Solute‐Engineered Functional Liquids Surpassing Deionized Water for High‐Performance Liquid–Solid Triboelectrification

Liquid–solid (L–S) triboelectrification underpins emerging droplet‐based triboelectric sensors (L–S TESs), which offer high sensitivity and rapid response; however, harnessing their full potential requires a nuanced understanding of how solute‐solvent interactions at the liquid–solid interface govern charge transfer. This study systematically investigates the impact of distinct solute chemistries—encompassing strong hydrogen‐bonding polyols (D‐sorbitol, D‐glucose, and D‐sucrose) and ethers (diethyl ether (DEE) and tetrahydrofuran (THF)), on the triboelectrification of aqueous droplets at a PTFE interface. Crucially, we demonstrate that low‐concentration DEE (0.1 wt%) increases the saturated transferred charge ( Q SC − sat ) by approximately 30% relative to DI water under identical device and operating conditions. This enhancement is accompanied by favorable interfacial‐tension modification and is proposed to arise from an increased availability of interfacial water for electron transfer. In contrast, high‐concentration sucrose, a strong hydrogen‐bonder, not only substantially impedes charge transfer but also uniquely induces a time‐dependent charge decay. By correlating four key electrical output characteristics (including initial charge rate ( R 0 ) and Q SC − sat ) with solution physicochemical properties, we elucidate the distinct roles of solute structure, concentration, and intermolecular forces. These findings clarify how solute chemistry and concentration influence charge accumulation in aqueous L–S TESs and provide a basis for tuning their electrical response through liquid composition.