阅读说明：本技术 一种多孔MXene材料的制备方法 (Preparation method of porous MXene material ) 是由 刘毅 刘一卓 李涛 张利锋 原晓艳 郭守武 霍京浩 王晓飞 于 2019-10-14 设计创作，主要内容包括：本发明公开了一种多孔MXene材料的制备方法,首先将M粉、钛粉、铝粉及石墨粉进行混料,所述M粉为过渡金属粉,然后预压后高温烧结,制备出M位Ti原子固溶型MAX相,然后经磨细并过筛得到MAX相陶瓷粉体；然后将MAX相陶瓷粉体分散于高浓度氢氟酸中进行刻蚀得到MXene材料；最后将MXene材料通过低浓度氢氟酸进一步选择性刻蚀Ti<Sub>2</Sub>C位点后,得到多孔MXene4材料。本发明具有快速、稳定、工艺简单等优点,利用本发明方法可以快速制备出多孔MXene材料。(The invention discloses a preparation method of a porous MXene material, which comprises the steps of mixing M powder, titanium powder, aluminum powder and graphite powder, wherein the M powder is transition metal powder, prepressing, sintering at high temperature to prepare an M-bit Ti atom solid solution type MAX phase, and levigating and sieving to obtain MAX phase ceramic powder; then dispersing MAX phase ceramic powder in high-concentration hydrofluoric acid for etching to obtain MXene material; finally, further selectively etching Ti on the MXene material by using low-concentration hydrofluoric acid 2 After C-site, a porous MXene4 material was obtained. The method has the advantages of rapidness, stability, simple process and the like, and the porous MXene material can be rapidly prepared by the method.)

1. The preparation method of the porous MXene material is characterized by comprising the following steps:

the method comprises the following steps: mixing M powder, titanium powder, aluminum powder and graphite powder, wherein the M powder is transition metal powder, prepressing, sintering at high temperature to prepare an M-bit Ti atom solid solution type MAX phase, and levigating and sieving to obtain MAX phase ceramic powder;

step two: dispersing MAX phase ceramic powder in high-concentration hydrofluoric acid for etching to obtain MXene material;

step three: further selectively etching Ti by MXene material through low-concentration hydrofluoric acid₂After C site, obtaining the porous MXene material.

2. The method for preparing the porous MXene material according to claim 1, wherein the transition metal powder in the first step is niobium powder or vanadium powder.

3. The method for preparing the porous MXene material according to claim 1, wherein in the first step, the molar ratio of M powder to titanium powder to aluminum powder to graphite powder is (1-1.4): (0.6-1): (1.1-1.2): 1.

4. the method for preparing the porous MXene material according to claim 1, wherein the temperature for the high temperature sintering in the first step is 1350-1500 ℃ and the holding time is 4 hours.

5. The method for preparing the porous MXene material according to claim 1, wherein the MAX phase ceramic powder obtained in the first step has a particle size of 300-500 meshes.

6. The method for preparing the porous MXene material according to claim 1, wherein the second step is specifically as follows: the MAX phase ceramic powder is soaked in hydrofluoric acid aqueous solution with mass concentration of 39-41%, 1g of MAX phase ceramic powder is added into every 25-30 mL of hydrofluoric acid aqueous solution, stirring is carried out at 30-45 ℃ for 18-48 h to etch away Al layer atoms in the MAX phase, and then water washing and centrifugation are carried out until the pH of water washing liquid is 6-7, so as to obtain the MXene material.

7. The method for preparing the porous MXene material according to claim 1, wherein the third step is specifically as follows: dispersing MXene material in 10-25% hydrofluoric acid water solution, stirring at 20-35 deg.C for 10-40 min to dissolve Ti₂And C, washing and centrifuging until the pH value of a washing solution is 6-7, washing and centrifuging with absolute ethyl alcohol, and drying the obtained powder to obtain the porous MXene material, wherein 0.2-0.5g of MXene material is dispersed in 20-40mL of hydrofluoric acid aqueous solution.

8. The method for preparing the porous MXene material according to claim 1, wherein the powder drying manner is as follows: freeze drying for 2 days or vacuum drying at 60-80 deg.C for 12 hr.

Technical Field

The invention belongs to the field of two-dimensional materials, and particularly relates to a preparation method of a porous MXene material.

Background

In 2011, a transition metal carbide (MXenes) material is prepared by YuryGogotis of the university of Drexel in America and Michel Barsum in the professor of Michel by a hydrofluoric acid etching method for the first time, and is another 'graphene' two-dimensional material. MXene materials are mainly obtained by the removal of the A layer (group IIIA, IVA and VA elements) in the MAX phase by an etchant. During the reaction process, due to heat release and the loss of A-layer atoms, the MXene material presents a graphite-like layered high-specific surface area structure. However, for MXene materials, it is difficult to further increase the specific surface area of the material without intercalation exfoliation, and the exfoliation process can also result in oxidation of the material.

In type 211 MAX phase ceramics, with a typical V₂AlC MAX phase ceramics are taken as an example, and are extremely difficult to etch Al atomic layers clean in a short time, and MXene is extremely easy to oxidize due to long-time etching. Etching with high concentration hydrofluoric acid (50%) by mainstream etching method [ J.Am.chem.Soc.135,15966-15969]And a fluorine salt etching method [ J.Electrochem.Soc.164, A709-A713]For example, the Al layer in MAX phase ceramics can be etched well clean only when used at 55 ℃ for 90 hours and when used at 90 ℃ for 120 hours, respectively.

