Copper sulfide mineral performs non-enzymatic anaerobic ammonium oxidation through a hydrazine intermediate

Anaerobic ammonium oxidation (anammox)-the biological process that activates ammonium with nitrite-is responsible for a significant fraction of N₂ production in marine environments. Despite decades of biochemical research, however, no synthetic models capable of anammox have been identified. Here we report that a copper sulfide mineral replicates the entire biological anammox pathway catalysed by three metalloenzymes. We identified a copper-nitrosonium {CuNO}¹⁰ complex, formed by nitrite reduction, as the oxidant for ammonium oxidation that leads to heterolytic N-N bond formation from nitrite and ammonium. Similar to the biological process, N₂ production was mediated by the highly reactive intermediate hydrazine, one of the most potent reductants in nature. We also found another pathway involving N-N bond heterocoupling for the formation of hybrid N₂O, a potent greenhouse gas with a unique isotope composition. Our study represents a rare example of non-enzymatic anammox reaction that interconnects six redox states in the abiotic nitrogen cycle.