Constructing built-in electric field via CuO/NiO heterojunction for electrocatalytic reduction of nitrate at low concentrations to ammonia

• Published in: Chinese chemical letters Vol. 35; no. 12; pp. 109789 - 326
• Main Authors: Chen, Ying, Xia, Xingyuan, Tian, Lei, Yin, Mengying, Zheng, Ling-Ling, Fu, Qian, Wu, Daishe, Zou, Jian-Ping
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 01.12.2024; Key Laboratory of Poyang Lake Environment and Resource Utilization,Ministry of Education,School of Resources & Environment,Nanchang University,Nanchang 330031,China; National-Local Joint Engineering Research Center of Heavy Metals Pollutants Control and Resource Utilization,School of Environmental and Chemical Engineering,Nanchang Hangkong University,Nanchang 330063,China%National-Local Joint Engineering Research Center of Heavy Metals Pollutants Control and Resource Utilization,School of Environmental and Chemical Engineering,Nanchang Hangkong University,Nanchang 330063,China%Key Laboratory of Poyang Lake Environment and Resource Utilization,Ministry of Education,School of Resources & Environment,Nanchang University,Nanchang 330031,China; School of Materials and Chemical Engineering,Pingxiang University,Pingxiang 337000,China
• Subjects: Built-in electric field; Electrocatalytic reduction of NO3; Low concentrations; NH4+ selectivity; H; Built-in electric field; Low concentrations; NH4+ selectivity; Electrocatalytic reduction of NO3; NH4+selectivity
• ISSN: 1001-8417
• DOI: 10.1016/j.cclet.2024.109789

Electrocatalytic reduction of nitrate (NO3−) at low concentrations to ammonia (NH4+) still faces challenges of low NO3− conversion and NH4+ selectivity due to the sluggish mass transfer and insufficient atomic hydrogen (H*) supply. Herein, we propose CuO/NiO heterojunction with the assistance of a built-in electric field to enhance mass transfer and H* provision. The built-in electric field in CuO/NiO is successfully formed as demonstrated by X-ray photoelectron spectroscopy and ultraviolet photoemission spectroscopy. The results reveal that CuO/NiO achieves high NO3− reduction activity (100%) and NH4+ selectivity (100%) under low NO3− concentration conditions (100 mg/L NO3−, ca. 22.6 mg/L NO3−-N), which is superior to that of many recently reported electrocatalysts. Density functional theory calculations further clarify that the built-in electric field triggers the enhanced adsorption of reactants on CuO/NiO heterojunction interface and strong d-p orbital hybridization between reactants and CuO/NiO. Besides, the free energy diagram of hydrogen evolution reaction of CuO/NiO confirms the realization of enhanced H* provision. Moreover, coupling experiments and consecutive cycle tests demonstrate the potential of CuO/NiO in practical applications. This work may open up a new path and guide the development of efficient electrocatalysts for electrocatalytic reduction of NO3− at low concentrations to NH4+. CuO/NiO heterojunction with the assistance of a built-in electric field enhances the mass transfer of low concentration reactants and H* provision, thus achieving efficient electrocatalytic reduction of NO3− at low concentrations to NH4+. [Display omitted]