In Situ Observation of Reaction-Intermediate-Mediated Dynamic Evolution of Step Sites on Au(200) Surface.

The surface structure of a metal catalyst is key to its catalytic activity and selectivity. Therefore, exploring its evolution during the catalytic reaction is vital. This study investigated the dynamic evolution of step sites on a nanoporous Au(200) surface during methane pyrolysis through in situ gas-phase transmission electron microscopy. The results indicated that the step structure migrated laterally on the surface during methane pyrolysis through a continuous process of disappearance and reconstruction. First-principles calculations revealed that adsorbed carbon species weakened the interactions between the Au atoms and their neighboring Au atoms, promoting their migration and release, which reconstructed the atomic structure of the step edge on the Au(200) surface. This study revealed profound insights into the mechanisms by which reaction intermediates induce the dynamic evolution of catalytic active sites during heterogeneous catalytic reactions. These findings provide a theoretical basis for designing and developing next-generation high-efficiency catalysts.