A new nitrogen fixation strategy: the direct formation of N 2 − excited state on metal-free photocatalyst

N 2 fixation under mild conditions using renewable electricity or solar energy is a promising alternative to the century-old Haber–Bosch process; however, it is generally impeded by the initial hydrogenation and competitive hydrogen evolution reaction. Herein, a new N 2 fixation strategy is proposed via directly forming *N 2 − excited state on metal-free boron-decorated diamond clusters (BDCs). Surface-doped B atoms facilitate the adsorption of N 2 and simultaneously suppress H + due to the repulsion of Lewis acids. Excited state dynamics simulations demonstrate that valence electrons using the valence-band edge of BDCs as springboard are directly excited into the π* orbitals of *N 2 under the illumination of ∼4 eV light (far below ∼11 eV for free N 2 ), which not only further improves the selectivity but also forms activated *N 2 − excited states with sufficient lifetime (∼10 ns) for the initial hydrogenation. This work affords fresh insight to advance photocatalysis for sustainable NH 3 production.