CN106145951A - A kind of porous two dimension transition metal carbide and preparation method thereof - Google Patents

Abstract

The invention provides a porous two-dimensional transition metal carbide. By setting holes in the MXenes material, it is beneficial to improve the specific surface area of the MXenes material, and the ability of the MXenes material to adsorb and transport particles. It can be used in the fields of electronics, energy storage, etc. It has a good application prospect. In addition, the present invention uses the MAX phase solid solution material doped with Cr at the M site as a precursor, and through selective etching, Al atoms are etched out from the MAX phase solid solution to form an MXenes sheet structure while at least part of the Cr atoms The pore structure is also formed by etching and detaching from the MAX phase solid solution. This method is simple and easy, and the MXenes sheet material with a pore structure can be prepared in one step, and the number and pore size of the pores can be determined by the etching time and the doping of Cr elements. controlled by quantity.

Description

A kind of porous two-dimensional transition metal carbide and its preparation method

technical field

The invention relates to the technical field of transition metal carbide layered ceramic materials, in particular to a porous two-dimensional transition metal carbide and a preparation method thereof.

Background technique

Graphene is currently the most studied two-dimensional crystal. Since it was discovered by Geim and Novoselov in 2004, it has received great attention in just ten years. Graphene is a new type of two-dimensional atomic crystal composed of single atomic layers of carbon atoms connected by sp ² hybridization. The bands intersect at the Fermi level, and the energy gap is zero; the carriers exhibit a linear dispersion relationship at the Fermi level, which has peculiar properties: the thermal conductivity is as high as 5150J/(m K), and the current-carrying The ion mobility reaches 1.5×10 ⁴ cm ² ·V ^-1 ·s ^-1 , and the theoretical value of the specific surface area is 2630m ² /g. It is widely used in electronics, electromagnetics, optics, sensors, catalysis, energy storage and many other fields. It shows great application potential.

Punching holes on the surface of graphene can further increase the specific surface area of graphene, and suitable holes can also become channels or storage spaces for small particles to shuttle. Wen et al. found that porous graphene is a good supercapacitor electrode material, especially under fast charge and discharge conditions, it can still maintain a high specific capacitance (200F/g at 1V/s) and structural stability (cycle 5000 After several times, the specific capacitance remains above 97% of the initial value) (Wen, Z.H., et al., Adv. Mater., 2012, 24, 5610). Sint et al. found that graphene pores modified with different functional groups can be selective for different ions. For example, negatively charged F-N modified pores are conducive to the passage of cations, while positively charged H modified pores are good for anions. Channel (Sint, K. et al., J. Am. Chem. Soc., 2008, 130, 16448). Wells et al applied porous graphene to the determination of DNA sequence. They found through simulation that when DNA passes through the holes on the graphene, the nucleotides in the DNA will have ions to hinder the current generation, and this value is related to the type of nucleotides (Wells, D.B., et al., Nano Lett., 2012, December, 4117).

At present, there are many methods for preparing porous graphene, which can be divided into polymer construction method, plasma beam, electron beam or photon beam etching method, template method and chemical etching method. Bieri et al. used benzene iodide as a precursor to polymerize for the first time to obtain a two-dimensional hexagonal network structure constructed by benzene rings. The structure has a pore size of about The pores are distributed uniformly and periodically (Bieri, M., Chem. Commum., 2009, 6919). Akhavan uses the photocatalytic activity of ZnO nanorods to obtain porous graphene of about 300nm in graphene oxide. The advantage of this method is that the size of the holes can be adjusted by the diameter of ZnO nanorods, but the pore distribution density needs to be further improved (Akhavan, O. ACS Nano, 2010, 4, 4174). Jung et al. used the Au nano-network structure as a template, and obtained uniform and densely distributed porous graphene with a diameter of about 100 nm by etching with AAO process (Jung, I., et al., Appl. Phys. Lett., 2013, 103, 023105 .). Zhu et al. used KOH solution to etch microwave-treated graphene oxide to obtain nanoscale porous graphene. This method is simple and effective, and can increase the specific surface area of porous graphene to 3100m ² /g (Zhu, Y. et al., Science, 2011, 332, 1537).

