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

Electrocatalytic nitrogen oxidation reaction (N₂OR) offers a sustainable alternative to the conventional methods such as the Haber-Bosch and Ostwald oxidation processes for converting nitrogen (N₂) into high-value-added nitrate (NO₃ ^-) under mild conditions. However, the concurrent oxygen evolution reaction (OER) and inefficient N₂ absorption/activation led to slow N₂OR kinetics, resulting in low Faradaic efficiencies and NO₃ ^- yield rates. This study explored oxygen-vacancy induced tin oxide (SnO₂-O_v) as an efficient N₂OR electrocatalyst, achieving an impressive Faradaic efficiency (FE) of 54.2% and a notable NO₃ ^- yield rate (22.05 µg h^-1 mg_cat ^-1) at 1.7 V versus reversible hydrogen electrode (RHE) in 0.1 m Na₂SO₄. Experimental results indicate that SnO₂-O_v possesses substantially more oxygen vacancies than SnO₂, correlating with enhanced N₂OR performance. Computational findings suggest that the superior performance of SnO₂-O_v at a relatively low overpotential is due to reduced thermodynamic barrier for the oxidation of *N₂ to *N₂OH 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.