Quantifying the Triboelectric Series of Liquid Phase Materials

Contact electrification has been extensively investigated and harnessed, yet quantifying the triboelectrification capacity of liquid phase materials remains elusive due to their non-fixed shape and complex flow dynamics. Here, we report a novel gas-regulated flow strategy to stabilize liquid columns, effectively decoupling fluid kinetics from electrification processes. By optimizing material selection, electrode configurations, and flow regimes, we established a standardized triboelectric series encompassing 50 diverse liquids, including organic solvents and ionic solutions. Our results reveal that liquid-phase triboelectrification is synergistically governed by molecular functional groups, ionic species, and concentrations. Specifically, hydroxyl groups and dilute ion concentrations promote charge transfer, whereas alkyl groups and excessive ions exert a suppressive effect. This study elucidates that liquid-solid electrification arises from a sophisticated interplay of electron transfer, molecular polarization, ion adsorption/screening, which collectively dictate charge redistribution. By providing a quantitative triboelectric matrix, this work facilitates the design of high-efficiency energy harvesters and safer industrial liquid-handling systems, advancing the fundamental understanding of liquid-interface physics.