Two-dimensional transition metal carbides or carbonitrides (MXenes) are ceramic materials with a two-dimensional sheet structure discovered by Gogotsi and Barsoum et al. in 2011, which can generally be represented by M _n+1 X _n T _z , where M Refers to transition metals (such as Ti, Zr, Hf, V, Nb, Ta, Cr, Sc, etc.), X refers to C or/and N, n is generally 1-3, and T _z refers to surface groups (such as O ^2- , OH ^- , F ^- , NH ₃ , NH ₄ ⁺ etc.). At present, MXenes are generally derived from ternary layered cermets M _n+1 AX _n phase (M is a transition metal element, A is a main group element, X is C and/or N, n is generally 1 to 3, referred to as MAX phase ), obtained by extracting weakly bound A-site elements (such as Al atoms) in the MAX phase.

Similar to graphene, MXenes also have a two-dimensional sheet structure, high specific surface area, high electrical conductivity, etc., and have potential applications in the fields of electronics, electromagnetics, optics, sensors, catalysis, and energy storage.

For example, in terms of energy storage, M.Naguib et al. reported that V ₂ CT _z as an electrode material for lithium-ion batteries has excellent mass specific capacity (280mAhg ^-1 when the cycle rate is 1C; 125mAhg ^-1 when the cycle rate is 10C) , and can still maintain good stability after charging and discharging for 140 times (M.Naguib et al, J.Am.Chem.Soc., 2013, 135, 15966); M.Lukatskaya et al. studied the lamellar Ti ₃ C ₂ T _{x is} used as the electrode active material of the supercapacitor, and it is found that when 1M MgSO ₄ is used as the electrolyte, the specific capacitance of the material is as high as 400Fcm ^-3 when using 1A g ^-1 test current (M.Lukatskaya, et al, Science, 2013, 341, 1502 ); Recently, MWBarsoum et al. found that the supercapacitor prepared with clay-like Ti ₃ C ₂ T _z has a specific volumetric capacitance of 900F/cm ³ , which is very close to that of hydrated ruthenium oxide (1000-1500F/cm ³ ), which is higher than that of activated graphite. ene (60-100F/cm ³ ), micron-thin carbide-derived carbon electrodes (180F/cm ³ ), chemically converted graphene (260F/cm ³ ), etc. have much higher volume specific capacitance (M.Ghidiu et al, Nature , 2014, 516, 78).

In other application fields, Zhou Aiguo and others took the lead in studying the adsorption behavior of Ti ₃ C ₂ Tz nanosheets activated by NaOH on heavy metals in sewage, and found that at 323K, pH = 5.8-6.2, the material’s adsorption to Pb(Ⅱ) The maximum adsorption capacity can reach 140mg g ^-1 (Q.Peng et al, J.Am.Chem.Soc., 2014, 136, 4113); MXenes can also be used as a carrier material for Pt nanoparticles to play a catalytic role in fuel cells (YPGao et al, Solid State Sciences, 2014, 35, 62.), its composite material with Cu ₂ O can promote the decomposition of ammonium perchlorate (XHXie et al, Chem.Commun., 2013, 49, 10112.); In addition , our research group expanded the application of MXenes in the field of polymers, and found that poly N,N-dimethylaminoethyl methacrylate (PDMAEMA) branches were connected to V ₂ CT _z nanosheets, which can obtain _dual Hybrid materials with stimuli-responsive properties (Chen, J., et al., Chem. Commun., 2015, 51, 314).

