Reversible Spillover Wakens Reactivity of Dormant Modular Hydrochlorination Catalysts

Metals atomically anchored on oxides have actively realized ultimate atom efficiency. However, a “molecular cork” effect causes the intrinsically reactive sites to remain dormant in various important catalytic processes. Here, we report a strategy to waken dormant atomic Au on cobalt-doped CeO2 islands (Au/CoCeO2) that are typically recognized as barely active in acetylene hydrochlorination by precisely controlling reversible C2H2 spillover facilitated by porous carbon materials, igniting its reactivity of Au-oxo sites and enhanced stability. In this vein, the C2H2 coverage on the nitrogen-doped carbon (NC) surface reversibly spills over onto HCl-corked metal sites, uncorking the strongly bound HCl. The Au/CoCeO2 + NC system displays a 2 orders of magnitude higher activity than modular Au/CoCeO2 and obtains an enhanced catalytic activity and durability than the state-of-the-art catalyst, Au/NC. This contribution unveils a distinct Eley–Rideal-like mechanism that exists on the Au/CoCeO2 + NC system, exchanging the conventional Langmuir–Hinshelwood pathway dominated over Au/NC. Collectively, our findings reinforce the importance of taming the reaction pathways for advancing catalyst design.