs/MXene nano composite material through a cyclic voltammetry method, the rapid detection on nitrite is realized, and the transistor device has the characteristics of high sensitivity, low detection limit, wide detection range, good chemical stability and the like, and has the advantages of simplicity and convenience in operation, no pollution, rapid response, stability, accuracy and the like.

Drawings

FIG. 1 is a schematic view of a channel structure of an electrochemical transistor sensor particularly employed in the examples;

FIG. 2 shows Ti in example 1₃C₂-SEM image of MXene channel;

FIG. 3 is an SEM image of AuNPs/MXene nanocomposite in example 1;

FIG. 4 is a time-current curve of an electrochemical transistor sensor in PBS buffer solution with different nitrite concentrations in example 1;

FIG. 5 is a graph showing the operation of the electrochemical transistor sensor for detecting nitrite in example 1;

FIG. 6 is a time-current curve of an electrochemical transistor sensor in PBS buffer solution with different nitrite concentrations in example 2;

FIG. 7 is a graph showing the operation of the electrochemical transistor sensor for detecting nitrite in example 2;

FIG. 8 is a time-current curve of an electrochemical transistor sensor in PBS buffer solution with different nitrite concentrations in example 3;

FIG. 9 is a graph of the operation of the electrochemical transistor sensor for nitrite detection in example 3.

Detailed Description

In order to better understand the present invention, the following examples are further provided to illustrate the content of the present invention, but the present invention is not limited to the following examples.

The positions and sizes of the grid electrode, the source electrode and the drain electrode on the electrochemical transistor sensor are selected by a conventional method, so that the detection of nitrite by the electrochemical transistor sensor is not influenced, and only different working curves are obtained. In the following embodiment, the gate is a glassy carbon electrode with the diameter of 3mm, the AuNPs and MXene nanometer composite materials are modified on the glassy carbon electrode, and the specific distribution condition of the source electrode and the drain electrode is that the channel spacing is 0.25 cm. As shown in particular in figure 1.

In the following examples, the small-sized ultra-thin Ti₃C₂The concrete preparation method of the MXene comprises the following steps: 10mL of 9M HCl solution were prepared and 1.00g LiF was added. Thereafter, 1.00g of Ti₃AlC₂Slowly adding into the above solution, and stirring at room temperature for 3 days. After the etching reaction is finished, centrifuging at 3000rpm to collect lower-layer solid, washing with water and ethanol, and removing residual acidAnd (4) liquid. The washed solid was dispersed in 10mL of TPAOH, and stirred at room temperature for 3 days to complete intercalation and exfoliation. Centrifuging at 12000rpm to collect solid product, re-dispersing in deionized water, centrifuging at 7000rpm to collect supernatant to obtain small-size ultrathin Ti₃C₂Aqueous dispersion of nanosheets, i.e. small size ultra-thin Ti₃C₂-MXene dispersion. The small-sized ultra-thin Ti₃C₂Concentration of MXene dispersion 5mg/ml, wherein Ti is present₃C₂-MXene has a size of 300nm-500nm and a thickness of 1nm-2 nm.

In the following examples, V set when measuring the time current curve using a digital source meter_DSIs 0.01-0.1V, V_GIt was 0.9V.

Example 1

Based on small-size ultrathin Ti₃C₂The preparation method of the nitrite electrochemical transistor sensor with the MXene channel comprises the following specific steps:

the method comprises the following steps that firstly, chromium and gold are plated on a glass substrate in sequence through an evaporation coating method, wherein the thickness of the chromium is about 0.4nm, the thickness of the gold is about 30nm, a source electrode and a drain electrode are respectively arranged, and a channel of the electrochemical transistor sensor is arranged between the source electrode and the drain electrode;

second, prepare 0.5mg/ml Ti₃C₂10. mu.l of MXene dispersion was applied between the source and drain electrodes in a droplet of 12mm area²And forming a channel after the channel is dried.

Thirdly, 10 mul of Ti with the concentration of 0.5mg/ml is firstly dripped on a disc glassy carbon electrode which is polished and cleaned and has the diameter of 3mm₃C₂MXene, 7mm drop-coated area²Drying, and placing in HAuCl₄And (2) in a precursor solution with the concentration of 10mM, performing cyclic voltammetry electrodeposition, wherein the scanning voltage is-1.4-0V, the scanning speed is 50mV/s, the number of scanning cycles is 10, obtaining the AuNPs/MXene composite nano material on the surface of a glassy carbon electrode, and combining the glassy carbon electrode with the source/drain electrode and the channel obtained in the second step to obtain the electrochemical transistor sensor for detecting nitrite.

As can be seen from fig. 2: channel of electrochemical transistor sensorTi₃C₂-MXene is a graphene-like corrugated structure with high metal conductivity and electron mobility.

As can be seen from fig. 3: AuNPs are uniformly loaded on the surface of MXene, so that the specific surface area is increased, and the catalytic capability on nitrite is improved.

