Energy-Efficient Cascade Synthesis of Ammonia from Air via Spark Plasma-Mediated Nitrite Generation and CuRu Nanoalloy Electrocatalysis.

Plasma-electrocatalytic cascade ammonia synthesis offers a promising route for decentralized nitrogen fixation, yet remains hindered by excessive NO3 - formation and poor energy matching between the two stages. Here, we propose a strategy that breaks this bottleneck by selectively generating NO2 - via spark-discharge plasma and efficiently reducing it over a CuRu0.5 nanoalloy. Systematic optimization of the plasma discharge and electrocatalytic interface enables synergistic energy matching, delivering a record-low specific energy consumption of 273.41 kWh/kg NH3. Mechanistic studies reveal that Ru modulates the electronic structure of Cu, enhancing NO2 - adsorption and deoxygenation while suppressing the hydrogen evolution reaction. This work establishes a generalized paradigm for low-energy, high-selectivity ammonia synthesis from air and water.