On the other hand, compared with graphene, since the sheet structure of MXenes contains more than one element of carbon, MXenes has a more flexible and adjustable structure and richer and more diverse properties than Graphene. Through the current research and development of Graphene to improve its performance and broaden its applications, it is expected that research and development on the structure of MXenes materials will improve its performance and broaden its applications. However, at present, there are few researches and developments in this area, and the reported research results are only O. Mashtalir et al. found that small molecule dimethyl sulfoxide (DMSO) can spontaneously insert into the interlayer of Ti ₃ C ₂ T _z , and after ultrasonic treatment, the MXenes It has a good exfoliation effect, and several layers or even a single layer of Ti ₃ C ₂ T _z nanosheets (d-Ti ₃ C ₂ T _z ) like graphene can be obtained. Using the single layer Ti ₃ C ₂ T _z The energy storage density of nanosheets as the negative electrode active material of lithium-ion batteries reaches 410mAh g ^-1 @1C, 110mAh g ^-1 @36C, and has good cycle stability (O.Mashtalir, et al., Nat.Commun., 2013 ,4,1716).

Contents of the invention

The present invention provides a kind of MXenes material, and this material comprises transition group metal element and carbon element, has lamellar structure, and its lamellar structure has several holes, is porous MXenes material, thus helps to improve the specific surface area of MXenes, and adsorption and the ability to transport particles.

Part of the transition metal elements in the porous MXenes material can be replaced by Cr elements, the chemical formula is (M _1-x Cr _x ) ₂ C, where M is a transition metal element, including but not limited to Ti, V****** * etc., and 0≤x≤0.5.

In addition, some carbon elements in the porous MXenes material can be replaced by N elements.

In the porous MXenes material, the pore diameter is preferably 20nm-300nm.

The present invention also provides a method for preparing the above-mentioned porous MXenes material. The method uses a MAX phase solid solution material doped with Cr at the M site as a precursor, and the molecular formula of the precursor material is (M _1-x Cr _x ) _{n+ 1} AlC _n , where M is a transition metal, 0<x≤0.5, n=1-3; select etchant, under the action of etchant, Al atoms are detached from the precursor to form MXenes sheet structure, and at least part of Cr atoms are removed from out of the MAX phase solid solution, forming holes.

The M element is a transition metal element, including but not limited to Ti, V and the like.

At least part of the carbon elements in the precursor material (M _1-x Cr _x ) _n+1 AlC _n can be replaced by N elements to form the precursor material (M _1-x Cr _x ) _n+1 Al(C _{1- y} N _y ) _n , where 0≤y≤1.

The precursor materials include but are not limited to (Ti _1-x Cr _x ) ₂ AlC, (V _1-x Cr _x ) ₂ AlC, (Ti _1-x Cr _x ) ₂ Al(C _0.5 N _0.5 ), ( One of Ti _1-x Cr _x ) ₃ AlC ₂ , (V _1-x Cr _x ) ₃ AlC ₂ , (Ti _1-x Cr _x ) ₄ AlC ₃ , (V _1-x Cr _x ) ₄ AlC ₃ or a combination of several.

The etchant is not limited, and may be a single etchant, such as HF aqueous solution, NH ₄ HF ₂ aqueous solution, etc., or a composite etchant composed of fluoride salts and common acids. The fluoride salts include, but are not limited to, one or a combination of LiF, NaF, KF, NH ₄ F and the like. The acid includes but not limited to hydrochloric acid, sulfuric acid and the like. The composite etchant includes but not limited to the composite etchant composed of LiF and HCl aqueous solution.

When the etchant is HF aqueous solution, the mass percent concentration of the etchant is preferably 10%-50%.

When the etchant is NH ₄ HF ₂ aqueous solution, the molar concentration of the etchant is preferably 1-10M.

The number and diameter of the holes can be controlled by adjusting the etching time.

The number of the pores can be adjusted by adjusting the doping amount of the Cr element.

Since the etching reaction process is violent, preferably, the etchant is slowly added to the precursor powder drop by drop. Further preferably, the reaction vessel is placed in an ice-water bath to reduce the heat generated during the reaction.

In summary, the present invention increases the specific surface area of the MXenes material by setting holes in the MXenes material, and at the same time, the holes can also become a channel for particles to shuttle or store space, so it is beneficial to improve the conductivity and adsorption performance of the MXenes material. , has good application prospects in electronics, energy storage and other fields. In addition, the present invention uses the MAX phase solid solution material doped with Cr at the M site as a precursor, and through selective etching, Al atoms are etched out from the MAX phase solid solution to form an MXenes sheet structure while at least part of the Cr atoms The pore structure is also formed by etching and detaching from the MAX phase solid solution. This method is simple and easy, and the MXenes sheet material with a pore structure can be prepared in one step, and the number and pore size of the pores can be determined by the etching time and the doping of Cr elements. controlled by quantity.

