A Spin Descriptor Map Predicts NiFe2O4 for Efficient Electrosynthesis of Cyclohexanone Oxime.

The selective hydrogenation of NO to NH₂OH governs the performance of cyclohexanone oxime electrosynthesis. However, the spin state transition during the NO-to-NH₂OH process, which is directly related to reaction pathways, has long been ignored. Here, we propose a spin locking mechanism via density functional theory and sure independence screening and sparsifying operator. Magnetic sites with medium spin states stabilize the *NHO intermediate by locking the spin configuration of NO to weaken *NH₂OH adsorption for high selectivity. The spin magnetic moment (µ_S), the angle between *N-O and the catalyst (θ), and the charge state (q) are key factors, providing a screening range of the predictive metrics (µ_S·θ)³ and (cos θ/q). The theoretically selected NiFe₂O₄ delivers 70% Faradaic efficiency for cyclohexanone oxime, and weakened *NH₂OH adsorption is revealed by in situ spectroscopy. This work highlights the importance of spin regulation in adjusting the selectivity of electrosynthesis.