Dual‐Phased Molybdenum Carbides Confined in MOF‐Derived Carbon Nanoframes Enhance Capacitive Desalination

The rational design of advanced materials with precisely engineered nanostructures presents significant challenges for water desalination technologies. Herein, dual‐phase molybdenum carbide nanoframes are fabricated through an MOF‐on‐MOF strategy, followed by controlled MoO 4 2− incorporation and pyrolysis. The resulting architecture features ultrafine MoC/Mo 2 C nanocrystals uniformly confined within conductive Co/N‐doped carbon nanoframes (MoC/Mo 2 C/CoNC), which synergistically enhances structural stability while facilitating charge transfer and ion adsorption kinetics. The MoC/Mo 2 C/CoNC exhibits a large salt adsorption capacity, low energy consumption, and high cycling stability. In situ/ ex situ characterizations combined with density functional theory calculations reveal that reversible Na + adsorption/desorption is facilitated by dynamic phase transformation between MoC and Mo 2 C, while heterointerface‐induced charge redistribution generates built‐in electric fields that significantly enhance charge transfer kinetics. This study not only establishes a new strategy for designing MOF‐derived functional materials but also provides insights into phase‐engineered heterostructures for energy‐efficient water desalination technologies.