Description of drawings

Figure 1a is the XRD diffraction pattern of (V _1-x Cr _x ) ₂ AlC (x=0, 0.01, 0.10) solid solution in Example 1 of the present invention before etching in hydrofluoric acid with a mass fraction of 40%;

Figure 1b is the XRD diffraction pattern of (V _1-x Cr _x ) ₂ AlC (x=0, 0.01, 0.10) solid solution etched in 40% hydrofluoric acid for 7 days in Example 1 of the present invention;

Fig. 2 is an SEM image of (V _1-x Cr _x ) ₂ AlC (x=0, 0.01, 0.10) solid solution in Example 1 of the present invention etched in hydrofluoric acid with a mass fraction of 40% for 7 days;

Fig. 3 is an XRD diffraction pattern of (V _0.90 Cr _0.10 ) ₂ AlC solid solution etched in hydrofluoric acid with a mass fraction of 40% for different times in Example 2 of the present invention;

Fig. 4 is an SEM image of (V _0.90 Cr _0.10 ) ₂ AlC solid solution etched in hydrofluoric acid with a mass fraction of 40% for different times in Example 2 of the present invention;

Fig. 5 is the sheet material obtained after etching 5 days of (V _1-x Cr _x ) ₂ AlC (x=0, 0.01, 0.10) solid solution in 40% hydrofluoric acid in Example 3 of the present invention as Cyclic voltammetry curves of supercapacitors made of raw materials at a scan rate of 100mV/s.

detailed description

The present invention will be further described in detail below with reference to the embodiments of the accompanying drawings. It should be noted that the following embodiments are intended to facilitate the understanding of the present invention, but have no limiting effect on it.

Example 1:

In this embodiment, the two-dimensional transition metal carbide is (V _1-x Cr _x ) ₂ C, 0≦x<0.1, and the metal carbide has several holes in its lamellar structure, showing a porous structure.

The preparation steps of the two-dimensional transition metal carbide with porous structure are as follows:

(1) Select the MAX phase solid solution material (V _1-x Cr _x ) ₂ AlC as the precursor, where x is 0, 0.01, 0.10 respectively. The preparation method and literature of the precursor: Chen, J., et al., The preparation method of V ₂ AlC described in Chem.Commun., 2015,51,314 is the same, and the raw material ratio and sintering temperature of the preparation precursor are shown in Table 1 below, and three different precursor materials are prepared; Table 1: (V ₁ Raw material ratio and sintering temperature of _-x Cr _x ) ₂ AlC (x=0, 0.01 or 0.10) solid solution

(2) Breaking the three kinds of precursor materials prepared in step (1) respectively, grinding them to 300 mesh, and obtaining three kinds of precursor powders with uniform particle size distribution;

(3) A hydrofluoric acid aqueous solution with a concentration of 40wt.% is selected as the corrosive agent; for comparison, 1 g of each precursor powder is placed in three plastic containers respectively, and each plastic container is soaked in water, and the corrosive agent is added drop by drop Slowly add to each precursor powder; for each precursor powder, the dropping time of the corrosive agent is greater than or equal to 5 minutes, and the dropping rate, dropping time and dropping amount of each corrosive agent are the same; the dropping is completed After that, mix evenly, let it stand for 7 days, and stir gently and fully every 12 hours;

(4) adopt polyvinylidene fluoride microporous filter membrane (PVDF, pore diameter is 0.45 μ m) as separation membrane, filter the product obtained through step (3), to separate each kind of precursor powder and hydrofluoric acid aqueous solution, then Wash thoroughly with deionized water, then wash with ethanol, and dry in vacuum at room temperature.

