Prussian Blue/Carbon Nanofiber Amalgamated Conductive Scaffolds for Capacitive Deionization

Capacitive deionization (CDI) is an emerging technique of seawater desalination technology with high efficiency and low energy consumption. Prussian blue (PB) is considered to be an excellent candidate for CDI intercalation electrode materials due to its spacious three-dimensional ion diffusion channels and available low-cost raw materials. However, the agglomerate tendency and inferior electronic conductivity of PB are the main factors which lead to lower capacity and poor cycling stability. Herein, a Prussian blue nanoparticle/carbon nanofiber (PB/CNF) composite material was synthesized by electrospinning and coprecipitation for capacitive deionization. The conductive CNFs bridged the PB nanoparticles with a size of ca. 50 nm to form a 3D conductive network structure, which can boost the diffusion kinetics of salt ions and electrons simultaneously in the PB/CNF electrode. The ion storage process by the combination of capacitance-controlled and diffusion-controlled behaviors allows the PB/CNF-5 composite to achieve a salt adsorption capacity (SAC) of 51.81 mg g–1 in a 500 mg L–1 NaCl solution at 1.4 V, and it has excellent cycle stability for 80 cycles. Remarkably, it also shows an excellent salt adsorption performance of 97.35 mg g–1 in a 3000 mg L–1 NaCl solution. Overall, the strategy of antiaggregation and enhanced electronic conductivity not only improved the desalination performance of PB nanoparticles but also provided a technical guideline for nanometer-sized materials and helped to facilitate better CDI electrode design.