Perovskite oxide LaMO3-δ (M = Fe, Co, Ni and Cu) cathode for efficient electroreduction of nitrate

• Published in: Separation and purification technology 2022-08, Vol.295, p.121278, Article 121278
• Main Authors: Yang, Wen-Jian, Yang, Li-Hui, Peng, Han-Jun, Lv, Si-Hao, Muhammad Adeel Sharif, Hafiz, Sun, Wei, Li, Wei, Yang, Cao, Lin, Hui
• Format: Article
• Language: English
• Subjects: Cu(I)-Cu(II) couple; La2CuO4; NO3–-N electroreduction; Perovskite oxide; Selectivity
• ISSN: 1383-5866; 1873-3794
• DOI: 10.1016/j.seppur.2022.121278

[Display omitted] •Perovskite oxide LaMO3-δ cathodes were applied for NO3–-N electroreduction.•La2CuO4 exhibited best catalytic performance as its super electrochemical property.•The selectivity of NH4+-N and N2 were 82.4 ± 2.2% and 9.4 ± 2.4%, respectively.•Both electron- and H*-mediated pathway occurred for NO3–-N electroreduction.•Oxygen vacancies and redox cycle of Cu(I)-Cu(II)-Cu(I) worked for NO3–-N reduction. Electroreduction removal of nitrate (NO3–-N) is considered as a promising approach to solve its adverse effects on environment and human health, where efficient and cheap catalysts are required. Perovskite-based catalysts showed a versatile catalytic ability for wide range of redox reactions, but seldom applied for NO3–-N reduction. Herein, four perovskite oxide cathodes, LaMO3-δ (M = Fe, Co, Ni and Cu) were prepared and used for the reduction of NO3–-N. The Ruddlesden-Popper (RP) type La2CuO4 exhibited the best NO3–-N catalytic activity among the four perovskite oxide cathodes, with a removal rate of 11.7 × 10-3 min−1. The high selectivity of NH4+-N (82.4 ± 2.2%) indicated that NH4+-N was the main final product for NO3–-N electroreduction at La2CuO4 cathode, but 100% of N2 selectivity could be obtained with addition of 1000 and 1500 mg/L Cl- as the electro-assisted chlorination process. The mechanism of NO3–-N electroreduction occurred by both electron- and H*-mediated pathway, and the oxygen vacancies and redox cycle of Cu(I)-Cu(II)-Cu(I) were proposed as the accommodation sties and direct electron sources for NO3–-N reduction. Generally, this study opens a novel avenue for the development of earth-abundant, cost-effective catalyst with effective NO3–-N electroreduction.