Ultra-High Contact Electrified Current Generation and Chemical Sensing at IL-Based Immiscible Liquid–Liquid Interface

Though the charge transfer efficiency of a liquid–liquid (L-L) nanogenerator is much higher than that of the solid–liquid and solid–solid counterparts, there is still much room for improving the level of interfacial charge transfer. In this study, a power generation system was designed using an ionic liquid (IL)-based immiscible L-L interface via the contact/separation mode. The maximum output electric current reaches as high as about 8.12 μA by contacting a saturated NaCl droplet with an immiscible IL droplet. The magnitude of the generated electric current signals increases with an increase in the ionic concentration of the NaCl solution, the droplet contact area, and the liquid volume of IL. Moreover, the magnitude of the signals varies slightly when the pH value is under 12 and increases sharply in strong alkaline conditions. A maximum instantaneous power output of about 82 nW was obtained with a 100 kΩ resistor in series. The IL-based immiscible L-L interface configuration has been proven to be capable of sensing metal ions at an ultra-low concentration via the contact/separation mode.