Provided are 5-layered MXene materials having the formulas M.sub.5X.sub.4T.sub.x; (M′aM″b)X.sub.4T.sub.x (where a+b=5); and (M′.sub.aM″.sub.b).sub.5X.sub.4T.sub.x (where a+b=1). Also provided are related methods, compositions, and applications.

An additive manufacturing method of producing a metal alloy article may involve: Providing a supply of a metal alloy in powder form; providing a supply of a nucleant material, the nucleant material lowering the nucleation energy required to crystallize the metal alloy; blending the supply of metal alloy powder and nucleant material to form a blended mixture; forming the blended mixture into a first layer; subjecting at least a portion of the first layer to energy sufficient to raise the temperature of the first layer to at least the liquidus temperature of the metal alloy; allowing at least a portion of the first layer to cool to a temperature sufficient to allow the metal alloy to recrystallize; forming a second layer of the blended mixture on the first layer; and repeating the subjecting and allowing steps on the second layer to form an additional portion of the metal alloy article.

An additive manufacturing method of producing a metal alloy article may involve: Providing a supply of a metal alloy in powder form; providing a supply of a nucleant material, the nucleant material lowering the nucleation energy required to crystallize the metal alloy; blending the supply of metal alloy powder and nucleant material to form a blended mixture; forming the blended mixture into a first layer; subjecting at least a portion of the first layer to energy sufficient to raise the temperature of the first layer to at least the liquidus temperature of the metal alloy; allowing at least a portion of the first layer to cool to a temperature sufficient to allow the metal alloy to recrystallize; forming a second layer of the blended mixture on the first layer; and repeating the subjecting and allowing steps on the second layer to form an additional portion of the metal alloy article.

The present invention discloses a selenium-doped MXene composite nano-material and a preparation method thereof, comprising the following steps: (1) adding MXene and an organic selenium source into a dispersant, and stirring to prepare a dispersion with a concentration of 1 mg/ml to 100 mg/ml; (2) transferring the dispersion into a reaction kettle, then heating, reacting, and then naturally cooling to a room temperature; (3) washing the product obtained in the step (2) with a cleaning agent, then centrifuging to collect a precipitate, and drying the precipitate under vacuum; and (4) placing the sample obtained in the step (3) into a tubular furnace for calcination, introducing protective gas, heating, and then cooling to a room temperature to obtain the selenium-doped MXene composite nano-material. The material prepared by the present invention has high specific surface area, good electrical conductivity, cycle stability performance, rate performance and high theoretical specific capacity.

The present disclosure relates to a method for producing a metal carbide, where the method includes thermally treating a molecular precursor in an oxygen-free environment, such that the treating produces the metal carbide and the molecular precursor includes ##STR00001##
where M is the metal of the metal carbide, N* includes nitrogen or a nitrogen-containing functional group, and x is between zero and six, inclusively.

The present disclosure relates to a method for producing a metal carbide, where the method includes thermally treating a molecular precursor in an oxygen-free environment, such that the treating produces the metal carbide and the molecular precursor includes ##STR00001##
where M is the metal of the metal carbide, N* includes nitrogen or a nitrogen-containing functional group, and x is between zero and six, inclusively.

Provided are MXene-containing electrodes, display devices, electrochromic devices, and other optoelectronic devices, which devices can include transparent and/or colored MXene materials. In particular, MXenes can be used as transparent conducting electrodes based on their comparatively high electrical conductivity and high work function. An electrode, comprising: a substrate; a portion of MXene material disposed on the substrate; a hole-injection material disposed on the MXene material; an organic layer in electronic communication with the hole-injection material; and a conductor material in electronic communication with the hole-injection material.

Methods for modifying the surface termination of two-dimensional (2D) transition metal carbides (MXenes) are provided. The methods, which allow for versatile chemical modification of the terminating anions via halide exchange or substitution and elimination reactions in molten inorganic salts, provide a processing approach that is widely applicable to MXenes as a broad class of functional materials.

Methods for modifying the surface termination of two-dimensional (2D) transition metal carbides (MXenes) are provided. The methods, which allow for versatile chemical modification of the terminating anions via halide exchange or substitution and elimination reactions in molten inorganic salts, provide a processing approach that is widely applicable to MXenes as a broad class of functional materials.

The present disclosure is directed to electroacoustical devices comprising patterned MXene compositions on biaxially oriented polymer substrates and methods of making and using the same.