Atomic Scale Stability of Tungsten-Cobalt Intermetallic Nanocrystals in Reactive Environment at High Temperature.

Catalyst design plays vital roles in the structurally relevant reactions. Revealing the catalyst structure and chemistry in the reactive environment at the atomic scale is imperative for the rational design of catalysts as well as the investigation of reaction mechanism, while in situ characterization at the atomic scale in high temperature is still a great challenge. Here, tracking intermetallic Co7W6 nanoparticles with a defined structure and a high melting point by environmental aberration-corrected transmission electron microscope in combination with in situ synchrotron X-ray absorption spectroscopy, we directly present the structural and chemical stability of the Co7W6 nanocrystals in methane, carbon monoxide, and hydrogen at the temperature of 700-1100 C. The evidences are in situ and real time with both atomic scaled resolution and collective information. The results are helpful in revealing the mechanism of structural-specified synthesis of single-walled carbon nanotubes. This research offers an example of systematic investigation at atomic scale on catalysts under reactive condition. Such kind of catalysts presenting high structural stability may also find applications in other structure-specific synthesis.