Directional Ion Transport Through Nanoarchitected 1D Mesochannels: 2D Polymer Interfacial Engineering for High-Efficiency Capacitive Deionization.

The development of high-performance capacitive deionization (CDI) electrodes demands innovative materials that integrate rapid ion transport, high salt adsorption capacity (SAC), and oxidative stability. This challenge is addressed through a surface nanoarchitectonics strategy, constructing 2D mesochannel polypyrrole/reduced graphene oxide heterostructures (mPPy/rGO) with ordered 1D mesochannels (~8 nm) parallel to the graphene surface. By confining the self-assembly of cylindrical polymer brushes on freestanding rGO substrates, directional ion highways are simultaneously engineered that significantly reduce transport tortuosity. In addition, corrosion-resistant polymer interfaces block oxygen penetration, and strong interfacial interactions between PPy and rGO ensure efficient electron transfer. The mPPy/rGO-based CDI cell achieves breakthrough performance: ultrahigh SAC of 84.1 mg g (4.5× activated carbon, the salt concentration: 2 g L), and 96.8% capacity retention over 100 cycles in air-equilibrated saline solution (the salt concentration: 500 mg L). This interfacial confinement methodology establishes a universal paradigm for designing polymer-based desalination materials with atomically precise transport pathways.