Harnessing Spin-Lattice Interplay in Metal Nitrides for Efficient Ammonia Electrosynthesis

Metal nitrides, renowned for their spin-lattice-charge interplay, offer vast potential in catalysis, electronics, and energy conversion. However, spin polarization manipulation in these nitrides remains a challenge for multi-electron electrocatalytic processes. This study introduces Co₃Mo₃N with a low-spin polarization configuration, achieved by incorporating spin-free lattice Mo with 4d orbitals into high-spin polarization Co₄N. This innovation delivers outstanding nitrate-to-ammonia electrosynthesis, ranking among the best to date. Mo inclusion induces competing magnetic exchange interactions, reducing the spin polarization degree and enabling rate-determining step of NO₂* to NO-OH* conversion via vertex-sharing NMo₆ octahedra. A paired electro-refinery with a Co₃Mo₃N cathode achieves 2 000 mA cm^-2 at 2.28 V and sustains an industrial-scale current of 1 000 mA cm^-2 for 2,100 h, with an NH₃ production rate of ≈70 mg NH₃ h^-1 cm^-2. This work establishes a transformative platform for spin polarization degree-engineered electrocatalysts, driving breakthroughs in energy conversion technologies.