Surface-hydroxylated MXene and preparation and application thereof

Abstract

The present application relates to the technical field of two-dimensional photoelectric infrared detector, especially to a surface hydroxylated MXene and its preparation and application. The preparation method of the surface hydroxylated MXene provided by the present application uses different concentrations of fully ionized strong alkali solution to controllably change the type and content of the surface adsorption groups of the two-dimensional material MXene. Compared with the complex group environment on the surface of the MXene directly prepared by the solution method, the two-dimensional material MXene provided by the present application realizes uniform hydroxylated groups on the surface, realizes controllable modulation of the energy band and electronic structure of the two-dimensional material MXene, has good size uniformity and flatness, and meets the requirements of building a semiconductor infrared detection device. The two-dimensional material transfer, electrode evaporation and photolithography technology can be used to build the MXene infrared detector. The uniformization of the surface groups of the MXene sheet layer makes the energy band gap of the two-dimensional MXene adjustable, and the electronic structure is adjustable, which greatly enriches the functionality and application scenarios of the MXene-based semiconductor infrared detector.

Description

TECHNICAL FIELD

[0001] The application relates to the technical field of two-dimensional photoelectric infrared detectors, in particular to a surface hydroxylated MXene and a preparation and application thereof. BACKGROUND

[0002] Two-dimensional materials exhibit many unique properties because their carrier migration and thermal diffusion are confined within a two-dimensional plane. In recent years, MXene, as a new type of two-dimensional material, has attracted great interest in the fields of energy, photoelectricity and electromagnetic wave protection due to its excellent metal conductivity and rich surface chemical properties. The linear optical properties (such as absorption, transmission and photoluminescence) and nonlinear optical properties (such as saturated absorption and nonlinear refractive index) of MXene are highly dependent on its energy structure (such as energy band gap, direct / indirect band gap and topological properties). Although more than 30 types of MXene have been successfully synthesized, the loss of Al atomic layers during the HF or LiF / HCl acid etching process leads to the adsorption of -OH and -F groups on the surface of Ti3C2Tx. x It is known that surface chemistry has a significant impact on the electronic structure and electrical properties of MXene and can cause it to change from metallic properties to semiconductor properties. The -OH-dominated surface termination can be conducive to the band structure regulation of MXene, and the change to a semiconductor or insulator.

[0003] On this basis, a large number of studies have been conducted on the types and electronic structures of MXene, and Ti3C2Tx x , Nb2CT x , V2CT x and other MXene materials have been developed, but the following shortcomings still exist:

[0004] (1) The loss of Al atomic layers during the HF or LiF / HCl acid etching process leads to the adsorption of -OH and -F groups on the surface of Ti3C2Tx. The simultaneous adsorption of multiple groups makes it difficult to effectively regulate the electrical properties of the material.

[0005] (2) The etching process in the fluorine-containing system causes a large number of -F groups on the surface of the two-dimensional material, which can seriously affect the electrical transport properties of MXene.

[0006] (3) There is no method to achieve high-density loading of a single group on the surface of the two-dimensional material MXene.

[0007] (4) The different end groups of MXene determine the semiconductor properties of the material, and the inability to unify the end groups affects the band regulation of MXene.

[0008] (5) The specific band structure of MXene cannot be determined, which leads to the decline of product uniformity of the MXene two-dimensional photoelectric infrared detector and affects the infrared detection performance.

[0009] Therefore, it is particularly important to develop a method for modulating the end groups on the surface of MXene to realize photoelectric devices. SUMMARY

[0010] In order to solve the above problems, the purpose of the present application is to provide a surface hydroxylated MXene and its preparation and application. Surface chemistry has a significant impact on the electronic structure and electrical properties of MXene, and can change it from metallic properties to semiconductor properties. The preparation method of the surface hydroxylated MXene provided by the present application uses different concentrations of fully ionized strong alkali solution to controllably change the type and content of the adsorbed groups on the surface of the two-dimensional material MXene. Compared with the complex group environment on the surface of the MXene directly prepared by the solution method, the two-dimensional material MXene provided by the present application realizes uniform hydroxylated groups on the surface, realizes controllable modulation of the energy band and electronic structure of the two-dimensional material MXene, has good size uniformity and flatness, and meets the requirements of building a semiconductor infrared detection device. The two-dimensional material transfer, electrode evaporation and photolithography technology can be used to build the MXene infrared detector. The uniformization of the surface groups of the MXene sheet layer makes the energy band gap of the two-dimensional MXene adjustable, and the electronic structure is adjustable, which greatly enriches the functionality and application scenarios of the MXene-based semiconductor infrared detector.

