Integrating Ozone Pollutant Elimination in N 2 Electrolysis to Produce Nitrate with Reduced Reaction Steps.

The synthesis of nitrate by the electrochemical N 2 oxidation reaction (NOR) is currently one of the most promising routes. However, the traditional generation of nitrate depends on the oxidation reaction between N 2 and H 2 O (or ·OH), which involves complex reaction steps and intermediates, showing strong competition from oxygen evolution reaction (OER). Here, an effective NOR method is proposed to directly oxidize N 2 by using O 3 as a reactive oxygen source to reduce the reaction step. Electrochemical tests demonstrate that the nitrate yield of Pd-Mn 3 O 4 /CNT electrocatalyst reaches the milligram level, which is the highest yield reported so far for electrocatalytic NOR. Quantitative characterization is employed to establish a comprehensive set of benchmarks to confirm the intrinsic nature of nitrogen activation and test the O 3 -mediated reaction mechanism. Density functional theory (DFT) calculations show that the heterostructure Pd-Mn 3 O 4 leads to a strong adsorption preference for N 2 and O 3 , which greatly reduces the activation energy barrier for N 2 . This accelerates the synthesis of nitrate based on the direct formation mechanism, which reduces energy barriers and the reaction steps, thus increasing the performance of electrocatalytic nitrate production. The techno-economic analysis underscores the promising feasibility and sustainable economic value of the presented method.