Pt/Mo2N Catalyst Enabled by Redox Single-Site CeOx for Methanol Steam Reforming.

A perennial challenge in nanoengineered catalysis lies in the intrinsic trade-off between maximizing surface reactivity and maintaining structural robustness, which likewise plagues highly active γ-Mo2N-based catalytic materials. Here, we utilized a cryogenic engineering strategy to "freeze" the vulnerable γ-Mo2N surface, coupling with atomically dispersed redox-active Ce1Ox as a dynamic promoter on Pt-γ-Mo2N interfaces. Unlike conventional inert shields that often fail to promote catalytic efficiency, the redox-active Ce1Ox upgraded surface reaction kinetics via electronic modification, meanwhile avoiding irreversible deep oxidation of γ-Mo2N induced by scavenging excessive dissociated *O through reversible redox cycles. We show that integrating a porous, low-temperature passivated Mo2N surface with redox-active Ce1Ox sites dynamically protects against oxidation via reversible Ce3+/Ce4+ cycling while electronically modulating adjacent Pt to enhance CO adsorption and H2O dissociation, thereby achieving both superior activity and exceptional durability in low-temperature hydrogen production. Consequently, the optimized 1Pt-Ce1Ox/Mo2N-194 K catalyst achieves a record-high hydrogen production turnover number of 22,500,000 molH2/molPt alongside outstanding stability exceeding 1500 h in methanol steam reforming. This synergistic approach, merging cryogenic treatment with redox-active shielding, provides a promising paradigm to simultaneously achieve potent catalytic activation and robust structural protection in highly reactive yet inherently vulnerable nanostructures.