The method for detecting nitrite by using the electrochemical transistor sensor comprises the following specific steps:

(1) setting V of digital source meter_DS＝0.05V、V_GThe electrochemical transistor sensor was immersed in a PBS buffer solution (0.1M, pH 7.4) at 0.9V, and when equilibrium was to be detected, the channel current value I was measured₀As a blank;

(2) after solutions of nitrite with different concentrations are dripped on the basis of the step (1), when the solutions reach balance again, reading a channel current value I, and deducting a blank current value I₀The current change value Δ I of the channel of the electrochemical transistor sensor described above is obtained as I-I₀；

Solutions of nitrite with different concentrations are added dropwise, and the corresponding relation between the nitrite concentration and the equilibrium current is shown in table 1:

TABLE 1

C(nM)	1	10	50	1×102	5×102	1×103	5×103	1×104	5×104	1×105	5×105	1×106	5×106
														ΔI(μA)	0.63	1.47	2.50	3.67	4.37	7.43	10.20	13.38	18.23	22.30	27.93	31.39	37.24

(3) Taking the channel current change value delta I of the electrochemical transistor sensor obtained in the step (2) in solutions of nitrite with different concentrations as a vertical coordinate, namelyThe logarithmic value of the nitrate concentration is an abscissa, and a working curve delta I of the electrochemical transistor sensor for detecting nitrite is set to be 1.455lgC +0.374, R²＝0.975(1nM～500μM)；ΔI＝8.237lgC- 18.816，R²0.995 (500. mu.M-5 mM), as shown in FIG. 5.

(4) Preparing a solution with nitrite concentration of 0.1mM as a solution to be detected, placing the electrochemical transistor sensor obtained in the step (2) in a buffer solution, dropwise adding the solution to be detected after the equilibrium is reached to be detected, reading the current when the reaction reaches the equilibrium, and deducting a blank I₀The current change value Δ I of the channel of the electrochemical transistor sensor described above is obtained as I-I₀Substituting the working curve obtained in the step (3) with 22.18 muA, and calculating to obtain the nitrite concentration of the solution to be tested, which is 0.095mM and has an error of about 5% with the configured concentration.

As can be seen from fig. 4: according to the time current curve of the electrochemical transistor sensor channel, the detection range is 1nM-5 mM; as can be seen from fig. 5: the current variation value of the channel of the electrochemical transistor sensor and the logarithm value of the added nitrite concentration show a better linear relationship.

Example 2

Based on small-size ultrathin Ti₃C₂The preparation method of the nitrite electrochemical transistor sensor with the MXene channel comprises the following specific steps of: the number of electrodeposition turns in the third step was 15 turns.

The specific process of the method for detecting nitrite by using the electrochemical transistor sensor is different from that of the method in the embodiment 1 in that: after the addition of nitrite solutions of different concentrations, the corresponding relationship between nitrite concentration and equilibrium current is shown in table 2:

TABLE 2

C(nM)	1	10	50	1×102	5×102	1×103	5×103	1×104	5×104	1×105	5×105	1×106	5×106
														ΔI(μA)	0.65	1.24	2.0	2.80	3.27	4.56	6.95	8.96	12.49	14.46	19.18	21.71	26.36

Fig. 7 shows a working curve for the electrochemical transistor sensor to detect nitrite, where Δ I is 1.024lgC +0.477, and R is plotted with the variation Δ I of the channel current as the ordinate and the logarithm of the nitrite concentration as the abscissa²＝0.976(1 nM～500μM)；ΔI＝5.796lgC-13.616，R²＝0.993(500μM～5mM)。

Example 3

Based on small-size ultrathin Ti₃C₂The preparation method of the nitrite electrochemical transistor sensor with the MXene channel comprises the following specific steps of: in the second step, Ti is drop-coated on the glassy carbon electrode₃C₂-MXene concentration 1 mg/ml.

The specific process of the method for detecting nitrite by using the electrochemical transistor sensor is different from that of the method in the embodiment 1 in that: after the addition of nitrite solutions of different concentrations, the corresponding relationship between nitrite concentration and equilibrium current is shown in table 3:

TABLE 3

C(nM)	1	10	50	1×102	5×102	1×103	5×103	1×104	5×104	1×105	5×105	1×106	5×106
														ΔI(μA)	0.48	1.53	2.72	3.44	4.97	6.52	8.96	11.31	14.0	15.93	18.96	20.18	22.01

The working curve of the electrochemical transistor sensor for detecting nitrite is established by taking the change value delta I of the channel current as an ordinate and the logarithm value of the nitrite concentration as an abscissa, as shown in fig. 9, wherein delta I is 1.658lgC +0.176, and R is²＝0.985(1 nM～500μM)；ΔI＝4.441lgC-6.825，R²＝0.996(500μM～5mM)。

In conclusion, the electrochemical transistor sensor of the present invention successfully designs and constructs Ti₃C₂MXene is used as a conductive channel, and AuNPs/MXene composite nano material is modified on a grid electrode for catalyzing nitrite; compared with other electrochemical detection methods, the transistor sensor has the characteristics of lower detection limit and wider detection range for detecting nitrite, and can realize accurate detection of the liquid to be detected.

The above description is only a preferred embodiment of the present invention, and it should be noted that, for those skilled in the art, many modifications and changes can be made without departing from the inventive concept of the present invention, and these modifications and changes are within the protection scope of the present invention.