Making ammonia from nitrogen and water microdroplets

Water (H(2)O) microdroplets are sprayed onto a magnetic iron oxide (Fe(3)O(4)) and Nafion-coated graphite mesh using compressed N(2) or air as the nebulizing gas. The resulting splash of microdroplets enters a mass spectrometer and is found to contain ammonia (NH(3)). This gas–liquid–solid heterogeneous catalytic system synthesizes ammonia in 0.2 ms. The conversion rate reaches 32.9 ± 1.38 nmol s(−1) cm(−2) at room temperature without application of an external electric potential and without irradiation. Water microdroplets are the hydrogen source for N(2) in contact with Fe(3)O(4). Hydrazine (H(2)NNH(2)) is also observed as a by-product and is suspected to be an intermediate in the formation of ammonia. This one-step nitrogen-fixation strategy to produce ammonia is eco-friendly and low cost, which converts widely available starting materials into a value-added product.