Controlled synthesis of bismuth oxychloride-carbon nanofiber hybrid materials as highly efficient electrodes for rocking-chair capacitive deionization

•BiOCl anchored carbon nanofibers (BiOCl-CNF) were fabricated via electrospinning.•BiOCl-CNF was used as electrode for Rocking-chair capacitive deionization (RCDI).•The synergistic effect improves both the conductivity and stability of BiOCl-CNF.•The BiOCl-CNF-based RCDI shows an ultra-high desalination rate of 0.52 mg‧g−1‧s−1.•The BiOCl-CNF-based RCDI shows excellent cycling stability and energy efficiency. Rocking-chair Capacitive Deionization (RCDI) is one of the most promising cell architectures for highly efficient capacitive deionization (CDI) to address the fresh-water shortage, and developing Cl−-removal electrode materials of RCDI toward highly-efficient desalination (with high capacity and rate) is of utmost urgency. Herein we report our design on high-performance Cl−-removal electrode material via controllable anchoring of bismuth oxychloride nanostructures (BiOCl; such as nanoplates, nanoflowers, and nanospheres) on electrospun carbon nanofibers (BiOCl-CNF) for RCDI. The BiOCl-CNF based RCDI system displays excellent Cl− storage capacitance as well as freestanding characteristics, which enables it to be a perfect electrode candidate for RCDI. By properly tailoring the composition of the hybrid material, the BiOCl-CNF based RCDI displays outstanding desalination efficacy in terms of desalination capacity (124 mg∙g−1), energy consumption (66.8 Wh∙m−3), and desalination rate (0.52 mg‧g−1‧s−1), which are far more superior than the existing systems from the literatures, exemplifying the critical importance of delicate design in the Cl−-removal electrode materials for improving the desalination performance.