Multiple Sites\nOrganic Small-Molecule Electrode Material\nfor High-Capacity Seawater Desalination

Redox-active organic materials, especially small molecules,\nare\nexpected as alternatives to inorganic materials in electrochemical\nenergy storage due to their multisite and high-capacity merits. Inspired\nby this, herein, we propose an organic small molecular material 1,4,5,8-naphthalenediimide\n(NDI) with multiple ion insertion sites as an efficient electrode\nmaterial for seawater desalination. By providing a conductive and\nconfined environment through a double-layer gel encapsulation strategy,\nwe have solved the problem of dissolution and detachment of small\nmolecular materials. Benefitting from multiple sites provided by carbonyl\noxygen and the (−1–12) crystal plane, the fabricated\ncomposite electrode exhibits remarkable removal capacity for Na<sup>+</sup> (145 mg g<sup>–1</sup>) in 0.5 M NaCl solution. Furthermore,\nin natural seawater, the composite electrode demonstrates high stability\nand achieves impressive removal capacities for Na<sup>+</sup> (107\nmg g<sup>–1</sup>), Mg<sup>2+</sup> (48 mg g<sup>–1</sup>), Ca<sup>2+</sup> (12 mg g<sup>–1</sup>), and K<sup>+</sup> (9.2 mg g<sup>–1</sup>), respectively. This work has realized\nthe application of multisite small-molecule materials in seawater\ndesalination by solving the problems of dissolution and detachment\nof organic small molecules, paving the way for developing novel efficient\norganic materials in electrochemical seawater desalination.