Highly selective electrochemical nitrate reduction using copper phosphide self-supported copper foam electrode: Performance, mechanism, and application. (1st April 2021)

• Record Type: Journal Article
• Authors: Yao, Fubing; Jia, Maocong; Yang, Qi; Chen, Fei; Zhong, Yu; Chen, Shengjie; He, Li; Pi, Zhoujie; Hou, Kunjie; Wang, Dongbo; Li, Xiaoming
• Is Part Of: Water research. Volume 193(2021)
• Publication Date: 2021-04-01
• Subjects: Binder-free electrode -- Copper foam -- Copper phosphide -- Electrochemical denitrification -- Reaction mechanism; Water -- Pollution -- Research -- Periodicals; 363.7394
• DOI: 10.1016/j.watres.2021.116881
• Languages: English
• ISSNs: 0043-1354

Abstract

Highlights: A binder-free composite electrode (Cu3 P/CF) was prepared by Cu3 P directly growing on Cu foam. The Cu3 P/CF showed high activity and selectivity for electrochemical denitrification. Electrochemical NO3 − reduction was achieved via the redox reaction of Cu 0 /NO3 − . Cu3 P was a bifunctional electrocatalyst for electron transfer and NO2 − conversion. A 2-stage process (per-oxidation and post-reduction) was designed for real wastewater treatment. Abstract: A highly active and selective electrode is essential in electrochemical denitrification. Although the emerging Cu-based electrode has attracted intensive attentions in electrochemical NO3 − reduction, the issues such as restricted activity and selectivity are still unresolved. In our work, a binder-free composite electrode (Cu3 P/CF) was first prepared by direct growth of copper phosphide on copper foam and then applied to electrochemical NO3 − reduction. The resulting Cu3 P/CF electrode showed enhanced electrochemical performance for NO3 − reduction (84.3%) with high N2 selectivity (98.01%) under the initial conditions of 1500 mg L −1 Cl − and 50 mg N L −1 NO3 − . The cyclic voltammetry (CV) and electrochemical impedance spectra (EIS) demonstrated that electrochemical NO3 − reduction was achieved through electron transfer between NO3 − and Cu 0 originated from CF. The in-situ grown Cu3 P served as the bifunctional catalyst, the electron mediator or bridge to facilitate the electron-transfer for NO3 − reduction and the stable catalyst to produce atomic H* toward NO2 − conversion. Meanwhile, the Cu3 P/CF remained its electrocatalytic activity even after eight cyclic experiments. Finally, a 2-stage treatment strategy, pre-oxidation by Ir-Ru/Ti anode and post-reduction by Cu3 P/CF cathode, was designed for electrochemical chemical oxygen demand (COD) and total nitrogen (TN) removal from real wastewater. Graphical abstract: Image, graphical abstract