Boron phosphide as an efficient metal-free catalyst for nitrate electroreduction to ammonia

Boron phosphide (BP) is first explored as an efficient metal-free catalyst towards the NO3RR, delivering the highest NH3-faradaic efficiency of 96.3% with a corresponding NH3 yield rate of 3.1 mg h-1 cm-2, outperforming most reported metal-based NO3RR catalysts. Theoretical calculations unravel that active B centers not only enable the efficient NO3- activation and hydrogenation with a low energy barrier, but also preferentially absorb NO3- over H adatoms to prohibit the competing hydrogen evolution, enhancing both NO3RR activity and selectivity.