Disclosure of Invention

The invention aims to provide a preparation method of a porous MXene material, which overcomes the defects in the prior art, has the advantages of rapidness, stability, simple process and the like, and can be used for rapidly preparing the porous MXene material.

In order to achieve the purpose, the invention adopts the following technical scheme:

a preparation method of a porous MXene material comprises the following steps:

the method comprises the following steps: mixing M powder, titanium powder, aluminum powder and graphite powder, wherein the M powder is transition metal powder, prepressing, sintering at high temperature to prepare an M-bit Ti atom solid solution type MAX phase, and levigating and sieving to obtain MAX phase ceramic powder;

step two: dispersing MAX phase ceramic powder in high-concentration hydrofluoric acid for etching to obtain MXene material;

step three: further selectively etching Ti by MXene material through low-concentration hydrofluoric acid₂After C-site, a porous MXene4 material was obtained.

Further, in the first step, the transition metal powder is niobium powder or vanadium powder.

Further, in the first step, the molar ratio of M powder to titanium powder to aluminum powder to graphite powder is (1-1.4): (0.6-1): (1.1-1.2): 1.

further, the temperature of the high-temperature sintering in the first step is 1350-1500 ℃, and the heat preservation time is 4 hours.

Further, the grain diameter of the MAX phase ceramic powder obtained in the first step is 300-500 meshes.

Further, the second step is specifically as follows: the MAX phase ceramic powder is soaked in hydrofluoric acid aqueous solution with mass concentration of 39-41%, 1g of MAX phase ceramic powder is added into every 25-30 mL of hydrofluoric acid aqueous solution, stirring is carried out at 30-45 ℃ for 18-48 h to etch away Al layer atoms in the MAX phase, and then water washing and centrifugation are carried out until the pH of water washing liquid is 6-7, so as to obtain the MXene material.

Further, the third step is specifically: dispersing MXene material in 10-25% hydrofluoric acid water solution, stirring at 20-35 deg.C for 10-40 min to dissolve Ti₂And C, washing and centrifuging until the pH value of a washing solution is 6-7, washing and centrifuging with absolute ethyl alcohol, and drying the obtained powder to obtain the porous MXene material, wherein 0.2-0.5g of MXene material is dispersed in 20-40mL of hydrofluoric acid aqueous solution.

Further, the powder drying mode is as follows: freeze drying for 2 days or vacuum drying at 60-80 deg.C for 12 hr.

Compared with the prior art, the invention has the following beneficial technical effects:

the invention is based on etching Ti₂The experimental foundation of AlC 211 type MAX phase ceramic is that the Ti-C bond strength is weak, so that the etching activity is overlarge, and the Ti-C bond strength is extremely soluble in hydrofluoric acid in the etching process, so that the Ti-C bond strength is utilizedThe weak characteristic is that Ti atoms are dissolved in M sites of other 211 type MAX phase ceramics in a solid solution mode, so that the etching activity of the MAX phase ceramics can be improved, the etching time is reduced, and a porous structure can be manufactured by utilizing the influence of hydrofluoric acid on Ti-C bonds, and further the specific surface area of the material is improved. The experimental effect can be observed from fig. 2, and the porous morphology is generated after the second etching of the dilute hydrofluoric acid aqueous solution.

Drawings

FIG. 1 is the XRD pattern after the second etching reaction in example 2.

FIG. 2 is a SEM image of example 2 after a second etching reaction.

Detailed Description

Embodiments of the invention are described in further detail below:

a preparation method of a porous MXene material comprises the following steps:

the method comprises the following steps: m powder, titanium powder, aluminum powder and graphite powder are mixed according to a molar ratio (1-1.4): (0.6-1): (1.1-1.2): 1, mixing materials, namely M powder (niobium powder or vanadium powder), prepressing, sintering at 1350-1500 ℃ for 4 hours to prepare an M-bit Ti atom solid solution type MAX phase, and grinding and sieving to obtain MAX phase ceramic powder with the particle size of 300-500 meshes;

step two: soaking MAX phase ceramic powder in 39-41% hydrofluoric acid aqueous solution, adding 1g of MAX phase ceramic powder into every 25-30 mL of hydrofluoric acid aqueous solution, stirring at 30-45 ℃ for 18-48 h to etch away Al layer atoms in MAX phase, washing with water, and centrifuging until the pH of washing liquid is 6-7 to obtain MXene material;

step three: dispersing MXene material in 10-25% hydrofluoric acid water solution, stirring at 20-35 deg.C for 10-40 min to dissolve Ti₂And C, washing and centrifuging until the pH of a washing solution is 6-7, washing and centrifuging with absolute ethyl alcohol, drying the obtained powder to obtain the porous MXene material, wherein 0.2-0.5g of MXene material is dispersed in 20-40mL of hydrofluoric acid water solution, and the powder drying mode is as follows: freeze drying for 2 days or vacuum drying at 60-80 deg.C for 12 hr.

The present invention is described in further detail below with reference to examples: