Spin-state reconfiguration of single-atom dimers via superexchange interactions enables nitrate reduction to ammonia

An electrochemical strategy for the reduction of nitrate to ammonia plays a critical role in reducing nitrate pollutants, but it faces the difficulty of multiple competing reactions and nitrate adsorption on catalyst surfaces. Different from other microstructural methods, this work focuses on spin-related electronic reconfiguration of diatomic catalysts via their superexchange interaction to regulate the bonding interaction and orbital hybridization with intermediates. The analysis of spin-related electronic structures demonstrates that the catalytic activity of single-atom dimers with a high spin state is more stable than that with a low-spin configuration. Meanwhile, the unblocked electron migration and very short interacting distances help the reactants acquire half-filled 3d-electrons more easily, leading to a lower activation energy. This work provides a new insight into the spin-related multi-electron reaction kinetics.