Use X-ray diffraction spectrum (XRD) to detect the change of the phase and crystal structure of each precursor powder before and after step (3) corrosion respectively, Fig. 1 a is the phase of each precursor powder before step (3) corrosion XRD diagram, Fig. 1b is the XRD diagram of each precursor powder corroded by step (3), as can be seen from Fig. 1a and Fig. 1b:

(1) For each precursor powder, under the selective corrosion action of the etchant, Al atoms are released from the MAX phase solid solution to form a MXenes sheet structure;

(2) Comparing the etched powders with three different Cr doping amounts, the characteristic peaks corresponding to MXenes are all at about 7.4°, so the Cr doping amount has no effect on the spacing of the final formed MXenes sheets.

The change of the lattice constant c value of MXenes calculated according to the change of the above XRD pattern is shown in Table 2 below.

Table 2: Changes of the lattice constant c value of (V _1-x Cr _x ) ₂ AlC (x=0, 0.01, 0.10) solid solution after etching

It can also be seen from Table 2 that the spacing of MXenes in the powders corroded by three different Cr doping amounts is basically the same. That is, the MXenes lamella obtained after corrosion doped with Cr is generally consistent with the lamella obtained after corrosion without doping Cr.

Use a scanning electron microscope (SEM) to observe the topography of each precursor powder obtained after step (3) corrosion, as shown in Figure 2, it shows that two-dimensional layered nanosheets have been obtained by using the above method; The comparison of (a), (b) and (c) in Figure 2 shows that when x>0, that is, when the precursor is doped with Cr, each nanosheet structure has holes with a size of about 200nm; and, in the same Under the etching conditions, the larger the Cr doping amount, the more holes will be obtained.

Example 2:

In this embodiment, exactly the same as in Embodiment 1, the two-dimensional transition metal carbide is (V _1-x Cr _x ) ₂ C, 0≤x<0.1, and the metal carbide sheet structure has several holes in the form of porous structure.

The preparation of the two-dimensional sheet material with a porous structure is exactly the same as the preparation method in Example 1, the difference is that this example focuses on the effect of etching time on the etching effect of the same precursor powder, The preparation method is as follows:

(1) Select the MAX phase solid solution material (V _0.90 Cr _0.10 ) ₂ AlC as the precursor. The preparation method of the precursor is as described in the literature: Chen, J., et al., Chem.Commun., 2015, 51, 314 V ₂ The preparation method of AlC is the same, and the raw material ratio and sintering temperature for preparing the precursor are the same as the corresponding parameters of x=0.10 in Table 1;

(2) Breaking the precursor materials prepared in step (1) respectively, and grinding them to 300 mesh to obtain precursor powders with uniform particle size distribution;

(3) A hydrofluoric acid aqueous solution with a concentration of 40wt.% is selected as the corrosive agent; for comparison, four parts of the precursor powder of 1 g are weighed, and each part is placed in four identical plastic containers as samples 1, 2, and 4. Three, four; Then, soak each plastic container in water, and slowly add the corrosive agent dropwise to each sample; for each sample, the dropping time of the corrosive agent is greater than or equal to 5 minutes, and the amount of the corrosive agent dropped into each sample The dropping rate, dropping time and dropping amount are the same; after the dropping is completed, mix evenly, let stand for 1d, 3d, 5d, 7d respectively, and stir gently and fully every 12h, that is, the sample after dropping Set aside for 1d, the dropwise sample left standstill for 3d, dropwise sample three for 5d, dropwise dropwise sample four for 7d;

(4) Using polyvinylidene fluoride microporous membrane (PVDF, 0.45 μm in pore size) as the separation membrane, filter the product obtained in step (3) to separate each sample from hydrofluoric acid aqueous solution, and then use deionized Fully rinsed with water, then rinsed with ethanol, and dried under vacuum at room temperature.

Utilize X-ray diffraction spectrum (XRD) to detect the change of phase and crystal structure of each sample before and after step (3) corrosion respectively as can be seen from Fig. 3:

(1) For each precursor powder, under the selective corrosion action of the etchant, Al atoms are released from the MAX phase solid solution to form a MXenes sheet structure;

(2) Prolonging the etching time helps more precursor powders to transform into MXenes.