[0011] The purpose of the present application can be achieved by the following technical solutions:

[0012] The first purpose of the present application is to provide a preparation method of surface hydroxylated MXene, comprising the following steps:

[0013] (S1) mixing and reacting a ceramic precursor MAX phase, LiF and HCl to obtain a multi-layer MXene;

[0014] (S2) pretreating the multi-layer MXene prepared in step (S1), then placing it in a gas washing bottle for gas washing treatment, and then centrifuging and freeze-drying to obtain a MXene powder;

[0015] (S3) placing the MXene powder in a strong alkali solution, then sequentially performing ice bath ultrasonic treatment, room temperature stirring and freeze-drying after air isolation to obtain surface hydroxylated MXene.

[0016] In an embodiment of the present application, in step (S1), the ceramic precursor MAX phase is selected from one of Ti2AlC, Nb2AlC or V2AlC.

[0017] In an embodiment of the present application, in step (S1), the mass ratio of the ceramic precursor MAX phase, LiF and HCl is 1:1:20-30.

[0018] In an embodiment of the present application, the concentration of HCl is 6M.

[0019] In an embodiment of the present application, in step (S1), the rotation speed during the reaction is 300-600 rpm, and the temperature is 35-40℃.

[0020] In an embodiment of the present application, in step (S2), the pretreatment is washing the multilayer MXene with water and then centrifuging to obtain the precipitate.

[0021] In an embodiment of the present application, in step (S2), the washing gas treatment is carried out in an inert atmosphere.

[0022] In an embodiment of the present application, in step (S2), the rotation speed during centrifugation is 6000 rpm.

[0023] In an embodiment of the present application, in step (S3), the mass ratio of the MXene powder to the strong alkali solution is 5:1.

[0024] In an embodiment of the present application, in step (S3), the strong alkali is selected from one of NaOH and KOH, and the concentration is 10-30wt%.

[0025] A second object of the present application is to provide a surface-hydroxylated MXene prepared by the above method, wherein the surface-hydroxylated MXene has a two-dimensional sheet structure, and the length is 2pm±0.5pm.

[0026] A third object of the present application is to provide an application of the surface-hydroxylated MXene in a semiconductor infrared detection device. The present application can realize the construction of the MXene infrared detector by using the two-dimensional material transfer, electrode evaporation and photolithography technology. The dark current of the MXene infrared detector can be kept at a low level under low bias voltage. When the bias voltage is 0.1V, I dark =2.25×10 - 7 mA, and when the bias voltage is increased to 0.5V, I dark <10 -6 mA.

[0027] Compared with the prior art, the present application has the following beneficial effects:

[0028] The application provides a preparation method of surface hydroxylated MXene, which utilizes the alkali intolerance of fluorine end groups formed in the MXene etching process to completely convert the -F end groups into -OH in the presence of air and a strong alkali solution.

[0029] The preparation method of surface hydroxylated MXene provided by the application utilizes different concentrations of completely ionized strong alkali solutions to controllably change the types and contents of the adsorbed groups on the surface of the two-dimensional material MXene, and compared with the complex group environment on the surface of the MXene directly prepared by the solution method, the two-dimensional MXene provided by the application realizes uniform hydroxylated groups, and realizes controllable modulation of the energy band and electronic structure of the two-dimensional MXene.

