Boosting ammonia synthesis over MoO2 by Li intercalation

Abstract

In nature, biological N₂ fixation is accessed by the nitrogenase-containing FeMo-cofactor under ambient conditions. Unfortunately, due to Brønsted–Evans–Polanyi relations, the strong Mo–N bond restricts the development of efficient Mo-based artificial catalysts for ammonia synthesis. Here, we show how to overcome this limitation by intercalating Li⁺ into layered MoO₂ materials. The intercalation of Li⁺ and balanced electrons results in the downshift of the d-band center of MoO₂, which markedly decreases the N binding energy and facilitates NH₃ generation at much lower temperatures. The introduction of Fe further promotes the massive intercalation of Li⁺ and leads to the exfoliation of bulk MoO₂ into ultrathin nanosheets. Distinctively, Li-intercalated-MoO_2−x nanosheets significantly reduce the apparent activation energy and trigger efficient and stable ammonia synthesis. This concept provides fresh insights into catalyst design for ammonia synthesis and beyond.