Synergistic Cu Single Atoms and Ag Clusters on Molybdenum Carbide for Efficient and Regenerable Low-Temperature Water-Gas Shift Catalysis

The rational design of non-noble-metal (NNM)-based molybdenum carbide catalysts that synergistically combine strong metal–support interaction and high intrinsic activity for the low-temperature water-gas shift (LT-WGS, CO + H 2 O ⇌ H 2 + CO 2 ) reaction remains a pivotal challenge in carbide catalysis. Herein, we report a molybdenum carbide-supported CuAg catalyst featuring atomically dispersed Cu and Ag clusters synthesized via a controlled topological phase transition (H 0.34 MoO 3 → MoOC → α-MoC). The precursor reduction temperature (300 vs 350 °C) dictates the intermediate phase (H 0.34 MoO 3 vs MoO 2 ), critically controlling the final carbide structure (α-MoC vs β-Mo 2 C) and metal dispersion. This method bypasses traditional impregnation routes, ensuring strong metal–carbide interfaces for the LT-WGS reaction. The 1Cu2Ag/Mo x C catalyst exhibits high activity of 43.8 and 117.4 μmol CO ·g cat –1 ·s –1 at 150 and 180 °C, respectively, outperforming prior NNM catalysts and rivaling some of noble-metal systems. Experimental and theoretical analyses reveal that atomic Cu stabilized through Cu–C bonds serves as the primary active centers for H 2 O dissociation and CO reforming, while Ag clusters facilitate the formation of molybdenum carbide with a high specific surface area and the H 2 desorption. Crucially, the dynamic regeneration of oxidized surfaces via CH 4 /H 2 treatment restores activity, thereby enabling cycled operation in the WGS reaction. Our work redefines the design principles for NNM catalysts by integrating atomic precision with regenerative stability, offering a scalable solution for energy-efficient hydrogen purification and carbon-neutral industrial processes.