Provided are a method and system for preparing a two-dimensional material by means of a gas-phase method. The method comprises a gas-phase etching step: reacting gas having an etching effect with an MAX phase material at a first predetermined temperature, and etching a component A in the MAX phase material to obtain a two-dimensional material containing MX. The method avoids requiring the steps such as repeated cleaning, ultrasonic and centrifugal separation, and drying in preparing MXene in a liquid-phase method, greatly simplifies a preparation process, reduces the preparation cost, can achieve industrial macro preparation of MXene, and lays a foundation for application of MXene in different fields.

Methods for synthesizing macroscale 3D heteroatom-doped carbon nanotube materials (such as boron doped carbon nanotube materials) and compositions thereof. Macroscopic quantities of three-dimensionally networked heteroatom-doped carbon nanotube materials are directly grown using an aerosol-assisted chemical vapor deposition method. The porous heteroatom-doped carbon nanotube material is created by doping of heteroatoms (such as boron) in the nanotube lattice during growth, which influences the creation of elbow joints and branching of nanotubes leading, to the three dimensional super-structure. The super-hydrophobic heteroatom-doped carbon nanotube sponge is strongly oleophilic and can soak up large quantities of organic solvents and oil. The trapped oil can be burnt off and the heteroatom-doped carbon nanotube material can be used repeatedly as an oil removal scaffold. Optionally, the heteroatom-doped carbon nanotubes in the heteroatom-doped carbon nanotube materials can be welded to form one or more macroscale 3D carbon nanotubes.

Methods for synthesizing macroscale 3D heteroatom-doped carbon nanotube materials (such as boron doped carbon nanotube materials) and compositions thereof. Macroscopic quantities of three-dimensionally networked heteroatom-doped carbon nanotube materials are directly grown using an aerosol-assisted chemical vapor deposition method. The porous heteroatom-doped carbon nanotube material is created by doping of heteroatoms (such as boron) in the nanotube lattice during growth, which influences the creation of elbow joints and branching of nanotubes leading, to the three dimensional super-structure. The super-hydrophobic heteroatom-doped carbon nanotube sponge is strongly oleophilic and can soak up large quantities of organic solvents and oil. The trapped oil can be burnt off and the heteroatom-doped carbon nanotube material can be used repeatedly as an oil removal scaffold. Optionally, the heteroatom-doped carbon nanotubes in the heteroatom-doped carbon nanotube materials can be welded to form one or more macroscale 3D carbon nanotubes.

This anode active material for a lithium secondary battery is an aluminum-containing metal in which a non-aluminum phase is dispersed in an aluminum phase, the aluminum-containing metal is a rolled material rolled in one direction, and the non-aluminum phase contains any one or both of B and Ti and satisfies the following (1) and (2) in an image acquired by a method described in the following image acquisition conditions.

This anode active material for a lithium secondary battery is an aluminum-containing metal in which a non-aluminum phase is dispersed in an aluminum phase, the aluminum-containing metal is a rolled material rolled in one direction, and the non-aluminum phase contains any one or both of B and Ti and satisfies the following (1) and (2) in an image acquired by a method described in the following image acquisition conditions.

Methods for synthesizing macroscale 3D heteroatom-doped carbon nanotube materials (such as boron doped carbon nanotube materials) and compositions thereof. Macroscopic quantities of three-dimensionally networked heteroatom-doped carbon nanotube materials are directly grown using an aerosol-assisted chemical vapor deposition method. The porous heteroatom-doped carbon nanotube material is created by doping of heteroatoms (such as boron) in the nanotube lattice during growth, which influences the creation of elbow joints and branching of nanotubes leading to the three dimensional super-structure. The super-hydrophobic heteroatom-doped carbon nanotube sponge is strongly oleophilic and can soak up large quantities of organic solvents and oil. The trapped oil can be burnt off and the heteroatom-doped carbon nanotube material can be used repeatedly as an oil removal scaffold. Optionally, the heteroatom-doped carbon nanotubes in the heteroatom-doped carbon nanotube materials can be welded to form one or more macroscale 3D carbon nanotubes.

Methods for synthesizing macroscale 3D heteroatom-doped carbon nanotube materials (such as boron doped carbon nanotube materials) and compositions thereof. Macroscopic quantities of three-dimensionally networked heteroatom-doped carbon nanotube materials are directly grown using an aerosol-assisted chemical vapor deposition method. The porous heteroatom-doped carbon nanotube material is created by doping of heteroatoms (such as boron) in the nanotube lattice during growth, which influences the creation of elbow joints and branching of nanotubes leading to the three dimensional super-structure. The super-hydrophobic heteroatom-doped carbon nanotube sponge is strongly oleophilic and can soak up large quantities of organic solvents and oil. The trapped oil can be burnt off and the heteroatom-doped carbon nanotube material can be used repeatedly as an oil removal scaffold. Optionally, the heteroatom-doped carbon nanotubes in the heteroatom-doped carbon nanotube materials can be welded to form one or more macroscale 3D carbon nanotubes.

A positive-electrode active material contains a compound represented by the following composition formula (1):

Li.sub.xMe.sub.yA.sub.zO.sub.F.sub.(1) where Me denotes one or more elements selected from the group consisting of Mn, Co, Ni, Fe, Al, Cu, Nb, Mo, Ti, Cr, Zr, Zn, Na, K, Ca, Mg, Pt, Au, Ru, and W, A denotes one or more elements selected from the group consisting of B, Si, and P, and the following conditions: 1.3x2.1, 0.8y1.3, 0<z0.2, 1.82.9, and 0.11.2 are satisfied. A crystal structure of the compound belongs to a space group Fm-3m.

A method for easily producing a graphite powder for use as a lithium secondary battery negative electrode material with small specific surface area while reducing energy consumption, and achieving high graphitization efficiency, includes melt-mixing a coke powder and a carbon precursor binder so that an amount of fixed carbon included in the carbon precursor binder is 5 to 15 parts by mass based on 100 parts by mass of the coke powder, to prepare a mixture, and pressing the mixture to prepare a compact, the coke powder being obtained by heating a green coke powder at 600 to 1450? C. in a non-oxidizing atmosphere, the green coke powder having a cumulative particle size at 50% in a volumetric cumulative particle size distribution of 5 to 50 ?m; heating the compact in a non-oxidizing atmosphere to effect carbonization and graphitization to obtain a graphitized compact; and grinding the graphitized compact.

The present disclosure relates to the technical field of photocatalysis/electrocatalysis, and in particular to a non-metallic high-entropy compound, and a preparation method and use thereof. In the present disclosure, the non-metallic high-entropy compound includes at least five non-metallic elements, where each of the at least five non-metallic elements has a molar proportion of 0.1% to 99.0%, and a total atomic proportion of the at least five non-metallic elements are 100%. The non-metallic high-entropy compound has a controllable band gap, an adjustable conductivity, and a desirable surface activity, and shows a catalytic reaction activity for hydrogen production by high-efficiency photocatalytic/electrocatalytic water splitting, carbon dioxide reduction, or organic pollutant degradation. Moreover, synthetic raw materials are all non-metals, which are cheap and easily available, while a synthesis process is simple and easy to implement.