Metal-Organic Framework-Derived Yolk-Shell Phosphides@Hollow Mesoporous Nanosphere Architecture for Capacitive Deionization.

Capacitive deionization (CDI) emerges as a promising low-energy desalination technology to address global water scarcity. However, its performance hinges on the design of advanced electrode materials. Herein, we proposed a novel strategy to prepare the yolk-shell structured transition metal phosphides/hollow mesoporous carbon spheres (HMCSs) composites (HZNP). The unique hollow interior effectively accommodates volume variation during ion intercalation/deintercalation. Meanwhile, the mesoporous carbon shell offers a high specific surface area and continuous pathways for ion diffusion, thereby synergistically improving charge transfer kinetics and structural stability. The HZNP-20-30 composite demonstrates an optimal desalination capacity of 49.6 mg g-1. This performance is attributable to its preserved ZIF framework from ion-exchange etching, which maintains chemical and structural integrity. Furthermore, the synergistic effect between the CoNi bimetallic phosphides and the N-doped mesoporous carbon shell significantly enhances the electrochemical performance. This study not only provides strong theoretical support for the confined growth of metal phosphide nanoparticles in HMCSs but also verifies the superiority of the yolk-shell structure in the application of CDI.