关键词: 非热等离子体, 合成氨, 氮气还原, 等离子体催化, 协同催化转化

Abstract:

The decarbonization of the ammonia (NH₃) synthesis industry demands the development of energy-efficient and sustainable processes. Among various emerging approaches, non-thermal plasma (NTP) catalysis shows significant promise for overcoming the sluggish kinetics of nitrogen (N₂) activation under mild conditions while minimizing carbon emissions. Growing evidence suggests that plasma-derived hydrogen radical (H•) can serve as powerful reducing agent and direct hydrogen source to activate N₂ molecules in the gas phase. However, the efficient and sustained generation of H• species typically relies on high-power plasma dischages, leading to excessive energy consumption. In this study, we introduce a metal hydride-enhanced plasma catalysis strategy, in which TiH₂, CaH₂, and LiH act as hydrogen donors, releasing lattice hydrogen atoms as H• radicals while generating hydrogen vacancies on the surface. These vacancies are rapidly replenished by H₂ molecules, establishing a self-sustaining hydrogen-release/replenishment cycle that continuously supplies reactive H• species. As a result, this approach achieves an untrahigh NH₃ yield of 360.9 mg·h^-1·g^-1 and an energy efficiency of 9.02 g·kWh^-1 at room temperature and atmospheric pressure, surpassing most reported catalytic systems. Mechanistic studies reveal that the release of lattice hydrogen is the rate-determining step, while N₂ hydrogenation proceeds with a remarkably low energy barrier of 0.123 eV. These findings highlight the potential of metal hydrides as effective catalysts for plasma catalysis and provide valuable guidelines for the development of future catalysts aimed at energy-efficient activation of inert molecules.

Key words: Ammonia synthesis, Nitrogen reduction, Plasma catalysis, Nonthermal plasma, Catalytic conversion