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

Abstract

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 MoO42− incorporation and pyrolysis. The resulting architecture features ultrafine MoC/Mo2C nanocrystals uniformly confined within conductive Co/N-doped carbon nanoframes (MoC/Mo2C/CoNC), which synergistically enhances structural stability while facilitating charge transfer and ion adsorption kinetics. The MoC/Mo2C/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 Mo2C, 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.