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

• Published in: Angewandte Chemie International Edition Vol. 60; no. 38; pp. 20711 - 20716
• Main Authors: Gao, Peng, Xue, Zhong‐Hua, Zhang, Shi‐Nan, Xu, Dong, Zhai, Guang‐Yao, Li, Qi‐Yuan, Chen, Jie‐Sheng, Li, Xin‐Hao
• Format: Journal Article
• Language: English
• Published: Weinheim Wiley Subscription Services, Inc 13.09.2021
• Edition: International ed. in English
• Subjects: Ammonia; Anions; Chemical reduction; Electric fields; Electrocatalysts; Electrochemistry; Electrodes; Electrolytes; heterogeneous catalysis; Nanoparticles; Nitrogen cycle; Nitrogen dioxide; Nitrogen oxides; NOx− removal; Pollutants; Schottky barrier; Seawater; Selectivity; sulfur-diffusion; surface electric field; Wastewater; Wastewater pollution
• ISSN: 1433-7851; 1521-3773
• DOI: 10.1002/anie.202107858

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. The tunable surface electric field induced by Schottky barrier boosts the reduction of NOx− in water for ammonia production. The tunable amounts of Ni nanoparticles inside a nitrogen‐rich carbon support could gradually enhance the surface electric field for enriching and fixation of NOx− anions, achieving a high Faradaic efficiency of 99 % for ammonia production from both electrocatalytic NO3− and NO2− reduction.