Boosting ammonia synthesis over MoO₂ by Li intercalation

In nature, biological N-2 fixation is accessed by the nitrogenase-containing FeMo-cofactor under ambient conditions. Unfortunately, due to Bronsted-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-MoO2-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.