Spinel Nickel Ferrite on Metal–Organic Framework-Derived Porous Carbon as a Robust Faradaic Electrode for Enhanced Flow Capacitive Deionization
Biswajit Mishra, Swayamprakash Biswal, Bijay P. Tripathi
Abstract
Water desalination by capacitive deionization techniques has often suffered from the relegating performance of carbon-based non-Faradaic electrode materials. To overcome the rate-limiting charge transfer kinetics and weak ion adsorption tendency, a metal–organic framework (MOF)-derived hybrid electrode with an exceptional flow capacitive deionization performance is reported here. Using MIL-88(FeNi) as a sacrificial template, we synthesized a porous graphitic framework decorated with nanosized spinel NiFe 2 O 4 (NiFe 2 O 4 @PC-500) electrodes, maintaining a parent rod-shaped morphology with a large surface area of 1227 m 2 /g. The synergistic interaction of NiFe 2 O 4 nanoparticles with the mesoporous graphitic framework exhibited remarkable desalination performance with a salt adsorption capacity of ∼34 mg/g and ∼89% salt removal at 1.2 V, surpassing those of traditional carbon-based electrodes. Moreover, NiFe 2 O 4 @PC-500 maintained its desalination capacity and structural integrity over prolonged desalination cycles with a specific capacitance of ∼206 F/g and capacitive retention over 500 cycles. This study presents a universal approach for strategically implementing MOF-derived heterostructures as potent flow electrode materials.