Boosting Active-Site Utilization in Organic Electrodes for Desalination via Side-Chain Engineering

Conventional organic small-molecule electrodes typically exhibit suboptimal utilization of their inherent electrochemically active sites (<100%) during reversible ion insertion/extraction owing to steric hindrance and structural instability. This study overcomes this limitation via functional side chain modification, expanding the molecular conformation, and integrating atoms for synergistic coordination. As demonstrated using bis(5-methylbenzothiazolyl)-naphthalene diimide (B5NDI), functionalized conjugated side chains significantly increase the intramolecular carbonyl (C=O) spacing and bolster framework stability. Crucially, the electronegative N and S atoms within the side chains cooperatively assist the C=O groups in coordinating cations. This synergistic interaction achieves the unprecedented full utilization (100%) of the carbonyl active sites, considerably exceeding the approximately 50% typical of conventional materials, highlighting its potential for high-capacity ion extraction in desalination. These findings establish engineered functional side chains as a viable strategy for markedly enhancing active-site utilization in organic electrode materials, thereby enabling advanced, ultrahigh-capacity ion capture systems.