Co/Fe co-doped ZIF-8 derived hierarchically porous composites as high-performance electrode materials for Cu2+ ions capacitive deionization

• Published in: Chemical engineering journal (Lausanne, Switzerland : 1996) Switzerland : 1996), 2023-03, Vol.460, p.141621, Article 141621
• Main Authors: Wang, Hongyu, You, Henghui, Wu, Guoqing, Huang, Lei, Yan, Jia, Liu, Xianjie, Ma, Yuanke, Wu, Mingjie, Zeng, Yuanlin, Yu, Jianxin, Zhang, Hongguo
• Format: Article
• Language: English
• Subjects: Bimetallic co-doping; Capacitive deionization; Copper ions; Electrode material; Metal organic frameworks
• ISSN: 1385-8947; 1873-3212; 1873-3212
• DOI: 10.1016/j.cej.2023.141621

[Display omitted] •Co/Fe co-doped ZIF-8 derived porous carbon for CDI removal of Cu2+ ions.•A stable carbon cage encapsulated a porous carbon structure.•CoFe-NC has better selectivity for Cu2+ ions.•CoFe-NC shows higher electrosorption capacity in application of CDI. Due to a threat to human life from heavy metal ions pollution, unprecedented interest has been gained in the development of water purification technologies. Here, we explore another new approach to exploit a prospective carbon material for removing copper ions from aqueous solution based on rapid and easy capacitive deionization (CDI). Reasonable carbon materials modification with ideal composition and improved morphological structure is essential to additionally optimize the capabilities of CDI. We prepared a nitrogen-rich hierarchically porous carbon composites (CoFe-NC) with uniform cobalt (Co) and iron (Fe) doped metal in carbon skeleton by a simple impregnation and pyrolysis method, derived from zeolitic imidazolate framework-8, to use as highly effective CDI electrode for copper ions removal. The addition of Fe can facilitate the uniform dispersion of metals, and enable the formation of a stable carbon cage after pyrolysis. It can sufficiently expose active sites of the electrode materials and promote interfacial charge transfer, thus improving CDI electrosorption efficiency. CoFe-NC composites electrode can achieve outstanding deionization capacity (91.31 mg g−1) in 25 mg L−1 CuSO4 solution. The carbon cage structure of CoFe-NC not only prevents aggregation of metals and avoids destruction of rich multistage pore system by pyrolysis, but also induces a faster ions transport rate. In addition, density functional theory calculations demonstrated that the co-doping of Co and Fe can remarkably increase the adsorption energies of Cu2+ ions, leading to excellent selectivity, which indicates that CoFe-NC composites can be a desired CDI electrode material.