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CN-122010115-A - M'1.33R0.67M''2AlC3MAX phase synthesis method and two-dimensional M'1.33M''2C3MXene material preparation method

CN122010115ACN 122010115 ACN122010115 ACN 122010115ACN-122010115-A

Abstract

The invention relates to the technical field of preparation of transition metal carbide materials, in particular to a M ' 1.33 R 0.67 M'' 2 AlC 3 MAX phase synthesis method and a preparation method of a two-dimensional M' 1.33 M'' 2 C 3 MXene material. Aiming at the special synthesis obstacle caused by high stability of carbide of high inert M' element such as Ta, the high-purity ordered MAX phase containing Mo and Ta which cannot be obtained before is successfully synthesized by introducing R element as a phase formation promoter. The "auxiliary phase" action exerted by rare earths is critical and indispensable, and this action is not necessary in the system of the element M (such as Nb) with higher activity. The two-dimensional M' 1.33 M'' 2 C 3 MXene material prepared from the specific precursor and having an ordered vacancy structure and high performance has excellent conductivity, can be used as a carrier to be compounded with metal phosphide, and provides excellent electrocatalytic oxygen evolution performance.

Inventors

  • CUI WEIBIN
  • GUO HONGYUN
  • ZHONG HE

Assignees

  • 东北大学

Dates

Publication Date
20260512
Application Date
20260213

Claims (7)

  1. 1. A method for synthesizing M ' 1.33 R 0.67 M'' 2 AlC 3 MAX phase is characterized in that rare earth element R is used as a phase formation promoter, M' is from a group VIB, M '' is from an IVB-VB group, and the method specifically comprises the following steps: Step 1, proportioning and uniformly mixing according to the atomic mole ratio of (1-2) to (2.2-3) of M ' to R to M ' ' to Al to C=1.33 to 0.67 to 2; Step 2, pressing and forming the mixed powder; Step 3, heating to 1300-1600 ℃ at a heating rate of 5-20 ℃ per min under vacuum or inert atmosphere, and preserving heat for 0.5-10 hours, wherein the rare earth element R reduces the synthetic reaction energy barrier, inhibits the preferential formation of M '' C hetero-phase and promotes the generation of a target MAX phase; And 4, cooling to obtain the M' 1.33 R 0.67 M'' 2 AlC 3 MAX phase with high purity.
  2. 2. The method of claim 1, wherein M' is one or more of molybdenum Mo, chromium Cr, and tungsten W.
  3. 3. The method of claim 1, wherein M "is one or more of titanium Ti, zirconium Zr, hafnium Hf, vanadium V, tantalum Ta.
  4. 4. The M ' 1.33 R 0.67 M'' 2 AlC 3 MAX phase synthesis process according to claim 1, wherein the M ' and M "combination of M ' 1.33- x R 0.67 M'' 2 AlC 3 MAX phases does not include Mo-Ti, cr-V.
  5. 5. Use of a method according to any of claims 1-4 for the preparation of M ' 1.33 R 0.67 M'' 2 AlC 3 MAX phase as precursor for the preparation of two-dimensional M' 1.33 M'' 2 C 3 MXene material.
  6. 6. A preparation method of a two-dimensional M ' 1.33 M'' 2 C 3 MXene material is characterized in that M ' 1.33 R 0.67 M'' 2 AlC 3 MAX phase prepared by the preparation method according to any one of claims 1-4 is used as a precursor, and a fluorine-containing solution or fluorine ion molten salt is used for etching the precursor to remove an Al atomic layer and R atoms, so that the two-dimensional M ' 1.33 M'' 2 C 3 MXene material with an orderly vacancy and a surface bonded negative ion functional group T x is formed.
  7. 7. A two-dimensional M ' 1.33 M'' 2 C 3 M Xene material prepared by the preparation method according to claim 6, characterized in that as a carrier, feCoNi-based MOF is grown in situ by electrostatic self-adsorption, and (FeCoNi) P/M' 1.33 M'' 2 C 3 composite material is obtained by annealing and phosphating processes.

