Research

2026.09.25　Making ammonia at lower temperatures: the world's first air-stable surface electrene

A research team led by Hideo Hosono, Honorary and Institute Professor at Institute of Science Tokyo (Science Tokyo), has now demonstrated the world’s first air-stable surface electrene, using barium silicon nitride (BaSiN₂) containing a small amount of oxygen. The material overcomes one of the major limitations of previous electrenes: their instability in air. The researchers confirmed that its crystal structure remained intact even after one week of exposure to air.

What makes the surface electrene particularly intriguing is the way its surface changes during a reaction. When the electrons floating at the surface are transferred to nitrogen molecules, the nitrogen molecules remain on the surface, temporarily stabilizing it. When hydrogen is then introduced, the nitrogen is converted into ammonia and leaves the surface, allowing electrons to reappear.

In other words, nitrogen protects the surface, and once the reaction proceeds, the surface returns to a state in which it can once again supply electrons.

The researchers also combined the material with ruthenium (Ru) and showed that it could efficiently catalyze ammonia production at lower temperatures and pressures than conventional approaches. Its catalytic performance was maintained even after repeated exposure to air.

A closer look at the reaction mechanism revealed that ammonia could be produced even at 30°C. The researchers also confirmed that the floating surface electrons make nitrogen molecules more reactive—a distinctive feature of this material.

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