[0030] The preparation method of surface hydroxylated MXene provided by the application finally obtains two-dimensional MXene sheets that are complete, have good size uniformity and flatness, and meet the requirements of building a semiconductor infrared detection device. By using two-dimensional material transfer, electrode evaporation and photolithography technology, the MXene infrared detector can be built. The single surface group of the MXene sheet layer makes the energy band gap of the two-dimensional MXene adjustable, and the electronic structure is adjustable, which greatly enriches the functionality and application scenarios of the MXene-based semiconductor infrared detector. BRIEF DESCRIPTION OF DRAWINGS

[0031] Figure 1 X-ray photoelectron spectroscopy of surface hydroxylated MXene in Example 1, Example 2 and Example 3.

[0032] Figure 2 Transmission electron microscope photo of surface hydroxylated MXene in Example 1.

[0033] Figure 3 Ultraviolet photoelectron spectroscopy of surface hydroxylated MXene in Example 1, Example 2 and Example 3.

[0034] Figure 4 Raman spectrum of surface hydroxylated MXene in Example 1 and Example 3 and ordinary MXene in Comparative Example 1.

[0035] Figure 5 Optical photo of MXene infrared detection device in Example 1.

[0036] Figure 6 Switching response speed of the MXene infrared detection device in Example 1 under a bias of +0.1 V. DETAILED DESCRIPTION

[0037] The application provides a preparation method of surface-hydroxylated MXene, comprising the following steps:

[0038] (S1) reacting after blending of a ceramic precursor MAX phase, LiF and HCl to obtain a multi-layer MXene;

[0039] (S2) pretreating the multi-layer MXene prepared in step (S1), and then placing the multi-layer MXene in a gas washing bottle to perform gas washing treatment, centrifuging and freeze-drying to obtain MXene powder;

[0040] (S3) placing the MXene powder in a strong alkali solution, performing ice bath ultrasonic treatment, room temperature stirring and freeze-drying in sequence after air isolation to obtain surface-hydroxylated MXene.

[0041] In an embodiment of the application, in step (S1), the ceramic precursor MAX phase is selected from one of Ti2AlC, Nb2AlC or V2AlC.

[0042] In an embodiment of the application, in step (S1), the mass ratio of the ceramic precursor MAX phase, LiF and HCl is 1:1:20-30.

[0043] In an embodiment of the application, the concentration of HCl is 6M.

[0044] In an embodiment of the application, in step (S1), the rotation speed during the reaction is 300-600 rpm, and the temperature is 35-40℃.

[0045] In an embodiment of the application, in step (S2), the pretreatment is centrifuging and taking the precipitate after washing the multi-layer MXene with water.

[0046] In an embodiment of the application, in step (S2), the gas washing treatment is performed in an inert atmosphere.

[0047] In an embodiment of the application, in step (S2), the rotation speed during the centrifuging is 6000 rpm.

[0048] In an embodiment of the application, in step (S3), the mass ratio of the MXene powder and the strong alkali solution is 5:1.

[0049] In an embodiment of the application, in step (S3), the strong alkali is selected from one of NaOH and KOH, and the concentration is 10-30wt%.

[0050] The application provides surface-hydroxylated MXene prepared by the above method, wherein the surface-hydroxylated MXene has a two-dimensional sheet structure, and the length is 2pm±0.5pm.

[0051] The application provides application of surface-hydroxylated MXene in a semiconductor infrared detection device.

[0052] The application can realize construction of the MXene infrared detector by using two-dimensional material transfer, electrode evaporation and photolithography technology.

[0053] The application will be described in detail below with reference to the drawings and specific embodiments.

[0054] In the following examples and comparative examples, if no special description is given, the reagents used are commercially available reagents, and the detection means and methods used are conventional detection means and methods in the art.

[0055] In the following examples and comparative examples, the surface-hydroxylated MXene micro-morphology is characterized by transmission electron microscopy (TEM, JEOL, JEM-2100F), and X-ray photoelectron spectroscopy is measured by (XPS, Thermo Fisher ESCALAB 250Xi) instrument.

