Vacancy assisted spin-state modulation strategy for efficient nitrate electrosynthesis

Electrochemical nitrogen oxidation reaction (NOR) driven by renewable energy (RE) offers a promising alternative to traditional fossil-fuel-based thermochemical nitrate production. However, achieving efficient RE/NOR remains challenging due to the inert nature of N=N bonds and the competing oxygen evolution reaction (OER). In this study, we present a novel oxygen-vacancy-rich Ru-doped SnO₂ catalyst (Vo–RuSnOₓ) that addresses these challenges via spin polarization (SP) modulation. Lattice Ru atoms generate asymmetric bonding/antibonding 4d orbitals near the Fermi level, while adjacent oxygen vacancies supply unpaired electrons, synergistically enhancing NOR activity and suppressing OER. Density functional theory calculations reveal that the “Ru + Vo” lowers the energy barrier for *O formation and promotes the *ONN → *ONNO transition step, a critical bottleneck in NOR. Consequently, Vo–RuSnOₓ achieves a remarkable nitrate yield rate of 66.11 μg h⁻¹ mg_cat⁻¹ at 1.80 V vs RHE and a Faradaic efficiency of 23.56% at 1.60 V, surpassing the performance of benchmark oxide catalysts under acidic conditions. These findings highlight the potential of spin polarization modulation in OER-inactive hosts to stimulate selective and high-rate NOR. This study has devised a new material design strategy for the next-generation NOR catalysts manipulating the OER-derived intermediates. © 2026