Synergistic Cu Single Atoms and Ag Clusters on Molybdenum Carbide for Efficient and Regenerable Low-Temperature Water-Gas Shift Catalysis
Jiancong Fang, Rui Gao, Xiao Zhang, Xingjie Peng, Yifan Li, Yi Cui, Bingbing Chen, Wu Zhou, Mi Peng, Ding Ma, Chuan Shi
Abstract
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.