Perovskite Oxide as A New Platform for Efficient Electrocatalytic Nitrogen Oxidation.

Electrocatalytic nitrogen oxidation reaction (NOR) offers an efficient and sustainable approach for conversion of widespread nitrogen (N ₂ ) into high-value-added nitrate (NO ₃ ^- ) under mild conditions, representing a promising alternative to the traditional approach that involves harsh Haber-Bosch and Ostwald oxidation processes. Unfortunately, due to the weak absorption/activation of N ₂ and the competitive oxygen evolution reaction, the kinetics of NOR process is extremely sluggish accompanied with low Faradaic efficiencies and NO ₃ ^- yield rates. In this work, an oxygen-vacancy-enriched perovskite oxide with nonstoichiometric ratio of strontium and ruthenium (denoted as Sr _0.9 RuO ₃ ) was synthesized and explored as NOR electrocatalyst, which can exhibit a high Faradaic efficiency (38.6 %) with a high NO ₃ ^- yield rate (17.9 μmol mg ^-1  h ^-1 ). The experimental results show that the amount of oxygen vacancies in Sr _0.9 RuO ₃ is greatly higher than that of SrRuO ₃ , following the same trend as their NOR performance. Theoretical simulations unravel that the presence of oxygen vacancies in the Sr _0.9 RuO ₃ can render a decreased thermodynamic barrier toward the oxidation of *N ₂ to *N ₂ OH at the rate-determining step, leading to its enhanced NOR performance.
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