Docked ions: Vertical-aligned tubular arrays for highly efficient capacitive deionization

Capacitive deionization (CDI) is an effective method for desalination of brackish water to alleviate the global freshwater crisis. Obtaining high capacity primary focus this field. Based on capacitive and pseudocapacitive behavior electrodes, current research mainly devoted increasing specific surface area electrode materials, however, NaCl adsorption typically limited range 10–20 mg g−1. In work, we propose a new design paradigm using vertical-aligned nanotubular structure CDI. This allows ions be temporarily held inside electrodes like ships docked in harbor (ion-docking effect, IDE) due greatly diminished flow tubes, thus enhancing capacity. As result, obtained CDI device based P-TiO2 arrays shows ultra-high ~60 g−1 within 30 min 0.01 mol L−1 solution under 1.2 V, corresponding rapid average rate 2 min−1. Moreover, could further increased up 121 136 1.5 V 2.5 h adsorption, respectively, but still far from its equilibrium value. Finally, experiments theoretical simulations are combined understand IDE work highlights discovery utilization CDI, provides guidance can facilitate development technology.