[0056] Example 1

[0057] The present embodiment provides a surface-hydroxylated MXene and a preparation method thereof, which specifically comprises the following steps:

[0058] (S1) 1g of 200-mesh Ti2AlC is blended with 1g of LiF and 20mL of 9mol / L HCl in a polypropylene reactor, and is reacted at 35℃ for 24h under a stirring rate of 500rpm to obtain a multi-layer MXene;

[0059] (S2) The multi-layer MXene obtained in step (S1) is centrifuged at a speed of 6000rpm and washed with deionized water for 6 times, and the lower product is added to a washing bottle, deionized water is added, Ar gas is introduced for 10 minutes, and then ultrasonic treatment is performed for 1h, and then centrifuged at 6000rpm for 1h, and the upper black liquid is the MXene dispersion liquid, wherein the concentration of the MXene dispersion liquid is 8mg / mL; then the MXene dispersion liquid is freeze-dried for 24h to obtain a MXene powder;

[0060] (S3) 100mg of the MXene powder obtained in step (S2) is added to a previously configured 10mL of 10wt% KOH solution, then the reaction device is completely isolated from air by using a double-pipe, ultrasonic treatment is performed in an ice water bath for 30min, then the solution is stirred at room temperature at a speed of 500rpm for 12h, and finally freeze-dried for 24h to obtain the surface-hydroxylated MXene (powder).

[0061] The X-ray photoelectron spectroscopy of the surface-hydroxylated MXene prepared in the present embodiment is as shown in Figure 1The transmission electron microscope image is shown as Figure 2 The ultraviolet photoelectron spectrum is shown as Figure 3 The Raman spectrum is shown as Figure 4

[0062] The optical photo of the MXene infrared detection device prepared by using the surface-hydroxylated MXene prepared in the embodiment is shown as Figure 5 The switching response speed under a bias of +0.1V is shown as Figure 6

[0063] Embodiment 2

[0064] The embodiment provides a surface-hydroxylated MXene and a preparation method thereof, and specifically comprises the following steps:

[0065] (S1) 1g of 200-mesh Ti2AlC is blended with 1g of LiF and 20mL of 9mol / L HCl in a polypropylene reactor, and is reacted at 35℃ for 24h under a stirring speed of 500rpm to obtain multi-layer MXene;

[0066] (S2) The multi-layer MXene obtained in step (S1) is centrifuged at a speed of 6000rpm and washed with deionized water for 6 times, and the lower product is added to a washing bottle, deionized water is added, Ar gas is introduced for 10min, and then ultrasonic treatment is performed for 1h, and then centrifuged at 6000rpm for 1h, and the upper black liquid is the MXene dispersion liquid, wherein the concentration of the MXene dispersion liquid is 8mg / mL; then the MXene dispersion liquid is freeze-dried for 24h to obtain MXene powder;

[0067] (S3) 100mg of the MXene powder obtained in step (S2) is added into a previously configured 10mL of 20wt% KOH solution, then the reaction device is completely isolated from air by using a double-pipe, ultrasonic treatment is performed in an ice water bath for 30min, then the solution is stirred at a speed of 500rpm for 12h at room temperature, and finally freeze-drying is performed for 24h to obtain surface-hydroxylated MXene (in powder form).

[0068] The X-ray photoelectron spectrum of the surface-hydroxylated MXene prepared in the embodiment is shown as Figure 1 The ultraviolet photoelectron spectrum is shown as Figure 3

[0069] Embodiment 3

[0070] The embodiment provides a surface-hydroxylated MXene and a preparation method thereof, and specifically comprises the following steps:

[0071] ​​​(S1) Take 1 g of 200 mesh Ti2AlC, mix with 1 g of LiF and 20 mL of 9 mol / L HCl in a polypropylene reactor, react at 35°C for 24 h at a stirring rate of 500 rpm, to obtain multi-layer MXene;

[0072] (S2) The multi-layer MXene obtained in step (S1) is centrifuged at a speed of 6000 rpm and washed with deionized water for 6 times, the lower product is added to a gas washing bottle, deionized water is added, Ar gas is introduced for 10 minutes, and then ultrasonic treatment is carried out for 1 h, and then centrifuged at 6000 rpm for 1 h, the upper black liquid is MXene dispersion liquid, wherein the concentration of the MXene dispersion liquid is 8 mg / mL; then the MXene dispersion liquid is freeze-dried for 24 h to obtain MXene powder;

[0073] (S3) 100 mg of the MXene powder obtained in step (S2) is added to a previously configured 10 mL of 30 wt% KOH solution, then the reaction device is completely isolated from air by using a double pipe, ultrasonic treatment is carried out in an ice water bath for 30 min, then the solution is stirred at room temperature at a speed of 500 rpm for 12 h, and finally freeze-dried for 24 h to obtain surface-hydroxylated MXene (powder).

