Valorizing N2O Exhaust via Cascade Reforming Enables Efficient Hydrogen Production on Concerted Single-Atom and Nanoparticle Ru Sites

Valorization of nitrous oxide (N 2 O), a potent greenhouse gas, through cooperative reforming with light alkanes offers a promising route toward carbon-negative hydrogen production. Here, we report a Ru 1+n /ZnO catalyst that integrates isolated ruthenium single atoms (Ru 1 ) with subnanometre ruthenium nanoparticles (Ru n ), enabling cascade N 2 O valorization coupled with propane dry reforming. The catalyst reduces noble-metal cost by ∼70% compared with Ir-based benchmarks while delivering markedly enhanced hydrogen production (145.1 mol H 2 kg cat –1 h –1 ) together with stable operation for at least 72 h. Mechanistic studies reveal that densely anchored Ru 1 sites in close proximity to Ru n electronically modulate the nanoparticles toward a more metallic state, promoting hydrocarbon activation. Meanwhile, CH x * intermediates formed on Ru n are rapidly consumed through reforming with O* species generated on satellite Ru 1 via N 2 O activation, enabling an efficient cascade reaction pathway that suppresses side reactions and enhances hydrogen generation. This work demonstrates a cooperative single-atom–nanoparticle catalytic strategy for greenhouse-gas valorization and efficient hydrogen production, providing insights into the rational design of multifunctional reforming catalysts.