Excess Electron-Driven p-π Backdonation Enables Boron Single-Atom Catalysis for Nitrogen Reduction in Fluorinated Fullerene Nanoreactors

Overcoming the persistent challenges in catalytic nitrogen reduction (N2R), including the inertness of N2, reliance on precious/transition metals (TMs), and inefficiency of main-group elements, requires innovative strategies. Herein, we demonstrate a metal-free cocatalysis system using fluorinated fullerene C69F69B and excess electrons (EEs) that enables efficient N2-to-NH3 conversion. This system mimics the critical d-π backdonation capability of TMs through a distinct p-π backdonation mechanism. Specifically, the confined C69F69B nanoreactor traps EEs, activating the boron (B) atom’s p-like hybrid orbital to partially populate the π*-orbital of encapsulated N2, driving spontaneous N2 coordination and N≡N bond activation. Throughout hydrogenation steps, B acts as an electron transfer hub, synergistically cooperating with EEs to stabilize intermediates and reduce the energy barrier. The rate-determining step exhibits a remarkably low barrier of 28.89 kcal/mol, competitive with state-of-the-art TM catalysts. This work elucidates a paradigm-shifting approach for activating inert small molecules via main-group elements, offering a design blueprint for high-efficiency, metal-free catalysts in multielectron reduction beyond nitrogen fixation.