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 NO x - anions on the electrode surface, including NO 3 - and NO 2 - , and thus ensure the final selectivity to NH 3 . Both theoretical and experimental results demonstrate that NO x - anions were continuously captured by the electrode with largely enhanced surface electric field, providing excellent Faradaic efficiency of 99 % from both electrocatalytic NO 3 - and NO 2 - reduction. Remarkably, the NH 3 yield rate could reach the maximum of 25.1 mg h -1 cm -2 in electrocatalytic NO 2 - 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 NO x - pollutants, including seawater or waste water, could be directly used for ammonia production in potential through sustainable electrochemical technology.