Selective nitric oxide electroreduction at monodispersed transition-metal sites with atomically precise coordination environment

Mitigating nitrogen oxide emissions is critical to tackling global warm-ing and improving air quality. Electrochemically converting nitrogen oxide pollutants into value-added fuels such as ammonia (NH3) and hy-droxylamine (NH2OH) is of great significance, yet the efficiency is hin-dered by complex reaction pathways and sluggish kinetics. Here, we demonstrated monodispersed transition-metal sites, e.g., iron (Fe) and nickel (Ni), with atomically precise coordination environments to electrocatalyze nitric oxide conversion with remarkable selectivity, ac-tivity, and durability. We observed that metal centers strongly regulate the nitrogen-product distribution. In particular, Ni preferred NH3 production with a high yield rate of 1.6 mmol mg -1 h-1, whereas Fe ex-hibited a superior selectivity toward NH2OH, approaching a record -high production rate of 3.1 mmol mg -1 h-1 with a selectivity of 83.5%. Operando Fourier transform infrared spectroscopy revealed different NO adsorption capabilities of single-atomic Ni and Fe, which can well explain the different reduction pathways according to the theo-retical calculations.