Schottky Barrier‐Induced Surface Electric Field Boosts Universal Reduction of NOx− in Water to Ammonia.

NOx− reduction acts a pivotal part in sustaining globally balanced nitrogen cycle and restoring ecological environment, ammonia (NH3) is an excellent energy carrier and the most valuable product among all the products of NOx− reduction reaction, the selectivity of which is far from satisfaction due to the intrinsic complexity of multiple‐electron NOx−‐to‐NH3 process. Here, we utilize the Schottky barrier‐induced surface electric field, by the construction of high density of electron‐deficient Ni nanoparticles inside nitrogen‐rich carbons, to facilitate the enrichment and fixation of all NOx− anions on the electrode surface, including NO3− and NO2−, and thus ensure the final selectivity to NH3. Both theoretical and experimental results demonstrate that NOx− anions were continuously captured by the electrode with largely enhanced surface electric field, providing excellent Faradaic efficiency of 99 % from both electrocatalytic NO3− and NO2− reduction. Remarkably, the NH3 yield rate could reach the maximum of 25.1 mg h−1 cm−2 in electrocatalytic NO2− reduction reaction, outperforming the maximum in the literature by a factor of 6.3 in neutral solution. With the universality of our electrocatalyst, all sorts of available electrolytes containing NOx− pollutants, including seawater or wastewater, could be directly used for ammonia production in potential through sustainable electrochemical technology. [ABSTRACT FROM AUTHOR]