Delocalized π-electron polymeric nanoflowers with dual redox functionalities for high-capacity and ultrafast...

The remediation of radioactive wastewater containing hazardous Sr(II) is critical for environmental safety and public health, driving demand for efficient water purification technologies. Capacitive deionization (CDI) has emerged as a promising electrochemical strategy for ion removal; however, its efficiency in capturing Sr²⁺ remains limited by the scarcity of suitable high-performance electrode materials. Herein, we develop a polymeric nanoflower material, Poly-Triphenylene-Tetracarboxyl-Perylene (PTTP), with an intrinsically delocalized electronic structure for use as an advanced CDI electrode to electrochemically capture Sr²⁺. The unique nanoflower architecture not only enhances Sr²⁺ permeability and diffusion but also, in synergy with its π-electron-rich stabilized backbone, facilitates extended electron delocalization across the polymer framework. Besides, the deliberate introduction of carbonyl and imine functionalities provides electronically optimized binding sites for Sr²⁺ uptake, as verified by in-situ characterizations, theoretical calculations, and molecular dynamics simulations. When implemented in a CDI cell, the PTTP electrode delivers an outstanding Sr²⁺ removal capacity of 48.2 mg g^-1, a rapid rate of 3.1 mg g^-1 min^-1, and long-term stability with ∼98.9% retention at 1.2 V. This exceptional CDI performance highlights the promise of PTTP for treating radioactive effluents.