Description

M '1.33R0.67M''2AlC3 MAX phase synthesis method and preparation method of two-dimensional M' 1.33M''2C3 MXene material Technical Field The invention relates to the technical field of transition metal carbide material preparation, in particular to an M '1.33R0.67M''2AlC3 MAX phase synthesis method, a two-dimensional M' 1.33M''2C3 MXene material preparation method, a high-inertia metal ordered MAX phase controllable preparation method based on rare earth key effect and a two-dimensional derivative. Background The MAX phase material is ternary carbide or nitride with a nano lamellar structure, and the chemical formula is M n+1AXn, wherein M is a pre-transition metal element of III B, IV B, V B and VI B, A is mainly an element of III A and IV A, and X is carbon or nitrogen. MAX phase unit cells are formed by stacking M n+1Xn units alternately with a atomic planes, n=1, 2,3 or 4, commonly referred to simply as 211,312,413 and 514 phases. Atoms in the M n+1Xn unit are connected by strong covalent bonds, and the M n+1Xn unit and the A unit are connected by weak metal bonds, so that the strong difference of the bonds provides possibility for etching into two-dimensional transition metal carbide. The conventional ternary MAX phase "MARTIN DAHLQVIST, michel W. Barsoum, johanna Rosen, MATERIALS TODAY 2024,72, 1-24" represented by M2AlC(M = Ti, V, Nb, Ta)、M3AlC2(M = Ti)、M4AlC3(M = V, Nb, Ta) has been studied in a relatively large number. In recent years, researchers have successfully prepared multi-transition metal MAX phase solid solutions comprising two (e.g., M', M ") and more transition metals by an M-site elemental alloying process. In a system where n≥2, at some specific element collocations and ratios, the different kinds of transition metal atoms are no longer randomly distributed, but rather tend to occupy specific crystallographic positions (M ', M″ atoms occupy the outer and inner layers, respectively, of the M n+1Xn unit), thereby forming an out-of-plane ordered phase (o-MAX) of the formula M' 2M''AlC2、M'2M''2AlC3. By etching the out-of-plane ordered MAX phase, M' 2M''C2、M'2M''2C3 two-dimensional out-of-plane ordered carbide (o-MXene) can be obtained. This atomic ordering placeholder provides the opportunity to tailor the physicochemical properties of its MXene precisely. However, such out-of-plane ordered carbides (n=3) are present only in very limited amounts in collocations with certain specific elements. Only Mo2Ti2AlC3, Mo2Nb2AlC3, Cr2V2AlC3 and Cr 2Ti2AlC3 MAX phases have been successfully reported to be synthesized at present, which is probably caused by the large difference of the reactivity of different transition metal elements. This activity is primarily dependent on the bond energy (or enthalpy or formation energy) of its carbide and the atomic diffusivity. For example, in the search for new MAX phases, researchers have naturally tried to replace Nb in the known system Mo 2Nb2AlC3 with Ta, a cognate element thereof, in order to obtain Mo 2Ta2AlC3. However, this seemingly simple substitution of the same elements suffers from unexpected failure, the root cause of which is the critical difference in thermodynamic stability of the carbides of Nb and Ta. According to MATERIALS PROJECT database, the predicted formation energy of tantalum carbide (TaC) with space group Fm-3m [225] was-0.659 eV/atom, while niobium carbide (NbC) was-0.536 eV/atom. This data clearly shows that TaC is thermodynamically more stable than NbC. In the high temperature solid phase reaction of MAX phase synthesis, this critical difference in thermodynamic stability leads to the distinct result that the reaction path can lead to the formation of quaternary MAX phases for Nb-based systems, whereas for Ta-based systems the preference for extremely stable TaC binary compounds is strongly given, thus completely suppressing the complex quaternary lamellar reactions between molybdenum, aluminum, tantalum, carbon. In the current MAX phase material research field, the realization of high-quality synthesis of high-inertia multi-transition metal (such as tantalum Ta) ordered MAX phase is still a remarkable technical bottleneck. When facing high inert metal, the traditional synthesis method is difficult to realize atomic-level ordered arrangement due to the problems of large chemical potential difference among elements, mismatching diffusion rate, easy formation of competitive heterophase (such as carbide or intermetallic compound) and the like, so that the purity of a product is low, structural defects are many, and the uniformity of element distribution is poor. At present, research groups at home and abroad have made certain progress in expanding MAX phase components through a high entropy strategy or a solid phase reaction method, for example, M 4AlC3 phase containing various transition metals is synthesized, but the focus is mostly focused on improving the configuration entropy to stabilize disordered solid solutions or on metal elemen