Use a scanning electron microscope (SEM) to observe the topography of the powder obtained after the corrosion of each sample in step (3), as shown in Figure 4, it shows that two-dimensional layered nanosheets have been obtained using the above methods, and each nanosheet There are holes in the layer structure, and the pore size increases with time, which are 39nm in 1 day, 50nm in 3 days, 85nm in 5 days, and 140nm in 7 days. It can also be found from the comparison of (a), (b), (c) and (d) in Figure 2 that under the same etching conditions, the number of holes obtained increases with the increase of etching time.

Example 3:

In this embodiment, exactly the same as in Embodiment 1, the two-dimensional transition metal carbide is (V _1-x Cr _x ) ₂ C, 0≤x<0.1, and the metal carbide sheet structure has several holes in the form of porous structure.

The preparation of the two-dimensional sheet material with a porous structure is exactly the same as the preparation method in Example 1, the difference is that the etching time in this example is selected as 5 days, and the preparation method is as follows:

(1) Select the MAX phase solid solution material (V _1-x Cr _x ) ₂ AlC as the precursor, where x is 0, 0.01, 0.10 respectively. The preparation method and literature of the precursor: Chen, J., et al., The preparation method of V ₂ AlC described in Chem.Commun., 2015, 51, 314 is the same, wherein the raw material ratio and sintering temperature for preparing the precursor are shown in Table 1, and three different precursor materials are prepared.

(2) crushing the three kinds of precursor materials prepared in step (1) respectively, grinding to 300 mesh, and obtaining three kinds of precursor powders with uniform particle size distribution;

(3) A hydrofluoric acid aqueous solution with a concentration of 40wt.% is selected as the corrosive agent; for comparison, 1 g of each precursor powder is placed in three plastic containers respectively, and each plastic container is soaked in water, and the corrosive agent is added drop by drop Slowly add to each precursor powder; for each precursor powder, the dropping time of the corrosive agent is greater than or equal to 5 minutes, and the dropping rate, dropping time and dropping amount of each corrosive agent are the same; the dropping is completed After that, mix evenly, let it stand for 5 days, and stir gently and fully every 12 hours;

(4) adopt polyvinylidene fluoride microporous filter membrane (PVDF, pore diameter is 0.45 μ m) as separation membrane, filter the product obtained through step (3), to separate each kind of precursor powder and hydrofluoric acid aqueous solution, then Fully wash with deionized water, and then wash with ethanol, and then vacuum-dry at room temperature to obtain three kinds of two-dimensional transition metal carbides.

Same as Example 1, use X-ray diffraction spectrum (XRD) to detect the change of phase and crystal structure in each precursor powder before and after step (3) corrosion respectively, utilize scanning electron microscope (SEM) to observe each precursor The topography diagram of the powder obtained after the powder is corroded in step (3). It is found that for each precursor powder, under the selective corrosion of etchant, Al atoms are released from the MAX phase solid solution to form MXenes sheet structure, and at least part of the Cr atoms are removed from the MAX phase solid solution when x>0 Protrusion, forming holes, and the number of holes increases with the increase of x.

Each of the two-dimensional transition metal carbides prepared above is used as a raw material to make electrode sheets for supercapacitors, as follows:

After mixing each of the above-mentioned two-dimensional transition metal carbides, super carbon (Super P), and polyvinylidene fluoride (PVDF) in N-methyl-2-pyrrolidone at a mass ratio of 8.5:1.0:0.5 Apply it on the nickel foam, dry it and press it into an electrode sheet. The specific preparation method is as described in the literature (Cao, H.L. et al., Carbon, 2013, 56, 218.).

The activated carbon electrode sheet was prepared by the same method as above, and the activated carbon electrode sheet was used as a counter electrode. The reference electrode was Ag/AgCl, and its standard electrode potential was 0.2224V.

