Leveraging Soft Acid-Base Interactions Alters the Pathway for Electrochemical Nitrogen Oxidation to Nitrate with High Faradaic Efficiency.

Electrocatalytic nitrogen oxidation reaction (NOR) offers a sustainable alternative to the conventional methods such as the Haber-Bosch and Ostwald oxidation processes for converting nitrogen (N) into high-value-added nitrate (NO ) under mild conditions. However, the concurrent oxygen evolution reaction (OER) and inefficient N absorption/activation led to slow NOR kinetics, resulting in low Faradaic efficiencies and NO yield rates. This study explored oxygen-vacancy induced tin oxide (SnO-O) as an efficient NOR electrocatalyst, achieving an impressive Faradaic efficiency (FE) of 54.2% and a notable NO yield rate (22.05 µg h mg ) at 1.7 V versus reversible hydrogen electrode (RHE) in 0.1 m NaSO. Experimental results indicate that SnO-O possesses substantially more oxygen vacancies than SnO, correlating with enhanced NOR performance. Computational findings suggest that the superior performance of SnO-O at a relatively low overpotential is due to reduced thermodynamic barrier for the oxidation of *N to *NOH during the rate-determining step, making this step energetically favorable than the oxygen adsorption step for OER. This work demonstrates the feasibility of ambient nitrate synthesis on the soft acidic Sn active site and introduces a new approach for rational catalyst design.