Revealing synergetic structural activation of a CuAu surface during water-gas shift reaction.

Bimetallic alloy catalysts show strong structural and compositional dependence on their activity, selectivity, and stability. Often referred to as the “synergetic effect” of two metal elements in the alloys, their detailed dynamic information, structurally and chemically, of catalyst surface under reaction conditions remains largely elusive. Here, using aberration-corrected environmental transmission electron microscopy, we visualize the atomic-scale synergetic surface activation of CuAu under a water–gas shift reaction condition. The unique “periodic” structural activation largely determines the dominating reaction pathway, which is related to a possible “carboxyl” reaction route corroborated by density functional theory–based calculation and ab initio molecular dynamics simulation. These results demonstrate how the alloy surface is activated and catalyzes the chemical reaction, which provides insights into catalyst design with atom precision.