A potential-driven NiO/NiCo LDH film electrode for highly efficient extraction of Br- via electrochemical coordination and anion exchange

• Published in: Chemical engineering journal (Lausanne, Switzerland : 1996) Switzerland : 1996), 2023-11, Vol.475, p.146345, Article 146345
• Main Authors: Gao, Fengfeng, Jiang, Mengfang, Hao, Xiaogang, Li, Jun, Liu, Zhong, Ji, Zhiyong
• Format: Article
• Language: English
• Subjects: Anion exchange; Br− ions extraction; Electrochemical coordination; Electrochemically switched ion exchange; NiO/NiCo LDH composite film
• ISSN: 1385-8947; 1873-3212
• DOI: 10.1016/j.cej.2023.146345

[Display omitted] •A NiCo LDH/NiO film was successfully prepared for Br− extraction.•Electrochemical coordination and anion exchange mechanism was proposed.•The Br− extraction capacity of NiCo LDH/NiO film was as high as159.25 mg·g−1.•The NiCo LDH/NiO film showed superior electrochemical stability. A potential-driven nickel oxide/NiCo layered double hydroxide (NiO/NiCo LDH) composite film was deposited within the stainless steel wire mesh, showing excellent Br− extraction in an electrochemically switched ion exchange (ESIX) system. In this composite film, NiO with a high specific surface area and porous structure served as the lower layer to improve the electrical conductivity and ion storage capacity of the film, while NiCo LDH served as the main selective separation layer to selectively adsorb the target Br−. The film electrode extracted Br− up to 159.25 mg·g−1 and the separation factors of Br−/Cl−, Br−/NO3−, and Br−/I− were 2.04, 8.89, and 5.45, respectively. The film electrode showed excellent adsorption–desorption cyclability and electrochemical stability since the NiO increased the binding force and electrical conductivity between NiCo LDH and substrate, and its porous structure accommodated Br−. The highly efficient extraction of Br− in neutral solution was attributed to the electrochemical coordination and interlayer anion exchange sites of NiO/NiCo LDH. This study provided a deep understanding of the ion selective extraction mechanism of LDH-based materials by ESIX technology and the novel electrochemical reaction design of electrodes, which could be used in other fields such as supercapacitors, sensors, and batteries.