[0074] The X-ray photoelectron spectrum of the surface-hydroxylated MXene prepared in this example is shown in Figure 1 , the ultraviolet photoelectron spectrum is shown in Figure 3 , and the Raman spectrum is shown in Figure 4 .

[0075] Comparative Example 1

[0076] This comparative example provides ordinary MXene and a preparation method thereof, specifically comprising the following steps:

[0077] (S1) Take 1 g of 200 mesh Ti2AlC, mix with 1 g of LiF and 20 mL of 9 mol / L HCl in a polypropylene reactor, react at 35°C for 24 h at a stirring rate of 500 rpm, to obtain multi-layer MXene;

[0078] (S2) The multi-layer MXene obtained in step (S1) is centrifuged at a speed of 6000 rpm and washed with deionized water for 6 times, the lower product is added to a gas washing bottle, deionized water is added, Ar gas is introduced for 10 minutes, and then ultrasonic treatment is carried out for 1 h, and then centrifuged at 6000 rpm for 1 h, the upper black liquid is MXene dispersion liquid, wherein the concentration of the MXene dispersion liquid is 8 mg / mL; then the MXene dispersion liquid is freeze-dried for 24 h to obtain MXene powder.

[0079] The Raman spectrum of the MXene powder prepared in this comparative example is shown in Figure 4 .

[0080] The foregoing description of the embodiments has been presented for the purpose of illustration and description. It is not intended to be exhaustive or to limit the application to the precise form disclosed. Modifications and variations are possible in light of the above teachings or can be acquired from practice of the application. As well, the description is presented in the context of the preferred embodiments as a teaching of the principles of the application. The application is defined by the appended claims and their equivalents.

Claims

1. Application of surface-hydroxylated MXene in semiconductor infrared detection devices, characterized in that, The preparation method of the surface-hydroxylated MXene comprises the following steps: (S1) reacting a ceramic precursor MAX phase, LiF and HCl after blending to obtain a multi-layer MXene; (S2) pretreating the multi-layer MXene prepared in step (S1), and then placing the multi-layer MXene in a gas washing bottle for gas washing treatment, centrifuging and freeze-drying to obtain a MXene powder; (S3) placing the MXene powder in a strong alkali solution, and sequentially performing ice bath ultrasonic treatment, room temperature stirring and freeze-drying after air isolation to obtain the surface-hydroxylated MXene; In step (S1), the ceramic precursor MAX phase is selected from one of Ti2AlC, Nb2AlC or V2AlC; the mass ratio of the ceramic precursor MAX phase, LiF and HCl is 1:1:20-30; during the reaction, the rotation speed is 300-600 rpm, and the temperature is 35-40℃; In step (S2), the pretreatment is to centrifuge and take the precipitate after washing the multi-layer MXene with water; the gas washing treatment is carried out in an inert atmosphere; In step (S3), the mass ratio of the MXene powder and the strong alkali solution is 5:1; the strong alkali is selected from one of NaOH and KOH, and the concentration is 10-30wt%; by changing the concentration of the strong alkali solution, the types and contents of the adsorbed groups on the surface of the MXene are changed, so that the energy band gap and the electronic structure of the MXene are regulated; The dark current of the MXene infrared detector can be kept at a low level at a low bias voltage, I dark <10 -6 mA. 2.The application of a surface-hydroxylated MXene in a semiconductor infrared detection device according to claim 1, characterized in that, The surface-hydroxylated MXene has a two-dimensional sheet structure, and the length is 2μm ± 0.5μm.

Images