The electrochemical performance of the supercapacitor composed of the above-mentioned three electrodes is tested: the cyclic voltammetry curve is tested by a 1470E battery test system (Solartron analytical, USA), the set scan rate is 100mV/s, and the voltage window is the upper limit of the open circuit voltage , to prevent the supercapacitor from being oxidized during the experiment. The formula for calculating the specific capacitance is C=S/(V×U×m), where C is the specific capacitance, S is the integral area of the cyclic voltammetry curve, V is the scan rate, U is the voltage window, and m is the mass of the active material .

Figure 5 is the cyclic voltammetry curve of the supercapacitor when the scan rate is 100mV/s. As can be seen from Figure 5, when x=0.10 (that is, when the amount of holes is the most) the supercapacitor has a specific capacitance that is significantly higher than the other two; and when x=0 (that is, when there are no holes) the supercapacitor The specific capacitance is the smallest. The specific capacitances of the three capacitors obtained by calculating x=0, 0.01, and 0.10 are 16.2F/g, 18.3F/g, and 22.1F/g, respectively. It can be seen from this that MXenes with a porous structure have higher conductivity and have advantages in the field of improving the specific capacitance of supercapacitors.

The embodiments described above have described the technical solutions of the present invention in detail. It should be understood that the above descriptions are only specific embodiments of the present invention, and are not intended to limit the present invention. All done within the principle scope of the present invention Any modification and improvement should be included in the protection scope of the present invention.

Claims (10)

1. a porous two dimension transition metal carbide, comprises transiting group metal elements and carbon, has sheet Rotating fields, is characterized in that: its lamellar structure has some holes.

2. porous two dimension transition metal carbide as claimed in claim 1, is characterized in that: section transitions gold Belonging to element to be replaced by Cr element, chemical formula is (M_1-xCr_x)₂C, wherein M is transition metal, and 0≤x≤0.5。

3. porous two dimension transition metal carbide as claimed in claim 1, is characterized in that: at least partly carbon Element is replaced by N element.

4. porous two dimension transition metal carbide as claimed in claim 1, is characterized in that: described transition Metallic element is the one in Ti, V.

5. the porous two dimension transition metal carbide as described in any claim in Claims 1-4, its Feature is: the aperture of described hole is 20-300nm.

6. prepare porous two dimension transition metal carbide as claimed in claim 5, it is characterized in that: use M The MAX phase solid-solution material of position doping Cr element as presoma, the molecular formula of this persursor material is (M_1-xCr_x)_n+1AlC_n, wherein M is transition metal, 0 ＜ x≤0.50, n=1-3；

Selective etchant, under caustic effect, Al atom deviates to be formed two dimension transition metal from presoma Carbide platelets Rotating fields, the most at least partly Cr atom is deviate from from MAX phase solid solution, forms hole.

7. the method preparing porous two dimension transition metal carbide as claimed in claim 6, is characterized in that: Described persursor material is (Ti_1-xCr_x)₂AlC、(V_1-xCr_x)₂AlC、(Ti_1-xCr_x)₂Al(C_0.5N_0.5)、 (Ti_1-xCr_x)₃AlC₂、(V_1-xCr_x)₃AlC₂、(Ti_1-xCr_x)₄AlC₃、(V_1-xCr_x)₄AlC₃In one or several The combination planted.

8. the method preparing porous two dimension transition metal carbide as claimed in claim 6, is characterized in that: Described etching agent is the compound caustic that single caustic or fluoride salt are formed with customary acid；

As preferably, described fluoride salt is LiF, NaF, KF, NH₄In F one or several Combination, described acid is the one in hydrochloric acid, sulphuric acid；

As preferably, described caustic is HF aqueous solution, and the mass percent concentration of this caustic is 10%-50%；

As preferably, described caustic is NH₄HF₂During aqueous solution, the molar concentration of this caustic is 1-10M.

9. the method preparing porous two dimension transition metal carbide as claimed in claim 6, is characterized in that: By number and the aperture of etch period regulation and control described hole.

10. the method preparing porous two dimension transition metal carbide as claimed in claim 6, is characterized in that: The number of described hole is regulated and controled by the doping of Cr element.