Visualizing Formation of Tungsten Carbide Model Catalyst and its Interaction with Oxygen

Abstract

Construction of model metal carbide surfaces is essential for surface catalysis studies over carbide‐based catalysts. Here, well‐controlled growth of tungsten carbide (WCx) layers on W(110) including carbon‐rich R(15×3)‐C/W(110) and carbon‐poor R(15×12)‐C/W(110) structures has been clearly demonstrated using chemical vapor deposition (CVD) on a clean W(110) surface or carbon segregation from the bulk. Low‐energy electron microscopy (LEEM) and micro‐region LEED (μ‐LEED) characterizations confirm that the R(15×12) structure forms first and then transforms to the R(15×3) structure by incorporating more carbon atoms in the CVD or surface segregation processes. Oxidation of the WCx/W(110) surfaces in O2 atmosphere removes surface carbon atoms, driving the structural transformation from R(15×3) to R(15×12) first and then to a two‐dimensional oxide surface. Our work provides a clear guide for well‐controlled growth of model WCx catalysts and the structural transformation between them.

Growth andin situcharacterization of 2D materials by chemical vapour deposition on liquid metal catalysts: a review

“…A great deal of effort has been devoted in this prominent rapidly evolving field involving in situ optical microscopy, 192,193,196,197 scanning tunnelling microscopy, [198][199][200][201] transmission electron microscopy, 202,203 scanning electron microscopy 26 and lowenergy electron microscopy. [204][205][206][207][208] Incorporation of in situ microscopy in LMCat related synthesis of 2D materials allows identification of the key factors governing the growth of individual flakes, their self-assembly, and further association into a single layer with a coherent atomic structure (Fig. 13).…”

Low-temperature growth of ultrathin and epitaxial Mo2C nanosheets via a vapor–liquid–solid process

“…[1][2][3][4][5] Recently, transition metal carbides (TMCs) have been intensively researched for their potential applications in catalysis and energy conversion owing to their nature of high electrical conductivity and electrochemical activity. [6][7][8][9] Mo 2 C belonging to the TMC family is proposed to be similar to Pt-based noble metals in electrochemistry and catalysis. It has been found to exhibit excellent hydrogen evolution reaction activity, 10 highly efficient nitrogen fixation 11 and superconductivity.…”