Carbide

About: Carbide is a research topic. Over the lifetime, 36331 publications have been published within this topic receiving 503586 citations.

Porous Two‐Dimensional Transition Metal Carbide (MXene) Flakes for High‐Performance Li‐Ion Storage

Abstract: Herein we develop a chemical etching method to produce porous two-dimensional (2D) Ti3C2Tx MXenes at room temperature in aqueous solutions. The as-produced porous Ti3C2Tx (p-Ti3C2Tx) have larger sp ...

Behavior of metallic iron catalysts during Fischer-Tropsch synthesis studied with Mössbauer spectroscopy, X-ray diffraction, carbon content determination, and reaction kinetic measurements

Abstract: The conversion of unpromoted, unsupported metallic iron catalysts into carbides during Fischer-Tropsch synthesis (CO:H2:He = 1:1:3, 1 atm) was studied with Mossbauer spectroscopy, X-ray diffraction, carbon content analysis, and reaction kinetic measurements. From a comparison between experiments at different temperatures and literature data, it is concluded that both reaction conditions and the nature of the iron catalyst determine the combination of carbides that will be formed. Investigation of single-phase carbides revealed that the X-ray diffraction pattern commonly ascribed to a pseudohexagonal carbide Fe2C actually belongs to the carbide ∈′-Fe2.2C. At synthesis temperatures of 513 K and lower, unknown iron-carbon species were found, referred to as FexC. It is believed that FexC represents poorly defined structures between α-Fe and a crystallographic carbide. The behavior of metallic iron catalysts during Fischer-Tropseh synthesis at 513 K was studied in more detail as a function of time. It was found that the rate of hydrocarbon formation was initially low, passed through a maximum, and decreased thereupon, while the conversion of α-Fe into carbides started at a high rate and decreased rapidly. These results can be understood as the consequence of either a competition between bulk carbidization and hydrocarbon synthesis or a relatively slow activation of α-Fe for the formation of hydrocarbons in which bulk carbidization plays no role. Deactivation is caused by the formation of an excessive amount of inactive carbon at the surface of the catalyst.

A Two-Dimensional Zirconium Carbide by Selective Etching of Al3C3 from Nanolaminated Zr3Al3C5.

Abstract: The room-temperature synthesis of a new two-dimensional (2D) zirconium-containing carbide, Zr3C2Tz MXene is presented. In contrast to traditional preparation of MXene, the layered ternary Zr3Al3C5 material instead of MAX phases is used as source under hydrofluoric acid treatment. The structural, mechanical, and electronic properties of the synthesized 2D carbide are investigated, combined with first-principles density functional calculations. A comparative study on the structrual stability of our obtained 2D Zr3C2Tz and Ti3C2Tz MXenes at elevated temperatures is performed. The obtained 2D Zr3C2Tz exhibits relatively better ability to maintain 2D nature and strucural integrity compared to Ti-based Mxene. The difference in structural stability under high temperature condition is explained by a theoretical investigation on binding energy.

Heterostructures of Single-Walled Carbon Nanotubes and Carbide Nanorods

Abstract: A method based on a controlled solid-solid reaction was used to fabricate heterostructures between single-walled carbon nanotubes (SWCNTs) and nanorods or particles of silicon carbide and transition metal carbides. Characterization by high-resolution transmission electron microscopy and electron diffraction indicates that the heterostructures have well-defined crystalline interfaces. The SWCNT/carbide interface, with a nanometer-scale area defined by the cross section of a SWCNT bundle or of a single nanotube, represents the smallest heterojunction that can be achieved using carbon nanotubes, and it can be expected to play an important role in the future fabrication of hybrid nanodevices.