A new class of air-stable electrene materials could make the long-sought “green ammonia” revolution far more practical. Researchers at the Institute of Science Tokyo report that an engineered surface electrene, BaSiN₂:O, delivers efficient nitrogen activation under comparatively mild conditions—while resisting the air and moisture sensitivity that has crippled earlier electrene catalysts.
Electrenes are unusual two-dimensional materials in which loosely bound, freely floating electrons reside at the surface. That electron abundance translates into an ultralow work function, enabling catalytic steps that would otherwise require harsher thermodynamic pushes. For ammonia synthesis, the bottleneck is the exceptionally strong triple bond of N₂, which conventional processes typically break only at high temperatures and pressures.
The team’s advance begins with chemistry-by-design. By doping barium silicon nitride (BaSiN₂) with a small amount of oxygen, they create BaSiN₂:O, a surface that hosts floating electrons while remaining stable in air. The key is a reversible protection mechanism that acts only when nitrogen is present.
When the material is exposed to N₂, its surface electrons spontaneously transfer to nitrogen molecules. The result is a temporary nitrogen passivation layer that chemically adsorbs onto the surface and shields the electrene from degrading reactions with air. In subsequent hydrogen exposure, the adsorbed nitrogen is hydrogenated and released as ammonia, restoring the floating-electron state so the cycle can repeat.
To push the reaction beyond nitrogen activation, the researchers add ruthenium (Ru) nanoparticles. Ru improves hydrogen activation, helping convert the protected nitrogen pathway into ammonia at a substantially higher rate.
In reported tests, Ru/BaSiN₂:O achieves an ammonia synthesis rate of 43 mmol g⁻¹ h⁻¹ at 300 °C and 0.9 MPa. The performance surpasses previously reported electride-, hydride-, and conventional Ru-based catalysts under similar low-temperature conditions.
Equally important for real-world deployment, the catalyst holds up. It retains its crystal structure after one week of air exposure and maintains activity through repeated air exposure cycles, demonstrating durability beyond what most electrene materials can offer.
Beyond the specific ammonia case, the researchers argue the strategy is general: oxygen doping plus a reversible nitrogen passivation process may provide a roadmap to electrene catalysts that combine high activity with long-term chemical stability.
Finally, the work positions surface electrens as more than laboratory curiosities—suggesting a path toward catalysts that can support sustainable chemical manufacturing without extreme operating environments, and potentially enabling future electronics- and physics-driven applications of stable floating-electron surfaces.
Subject of Research:
Nature Communications — ammonia synthesis using an air-stable surface electrene (Ru/BaSiN₂:O)
Article Title:
Creation of an air-stable surface electrene and its application to ammonia synthesis
News Publication Date:
23-Jun-2026
Web References:
http://dx.doi.org/10.1038/s41467-026-74820-4
References:
Zhujun Zhang, Shiyao Wang, Jiang Li, Masato Sasase, Masaaki Kitano, Hideo Hosono. Nature Communications. DOI: 10.1038/s41467-026-74820-4.
Image Credits:
Institute of Science Tokyo
Keywords
electrene; air-stable electride-like catalysis; ammonia synthesis; N₂ activation; oxygen doping; floating electrons; ultralow work function; ruthenium nanoparticles
