Evidence for Zn-Promoted Methanol Synthesis at Low Temperature Over Zn/Cu Single-Atom Alloy Catalyst.

Unraveling the active sites of Cu/Zn catalysts for CO2 hydrogenation to methanol continues to pose a fundamental challenge, especially in clarifying the precise role of Zn promoters. Previous studies have predominantly emphasized the chemical state of Zn, while often neglecting accompanying structural changes in the Cu host. Here, we report the first direct observation of lattice expansion in nanocrystalline Cu within a bulk Zn/Cu single-atom alloy-a geometric distortion that elevates the d-band center of Cu and increases interatomic Cu distances. As evidenced by combined in situ experiments and density functional theory (DFT) calculations, these structural modifications promote the activation of both H2 and CO2, steering the reaction toward the *HCOO pathway and substantially enhancing methanol production at notably low temperatures. Our findings deliver unprecedented insight into Zn's promotional mechanism and significantly advance the mechanistic understanding of Cu/Zn catalysts for methanol synthesis.