Flexible 3D interlocking electron/ion transport NaTi₂(PO₄)₃@C nanofibers for high-performance capacitive deionization

NaTi₂(PO₄)₃ (NTP) has open three-dimensional (3D) ion channels and a high theoretical capacity, but its inherent low electronic conductivity and poor structural stability impede practical applications. Meanwhile, the desalination mechanism of NTP in capacitive deionization (CDI) remains unclear, and the form of ion intercalation conversion is still ambiguous. Herein, we present an electron/ion transport-enhanced strategy for fabricating self-supporting electrodes via constructing an interlaced 3D network, which establishes interconnected channels for rapid electron/ion transfer and diffusion while simultaneously enhancing structural durability and mechanical robustness. The NTP combined with carbon nanofibers (NTP/CNF) composite electrode exhibits excellent salt adsorption capacity (83.9 mg·g⁻¹), fast salt adsorption rate (7.5 mg·g⁻¹·min⁻¹), and cycling stability. Furthermore, the desalination mechanism of the NTP/CNF electrode during the CDI process was revealed through ex-situ X-ray diffraction (XRD) patterns, Raman spectra, and X-ray photoelectron spectroscopy (XPS) spectra, clarifying the transition from a sodium-deficient phase (NaTi₂(PO₄)₃) to a sodium-rich phase (Na₃Ti₂(PO₄)₃).