Ambient nitrogen reduction cycle using a hybrid inorganic–biological system

Significance The nitrogen cycle and the fixation of atmospheric N 2 into ammonium are crucial to global food production. The industrial Haber–Bosch process facilitates half the global nitrogen fixation in the form of ammonia but it is energy- and resource-intensive, using natural gas as the source of energy and hydrogen at elevated temperature and pressure. Our alternative approach synthesizes ammonium from N 2 and H 2 O at ambient conditions powered by water splitting, which may be driven renewably. The inorganic–biological hybrid system fixes atmospheric nitrogen into NH 3 or soluble biomass with high fluxes and energy efficiency. Simultaneously, this system cultivates a living soil bacterium that acts as a potent biofertilizer amenable to boosting crop yields.