Electron Redistribution by Fluorine-Induced Dual Defects in Cu₃P Accelerated Charge Transfer Toward High-Performance...

Electrochemical chloride ion removal is essential for clean water and environmental protection, yet its practical application is hindered by the sluggish kinetics, especially using high-mass-loading electrodes. Conventional extrinsic modifications, such as conductive additives or structural design, exhibit constrained effectiveness. Here, we report an intrinsic enhancement strategy through heteroatom doping-induced dual defects engineering, demonstrated by the successful synthesis of fluorine-doped copper(I) phosphide with phosphorus vacancies (F-Cu₃P_V) via molten salt treatment. Based on density functional theory calculations and experimental results, F doping caused lattice distortion, generating P vacancies to form dual defects. These defects effectively modulated intrinsic electron redistribution, resulting in improved electrical conductivity, enhanced adsorption capability, and reduced chloride ion diffusion energy barriers. Therefore, electron transfer and ion diffusion kinetics were significantly accelerated, leading to superior electrochemical performance. Resultantly, the F-Cu₃P_V electrode performed exceptional electrochemical chloride ion removal performance with superior areal deionization capacity (3.16 ± 0.02 mg cm^-2) and a remarkably rapid areal deionization rate (0.106 ± 0.001 mg cm^-2 min^-1), as well as outstanding cycling stability (95.65% retention after 70 cycles). This work elucidates electron redistribution via heteroatom doping-induced dual defects as a viable pathway to overcome the intrinsic kinetic bottleneck for high-performance electrochemical chloride ion removal.